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05 March 2025, Volume 21 Issue 1

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OIL AND GAS EXPLORATION

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Application and Prospect of LiDAR Technology in Seismic Acquisition of Complex Mountainous Areas#br#

XU Wenrui , WANG Liye , WEI Chencheng , QIN Xin , LIU Yiyan , PENG Xiao

2025, 21(1):  1-9.  DOI: 10.12388/j.issn.1673-2677.2025.01.001

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The southern piedmont belt of Junggar Basin is rich in oil and gas resources. However，seismic exploration is faced with such problems as high implementation difficulties，low efficiency，high risks and high costs of field acquisition，due to the highly undulating surface conditions and complex underground structures. Therefore，the LiDAR technology was introduced to improve quality and efficiency in seismic acquisition. The functions of mountain excitation type division，mountain shot point pre-design，fine surface survey design，mountain vehicle navigation design and risk classification can be rapidly completed through the "far-looking" functionality of LiDAR images and high precision elevation data. With the application of this technology in mountain seismic acquisition，vibroseis has access into mountains，which effectively improves the excitation ratio of vibroseis in mountainous areas and the efficiency of field acquisition operations to improve quality and efficiency in the field. Looking ahead，it is believed that the LiDAR technology will play a greater role in seismic acquisition operations in complex mountainous areas. The high precision coordinates and elevation models of LiDAR images are expected to replace traditional measurement processes in field acquisition. The high resolution coordinates and elevations can improve the accuracy of surface modeling inversion. Rapid construction of digital outcrop models can be delivered with high definition imaging and digital elevation platforms. This technology promotes the upgrading of seismic exploration processes，the implementation of efficient exploration in mountainous areas，and data improvement for complex moutainous structures.

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Research and Application Status of Plugging Materials for Drilling Fluid

QIAO Mu, , ZHU Zhongxi, , YAN Kangkai,

2025, 21(1):  10-23.  DOI: 10.12388/j.issn.1673-2677.2025.01.002

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Lost circulation is a common and challenging downhole complex issue in current drilling operations. It has become one of the major factors affecting drilling speed and may lead to safety incidents of different levels. By comprehensively analyzing the types and mechanisms of lost circulation，the performances of global novel plugging materials under different operating conditions，and their interactions with factors such as the wellbore and formations，this study elucidates the characteristics and mechanisms of cement，cross-linking system and metallic plugging materials，granular and fiber lost circulation materials （LCMs），and the combination of curable materials and LCMs. The application performances and pros and cons of different types of LCMs for lost circulation in various formations are summarized. The results indicate that given both the treatment success rate and cost-effectiveness，cement plugging materials are preferred for handling fluid loss caused by the highly permeable rock matrix，with a treatment success rate of 91%. To address the karst-cavern thief zone，curable materials with LCMs are relatively favored，delivering a treatment success rate of 89%. Fiber LCMs are preferred for treating natural fracture-type lost circulation，with a treatment success rate of 75%. When dealing with the induced fracture-type lost circulation，granular LCMs are favorable，with a treatment success rate of 92%. The findings of this research are of important theoretical and technical guiding significance for enhancing the plugging performance of drilling fluids and promoting the development of lost circulation plugging technology.

OIL AND GAS DEVELOPMENT

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Hydraulic Filtrate Waste Recycling Technology for Water-Based Drilling Fluids in Longdong Oil Block#br#

SHAO Bin , LUO Pingya, , LAN Jun , LIU Lu, , CHANG Junli , YANG Zhen,

2025, 21(1):  24-31.  DOI: 10.12388/j.issn.1673-2677.2025.01.003

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Longdong Oil Block requires the full implementation of drilling fluid non-landing technology to promote the recycling of waste drilling fluid. In order to solve the problem that the performance of water-based drilling fluids prepared using on-site hydraulic filtrate waste cannot meet the standards and the influencing factors are not clear，the ethylene diamine tetraacetic acid（EDTA） titration，bacterial plate counting method and atomic absorption spectrometry （AAS） were used to investigate the key techniques to improve the reuse rate of hydraulic filtrate waste. The experiments show that the high content of calcium and magnesium ions，bacteria，and heavy metals are the main reasons for the poor performance of water-based drilling fluids prepared using hydraulic filtrate waste. Correspondingly，the modified coagulation and precipitation complexing agent II，polyether demulsifier JX，and flocculants ZY-I，ZY-II have been developed to perform the flocculation-precipitation-sterilization treatment together with the sterilizing agent. The resultant average removal rate of calcium and magnesium ions is 95.5%，the sterilization rates of saprophytic bacteria （TGB） and sulfate-reducing bacteria （SRB） are 96.54% and 100% respectively，and the heavy metal content is less than 2.31 μg/L. The laboratory tests of recycling of hydraulic filtrate waste and water-based drilling fluid preparation have been completed for 6 wells in Longdong Oil Block. Longdong Oil Block waste drilling fluid hydraulic filtrate recycling technology has been formed and applied in 5 wells of this block. The water-based drilling fluids prepared using the recycled hydraulic filtrate waste presents a performance in line with the drilling engineering design requirements，facilitating the smooth drilling process，effectively protecting the environment and saved water resources，demonstrating good prospects for application promotion.

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Oil-Based Drilling Fluid Anti-Collapse Technology for Long Openhole Wellbore of Jimsar Shale Oil#br#

WU Yicheng, LIU Peng, CAO Qingtian, CHANG Huipan, LI Shuai, ZHANG Bin

2025, 21(1):  32-40.  DOI: 10.12388/j.issn.1673-2677.2025.01.004

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The horizontal well of Jimsar shale oil with a long openhole wellbore adopts the two-casing-section structure，and the openhole wellbore of the second casing section is 4 000 m long，with a horizontal wellbore over 2 000 m. The used drilling fluids are oil-based，and wellbore collapse tends to occur when drilling the Badaowan and Jiucaiyuanzi Formations and leads to movement resistance，sticking of tools，lost circulation，etc. To overcome the wellbore collapse in complex formations，in accordance with the lithological characteristics of formations，the main factors affecting wellbore stability such as clay mineral composition and micro-fracture development were analyzed，the mechanisms of wellbore instability of such collapse-prone formations were clarified，and the anti-collapse theory of oil-based drilling fluids was developed，which features "multi-element cooperation and broad-spectrum plugging". Based on the proposed theory，the anti-collapse formulation of oil-based drilling fluids was improved by optimizing the materials such as asphalt products，ultra-fine calcium carbonates and nano-plugging agents. The laboratory tests show that the performance parameters of the drilling fluids meet the operation requirements and the plugging performance is excellent. Specifically，the drilling fluid density is 1.52-1.62 g/cm³；funnel viscosity，80-100 s；yield point，8-13 Pa；emulsion-breaking voltage，above 500 V；oil-water ratio，（80：20） to （85：15）；API fluid loss，≤ 1.5 mL；HTHP fluid loss at 120°C，≤ 2 mL. The presented anti-collapse system of oil-based drilling fluids has been successfully applied to Jimsar shale oil horizontal wells with a long openhole wellbore. The average borehole enlargement rate of the openhole wellbore and the rate of downhole complex issues were 3.03% and 0.55% respectively. The anti-collapse system effectively ensured the drilling safety of the build-up and horizontal wellbores.

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The Diffusion Law of Salt Ions in Shale Reservoirs and Its Application in Hydraulic Fracture Network Diagnostics#br#

LIU Zhenjun , ZHANG Yanjun , LIAO Wanrong , YANG Bing , YANG Liu , ZHOU Desheng

2025, 21(1):  41-49.  DOI: 10.12388/j.issn.1673-2677.2025.01.005

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Shale reservoirs are characterized by low porosity，low permeability，and difficulty in exploitation，typically requiring the development approach combining long horizontal wells with large-scale volume fracturing techniques. After the fracturing fluid enters the formation，it undergoes a series of physical and chemical reactions with the reservoir，where salt ion diffusion plays a significant role. However，the existing research on the mechanism of ion diffusion and its application to diagnosing hydraulic fracture network is still imperfect. Therefore，this paper combines theoretical analysis with field cases to summarize the sources of salt ions in shale reservoirs，and the characteristics，mechanisms and influencing factors of ion diffusion，and presents an example of diagnosing hydraulic fracture network based on salt ion diffusion. The sources of salt ions in shale reservoirs include dissolved salts in the water film on the pore walls，crystallized salts from hydrocarbon generation and water expulsion，and salts produced by water-rock interactions. The characteristics of ion diffusion are similar to the imbibition process，which is divided into three stages：initial，transitional，and late diffusion. The initial ion diffusion rate is relatively high，exhibits a linear relationship on a logarithmic time scale，and follows Fick's law and the Einstein-Smoluchowski equation. The factors affecting salt ion diffusion include reservoir properties，solution properties，and other factors such as temperature and viscosity. Saltion diffusion can be used for the diagnosis of the development degree of volume fracturing fracture network. The method of diagnosing hydraulic fracture network through salt ion diffusion can provide scientific guidance for shale reservoir fracturing design and fracture network evaluation，help to deliver more accurate and effective reservoir stimulation and promote the efficient development and utilization of shale oil and gas resources.

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Research Progress on the Mechanisms and Control Methods of Casing Deformation in Shale Gas Horizontal Wells#br#

YIN Aobo , LI Jun, , LIAN Wei , ZHANG Hui

2025, 21(1):  50-60.  DOI: 10.12388/j.issn.1673-2677.2025.01.006

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Significant casing deformation （CD） occurs during multi-stage fracturing of shale gas horizontal wells，which reduces the ratio of recovered reservoirs and increases operation costs. Based on a comprehensive review of global research on this issue，a comparative analysis of the current status of casing deformation in shale gas horizontal wells was conducted. With the casing deformation data from Changning-Weiyuan，Luzhou，and Weirong blocks，the distribution patterns of casing deformation in terms of time，space，and morphology were summarized. The influences of engineering factors such as casing and cement sheath types，cementing quality，fracturing and perforation parameters，and thermal stresses，as well as geological factors such as reservoir heterogeneity and reservoir slip，on casing deformation，were analyzed. The analysis results indicate that while engineering factors can increase casing stresses，they are unlikely to cause casing deformation. Among geological factors，reservoir slip induced by natural fractures and faults activated during multi-stage fracturing is the main controlling factor leading to significant casing deformation. To address this issue，various control methods were summarized，including optimizing casing and cement sheath parameters，improving cementing quality，selecting appropriate fracturing and perforation parameters，optimizing wellbore trajectory，and controlling reservoir slip. Additionally，it was proposed to enhance the understanding of formations and improve prediction accuracy of reservoir slip. The research findings provide references for casing integrity design and control during the fracturing process.

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Prediction Method and Prevention Measures for Casing Deformation of Horizontal Well in Volume Fracturing#br#

.Oil Production Technology Research Institute, PetroChina Xinjiang Oilfield Company, Karamay , Xinjiang, China, .Downhole Operation Company, CNPC Western Drilling Engineering Co., Ltd., Karamay , Xinjiang, China

2025, 21(1):  61-68.  DOI: 10.12388/j.issn.1673-2677.2025.01.007

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Horizontal well volume fracturing has become a key technology for well completion and reservoir stimulation of tight oil reservoirs. For reservoirs with well-developed natural fractures and faults，high-intensity reservoir stimulation greatly increases the probability of artificial fracture-induced fault sliding，leading to casing deformation. To avoid hydraulic fracturing-induced fault sliding which could lead to shear deformation of casing，numerical simulation was used as a means to study the prediction method and prevention measures of casing deformation risk points. The H well group was taken as a field example in this research，and based on the integrated geological-engineering model and ant body tracking technology，the risk points of casing deformation were determined. With Mohr-Coulomb criterion and fracturing parameter optimization，the risk points of casing deformation were efficiently controlled，with effective preventive measures. The research results indicate that the integrated geological-engineering model and ant body tracking technology can effectively identify faults and natural fractures intersected by the well trajectories，and 20 risk points of casing deformation are predicted for the H well group. The threshold of fault activation sliding pressure was determined to be 70 MPa as per the Mohr-Coulomb criterion. The volume fracturing treatment of the H well group was carried out in a way following the strategy of "unaligned perforation + reduced pump rates + reduced injected water volumes"，and no casing deformation occurred during the fracturing operation process. A risk point prediction and prevention technology for casing deformation has been developed，effectively ensuring the safety of horizontal well volume fracturing opertation and improving the efficiency of reservoir stimulation，and providing technical references for the research on casing deformation prediction and prevention measures.

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Research on Oil Stabilization and Water Control Performance of Relative Permeability Regulator Grafted Proppant#br#

ZHANG Wei, , WEN Xuejun , PU Di , LUO Pingya , GUO Yongjun, , XIONG Qiyong

2025, 21(1):  69-77.  DOI: 10.12388/j.issn.1673-2677.2025.01.008

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In a certain area of Karamay Oilfield，numerous production wells suffer from rapid water cut rise and high water cut after fracturing treatments. To solve this problem，the proppant grafted with the hydrophobic association relative permeability regulator，RPM-SiO₂，was developed by grafting the hydrophobic association relative permeability regulator onto the quartz sand surface，with the help of silane coupling agents KH570. The grafting of relative permeability regulators onto the proppant surface was confirmed successful by infrared spectroscopy and electron scanning microscopy （SEM）. Under the reservoir conditions of the study area of Karamay Oilfield，the differences of conventional performance （wettability，density，acid solubility and compressive strength），fracture conductivity，and water control ability between RPM-SiO₂ and blank quartz sand proppants were investigated. The results show that the comprehensive performances of RPM-SiO₂ and quartz sands are basically consistent，both meeting the requirements of the industrial standard. The resultant oil phase fracture conductivities are consistent，but the water phase fracture conductivity of RPM-SiO₂ is 25% lower than that of quartz sands. Compared with quartz sands，RPM-SiO₂ presents a decrease of 83.41% in the water phase permeability，17.49% in the oil phse permeability，and 18.65% in the water cut of produced liquid. RPM-SiO₂ has high water control capability and long-term effectiveness.

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Development and Performance Evaluation of a High-Efficiency Asphalt Dispersant

ZHENG Cunchuan , WANG Wei , CHEN Shengen , WANG Rui , CHEN Jiangdong

2025, 21(1):  78-86.  DOI: 10.12388/j.issn.1673-2677.2025.01.009

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In order to solve the problem of severe blockage caused by the gradual precipitation，aggregation and settlement of asphaltenes with the decreasing temperature during the artificial lifting process in Tahe Oilfield，a high-efficiency asphalt dispersant was developed and evaluated via the steel wire mesh dissolution method. Through the characterization analysis of the wellbore sediments by three-component solvent fractionation，elemental composition determination and scanning electron microscopy （SEM），asphaltenes were determined to be the main component of Tahe wellbore sediments. According to the principle of similar mutual solubility ，a dispersant LYH-1 （aromatic solvent LY + 1.0% n-pentanol + 1.0% nonylphenol + 0.2% petroleum sulfonate） that could efficiently dissolve asphaltenes was developed. The asphaltene sediments were soaked in the asphalt dispersant LYH-1 in a water bath at 50°C for 4 h，and the solubility of 1 g of asphaltene sediments in 5 g of asphalt dispersant LYH-1 was as high as 97%，and the sediments did not aggregate after long-term standing，suggesting excellent stability and expanded applicability. The investigation of the working mechanism of the high-efficiency asphalt dispersant LYH-1 demonstrates that the dispersant forms a stable system with asphaltene sediments，mainly through hydrogen bonding and π-π interaction，which reduces the particle sizes of asphaltene aggregates to allow them to be stably suspended in solutions，and hinders the further flocculation and deposition of asphaltenes. The results show that LYH-1，as a novel high-performance asphalt dispersant，can effectively prevent the blockage of oil wells and surface pipelines while reducing production costs，so as to achieve the goal of production growth and improve the development efficiency of heavy oil reservoirs.

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Research Progress on Mechanical Composite Piping Technology for Oil and Gas Field Gathering and Transportation#br#

ZENG Dezhi , SHI Shengyao , LI Yiyang , SUN Jianghe , SU Rigu , CHEN Siyu

2025, 21(1):  87-94.  DOI: 10.12388/j.issn.1673-2677.2025.01.010

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Bimetallic composite piping technology is an important method to solve the internal corrosion of pipelines of the gathering and transportation system of oil and gas fields. The forming，welding and testing are the prerequisites for safe pipeline operations. To ensure the safe production of oil and gas fields，the progress of the forming，welding and non-destructive testing （NDT） technologies of bimetallic mechanical composite piping was reviewed. Two commonly used mechanical molding methods and their characteristics were clarified，the process methods for improving the quality of welded joints were analyzed，and the NDT technologies for different pipeline defects were summarized. The results show that in terms of pipe forming，explosive forming and hydraulic forming are commonly used in China for composite piping，but they still have limitations in manufacturing large-diameter pipes and special-shaped pipe fittings；in terms of welding，the quality of welded joints can be improved by optimizing the welding process，and the laser cladding technology of pipe ends has become a future research direction；in terms of the NDT，traditional testing methods are gradually developing towards intelligent and integrated modern technologies，delivering a wider coverage and higher defect detection rates. In addition，if the pipe end measurements at key steps of the full life cycle of mechanical composite piping are recorded，accurate traceability can be achieved once quality problems occur. It is concluded that improving the quality control of mechanical composite piping technology during the forming and welding processes and the accuracy of the NDT technologies is of great significance for their applications in oil and gas field gathering and transportation.