Journal of Southwest Petroleum University(Science & Technology Edition)

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Development Status of High-efficiency Rock-breaking and Speed-increasing Technologies for Deep Shale Gas Horizontal Wells

ZHU Xiaohua, LI Rui, LIU Weiji, LI Zhilin, LU Dengyun

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 1-18. DOI: 10.11885/j.issn.1674-5086.2021.04.05.01

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At present, China has basically formed the economic exploitation of shallow shale gas engineering technology system, and is moving towards deep layer (more than 3 500 m) exploitation. Deep shale gas has great development potential with rich reserve. But the problems of slow drilling speed and high cost caused by high hardness, high plasticity and high abrasiveness of deep rock are very prominent. Therefore, the efficient rock breaking methods and influencing factors in deep shale gas drilling are introduced. We analyze and summarize the efficient transmission technology of reducing friction and torsion in deep shale gas horizontal wells to improve bit breaking power; and we analyze and summarize new technologies of bit and tooth with strong attacking power and longer service, technology of rock breaking parameter enhancement by using speed-raising tool to assist bit and speed-raising tool-bit parameter matching technology that is suitable for deep shale gas, and briefly describe several new non-mechanical and efficient rock breaking methods, aiming to providing a reference for future economic and efficient exploration and development of deep shale gas.

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A Study on Evolution Law of Complex Flow Pressure in Ultra-deep Wells with High Temperature and High Pressure

DENG Hu, TANG Gui, ZHANG Lin

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 111-120. DOI: 10.11885/j.issn.1674-5086.2022.09.17.01

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Due to the high temperature, high pressure, high stress and complex formation environment during the drilling of ultra-deep wells, gas invasion is prone to occur. If not discovered in time, the bottom hole pressure will continue to decrease, and gas invasion will intensify, leading to a vicious circle that increases the risk of well control. The key technology of wellbore pressure control lies in the study of complex multiphase flow laws in ultra-deep wells, but the current research is not deep enough. This study focuses on the high-temperature and high-pressure rheological characteristics of the fluids in the ultra-deep wellbore, and establishes a complex mathematical model of the full wellbore flow based on the drift flux model. The model is solved, verified and analyzed using the example of Well ST8 for pure overflow and simultaneous overflow and leakage. Research results show that the calculated standpipe pressure and casing pressure from this model are basically consistent with the field operation data, and the calculation accuracy is high, which can be used to describe the evolution law of complex flow pressure. Under the same working conditions, the pressure drop of the coexisting overflow is higher than that of the overflow condition, and the consequences are more serious. Both density and flow rate have an effect on the bottom hole pressure, in which the density mainly affects the hydrostatic column pressure, and the displacement mainly affects the flow friction.

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Thin Reservoir Prediction and Exploration Area Selection of Qixia Formation in Longnvsi Structure, Central Sichuan Basin

LIU Hong, WANG Shuangqin, TAN Lei, TANG Song, CHEN Cong

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 19-30. DOI: 10.11885/j.issn.1674-5086.2021.09.26.01

Abstract （247）

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In recent years, a number of wells in central Sichuan have drilled high-yield industrial airflow in Qixia Formation, showing the great exploration potential of the strata. However, compared with the northwestern margin of Sichuan, the carbonate beach body of Qixia Formation in Longnvsi Area is smaller in scale and thinner in reservoir thickness, which is far lower than the seismic longitudinal resolution, and has not achieved good reservoir prediction effect, which seriously restricts the oil and gas exploration and development in the vast area of the platform. Therefore, in view of the difficulty in thin reservoir prediction in the platform, the reservoir control factors and prediction geological model of Qixia Formation in Longnvsi Area of central Sichuan are studied by comprehensively utilizing core and thin section, combined with logging and seismic data, and the idea of close combination of geology and geophysics. The results show that the reservoir of Qixia Formation in this area is mainly beach dolomite reservoir, and the reservoir rocks are mainly grain dolomite and dolomitic limestone. The main reservoir space is intergranular (dissolved) pores and caves, and a small amount of cracks are visible. The main factors controlling the formation of relatively high-quality reservoirs in Qixia Formation are the position of paleogeomorphology, sedimentary microfacies and fracture development in Qixia Period. Based on this, a thin reservoir prediction geological model of Longnvsi Qixia Formation in “Qixia Period paleogeomorphology highland+ shoal core and Shoal margin microfacies+fracture development area” is established, and on this basis, the favorable areas for reservoir development are optimized. The research results provide important support for the optimization of favorable zones for oil and gas exploration deployment in the platform of Qixia Formation.

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Prediction Method of Core Permeability and Fracture Aperture Based on Machine Learning

CHEN Lin, LI Pengwu, ZHANG Shaojun, LI Zhijie, DU Xiaoyong

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 155-163. DOI: 10.11885/j.issn.1674-5086.2021.04.30.04

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Stress sensitivity is one of the main reasons for the damage of tight sandstone gas reservoirs. The prediction of the change law of core permeability and fracture aperture under stress sensitivity damage is always the key point in the field of tight sandstone reservoir protection. Based on the stress-sensitive experiment and survey data, the core permeability prediction model and fracture opening prediction model were established by using machine learning multiple linear regression algorithm coupled with the confining pressure permeability relationship model and the K-p function parameter prediction model. The accuracy of the model was tested by correlation coefficient, root mean square error and relative error. The results show that the average correlation coefficient of the prediction results of the confining pressure permeability model in fractured and nonfractured cores is greater than 0.96. The prediction results of K-p function parameter prediction model show that the root mean square error in fractured cores is higher than that in non-fractured cores, but the relative error of fractured cores is lower than that of non-fractured cores. It shows that the permeability prediction model is more suitable for fractured cores. The coefficient of determination between the fracture opening prediction model and the measured value is 0.978, indicating a high prediction accuracy. The permeability prediction model and fracture aperture prediction model can provide guidance for the exploitation and protection of tight sandstone reservoir.

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Experimental Evaluation on the Cement Sheath Integrity of Unconventional Oil and Gas Well During Large-scale Hydraulic Fracturing

GUAN Zhigang, DENG Kuanhai, WU Yanxian, LIN Zhiwei, LIN Yuanhua

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 121-132. DOI: 10.11885/j.issn.1674-5086.2021.10.16.01

Abstract （163）

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Large-scale hydraulic fracturing of unconventional oil and gas wells will put the cement sheath in an extreme service environment, which is easily lead to the failure of the cement sheath barrier. The key to avoid the failure of the cement barrier is to investigate and understand failure mechanism of cement sheath under the alternating pressure induced by fracturing. Therefore, a self-developed experimental device is used to simulate the wellbore environment to carry out the physical test and evaluation of the sealing performance and interface mechanical performance of the full-scale“production casing- normal/high cement sheathintermediate casing” under alternating pressure. The sealing performance and interface mechanical performance of cement sheath were characterized by the number of seal failure cycles and interfacial bond strength, and the sealing performance results of ordinary cement sheath under four alternating pressures(0↗30↘0, 0↗50↘0, 0↗60↘0, 0↗70↘0 MPa) and high strength cement sheath under five alternating pressures(0↗30↘0, 0↗50↘0, 0↗60↘0, 0↗70↘0 and 0↗80↘0 MPa) are obtained. The influence of alternating pressure peak and cycles times on cement sheath integrity is analyzed, the failure mechanism and process of cement sheath integrity under alternating pressure are revealed, and the correlation between cement sheath sealing performance and interface mechanical performance is clarified. It is found that the sealing/channeling resistance and interface mechanical properties of high-strength cement sheath are obviously better than those of ordinary cement sheath. The results can provide an important basis for the optimization of cement slurry system and fracturing construction parameters in unconventional oil and gas wells.

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Engineering Geological Mechanics Issues and Research Methods in Oil and Gas Exploration and Development

LI Gao, ZHANG Yi, YANG Xu

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 72-80. DOI: 10.11885/j.issn.1674-5086.2023.02.26.01

Abstract （143）

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The role of engineering geomechanics research in complex oil and gas reservoir exploration and development, as well as in integrated geological engineering, is becoming increasingly important. However, there are still many issues that need to be explored, among which the most critical is the insufficient integration of the geological evolution and mechanics research of stratum rocks. By taking the rock mechanics properties that vary with geological evolution as the intrinsic connection, this approach integrates sedimentary facies, diagenesis, tectonic evolution, and engineering impacts to more closely combine geological and engineering factors in engineering geomechanics research. The new method formed emphasizes building regional three-dimensional geological structural models and assigning rock mechanics parameters across regional-well zone-single well scales according to the geological evolution characteristics of different rock types. After establishing regional rock mechanics phases, the parameter fields are inversely corrected by combining the interference mechanisms of well engineering, thereby optimizing and adjusting well engineering design, improving the accuracy of regional geological understanding and geological information prediction. This provides scientific research methods for stress evaluation, fracture distribution prediction, pore pressure system analysis, and productivity evaluation.

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Effect of Ion Composition on the Salt-tolerance Behavior of Medium-low Molecular Weight Polymers

WANG Lili, LIANG Yan, LI Wenhong, YUAN Guowei, CAO Miao

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 174-184. DOI: 10.11885/j.issn.1674-5086.2020.10.10.02

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In view of the practical problem of choosing the medium-low molecular weight salt-tolerance polymer for Changqing Jurassic reservoir with low permeability and high salinity, this paper systematically analyzed the influence of ion concentration and composition on the salt-tolerance behavior of three different medium-low molecular weight salt-tolerance polymers. The measurement results of viscosity, relaxation time, fluorescence and environmental scanning electron microscopy showed that, compared with the conventional salt-tolerance polymer SAV55 and the associative polymer EY-131 with lower molecular weight, the associative polymer BHXF-850 with higher molecular weight and associative monomer content had better viscosifying capacity. However, with the addition of Na ⁺, Ca ²⁺ and Mg ²⁺, the viscosity retention rate, relaxation time and solution structure number of BHXF-850 were the lowest and the structural strength was also the weakest, and the solution microstructure was significantly affected by the addition of ions. At the same time, the salt-tolerance behavior of the polymer had no obvious difference between the addition of mono-valent and divalent ions. The findings can provide reference for the optimization of medium-low molecular weight salt-resistant polymers used for chemical flooding in reservoir fields.

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Mechanical Characteristics of Natural Gas Hydrate Production Riser

HUANG Xin, KOU Jian, MAO Liangjie, LI Juan

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 143-154. DOI: 10.11885/j.issn.1674-5086.2021.03.25.02

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The riser pipe is the key channel of gas hydrate exploitation in deep water, the force and deformation of the riser are more complicated due to the formation of multiphase internal flow due to the decomposition of gas hydrate in the pipeline, and the riser of gas hydrate exploitation is prone to failure accidents under the comprehensive action of internal and external flow. In order to analyze the mechanical characteristics of hydrate production riser, the decomposition and flow of hydrate in the pipe are considered in the model and introduced into the riser vibration equation. The dynamic model of hydrate riser in marine environment coupled with internal multiphase flow is established. Finite element method is applied to discretize and solve the model. The effects of slurry density, flow rate and outlet back pressure on the mechanical response characteristics of riser in hydrate mining are analyzed by taking solid fluidization test mining technology as an example. The results show that the mass of hydrate production riser decreases and the section tension of the riser increases due to the formation of multiphase flow from hydrate decomposition. The deformation displacement, bending moment and deflection angle of hydrate production riser are all smaller than those of pure liquid riser. The maximum displacement of hydrate production riser without buoyancy block appears below the midpoint of the riser, and the bending moment and deflection angle at the bottom of the riser are the largest. The displacement, bending moment and deflection angle of hydrate production riser increase with the increase of drilling fluid density, slurry discharge and outlet return pressure of riser. Appropriate increase of the tension at the top of the riser for hydrate exploitation or configure action of the buoyancy block, reduction of the drilling fluid density and displacement, and reduction of the outlet pressure of the riser are conducive to reducing the hydrate production riser bending deformation. The research results can provide theoretical guidance for protecting the safety of hydrate production riser.

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Seismic Sedimentology Characterization of Fan-delta in Slope Belt of Eastern Liaohe Depression

HUANG Derong, ZHANG Xianguo, WANG Youjing, CAI Guogang, XIE Baoguo

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 14-28. DOI: 10.11885/j.issn.1674-5086.2021.11.21.01

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Fan delta is an important type of oil and gas reservoir in slope zone of faulted basin. Lithology and sedimentary facies vary laterally. It is difficult to characterize sedimentary facies distribution inter-wells. A typical fan-delta deposition at Tiejianglu Area in the gentle slope zone of the eastern Liaohe Sag is studied. i. Two work are carried on including isochronicity analysis of seismic reflection, and seismic characterization of sedimentary facies with multi-attributes fusion. The study reveals: 1) in fan delta deposition area, there are diachronous seismic events locally and frequency division dip difference analysis can identify significant diachronous seismic reflection; 2) the root mean square amplitude, energy half-time and skew in amplitude attributes contain the information of sandstone development degree and lithologic combination. RGB fusion of the three attributes provides a simple and effective method for seismic characterization of sedimentary facies in sparse-borehole areas; 3) in study area, there developed 3 fan deltas including 2 large fan deltas of north provenance and a small fan delta of southeast provenance. At present, the exploration and development are concentrated on the fan deltas of north provenance. This study provides an effective method for seismic characterization of fan delta sedimentary facies in gentle slope zone, and provides direction and target for further exploration in the study area.

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Evaluation Method of Water Control Effect of Conformance Flow Water Control Technology

LIU Chenglin, REN Yang, PEI Bailin, ZHAO Wei

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 94-102. DOI: 10.11885/j.issn.1674-5086.2021.05.13.02

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The evaluation of conformance flow water control technology in newly commissioned horizontal wells is usually verified by a single comparison with the offsets, but the comparison results could be greatly unreliable. Water control effect evaluation methods based on the principles of such technology can complement the existing evaluation methods. Conformance flow technology equalizes the output flow profile in each production section of horizontal well, making the axial pressure profile along the wellbore unbalanced. A short shut-in results in the redistribution of axial pressure in the wellbore, and in the process of pressure balance, the fluid in the production section with high water saturation flows out and backflows into the production section with low water saturation. Therefore, there is a correlation between the effectiveness of such techniques and the occurrence of backflow. For example, in Well LFY13-2-A7, where the conformance flow technology water control technology was applied, the water cut was stable at 85% before the well was shut in, and after the well was opened again, the water cut gradually decreased from 90.81% to 85.69% and then remained stable and slightly decreased. This phenomenon, together with referring to the data of the existing adjacent well comparison method, is fully consistent with the mechanism of the conformance flow water control technology, so it proves that this technology has played a role in water control in Well LFY13-2-A7.

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Log Interpretation and Evaluation of Hydrocarbon Source Rocks of Xujiahe Formation in the North of Central Sichuan Basin

FENG Linjie, JIANG Yuqiang, CAO Jixiang, YANG Changcheng, SONG Linke

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 31-42. DOI: 10.11885/j.issn.1674-5086.2021.09.22.01

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Based on the geochemical experiment results and logging data of source rocks, by fitting the sensitive logging values of geochemical parameters, a reliable logging interpretation model of total organic carbon content and hydrocarbon generation potential is established. At the same time, combined with the actual situation of the study area, the corresponding hydrocarbon source rock classification evaluation standards are formulated, and their plane distribution is preliminarily characterized. The results show that: 1) the source rocks of the Xujiahe Formation in the northern of central Sichuan Basin have high natural gamma, high acoustic transit time, high resistivity, and low compensation density response characteristics on logging curves; 2) the response of acoustic transit time and resistivity curves to the total organic carbon content and hydrocarbon generation potential of source rocks is relatively sensitive. Based on multiple regression between the two and measured geochemical parameters, a more reliable interpretation model for the total organic carbon content and hydrocarbon generation potential of source rocks can be obtained; 3) the total organic carbon content of the source rocks of the Xujiahe Formation in the study area is mostly 0.75% to 1.50%, and the hydrocarbon generation potential is mostly 0.60 mg/g to 1.00 mg/g, mainly composed of poor hydrocarbon source rocksl; 4) vertically, the Xu5 Member is the main source rock development zone of the Xujiahe Formation, followed by the Xu2 Member; Horizontally, the thickness of the source rock in the Xu 5 Member has a trend of thinning from west to east, while the thickness of the source rock in the Xu 2 Member has a trend of thinning from northwest to southeast.

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The Pore Structure and Controlling Factors of High-porosity and Low-permeability Carbonate

TANG Hongming, PANG Yu, WANG Xiwei, ZHAO Yuchao

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 1-13. DOI: 10.11885/j.issn.1674-5086.2021.04.09.01

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The Upper Cretaceous Khasib Formation carbonate reservoir of X Oilfield in the Middle East is a shallow-sea shelf deposit, it has the characteristics of multiple biological types and rock types, high porosity and low permeability reservoirs, and complex pore structure. Based on the Folk limestone classification scheme, this paper highlights the biological characteristics, and comprehensively compares the pore structure characteristics and control factors of different types of reservoirs on the basis of rock classification. Studies have shown that the reservoir rock types include four types of micrite bioclastic sand-clastic limestone, micrite algal clastic limestone, micrite bioclastic limestone and micritic planktonic foraminifera limestone; the type of pore structure can be divided into three types: high porosity and medium permeability medium throat type, high porosity and low permeability medium fine throat type, high porosity and low permeability fine throat type; the main factors affecting the pore structure are physical properties and structural components. Among different lithologies, the difference in biological species and content affects the development of primary pores and the strength of later diagenesis, resulting in differences in pore structure. Among the same lithology, the content of plasters controls the quality of the pore structure.

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A Study on the Threshold of Infiltration Adjustment of Tight Sandstone Gas Reservoir in the Middle and Late Stages of Development

LIU Yan, LIU Lu

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 103-110. DOI: 10.11885/j.issn.1674-5086.2021.06.15.01

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Infiltration adjustment is one of the main methods to improve recovery in the middle and late stages of gas reservoir development, but the adjustment effect is not ideal at present due to the inadequate understanding of threshold of adjustment implementation. Taking the typical tight sandstone gas reservoir of Xinchang JS ₂ as an example, we study the economic and technical threshold for infiltration adjustment of different reserve areas through economic evaluation, dynamic analysis and numerical simulation, and put forward specific technical suggestions. In type I reserve area adjustments should be made to both vertical and horizontal wells when the formation pressure is greater than 59% of the original formation pressure; when the reserve abundance is greater than 4.96×10 ⁸ m ³/km ², adjustments should be made to horizontal wells; when the formation pressure is at 47%~59%, adjustments should be made to vertical wells only. In type II reserve area, when the formation pressure is greater than 67% and reserve abundance is greater than 2.03×10 ⁸ m ³/km ², adjustments can be made to both vertical and horizontal wells; when reserve abundance is less than 2.20×10 ⁸ m ³/km ², adjustments should be made to vertical wells, and when reserve abundance is greater than 2.34×10 ⁸ m ³/km ², adjustments should be made to horizontal wells; when the formation pressure is at 51%~67%, adjustments should be made to vertical wells only. In type III reserves area, adjustments can be made only to horizontal wells when the formation pressure is greater than 88%of the original formation pressure and reserve abundance is greater than 1.30×10 ⁸ m ³/km ². Ti is estimated that recoverable reserves can increase by 4.02×10 ⁸ m ³ and recovery by 0.67% through infiltration adjustment.

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Effects of Catalyst and Environment Temperature on Heavy Oil Combustion

ZHAO Shuai, PU Wanfen, MIKHAIL A V, YUAN Chengdong

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 164-173. DOI: 10.11885/j.issn.1674-5086.2021.04.08.02

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To solve the problems of long low-temperature oxidation induction period and low combustion efficiency during insitu combustion of some heavy oil reservoirs, a set of porous medium thermo-effect cell (PMTEC) was designed and developed, and the effects catalyst type, mass percentage of catalyst, mixed catalyst, and environment temperature on heavy oil combustion were systematically evaluated using this cell. The results indicated that PMTEC could efficiently and quickly evaluate the influence of the catalyst on the combustion performance of crude oil, so as to screen out a suitable catalyst system. The mixed system [cobalt naphthenate (0.5% Co) + manganese naphthenate (0.5% Mn)] could reduce the initial temperature of combustion of heavy oil in A reservoir of Xinjiang Oilfield by 60 ℃, which meant that this catalyst system had good application prospects in catalyzing heavy oil combustion. The increase in environment temperature could significantly promote the occurrence of combustion. However, the influence of environment temperature on combustion intensity was limited.

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Characteristics of Seismic Facies of High-quality Source Rocks and Prediction of Their Distributions in the Zhu III Depression, Pearl River Mouth Basin

YOU Junjun, LEI Mingzhu, LIU Yi, ZHAI Yanan, JIANG Li

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 55-71. DOI: 10.11885/j.issn.1674-5086.2022.03.11.03

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The source rocks developed in different sedimentary environments have different geochemical characteristics and contributions to petroleum accumulation. However, the spatial distribution of the source rocks of different facies is unknow, which restricts the following petroleum exploration. Based on the comprehensive analysis of rock debris, well logging, geochemistry and seismic data, the characteristics of seismic facies of high-quality sources within the Enping Formation and Wenchang Formation as well as their distribution modes are systematically investigated. The results demonstrate that: 1) the seismic facies of the source rocks of the Wenchang Formation deposited in the semi-deep and shallow lake in the Wenchang B Sag as well as the source rocks of Enping Formation deposited in the shallow lake are featured by strong amplitude-low frequency-parallel-moderately continuous reflection, weak amplitude-low frequency-parallel-weakly continuous reflection, and moderate and weak amplitude-low frequency-parallel-moderately continuous reflection (or chaotic reflection). 2) the highquality source rocks deposited in the semi-deep lake in the Wenchang B Sag are widely distributed in the sag center and steep slope zone, whereas the source rocks deposited in shallow lake are primarily distributed in the sag center and gentle slope; however, the source rocks deposited in the semi-deep lake are only located in the sag center in the Wenchang A Sag, and the source rocks deposited in the shallow lake are well developed around the sag. Thus, source rocks deposited in the semi-deep lake and shallow lake within the Wenchang Formation in the Wenchang B Sag and that deposited in the shallow lake in the Wenchang A Sag are the primary source rocks.

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Accumulation Conditions and Main Controlling Factors of Fengcheng Formation Reservoirs in the South Slope of Mahu Sag

BIAN Baoli, LIU Hailei, JIANG Zhongfa, WANG Xueyong, DING Xiujian

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 72-84. DOI: 10.11885/j.issn.1674-5086.2021.07.08.01

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Recently, breakthroughs have been made in oil and gas exploration of Fengcheng Formation in the south slope of Mahu Sag, the conditions of hydrocarbon accumulation such as source rock and reservoir rock need to be re-recognized, and the main controlling factors of pure oil reservoir in lithologic reservoir zone need to be identified. In view of the above problems, geochemical and sedimentary reservoir testing were carried out for exploration wells in recent years, and logging, and seismic data were integrated, and the results show: 1) recently drilled wells in the study area in the outer front of fan delta facies mature and good type II hydrocarbon source rock reach of certain thickness, revealing that Fengcheng Formation source rock also exist in study area. 2) the plain facies of fan delta develops massive glutenite, and there is no mudstone cap layer inside, and the front facies of fan delta develops mudstone cap layer inside, which can be used as local cap layer; reservoir rocks are extra-low porosity and extra-low permeability reservoirs. 3) four hydrocarbon accumulation belts are identified, and massive glutenite is distributed in plain facies reservoir belt, and downdip direction water hose is formed due to the unconformity of the plain facies reservoir zone cap layer sealing; pure oil layers in fan delta front reservoirs are controlled by regional mudstone cap rock development, and outer frontal shale cap rock develops generally. We thus select a 289 km ² area favorable for exploration, guiding further exploration and deployment.

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Study on Quantitative Well Logging Interpretation of Continental Shale Oil Reservoir in Jimusar Sag

TAN Fengqi, LI Xiankun, GAO Yang, LI Yingyan, ZHANG Fang

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 29-48. DOI: 10.11885/j.issn.1674-5086.2021.04.07.01

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The continental shale oil of Permian Lucaogou Formation in Jimusar Sag is selected as the research object to establish quantitative well logging interpretation models. Core calibration logging and data mining are used to establish the quantitative well logging interpretation models of physical properties, oil-bearing properties, micro pore structure and rock mechanics respectively according to the upper and lower sweet spot. In the field application of well logging interpretation models, the accuracy of reservoir evaluation has been greatly improved, reaching more than 85%. The three well logging curves are selected by the data mining method with the multi-factor permeability calculation model, not only reflect the contribution of absolute porosity to permeability, but also consider the restriction of micro pore structure transformation on permeability, and two well logging curves of natural gamma ray and acoustic time difference are used to characterize respectively the influence of shale content and compaction-cementation effect on seepage path and seepage resistance. Compared with the single factor model, the calculation accuracy is improved by 25.6%. In addition, due to the following influences such as the borehole environment, the gravity differentiation of pore fluid and the anisotropy of formation in different directions, there is a certain deviation between horizontal and vertical well logging curves. So the quantitative well logging interpretation models based on the response characteristics of vertical well logging curves and core analysis data can not be directly applied to the reservoir evaluation of horizontal wells. In view of the above problems, the conversion chart and calculation formula of well logging curves of two measurement methods are established, and the reservoir of the horizontal section can be quantitatively interpreted.

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Study on Improvement and Effect Evaluation of Salt Resistance of “Drying Agent” in Tight Gas Reservoir

XIONG Yu, FU Xitong, ZHANG Liehui, SUN Yang

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 85-93. DOI: 10.11885/j.issn.1674-5086.2021.08.21.01

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At present, the high water saturation of the reservoir is the main reason for the low permeability of the tight gas reservoir. It has been pointed out that the desiccant which can react with the formation water to reduce the water saturation has been injected into the pores of the tight reservoir. However, the way of reducing water saturation by injecting desiccant may encounter the solid salting out produced by the reaction, resulting in pore blockage, so it is particularly important to reduce the formation of salting out on the basis of the previous study of desiccant. It is particularly important to improve the formula of desiccant. A metal carbonization complex LC containing lithium ion was used as a synergistic agent to participate in the drying reaction of the compound drying agent formula, which mainly improved the salt resistance effect of the drying agent formula, greatly reduced the formation of solid phase salting-out after the drying reaction, and analyzed the reaction heat of various chemical substances in the reaction. Combined with the experiment, the thermal effect and drying effect of the improved composite drying agent and the original drying agent were compared. Based on the results of XRD phase analysis of the salting out, EDTA and DTPA, which can complex with metal cations, were selected as salt resistance auxiliaries, and the salt resistance effects were studied under the experimental conditions of normal temperature, normal pressure and simulated formation high temperature and high pressure. the experimental results show that the desiccant system can achieve ideal salt resistance effect by adding synergist LC and salt resistance auxiliaries. That is to say, when the water consumption is the most, the solid salting out is the least, which makes the drying agent system more perfect.

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A Theoretical Study on the Corrosion and Scale Inhibition Performance of Polyepoxysuccinic Acid Derivatives

CHEN Xin, ZHANG Yizhen, CHEN Qin, LUO Liang

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 171-180. DOI: 10.11885/j.issn.1674-5086.2022.09.22.02

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In the process of oil and gas field development, tubing corrosion and scaling frequently occur, which will cause huge economic losses and serious safety problems. Adding corrosion and scale inhibitor is an effective anti-corrosion and scale prevention method, which is widely used in petroleum and petrochemical fields. In recent years, with the enhancement of public awareness of environmental protection, environmentally friendly polyepoxysuccinic acid (PESA) has been widely studied. Using quantum chemistry and molecular dynamics simulation methods to study corrosion and scale inhibition performances of PESA and polyepoxysuccinic acid derivatives (MEA-PESA). The influences of quantum chemical parameters (frontier molecular orbital energy, energy gap, bulk hardness, and Fukui index) for the corrosion inhibition efficiency are discussed. The adsorption behaviors of eight kinds of corrosion and scale inhibitors on the metal and calcium carbonate surface are investigated by molecular dynamics simulation. The results of adsorption energy show that the efficiency of corrosion and scale inhibition of PESA and MEA-PESA is enhanced with the increase of degree of polymerization.

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Vortex Induced Forced Vibration of Euler-Bernoulli Pipe-in-pipe System

ZHAO Xiang, TAN Ming, LI Yinghui, SHAO Yongbo

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 133-142. DOI: 10.11885/j.issn.1674-5086.2021.02.23.01

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In order to solve the vibration problem of a Pipe-in-pipe (PIP) system under the action of seawater, the dynamic response of the vortex induced forced vibration of the PIP system is studied. Then the numerical analysis is carried out to study influences of the outer pipe diameter, axial load, and external excitation frequency on displacement responses of the PIP system under the action of vortex. Based on Euler-Bernoulli beams theory, Lamb-Oseen vortex model is used to establish the dynamic model the PIP system, and Green function method is used to obtain the steady-state response of the forced vibration of the PIP system. Results show that as the diameter of the outer pipe increases, the vortex excitation force increases, and the position of the maximum amplitude becomes farther from the outer pipe; the axial tension has a greater impact on the outer pipe, but has a smaller effect on the inner pipe; when the dimensionless external excitation frequency sets to 0.4, the displacement of the outer pipe exceeds the limit of allowable deformation, and periodic collisions between the inner and outer pipe can easily happen, which cause damage to the PIP system.

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Characteristics and Sedimentary Facies Model of Wandering Braided Rivers

WANG Haikao, WANG Miao, YU Zhongliang, YU Chenglin, YIN Yanshu

Journal of Southwest Petroleum University(Science & Technology Edition) 2024, 46 (1): 35-52. DOI: 10.11885/j.issn.1674-5086.2022.01.13.04

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Aiming at the problem of unclear knowledge and unclear patterns of sandy braided river in Guantao Formation of Block Gao 104-5 in Jidong Oilfield, a classification study of sandy braided rivers was carried out, using criteria including regional geological background, paleoclimate, rock grain size, bedding structure and facies sequence, levee and mud drapes, and sand body morphology. The study area is determined to be a wandering braided river. Then, the architectural element analysis method from Miall is adopted to anatomize the wandering braided river. The two types of identification marks of braided belt boundary and 3 types of identification marks of river channel and mid channel bar are constructed to anatomize the wandering braided channel. The result shows that the scale of the channel belts are about 1 400.00 m wide, the width and length of mid channel bar are about 158.86 m and 414.47 m, respectively; the width of channel is 53.18 m. and the length/width of mid channel is about 2~4; the average width of mid channel bar and channel is 2.2. So the study area is categorized as the wide bar and narrow channel pattern. Finally, using depositional simulation methods, a wandering braided river sedimentary facies model in the study area was established to guide oilfield development.

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Leakage and Explosion Simulation Analysis of Injection Production Pipeline of Gas Storage Based on PHAST

CHEN Lei, ZHANG Zhe, ZHANG Xinpeng, LIU Qian, CHEN Guifang

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 131-142. DOI: 10.11885/j.issn.1674-5086.2021.08.13.03

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In order to improve the safety in operation of injection, production and gathering pipeline in underground gas storage, aiming at the problem of casualties caused by pipeline leakage explosion, based on the field production characteristics of the gas storage operation area, the main influencing factors of pipeline leakage and explosion accident were analyzed using Fault Tree Method. In addition, simulated by PHAST software, the effect of injection production pipeline operating pressure and pipeline transmission medium on the consequences of leakage and explosion accident was quantitatively analyzed, and risk assessment of the accident was carried out. It showed that under the selected simulation parameters, the hazard range of pipeline accidents increases with the increase of pipeline operating pressure, and the high-risk areas formed by gas cloud diffusion and explosion shock waves are both small. The leakage of gas flow pipeline with wet gas transmission mode will cause various fire accidents such as jet fire and pool fire. The risk assessment curve intuitively showed the harm caused by the injection, production and gathering pipeline of the gas storage to the enterprise personnel around the well station, buildings and ground operators of the gas storage. The research conclusions of this paper can provide a reference basis for the construction of emergency plan system and the improvement of disposal capacity in the operation area of gas storage.

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Oil & Gas Potential Characterization and Evaluation of Typical Continental Shale-sandstone in Northern Sichuan Basin

OU Chenghua, LI Hang, SHI Baiqiang, ZHANG Zhiyue, HE Jian

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 61-71. DOI: 10.11885/j.issn.1674-5086.2021.08.08.01

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The Qianfoya Formation in northern Sichuan Basin is rich in oil & gas resources and it is expecting to exploration and development. On basis of core analysis, logging interpretation and sedimentary microfacies analysis, we analyze the vertical, horizontal and plane distribution characteristics of reservoir, find five types of the continental shale-sandstone oil & gas reservoirs, such as multi-layer tight sandstone oil & gas reservoir, upper shale-lower sand oil & gas reservoir, sand-shale interbedded oil & gas reservoir, shale-clad sand oil & gas reservoir and isolated oil & gas reservoir, evaluate total 44 oil & gas reservoirs in each layer, and select the three favorable oil & gas reservoir A, B, and C in the Qianfoya Formation in the study area. The above results are conducive to the further development of the continental shale oil & gas reservoir geology in China.

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Numerical Simulation of CO ₂ Associated Gas Mixing Process

ZHANG Tao, YANG Ruofan, CHANG Wenjie, CHEN Bin

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 143-153. DOI: 10.11885/j.issn.1674-5086.2021.11.10.01

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In the late stage of CO ₂ flooding production in low permeability oil and gas fields, the produced product is associated gas containing a large amount of CO ₂. In the further production process, the associated gas from different sources needs to be measured and treated. In order to solve this problem, the geometric model and numerical model of CO ₂ gas diffusion flow are established by Fluent software, and then we study the mixing distance of gas diffusion under field conditions, which provides a basis for the installation position of on-line Chromatograph. The results show that CO ₂ associated gas from different gas sources is not fully mixed immediately after entering the mixing pipe; obvious mixing occurs after diffusion for a certain distance along the length direction of the pipe with the velocity on both sides gradually decreasing, and the concentration difference decreasing. With the increase of gas flow velocity and pressure, the homogeneous mixing distance of gas diffusion increases with the increase of component B. When the component content is A, B and C, the mass fraction of CO ₂ and CH ₄ reaches a stable value at about 40, 45 and 30 m. It is recommended to install a gas chromatograph at this position and select a sampling point for measurement.

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Mesozoic Faults and Their Control on Oil Reservoirs in Ordos Basin

LUO Anxiang, LIU Guanglin, LIU Zhengpeng, SHEN Tiandan, MA Shuang

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (4): 43-54. DOI: 10.11885/j.issn.1674-5086.2021.10.25.05

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Aiming at the problems of complex fault system and unclear reservoir distribution in Gufengzhuang Area, Yanchi County, northwest of Ordos Basin, using three-dimensional seismic and balanced profile restoration technology, we identify the fault distribution, delineate the morphology of the fault plane and restore the opening and closing state of the fault, and clarify the formation stage of the faults and favorable reservoir forming conditions. Three fault systems are developed in Gufengzhuang Area. Indosinian faults are mostly normal faults, distributed in en echelon arrangement in NWW direction, opened in the early Cretaceous, and played a role in connecting oil sources and efficiently transporting oil and gas. Yanshanian faults are developed in the west of the area, showing a nearly NS direction, mostly thrust faults, with strong structural deformation, which is not conducive to reservoir preservation. Himalayan faults are in NEE direction, distributed in parallel in the work area, mostly normal faults, formed after reservoir formation, adjusted or destroyed the primary reservoir. The reservoir forming conditions in the fault development area are as follows: the faults communicating with oil source opened in the reservoir forming period; the traps had good conditions and located near the convex ridge of the fault plane (reservoir forming above the source) or near the concave ridge (reservoir forming below the source). The research results have certain guiding significance for oil and gas exploration in fault system development areas.

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Design and Optimization Analysis of Downhole Linear Generator Based on Orthogonal Test

ZHONG Gongxiang, SHEN Wei, LEI Pengyan, SONG Hua, ZHONG Shengji

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 154-162. DOI: 10.11885/j.issn.1674-5086.2020.11.06.01

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Aiming at the disadvantage of low power generation in the existing downhole power supply mode and combining the advantages of linear power generation, a new cylindrical downhole linear induction power generation scheme is proposed, which generates induced current by the relative motion between the sucker rod and the oil pipe. According to the principle of existing electrical machinery, we complete the structural design of the cylinder type permanent magnet linear generator; then we use Ansoft Maxwell to analyze the no-load flux density, no-load induced electromotive force, resistive load and the power generation performance of the cylindrical permanent magnet generator under the condition of actual sealing, and verify the validity of the generator design. Finally, the key structural parameters are optimized by using the orthogonal experimental optimization method, taking distortion rate and power generation as the optimization objectives. The results show that the generator has low harmonic distortion rate, high power and good stability no matter under load or no load. It can effectively solve the problems of low efficiency and unstable performance of existing downhole generators.

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Apparent Permeability Model Considering Different Pore Characteristics of Shale Matrix

LI Heting, ZENG Jie, LI Zhenxiang, LU Qianli

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 109-118. DOI: 10.11885/j.issn.1674-5086.2022.10.08.02

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Shale matrix stores a larger amount of gas and provides a long-term gas supply for shale gas production. Therefore, matrix permeability variation with the change of pore pressure directly affects long-term productivity. Micro- and nano-pores are well developed in shale matrix. These organic and inorganic pores involve different mechanical properties and gas transport mechanisms, the variation of effective stress and flow regimes all affects their apparent permeability. Moreover, gas-adsorptioninduced organic matter swelling also influences the apparent permeability to varying degrees. Based on the poroelasticity theory, this paper establishes an apparent permeability model suitable for shale matrix with consideration of different mechanical properties and fluid flow mechanisms in organic and inorganic pores and gas-adsorption-induced deformation. The impacts of different pore properties are analyzed, and the controlling factors for apparent permeability evolution are figured out. Results indicate that shale matrix apparent permeability evolution is time-dependent during constant-pressure gas injection and depletion. The evolution process is mainly dominated by gas rarefaction effects, effective stress variation, and localized sorption-induced swelling or desorption-induced shrinkage near organic pores. These factors control apparent permeability at different times. The evolution process is also related to the ratios of the volume of organic and inorganic pores to the total pore volume.

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Characterization and Effectiveness Evaluation of Deep Reservoir Fractures Under Oil-based Mud

YANG Fenglai, CHEN Rong, ZHOU Qing, WANG Jun, DAI Li

Journal of Southwest Petroleum University(Science & Technology Edition) 2024, 46 (4): 51-64. DOI: 10.11885/j.issn.1674-5086.2024.04.30.01

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The Kuqa Area is a typical fractured tight sandstone reservoir with dense lithology and low porosity. Validity of fractures is a key factor in the formation of a good reservoir. Therefore, how to accurately identify fractures and evaluate their effectiveness is the primary problem in oilfield exploration and development. Due to the needs of drilling engineering, most wells in the Kuqa Area are drilled with oil-based mud. The electrical conductivity of oil-based mud is poor, and it is difficult to effectively identify fractures with early oil-based mud electrical imaging logging tools due their low resolution. Therefore, the combination of oil-based mud electrical imaging logging tools (EI) and ultrasonic imaging tools (UXPL) can be used to extract structures and pick up fractures with different opening degrees, effectively solving the problem of fine identification of bedding and fractures. This article also introduces the method of using non-conductive mud geological imaging (NGI) to identify fractures, and systematically analyzes the relationship between normal stress on the fracture surface, the angle between fracture direction and maximum principal stress, and production capacity. A quantitative standard for evaluating the effectiveness of oil-based mud fractures in the Kuqa Area is established. In practical applications, this set of crack fine identification of fracture and effectiveness evaluation methods effectively guides production operation measures and provides technical means for the evaluation and development of fractured tight oil and gas reservoirs.

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Differential Characteristics and Evolution of Conjugate Strike Slip Faults in the Halahatang Area, Northern Tarim Basin

CHEN Lixin, WANG Shenglei, WAN Xiaoguo, SU Zhou, MA Bingshan

Journal of Southwest Petroleum University(Science & Technology Edition) 2024, 46 (4): 19-37. DOI: 10.11885/j.issn.1674-5086.2023.11.17.01

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Non-classical X-type conjugate strike-slip faults are observed in the Halahatang Oilfield, which have obvious differences in zoning, stratification, segmentation and evolution characteristics, constraining oil and gas exploration and exploitation. Based on the 3 400 km$^2$ seismic data, this paper describes the stratification and segmentation characteristics of two strike-slip faults in NE direction and NW direction, and analyzes the differential evolution characteristics and mechanism. The results show that 1) from north to south, fault maturity and extensibility become weaker, and stress perturbation by NE-striking faults increased; from deep to shallow layers, the disturbance effect of NW-trending faults on NE-trending faults became weaker; deformation degree and maturity decreases upward in NW-striking faults, but increases in NE-striking faults. 2) Strike-slip fault underwent multiple evolution stages in Halahatang Area, which can be divided into Middle Ordovician conjugate fault formation stage, Carboniferous-Permian transtensional strike-slip fault reactivation stage, and Meso-Cenozoic transtensional strike-slip fault reactivation stage. The NE- and NW-striking faults had differential fault evolution process. 3) Mechanism of fault formation and reactivation changes during the evolution process. The strike-slip fault system during the Middle Ordovician is controlled by the superimposed deformation of pure shear and simple shear, and were also controlled by stress field, pre-existing structure and regional strata thickness. The reduction of stress from north to south and the change of associated stress field resultes in the difference of fault styles in the south and north.

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Hydrocarbon Accumulation Process and Multiphase Formation in the F$_{\rm{{Ⅱ}}}$21 Strike-slip Fault Zone of Tazhong Uplift

XIONG Chang, ZHAO Xingxing, WU Jiangyong, ZHANG Xinqiao, WANG Peng

Journal of Southwest Petroleum University(Science & Technology Edition) 2024, 46 (4): 1-18. DOI: 10.11885/j.issn.1674-5086.2024.02.29.06

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Aiming at the complicated phase distribution of Ordovician reservoirs in Fault F$_{\rm{{Ⅱ}}}$21 of Tazhong Uplift, we make a comprehensive analysis of tectonic analytical geochemistry, and find out that the plane distribution of oil and gas physical properties such as oil density, gas drying coefficient, gas oil ratio, etc. is closely related to strike-slip fault segment structure, that condensate gas reservoir develops in the north of the wing tail structure zone, and that volatile oil reservoir and crude oil reservoir develop successively in the south area. The crude oil in the F$_{\rm{{Ⅱ}}}$21 fault is the same as that of the northern depression Fuman and Shunbei areas, mainly from Lower Cambrian source rocks. The maturity of crude oil decreases from north to south along the fault zone. Natural gas in the north of the fault zone is mainly crude oil cracking gas, and in the central and southern parts mainly kerogen cracking gas. The Ordovician reservoir in the F$_{\rm{{Ⅱ}}}$21 fault zone underwent multi-stage oil and gas injection, and the wing tail graben site was a favorable filling point for oil and gas, and the strong charging and transformation of pre-salt crude oil cracking gas in the Himalayan period was an important reason for the formation of condensate gas reservoir in the northern part of the fault zone. Affected by the paleostructural, the oil resources generated in the Late Caledonian and Late Hercynian periods were mainly accumulated in the southern nose uplift area of the wing tail graben structure.

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Design of Combination Lifting Technology of Rod Pump and Ground Driving Screw Pump

YANG Zhi, KANG Lu, ZHANG Xinghua, CHEN Yong, YI Zhaolong

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 163-170. DOI: 10.11885/j.issn.1674-5086.2020.11.14.01

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Along with the development of deep oil and gas fields such as Tarim, satisfying the technology of deep and large pumping in deep well has gradually become a reality. The pump setting depth is deepening, the single way of lifting tend to show some limitations and inefficiency, so we propose a combination of lifting technique of sucker rod pump and ground driving screw pump: the screw pump and plunger pump being installed on the same production string, and the relaying way of extracting oil carried out. In order to demonstrate the feasibility of the lifting technique of rod pump and ground drive screw pump, we analyze the working principle, flow matching and force condition of the rod pump and ground drive screw pump, and establish the suspension load calculation model of the combined lifting process of the rod pump and the ground driving screw pump in the deep pumping conditions of the well. Compared with sucker rod pump, the swabbing parameters in the same production case of combination lifting system of sucker rod pump and ground driving screw pump will increase the depth of pump and the range of displacement, and reduce the energy consumption by reducing the polished rod load of the pumping unit.

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Drilling Fluid Technology for Gaoquan Anticlinal Wells in the Southern Margin of Junggar Basin

XU Shengjiang, WU Baocheng, XU Xinniu, YE Cheng, HUANG Hong

Journal of Southwest Petroleum University(Science & Technology Edition) 2023, 45 (3): 89-97. DOI: 10.11885/j.issn.1674-5086.2021.04.29.08

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In view of the characteristics of the strata encountered in drilling the Gaoquan structure in the southern margin of Junggar Basin, the technical difficulties in this area were proposed. We analyzed the drilled well data and mineral composition and mechanical characteristics and found problems like a narrow drilling safety density window and large surface-subsurface temperature difference. Combined with the field conditions, the drilling fluid systems adapted to upper strata and middle and lower strata respectively are given. We proposed that a strong inhibiting water-based system; a medium density and strong sealing oil-based drilling fluid system is applied to the hard and brittle mudstone formation of Taxihe Formation in the middle and lower strata; and oil-based drilling fluid system with low filtration loss is applied to strong water-sensitive formation of Anjihaihe Formation. The results show that the strong inhibiting water-based drilling fluid system can effectively prevent collapse and pipe stuck in the upper part of the Gaoquan anticline formation on the southern margin; the high-density oil-based drilling fluid used in the middle and lower part of the formation has excellent anti-collapse and anti-leakage performance, with a temperature resistance range of -10 ℃ to 240 ℃, and can resist up to 40% brine intrusion and 10% water-sensitive cuttings contamination. The drilling fluid technology provides important technical support for the major oil and gas discovery in the Gaoquan structure, and can be used as a reference for drilling fluid solutions for exploratory wells in similar areas and formations.

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A Study on Cement Slurry Circulation Fluid Mixing for Deep Well Casing Cementing in the Sichuan-Chongqing Area

YANG Fujie, SUN Jinfei, XU Kewei, LUO Hanlin, LI Zaoyuan

Journal of Southwest Petroleum University(Science & Technology Edition) 2024, 46 (4): 178-188. DOI: 10.11885/j.issn.1674-5086.2024.03.01.03

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During the process of cement injection in deep wells, due to the influence of complex wellbore conditions such as long sealing sections, narrow gaps, and high eccentricity, the annulus fluid is prone to mixing, and the mixing may increase the friction of the mixed section, causing cementing leakage. In order to solve the problem of inaccurate ECD prediction of high eccentricity annulus in the casing cementing operation of the oil layer in the Gaomo in eastern Sichuan, a cementing fluid mixing simulation and an experimental study on the rheology of the slurry were carried out. The study calculated the slurry in real time based on CFD. According to the changes in the fluid proportion of each section, the wellbore ECD was calculated by fitting the rheological equation through rheological experiments. The results proved that the eccentricity is the main factor affecting the change of the mixing ratio. When the eccentricity is low, the proportion of drilling fluid, spacer fluid and cement slurry is 5：1：4, and when the eccentricity is high, the ratio is mainly 7：1：2; the ECD of the mixed grout is 0.2$\sim$0.8 g/cm$^3$ higher than the conventional ECD in the upper grouting section, and is 0.2$\sim$0.5 g/cm$^3$ higher in the lower pure cement section. This study reveals the impact of complex well conditions in deep wells on the mixing ratio between fluids and the equivalent density of the wellbore. It is of great significance to ensure the safe cementing operation of deep wells in Sichuan and Chongqing and improve the quality of cementing.

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Journal of Southwest Petroleum University(Science & Technology Edition) 2024, 46 (4): 1-.

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