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Journal of Southwest Petroleum University(Science & Technology Edition) 2018 Vol.40 Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Two-way Locking Mechanism Design for Telescopic Downhole Tractors LIU Qingyou, ZHENG Wei, YANG Yaqiang, ZHANG Shuyang, ZHU Haiyan 西南石油大学学报(自然科学版)    2018, 40 (1): 1-10.   DOI: 10.11885/j.issn.1674-5086.2016.12.24.01 Abstract （245）   HTML    PDF（pc） （2378KB）（639）       Knowledge map    Save Design of a two-way locking mechanism for telescopic downhole tractors, based on the principles of self-locking ramps, is reported to improve the traction capacity of telescopic downhole tractors. The proposed mechanism allows the tractor to lock itself to shaft linings in its fore and aft structure, thereby overcoming restrictions in traction force imposed by static frictional forces. This allows the tractor to be towed in both directions while also improving its traction capacity. The twoway lock comprises two locking states:the traction lock and reset lock. Through static-force analyses of both locking states, mathematical relations describing the two-way locking mechanism, when it meets the required locking conditions, were derived. Parametric design of the two-way locking mechanism was performed to ensure that the traction locking state is a self-locking state while the reset locking state is not. Subsequently, a computational model was established to simulate the dynamics of a tractor's frontal working section, thereby completing simulation of two-way locking processes. Results of these simulations have been used to validate the accuracy of the parametric design of the two-way locking mechanism, and the viability of the proposed mechanism has been proven. Reference | Related Articles | Metrics Select Paleontological Features and Sedimentary Environment of Dainan Formation in Deep Sag of Gaoyou Sag YUAN Jing, XIAO Yunfeng, DONG Daotao, XIONG Guangqin, QIU Yongfeng 西南石油大学学报(自然科学版)    2018, 40 (1): 11-21.   DOI: 10.11885/j.issn.1674-5086.2016.06.29.02 Abstract （182）   HTML    PDF（pc） （2533KB）（504）       Knowledge map    Save Based on rock core and paleontology analyses data, combined with the sedimentary facies, the relationship between fossils, such as ostracods and charophytes, and the sedimentary environment of the first and second members of the fifth sub-member of the Dainan Formation in the Deep Sag of Gaoyou Sag were systematically analyzed. Seventy species of ostracods were identified, with the Cyprididae Baird section molecules being dominant, followed by Candonidae Kaufmann, and a small number of Limnocytheridae. The vertical variation in the fossil assemblage reflects the cyclic changes in the lake water during the Dainan Period, namely, brackish water→fresh water→brackish water→brackish water→fresh water. In addition, 76 species of charophytes were identified, including Grovesichara changzhouensis, S tephanochara fortis, Obtusochara longscoluminania, and Sphaerochara parvula. The first sub-member of the first member of the Dainan Formation is most prosperous, which manifests a quiet and brackish-fresh water environment during those periods. The vertical distribution and evolution of the ostracods and charophytes fossil combination has a close relationship with the changes in and distribution of the sedimentary environment and facies. When the ostracods fossil assemblage in fresh to brackish water is in a dominant position and the chara is flourishing, it indicates that terrigenous clastic sediment is abundant. Additionally, the sedimentary facies are dominated by aggradation or a progradation delta and fan delta. When the ostracods fossil assemblage in brackish water is in a dominant position, it indicates that the terrestrial sources are short of clastic substance supply, and the retrogradation delta and fan delta are the main sedimentary facies. Reference | Related Articles | Metrics Select Analysis on the Characteristics and Variations of Member 1 of the Qingshuihe Formation in the Luxi Region WANG Jian 西南石油大学学报(自然科学版)    2018, 40 (1): 22-34.   DOI: 10.11885/j.issn.1674-5086.2016.07.12.62 Abstract （355）   HTML    PDF（pc） （3406KB）（719）       Knowledge map    Save To elucidate the reservoir characteristics and controlling factors of Member 1 of the Qingshuihe Formation (Qingshuihe Member 1), which lies to the west of the Luliang uplift, and to guide the prospecting of "sweet spots" in the reservoir, a comparative analysis between the sandstone and glutenite reservoirs of Qingshuihe Member 1 was performed through the analysis of a large numbers of rock thin-sections and casting thin-sections via scanning electron microscopy and X-ray diffraction, combined with the analysis of rock core observations, petrophysical properties, and mercury porosimetry. Significant differences were found between the microscopic and macroscopic characteristics of these reservoirs. (1) Sandstone reservoirs are mainly comprised of medium-to-fine grained feldspar lithic sandstones that are primarily distributed within the northwestern side of the research area, whereas glutenite reservoirs are mainly composed of fine conglomerate and sandy fine conglomerate that are mainly distributed in the northeastern side of the research area. (2) Reservoir spaces in sandstone are mainly comprised of primary pores, with plagioclase dissolution pores supplementing these spaces, whereas the main reservoir space in glutenite is comprised of intergranular calcite dissolution pores. (3) The average porosity of sandstone and glutenite reservoirs are 14% and 11%, respectively, indicating that sandstone reservoirs have better petrophysical properties than glutenite reservoirs. However, glutenite reservoirs have better pore-throat structures, as most of their pores are large and have coarse skewness. (4) Sandstones are strongly affected by compaction. The tectonically elevated Hedao sandstones in the north (e.g. the Xiayan-8 well) experienced weaker levels of compaction due to their shallow burial depths, and thus have better petrophysical properties. Intense carbonate cementation during the early stages of glutenite reservoir development led to the compaction of these reservoirs, and the petrophysical qualities of these reservoirs are determined by the effects of dissolution around locations where such faults developed. Reference | Related Articles | Metrics Select A Study on the Characteristics and Factors Affecting Volcanic Reservoirs in the Suhongtu Formation of the Chagan Depression YANG Yuping, ZHU Xiaomin, GUO Dianbin, LIU Xuan, GONG Zhuangzhuang 西南石油大学学报(自然科学版)    2018, 40 (1): 35-46.   DOI: 10.11885/j.issn.1674-5086.2016.07.06.04 Abstract （237）   HTML    PDF（pc） （13266KB）（424）       Knowledge map    Save The reservoir characteristics of the Suhongtu Formation in the Chagan Depression were studied using rock cores, thin sections, scanning electron microscopy, and mercury intrusion porosimetry in combination with well logging and seismic data, to identify the main factors affecting reservoir performance. Results of this study indicated that the primary reservoir spaces in volcanic rocks are gas pores, fractures, dissolution pores, dissolution fractures, and microscopic pores and fractures. Basalt gas pores, fractures and dissolution pores were broadly developed and distributed, and basalt is the main type of reservoir rock in the research area. Tuff fractures were also relatively well developed and were second only to basalt in terms of distribution, thus making tuff the second most important type of reservoir rock in the research area. The later the volcanic rocks are formed, the better is the preservation of their primary porosity and fractures. The explosive-effusive facies transition zone and parts of the upper section of the effusive facies have good petrophysical properties, and the filling of gas pores and fractures were the main cause of petrophysical degradation in volcanic rocks. Tectonic fractures and their associated weathering-induced leaching and dissolution greatly improved the reservoir performance of volcanic rocks. The clays generated during the alteration of volcanic minerals not only clog pore openings and degrade petrophysical properties, but also reduce the density of the rocks. These actions thus created the conditions for dissolution and alteration in subsequent periods. Reference | Related Articles | Metrics Select The Characteristics and Main Controlling Factors of Tight Oil Reservoir Formation in the Wolfcamp Series of the Permian Basin, USA SUN Xiangcan, TONG Xiaoguang, ZHANG Guangya, WEN Zhixin, WANG Zhaoming 西南石油大学学报(自然科学版)    2018, 40 (1): 47-58.   DOI: 10.11885/j.issn.1674-5086.2016.07.22.01 Abstract （191）   HTML    PDF（pc） （6749KB）（510）       Knowledge map    Save We conducted a deep analysis of the Wolfcamp Series tight oil reservoir formation conditions and discuss the main controlling factors of tight oil reservoir formation based on the analysis of the structural and sedimentary characteristics and systematic research on hydrocarbon source rock and reservoirs in the Wolfcamp Series of the Permian Basin. The results show that the Wolfcamp Series has good geological conditions for tight oil enrichment:excellent hydrocarbon source rocks that consist mainly of siliceous and calcareous shale and excellent " bottom-generating, top-storing" source-reservoir configuration. The main factors controlling the tight oil production and distribution are the source rock and reservoir characteristics and the source-storage configuration. The hydrocarbon source rock characteristics are the primary controlling factor because they determine the abundance of resources; the reservoir characteristics and good source-storage configuration determine the tight oil production, migration method, and hydrocarbon removal efficienc, and are crucial for the tight oil accumulation. Reference | Related Articles | Metrics Select Evolution and Quantitative Delineation of Fluvial Channel Sandbodies in Block SA of the South Turgay Basin, Kazakhstan GUO Kai, ZHAO Ruichun, FAN Leyuan, HU Shengli, LI Yang 西南石油大学学报(自然科学版)    2018, 40 (1): 59-67.   DOI: 10.11885/j.issn.1674-5086.2016.08.09.01 Abstract （184）   HTML    PDF（pc） （9591KB）（426）       Knowledge map    Save Effective delineation and evaluation of fluvial channel sandbodies are impeded by their rapid lateral variations. In this study, frequency detection, phasing, stratal slicing, geological engraving, and other techniques were comprehensively applied to study the characteristics and duration of channel development in the Upper Jurassic Akshabulak Formation, located in Block SA of the South Turgay Basin. First, the possible existence of two stages of channel sedimentary bodies with different tuning thickness was detected within the target segment using the frequency-division method. Next, wave impedance analysis and 90° phase conversion revealed relatively good agreement between the seismic negative amplitude of the target segment and channel sands. Lastly, based on a high-frequency sequence stratigraphic framework, two types of channel sands from different stages were identified and delineated using isochronous stratal slicing; single-well calibration analysis of the characteristics of channel sedimentation were combined with the amplitudes of typical stratal slices. A comprehensive analysis of various parameters, including channel sinuosity, width-thickness ratio, and reservoir volume, suggests that the early-stage channel had characteristics of a meandering river with low sinuosity. In contrast, the late-stage channel was a delta plain distributary channel, with the characteristics of a flat, straight river. In addition, the channel had a significantly higher reservoir volume in the early stage compared to the late stage. Reference | Related Articles | Metrics Select Study on the Classification and Modeling of Fracture-Vug Oil Deposits LÜ Xinrui, HAN Dong, LI Hongkai 西南石油大学学报(自然科学版)    2018, 40 (1): 68-77.   DOI: 10.11885/j.issn.1674-5086.2016.07.21.03 Abstract （329）   HTML    PDF（pc） （9926KB）（728）       Knowledge map    Save To characterize the various types, scale differences, and spatial distribution features of fracture-vug carbonate reservoir systems, we used the "classifying, categorizing, karst-facies control, multi-type integration" method and modeled the respective scales, external morphology, and internal attributes of various types of fracture-vug reservoir systems. Based on the karst origin integration principle, we integrated various types of fracture-vug reservoir systems and verified the model reliability through well drilling. The results show that this method is suitable for the geological modeling of such highly heterogenous reservoirs and can effectively characterize various reservoir systems and the spatial distribution of their parameters. Based on the model, the reserve composition of unit XX was refined; the karst cave reserves made up 63.1%, the dissolved pore reserves accounted for 34.5%, and large-scale fracture reserves accounted for 2.4% of the unit. The model simulation of oil deposit numerical values obtained better fit and simulation results. Reference | Related Articles | Metrics Select Geological Information Analysis of Horizontal Wells and 3D Modeling of Shale Gas Reservoir QIAO Hui, JIA Ailin, WEI Yunsheng 西南石油大学学报(自然科学版)    2018, 40 (1): 78-88.   DOI: 10.11885/j.issn.1674-5086.2017.05.10.04 Abstract （265）   HTML    PDF（pc） （4928KB）（562）       Knowledge map    Save Shale gas exploration is characterized by short evaluation periods and few evaluation (vertical) wells. The low density of vertical wells for evaluation aggravates technical difficulties in detailed reservoir description and geological modeling. Therefore, this study established a quantitative identification standard for the lithological, physical, and electrical properties of the study area. This standard was used to carry out fine stratigraphic division of horizontal wells and sections, as well as performing stratum thickness corrections during actual drilling, to transform horizontal wells and sections into vertical wells with multiple laterally arranged openings. On this basis, data extracted from each layer of the horizontal section were used as control points to establish a detailed structural model of the study area. In the multiple-point geological information analysis, horizontal sections were considered multiple-opening evaluation wells to obtain relevant geological parameters, effectively compensating for the lack of data in evaluation wells. Reference | Related Articles | Metrics Select A Study on Nuclear Magnetic Resonance to Reservoir Quality Evaluation ZHAO Jianbin, WAN Jinbin, LUO Anyin, CHENG Daojie, LI Huiying 西南石油大学学报(自然科学版)    2018, 40 (1): 89-96.   DOI: 10.11885/j.issn.1674-5086.2016.08.04.02 Abstract （258）   HTML    PDF（pc） （2978KB）（569）       Knowledge map    Save In view of the difficulties in evaluating the quality and assessing the productivity of low-permeability complex porestructure clastic rock reservoirs with medium to low porosity located in the middle and deep formations of the central Hebei Area, we initiated a study involving the quantitative characterization of the pore structure based on nuclear magnetic resonance spectroscopy. By combining the well testing analytical data, we determined the correlation between the lower reservoir quality limit and index and the reservoir fluid production, established an appropriate reservoir classification standard for the area, and developed a well-rounded reservoir quality and productivity evaluation technique. The application of this technique to the evaluation of reservoir effectiveness and productivity showed good results; with the high accuracy rate of 87.7%, it can provide accurate suggestions for well testing in oil field exploration and development. Reference | Related Articles | Metrics Select A New Method of Explaining the Water Saturation of Low Resistivity Reservoir with Complex Pore Structure ZHANG Hengrong, HE Shenglin, ZHENG Xiangwei, HU Xiangyang, ZENG Shaojun 西南石油大学学报(自然科学版)    2018, 40 (1): 97-103.   DOI: 10.11885/j.issn.1674-5086.2016.06.26.01 Abstract （232）   HTML    PDF（pc） （3612KB）（488）       Knowledge map    Save The gravelly sandstone reservoirs of the Liusha Formation in Wushi, Beibu Gulf are subject to complicated changes in lithology, sorting and distribution of pore throats, the resistivity of the oil layer is lower than that of the mudstone and is similar to that of the water layer, the porous tube microstructure model was used to simulate the response of pore structure and rock resistivity. It is proved that the complex pore structure of rock is an important reason for the formation of peculiar low resistivity reservoir of gravel sandstone. The Archie correction equation is proposed based on experimental "bent" rock electrical data caused by complex pore structures. The modified Archie formula is applicable to reservoirs with different pore structures. The Wushi A Oilfield gravel sandstone reservoir is evaluated by a new method, can effectively improve the oil saturation, and the results are more compatible with core capillary pressures and NMR-bound water. Reference | Related Articles | Metrics Select New Epidermal Model of Partially Perforated Deviated Well in Anisotropic Reservoir DONG Wenxiu, WANG Xiaodong, WANG Jiahang 西南石油大学学报(自然科学版)    2018, 40 (1): 104-113.   DOI: 10.11885/j.issn.1674-5086.2016.10.11.06 Abstract （161）   HTML    PDF（pc） （2897KB）（388）       Knowledge map    Save In order to study the yield-increasing effect of partially perforated deviated wells, the point sink solution in the infinite plate reservoir with closed top and bottom boundaries is obtained through mirror image inversion and then superposition of the spatial instantaneous point sink solution; then, the solution of the partially perforated deviated well is obtained by integration along the deviated well trajectory; finally, a new epidermal model of a partially perforated deviated well is acquired through the late approximation of the pressure solution. The validity of the new epidermal model is verified through comparison with previous models of deviated wells and a partially perforated well epidermis separately. The results show that the epidermal factor gradually decreases with the increase in the deviation angle and bore length of the well; the yield-increasing effect produced by the well deviation angle increase would be more obvious if the well bore length increases; the increase in the anisotropic factors of reservoir thickness and permeability would reduce the yield-increasing effect. Moreover, the well deviation angle increase would make the epidermal factor decrease significantly in the reservoir with smaller anisotropic factors of permeability, in which the partially perforated deviated well with a larger deviation angle and well bore length would have a better yield-increasing effect. Reference | Related Articles | Metrics Select Model for Capacity Forecasting of Thermal Soaking Recovery in Horizontal Wells in Heavy Oil Reservoirs MA Kuiqian, LIU Dong 西南石油大学学报(自然科学版)    2018, 40 (1): 114-121.   DOI: 10.11885/j.issn.1674-5086.2016.11.09.02 Abstract （270）   HTML    PDF（pc） （1158KB）（579）       Knowledge map    Save To address the lack of a suitable calculation model for productivity prediction of thermal soaking recovery in horizontal wells in conventional heavy oil reservoirs, by establishing composite geological model including heating zone and unheated zone and considering the difference of crude oil viscosity between the heating and unheated zones, an analytical model describing the production capacity of thermal soaking recovery in a single horizontal well was determined. Further, an equation for calculating the productivity increase of thermal soaking recovery with respect to cold recovery was proposed. The results show that the productivity multiple is mainly affected by factors such as the heating radius, oil layer thickness, and horizontal section length. Based on typical thermal recovery data in horizontal wells in the Bohai N oilfield, a mechanistic model was established. The heating radius of different soaking cycles was obtained by numerical simulation. On this basis, the increase of production capacity in different soaking cycles was calculated by the new model. It is predicted that the productivity increase of the first soaking cycle was 1.6 times, which was in good agreement with the evaluation results of the first thermal soaking cycle in the ten thermal soaking recovery horizontal wells at the Bohai N Oilfield. Reference | Related Articles | Metrics Select Novel Algorithm for Calculating Ideal Gas Phase Reactions Based on the Minimization of Free Energy ZHANG Shouxin, ZHANG Zubin 西南石油大学学报(自然科学版)    2018, 40 (1): 122-129.   DOI: 10.11885/j.issn.1674-5086.2016.10.08.01 Abstract （176）   HTML    PDF（pc） （439KB）（373）       Knowledge map    Save In this work, we propose a gradient projected Lagrangian algorithm to address the inadequacies of current free-energy minimization-based solution method for calculating the composition of the ideal gas phase equilibrium. In this algorithm, a weak convergence criterion was used as the convergence criterion of the gradient projection method. Mathematical proofs were then provided for the rationality of the weak convergence conditions used in the gradient projection method, as well as the convergence of this algorithm. On this basis, the result calculated by the gradient projection method was used as the initial value in Newton's method with Lagrange multipliers, and improvements were also made on the iteration step used in Newton's method. We have thus resolved the difficulty of selecting an initial value for Newton's method, and improved the stability and computational speed of the algorithm. The results of example calculations demonstrated that the algorithm proposed in this work converges very quickly and exhibits a high level of computational accuracy. Reference | Related Articles | Metrics Select Study on Interlayer Parameters of Bottom Water Heavy Oil Reservoir Under Single-well Condition HUANG Shijun, SONG Qianlan, CHENG Linsong, YANG Yang, ZHOU Zhonghao 西南石油大学学报(自然科学版)    2018, 40 (1): 130-140.   DOI: 10.11885/j.issn.1674-5086.2016.09.20.01 Abstract （315）   HTML    PDF（pc） （4945KB）（514）       Knowledge map    Save The main problem during the production of bottom water heavy oil reservoirs is the imbibition of the bottom water. The use of horizontal wells can effectively alleviate this production contradiction. At the same time, the existence of the interlayer can greatly reduce the rise of the bottom water, improve the recovery extent, and improve the recovery efficacy. This paper discusses the effect of the change of interlayer parameters on the production under the condition of a single well. There are many interlayer factors affecting the recovery efficacy. According to research, and considering the typicality and feasibility, three parameters, including the interlayer dimensionless area, interlayer dimensionless vertical position, and interlayer permeability, were selected for the study of the effect of interlayer parameters on production efficacy. Based on the actual parameters of the Bohai A reservoir, the numerical model of the bottom water heavy oil reservoir with interlayer was established. The production curve, water saturation rising curve, streamline field model diagram, and saturation field diagram were analyzed by the reservoir engineering method. The effect of each single factor on the production was studied:a larger interlayer corresponded to better production. The closer the interlayer is to the oil-water interface, the better the production is. The production in the case of an interlayer with low permeability is better than that in the case of a barrier. Based on the single-factor influence analysis, the orthogonal experiment was carried out, and the influence due to multiple factors was analyzed. The influence degree of the three interlayer parameters was determined. In decreasing order of influence, the parameters are:interlayer dimensionless area, interlayer dimensionless vertical position, and interlayer permeability. Reference | Related Articles | Metrics Select Study on Patterns of Change in Oil Reserve Permeability During Microfracturing of SAGD Wells CHEN Sen, LIN Botao, JIN Yan, ZHANG Lei, HUANG Yong 西南石油大学学报(自然科学版)    2018, 40 (1): 141-148.   DOI: 10.11885/j.issn.1674-5086.2016.06.21.05 Abstract （285）   HTML    PDF（pc） （2481KB）（498）       Knowledge map    Save In steam-assisted gravity drainage (SAGD) wells containing superheavy oils, reservoir microfracturing will quickly establish a connection between the upper and lower horizontal wells, thus improving initiation efficiency. To understand the changes in permeability of microfractured reservoirs and to assess the efficacy of microfracturing processes, we measured the porosity and permeability parameters of oil sand reservoirs with different physical properties from the Fengcheng oilfield in Xinjiang, and studied how the pore volume, anisotropy, and temperature of the oil sands affected their permeability. The experimental results indicated that the variations in absolute permeability and effective water permeability of these sands with their porosity or volumetric strain are consistent with the Kozeny-Carman (or Kozeny-Poiseuille) equation, regardless of whether the sands were in their in situ or shear-dilated states. The absolute permeability of the sands in the horizontal direction was found to be greater than that in the vertical direction, whereas the opposite was observed for effective water permeability. Meanwhile, the injectant temperature in microfracturing processes appears to have a negligible impact on effective water permeability. On this basis, the differences in seepage during microfracturing and cyclic steam injection were investigated from a mechanistic perspective, with the use of finite-element analysis. It was shown in case calculations that microfracturing simulations should be performed using the effective water permeability. Reference | Related Articles | Metrics Select Effects of Injection Pressure on Gas Channeling during CO 2 Flooding and a Study on Sealing of Cracks SHI Lihua, DANG Hailong, KANG Shengsong, WANG Weibo, WANG Qiang 西南石油大学学报(自然科学版)    2018, 40 (1): 149-156.   DOI: 10.11885/j.issn.1674-5086.2016.05.29.03 Abstract （217）   HTML    PDF（pc） （752KB）（358）       Knowledge map    Save To determine the impact of injection pressure on gas channeling during CO 2 flooding processes, different injection pressure schemes were set up according to actual oil recovery conditions, through which the breakthrough times with different injection pressures were measured. From this experiment, we obtained the variation of CO 2 breakthrough velocities and recovery rates with injection pressure. The results indicated that injection rate, base substrate permeability, and the size and width of cracks are the most important factors for injection pressure, and the selection of an appropriate injection rate was the key for controlling injection pressure. It was found that the injection pressure increased in proportion with the injection rate, decreased with increases in the size of the cracks, and decreased with increases in base substrate permeability. These results showed that the optimal injection rate for starch systems was 0.2 mL/min. In crack simulation experiments using rock cores, the sweep volume of a gaseous body was significantly affected by cracks in the reservoir, as the recovery rate falls below 1% for differentials larger than 1 000. The composition of the optimal high-strength gel system was:4% starch + 4% monomer + 0.05% crosslinking agent + 0.18% antigumming agent. This gel system has high strength, a gelling time between 8 and 20 h, and stable performance; hence, it is capable of sealing cracks effectively. The recovery rate reached 19% after crack sealing was performed using this gel, thus demonstrating that this gel system effectively increased the sweep volume of CO 2 flooding. Reference | Related Articles | Metrics Select Effects of Polymer Rheology on Sweep Efficiency of Heterogeneous Oil Reserves HU Ke, XUE Xinsheng, KANG Xiaodong, FENG Rusen 西南石油大学学报(自然科学版)    2018, 40 (1): 157-164.   DOI: 10.11885/j.issn.1674-5086.2016.08.29.01 Abstract （159）   HTML    PDF（pc） （1890KB）（458）       Knowledge map    Save Studies on the relationship between polymer solution rheology and the seepage characteristics in heterogeneous oil reserves provide a useful theoretical basis to improve the efficacy of polymer flooding in offshore oilfields. On the basis of the actual heterogeneity of heavy oil reservoirs in the sandstones of an offshore oilfield, we developed a two-dimensional visual sand-packed model capable of simulating reservoir heterogeneities in the seepage of oil displacement systems within the deeper parts of an oil reservoir, under high pressures. In this work, we performed a rheology experiment using injections with a fixed shear rate on three oil displacement systems. These displacement systems have significantly different rheologies, but similar shear viscosities at the same shear rate. It was shown in this experiment that oil displacement using these three oil displacement systems always resulted in wedge-shaped residual oil distributions within the similitude model. However, there were significant differences between these systems in their transparent areas and seepage patterns. It was shown that polymer solution rheology can delay the onset of ineffective cycling during fluid injections, thus improving the sweep efficiency of oil displacement in low-permeability reservoirs, resulting in increases in sweep efficiency with decreases in the power law exponent, n. Reference | Related Articles | Metrics Select Selection, Evaluation, and Formulation of Drying Agents for Tight Sand Reservoirs XIONG Yu, MO Jun, LI Peisi, ZHANG Liehui, JIANG Qian 西南石油大学学报(自然科学版)    2018, 40 (1): 165-172.   DOI: 10.11885/j.issn.1674-5086.2017.04.11.01 Abstract （166）   HTML    PDF（pc） （766KB）（453）       Knowledge map    Save Tight sand gas reservoirs generally have relatively high levels of water saturation in their original state, and tests have shown that the permeability of dry cores is more than 10 times higher than that of the original water-containing cores. In addition, various water-based working fluids will seep into a formation upon contact with the reservoir, which leads to liquid phase retention. This increases the water saturation of matrices near the well or fracture plane, thereby further decreasing the gas phase permeability of the reservoir and greatly reducing its productivity. To solve this problem, we developed a reservoir drying agent called "ACHM". We first experimentally evaluated drying agents by measuring the depletion of formation waters after injecting the drying agents. Chromatography and X-ray diffraction (XRD) methods were also used to analyze the gases produced by the reactions between the drying agent and water, and the composition of their residues. The experimental results indicate that ACHM has a delay in its reaction time that is inversely proportional to the temperature. The water consumption of the drying agent is not affected by the type and salinity of the formation waters, and the optimal molar mixing ratio of the two drying agents was 0.25. Reference | Related Articles | Metrics Select Study on the Quality Evaluation of Electric Submersible Pumps Based on Improved K-means LIU Guangfu, ZHU He, ZHOU Kaidi, JIAN Jixin, CHANG Yunfei 西南石油大学学报(自然科学版)    2018, 40 (1): 173-180.   DOI: 10.11885/j.issn.1674-5086.2016.11.25.02 Abstract （229）   HTML    PDF（pc） （607KB）（583）       Knowledge map    Save This study examines issues concerning the lifespan of electric submersible pumps and establishes assembly quality grade classifications based on underground vibration measurements. A 3D vibration model of a single electric submersible pump is established. The inflection point method is proposed to optimize the selection of the initial point for a K-means clustering algorithm. 3D synthetic method is employed to calculate the root-mean-square of the synthetic vibration acceleration in three dimensions. The improved K-means algorithm is used to perform a cluster analysis on the root-mean-square values of the synthetic vibration acceleration for 239 electric submersible pumps. Evaluation criteria for the assembly quality of electric submersible pumps are established. Quality tracking is carried out for electric pump measurements and the research results verify the rationality of the established classifications for electric pump assembly quality. According to the results, electric submersible pumps with root-mean-square synthetic vibration accelerations smaller than 1.30 m/s 2 are excellent pumps with the longest life spans. These pumps are applicable for use in high-yield wells. Pumps with values between 1.30 and 1.72 m/s 2 are considered as having good quality. Pumps with values between 1.72 and 2.35 m/s 2 have a typical lifespan and should be used carefully. Those with values higher than 2.35 m/s 2 are poor quality pumps with a short lifespan and should be repaired before use. Reference | Related Articles | Metrics Select Comparison of Dolomite Reservoir Characteristics Between the Northern Tarim Basin and Lower Qiulitage Group of Bachu PENG Jun, CAO Junjiao, LI Bin, XIA Qingsong, LIU Xinyu 西南石油大学学报(自然科学版)    2018, 40 (2): 1-14.   DOI: 10.11885/j.issn.1674-5086.2017.01.23.04 Abstract （263）   HTML    PDF（pc） （1072KB）（609）       Knowledge map    Save This study investigated differences in dolomite reservoir characteristics between the Northern Tarim Basin and the Lower Qiulitage Group of Bachu in terms of petrology, reservoir space, physical properties, porous structure, etc., through rock core description, rock thin section assessment, cathodoluminescence, scanning electron microscopy, physical property analysis, and mercury injection data. The results show that dolomite in the Northern Tarim Basin is mainly crystalline or granular. The reservoir space primarily comprises intercrystalline pores, intercrystalline dissolution pores, dissolution cavities, and fissures in various combinations. The pore throat is mainly of the coarse-fine type with good sorting and even distribution. The connectivity and physical properties are both good. Tectonic fractures and karstification also developed in this area, improving the physical properties of the reservoir. The Bachu area is dominated by crystalline dolomite and silty dolomicrite. The development and scope of dissolution cavities and fissures are much lower than in the Northern Tarim Basin, with less varied reservoir space combinations. The pore throat is mainly of the fine-micro type with poor sorting and uneven distribution. The connectivity and physical properties are also poor. The physical properties of the dolomite reservoir in Northern Tarim Basin are better than that in the Bachu area. This difference is mainly caused by the combined effects of sedimentation and diagenesis. Reference | Related Articles | Metrics Select Paleogene Source-constrained Seismic Reservoir Predictions in A Oilfield of the Southern Bohai Sea ZHANG Jianmin, QIAN Geng, ZHU Jianmin, ZHANG Lan, YUE Honglin 西南石油大学学报(自然科学版)    2018, 40 (2): 15-24.   DOI: 10.11885/j.issn.1674-5086.2016.11.18.01 Abstract （193）   HTML    PDF（pc） （4453KB）（472）       Knowledge map    Save Seismic reflections from the upper Oil Layer I (within the Middle of the Sha 3 Member in Shahejie Formation) in A Oilfield in the Southern Bohai Sea only returned a single peak, while the reservoir's thickness changed rapidly in the horizontal direction, and the accuracy of well-seismic ties were also very poor in this region. These issues posed difficulties for further improvements in the accuracy of reservoir predictions. The analysis of heavy mineral data indicated that the main source of the upper Oil Layer I in middle-western plates of the oilfield is the southwestern Kendong Uplift. The eastern plate on the other hand, is controlled by sources in the northeastern Laibei Uplift, and multi-source sedimentation is the key factor underlying the low accuracy of well-seismic ties. Based on previous well-seismic data analyses, optimal seismic amplitude attributes were selected for the analysis of amplitude attributes and sandstone content in 38 drilled wells in the upper Oil Layer I, and it was found that these quantities were linearly correlated when source-constrained. The smaller the amplitude attributes of sediments from the same source, the higher is the sandstone content, and vice versa. Source-constrained seismic reservoir predictions quantified the relationship between amplitude attributes and sandstone content, improving the accuracy of reservoir predictions in the upper Oil Layer I of the Middle of the Sha 3 Member in Shahejie Formation. Reference | Related Articles | Metrics Select Sedimentary Characteristics of Upper Paleozoic Mixed Deposits in Southeastern Ordos LIU Guizhen, ZHANG Dandan, LI Pan 西南石油大学学报(自然科学版)    2018, 40 (2): 25-34.   DOI: 10.11885/j.issn.1674-5086.2016.10.20.02 Abstract （250）   HTML    PDF（pc） （6161KB）（403）       Knowledge map    Save To identify the mixed sedimentary characteristics of the Benxi and Taiyuan formations in the southeastern part of the Ordos Basin, research was performed on mixed carbonate-clastic sedimentary layers using information derived from the region's geology, and data obtained from well logging/drilling and rock cores. Results indicate that the Benxi-Taiyuan formations are land and sea transitional facies deposits with barrier coasts, as well as mixed sediments. Lithologically, the mixed sediments in the Benxi Formation are mainly comprised of clastic rocks and limestone sandwiched between coal seams, while the Taiyuan Formation is mainly composed of argillaceous limestone and coal seams. The mixed sediment facies developed in the Benxi Formation include mixed tidal flat sediments, mixed lagoon sediments, and mixed barrier bar sediments, whereas mixed platform sediments were developed in the Taiyuan Formation. It was concluded on the basis of the region's sedimentation data that there were two modes of assemblage for the sedimentary facies:mixed barrier coast facies (developed in the Benxi Formation) and mixed continental shelf sedimentary facies (developed in the Taiyuan Formation). The main factors affecting the development of mixed sediments and their mode of assemblage were found to be tectonics, changes in sea level, and climate; in particular, mixed sedimentation was mainly caused by Multi level marine transgressions. Rich-source rocks, high-quality reservoirs, and multiple reservoir-caprock assemblages within the Benxi Formation were developed from these mixed sedimentary layers, and are highly favorable strata containing rich reserves of oil and gas. Reference | Related Articles | Metrics Select Study on Hydrocarbon Source Rock of Late Paleozoic-early Cenozoic in the Southwestern Dongpu Sag LIU Zhongliang, ZHANG Chengfu, LI Qingchen, LIU Jun, AN Hailing 西南石油大学学报(自然科学版)    2018, 40 (2): 35-45.   DOI: 10.11885/j.issn.1674-5086.2016.12.19.03 Abstract （218）   HTML    PDF（pc） （5182KB）（456）       Knowledge map    Save There are two main groups of hydrocarbon source rocks in southwest Dongpu Sag, the Carboniferous-Permian and the third member of Shahejie Formation. Their hydrocarbon generation capacity and their contribution to hydrocarbon accumulation affect the evaluation of the exploration strata and targets in this area, especially since there have been differing opinions regarding whether the third member of the Shahejie Formation can produce gas, and whether the gas reservoirs are mixed-source. By using geochemical methods, such as carbon isotopes, rare gas isotopes, natural gas compositions, and chromatography-mass spectrometry, oil and gas sources were compared and the geochemical characteristics of the source rocks were studied. The study shows that the organic matter in the source rocks of the third member of Shahejie Formation are dominated by Type Ⅱ 2 to Type Ⅲ Kerogen with high abundance and are poor-moderate grade source rocks, while the organic matter in the Carboniferous-Permian source rocks are dominated by Type Ⅲ Kerogen with high abundance and are good quality source rocks. The crude oil in the area comes from the third member of Shahejie Formation, where the source rocks are characterized by generating oil first and then entering a high-maturity stage to produce coal-type gas with heavy carbon isotopes. The Carboniferous-Permian source rocks mainly produce coal-formed gas. These two types of gas mix and become important natural gas sources in the area. The two groups of hydrocarbon source rocks are the most favorable exploration sources in this area. Reference | Related Articles | Metrics Select Fault Tectonics and Petroleum Entrapment in the Laoyemiao Region of the Nanpu Depression CHEN Weichang, YAN Jingjing, SUN Guanyu, YANG Rongchao, ZHOU Wei 西南石油大学学报(自然科学版)    2018, 40 (2): 46-56.   DOI: 10.11885/j.issn.1674-5086.2016.11.04.02 Abstract （228）   HTML    PDF（pc） （14558KB）（398）       Knowledge map    Save To elucidate the tectonic characteristics of faults in the Laoyemiao region of the Nanpu Depression and their role in the control of petroleum entrapment, the principles of tectonic analysis were used to perform an in-depth analysis of the coupling between petroleum entrapment factors and the evolution of faults. It was found in this study that fault systems in the Laoyemiao region may be broadly divided into basement and superficial faults, and the vertically developed igneous rocks constitute the ductile transfer zone of deep and shallow fault systems. The NNE and NE striking basement faults formed by forwards-extending Eocene rifts were present as multi-periodic listric fan faults, while the NEE-striking superficial fault systems formed by obliquely extended Oligocene rifts mainly occurred as horst and graben faults, and domino faults. In the Neogene layer, flower-and Y-shaped styles of deformation formed along the main fault line in the cap rocks due to the sliding deformation of deep faults, in the midst of thermal precipitation. The multi-periodic rifting of the main fault line in the Laoyemiao region was favorable for the sedimentation and maturation of source rocks, and the main fault line was also the primary channel for the vertical migration of petroleum within this region. Hence, anticlines and sloped zones are favorable areas for hydrocarbon accumulation. Reference | Related Articles | Metrics Select Evaluation of 3D Hydrocarbon Migration System in Baodao Sag in the Deep-water Area of Qiongdongnan Basin JIANG Rufeng, GUO Minggang, ZHU Jitian, ZHOU Jie, XIANG Yuangao 西南石油大学学报(自然科学版)    2018, 40 (2): 57-66.   DOI: 10.11885/j.issn.1674-5086.2016.06.26.03 Abstract （242）   HTML    PDF（pc） （15527KB）（389）       Knowledge map    Save The dominant migration path and migration direction of the Baodao Sag, were identified based on drilling and seismic data using seismic interpretation, paleostructure restoration, oil and gas migration and accumulation modeling, 3D geological modeling, and other technological approaches. Four faults with four levels, four sets of framework sand bodies, and four main structure ridges were identified in the Baodao Sag. The system of source rock-migration system-reservoir-trap in the Baodao Sag has been established, and the migration systems have been classified into three types:the T type, ladder type, and restricted meshwork-carpet type. The southern and northeastern step-fault zones are characterized by ladder type migration systems, while the Songnan low uplift and northern slope zones are characterized by restricted meshwork-carpet type systems. The migration simulation shows that the southern step-fault zone, northeastern step-fault zone, and Songnan low uplift front tectonic zone are the dominant migration directions, which are mainly characterized by vertical and lateral migration. The selection of favorable zones indicates that the southern step-fault zone is the most favorable zone, which has the configuration features of "near source, fault-sand-ridge ladder type migration, submarine fan and fan delta reservoir, and fault block-lithologic trap." Reference | Related Articles | Metrics Select Discovery and Application of the Condensed Layer in Lacustrine Facies WU Guohai 西南石油大学学报(自然科学版)    2018, 40 (2): 67-74.   DOI: 10.11885/j.issn.1674-5086.2016.11.17.02 Abstract （144）   HTML    PDF（pc） （7804KB）（418）       Knowledge map    Save The aim of this study was to determine potential reservoirs in the Jurassic Akshabulak Formation, located in Oil Field A in Kazakhstan. Logging curves for multiple wells were compared during a comprehensive reservoir study. A shale layer was discovered, which is distributed almost throughout the entire region, and has electrical characteristics of high natural gamma values and low resistivity. After comprehensive analysis of the shale layer via sequence stratigraphy, the condensed layer was confirmed to have been deposited during extensive flooding. The lateral distributional characteristics of the condensed layer were combined with geological and seismic data to establish a sedimentation model. Analysis of the sedimentation characteristics of the upper stratum of the condensed layer indicates substantial variations in sedimentation thickness at the eastern slope of the oil field. A prograding delta developed on this slope, which indicates the high-water mark period. Its leading edge was very favorable for the development of lithological and stratigraphic reservoirs. This observation was validated during the subsequent drilling and exploration process. A method for locating the condensed layer in lacustrine facies is proposed and provides new insights into the detection of lithological reservoirs. Reference | Related Articles | Metrics Select Methods for Detailed Characterization of Geothermal Fields in Complex Rift Basin LIU Jun, YANG Xipu, XU Wei, YANG Xiaoli, FANG Lei 西南石油大学学报(自然科学版)    2018, 40 (2): 75-82.   DOI: 10.11885/j.issn.1674-5086.2016.08.26.02 Abstract （238）   HTML    PDF（pc） （7817KB）（347）       Knowledge map    Save The geothermal field of rift basins in East Africa are highly complex. In particular, the geothermal gradients within Oilfield E are highly variable, which affects the characteristics of reservoir fluids and the oilfield's development strategies. A detailed analysis of the measurements taken from the oilfield revealed that the geothermal gradients displayed zoning in the horizontal plane and segmentation in the vertical axis, which is difficult to visualize using conventional research methods. Hence, we explored a method termed as zoned-segmented regression that is capable of characterizing the geothermal field variations of an oilfield in detail. This method was used to perform a detailed characterization of complex geothermals in Oilfield E. The results indicate that the average geothermal gradients in shallow ground layers is 6.10℃/(100 m), and the geothermal gradients decreases towards the northern part of the research area. The average geothermal gradients in deep-lying sections is 1.53℃/(100 m), and increases towards the north instead. Sedimentation was found to be the main factor determining the development of variations in geothermal gradients in the horizontal plane. Reference | Related Articles | Metrics Select Experimental Study on Ultrasonic Anisotropic Characteristics of Nitrogen-containing Coal Bodies ZHAO Yu, ZHANG Yugui, WANG Songling 西南石油大学学报(自然科学版)    2018, 40 (2): 83-90.   DOI: 10.11885/j.issn.1674-5086.2016.12.15.02 Abstract （167）   HTML    PDF（pc） （1407KB）（375）       Knowledge map    Save The investigation of ultrasonic response characteristics of gas-bearing coal bodies can provide the basis for application of ultrasonic technologies for testing the physical properties of coal. An independently developed coal reservoir physical property experimental system was used. Coal samples were selected from the 16-17 Coal Seam of the Pingdingshan Eighth Mine to prepare three kinds of coal samples:the parallel bedding and surface cleat ( x), parallel bedding and vertical surface cleat ( y), and vertical bedding ( z), in which the ultrasonic characteristics of nitrogen-containing coal bodies under different gas pressures and at different adsorption times were tested. The experimental results show that (1) when the axial pressure is constant, as the confining pressure increases, the elastic wave velocity of coal increases continuously, and the P-and S-wave velocity of the coal in a vacuum is slightly greater than that under normal pressure; (2) from the negative pressure state to the gas injection and adsorption state, the velocity of the coal column first decreases and then slowly increases with the extension of the gas injection duration; (3) when the axial pressure and confining pressure are constant, the P-and S-wave velocity increases with the change of gas pressure; (4) the anisotropy among the parallel bedding and surface cleat, parallel bedding and vertical surface cleat, and direction of the vertical bedding is significant, but the ultrasonic response patterns are basically the same; and (5) the relationship between the anisotropy degree of the vertical and parallel bedding and the adsorption time is significantly different between the P-and S-waves of the coal samples. The anisotropy degree of the P-wave is more sensitive to the adsorption time. Reference | Related Articles | Metrics Select Study on Influence of Permeability and Distribution of Pore Diameters in Rock Cores on Measurement of Mobile Fluid Saturation NING Ning, LI Yichao, LIU Honglin, ZHOU Shangwen 西南石油大学学报(自然科学版)    2018, 40 (2): 91-97.   DOI: 10.11885/j.issn.1674-5086.2016.04.25.01 Abstract （181）   HTML    PDF（pc） （1987KB）（433）       Knowledge map    Save To understand why the calculation of original oil saturation through mercury injection capillary pressure (MICP) curves always yields excessively large values, we measured the mobile fluid saturation of a set of selected samples using nuclear magnetic resonance (NMR), high-speed centrifugation, and conventional mercury injection experiments. Comparisons were then performed to analyze how the mobile fluid saturation in different pore diameter ranges differed from the MICP-measured value of mobile fluid saturation, to reveal the underlying causes of these differences. The experimental results indicated that, in ultralow-permeability reservoir cores (0.1 mD < K < 1.0 mD), MICP-measured saturation was significantly larger than NMRmeasured mobile fluid saturation. Our analysis revealed that this was caused by differences in the quantity of injected mercury and the volume of mobile fluids (as measured by NMR), because of the restrictions imposed by small pore throats. In lowpermeability reservoir cores (1.0 mD < K < 10.0 mD), MICP measurements of mobile fluid saturation may still result in larger values than the corresponding NMR measurements. In reservoir cores with high levels of permeability ( K > 10.0 mD), the difference between the MICP-measured saturation and the total mobile fluid saturation was relatively small. In this case, it was found that both the injected mercury and mobile fluids were mainly distributed within pore throats with radii greater than 1.00 μm. Reference | Related Articles | Metrics Select Development Program of Flooding After Huff and Puff in Offshore M Heavy Oilfield LI Yanjie, LI Na, TAN Xianhong, ZHU Guojin, ZHANG Lijun 西南石油大学学报(自然科学版)    2018, 40 (2): 98-106.   DOI: 10.11885/j.issn.1674-5086.2016.10.27.02 Abstract （218）   HTML    PDF（pc） （12800KB）（412）       Knowledge map    Save This research focused on low recovery efficiency of water flooding of unconventional underground heavy oil at Bohai, which had a crude viscosity greater than 350 mPa·s. Additionally, the research was based on the cycle of huff and puff and platform life. Offshore M heavy Oilfield was taken as an example. A numerical reservoir simulation was performed to optimize the design. This was used to compare and analyze the flooding time, as well as the injection and production parameters of four flooding patterns, namely, steam huff and puff turning into steam flooding, hot water flooding turning into multiple thermal fluid flooding, multiple thermal fluid huff and puff turning into multiple thermal fluid flooding, and hot water flooding. The results indicate that steam huff and puff turning into steam flooding has the best effect, and multiple thermal fluid huff and puff turning into multiple thermal fluid flooding has a relatively unfavorable effect. Optimal parameters of steam flooding are as follows:the flooding turning pressure is approximately 5 MPa, production-injection ratio is 1.3, steam quality at the bottom of the oil well is 0.4, injection temperature is 340℃, and steam injection speed is 240 m 3/d. Reference | Related Articles | Metrics Select Analysis of the Influence of the Development of Fracture-porosity-type Volcanic Gas Reservoir SHANG Kejian, FENG Dongmei, YE Liyou, LIU Huaxun 西南石油大学学报(自然科学版)    2018, 40 (2): 107-114.   DOI: 10.11885/j.issn.1674-5086.2017.01.08.02 Abstract （241）   HTML    PDF（pc） （1928KB）（427）       Knowledge map    Save This study involved building a seepage model of a gas reservoir under the presumption of stress sensitivity, gas slippage effect, and high-speed non-Darcy flow to study the development characteristics of the fracture-porosity-type dual media gas reservoir. The influence of different seepage effects on the gas well was analyzed through numerical simulation methods. The results indicated that the production features of the dual media gas reservoir were basically in line with those of the equivalent homogeneous gas reservoir when the interporosity flow coefficient greater than or equal to 10 -6, Consequently, the theories and methods of analyzing the equivalent homogeneous gas reservoir can be applied to study the dual media gas reservoir. At the early stage of gas well production, the stress sensitivity had little influence on the pressure drop of the pit bottom and variation in the production plateau. The effect of the stress sensitivity is enhanced at the mid-late stage. Theoretically, the influence of the stress sensitivity on the pressure drop of the pit bottom was observed earlier with the decrease in the interporosity flow coefficient, and its effect on the production plateau became greater. The high-speed non-Darcy flow had little influence on the pressure drop of the pit bottom at the early stage of the gas well production, and the influence increased at the mid-late stage. Theoretically, the influence of the high-speed non-Darcy flow on the pressure drop of the pit bottom was observed earlier with the decrease in the interporosity flow coefficient. Its effect on the production plateau also became greater. The slippage gas effect existed in the fracture-porosity-type dual media gas reservoir, but was only slight because of the reservoir and the bottom hole pressure that was comparatively higher. Reference | Related Articles | Metrics Select Optimization Study of the Horizontal Well and Injection-production Pattern in an Ultra-low-permeability Reservoir FAN Jianming, QU Xuefeng, WANG Chong, ZHANG Qingzhou, WANG Xuanru 西南石油大学学报(自然科学版)    2018, 40 (2): 115-128.   DOI: 10.11885/j.issn.1674-5086.2017.03.22.03 Abstract （178）   HTML    PDF（pc） （1891KB）（440）       Knowledge map    Save This study forms the basic principle of an injection-production well design for a horizontal well in an ultra-lowpermeable reservoir based on the understanding of the breakthrough, effect analysis, and mining rule of the horizontal well in an ultra-low-permeable reservoir to solve the problem of stable production. The following points are discussed:(1) the expanding range of the three-dimensional space of an artificial pressure crack is the foundation of the injection-production pattern design; (2) the direction of the well arrangement is perpendicular to the maximum principal stress; (3) the lateral displacement of the well network is the main supplementary energy; (4) the well spacing, distance, and horizontal section length should be optimized to improve the water flooding control area ratio; and (5) spacing must be reduced and an effective use of the gap between the reserves must be realized to improve the intensity of the single section. The technical direction and policy of further improving the development effect of horizontal wells are put forward based on the basic principles of the injection-production well pattern design along with the combination of field statistics and theoretical analysis to (1) improve the level of the single segment output; (2) improve the level of the well network pressure and optimize the well spacing for 500-600 m (the horizontal segment lengths of the reservoirs of the I, Ⅱ, and Ⅲ classes were 500-550 m, 450-500 m, and 400-450 m, respectively, and the reservoir row spacings of the I, Ⅱ, and Ⅲ classes were 150, 120~130, and 100~120 m, respectively; (3) optimize the water injection intensity of the single well using the technique of low and moderate water injection; and (4) determine the reasonable initial output of the horizontal well using the relationship between the amount of deposit, distance, and velocity of the water line. The reasonable production flow pressure injection was slightly greater than the saturation pressure before the water injection was effective, and was not less than 2/3 of the saturated pressure. Reference | Related Articles | Metrics Select Flow Field Calculation Model and Verification by Physical Model in Different Injection Production Well Pattern YE Shuangjiang, JIANG Hanqiao 西南石油大学学报(自然科学版)    2018, 40 (2): 129-134.   DOI: 10.11885/j.issn.1674-5086.2016.12.23.03 Abstract （260）   HTML    PDF（pc） （5560KB）（413）       Knowledge map    Save Regarding the problems on flow field distribution with different injection-production schemes (single injection and single production of vertical well and horizontal well, single injection and single production of horizontal well, and dual injection and single production of horizontal well), the study on mathematical calculation models of flow field and physical simulation with different injection-production schemes is carried out. Both conformal transformation and the mirror image reflection theory are applied to establish the mathematical model of the flow field for different injection-production schemes and deduce the mathematical expressions for the potential function and stream function. Thus, the inner equipotential lines and streamline distribution diagrams of different injection-production schemes are obtained. The computational results of the calculation model of the flow field for different injection-production schemes are compared and verified through a physical simulation experiment of water-oil displacement with different injection-production schemes. The results show that the calculation results of the calculation model for flow fields in different injection-production schemes are basically consistent with the physical simulation experiment results. The inner flow field for the single injection and single production of vertical and horizontal wells shows a certain linear flow, and both the water-driving wave and area are increased compared to the conventional injection-production schemes of vertical well. The inner injection-production cross-well streamline of single injection and single production in horizontal wells presents a linear flow. The area controlled by the streamline is larger; the displacement effect is better in comparison with single injection and single production of vertical and horizontal wells. The streamline near the heel end and toe end of the inner horizontal production well in dual injection and single production of a horizontal well is relatively dense; that near the mid position of the horizontal production well is relatively sparse, being easy to form a lag oil zone. Reference | Related Articles | Metrics Select Derivation and Practice of the New Gas Flooding Characteristic Curve of Reservoir with Gas Injection Flooding YUAN Zhiwang, YANG Baoquan, YANG Li, GU Wenhuan, SHANG Fanjie 西南石油大学学报(自然科学版)    2018, 40 (2): 135-141.   DOI: 10.11885/j.issn.1674-5086.2017.04.23.01 Abstract （244）   HTML    PDF（pc） （1140KB）（465）       Knowledge map    Save Because the conventional gas flooding characteristic curve fails to effectively describe actual seepage fluid (injected gas) in stratum and displaced crude oil, displacement process of gas injection development is analyzed and oil and gas seepage characteristics of miscible flooding and immiscible flooding are represented, respectively. Based on the steady seepage theory, the relational expression of the actual seepage fluid (injected gas) in stratum and displaced crude oil is derived, which is a semi-logarithmic function of cumulative gas injection volume and cumulative oil output; this is termed the new gas flooding characteristic curve, and its applicable conditions are analyzed. Relevant examples are applied to study the effect of changes to the injection production pattern and displacement mechanism on the characteristics of gas flooding curve. Under the condition of a given volume of gas injection, this curve can be used to accomplish long-term and stage-yield prediction, and can be applied at the initial stages of gas injection development. Reference | Related Articles | Metrics Select Testing and Calculation of the Pore Volume of Bottom Deposits in the Salt Rock Reservoir REN Zhongxin, YANG Haijun, LI Jianjun, LIU Jianyi, FAN Zhou 西南石油大学学报(自然科学版)    2018, 40 (2): 142-150.   DOI: 10.11885/j.issn.1674-5086.2016.12.06.02 Abstract （163）   HTML    PDF（pc） （5867KB）（407）       Knowledge map    Save Affected by the geological characteristics of the reservoir-building salt layer, generally, after cavern creation is completed, a large amount of insoluble matter will accumulate at the bottom. The existence of deposits not only reduces the effective storage volume but also results in many unfavorable factors for the overall construction of the reservoir. In order to scientifically evaluate the deposits and effectively handle them or transform them to increase the storage volume, their distribution characteristics and deposition pore volume were studied. Samples of deposited insoluble matter were obtained by indoor cavern experiments. The particle size distribution was determined by sieving. The distribution characteristics of particle size were analyzed according to the fractal distribution theory, and numerical modeling studies of the deposition pore volume were conducted based on the compressible packing model. Real cases were used in the calculations, and a comparison with field data was conducted. The results show that in the double-logarithmic coordinate system, the particle size of the bottom deposits is linearly correlated with the cumulative amount; that is, the distribution of particle size can be characterized by the fractal distribution function. The fractal dimension can be used as a distribution characteristic parameter to describe the uniformity and centrality of particles. Reference | Related Articles | Metrics Select 3D Well-path Design for Horizontal Wells in Heterogeneous Reservoirs YAN Jizeng 西南石油大学学报(自然科学版)    2018, 40 (2): 151-158.   DOI: 10.11885/j.issn.1674-5086.2017.05.28.01 Abstract （165）   HTML    PDF（pc） （1002KB）（583）       Knowledge map    Save The design and practical application of three-dimensional horizontal wells were studied to solve the problem of three-dimensional horizontal well construction using conventional directional equipment and to reduce costs. After analyzing the three-dimensional trajectory design models and comparing their advantages and disadvantages, the optimal constant tool face angle model was selected. Focusing on the six sections that make up a typical well-path (vertical, increasing, twisting, stable, increasing, and horizontal) and starting with the basic equation with the A target as the constraint, an initial azimuth model was established. After obtaining the build-up rate and the tool face angle based on the initial azimuth, the remaining trajectory parameters were calculated to complete the design of the three-dimensional horizontal well trajectory. This method was applied in the JH17P36 well using conventional equipment to obtain the following results:the vector hit the target, the coincidence rate of the actual trajectory and the design trajectory were high, and the technical indicators were excellent. The drilling example results indicated that the calculation model and the design method were accurate, reasonable, and feasible and also demonstrated the superiority of the constant tool face angle model. Reference | Related Articles | Metrics Select Assessing the Strength of Casing Pipes that Contain Corrosion Pit Defects LIAN Zhanghua, LUO Zeli, YU Hao, LIU Yang, HE Yong 西南石油大学学报(自然科学版)    2018, 40 (2): 159-168.   DOI: 10.11885/j.issn.1674-5086.2017.06.21.01 Abstract （229）   HTML    PDF（pc） （1573KB）（430）       Knowledge map    Save The corrosion of oilfield casing pipes has become increasingly severe in recent years. According to statistical data, the corrosion of the casing pipes in each block of the Dagang Oilfield has reached 34.4%, leading to problems such as severe casing damage and leakage. To address this problem, this study constructed three-dimensional finite element models for casing pipe-concrete sheath-ground strata systems with casings that contain either one or two corrosion pit defects based on elasticity theory and mechanical models of casing pipes with spherical corrosion pits. By studying the patterns of stress distribution in casing pipes using the model with two corrosion pit defects, it was found that the model with a single corrosion pit defect could be used to evaluate the casing strength if the gap between the corrosion pits exceeds 0.65 mm. The effects of the corrosion pit radius and depth on the strength of the casing pipes and the variational patterns of a casing pipe's stress concentration factors were studied herein using the single-corrosion pit defect model. The effects of steel grade on the loading of casing pipes with corrosion pitting in hydrated strata were also investigated. Consequently, the maximum stress and stress concentration factors in the casing pipes with corrosion pitting both increased with the increasing corrosion pit depth. The stress concentration factor also increased as the radius of the corrosion pit decreased. The stress concentration factor may exceed 2.0 in certain cases. Furthermore, the strata hydration accelerated the damage of casing pipes that contained corrosion pits. Reference | Related Articles | Metrics Select Working Fluid Level Extraction Technique Using Time-frequency Peak Filtering Based on Voice Activity Detection LIU Yanping, WU Jie, CHEN Yanjun, LIU Li 西南石油大学学报(自然科学版)    2018, 40 (2): 169-175.   DOI: 10.11885/j.issn.1674-5086.2017.04.04.01 Abstract （158）   HTML    PDF（pc） （658KB）（352）       Knowledge map    Save Several types of noises are generated in an oil jacket annulus, which complicates the fluid level reflection signal measurement. The real position of the fluid level reflection wave could not be accurately identified owing to interference. Thus, the time-frequency peak filtering (TFPF) method is applied, along with the voice activity detection (VAD) method in voice signal processing, to perform effective extraction of the working fluid level wave. The VAD-TFPF method first uses the short-time energy and double-threshold VAD method with a zero-crossing rate, divides the oil well signal measured using the acoustic method, and determines the effective signal data segment and data segment close to zero; then, TFPF with different window lengths is applied to perform filtering to two types of data segments. The filtering experiment and analysis are carried out to measured data under different noise intensities; the results indicate that this method has a stronger identification ability toward working fluid level waves than the wavelet threshold filtering method and is preferable for background noise suppression or for effective wave extraction. Reference | Related Articles | Metrics Select Effects of Hydrocarbon Composition on the Stability of Diesel Storage REN Lianling, XU Peng, GE Rui 西南石油大学学报(自然科学版)    2018, 40 (2): 176-182.   DOI: 10.11885/j.issn.1674-5086.2016.07.16.03 Abstract （189）   HTML    PDF（pc） （3835KB）（366）       Knowledge map    Save Diesel is known to deteriorate in quality during storage. To examine this issue, the effects of various hydrocarbon compounds on the stability of processed diesel fuels from China were investigated using typical samples of diesel. The results of the hydrocarbon composition analyses indicated that the total aromatics and paraffin contents of diesel are strongly correlated with each other (with a correlation coefficient of 0.90). Through the combined use of correlation analysis and stepwise linear regression, a correlation model was constructed for stability indicators with respect to hydrocarbon composition, and validated through fitting experiments. It was shown that this model can be used to accurately predict the stability of diesel storage. Hydrocarbon compounds with the largest impact on diesel storage stability were determined and were divided into three grades according to their influence on storage stability. It was found that acenaphthylene and tricyclic aromatic hydrocarbons have the largest influence on the deterioration of diesel quality, whereas paraffin has the greatest effect on the cetane number and calorific value of the diesel. Reference | Related Articles | Metrics Select Revisiting the Compaction Time of Chang 8 Sandstones in Southwestern Ordos Basin ZHOU Xiaofeng, LI Jing, ZHANG Jianxin, LI Shuheng, YU Junmin 西南石油大学学报(自然科学版)    2018, 40 (3): 1-10.   DOI: 10.11885/j.issn.1674-5086.2017.01.24.02 Abstract （269）   HTML    PDF（pc） （7781KB）（477）       Knowledge map    Save Owing to disagreements in the understanding of calcite cement formation, the compaction time of sandstones of the Yanchang Formation in Ordos Basin has not yet been determined. Employing scanning electron microscopy (SEM) with energy spectrometry and casted rock thin sections, the origin of calcite cement in Chang 8 sandstones in southwestern Ordos Basin was investigated. The results show that water released from mudstone compaction during phase A of the early diagenetic stage induced calcite cementation, forming type I calcite cement with evenly distributed dissemination structures or type Ⅱ 0 with patchy or scattered dissemination structures. Fluids cannot easily penetrate sandstones derived from type I calcite cementation, and thus water-rock reactions cannot take place. Type Ⅱ 0 calcite cement is transformed into type Ⅱ via dissolution-precipitation during phase A of the mid-diagenetic stage. Carbon and oxygen isotopes and fluid inclusion data cannot be used as the main reference for studying calcite cement formation because their interpretation must follow rock microstructure characteristics. In view of the above, the compaction time of Chang 8 sandstones in southwestern Ordos Basin was determined to be phase A of the early diagenetic stage, and its relationship with reservoir formation is "compaction followed by accumulation." 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