bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study on Oil-Gas Interface Stability Mechanism and Control Method of Gas-Assisted Gravity Drainage
Authors: Chen Xiaolong
Published: November 2024

The stability of oil-gas interface is an important factor affecting the recovery of the gas-assisted gravity drainage (GAGD). In this paper, the interface morphology characteristics of GAGD in porous media under 8 flow rates and 3 displacement dip angles were studied by using a visual physical model. The non-dimensional parameters such as capillary number and bond number were introduced to qualitatively characterize the oil gas interface morphology, and the process of gas invading the pore throat of porous media under different interface morphologies was revealed. The fractal dimension is employed for quantitative characterization of the morphology of the oil gas interface during the GAGD process, and the boundary of stable interface and unstable interface was divided. The study showed that the balance effect of gravity on the competition between capillary force and viscous force was the main reason for the stability of GAGD flooding leading edge. The stability of the oil-gas interface can be ensured by controlling the bond number to be greater than 2.75×10−4 and the capillary number to be less than 2.48×10−3. With a constant bond number, an increase in the capillary number leads to a gradual transition of the oil-gas interface from stable to unstable. Similarly, with a constant capillary number, an increase in the bond number causes the oil-gas interface to shift from stable to unstable. The fractal dimension divides the boundary between stable and non-stable displacement. When Df is greater than 1.87, the oil interface is stable, when Df is less than 1.75, the oil interface is viscous fingering, and when Df is between 1.75 and 1.87, the oil interface is mainly capillary fingering.
Mechanism recognition and application effect analysis of air injection development in ultra-low permeability oil reservoirs
Authors: Xin Liu
Published: November 2024

There are few application examples of air drive development technology in ultra-low permeability oil reservoirs in China. The article relies on the air drive development block of H oilfield, and based on the results of core start-up pressure gradient experiment, relative permeability experiment, gas composition experiment, and gas swelling experiment, conducts research and analysis on the seepage mechanism and low-temperature oxidation mechanism of air drive development, demonstrating the advantages of air drive development in oil displacement mechanism of ultra-low permeability oilfield. Based on the basic parameters of oil fields developed by air flooding both domestically and internationally, the specific blocks suitable for air flooding development in H oilfield are selected. The feasibility of conducting air flooding development in low permeability oil fields is demonstrated from three aspects: indoor real core experimental data, safety, and the maturity of existing equipment and technology. At the same time, an analysis is conducted on the development status of the air drive block in H oilfield. By comparing the development effects with adjacent water injection blocks, it is demonstrated that the air drive development effect in ultra-low permeability oilfield is superior to water injection development.
Study on the Multiphase Flow Behavior in the Jet Pump Lifted Natural Gas Hydrate Wells with Combined Depressurization and Heat Injection Method
Authors: Ping Xiaolin , Han Guoqing , Zhang Jiqun , Wang Hongliang , Liu Changchun , Liu Jungang
Published: November 2024

Natural gas hydrate production tests have been carried out successfully with different exploitation methods and gas recovery drainage technologies. The purpose of this study is to elucidate the fluid flow behavior in the jet pump lifted natural gas hydrate wells and optimize hot water injection parameters for the jet pump drainage gas recovery technology. The mechanism of jet pump drainage recovery of natural gas hydrate wells was analyzed and its applicability to natural gas hydrate exploitation with combined depressurization and heat injection method was demonstrated. In addition, multiphase flow models of tubing and annulus were established respectively for the phenomenon of countercurrent flow of heat exchange in the jet pump drainage gas recovery process, and the corresponding multiphase flow laws were derived. Based on the study of multiphase flow, sensitivity analysis and optimization of heat injection parameters were performed. It has been demonstrated that jet pump drainage gas recovery technology is suitable for the exploitation of onshore natural gas hydrate with combined depressurization and heat injection method. The multihphase flow behavior in the tubing and annulus of the jet pump lifted natural gas hydrate wells was disclosed in this study. Numerical simulation results show that the temperature and pressure distribution in the wellbore of the jet pump lifted natural gas hydrate wells during the recovery process are affected by the injection conditions. This study provides theoretical guidance for the production optimization and hydrate prevention and control in the wellbore of the jet pump lifted natural gas hydrate wells.
Design and Optimization of Direct-Drive Drilling Permanent Magnet Synchronous Motor
Authors: Mei Lianpeng , Xiao Wensheng , Cui Junguo , Zhang Qingxue , Yu Xiaolong
Published: November 2024

A direct-drive drilling electric drilling tool is developed due to the problems of long transmission link, low efficiency, and high failure rate of traditional electric drilling tools. In this paper, the key components of the direct-drive drilling permanent magnet synchronous motor (DPMSM) are designed and calculated, and the robust parameters optimization is performed by Taguchi method with efficiency and cogging torque as the optimization objectives. The air-gap length, thickness of permanent magnets, pole-arc coefficient, and width of slot top are selected as significant factors, and the impact of the optimized parameters on the efficiency and cogging torque of the DPMSM is calculated with orthogonal experiment to obtain the optimal combination of factors. Comparing the DPMSM’s performance before and after optimization, the cogging torque is reduced by 80.1% and the efficiency is improved by 0.24% after optimization. Finite element simulation of the electromagnetic characteristics of the optimized DPMSM under no-load and load conditions is carried out to verify the rationality of the optimization. Calculate the main losses of the DPMSM and the heat generation rate of key components. The analysis model of the DPMSM’s temperature field is established, and the temperature field simulation is carried out with and without drilling fluid respectively to further verify the rationality of the motor’s design. This work can promote the engineering application of downhole direct-drive electric drilling tools and provide technical support for the innovation of drilling equipments for marine energy.
Study on pretreatment technology of Oilfield Industrial Sewage
Authors: Zhang Yidong
Published: November 2024

At present, Oilfield industrial sewage treatment has not yet formed mature technology. However, with the development of tight oil blocks and the construction of large-scale fracture network fracturing, the industrial sewage generated in A oilfield (including fracturing flow-back fluid, substitution fluid, water for well-flushing, pressure relief water, etc.) has increased year by year. The quality of produced water in oilfield has gradually deteriorated. Oilfield wastewater treatment is becoming more and more difficult. The built oil-bearing wastewater treatment process has shown inadaptability. In recent years, by analyzing the process operation parameters, studying the characteristics of oily wastewater treatment process, and combining with years of practical management experience, A oilfield has optimized the industrial wastewater pretreatment process. Optimize the process flow according to the actual development and production. This study ensures the development effect of the oilfield. It lays the foundation for further reducing the investment and operation cost of sewage station renovation. At the same time, it is great significance to study and optimize the pretreatment process of industrial sewage in oil field.
Application of Microseismic Monitoring in Fracturing Process Evaluation
Authors: Huang Qijun , Guo Delong , Sui Guojie , Xiao Qian , Liu Youming , He Ping
Published: November 2024

Fracture-mesh control technologies, such as modified liquid system (controlled fracture technology), pulse fracturing reform and directional perforation technology, have been adopted in the large-scale fracturing process of well Qaiping 1 in Qaidam Basin. However, whether the technology has achieved the predetermined goal needs to be verified. In order to fully grasp the fracture morphology in each stage of fracturing construction, the underground microseismic fracture monitoring technology is used to reveal the fracture length, height, width, orientation and spatial distribution characteristics. Based on the analysis of monitoring results, the following conclusions are obtained. (1) The collection of microseismic event data plays a key role in interpreting the properties of fractures, so as to more accurately understand and predict the formation and development of fractures. (2) Real-time microseismic monitoring reveals the application value of a variety of special processes in the formation reconstruction effect, and the transformation of liquid system (controlled fracture process), pulse fracturing and directional perforating process have significant effects on fracture morphology.
Study on Temporary Plugging Agents and Process Simulation for Offshore Low-permeability Reservoirs Fracturing
Authors: Wang Yubin , Mu Huan , Liu Jian , Sun Baojiang , Deng Junyu , Hao Zhiwei
Published: November 2024

Temporary plugging fracturing technology is an effective method for extending the range of segmented fracturing in horizontal wells and improving the utilization between fractures in low-permeability reservoirs. In this study, a controllable degradable temporary plugging agent was synthesized by graft copolymerization of PGA and PLA with a material ratio of 3:1, under the catalysis of stannous octoate at 150°C. This approach allows for controlled degradation of the temporary plugging materials by protecting PLA, which has good affinity to water, and adjusting the molecular weight of the product. It reduces the initial degradation rate while increasing the later degradation rate. To consider the heterogeneity of natural fractures and reservoir physical permeability in shallow sea reservoirs, a numerical model for temporary plugging and fracturing of horizontal wells was developed. The model investigates the influence of parameters such as displacement and cluster spacing on crack propagation, resulting in the formation of a simulation method suitable for temporary plugging fracturing of horizontal wells in heterogeneous reservoirs. The research findings indicate that crack length and width gradually increase with the increase of displacement. The maximum crack spread area is achieved at a displacement of 5~8m3/min. Temporary plugging can be implemented when the cluster spacing is ≤12m, allowing for the full expansion of cracks that have not effectively expanded. The largest crack spread area is observed at a crack spacing of 5~8m.
Experimental Study on the Treatment of Produced Water from Carbon Dioxide Drive by Aeration Method
Authors: Wang Ying
Published: November 2024

To further explore the effective development of produced water treatment technologies suitable for low to ultra-low permeability oil fields, and to clarify the water quality characteristics of produced water from CO2 flooding. A study was conducted on the basic water quality characteristics of produced water from low to ultra-low permeability oil fields. Indoor CO2 gas removal experiments were conducted using the aeration method under 40°C atmospheric pressure conditions. The research results indicate that the CO2 content in the extracted water is one of the important influencing factors for the changes in characteristic parameters such as water pH, mineralization, and corrosion rate; Under the condition of 40°C atmospheric pressure test, the aeration method has a significant treatment effect on the produced water from CO2 flooding, which can effectively remove 70% of the CO2 in the water, thereby improving the pH of the water to 8, and effectively inhibiting the corrosion rate of the produced water below 0.076mm/a.
Feasibility Theory and Practice of CO2-EOR in High CO2-Content Near-saturated Edge-bottom Water Reservoir
Authors: Sun Jiangfei , Liu Tongjing , Zhang Yanan , Li Yuntao
Published: November 2024

CO2-EOR technology for low-permeability tight oil and gas reservoir is in the ascendant, and CO2-EOR technology for old oilfields has not been paid enough attention, but the implementation scale has great potential, and the expected effect and implementation conditions are good. The feasibility of CO2-EOR technology in the ultra-high water cut stage of high CO2 content, near saturation pressure and edge-bottom water reservoir was studied theoretically, and the field implementation effect was tracked and evaluated. Via petrophysics, reservoir engineering, and site case analysis, a relatively comprehensive reservoir numerical model was developed, clarifying the impact of periodic gas injection volume, gas injection rate, soak time and liquid production rate on the production effect of CO2 huff and puff were clarified. The key injection-production parameters of CO2 huff and puff test wells were designed, and the feasibility study progress of CO2-EOR in near-saturated edge-bottom water reservoirs with high CO2 content was summarized. The theoretical research shows that the change rules of gas-water dual-drive, CO2 water control and oil increase in the process of CO2 huff and puff in high CO2 near-saturated edge and bottom water reservoirs, and reveals the synergistic mechanism of CO2 huff and puff to suppress water and increase energy. The tracking evaluation shows that the sweep condition of CO2 after huff and puff in the test well is complex, the storage ratio is in the range of 40%-70%, the stage oil increase is in the range of 700t-3000t, and the optimized oil increase and oil change rate can reach 2.7t/t. Based on the comprehensive theory and practice, it is considered that CO2-EOR has good potential for high CO2 near-saturated edge and bottom water reservoirs under fine control. This study has guiding and reference significance for CO2-EOR technology and application in similar oilfields at home and abroad.
Experimental Evaluation of Energy Enhancement and Fracturing Fluid Flowback Effect for CO2 Pre-Fracturing in Shale Reservoirs
Authors: Lv Yuanjia , Luo Mingliang , Zhang Mian , Wang Kai , Zhan Yongping , Zhang Shuanghuan , Zhao Chunguang
Published: November 2024

Liquid CO2 pre-fracturing is a promising reservoir stimulation technology due to its advantages of increasing reservoir energy, low reservoir damage, and high fracturing fluid flowback rate. The on-site flowback scheme currently relies mainly on experience and requires further optimization of the energy enhancement effect and the flowback system. This paper presented a study on the changing law of liquid CO2 pre-fracturing energy-enhancing effect and fracturing fluid flowback rate in shale reservoirs was carried out by applying the experiments of drive-off and pressure-reducing flowback. The results indicate that, the injection of CO2 followed by linear gel fracturing fluid increased the energy (pressure) of the core system by approximately 322.8% compared to the injection mode of CO2 fracturing alone, and increased the energy (pressure) of the core system by approximately 24.1% compared to the injection mode of linear gel fracturing fluid. The energizing effect of the core system showed a trend of increasing and then decreasing with the increase of CO2 injection, and the best effect was achieved when the injection ratio of linear gel fracturing fluid to CO2 was 1:1. The flowback rate of the fracturing fluid and oil recovery both increased as the flowback differential pressure increased. Extending the soak time can increase the oil recovery, but the increase gradually decreases with the extension of the soak time. Additionally, the increase in soak time can improve the flowback rate of the core with relatively high permeability, but it has little effect on the flowback rate of the core with very low permeability.
Exploration and Practice of Synergistic and Efficient Development Technology for Gas-Capped Condensate Gas Reservoirs and Oil Rings
Authors: Zhang Youyin , Yi Chuanjun , Hu Zongfang , Zheng Qiang , Wang Miaomiao , Ye Yong
Published: November 2024

The oil-ringed condensate gas reservoir is one of the more unique and complex types of oil and gas reservoirs. The stable oil and gas interface is crucial for the efficient development of such reservoirs, and the fundamental means of addressing the issue lies in maintaining the dynamic balance between the gas cap and the oil ring. In this paper, we address issues such as the rapid decline in oil ring production, gas cap breakthrough, and increased condensate oil loss exposed during the development of the R carbonate reservoir in the Caspian Sea Basin of Kazakhstan. Using reservoir engineering and numerical simulation methods, we optimized synergistic development ideas and the boundaries of exploitation policies for gas-capped condensate gas reservoirs and oil rings. We formulated reasonable development parameters such as extraction rate, injection-production ratio, barrier water injection ratio, and proposed dynamic control standards for zoning and classification. After implementing the plan, the gas-oil ratio of the oil ring significantly decreased, with a reduction rate of 12 percentage points. The gas production per unit pressure drop increased by 40%. The annual decline rate of condensate oil decreased from 23.6% to 13.8%. All development indicators exhibited characteristics of benign development, providing a theoretical foundation and technical methods for guiding the efficient development of similar oil and gas reservoirs.
Research on Ultrasonic Guided Wave Pipeline Defect Detection Method Based on Modal Analysis
Authors: Liu Wencai , Cai Weijiang , Kang Le , Fang Yufeng
Published: November 2024

Pipelines are important transmission media in the petroleum industry, and their safe and stable operation is of great significance to industrial safety. The secure and reliable operation of oil and gas pipelines holds paramount importance for industrial safety. The significance of non-destructive testing (NDT) technology in this context is steadily growing. Presently, guided wave-based pipeline defect detection technology has garnered considerable attention. This method is noteworthy for its extensive coverage, ability to inspect the entire cross-section, and its capability to conduct inspections without disrupting ongoing production processes. Research focused on the displacement distribution of various modes of guided waves, exploring different excitation methods for each mode. The investigation also delved into the interaction mechanism between guided waves and pipeline defects; Conducted research on the detection of axial, circumferential and radial dimensions of defects using different modes of guided waves, and carried out experimental verification, studying the transformation law of the reflection coefficient of the defect reflection echo when the flaw size changes provide a reference for pipeline defect detection based on guided waves.
Pipeline defect detection system based on phased array excitation technology
Authors: Gong Yanshuang , Liu Wencai , Liu Nan , Tan Chuanjiang , Tong Gen
Published: November 2024

To address the challenges of non-destructive testing of professional industrial pipeline conditions, this paper designs a pipeline defect detection system based on phased array excitation technology. Online/offline detection equipment can be selected according to different application scenarios, achieving various functions such as phase delay calculation, ultrasonic data collection, and graphical display of calculation results. This article mainly elaborates on the principle of phased array excitation technology, the circuit design of detection equipment, and the overall design of upper computer software, proposing a practical solution for non-destructive testing of industrial pipelines.
Research and Practice of Sand Control Completion Technology Optimization in Western H Oilfield
Authors: Song Rulin , Zhu Yingbin , Yan Guofeng , Peng Libin , Peng Yuankui , Pu Shijie , Song Yangrong , Li Fan
Published: November 2024

In view of the problems of poor reservoir physical properties, high clay content, loose cementation, shallow burial, low compaction degree, low temperature in the middle and deep oil layers during the development process of unconsolidated sandstone reservoirs in the western H oilfield, the original sand control technology has poor adaptability and short sand control validity period., this paper carried out research on the optimization of sand control completion technology. In the study, a series of optimization studies were conducted, including analysis of acoustic time difference in sand producing layers, simulation of sand control formation compaction, optimization of gravel filling particle size, and sand control tools. A high-strength artificial wellbore and cyclic gravel filling sand control completion process suitable for different sand producing well conditions were developed and applied in practice. The research results and on-site practice indicate that the high-strength artificial wellbore sand control completion technology has good adaptability in low-temperature and long wellbore sand production wells; The cyclic gravel filling sand control completion technology has the advantages of simple construction, low cost, and low probability of major repairs in conventional shallow sand producing wells; The complementary advantages of the two processes effectively solve the problem of sand damage in H oilfield. Since 2021, the optimized sand control completion technology has been applied 46 times in H oilfield, with an average recovery oil production of 3.4t per well and an average effective period of over 500 days for sand control. The overall input-output ratio is 1:2.8, achieving good benefits and having high promotion and application value.
Research and Tests on the Technology of Releasing and Fishing Stuck Throttles Under Pressure
Authors: Wang Sifan
Published: November 2024

In order to solve the problem of gas well shutdown caused by fishing failure due to stuck throttles, and to avoid situations such as the inability to lift the pipe string and high cost of handling stuck throttles, the basic structures of the slip-type throttles were analyzed. And based on the actual situation on site, it was determined that the deformation of the slip mechanism was the main cause of the throttles getting stuck. And combined with conventional bridge plug drilling and grinding, coiled tubing fishing, and steel wire fishing techniques, the technology of grinding and milling under pressure to release and fishing stuck throttles was studied. Theoretical analysis has been conducted on the feasibility of using coiled tubing mill to break the slip mechanism of the stuck throttles, including mill torque, construction displacement, drilling pressure, etc. At the same time, the technical principle and operation process of gas lift fishing throttles were introduced. Two three-packer string wells were successfully tested in the field. After the stuck throttles were milled and unblocked by the coiled tubing, the stuck throttles of Φ73.0 mm tubing were successfully salvaged, one of which was fished by gas lift. The average construction time is less than 2.5 days. The research results show that the technology of grinding and milling with pressure to release and fishing stuck throttles is safe and efficient, providing a new technical means for dealing with stuck throttles and has good promotion and application value.
Research on Factors Influencing the Production of Deep Shale Gas Wells in Weiyuan Block : A Case Study of X Well on Platform A
Authors: Liu Ji , Li Changmian , Wang Tao , Song Lixin , Lv Shiquan , Zhang Tingshuai
Published: November 2024

The practice of Weiyuan deep shale gas development shows that there are many factors that affect the gas production, resulting in significant differences in gas production between wells in the same region and on the same platform. In response to the phenomenon of low gas production, low wellhead pressure, and high flowback rate in Well X on Platform A, using data from drilling, fracturing, and gas production profile testing, this study examines the impact of geological and engineering factors on gas well production through gray correlation analysis and geological engineering integrated numerical simulation methods. The results show that: ① The production of adjacent wells reduces the formation energy, resulting in a large pressure drop rate after the pump is stopped in the corresponding fracturing section of the well, poor fracturing effect and low gas production contribution; ② The order of the influence of geological factors on the gas production rate of each section is: gas content > Si content > Al content > GR value> Ca content;③The segment with natural fractures and faults contributes significantly to gas production, but its long-term effectiveness needs further evaluation. This study will provide useful references for target location optimization, fracturing design optimization, and overall development deployment of deep shale gas horizontal wells in Weiyuan.
Study on the Shear Degradation Law of Polymer Drag Reducing Agents
Authors: Lv Shiyi , Li Chuanxian , Li Xinyuan , Lu Wang , Zhang Wu , Yao Bo , Sun Guangyu , Yang Fei
Published: November 2024

The use of drag reducing agents in oil pipeline transportation can reduce driving energy consumption and has certain energy-saving benefits. However, irreversible degradation occurs when polymer drag reducing agents are sheared through pumping. In order to study the viscosity loss of polymer drag reducing agents caused by mechanical shear during the pumping process, the combination of methods such as a rotational rheometer and an indoor drag reducing loop testing system was used to test and analyze the rheological and drag reducing properties of the drag reducing agent solution, and to study the shear degradation law of polymer drag reducing agent solution under different conditions. The results showed that the shear stress of the polymer drag reducing agent solution increased with the increase in shear rate, and the viscosity increased with the increase of shear stress, showing shear thickening. When the polymer drag reducing agent solution is not sheared, the drag reduction rate increases and then decreases with the increase of concentration, and reaches the maximum value at 20 mg·L−1. However, after shear, the drag reduction performance decreases rapidly, but the high concentration still maintains a good drag reduction rate. The research results provide a theoretical basis for improving the performance of polymer drag reducing agents under different operating conditions and play a guiding role in further improving and perfecting the polymer drag reducing technology.
Study on Mechanism and Effect of Different Viscosity Reducing Methods on Offshore Heavy Oil
Authors: Liao Hui , Liu Zongbin , Liu Dong , Ge Taotao , Du Chunxiao
Published: November 2024

Bohai is rich in heavy oil. And its efficient development is significant. In this essay, ordinary heavy oil and extra one were selected, and the viscosity characteristics was also investigated referring to its internal composition. And so as the reducing viscosity effects of steam, oil-soluble viscosity reducer, diesel, emulsifier, flue gas and carbon dioxide. The experimental results show that resin and asphaltene content have positive effect on the viscosity of heavy oil. Compared with ordinary heavy oil, the drop is significantly greater when the temperature increases by 10°C. For ordinary heavy oil, the inflection point temperature is from 50°C to 70°C, and for extra-heavy oil, it is above 100°C. For ordinary heavy oil, its flow effect can be better improved without too high temperature, while it’s totally different for super heavy oil. For which, higher temperature and other auxiliary viscosity reduction methods are needed to achieve better flow performance. Diesel oil reduce viscosity of heavy oil by similar solubility principle, but the demand for diesel oil is large. At 50°C, the viscosity of super heavy oil with 0.5% emulsion viscosity reducer added is 36 mPa·s, but the water content needs to reach above 30%.Oil-soluble viscosity reducer reduces viscosity by dissolving asphaltenes and resins and dismantling aggregate structure of heavy oil aromatic flakes.However, the dosage should reach about 20 %, so that the viscosity of super heavy oil can be reduced to the level of dilute oil. Overall, for developing super heavy oil, steam compound with oil soluble viscosity reducer can be taken into account at the early production stage, and the emulsion viscosity reducer can be used in the middle development stage and wellbore viscosity reduction and lifting process. Finally, for ordinary heavy oil, flue gas’s viscosity reduction effects, nitrogen and carbon dioxide are investigated. It is found that the viscosity reduction effect of carbon dioxide is the best, followed by flue gas and nitrogen. Considering the offshore gas source, cost and carbon emission requirements, it is recommended to use flue gas in the field. The research provides theoretical guidance and technical reference for development of different types of offshore heavy oil.
Experimental Study on Effects of Various Factors on Bottom-Water Reservoir Sweep Based on A Two-Dimensional Plate Physical Model
Authors: Zhang Zhang , Cai Hui , Quan Hong-hui , Tan Jie , Liu Chun-yan
Published: November 2024

Horizontal Wells have obvious technical advantages in developing bottom-water reservoirs. Scholars at home and abroad have conducted many physical simulation studies on the development mechanism of horizontal wells in bottom-water reservoirs. In this paper, physical simulation experiments of sweep coefficients with or without intercalation and different displacement velocities, different permeability, different fluid viscosity and different reservoir thickness are carried out. The water sweep of the horizontal well bottom under different conditions is analyzed. The experimental results show that the existence of intercalation can delay the water appearance time, increase the anhydrous oil recovery period, and increase the final recovery factor. Controlling the liquid production rate can alleviate the bottom water coning phenomenon, expand the sweep area and increase the ultimate recovery factor. When the reservoir permeability is too high, the flow resistance is small, the water appearance is early, the anhydrous oil production period is short, and the final recovery factor is low. When the reservoir oil viscosity is high, the water sweep area is small and the final recovery factor is low. As the thickness decreases, it becomes easier for water to break through and reach a smaller area, resulting in lower final oil production.
LSTM Recurrent Neural Network Based Method for Identification of PDC Drill Bit Operating Conditions and Its Application
Authors: Chen Chang-chang , Ji Guodong , Lv Zehao , Sun Yu-qi , Yu Jinping , Zhang Hong-yuan
Published: November 2024

PDC drill bit underground operating conditions identification is one of of the difficulties during the drilling operation. It is of great significant for the drilling improvement and accurate construction formation to accurately identify the complex operating conditions during drilling the operation such as PDC bit wearing and stick-slip vibration, etc. In this paper, data of relationship between torque, rate of penetration (ROP) signal and weight on bit (WOB), rev were obtained through lab simulation experiment, after which, a relationship database of torque, ROP signal and WOB, rev was established, a single-layer LSTM recurrent neural network (LSTM-RNN) was constructed, the number of neurons, batch size and optimizer type of LSTM layer were optimized. With BPTT algorithm, LSTM model was trained and tested on the training set containing 6000 groups of data, and achieved the goal of identifying the bit operation conditions against the input of WOB, torque, rev and ROP signal parameters. Based on this model, the PDC bit underground operating conditions identification software was compiled, and was connected to the logging unit to realize real-time identification of bit underground operating conditions, and field test application was successfully carried out in Mahu 1 Well Region. The research showed that the convergence speed was fast and the time cost was at the lowest when the number of neurons of LSTM model was 50, and that the optimized Adam optimizer model could meet the requirements of convergence speed and prediction accuracy with the lowest loss value. The classification accuracy of this model on the test set reached 94% and the accuracy of the prediction method was also verified by field test application. To sum up, the method of LSTM-RNN based PDC bit underground operating conditions real-time identification can better meet the requirements of accurate identification of PDC bit underground operating conditions in the practical drilling, and has guiding significance for the judgement of PDC bit operating conditions on site and formulation of scientific construction decisions.
Numerical Simulation of Gas-suspended Proppant Migration Based on Equivalent Principle
Authors: He Yuan , Yang Bin , Li Yue , Guo Yufan , Wei Hongyu , Yang Bo
Published: November 2024

The gas-suspended proppant is composed of conventional proppant particles and hydrophobic aerophilic coating. The surface coating changes the surface wettability of the proppant and increases the adhesion of the proppant surface to the gas, changing the traditional liquid-carried proppant into a gas-carried proppant. The sand carrying capacity of low concentration polymer fracturing fluid can be greatly improved by using air-suspended proppant carrying technology. At present, there is no numerical simulation method aiming at the migration law of gas-suspended proppant. Based on the principle of equivalent substitution, the density of gas and particles is set as the calculated equivalent density during simulation. Similarly, the diameter of gas-suspended proppant is set as the calculated equivalent diameter during simulation. Then computational fluid dynamics software was used to simulate the Euler-Euler method. It is found that Euler-Euler method can simulate the placement of gas-suspended proppant in fractures. Compared with conventional proppant, gas-suspended proppant is not easy to settle during migration, and the settling sand bed still has fluidity and can be re-suspended. When gas suspension proppant density increases, the proppant sedimentation trend increased. Increase the injection rate of proppant, and the shape of long and high sand dunes will become shorter and lower. As the sand rate increases, the height of the sand bank rapidly increases.
Study on Coalescence Characteristics and Mechanisms of Salt-laden Droplets Under Electric-magnetic Coupling Field
Authors: Li Mofan , Yang Donghai , Cai Liangyu , Miao Jiaxu , Liu Haotian , He Limin
Published: November 2024

Electric-magnetic coupling dehydration technology is a novel method that can significantly improve the efficiency of water-oil separation in water-in-oil (W/O) emulsions. However, the electric-magnetic coupling mechanisms and its influence on droplet coalescence have not been understood from a microscopic perspective, which has become a bottleneck restricting the progress of this technology. In this study, the high-speed microscopic experiment and molecular dynamics (MD) simulation were combined to study the kinetic properties of droplets coalescence under an electric-magnetic coupling field, and the potential mechanisms of electric-magnetic coupling field strengthening droplet coalescence were articulated from the perspective of salt ions migration and energy evolution. The results show that the experiment and simulation have excellent qualitative consistency. As water molecules polarise and migrate, the contact interface between adjacent droplets forms a cone tip during the approach process. The contact point of the droplet forms hydrogen bonds due to the mutual attraction of water molecules, which are then transformed into a continuously expanding liquid bridge. The salt ions in the droplet undergo migration deflection by the electric-magnetic coupling effect, which may affect the surface charge distribution of the droplets. During the process of droplet coalescence, strong electrostatic attraction occurs between molecules, leading to a significant increase in coulomb potential and dominating the overall potential energy variation. However, excessively small molecular spacing induces exchange repulsion, thereby reducing the van der Waals potential. The study results are of guiding significance for sounding droplet dynamics theory and guiding the research and development of electric-magnetic dehydration equipment.
Geological characteristics and volume fracturing adaptability of tight oil reservoirs in the Ordos Basin of China
Authors: Zhang Jinyuan , Chen Junbin , Lei Junjie , Xiong Jiao , Nie Xiangrong , Li Ziyan
Published: November 2024

In recent years, China’s dependence on foreign crude oil has gradually increased. The Ordos Basin has abundant oil, gas, and coal resource. Tight oil and shale reservoirs have become very important replacement resources. This article studies the geological characteristics and volume fracturing adaptability of the Yanchang Formation tight oil reservoir in the central region of the Ordos Basin, and uses X-ray diffraction experiments to analyze the mineral composition of the reservoir; Utilizing high-pressure mercury intrusion technology to achieve precise quantitative characterization of multi-scale pore structures in reservoirs; Using the Analytic Hierarchy Process, establish a numerical judgment matrix and factor weights to study the adaptability of volume fracturing in the region. The results indicate that the volume fracturing adaptability of tight oil reservoirs in the Ordos Basin is good.
Discussion on the Automatic Design Method of Well Trajectory for Cluster Well Platform
Authors: Chen Kuan
Published: November 2024

Shale oil and gas and other unconventional oil and gas resources adopt the development mode of cluster well group to achieve economic benefit development. Cluster well groups have the characteristics of small spacing between wellheads and limited space, and generally adjust trajectory parameters by designing individual artificial Wells one by one to meet the needs of geological target hitting and anti-collision and circumnavigation. Trajectory design affects the whole body, and the change of trajectory of one well causes all Wells on the same platform to readjust design parameters, which seriously affects the design efficiency. Therefore, on the basis of summarizing the experience of manual trajectory design, combining classical path planning algorithm and global planning algorithm, an automatic trajectory design model is established. A* path optimization algorithm and ant colony algorithm are used to construct the routing strategy method and rule set, and adapt the efficient manual guidance strategy for different risk classifications to achieve efficient automatic routing. A cluster well trajectory automatic design and routing module has been developed. Automatic trajectory design tested 15 platforms, with an average time of 60s. The efficiency of trajectory design was greatly improved, and it has important guiding significance for the development of automated drilling technology.
Research and Application of Electromagnetic Heating Device for Digital Well Site Crude Oil Export
Authors: Li Zhaohui , Gao Baoyuan , Tan Huan , Xu Jun
Published: November 2024

Most well sites have discontinued using the associated gas-fired furnaces in response to the current situation in the oil fields. Coal-fired heating furnaces are environmentally polluting and prohibited due to local environmental regulations. These two heating methods can cause high costs, poor heating efficiency, and environmental pollution, which cannot be achieved through remote digital monitoring. Research has been conducted on the digital electromagnetic heating device for crude oil in the well site, focusing on introducing its main components and functions, including the electromagnetic heating body, frequency conversion control cabinet, and digital remote monitoring terminal. This device provides one-way internal heating without a heat source, resulting in high thermal efficiency, safety, environmental friendliness, and energy conservation. It comprehensively addresses the drawbacks of traditional electric heating, characterized by low efficiency, susceptibility to damage, and difficult maintenance. In 2022, it was applied at three well sites in the Tongzhai operation area of the Third Oil Production Plant of Changqing Oilfield, replacing the existing gas-fired and coal-fired heating furnaces to heat crude oil, as well as heating the heating belt and various electric heating pipes. This device is highly efficient, safe, environmentally friendly, and energy-saving. Additionally, the temperature and pressure of electromagnetic heating crude oil can be digitally and remotely monitored.
Research on oil well production analysis based on long-term slow-release tracer
Authors: Xu Gang , Wang Kongyang , Yan Qiehai , Li Jin , Zhao Kexian , Wang Xiaobo , Dong Changyin , Xue Dongyu
Published: November 2024

Downhole monitoring the production profile is crucial for the development of oil and gas reservoirs. Currently, the commonly methods for monitoring the production profile include logging tools and using tracer monitoring. The tracer monitoring method is more popular in oil field operations due to its wide applicability, simple process, low cost, low risk, and long monitoring time. However, compared to traditional logging tool monitoring methods, tracer monitoring has drawbacks such as data lag, difficulty in downhole installation, and unstable long-term effects. Bohai Oilfield has developed a new type of solid tracer and solved the problem of downhole installation by improving the structure of the downhole screen tube. This tracer uses polymer material as the skeleton. After entering the designated position, the internal tracer can slowly diffuse into the solvent through the pores in the skeleton, achieving slow release and long-term monitoring of the production profile of the oil well. In 2023, this new type was first applied in the D6 well in Bohai Sea, and a half month stable production stage liquid production profile was obtained through sampling. The monitoring results showed that: (1) Solid slow-release tracer monitoring technology can continuously obtain production layer information in complex environments and can be used for short-term rapid water exploration and long-term water production monitoring, identifying water breakthrough time and main water breakthrough location, (2) The distance between water injection well and D6 production wells is small, and the water injection volume in the injection wells is large. The tracer monitoring results show that there is a certain degree of water flooding in all 6 sections of each test layer, (3) The first test layer is the main liquid production section, the first and sixth test layers are the main oil production sections, and the first and second test layers are the main water production sections. The research results can determine the oil and water production situation of each section of oil well, identify the water breakthrough time and water outlet position, and provide a basis for the next development adjustment.
Application of 3D Geological Modeling Technology for Single Sand Body in Block S
Authors: Gao Hui-ying , Li Jian-qi , Gao Ruan , Leng Xiao-yong , Zhang Mei , Fan Cai-xia
Published: November 2024

The P oil layer is generally in a medium to high water cut period, with scattered macroscopic residual oil distribution. The reserves are mainly distributed in the microfacies of river sand bodies, and the main layer is severely flooded with water, resulting in ineffective circulation in some areas. Therefore, it is necessary to tackle the modeling technology within the layer and describe the remaining oil within the layer to meet the needs of tapping the potential of remaining oil during the high water cut period. This article takes the establishment of a three-dimensional geological model of a single sand body within the S block layer as an example. Based on the establishment of a fine structural model, the “plane and vertical dual control” modeling method is used. The implementation method is: controlling the range of sedimentary facies maps → using the top surface of the sand body as the top depth of the river channel → controlling the vertical shape of the river channel through the facies controlled sandstone contour map, thereby achieving the vertical shape of the river channel through the facies controlled sandstone contour map, and establishing a three-dimensional sedimentary facies model of a single sand body. Optimize the method for characterizing interlayers, achieve modeling of single sand body interlayers, and perform random simulation interpolation in phases to obtain attribute models. The use of a single sand body model within a layer can visually display the three-dimensional channel morphology and classify the identified connected bodies within the study area. The upscaling method of sedimentary facies models with irregular boundaries greatly reduces the number of model grids and provides a relatively refined geological model for numerical simulation.
Research and Field Application on Extreme Subdivision Water Injection Technology for Low Permeability Reservoirs
Authors: Shao Zhiyong
Published: November 2024

Low permeability Block A is about to enter the development phase of extremely high water cut. Due to the low overall recovery degree and residual oil scattered sporadically, the efficient development meets more difficulty and conventional residual oil analysis and adjustment methods cannot fulfil the current needs of precise development. To enhance the reservoir utilization degree, we conduct extremely concise zonal water injection experiment from three aspects: sand body description, policies establishment, and proper technique application. In terms of sand body description, four types of sand-body distribution patterns were summarized through fine characterization of vertical, planar, and spatial single sand bodies, clarifying the origin and potential distribution of residual oil. In terms of development policy, numerical simulation and reservoir engineering methods have been comprehensively applied to determine the subdivision combination of injection layers and reasonable water allocation boundaries, and subdivision principles have been established, considering single septation to thin and thick layer with combining enhancing -controlling. In terms of supporting technology, we have studied the small space subdivision process of small compartments, optimized the testing and adjustment methods, and finally achieved accurate separation, strict clamping, and accurate matching of water injection layers. Through the research and practice, it realized the finest septation of the water injection to extremely enhance the subdivision degree and the efficiency of the injection. It also have strengthened the utilization of thin and poor layers and effectively controlled the decline.