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    10 October 2022, Volume 44 Issue 5
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    GEOLOGY EXPLORATION
    A Study on Single Sand Body Based on Sedimentary Time Unit
    SHENG Jun, MOU Zhonghai, PU Yong, WU Tao, WANG Junlin
    2022, 44(5):  1-13.  DOI: 10.11885/j.issn.1674-5086.2020.09.17.02
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    The braided river delta front subfacies of Ⅶ sand group in the hanging wall of fault N1—N21 reservoir of Gasikule Oilfield was chosen as the object of study. The division of sedimentary time unit, the meaning and identification mark of single sand body, and configuration mode are discussed. Based on the natural gamma half amplitude point, the subzone can be divided into reservoir sedimentary time unit, interlayer sedimentary time unit, and the regional interlayer within the reservoir sedimentary time unit. The sedimentary time units of the regional interlayer and interlayer are mainly composed of mudstone, and the sedimentary time unit of the reservoir majorly consists of laterally-connected sandstone and mudstone. The complete concept of a single sand body is first proposed based on the forgoing ideas. The single sand body, which is formed under the control of sedimentation, structure, and diagenesis, is supposed to be an independent unit surrounded by an impermeable barrier layer in three-dimensional space. The identification marks of a single sand body are clarified, and the basic configuration mode of a single sand body is also summarized in this study. The author has successfully applied this method to subzone Ⅶ—5 in the Gasikule Oilfield. The two single sand bodies of the subzone level are further divided into 17 single sand bodies of sedimentary time unit level, which greatly improves the research accuracy of a single sand body.
    Characteristics of Interlayer in the B Oilfield in South China Sea and Their Effect on Remaining Oil Distribution
    XUE Cheng, XIONG Shuquan, REN Fei, HOU Kai, LI Fan
    2022, 44(5):  14-22.  DOI: 10.11885/j.issn.1674-5086.2020.06.19.02
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    In order to effectively guide tapping of the remaining oil at high water cut stage, we carry out research the origin and distribution of interlayer, and its influence on the distribution of remaining oil, using core, seismic, logging, and dynamic production data. The results show that the interlayer could be divided into three types: muddy interlayers, calcareous interlayers and physical interlayers, which is standard of logging recognition. In plane direction, interlayers could be divided into three types as well: scattered development, local continuous development, comprehensive development, which is planar classification criteria various types of interlayer. In vertical direction, single type interlayer developed in homogeneous reservoir, and composite interlayer developed in heterogeneous reservoir. We also analyze the influence of different types of interlayer on the distribution of remaining oil, and find that the remaining oil relatively enriched in the lower part of the local continuous developed and comprehensive developed interlayers, which are important direction of tapping potential in the later stage of oilfield development.
    Monitoring of Long Time Series Deformation in Karamay Oilfield Based on SBAS-DInSAR
    YU Bing, SHE Jie, ZHAO Jinzhou, ZHANG Guo, ZHOU Zhiwei
    2022, 44(5):  23-34.  DOI: 10.11885/j.issn.1674-5086.2021.01.11.02
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    The authors obtain the annual average deformation rate and long time series deformation of the Karamay Oilfield with SBAS-DInSAR and then determine the high deformation area by taking into account the mean and standard deviation. By analyzing the results of the deformation gradients from west to east and from north to south, the cumulative deformation variables of equal time interval, the proportions of high deformation areas and the deformation trend of the characteristic points, it is found that the deformation area is highly consistent with the oil exploitation areas, and the deformation is more likely to take place during oil production and water and gas injection. Besides, the deformation is inhomogeneous in space and nonlinear in time and its overall trend in the study continues to change. Finally, the diversity reflected in the cumulative deformation of feature points is closely related to the surface features. The above results show that it is of great feasibility to apply SBAS-DInSAR to monitor long term nonlinear oilfield deformation.
    Geological Structure and Exploration Potential of Tanghe Low Uplift in Nanxiang Basin
    LI Zhi, LI Teng, ZHU Yan, HE Dengfa, LI Yan
    2022, 44(5):  35-46.  DOI: 10.11885/j.issn.1674-5086.2020.05.22.01
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    Tanghe Low Uplift is a secondary positive structural unit separating Biyang Depression and Nanyang Depression in Nanxiang Basin. The study of its geological structure is of great significance to the exploration of petroleum in this area and to the analysis of the structural-sedimentary filling relationship between Biyang and Nanyang oil-rich depressions. Based on seismic, well logging and geochemical data, we analyzes the stratigraphic distribution, structural characteristics, formation and evolution, genetic mechanism of Tanghe Low Uplift, and discusses its petroleum exploration potential. The results show that the strata developed from the bottom to the top are Yuhuangding Formation, Dacangfang Formation, Hetaoyuan Formation, Fenghuangzhen Formation and Pingyuan Formation. The structure is divided into East and West blocks, which is a "Horst like" structure composed of slope zones of Nanyang and Biyang depressions separated by Tonghejie Fault; the structure is divided into North and South zones, in the form of multiple half grabens. According to the balanced geological section, the tectonic evolution of the area is divided into four stages, namely, the unified subsidence stage, the differential subsidence stage, the compression setting stage and the depression stage. The genetic mechanism of low uplift is closely related to the differential activities of boundary faults under the transformation of regional tectonic stress field. Tanghe Low Uplift has favorable conditions for hydrocarbon supply of multiple sags, effective reservoir development of multi-layer system, long-term and high-efficient transport system, vertical superposition of multiple types of traps, and has great petroleum exploration potential.
    Application of Multi-point Geostatistical Modeling in Fan Delta Sedimentary Model
    LIU Jun, YANG Xipu, Lü Wenrui, XU Wei, LIU Guangwei
    2022, 44(5):  47-60.  DOI: 10.11885/j.issn.1674-5086.2020.07.01.01
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    K Oilfield is in the stage of pre-development plan preparation. Due to inadequate drilling data and poor quality of seismic data, there are large uncertainties in the prediction of the spatial distribution of reservoirs. Through analysis of the core, logging, pressure, seismic data, we find out that the reservoir is a fan delta front sediment, with various sedimentary microfacies such as distributary channel, overbank and mouth bar. It is difficult to accurately depict the sedimentary facies model of the K Oilfield using traditional geological modeling methods. By using multi-point geostatistical modeling methods, incorporating training images reflecting geological knowledge, combined with the characteristics of the vertical microfacies combination of drilling and the distribution regularity of reservoirs, the K Oilfield face model is established with multi-dimensional constraints. The simulation results show that the K Oilfield facies model simulated by multi-point geological statistics modeling better represents the distributary channel distribution morphology and the spatial association relationship between sedimentary microfacies, and the geological uncertainty is low, which is more in line with the geological understanding. The research results have a strong guiding significance for the preparation of oilfield development plan, and also has a certain extension significance for similar sedimentary facies modeling.
    OIL AND GAS ENGINEERING
    Methods of Time Scaling-up for Spontaneous Imbibition
    WEI Bing, LI Qinzhi, LIU Chenggang
    2022, 44(5):  61-73.  DOI: 10.11885/j.issn.1674-5086.2020.05.25.01
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    In this paper, the progress of the time scaling-up methods for spontaneous imbibition (SI) processes in recent years is comprehensively reviewed. Based on the mechanism of SI, the modified and expanded models are analyzed. In addition, based on the core-scale theoretical and empirical models, the applicability and existing problems of these models in field-scale application are discussed. Representative dimensionless models and the corresponding boundary conditions are summarized. Firstly, the dominant contributing mechanisms of SI are capillary pressure and gravity, and the SI process is governed by both of these two mechanism for majority of tight reservoirs. Secondly, there exists wide gap between core-scale and field-scale studies for tight reservoirs, which thus makes the results irrelevant and mis-predicted. Therefore, to establish the time scaling-up models for SI with different media in tight reservoirs based on the modified scale analytical models with different mechanisms, are extremely important for predicting the dynamics of enhanced oil recovery in tight reservoirs.
    Dynamic Simulation Research on Circulating Temperature Change for Riserless Mud Recovery System
    ZHANG Jie, LI Xin, WANG Zhiwei, LI Cuinan, DU Xiaoxiao
    2022, 44(5):  74-84.  DOI: 10.11885/j.issn.1674-5086.2020.08.08.02
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    As the Riserless Mud Recovery (RMR) system uses the return line instead of the riser as the upward return channel of the drilling fluid, the injection and upward return path of the drilling fluid in the seawater section become two independent units, which dramatically changes the heat transfer mode of liquid. Therefore, based on the characteristics of the system, this paper builds a dynamic analysis model to simulate the circulating temperature of the different components and carries out a dynamic simulation of the circulating temperature change for the whole system. The research results show that compared with the analytical solution models built by Lima and Pereira, the model in this paper is more suitable for the actual drilling situation, and the simulation results are accurate. During the drilling operation, the operation time change causes the circulating temperature change of the whole system. The evolution of the drilling fluid density also changes the circulating temperature of the whole system. However, the variation trend is different from the operation time. The change of the operating water depth mainly affects the circulating temperature of the each component in the seawater section. The impact on the corresponding parts of the formation section is weak.
    The Theory of Pressure-difference-time of Planar Radial Fluid Flow of Oil-water Two Phase Fluid
    LIU Hailong
    2022, 44(5):  85-97.  DOI: 10.11885/j.issn.1674-5086.2020.07.09.01
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    There is a pressure difference between the bottom hole and the outer boundary of the reservoir in the process of planar radial fluid flow. In view of the problem that the oil-water two phase fluid flow under the condition of changing pressure difference, the concept of pressure-difference-time is improved and the functional relationship is studied. The research method is to use the basic fluid flow theories to derive the function relationship of pressure-difference-time. The numerical simulation method and formula calculation method are used to calculate and compare the specific examples. The results of the study are satisfactory. The improved concept of pressure-difference-time is suitable for planar radial fluid flow. The function relationship between pressure-difference-time and cumulative liquid production or cumulative water injection is obtained. The numerical simulation results of the specific example are consistent with those of the formula. The following conclusions are obtained in this paper: pressure-difference-time is a function of cumulative liquid production or cumulative water injection. The factors influencing pressure-difference-time include relative permeability curve, oil viscosity, water viscosity, permeability, cumulative liquid production or water injection per unit thickness, pore volume per unit thickness of disk-shaped reservoir in outer boundary, pore volume per unit thickness of the disk-shaped porous media in the wellbore radius.
    A Study on Liquid Extraction Method in High Water Cut Stage of Bottom Water Reservoir in Luliang Oilfield
    WU Congwen, MA Yanqing, FAN Saihua, WU Hongju, XIE Hui
    2022, 44(5):  98-104.  DOI: 10.11885/j.issn.1674-5086.2020.09.08.01
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    According to the problems in actual production of bottom water reservoir in Luliang Oilfield, the development characteristics and liquid extraction effect of typical bottom water reservoir are analyzed through comprehensive utilization of geological research, logging interpretation, production test, production test and development performance, and the key factors affecting the difference of liquid extraction are identified. The mechanism of liquid extraction and potential tapping is clarified through the classification and description of remaining oil. Combined with the actual production performance and mechanism model, the influence rules of reservoir thickness, extraction time, single well recovery degree and water avoiding thickness on liquid extraction effect are clarified. From the geological point of view, the reservoir thickness and oil thickness ratio are the objective conditions affecting the liquid extraction effect, which need to be considered in the selection of wells for liquid extraction; from the development point of view, the amplitude and timing of liquid extraction are the key factors affecting the liquid extraction effect, which need to be fully proved in the formulation of liquid extraction scheme; for bottom water reservoir, the limit of water avoiding thickness on the maximum liquid production rate is more important.
    A Study on Mechanism of EOR by Ion Matching Water Injection
    XU Shijing, WU Jiazhong, CHEN Xinglong, LIU Qingjie
    2022, 44(5):  105-112.  DOI: 10.11885/j.issn.1674-5086.2022.03.09.02
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    Water flooding is the main technology of oilfield development, with conventional mechanism of supplementing energy to the formation. However, ion matching water injection technology enhance the oil recovery through reservoir oil-water-rock interaction. Taking advantage of strong solid-liquid micro interface in the reservoir media, injection with ion matched water could improve oil displacement efficiency by matching the type and strength of ions in injected water with that in reservoir to peel off the residual oil film. Taking Xifeng Oilfield as an example, laboratory core flooding experiment, Zeta-potential measurements, Atomic force microscopy(AFM) force-distance measurement and direct numerical simulation of interfacial force are used to analyze the influencing factors of disjoining pressure as well as Zeta-potential at the oil-brine-rock interfaces, so as to explain the EOR mechanism of ions tuning water(ITW) flooding from microscale. Core flooding experiments show that both in secondary and tertiary modes, ITW can enhance oil recovery by 15.6 and 9.8 percentage point compared with coventional water flooding; Zeta-potential and AFM force-distance measurements show that Zeta-potential and disjoining pressure are influenced by the concentration and ionic type of the brine, which determine the detachment of the residual oil from rock. At the same ion concentration, the results of numerical calculation and atomic force microscopy analysis show that the disjoining pressure of Na+ is higher than that of Ca2+ and Mg2+, which shows the stronger ability to peel oil film from rock surface. Moreover, with the decrease of ion concentration of injected water, the negative value of Zeta-potential and disjoining pressure at the interface of brine-crude oil-rock are increasing, and the repulsion force between oil and rock is increasing, which makes the residual oil easier to peel off from the rock. ITW is helpful to improve the development effect of water flooding reservoir.
    The Essence and Re-recognition of Interlayer Interference
    TANG Hai, ZHANG Kaili, TANG Ruixue, Lü Dongliang, TAN Lü
    2022, 44(5):  113-124.  DOI: 10.11885/j.issn.1674-5086.2022.04.12.03
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    Due to the impact of lithology and physical properties of each layer, and the difference of formation pressure and fluid physical properties of each reservoir section in the process of production, there are always problems of mutual restriction and interference between layers in the process of commingled injection and production of multi-layer reservoir. Improper water injection development mode will lead to the difference of water absorption capacity, oil production status and water flooding degree of each layer, and show a big interlayer contradiction in production performance, thus affecting the balanced production and ultimate recovery of each layer and the whole reservoir. The interlayer interference coefficients, as defined so far, can quantitatively characterize the interlayer interference phenomena, but their physical connotation is inconsistent with the actual seepage process of water injection development. To solve the problems of early studies on interlayer interference, the research takes a typical multi-layer reservoir X of an offshore oil field as an example, using laboratory experiment method, reservoir engineering method and numerical simulation method, to analyze the root and essence of interlayer interference in early experimental testing and theoretical research of commingled production. The research results show that the interlayer interference in segmented test and overall test is caused by the disequilibrium of pressure field and seepage field of reservoir. Based on the research results, a new method of well productivity calculation, considering interlayer interference, is established. The application results show that the new methods of quantitative evaluation of interlayer contradiction and well productivity calculation, based on the essence of interlayer interference, are more consistent with the actual reservoir situation, and provide theoretical basis for predicting the productivity of commingled injection and production in multi-layer reservoirs and the formulation of strategies to reduce the impact of interlayer interference on actual production.
    A Study on the Law of Microstructure Changing and Mechanical Properties of Shale
    ZUO Luo, ZHONG Guanyu, JIANG Tingxue, WANG Haitao
    2022, 44(5):  125-134.  DOI: 10.11885/j.issn.1674-5086.2020.06.04.01
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    Currently, there is less knowledge about the effect of carbon dioxide on the microstructure and mechanical properties of shale; this study aims to obtain some parameters through designing the special experiments for researching the effect of carbon dioxide on shale. Results show that mineral composition cannot be changed after shale soaked by slick water, supercritical carbon dioxide and liquid carbon dioxide, but porosity of shale could be scaled up; as bathing time goes up, Poisson's ratio increases and elastic modulus decreases under uniaxial compression condition, which expresses plasticity characteristics of shale is more obvious; under triaxial compression test, Poisson's ratio goes down and elastic modulus is affected scarcely by those working fluid, which tells brittleness of shale is stronger than before, and carbon dioxide has best performance; tensile strength declines with soaking time goes away, and slick water performs better than carbon dioxide; compressive strength hardly weakened by three types of liquids.
    A Study on Leakage Diffusion of Gasoline Tanks by 3D Dynamics Model
    ZHANG Zhijian, WANG Xu, LIAO Kexi, ZENG Zhaoxiong, WEN Jing
    2022, 44(5):  135-150.  DOI: 10.11885/j.issn.1674-5086.2020.05.26.02
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    The largest number of vertical internal floating roof tanks in the refined oil station is 10 000 m3, In order to study the diffusion behavior of gasoline leakage and consider the influence between adjacent tanks, a 3D model of tanks is established according to the standard by FLACS software. Based on the pool model in FLACS, the diffusion behavior of pool and combustible gas cloud under the influence of different leakage rate, temperature and wind speed are discussed, respectively. The results show that the diffusion of pool and gas cloud in the double tanks is mainly restricted by the adjacent tank. Then, as in the single tank farm, it is restrained by fire dike. The severity of the disaster after gasoline leakage is evaluated according to the size of the pool and the furthest distance of combustible gas diffusion in 30 s. It is found that the greater the leakage rate, the smaller and stable the wind speed, the faster the diffusion speed of pool and combustible gas cloud, the higher the risk degree, while the temperature has little impact on the expansion of pool and gas cloud diffusion. Combined with the real-time gas concentration information of the monitoring point and the relevant provisions of GB 50493--2019, it is suggested that the combustible gas detector in the tank farm should be set near the leakage source with a height of 0.3 m.
    Simulation of Influence Range of Natural Gas Fire and Explosion Accident in Cold Vent
    JIANG Hongye, LI Wenqian, ZHANG Yongcheng, XU Taolong, GU Peng
    2022, 44(5):  151-158.  DOI: 10.11885/j.issn.1674-5086.2020.06.05.04
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    Many researches on accidental fire and explosion accidents in the cold venting operation, only consider the damage range from the shock wave overpressure, but once a fire occurs, the heat radiation intensity is also very strong, so it is necessary to study the heat radiation damage range of the fire under different influencing factors. The influence range of thermal radiation and shock wave overpressure of cold vented natural gas fire under 6 MPa and 20×104m3/h venting rate are analyzed, and then the influence range of thermal radiation and shock wave overpressure under different venting rates and different venting pressure are simulated. The results show that under the simulation condition, the vent pressure has a greater impact on the thermal radiation intensity, and the farthest distance of slight injury caused by thermal radiation is 269.72 m; under the simulated condition, the vent rate has a greater impact on the overpressure of shock wave, and the farthest distance of slight injury caused by shock wave is 198.00 m. In practical engineering, it is very important to control the venting pressure and venting rate to reduce the consequences of accidental combustion and explosion accidents.
    Uncertainty Analysis on Failure Consequence of Oil Pipeline Pool Fire
    XU Jingyuan, CHEN Jingdong, WANG Qianru, CHEN Huayan
    2022, 44(5):  159-165.  DOI: 10.11885/j.issn.1674-5086.2022.03.04.02
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    The occurrence of pool fire in oil pipeline is sudden and random. For this purpose, The uncertainty analysis model of oil pipeline pool fire accident was established by taking the three factors that have great influence on the heat radiation flux of the pool as the uncertainty parameters. The three factors were the diameter of the pool, the combustion rate and the wind speed. The value range of each uncertainty parameter was determined based on an engineering example and 30~000 random combination samples were obtained by Latin hypercube sampling method. and then, monte carlo method was used to analyze the distribution characteristics of heat radiation flux in the pool fire, and the statistical law of pool fire fatality rate at different locations away from the accident point was obtained. The results show that the mean thermal radiation flux and fatality rate decrease with the increase of distance from the accident site. The distribution of lethal areas can provide a basis for the classification of risk areas around the pipeline.
    PETROLEUM MACHINERY AND OILFIELD CHEMISTRY
    Completion Technology and Optimization Design Method of Self-adaptive Flow Control in Horizontal Well
    SONG Xianmin, LAN Shaokun, WANG Xing, TIAN Jingmeng, SONG Libin
    2022, 44(5):  166-174.  DOI: 10.11885/j.issn.1674-5086.2020.06.17.02
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    In view of the problem of high water cut in horizontal wells caused by the edge and bottom water inrush in shallow unconsolidated sandstone reservoirs, some domestic oilfields use adaptive flow regulation and water control screen pipe completion technology to control water and increase oil production, but there is less theoretical research on staged water control completion, and the experience of using conventional nozzle type water control valve in the design of related parameters cannot meet the scientific requirements of the design of self-adaptive water control screen pipe completion in horizontal wells, which affects the on-site implementation effect. This paper studies the principle of self-adaptive flow regulation and water control technology for horizontal wells and sectional technology, establishes the design method of water control valve hole size when there are differences in fluid properties and permeability in each section of horizontal wells, optimizes the precision of sand control screen pipe for shallow reservoirs in Jidong Oilfield, forms the self-adaptive flow regulation and water control completion technology and optimization design method for horizontal wells, and obtains obvious effects of precipitation and oil increase, and prolonging the production period of medium and low water cut in the application of shallow edge and bottom water reservoirs in Jidong Oilfield.
    The Study of Effect of Inhibitors on BaSO4 Crystallization Kinetic Parameters
    LI Haitao, LI Ran, LIU Tao, ZHENG Chao, LIU Wenju
    2022, 44(5):  175-184.  DOI: 10.11885/j.issn.1674-5086.2022.01.05.03
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    Taking the process of barium sulfate crystal as the research object, induction period, Gibbs free energy and activation energy of barium sulfate solution with and without odium diethylene triamine pentacetate (DTPA-5Na), ethylene diamine tetra methylene phosphonate (EDTMPS) and diethylene triamine penta (DTPMP) were analyzed based on the homogeneous theory. The impact of inhibitor on the morphology and characteristic peak also were studied by SEM and XRD respectively. It was found that the induction period and activation energy increased, Gibbs free energy of barium sulfate also increased by 10.52, 8.06, 6.18 mJ/m2 respectively at the temperature from 298 K to 318 K and concentration of Ba2+ and SO42- from 0.5～1.2 mmol/L. Meanwhile, morphology of BaSO4 crystals were changed significantly and crystalline grain was smaller and more dispersed. Characteristic peak of some surface of BaSO4 became weaker. DTPA–5Na, EDTMPS and DTPMP prevented barium sulfate from growing at different levels.