Accurate regulation of fluid composition in the wellbore is a critical technical challenge to enhance oil recovery (Kherroubi et al., Application of autonomous inflow control valve (AICV) technology to enhance oil production and reduce unwanted water production: case studies. Paper presented at the SPE water lifecycle management conference and exhibition, 2024; Prakasa et al, A rapid, simple, portable tool to design and analyse the value of inflow control devices ICD and autonomous inflow control devices AICD. Paper presented at the SPE Norway subsurface conference, 2020; Shi et al., Pilot test of deep profile controlling and sweep improvement based on plugging agent location optimization in offshore oilfield. Paper presented at the offshore technology conference Asia, 2022). This study aims to address early water breakthrough and excessive water-cut issues in oil production by developing a dual-control-mechanism-based autonomous inflow control device (AICD) for tri-phase flow regulation. The device integrates vortex dynamics and laminar pressure drop principles to achieve autonomous fluid identification and dynamic control. Structural parameters were optimized through computational fluid dynamics (CFD) simulations and validated via laboratory experiments. Results demonstrate that the device achieves a water-oil pressure differential ratio of 2.6–14 and dynamically adjusts control intensity based on flow rate variations. Four optimized structural configurations were proposed for crude oils with viscosities ranging from 5 to 800 mPa·s, ensuring effective suppression of gas/water influx during early production stages and rapid shutoff of high water-cut zones in later phases. The dual-control mechanism combines feedforward resistance adjustment (via viscosity-sensitive vortex-induced pressure drop) and feedback-driven channel closure (triggered by laminar flow pressure differentials), enabling full-lifecycle wellbore fluid management. Experimental data confirm its high sensitivity to water (flow resistance increases exponentially with water content) and adaptability to varying flow conditions. This innovation provides a robust solution for intelligent completion technology, significantly improving sweep efficiency and prolonging well lifespan.

[Purposes] This paper discusses the core competencies for young editors from scientific journals, which is expected to serve as a reference for the cultivation of young editors. [Methods] We analyzed the contest videos of the 48 finalists of the Fifth Editing Competition for Young Editors of Scientific Journals and developed the model for core competencies of young editors on the basis of grounded theory. Thereby, the ways for improving the competencies of young editors were proposed. [Findings] The core competencies of young editors are manifested as professional connotation, diversified skills, and keeping up with the times, which are respectively the basic, key, and influencing factors for the improvement of young editors. [Conclusions] Young editors should enhance occupational competence, develop diversified skills, and keep up with the times for better development.

Limited by the harsh downhole working environment and its structural feature, the sliding vane pump (SVP), which is an all-metal artificial lift method considered to be widely used in thermal recovery well and high gas/oil ratio well, has not been widely applied as expected. To further improve the efficiency of SVP, this study explores how to optimize the structure parameters and the usage of the pump based on its lifting characteristics, in view of the stagnation in the development of SVP. The main results show that (a) optimization of the inlet (outlet) position parameters will bring effective pre-expansion (precompression) of each chamber once it enters the closed state, to avoid ineffective suction and high-pressure backflow. (b) The mathematical model of the pressure difference between the two sides of the vane at any position is derived by means of piecewise function. (c) Increasing the number of vanes can not only increase the mean value of instantaneous displacement but also shorten the discharge period and reduce the flow pulsation. Compared with the adjacent even number of vanes, the odd number of vanes has a more uniform instantaneous displacement. (d) A larger cross-sectional area of the rotor groove can result in a lower volume efficiency at the same gas-liquid ratio, and the effect of rotor groove on volume efficiency is more significant under high gas-liquid ratio conditions.

Multistage fracturing technology is the primary means of reservoir stimulation in shale gas wells. However, the productivity contribution of each stage varies greatly. It is essential to evaluate the fracturing effect in order to make an optimized treatment design. In this study, we adopted an integrated workflow to assess the main control factors of geological and engineering parameters and a novel approach was proposed for post-fracturing evaluation. For this purpose, the H block in Zhaotong shale gas demonstration zone in Sichuan, China, has been taken as an object of study. The production predicting model was built based on the reservoir fracability index (RFI) which took both fluid type and proppant size differences into consideration. The results demonstrated that (1) if the reservoir quality index (RQI) in the target zone is greater than 5.0, then the area has good reservoir quality and development potential. (2) The RFI of H Block is generally at 4.0–6.0, it can be used as the key parameter to screen out the sweet spot. This method not only serves as a set of practical fracturing evaluation methods but also as a set of productivity prediction and fracturing optimization methods, which can provide strong support for the development of shale gas reservoirs.

An advanced numerical simulation method was developed to accurately characterize the heterogeneous geomechanical damage of heterogeneous matrix, hydraulic fractures, and natural fractures during production. The proposed model can automatically obtain the geomechanical damage correction coefficient according to the physical property differences of the reservoir, which reveals the heterogeneous geomechanical damage law of the spatial domain and the time domain so that the simulation results are more realistic. The heterogeneous geomechanical damage laws of multi-scale fractures are obtained. Due to the uneven pressure drop during the production process, each fracture is subjected to different geomechanical damage, and the permeability drops are not uniform. Particularly, we set the physical properties of each fracture differently in the model, which fully reflects the heterogeneity of the actual reservoir. Therefore, the geomechanical damage law of each fracture is different. The K/K0 distribution of each fracture can be seen in the simulation results. At the same time, the porosity and permeability are coupled based on the classification theory. Therefore, the whole model is dynamic. In unconventional reservoirs, the physical properties of the matrix are poor and the heterogeneous geomechanical damage has little effect on productivity. However, if natural fractures or hydraulic fracturing are developed, the heterogeneous geomechanical damage will have a significant impact on productivity, particularly during early production stages. If the natural fractures and hydraulic fractures are connected, productivity will be more affected. The novelty of the new numerical models that it can characterize the heterogeneity of heterogeneous matrix, natural fractures, and hydraulic fractures in both the time domain and the spatial domain.

目前在页岩油藏的多段压裂水平井压–闷–采过程中,缺乏系统完善的水平井压裂参数优化方法,为此,基于动态反演理论,建立了压裂参数优化方法.首先,根据页岩油藏压裂后形成的复杂缝网,采用数值理论和离散裂缝方法,建立了考虑页岩油储层特征和复杂天然裂缝的多段压裂水平井数值模型(EDFM-NM),得到了含离散天然裂缝的油藏压力解及多段压裂水平井的井底压力数值解;然后,应用动态分析方法,建立了包括段间距、闷井时间和井距的优化方法.应用建立的优化方法对长庆页岩油XC井进行实例分析,结果表明,实例井合理段间距为100～125 m,合理闷井时间为25～35 d,合理井距为590～610 m.研究结果为长庆油田页岩油藏压–闷–采参数优化提供了理论基础.

地热资源是一种低碳环保的可再生清洁能源,高效合理开发地热资源对于我国能源产业结构调整,推进实现"碳达峰"与"碳中和"目标具有重要意义.针对传统地热发电转化效率低、规模化开发难等问题,提出一种基于热电效应的地热资源发电技术,通过设计井下热电机装置,构建具有流体温度差的闭合回路,实现井下热电高效转化;建立井下热流温度场数学模型,定量预测井筒热量传递效率;创建地热发电经济评价指标,评估地热发电经济可行性.研究结果表明,井下地热发电技术能有效将热能转换为电能,适用于高含水的油气井;通过提高注入速率,串联安装多个热电机,可以有效提高发电量;地热发电技术单位电量费用为0.6元/(kW·h),随着规模化应用发电成本会进一步下降.研究结果为我国地热发电技术提供了一种低成本、大规模、高效开发的解决方案,为我国能源结构调整和节能降耗减排等研究提供借鉴.

现有微观孔隙结构研究手段多局限于在微尺度提供孔喉尺寸、孔喉比等孔隙结构参数,所得结果无法直接应用于岩心尺度及矿场尺度等宏观尺度的研究中,其研究结果与储层实际结合具有一定困难.为此,从多尺度评价角度出发,以碳酸盐岩岩心数据体为研究对象建立孔隙网络模型分析碳酸盐岩微观孔隙结构,在此基础上,根据分布函数及分形函数对其进行尺度升级,获得岩心尺度评价参数.结果表明:尺度升级后的岩心表现出明显低渗、致密特性,与孔隙网络模型分析结果相符.可见,对微观孔隙结构分析结果进行尺度升级具有一定可行性,并且升级结果对于宏观尺度的评价工作具有一定的理论意义.

Due to the mechanical structure and operating principle of sliding vane pump (SVP), an all-metal artificial lift equipment with high temperature resistance and high pump efficiency, an unbalanced radial hydraulic force always exists in it during oil recovery, which will cause damage on efficiency, safety and service life of production system. What's more, the flow behavior of fluid through the pump cannot be accurately characterized because current related works fails to capture the influence of the force mentioned. To bridge this knowledge gap, in this paper, the computational fluid dynamics method was introduced and used to analyze the radial hydraulic force under different operating parameters for the first time. On this basis, novel measures to reduce this unbalanced force were put forward, and a design scheme of concentric stator-rotor to completely eliminate the radial hydraulic force was proposed. Main results show that a) increase in eccentricity will contribute to the enhancement of discharge capacity, which will simultaneously aggravate the radial hydraulic force. And this force is proportional to the fluid viscosity, lifting pressure difference and rotation speed. b) The direction of radial hydraulic force of adjacent stages in multistage SVP is opposite. To reduce this unbalanced force, it is recommended to use even-numbered (odd-numbered) multistage pump when the number of total stages is small (large). c) The concentric design eliminates the radial hydraulic force at the expense of the function of self-regulating flow rate. Besides, the stator curve under concentric stator-rotor condition will degrade the kinetic characteristic of vanes.

在碳酸盐岩储层的酸化压裂改造过程中,酸液质量的优劣直接影响着最终的改造效果.目前,常用的酸液体系存在渗透性差、腐蚀高、缓速效果不佳等问题.通过室内实验,研选出了适宜的复合有机缓速酸主体酸液以及酸用降阻剂、缓蚀剂和铁离子稳定剂等助剂,开发出了一套适合碳酸盐岩储层的新型强渗透缓速酸液体系.实验室综合评价结果表明,该强渗透缓速酸液体系具有良好的缓速性能、较低的腐蚀速率以及更优的渗透性能.此项研究对碳酸盐岩油藏储量的充分动用及高效开发具有重要的理论指导意义和实际应用价值.

Water huff and puff in horizontal wells in tight reservoirs has achieved good results in replenishing formation energy. However, after multiple rounds of treatment, a rapid decrease in formation pressure takes place making it difficult to maintain stable production. To improve the oil recovery rate of tight reservoirs, it is imminent to change the development mode. In this work, the stress distribution characteristics at fracture tips were analyzed based on Irwin theory and elastic theory. A model of propagation and closure length of fractures was established based on the propagation mechanism of water injection-induced natural fracture and the energy balance principle of fracture mechanics. Surfactant imbibition experiments were carried out according to the imbibition principle of surfactant system, and the propagation law of natural fractures was described with numerical simulation to analyze the seepage characteristics of dynamic fracture network. On the basis of the above works, alternating water huff and puff into segmented injection and production was proposed according to the distribution law of dynamic fracture network. The developing process of an actual well case by these two developing modes was simulated to predict 18 years of cumulative recovery, pressure distribution, and recovery rate. Results showed that when stress intensity factor exceeds the fracture toughness, the natural fractures will extend along their original directions and get connected, forming an irregular fracture network. The lengths of fractures after propagation and closure will not bring about water channeling for they are far shorter than well and interval spacing. Surfactant could diminish the resistance of boundary layer by reducing the wetting contact angle, ending up with an improvement in imbibition efficiency. Radial displacement and dynamic imbibition occur simultaneously in a dynamic fracture network during the early stage of water injection, while static imbibition mainly occurs during injection shutdown period and well soaking. According to comparison, the swept area of segmented injection and production was larger, ending up with a continuous increase of simulated recovery rate and cumulative recovery. The findings of this study show alternating water huff and puff after to segmented injection and production in fractured tight reservoir can allow full play of dynamic fracture network’s potential and achieve effective enhancement in oil recovery rate.

深水油气井生产测试阶段采用复合泡沫材料技术能有效减缓环空热膨胀压力上升,保护管柱结构不受损坏,因此开展针对复合泡沫材料压缩性能的研究具有重要意义.根据Gibson模型中的多孔材料力学行为理论,对试制的复合泡沫材料进行压缩力学特征预测,在准静态单轴压缩试验和静水压压缩试验中,复合泡沫材料压缩过程中呈现出线弹性变形、屈服破坏和致密化压缩三个阶段的力学特征.分析了泡沫材料在不同配比、温度条件下的体积压缩率随静水压力的变化规律.结果表明:理论预测与试验结果基本一致,静水压力下的泡沫材料的启动压力要大于单轴压载屈服强度;环境温度对泡沫材料的体积压缩率影响不大,但会改变泡沫材料启动压力,随着温度的升高,启动压力会相应降低;不同微珠填充量对材料性能影响较大,随着空心玻璃微珠含量的增高,泡沫材料启动压力降低,体积压缩率增大.在案例井的现场应用中,证实了采用复合泡沫能有效控制环空热膨胀压力,保障管柱安全和井筒完整性.

This paper develops a mathematical model for rate transient analysis in multi-stage fractured horizontal wells with considering weak fluid supply. A new concept of additional skin factor is introduced in the proposed model to characterize the fluid supply. Then, the mathematical model are solved by using the perturbation transformation, point source integration method, Laplace transform, and numerical inversion, while the fracture flow equations are solved by fracture discretization and superposition principle. First, the flow regimes of multi-stage fractured horizontal wells with considering weak fluid supply are identified based on the rate transient behaviors, including wellbore storage and skin effect, bilinear flow, linear flow, pseudo-radial flow in the fractured zone, interface skin effect, pseudo-radial flow in the original zone, and boundary-dominated flow. The effect of additional interface skin makes the double logarithmic curve of production rate appear an abrupt "overlap". The results of the sensitivity study show that the abrupt "overlap" becomes more obvious with the increase of the fracture conductivity, fracture number, the stress sensitivity coefficient, especially the interface skin. Finally, the proposed mathematical model is used to perform a case study on the production data of actual tight-gas wells from the Ordos Basin. The interface skin factor, fracture half-length, fracture conductivity, and boundary radius are evaluated. Through the proposed model, the characteristics of weak fluid supply in tight gas reservoirs are fully understood.

滑溜水体积压裂是非常规致密储层的主要经济增产措施,支撑剂的运移与分布规律决定着复杂裂缝网络内支撑剂的最终分布形态和导流能力.文中采用PIV(粒子成像测速)系统捕捉支撑剂颗粒在主裂缝中的瞬时运移状态,研究了不同压裂液黏度、排量、砂比和支撑剂筛 目条件下支撑剂铺置后的砂堤平衡状态,揭示了砂堤前缘与末端流场的变化规律.结果表明:随着排量、砂比和支撑剂筛目的增大,以及压裂液黏度的降低,支撑剂颗粒在砂堤前缘入口处和离开砂堤峰部时的运移速度更快,湍流强度更大,形成的有效裂缝更长;砂堤处于平衡状态时的高度和时间随着排量增加而减小,砂堤整体形态变得平缓;砂比越大,砂堤峰部出现位置越靠近裂缝入口处;优化的排量为10～12m3/min、砂比控制在20％以下、压裂液黏度在6～16mPa·s、支撑剂筛目为40/70目时,形成的砂堤高度和长度最大.该研究成果可以为滑溜水体积压裂设计和施工提供有效的技术指导.

For constant rate production of a single well in a closed boundary fractured-vuggy carbonate reservoir, when the pressure wave propagates to the reservoir boundaries, boundary-dominated flow occurs, and the transient flow period ends, the reservoir will be in a state of pseudoequilibrium (i.e., pseudosteady state flow occurs, and the pressure at any point in the reservoir declines at the same constant rate over time). The characterization of fluid flow in the fractured-vuggy carbonate reservoir under pseudosteady state condition is of significance in describing the productivity index (PI) of the well. However, due to complex mechanisms (e.g., stress dependency of reservoir properties and crossflow between different systems of the reservoirs) during flow in fractured-vuggy carbonate reservoirs, researches on productivity prediction in fractured-vuggy carbonate reservoirs under pseudosteady state are very limited. The present work is aimed at developing a new analytical model for predicting flow in fractured-vuggy carbonate reservoirs under pseudosteady state condition. In the derived model, the crossflow between different systems (i.e., matrix, fracture, and vug) of the reservoirs was taken into account. In addition, based on Hooke’s law, a quantitative model was proposed to study stress-dependent permeability of the fracture system, which connects the reserve spaces. Moreover, the roughness morphology characteristics of fracture surface were taken into account with fractal theory. Finally, with our derived model, influences caused by various related factors on productivity were analyzed. The results show that well productivity during pseudosteady flow will be significantly affected by the morphology of fracture surface (e.g., fracture microstructure parameters) and effective stress. Specifically, due to effective stress, the fracture system in the fractured-vuggy reservoirs will be deformed, and the corresponding properties (e.g., permeability, porosity, and conductivity) will change, leading to the change of well productivity. In addition, there exists a negative relationship between the elastic storage capacity ratio of vugs and well productivity during pseudosteady flow. Moreover, a larger value of matrix-fracture interporosity flow coefficient or vug-fracture interporosity flow coefficient corresponds to a larger value of well productivity during the pseudosteady period. The new derived model is beneficial to improve the productivity prediction accuracy and reduce uncertainty. What is more, the findings of this study can help for providing theoretical reference for the design of efficient development of fractured-vuggy carbonate reservoirs.

碳酸盐岩储藏资源潜力巨大,是当前研究的热点和难点领域.为了准确评价缝洞型油藏产能特征,以三重介质流体渗流方程为基础,考虑应力敏感对储层渗透率的伤害,建立基质-孔隙-裂缝的三重介质试井分析模型.研究结果表明:无量纲压力及压力导数曲线随应力敏感性增强而整体向上抬升,随着时间的增加,上升幅度逐渐增大;将无量纲压力导数曲线的水平段取值作为特征值,当其值大于0.5时应考虑应力敏感的影响,反之亦反;"双下凹"形态可作为判断三重介质缝洞型油藏的曲线特征.对于强应力敏感性储层,应力敏感的影响不可忽视,渗透率应力敏感的准确表征有利于提高产能预测精度.

为了验证多层密闭环空热膨胀压力预测模型的准确性和适用性,更深入地探究油气井筒传热与环空压力之间的关系,有必要开展全尺寸环空压力模拟实验研究.通过设计符合油气井身结构特点和现场工况的双环空井段实验装置,模拟高温热流体在不同循环温度、循环流量和循环时间的条件下对密闭环空温度和压力造成的影响,分析实验中环空压力随温度增量的变化关系,验证理论模型结果的适用性.结果表明:双环空升温阶段,A环空比B环空升温增压速率更快,温度压力峰值更高;由于环空流体中含有部分无法消除的可压缩溶解气体,导致环空压力上涨幅比环空温度要小;提出环空压温比的概念来评估环空流体产生压力的能力大小,其中纯水受热膨胀产生的环空压温比最高,自然散热前期环空压温比更能反映流体产生热膨胀压力大小;实验测试数据与模型计算结果偏差均在10％以内,满足理论和现场实际需求.可见在实际计算中应该参考实验数据,考虑环空流体特性和气体压缩性质,提高预测精度.

微信公众号已逐渐成为学术期刊扩大传播范围、提高期刊影响力的重要新媒体之一."长江大学学报自然科学版"微信公众号起步较晚,关注度、推送量处于较低的水平.为充分发挥微信公众号的功能,促进学报的传播,通过整理微信公众号服务平台、利用清博大数据网站的数据,对微信公众号的运营情况进行了回顾和分析.针对微信公众号运营存在的困境,拟从推动开放科学、建立学报数据库、创建学报新媒体模式、组建数字化办刊队伍等方面开展微信公众号建设,形成"纸刊+网站+微信公众号"共行之势,助推期刊发展,提高学报传播能力.

In the oil and natural gas industry, artificial intelligence (AI) technology has penetrated into all links from exploration and development to construction sites. This paper investigates the application of artificial intelligence in each link of oil reservoir. It is found in investigation that each algorithm plays a different and important role at each stage and every link of oil accumulation development cannot leave the cooperation of artificial intelligence. But, the application of AI is mostly scattered, forming a physical isolation, a lot of single information-island. This situation increases the communication cost of cross-departmental data cooperation and the repetitive screening and recognition work has seriously affected work efficiency. To address unsolved problems with the current application of AI, AI-based geo-engineering integration in unconventional oil and gas are proposed this article considers. Integrate data islands, and realize internal resource sharing, treat exploration and development as an organic whole, extend exploration to development. This article takes the well factory operation mode, meanwhile, the real-time synchronization and coordination of all links has been fully realized. This kind of integration of geology and engineering is helpful to realize coordination and cooperation at all levels, regions, and disciplines, effectively benefiting development of unconventional oil and gas reservoirs.

酸化压裂是碳酸盐岩油气藏增产的主要措施和手段,即使采用较大规模施工,酸蚀缝长一般不超过120 m,而水力压裂技术能够实现大规模造长缝的目的.为此,开展水力压裂与酸携砂压裂相结合的复合酸化压裂技术研究及现场实验,以探索碳酸盐岩增产措施的新工艺技术.实验采用塔里木盆地奥陶系碳酸盐岩岩心,模拟高温高压地层条件,通过测试水力加砂压裂裂缝、酸化压裂酸蚀缝、酸携砂压裂裂缝、水力压裂与酸携砂复合酸压裂缝的短期导流能力,探索评价了碳酸盐岩地层增产改造的新工艺技术,实验结果表明了碳酸盐岩地层实施复合酸化压裂可以实现较好的导流能力.基于导流能力实验评价结果,优化设计了4口井的复合酸化压裂方案并进行现场施工,增产效果良好,为碳酸盐岩地层实施复合酸化压裂提供了有力的理论支持.