《西南石油大学学报(自然科学版)》前身为《西南石油学院学报》,创刊于1960年,是经国家教育部、科技部和新闻出版总署批准、由西南石油大学主办、国内外公开发行、以报道石油科技为主的学术性期刊。2008年11月,经国家新闻出版总署批准,《西南石油大学学报(自然科学版)》正式发行,国际标准刊号ISSN 1674-5086,国内统一刊号CN 51-1718/C。
《西南石油大学学报(自然科学版)》为中文核心期刊,2004年获教育部优秀科技期刊一等奖,2008年获“中国高校优秀期刊”称号。...More
Current Issue
10 April 2024, Volume 46 Issue 2
GEOLOGY EXPLORATION
Organic Volume Proportion in Shale: Concept, Measurement Method and Significance
YOU Lijun, FAN Daoquan, KANG Yili, ZHOU Yang, CHEN Yang
2024, 46(2):  1-14.  DOI: 10.11885/j.issn.1674-5086.2022.07.15.03
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Total Organic Content is an essential index for evaluating the oil and gas production capacity of shale, which has an impact on porosity and gas content and is also a key parameter for evaluating the ``geological sweet spot" of shale reservoir. However, TOC cannot reflect the distribution, connectivity, spatial proportion of organic matter and its influence on oil and gas flow and reservoir transformation. Through data sorting and analysis, the concept of Organic Volume Proportion was clarified and gave and analyzed the advantages and disadvantages of five calculation methods, including the formula method, scanning electron microscopy estimation method, CT scanning method, low-field NMR measurement method, and rock physics model method. The significance of organic matter volume content to developing organic-rich shale oil and gas is also discussed. The Organic Volume Proportion refers to the volume of organic matter per unit volume of shale. It is expressed as a percentage, which strengthens the importance of organic pores in shale gas reservoir evaluation and development, and enriches the evaluation parameter system of shale oil and gas reservoirs. Organic matter is the weak structural point or weak structural plane of shale, the characteristics of OVP bridge the geological sweet spot and engineering sweet spot indicators, the solubility and spatial proportion of organic matter lay the foundation for the new idea of ``removal material and increment permeability" in oil and gas reservoirs. When organic matter is taken as the object of dissolution, a small amount of organic matter dissolution will greatly increase the reservoir reconstruction volume.
Hydrocarbon Expulsion Efficiency of Shale in the Da$'$anzhai Member of Central Sichuan Basin and Its Exploration Enlightenment
ZHANG Benjian, LU Jungang, ZHANG Rui, JIANG Qijun, XIAO Zhenglu
2024, 46(2):  15-25.  DOI: 10.11885/j.issn.1674-5086.2022.06.08.03
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The hydrocarbon expulsion efficiency of source rock is an important parameter in petroleum resources assessment. The study of hydrocarbon expulsion efficiency can not only guide the resource evaluation, but also be an important scientific means to verify the reliability of the resource evaluation results. To remedy the defects of current hydrocarbon generation potential method, an improved hydrocarbon generation potential method is proposed, and the hydrocarbon expulsion efficiency of shale in the Jurassic Da$'$anzhai Member of central Sichuan Basin was obtained by using this method. The results show that under the current geological conditions, the hydrocarbon expulsion efficiency of the shale in the Da$'$anzhai Member is distributed between 0${\sim}$62.6{\percent}. With the increase of organic matter maturity, the hydrocarbon expulsion efficiency gradually increases, and the oil saturation index increases first and then decreases. When $R_{\rm o}$ is in the range of 0.95%${\sim}$1.72%, oil saturation index is greater than 100 mg/g, and the movable hydrocarbon content of shale strata is higher. The lithofacies combination has a significant effect on the hydrocarbon expulsion efficiency. In the longitudinal direction, there is a tendency for shale to expel hydrocarbon from shell limestone, the development of interlayer fractures in interbedded combinations is conducive to shale oil flow and production. It is concluded that the interbedded assemblage in the lower part of the first submember in the area with $R_{\rm o}$>1.25% is the key exploration target for shale oil in the Da$'$anzhai Member. The results can provide theoretical guidance for the exploration and development of shale oil in the Jurassic Da$'$anzhai Member of central Sichuan Basin.
Characteristics Analysis and Its Enlightenment of Shale of Low Resistivity in Wufeng Longmaxi Formation in Southern Sichuan Basin
HUANG Lisha, YAN Jianping, HU Xingzhong, ZHENG Majia, ZHONG Guanghai
2024, 46(2):  26-40.  DOI: 10.11885/j.issn.1674-5086.2022.03.07.03
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There are low resistivity anomalies of shale gas reservoirs of Wufeng–Longmaxi Formation in Changning and Luzhou areas in southern Sichuan Basin, and the gas production of low resistivity wells in different areas varies greatly. Based on the data of physical properties, geochemistry, X-ray diffraction, thin section, gas content, production test and logging curve, the characteristics, genetic factors and their effects on gas content of different types of low resistivity are studied. The results indicate that the boundary between low resistivity well and normal resistivity well in shale gas reservoir is 15 $\Omega\cdot$m, and the resistivity range of sub low resistivity well is mainly 10$\sim$100 $\Omega\cdot$m. The curve shape characteristics of low resistivity well mainly include ”`continuous decline type" ($R_{\rm t}$<5 $\Omega\cdot$m) and ``first decrease and then increase type" (5$\sim$15 $\Omega\cdot$m). The origin factors of low resistivity mainly include graphitization caused by over mature organic matter, high water saturation, high pyrite content and high clay mineral content, which play a different role in the reduction of resistivity of different types; Low resistivity wells of “continuous decline" generally have poor gas content, but the “first decrease and then return to increase" generally have good gas content. The low resistivity shale at the bottom of the syncline structural belt and at a large buried depth is usually ”continuous decline", and the gas-bearing properties and test productivity are usually very low. It is a type that needs special attention in the risk exploration and development of low resistivity shale gas.
Productivity Evaluation of Lower Karamay Formation of the Middle Triassic in Karamay Oilfield
SHI Yong, FANG Zhibin, LU Bingxiong, XU Xin, YU Jingwei
2024, 46(2):  41-52.  DOI: 10.11885/j.issn.1674-5086.2022.02.16.01
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There has a great oil and gas exploration potential in Lower Karamay Formation of 530 Well Block. However, the large differences of productivity between single wells have hindered further exploration and development work. Sedimentary and reservoir characters are searched based on combination of macro and micro data, such as observation of cores, logging, grain size, thin section, high pressure mercury injection, physical property and sentimental experiment, and make evaluation on productivity is made non-producing area with geology and engineer parameters by grey relation way. The results show that favorable reservoir micro-face is distributary channel, and development area of S2–4 and S2–5 can be enlarged by distribution trend of distributary channel. Main reservoir rock in S2 sand group is gravel, and the reserve space comprises of secondary pores and micro-faults which make pore structure complex, and the relationship between pore and permeability, grain size and oiliness is good. Engineer parameters have deeper affection on S2–4 and S2–5 reservoir productivity than geology parameters, and development potential of S2–4 and S2–5 reservoir is large.
Characteristics of Origin and Stylolites in Sandstone Reservoirs of Taiyuan Formation, Northern Ordos Basin
QI Rong, LIN Changsong, HUANG Guojia, YANG Xianghua, ZHANG Manli
2024, 46(2):  53-64.  DOI: 10.11885/j.issn.1674-5086.2022.03.23.03
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Stylolites were widely developed in Taiyuan Formation sandstones at northern Ordos Basin with complex genesis mechanisms, and have important influence on the physical properties of sandstone reservoirs. Based on comprehensive analysis of core, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and cast thin section, the geometry, mineral composition and genetic mechanism of sandstone stylolites in Taiyuan Formation are documented. The study indicates that the amplitude of sandstone stylolites in Taiyuan Formation varies obviously, and these stylolites can be classified into wave type, peak type, rectangular column type, composite type and network interweaved type. The sandstone stylolites are composed of organic carbon, quartz, illite, kaolinite, pyrite, rutile and zircon. The content of illite in the clay minerals is much higher than that in the surrounding rock, while the content of kaolinite is much lower than that in the surrounding rock. The organic matter and clay minerals of the sandstone stylolites are typical of sedimentary origin. They are catalysts for siliceous migration and precipitation, and lead to the silica precipitation and the proliferation of clastic quartz particles in the stylolites and surrounding sandstone pores. The stylolites are the products of pressure solution of sedimentary organic matter during burial, and are controlled by the diagenesis of sedimentary clay minerals and organic matters. The siliceous precipitation and quartz enlargement associated with the sandstone stylolites are the main factors for the quartz sandstone compaction in Taiyuan Formation in the study area. However, fractures which were prone to be developed along the stylolites can improve the permeability.
OIL AND GAS ENGINEERING
Effect of Supercritical CO$_2$ on Mechanical Properties of Tight Carbonate Rocks
GOU Bo, WANG Kun, LI Xiao, ZHAN Li, LIU Chao
2024, 46(2):  65-76.  DOI: 10.11885/j.issn.1674-5086.2023.09.02.01
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The supercritical CO$_2$ fracturing has the characteristics of low fracture pressure and easy formation of complex fractures in tight carbonate rock, but the mechanical mechanism of the effect of supercritical CO$_2$ on tight carbonate rocks is not clear. The physical properties, acoustic response, rock mechanical properties and fracture morphology of the tight dolomite samples from Majiagou Formation were studied by using the high temperature and high pressure supercritical CO$_2$ saturated fluid method, namely the samples were immersed in supercritical CO$_2$ + formation water for different time. The results show that with the increase of soaking time, the dissolution pore size and the porosity and permeability of the rock sample increase due to chemical corrosion, and the corresponding acoustic velocity, dynamic and static rock mechanical parameters all decrease. When the soaking time is longer than 1.0 d, the physical property parameters of the rock sample increase and the mechanical strength decreases obviously. With the increase of soaking time, the fracture morphology of rock samples develops from single low angle shear joint to high angle shear joint, conjugate joint and shear and tension composite joint. In short fracturing time($\leqslant$1.0d), the weak acid formed by supercritical CO$_2$ + formation water has limited deterioration degree to rock mechanical strength.
Interwell Geostress Field Evolution of Horizontal Well Group in Tight Oil Reservoirs
ZHANG Yupeng, Lü Zhenhu, LI Jiacheng, CHEN Xiaolu, SHENG Mao
2024, 46(2):  77-86.  DOI: 10.11885/j.issn.1674-5086.2021.11.13.01
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When horizontal well group develop tight oil reservoirs, the decrease of pore pressure will significantly change the distribution of interwell geostress. So the fractures in infill wells tend to propagate toward the depleted region, and the production of infill wells is limited. Therefore, the spatio-temporal evolution characteristics of interwell stress field in tight oil reservoirs is an important basis for well layout and fracturing optimization. Based on the porous elastic theory and the development parameters of typical tight oil reservoirs, a stress-seepage coupling model was built to find out the dynamic variation of the geostress field between horizontal wells with the decrease of pore pressure. Taking the change of pore pressure as the evaluation index when the horizontal principal stress direction inverse, carry out the effect of reservoir physical property and fracturing completion parameters on the spatial-temporal evolution of geostress. Results show that the direction of the maximum horizontal principal stress between wells changes with the decrease of pore pressure; the horizontal principal stress inversion is accelerated by the decrease of reservoir matrix permeability or well spacing or the increase of daily production per well or pressure fracture spacing. The initial pore pressure has no influence on the variation trend of horizontal principal stress, and the main factor is well spacing.
Investigation of Dominant Factors Influencing High-speed Non-Darcy Effect in Gas Wells
WANG Yang, WANG Bin, LUO Jianxin, ZHAO Chuankai, SHI Lei
2024, 46(2):  87-94.  DOI: 10.11885/j.issn.1674-5086.2022.06.10.01
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Practice in gas reservoir development has shown that the high-speed non-Darcy effect has a significant impact on gas well productivity. However, the degree to which high-speed non-Darcy effects impact different gas reservoirs varies. For gas reservoirs with lower pressures, the high-speed non-Darcy effect becomes more pronounced with increasing gas well production rate. For gas reservoirs with higher pressures, the same level of gas well production rate may not cause strong high-speed non-Darcy effects due to the strong gas compression, higher density, viscosity, and lower natural gas seepage speed under higher formation pressure. Sensitivity analysis of the primary factors influencing non-Darcy effects is conducted based on the gas well productivity equation and Reynolds number equation, including reservoir properties and gas properties. The Darcy/non-Darcy flow boundary is established based on the critical Reynolds number, and a Darcy flow chart is created for natural gas. The chart can be used to determine the strength of non-Darcy effects and provide guidance for setting production constraints for gas wells.
A Study on Stress Sensitivity and Drilling Fluid Pollution in Ultra-high Pressure Tight Gas Reservoirs in the Southern Margin
HU Yuanwei, YANG Shuokong, QIU Peng, LIU Huang, ZHAO Chuankai
2024, 46(2):  95-102.  DOI: 10.11885/j.issn.1674-5086.2022.07.04.03
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The low permeability characteristics and the contamination of drilling fluid are the main factors affecting the effective production of low permeability gas reservoirs. Based on the ultra-high temperature and high pressure resistance experimental system and CT scanning technology, the permeability stress sensitivity and drilling fluid pollution characteristics of a high temperature ultra high pressure tight gas reservoir (158.6 ℃ 146 MPa) in the southern margin of Xinjiang Oilfield were studied. The research results show that: 1) more than 90$\%$ pores in the reservoir cores are intergranular pores, and a small amount of intergranular pores are fully or half-filled by calcite cement and asphalt; 2) under the net stress of 110 MPa, the stress-sensitive permeability reduction ratio (relative to the net stress of the initial reservoir) of the two plug cores (0.001 9 mD, 0.032 5 mD) were equal to 39.28$\%$ and 16.04$\%$, respectively, which are moderately weak and weak sensitive, respectively; 3) qualitatively and quantitatively characterizing the drilling fluid invasion characteristics of the other two plunger cores (0.004 2 mD, 0.029 mD) under actual operating conditions, it was found that the drilling fluid did not break through the length of the two cores. It was tested that the drilling fluid invasion length in the 0.029 mD core was 3.86 cm, but the skin coefficient caused by it reached 6.54, which belonged to serious pollution degree. The research results provide important technical support for mastering the characteristics of high temperature and ultra-high pressure gas reservoirs, understanding of drilling fluid pollution, and for establishing subsequent reservoir protection measures.
Research on Oil-based Drilling Fluid Technology for Strong Plugging of Longmaxi Formation in West Chongqing Block
ZHONG Chengxu, LI Daoxiong, LI Zhengtao, XIE Gang, ZHANG Zhen
2024, 46(2):  103-113.  DOI: 10.11885/j.issn.1674-5086.2022.06.07.02
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In the process of drilling in the horizontal section of Longmaxi Formation in west Chongqing Block, complicated situations such as sticking, roof flooding and logging difficulties occurred frequently due to the instability of borehole wall. Through research, we found that the main reasons for this phenomenon are the development of micro-nano pores and fractures and the insufficient plugging performance of drilling fluid in the Longmaxi Formation in this block. Therefore, on the basis of strengthening the plugging performance of the field drilling fluid, the main treatment agent of drilling fluid was selected, and the strong plugging oil-based drilling fluid system suitable for the Longmaxi Formation in this block was constructed. The laboratory test results showed that no filtration occurred when the 220 nm and 450 nm microporous filtration membranes were passed, and the comprehensive performance was better than that of ordinary well pulp. After field application, no borehole instability occurred in the drilling process of the horizontal section of Longmaxi Formation. Compared with those drilled on the same platform using conventional plugging technology, the average mechanical drilling rate increased by 8.81 m/h, the gesteerable drilling period of horizontal section borehole was shortened by 2.79 d, and the platinum target drilling rate was 100$\%$, setting five drilling indexes records for deep shale gas wells in the west Chongqing Block. It shows that strong plugging oil base drilling fluid technology can meet the needs of drilling engineering in this block.
Well Spacing and Cluster Spacing Optimization for Horizontal Well Volume Stimulation
MA Zeyuan, XU Yun, WENG Dingwei, GUO Ying, YAN Xuemei
2024, 46(2):  114-124.  DOI: 10.11885/j.issn.1674-5086.2021.03.04.01
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Aiming at well spacing and cluster spacing optimization for horizontal wells, Chang 7 Formation in Ordos Basin is studied. Based on the integrated workflow through geology to engineering, 3D geological model and geomechanical model are built firstly with its geologic characteristics. Multi-stage fracturing design is simulated with various cluster spacing, and well spacing could be optimized by frequency distribution of full fracture length. Unstructured grid is used to predict the performance of a horizontal well and the best cluster spacing case is confirmed. Results from analysis of numerical simulation show that: it is recommended to optimize well spacing according to the cumulative frequency distribution of fracture length, like P90. It would be helpful to improve the controlling degree of complex fracture network on reserves. With cluster spacing ranging from 3 m to 5 m, it$'$s recommended to decrease lateral spacing to about 200 m; with tighter cluster spacing of 3 m instead of 15 m, the surface area of propped fractures could increase by 108$\%$, and volume stimulation degree increase by 142$\%$ for the target formation; with tighter cluster spacing of 3 m instead of 15 m, cumulative oil production increase by 75.91$\%$ in 3 years; rate of return on investment can$'$t be realized by cluster spacing of 3 m, and the recommended plan would be 5 m.
A Study on Comprehensive Treatment of Low Efficiency Wells in Offshore Oilfield with High Water Cut and High Recovery Stage
WANG Xinran, WANG Yanxia, WANG Xiaochao, DENG Jingfu, LI Hongying
2024, 46(2):  125-134.  DOI: 10.11885/j.issn.1674-5086.2022.06.23.02
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X Oilfield is a typical water flooding oilfield after chemical flooding in Bohai Sea, which had entered the high water cut and high recovery stage. In order to solve that gradually increasing low production and low efficiency wells and the treatment difficulty during the development and production process. By studying the factors such as sedimentary microfacies, formation physical property parameters, remaining oil tapping history, development mode change, injection-production well pattern adjustment, and stimulation measures, we conclude that the causes of low efficiency wells include abnormal water cut rise caused by reservoir conditions, energy reduction caused by imperfect well pattern, and sand production of production wells after screen fracturing. Classified treatment research has been carried out for low efficiency wells with different causes, and treatment measures such as regional flow field adjustment, layered system development, and subsidy for sand control screen have been put forward. The field practice from 2020 to 2021 shows that through the implementation of targeted treatment measures for 12 low efficiency wells in X Oilfield, the average peak daily oil increase of a single well reaches 18 m$^3$, and it is predicted that the cumulative oil increase will be achieved within the effective period of treatment by 21$\times$10$^4$ m$^3$, the low efficiency well treatment technology of the oilfield effectively releases the production capacity of the reservoir, which can provide reference for the low efficiency well treatment of similar offshore oilfields.
Study on the Probability of Human Error in Fracturing Operation Based on Combined Weighting
CHEN Bo, PANG Xiyue, FAN Chunming, DENG Li, DAI Qiping
2024, 46(2):  135-144.  DOI: 10.11885/j.issn.1674-5086.2021.11.08.05
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Fracturing operations are prone to accidents caused by human errors due to their high intensity and harsh operating environment. Analyzing the human reliability of fracturing sites is of great significance for improving the safety and efficiency of fracturing operations. Taking into consideration the influence of situational factors on the fracturing site, the combined weighting fuzzy CREAM method is proposed for human reliability analysis. The common performance conditions and CPC evaluation indicators for evaluating the human reliability of fracturing operations are established according to the environmental characteristics of fracturing operation scenarios. It contains 8 first-level common performance conditions and 36 second-level CPC evaluation indicators. Then, according to the impact of each CPC on the reliability of human performance, the variation coefficient method is used to determine the linear combination coefficient. The objective and subjective linear combination weighting of each CPC is carried out using the G1 and the entropy weight method. Finally, the method proposed in this paper is used to analyze the human reliability of a shale gas fracturing site in Sichuan. The results show that compared with the general fuzzy CREAM method, the combined weighted fuzzy CREAM method is more sensitive to the CPC evaluation data and the error probability is more accurate when at a low context level. With the reduction of the context level, the human error probability increases and the rate of change of the error probability accelerates, which is consistent with the actual working conditions on-site. The research results provide a reference for the analysis of human reliability and the quantification result optimization of human error probability at the fracturing site.
Verification Technology for Metrological Performance of Secondary Standard Devices for Natural Gas Flow
PENG Liguo, HE Jinpeng, ZHOU Gang, WAN Yuanzhou
2024, 46(2):  145-154.  DOI: 10.11885/j.issn.1674-5086.2022.01.24.08
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In response to the issue of incomplete real-time verification technology for the measurement performance of the high-precision flow standard device used for tracing the flow value of custody transfer flow meter, a study is conducted on the influencing factors of natural gas flow secondary standard device measurement, real-time verification technical indicators and methods. Large data statistical analysis technology is used in the study, and innovative real-time verification technical indicators and verification methods for the measurement performance of natural gas flow secondary standard device are proposed. We use a combined turbine working standard, and implement a combination of one-on-one verification, many-to-one verification, many-to-many verification, and total amount verification to monitor six technical indicators, including natural gas heat generation fluctuation rate, pressure and temperature weight coefficient, temperature difference between nozzles, nozzle differential pressure, and secondary standard volume flow deviation and repeatability of the turbine working standard. And we make an accurate and real-time verification of the metrological performance of the secondary standard device used for calibrating high-precision flow meters, monitor the process quality of flow meter calibration, and ensure the accuracy and reliability of each flow meter calibration result. The research results have certain guiding significance for the quality control of natural gas flow standard devices.
PETROLEUM MACHINERY AND OILFIELD CHEMISTRY
Theoretical Calculation of Tensile Limit Load of Casing Slip Effect in Ultra-deep Well
LIAN Zhanghua, WAN Zhiyong, SONG Lin, ZHAO Zhaoyang, LIN Tiejun
2024, 46(2):  155-163.  DOI: 10.11885/j.issn.1674-5086.2023.02.04.01
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In view of the excessive hanging weight of the casing at the wellhead of an ultra-deep well in an oilfield in Xinjiang, the damage of the slip tooth to the outer wall of the casing is caused, and the cumulative damage leads to the frequent occurrence of the fracture failure of the slip hanger casing. Therefore, this paper proposes the slip effect tensile limit load to evaluate the strength design of the wellhead slip hanger clamping part of the casing. Based on the third strength theory and the fourth strength theory, the calculation model of the slip effect tensile limit load of the wellhead slip hanger clamping casing is established respectively. The calculation results show that it is more reasonable to use the third strength theory to calculate the slip effect tensile limit load of the slip hanger casing from the safety point of view. However, in order to make full use of the mechanical properties of the material, the fourth strength theory should be used to evaluate the casing strength. In the limited space of the four-way, the optimal slip half cone angle is 23$°{\sim}25°$, and the optimal slip effective contact length is (135${\sim}$145) mm, which can ensure a large slip effect tensile limit load. The research methods and results of this paper will provide theoretical basis for the strength design of slip hanger wellhead casing and various safe construction operations.
Screening Mechanism of the Solid-liquid Mixture Vibration Screen
FANG Pan, LU Xiaogang, SHI Shuangquan, PENG Huan, HOU Yongjun
2024, 46(2):  164-175.  DOI: 10.11885/j.issn.1674-5086.2021.08.18.01
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Vibration screening technology is a means for the separation of solid-liquid mixture, which is widely used in solid phase control of drilling fluid, river mud treatment and dehydration of coal mine. However, the existing research lacks sufficient comprehension for the vibration screening mechanism of solid-liquid mixture, which limits the improvement of screening efficiency of vibration equipment. In order to solve this problem, the CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) coupling method is used to study the screening mechanism of solid-liquid mixture vibration screen. Firstly, Hertz-Mindlin with JKR Cohesion model is used to simulate the collision characteristics between wet particles. Secondly, porous media is used to describe the hole characteristics of screen. Then the linear vibration trajectory of the screen is simulated by using dynamic mesh. Finally, dynamic characteristics of granular materials and flow characteristics of liquid are analyzed, and the effect of vibration frequency and amplitude on the screening efficiency of solid-liquid mixture are compared. The results show that screening efficiency of solid-liquid mixture can be improved by increasing the amplitude and frequency appropriately, but when $A$>3.0 mm and $f$>22.3 Hz, the effect of vibration screen on screening efficiency of solid-liquid mixture is weakened; when $A$≤3.0 mm and $f$≤22.3 Hz, the screening efficiency of solid-liquid mixture is more sensitive to the change of amplitude, and that of the vibration frequency next to it. The passing area of solid-liquid mixture is mainly concentrated in the area where the length of the screen $L$<20$\%$.
An Analysis of the Maximum Torque Provided by Iron Roughnecks
LU Wenhong, ZHAO Guanghui, LI Tao, FENG Chuang
2024, 46(2):  176-186.  DOI: 10.11885/j.issn.1674-5086.2021.09.29.01
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Aiming at the biting and peeling phenomenon of pipe string in the process of makeup or breakout with iron roughnecks, a research method is established to describe relationships between the maximum active torque and the clamping force from aspects such as biting, cutting and friction between tong dies and pipe string. Firstly, elastoplastic calculation and damage failure analysis were carried out for the process of tong dies biting into the pipe string, and biting depths were obtained. Secondly, friction experiments between tooth-shaped friction blocks and friction rings, which was made with materials of tong dies and pipe strings respectively, were conducted to determine friction coefficients. Cutting forces were simulated by a three-dimensional finite element model of a single tooth cutting pipe steel, and maximum active torques were determined. Finally, influences of tooth shape parameters on the maximum active torque provided by the iron roughneck during makeup and breakout were analyzed. A theoretical basis is provided for optimizing both tong die structure and operating parameters and improving performances of iron roughnecks.