bluuebunny/crossref_metadata_2025 huggingface dataset:
Reservoir numerical simulation method considering time-varying relative permeability during polymer flooding process
Authors: Zhou Wensheng , Li Baozhen , Tang Engao , Zhang Jian , Yong Wei
Published: November 2024

In response to the abnormal decline in liquid production capacity during the middle and later stages of chemical flooding in Chinese offshore oil fields, in-depth analysis was conducted using reservoir engineering, dynamic analysis, and reservoir simulation methods. Because of the viscoelasticity of polymer solution, the relative permeability curve of oil/water during polymer flooding is different from that during water flooding, including the minimum mobile water saturation and residual oil saturation. In this study, an interpolation coefficient ‘f’ related to polymer solution concentration was firstly proposed for simplicity. Then, reservoir numerical simulation with the self-developed simulator ‘SIMFAST’ were conducted to investigate the influence of the interpolation coefficient ‘f’ on the injector and producer performance and the applications in actual field production history matching. The results indicated that compared with the commercial simulators, the self-developed simulator with the interpolation factor could more reliably describe the characteristic of the injected polymer solution in controlling water cut rise, and more efficiently simplify the combination of parameters on relative permeability curves during polymer flooding in offshore oilfields. Finally, above reservoir simulation method considering the change of the relative permeability curves during chemical flooding, was successfully conducted in the production history matching in J oilfield in Bohai Bay China, in terms of oil rate & water cut parameters. The research results give an efficient method to investigate the fluid seepage behaviour variation and its influence on oil rate and water cut during polymer flooding in China offshore reservoirs, which offers very useful technical support for the accurate design of chemical flooding schemes.
Research and Development of A Comprehensive Management Platform for Intelligent Production and Construction of the Entire Process of Sulige Gas Field
Authors: Yang Fu , Li Haoyu , Luo Liang , Wang Gang , Li Shoudong , Wu Jiahu
Published: November 2024

The Sulige gas field is the first fully installed atmospheric field in China with an annual production capacity exceeding 30 billion cubic meters. It has the characteristics of low permeability and density, rapid development decline, and large annual compensation decline workload. As a pilot project for the regional production and construction project system in Changqing Oilfield, Sulige Gas Field Development Branch is facing problems such as a wide range of project management points, limited personnel, difficulty in engineering data collection, and tight time connection between various professional businesses. By using digital and information technology, it has developed and created a closed-loop management platform for the digital production capacity construction of the entire business chain of production and construction project drilling, testing, and investment, and constructed a multi-dimensional visual control mechanism for the entire process of a single well, Realized digital management of the operation of a single account for the entire business chain production and construction project of drilling and trial investment; Relying on operator resources to quickly and low-cost expand the basic network, achieving real-time video monitoring of multi platform drilling and testing sites, collection of construction data, and online tracking; Establish a big data model for condition analysis and early warning, and innovate the formation of a “digital+safety dual prevention mechanism” linkage management and dynamic and static risk early warning push; Develop 16 APP functions such as supporting coordinates and well site handover to achieve online flow management of production and construction business, more efficiently guide production organization and close connection of processes, and significantly improve the efficiency of production and construction organization; Creating a dedicated digital and intelligent environment for production and construction, achieving deep integration of digital and intelligent business with Oil and gas fields production and construction, further enhancing project management and collaborative combat capabilities among various specialties. The innovative digital production capacity closed-loop management of Sulige Gas Field platform realizes the full lifecycle and multidisciplinary integrated management of wellbore engineering. Its efficient digital production organization model can provide a certain reference for the organization and management of similar projects in the upstream of exploration and development.
Research on the Recognition and Characterization of Fractures in Coal Rock Based on CT Scanning
Authors: Ye Zhilin , Qu Shiyuan , Liu Jianquan , Gao Xiang , Jin Yi
Published: November 2024

Coal rock fractures play a vital role as key channels for gas migration and storage in the exploration and development of coalbed methane. The characteristics of these fractures, such as porosity distribution, specific surface area, and connectivity, directly impact the adsorption, diffusion, and permeability behaviors of coal reservoirs. Therefore, a detailed analysis of coal rock fracture characteristics is vital in assessing the extractability of coalbed methane and during its exploration and development process. Currently, techniques like imaging logging, seismic detection, and micro-CT are employed for characterizing and studying fractures at various scales. Among these, high-resolution non-destructive CT scanning technology, by constructing three-dimensional data models of core samples, enables a quantitative analysis of fracture distribution features and size parameters. Traditional digital image processing methods, such as threshold segmentation and binary segmentation, though advantageous in computational speed, have limitations in the accuracy of fracture identification. With the advancement of artificial intelligence technology, deep learning-based image processing techniques have increasingly become significant tools for fracture detection due to their powerful feature extraction capabilities. This study conducted micrometer-level CT scanning experiments on coal rock samples, using CT image processing technology to construct a digitalized coal rock core model. Deep learning methods were applied for precise fracture identification, establishing an appropriate deep learning architecture and optimized parameters for coal rock fracture recognition. Furthermore, this paper provides a detailed quantitative characterization of the precisely identified fractures, offering robust technical support for the exploration and development of coalbed methane. The high-resolution non-destructive CT scanning technology and three-dimensional fracture network reconstruction method used in this study have been proven to be effective tools for investigating the micro-features of rocks, enabling the three-dimensional visualization and detailed characterization of rock microstructures.
Exploration and Practice of Treatment Technology for Casing Damage in Gas Wells
Authors: Wang Sifan
Published: November 2024

In order to solve the adverse effects of casing damage on potential exploration measures such as layer inspection and hole repair, repeated fracturing, and bridge plug fishing in gas wells, to prevent the problem of annular pressure, and to effectively ensure the safety production of gas wells, exploratory research on the treatment technology for casing damage in gas wells has been carried out. First, the principle of casing damage and the technical difficulties of treatment are systematically analyzed. Then, combined with auxiliary technologies such as casing cutting and milling, various technological processes were introduced, including cement squeeze sealing, chemical squeeze sealing, permanent annular sealing, casing patching, small casing wellbore reconstruction, and casing milling and squeeze sealing. Successfully tested on-site in over ten wells, a series of treatment technologies for gas well casing damage has been developed, providing a technical reference for the treatment of other gas wells with casing damage. Furthermore, in response to the challenges faced by the technology of gas well casing damage, new technical ideas and development directions have been proposed to promote continuous improvement in the low-cost and high-reliability aspects of gas well casing damage treatment technology.
Research Progress onLeak Prevention and Plugging Technology in Deepwater Drilling
Authors: Liu Jianquan , Kou Xiaobo , Liang Xu , Gao Xiang , Ye Zhilin , Jin Yi
Published: November 2024

With the continuous development of global oil and gas resources, onshore and shallow water crude oil production is no longer sufficient to meet the demand. Therefore, deepwater oil and gas exploration and development have attracted high attention from various countries. China’s oceans are vast and rich in offshore oil resources, especially in the South China Sea, where oil and natural gas reserves are enormous. In recent years, it has become a key focus of national offshore oil exploration and development. The increasing complexity of deep-sea well leakage in the ocean and the increasing difficulty of management have brought great challenges to drilling construction and also caused significant economic losses. Therefore, the research on leak prevention and plugging technology for deep water in the ocean has become particularly important. This article investigates the current research status of deep water leakage prevention and plugging technology both domestically and internationally, discusses the main problems that exist in the development and drilling process of deep water oil and gas fields, analyzes the reasons for well leakage, and proposes corresponding solutions.
Mechanism of Water Control and Gas Augmentation by Fracturing Interface Modifier in Water-bearing Gas Reservoir
Authors: Gong Furong , She Jiping , Ma Wenjing , Li Huimin , Teng Gege , Wang Yunfei , Zhang Shiyu
Published: November 2024

With the development of oil and gas reservoirs, water containing gas reservoirs have gradually received attention. However, problems such as water production during the production process have reduced gas permeability, leading to a decrease in gas well productivity underground. Phase permeability regulators improve productivity by changing the wettability of rocks and enhancing gas permeability. This article tests the interface performance of a phase permeability regulator and evaluates its temperature resistance, formation water salt resistance, and erosion resistance. The pore bound water saturation of the core before and after modification with the phase permeability regulator, as well as the relative permeability of gas and water phases, are tested. The experimental results show that the phase permeation regulator can reduce the surface tension of water to 22.2 mN/m, and the rock contact angle before and after soaking increases from 26.63 ° to 97.69 °, achieving the transition of rock from hydrophilic to hydrophobic. The surface tension of the phase permeation regulator changes significantly before and after aging at 80-120 °C, and its high-temperature resistance is poor. After mixing with formation water with a salinity of 60000 to 100000, the surface tension increases, and at a salinity of 60000, it increases by 5.1 mN/m. The use of phase permeability regulators for matrix core displacement resulted in a slight increase in displacement pressure, while the formation water remained unchanged after approximately 140 hours of erosion. After modification with phase permeability regulators, the irreducible water saturation of the core decreases by about 25%, and the relative permeability of the gas phase increases, resulting in a significant hydrophobic and gas conducting effect. Phase permeability regulators achieve hydrophobic gas conductivity by changing the wettability of rocks, which can alleviate the problem of water production in shallow and low salinity reservoirs.
Preparation and Performance Evaluation of Self-Degrading Temporary Plugging Agent for Well Workover of Fractured Reservoir
Authors: Ye Shuangxiang , Yang Yang , Wu Zhiming , Yang Jieyuan , Liang Kesheng
Published: November 2024

The temporary plugging technology is considered an important technology in the well workover process of oil and gas reservoirs. Gel is a frequently employed temporary plugging agent in oilfields; however, it has drawbacks, including poor cross-linking strength, unpredictable gelation duration, and considerable reservoir damage after application. To solve these issues, this study seeks to create a gel-based temporary plugging agent system that will improve the dependability and efficiency of oilfield development. In the study, acrylamide, hydrophobic monomers, initiators, crosslinkers, inorganic components, and scale inhibitors were used to formulate the temporary plugging agent. To close underground channels, the prepared plugging agent is injected into the underground and gels at high temperatures. In this study, the elastic modulus of the gel was investigated with a HAAKE rheometer, and the core flooding test was carried out to evaluate the plugging efficiency of the gel. Meanwhile, the visual code method was used to observe the formation time of the temporary plugging agent, and the self-degradation performance of the temporary plugging agent was studied. Hydrophobic monomers and inorganic materials significantly enhance the mechanical properties of the temporary plugging agent after forming the glue. The elastic modulus after crosslinking can reach about 450 Pa, and the maximum pressure of plugging can reach 2.4 MPa. The crosslinking time can be controlled within 30 minutes to 10 hours by adding the inhibitor. The crosslinking agent used in the system is ester organic matter, which can be hydrolyzed at high temperatures to achieve self-degradation performance, so that the degradation rate of the temporary plugging agent can reach 90% within 7 days after forming the glue. This temporary plugging agent has high strength, a controlled crosslinking time, and good self-degradation performance as compared to the typical gel-type temporary plugging agent. These qualities are crucial for reservoir protection and well workover.
Property Effect and Mechanism of Sodium Salicylate on Magnesium-based Curing Plugging Materials
Authors: Ma Wenjing , She Jiping , Wang Yunfei , Gong Furong , Li Huimin , Teng Gege , Zhang Shiyu
Published: November 2024

Lost circulation is a common problem in drilling and completion. Magnesium-based curing material has the advantages of effective plugging and formation damage control, and controlling curing time can extend the use. In this paper, the main agent of magnesium-based curing materials is magnesium salt, the influence of sodium salicylate with different dosage on the curing time in different curing states was analyzed, the optimal addition was determined, and the curing product and hydration process were analyzed under the optimal addition to determine the retarding effect of sodium salicylate. In static curing, the optimal addition of AR grade sodium salicylate was 15-17%, and the curing time was 3-4 h. The dynamic curing time at atmospheric pressure was obviously less than the static curing time, but clear right-angle thickening could be seen. The optimal addition of industrial grade sodium salicylate was 18%, and the static curing time was about 3 h. At high temperature and high pressure, it’s proved that pressure had little effect on curing time, but the curing time decreased significantly under high temperature environment. Through SEM, XRD and TGA, it was found that sodium salicylate was more conducive to the growth of the cured product, and more 517 phases was generated, but it did not affect the acid dissolution, with the acid dissolution rate reached more than 95%, which could realize the reservoir protection. By studying the hydration process, it’s showed that sodium salicylate could delay the hydration and reduce the heat release by about 2/3, and the hydration process was controlled by the phase boundary reaction. The retarding effect of sodium salicylate for magnesium-based curing material can guide the efficient application in different environments.
Integrity Management of Subsea Pipelines for Water and Gas Transportation in Offshore Gas Storage Facilities
Authors: Fan Jiaxi , Hao Dayong , Li Min , Wang Yong , Hu Caiyun , Wu Yingli
Published: November 2024

In the pilot test stage of N gas storage, relying on the construction of D oilfield, the injection production operation was achieved. The D355 subsea water transmission pipeline from the old A artificial island to the B artificial island was converted into a gas transmission pipeline. To ensure the safe and stable operation of the pipeline during the test stage, the feasibility was determined through verification and analysis of the pipeline; High consequence area identification and risk assessment have been carried out on the pipeline, and the risk level is within an acceptable range; Due to the lack of internal testing conditions, a comprehensive inspection and evaluation of the pipeline was conducted, including underwater magnetic memory non-destructive testing, external testing, and pressure testing; In response to the detected problem of exposed pipelines, concrete pads were used for interlocking treatment; In response to the scaling on the inner wall of the pipeline, conservative cleaning measures have been taken, including neutral immersion cleaning and non clogging cleaning with steel wire balls. After thorough argumentation, testing, and treatment, the pipeline has operated well after being put into operation, which is a successful practice for the integrity management of old submarine pipelines. It provides valuable integrity management experience for the gathering and transformation of various offshore oil and gas fields and the construction of offshore gas storage facilities.
Application of Real-Time Data Service Technology in Smart oilfield
Authors: Jianqin Yang , Xizhu Guan , Xiang Yue , Changmeng Xu
Published: November 2024

Real time data services play an important role in the construction of Smart oilfields, which can help oilfield production managers better understand the production situation and make more accurate decisions. Real time data services based on the Data Lake platform will bring more efficient and safer production methods to oil and gas fields, promoting the upgrading and sustainable development of the Smart oilfield industry. The technical architecture of Smart oilfield real-time data service mainly includes data lake platform, big data processing, edge computing and other core technologies. The data lake platform provides infrastructure, platform services and application services for Smart oilfield. Big data processing technology is responsible for rapid and accurate analysis of massive data. edge computing refers to computing at the data source to reduce data transmission and improve computing efficiency. The key technologies include data collection, transmission, storage, analysis, etc. Among them, data collection mainly uses sensors, PLCs and other equipment to collect production data. Data transmission uses technologies such as the Internet of Things and industrial Ethernet to transmit data to the data lake platform. Data storage adopts distributed storage technology to ensure the safety and reliability of data. Data analysis uses machine learning, deep learning and other technologies to analyze data, Provide decision support.
Study on the Law and Influencing Factors of Spontaneous Imbibition in Chang 7 Reservoir of Ordos Basin
Authors: Wang Xiaoxiang , Zhang Yang , Fan Xin , Zhou Desheng
Published: November 2024

This paper examines the imbibition and oil displacement process of fracturing fluid in a laboratory setting, focusing on the Chang 7 tight oil reservoir block in Ordos Basin. The study investigates the capability of different imbibition fluid systems to alter wettability and reduce interfacial tension. Additionally, it explores the imbibition and oil displacement abilities of cores with varying levels of wettability and permeability focusing on the imbibition equilibrium time, imbibition recovery rate, and the imbibition recovery multiplier. The reasons for these results were also examined. A multivariate nonlinear regression model is established to analyze the relationship between imbibition recovery, capillary radius, wettability angle, and interfacial tension. Additionally, neural network analysis is employed to determine the significance of these influencing factors. The findings from this research provide theoretical guidance for enhancing understanding of imbibition mechanisms and improving recovery rates in tight oil reservoirs.
Development and Application of Integrated Injection System for Injection and Profile Control in Dagang Oilfield
Authors: Wang Yingying , Yang Jijun , Zhang Yongtao , Huo Liaoyuan , Song Zuchang , Cao Xiaomei
Published: November 2024

Dagang Oilfield is a heterogeneous, multi-layered, and structurally complex fault block oil reservoir. During the production process, the contradictions between layers and within layers are becoming increasingly prominent. Split injection and profile control are two important development processes for ensuring production and increasing production in current oilfield development. However, during the construction process of split injection wells for profile control, there are often problems with plugging agents, which affect the effectiveness of split injection and the success rate of testing and adjustment, and even require well repair operations. This has become a key quality control production link that affects the efficiency of oil recovery construction and the improvement of quality, cost, and efficiency. The idea of developing a new type of integrated water distributor for injection and profile control has been proposed, which can achieve dual functions of layered water injection and profile control using a set of pipe columns. Through several years of technological breakthroughs, technological breakthroughs have been made in various aspects such as main structure design, anti backflow structure design, and water nozzle optimization design. Innovative proposals have been made and the integrated water distribution device structure design for injection and profile control has been successfully developed, fundamentally solving the pain points and difficulties of low measurement and adjustment rate after injection well profile control construction, significantly improving the qualification rate of measurement and adjustment, and significantly improving work efficiency and construction quality.
Experimental Study on High Conductivity and Slow Acid Fracturing in Deep Ultra-high Temperature Carbonate Reservoirs
Authors: Li Ce , Du Juan , Chen Pengfei , Xiong Gang , Liu Pingli
Published: November 2024

Acid fracturing is a commonly used method for increasing production and injection and transformation measure for carbonate reservoirs. However, deep carbonate reservoirs generally have high temperature and closure pressure, low maintenance of acid etched fracture conductivity after acid fracturing, and fast rate of production decline. The experimental study investigated the acid rock etching morphology and acid etched fracture conductivity of hydrochloric acid, gelling acid, authigenic acid, polymer-surfactant acid, and chelating acid when injected alone or alternately at 200 °C and optimized the optimal injection displacement and injection time for different acid solution systems. Experimental research has found that polymer-surfactant acid has the best non-uniform etching effect in a 200 °C environment, with the highest maintenance of acid etched crack conductivity. The non-uniform etching effect of chelating acid is poor, but its conductivity is maintained high under high closing pressure, and it can deepen the etching effect along existing etching cracks. The alternating injection of polymer surfactant acid and chelating acid will form grooved etching channels on the rock wall, which still have high conductivity after crack closure. The secondary alternating injection of polymer-surfactant acid and chelating acid can increase the conductivity of acid etched fractures by 60%. The recommended alternate injection of polymer-surfactant acid and chelating acid into acid fracturing can significantly improve the effectiveness of acid fracturing modification. This study provides new research directions and data support for the selection of acid fracturing working fluid systems in ultra-high temperature carbonate reservoirs.
Well control technology and digital intelligent management practice in Zhaodong Oilfield
Authors: Wang He-qiang , Ma Cui-yan , Guo Bing , Guo Hai-tao , Wang Zi-yu
Published: November 2024

Zhao-dong Oilfield is an offshore cooperation project in the mode of “international operation and PetroChina control”, adheres to the principle of “safety and environmental protection first, equal emphasis on production and efficiency”, practices the well control management concept of the whole life cycle, and consolidates the foundation of well control management by continuously optimizing the system and system, adheres to the integrated design of geology and engineering to control the source risk, implements fine trajectory control and anti-collision management to control the process risk, and The digital and intelligent production monitoring system is applied to control dynamic risks and realize the safe, efficient and sustainable development of Zhao-dong Oilfield.
Fatigue Life Analysis and Equal Life Optimization Design of Fluid End of Septuple Fracturing Pump
Authors: Wang Bo , Zhou Huan-hui , Zhao Chong-sheng , Huang Kun-peng , Cheng Ming-hao , Wu Qiang , Deng Jie , Xu Ji-duo
Published: November 2024

To determine the cause of failures phenomenon of fatigue cracks in the crossbore area of septuple fracturing pump 4 inch fluid end, optimal design the fluid end based on the idea of equal fatigue life to reduce non-uniformity and prolong fatigue life. Firstly, the static finite element analysis under 14 design conditions and 1 test condition are calculated, the results fulfill the static strength requirements. Next, based on the static of 14 actual working conditions, find cycle peaks through constant amplitude alternating load, the fatigue life and distribution rule were calculated. Then, increase the single side width increment e to 75mm, non-uniformity between 7 cylinders is reduced from 26.6% to 1.35%, the fatigue life is prolonged by 98.2%. Finally, by parameter optimization of the crossbore fillet radius Ru to 15mm and reducing the distance from the central axis of the suction cylinder to the top 25mm, the non-uniformity of the cylinder 4 is reduced from 20.07% to 7.67%, the fatigue life is prolonged by 40.9%, and it is prolonged by 179.4% totally. The results show that the analysis method by finding cycle peaks can accurately calculate the fluid end fatigue life. The equal fatigue life parameter optimization approach has obvious consult significance for reduce non-uniformity and prolong fatigue life of septuple fluid end.
Study on Production in Different Layers of Tight Reservoir
Authors: Zhao Shuangshuang
Published: November 2024

In rencent years, the tight oil blocks in our factory are all developed without injectio n and put into production by large-scale fracture network. There are problems of low initial pro duction and fast decline, and the development effect is poor. Because of the large inclination A ngle of the vertical well, it is impossible to obtain the test results of stratified fluid production b y conventional test methods. At the same time, the understanding of tight oil reservoir utilizatio n status after large-scale reconstruction is not clear enough. Therefore, the test of liquid product ion profile in inclined vertical Wells is explored. Meanwhile, the results of conventional liqui d production profile are applied to in-depth analysis of reservoir utilization status in convention al blocks and test blocks respectively, and the relationship between different reservoir types an d fracturing scale and liquid production capacity is determined. The influencing factors and app lication principles of CDFT test results were clarified, the understanding of different reservoi r utilization conditions was obtained, and the main direction of the optimal design of fracturin g program was clarified, which provided technical support for the subsequent design and optim ization of fracturing program in the new district.
Interwell channeling and sealing technology in Changqing CCUS block
Authors: Gao Guocheng , Yang Jinfeng , Wang Wenbin , Deng Kai , Xin Meng
Published: November 2024

In the Changqing Oilfield’s CCUS (Carbon Capture, Utilization, and Storage) project, a novel fracture-based inter-well gas migration sealing technology was developed to address the challenges of reduced production and even shutdown of oil and water wells due to inter-well migration. This was particularly crucial in the context of low fracture pressure-bearing capacity below 40 MPa, the absence of precedents in inter-well gas migration sealing techniques, and the difficulty in accurately estimating the fracture communication volume. The technology is grounded in multi-segment plug water blocking techniques, utilizing geological and well-network data to simulate the gas volume within fractures, thereby determining the precise quantity of plugging agent required. To meet the long-term sealing needs, the technology not only incorporates corrosion-resistant gel in the multi-segment plugs but also integrates water-dispersive cement slurry and CO2 corrosion-resistant cement slurry to enhance the durability of the seal. The injection parameters were optimized based on the pressure-bearing characteristics of the formation to prevent pressure leakage. Field tests indicated that the injection pressure increased by 4 MPa after the application of this technology. Despite the occurrence of gas migration during the plugging process, the close approximation between the designed injection volume of 350 cubic meters and the actual required volume of 326 cubic meters suggests that the technique could achieve its intended effectiveness with further adjustments. This technology provides new insights for handling similar inter-well migration issues in CCUS projects and serves as a reference for other similar endeavors.
Effect of Hydrate Saturation on Triaxial Shear Mechanical Properties of Methane Hydrate-Bearing Sediment
Authors: Sun Yuqi , Liu Li , Hui Chengyu , Zhang Yiqun , Ji Guodong
Published: November 2024

As a clean energy source, natural gas hydrate resources are essential to the development of energy in the twenty-first century. However, the degree of consolidation of the hydrate reservoir is low, and complex accidents such as wellbore instability, reservoir collapse, and gas production leakage will be caused if improperly exploited. The laboratory employs a self-developed triaxial shear test equipment that operates under high pressure and low temperature conditions. This equipment is specifically designed to determine the mechanical parameters and strength characteristics of methane hydrate bearing sediment (MHBS) samples. It is used to create water-saturated hydrate deposits with varying levels of saturation. The synthesis of MHBS samples with varying saturations is achieved by precisely regulating the amount of water. The saturation of MHBS is then determined and confirmed by the utilization of the “water content method” and the “gas collection method.” Triaxial shear tests are conducted on MHBS to examine the impact of hydrate saturation on the mechanical parameters and strength behaviours of MHBS. The experimental findings demonstrate that the presence of hydrate crystals enhances the robustness of the depositing medium. The stress-strain curves of MHBS have a hyperbolic shape, indicating strain hardening features. The stress-strain curves may be categorized into three distinct stages: the initial elastic deformation, followed by a slow shift to the initial yield deformation, and ultimately leading to strain hardening. As axial strain rises, the behaviour of the MHBS transitions progressively from elastic deformation to plastic deformation. The shear strength and initial yield strength of MHBS enhance with higher hydrate saturation. The reason for this is that as the hydrate saturation rises, the influence of hydrate crystals on the enhancement of sediment strength becomes more pronounced. However, the initial yield strain of each MHBS sample is between 0.5% and 1.5%, and the difference is not significant. When the hydrate saturation rises gradually, the cohesion of MHBS enhances. Nevertheless, the hydrate saturation has a very minor impact on the internal friction angle.
Controlling Factors of Dissolution Pores in Zeolite Cements of Permian Clastic Rocks in Northwest of Junggar Basin
Authors: Guo Mozhen , Ni Xinfeng
Published: November 2024

Zeolite cement dissolution pores, buried at a depth of over 3600 meters, are found well developed in clastic rocks of Permian in northwest of Junggar basin. Studying the controlling factors of zeolite cement dissolution pores have important meaning to predict the distribution of favorable reservoirs in deep oil and gas exploration of Permian. A comprehensive research method of thin slice analysis of 800 pieces of castings from 60 wells, core observation, scanning electron microscopy, and clay mineral analysis was adopted. It is believed that the dissolution pores of zeolite cements are mainly controlled by zeolite distribution, the scale and range of inorganic and organic acids. Firstly, different zeolite cement types appear a regular pattern that control dissolution pore types and their distribution scope. The study area are well developed three types zeolite cements: heulandite, analcite and laumontite. The heulandite cements are developed in basin edge, showing a belt-like distribution, and then the analcite distribution area. laumontite cements are distributed in basin central. Horizontally in basin edge, reservoir pore type is primary intergranular pore, and followed by analcite dissolution pore. In central basin, the major pore type is laumonitite dissolution pore, and followed by primary intergranular pore. No heulandite dissolution pores are found in study area. Secondly, analcite dissolution pores, formed by inorganic acid and distributed in basin edge, are controlled by the scale of stratigraphic unconformities and faults. Laumonitite dissolution pores, formed by organic acid and developed in central basin, are controlled by the scope of source rock. Thirdly, it is proposed that the meddle-belt of basin is the favorable zone for Permian reservoirs because it is located fan delta front where the laumontite cement is developed, close to the source rock, and in the updip direction of the three stages of organic acid migration. It is considered that central basin has favorable conditions to form laumontite dissolution pores, and pointed out that this zone is a favorable zone for the development of deep reservoirs in the Permian.
Enhanced Oil Recovery Technology in High-Temperature Shale Oil Reservoirs: A Review
Authors: Li Qi , Wang Xiaoyan , Ge Hongjiang , Li Dongping , Zhang Yang , Yang Weihua
Published: November 2024

As a strategic continuation resource, shale oil has abundant reserves and significant development potential, with the decrease of conventional oil and gas resources. However, in contrast to North American marine shale oil, China’s shale oil is mostly continental, has high reservoir heterogeneity, ultra-low permeability and porosity, and the oil recovery is generally lower than 10%. In this review, the advances in laboratory research and field application of enhanced oil recovery (EOR) technologies such as gas injection, agent injection and nanomaterial injection in high-temperature shale reservoirs are systematically reviewed, and the mechanisms of various technologies are also explained, as well as their advantages and disadvantages. In particular, the problems and challenges faced by EOR are thoroughly analyzed, and suggestions and strategies for the efficient development of shale oil are proposed. Gas injection is an effective method to supplement formation energy in shale reservoirs, which can effectively enhance shale oil production, but there are problems with gas sources, gas channeling and corrosion. At present, injection agents and nanomaterials are still in the laboratory research stage and have not formed large-scale applications in shale reservoirs. In the future, it will be important to thoroughly research the interface impact of various injection medium and oil-water-shale, clarify the applicability of shale oil EOR technologies, accelerate the key test of shale oil stimulation technology, and help scale benefit development and high-quality development of shale oil.
Drilling Technology of Large Plumb Ratio Shallow Shale Gas Well
Authors: Wang Bo , Zang Xiangmei , Wang Xuanchao
Published: November 2024

SY1H is the first shallow shale horizontal well deployed in Jilin Oilfield, with a depth of 1,150m in Qing1 section of the target layer, a designed horizontal section length of 2,000m, and a water-drag ratio of nearly 2:1, so the well is characterised by the difficulty of pressurising with a large digit-drag ratio, the high friction between the drilling and the lower casing, and the shale wall being easy to be destabilised and collapsed. There are no horizontal wells in the neighbouring wells with a section of green as the destination layer, and there is a lack of reference materials, and the stability of the shallow shale is not clear. In order to ensure that the well can be reached and drilled for a long time, a technical route was formulated with the objectives of effectively reducing drilling resistance, increasing drilling pressure, and rapid drilling and completion within the collapse cycle, and technical measures such as equipping with a top drive and a high-grade drilling rig to increase the drilling pressure, oil-based drilling fluids and rotary guiding to reduce drilling resistance and the ability to deal with complex situations, and floating casing process to ensure that casing can be smoothly lowered in place, etc., so as to achieve safe and rapid construction of SY1H and achieve a horizontal section of 2,000m. construction and achieve the geological target of 2000m horizontal section.
Research and Application of Smart Temporary Plugging Gel for Small Casing Cementing in Changqing Oilfield
Authors: Zhang Yan , Wan Xiangchen , Min Jiangben , Li Siyang , Li Peng , Li Yancheng
Published: November 2024

In response to the serious leakage and low productivity recovery rate after cement plugging during the secondary cementing process of repairing small casing in the old wells of Changqing Oilfield, this study draws on the theory of shielding and temporary plugging in the drilling process to propose an adaptive smart temporary plugging gel technology. This technology has developed a weak gel suspension base liquid and synthesized a polymer material with good viscosity, high deformability, high sealing strength, and the ability to automatically hydrate and degrade at a certain temperature. It synergistically cooperates with other auxiliary temporary plugging materials to form an adaptive and self-degrading temporary plugging gel system, which can quickly form a sealing barrier at severely leaking areas such as corroded perforations, effectively preventing cement slurry leakage during subsequent cementing processes, shortening the operation cycle, and protecting the reservoir. Experimental evaluations indicate that the gel system can withstand pressure up to 15MPa, degrades in 7-10 days, and achieves a reservoir recovery rate of over 90%, effectively achieving the goals of plugging, releasing, and minimizing reservoir pollution. It has been applied in 30 wells in the Changqing Oilfield, with a success rate of over 96% in the first plugging operation, and an average production recovery rate of over 95%, significantly protecting the oil reservoir.
Study on the Percolation Law of Tight Gas in the Western Sulige Area based on the Lattice Boltzmann method
Authors: Xie Yang , Wang Chunpu , Gao Xiaomian
Published: November 2024

To address the problem of unable to determine the percolation law of tight sandstone gas reservoirs under laboratory conditions, especially when there are no water production measurements and no obvious edge and bottom water. In this study, takes the Western Sulige area as the research object, and based on the geological characteristics of the Western Sulige area and the lattice Boltzmann method, establishes a LB mechanism model for tight gsa in the Western Sulige area, identify Identify fluid distribution and percolation rules in the pore throat structure of Western Sulige area The results show that There are four types of bound water in the pore throats of the western Sulige area, including trapped water, bind pore water, dead pore water, and liquid film.. The remaining gas in the production process is mainly distributed in the pore throat structure, including bind pore gas, fine throat pore gas, and water seal gas. In the early stage of gas-water production, formation water mainly in the form of liquid film reduces the cross-section of natural gas flow. Subsequently, formation water mainly in the form of liquid droplets clogs the throat, thereby reducing the gas percolation capacity. Due to the capillary suction effect, liquid–solid viscous forces, and pore–throat structures, the reservoirs of Western Sulige Area is prone to water lock damage, resulting in reduced production and even production suspension of gas wells. Therefore hydraulic fracturing is a necessary measure for the development of tight gas, but the increase in the intensity of fracturing operations has increased the width of fractures and strengthened the water lock phenomenon, further worsening the percolation capacity of the matrix.
Formation pressure prediction method based on machine learning
Authors: Zhang Zhen , Yan Chuanliang , Cheng Yuanfang , Han Zhongying , Wu Sini
Published: November 2024

Formation pore pressure is one of the key parameters in petroleum engineering. The high-temperature and high-pressure working conditions formed under the complex mechanism of Yingqiong Basin make downhole complex events such as overflow and well leakage occur frequently. To address the problem of the large prediction error of the traditional Eaton method under high temperature and high-pressure conditions, three machine learning methods, such as GA-BP(Genetic Algorithm-Back Propagation Neural Network), PSO-LSTM(Particle Swarm Optimization-Long Short-Term Memory Neural Network), SVR(Support Vector Regression), are introduced to find the nonlinear relationship between logging parameters and formation pore pressure. Seven logging parameters such as formation depth, mechanical drilling speed, drilling pressure, and rotational speed were used as input variables, and formation pore pressure was used as an output variable through correlation analysis for constructing the machine learning model. By analyzing the experimental results of the above three machine learning models with the Eaton method, the GA-BP model with lower error and more satisfying the needs of drilling engineering is preferred, and the various regression evaluation indexes of the model are also more excellent compared with other machine learning models, which are Mean Squared Error (MSE)=0.001, Mean Absolute Error (MAE)=0.003, and R-squared (R2)=0.991, respectively. It is concluded that the machine learning method is not only more advantageous in a class of nonlinear regression problems such as formation pore pressure prediction, but also can help engineers to predict formation pore pressure more accurately under the conditions of deep high-temperature, high-pressure, and complex formations, which contributes to guaranteeing the safety and high efficiency of drilling projects.
Quantitative Evaluation of “Four Qualities” in Deep CBM Using Logging Data
Authors: Yan Ping , Li Zhongbai , Yu Hongguo , Hu Gang , Feng Lixiang , Chen Jiayu , Gao Yanning , Du Xin , Wang Wei , Wang Deqiang
Published: November 2024

The four qualities of deep CBM (CBM resources buried depth greater than 2000 m), including coal rock quality, reservoir quality, well completion quality, and coal seam roof and floor quality, are important factors that determine the degree of coal rock gas enrichment, preservation conditions, and effective mining. Taking the deep CBM in the Ordos Basin as the research object, based on coal core experiments, sensitive logging information research on the “four qualities” key parameters of coal rock reservoirs is carried out, and a quantitative logging evaluation method for key reservoir parameters is established to provide support for the comprehensive evaluation of deep CBM. Coal rock quality parameters include macroscopic coal rock type, coal industrial components, coal macerals, coal structure, etc. The key parameters of reservoir quality include coal rock porosity, permeability, and gas content. The key parameters of well completion quality include rock mechanics parameters, stress and fracture pressure. The parameters of coal seam roof and floor quality include comprehensive evaluation of the lithology, stability, and sealing ability. By delving into the “four qualities” of deep CBM in logging data, combined with drilling, mud logging, coal core analysis and laboratory data, and using corresponding quantitative evaluation methods for logging, we aim to provide logging technical support for the optimization of favorable target areas for deep CBM exploration, single well fracturing layer selection, and reserve calculation.
Calculation of the Critical Liquid Production of Cyclic Steam Stimulation in Heavy Oil Reservoir with Edge Water
Authors: Zheng Wenqian , Liu Dong , Liu Xiaohong , Geng Zhigang , Miao Feifei
Published: November 2024

For heavy oil reservoirs with edge water, when the liquid production of cyclic steam stimulation is excessively high, there is a risk of edge-water invasion. Therefore, the liquid production of cyclic steam stimulation is of great significance to the prevention of edge-water invasion in heavy oil reservoir with edge water. Currently, many studies on the critical liquid production in oil reservoir by water flooding are conducted. However, there is few research on the critical liquid production in heavy oil reservoir by cyclic steam stimulation. To fill this gap, The formation after cyclic steam stimulation is divided into the heated zone and the unheated zone. A characterization method for the flow field parameters after cyclic steam stimulation is established. By transforming the length of the thermal swept zone, the comprehensive mobility of the heated zone is equivalently represented as the comprehensive mobility of the unheated zone. On this basis, considering the threshold pressure gradient in heavy oil, a calculation method for the critical liquid production after cyclic steam stimulation in oil reservoir is developed based on the theory of mirror reflection and the superposition of potentials. The results show: (1) Permeability being constant, the critical liquid production rate increases with the increase in cyclic steam injection quality. With a constant cyclic steam injection quality, the critical liquid production rate increases with the increase in permeability; (2) Guided by the established relationship curve diagram between critical liquid production and crude oil mobility, the development plan is designed. As a result, the comprehensive water cut in the oilfield is 8.1%, and no water invasion has occurred; (3) Guided by the established relationship curve diagram between the cumulative liquid production and cumulative heat injection corresponding to different critical liquid production rates, adjustments were made to the oilfield development plan. As a result, the critical liquid production rate for well A1 increased from 110 t/d in the first cycle to 150 t/d in the second cycle.