提升川南地区深层页岩气储层压裂缝网改造效果的全生命周期对策

为了实现深层页岩气的规模高效开发,以四川盆地川南地区泸州—渝西区块上奥陶统五峰组—下志留统龙马溪组深层页岩气储层为研究对象,系统分析了涵盖井位部署、钻完井、排采生产阶段的页岩气井全生命周期中影响页岩气储层压裂缝网改造效果的地质和工程因素,进而提出了有针对性的技术对策及下一步的技术发展方向。研究结果表明:①应力状态和断裂体系是影响缝网扩展程度的首要因素,不等时靶体及其钻遇率是形成复杂缝网的先决条件,发育的天然弱面区带是诱导裂缝延伸的重要介质,优质页岩储层厚度是衡量资源纵向上能动性的地质依据;②液体携砂效率与密簇是提升水力裂缝复杂程度的工艺保障,精细分段射孔工艺是实现储层横向上充分动用的技术核心,一体化压裂方案设计是避免井下复杂情况产生、实现储层得到最大限度改造的创新流程,合理的焖井与排采制度是保证气井长期高位稳产的必要措施;③提升深层页岩气井压裂缝网改造效果的全生命周期对策的内涵包括确定适宜的储层纵横向动用模式以实现对优质储层的充分改造、有效识别断层与弱面以减少井下复杂情况的产生、优化簇间距和砂液体系以保证水力裂缝网络规模达到最大化、通过制订合理的生产制度以保证气井最大估算最终开采量(EUR)的获取;④开展长水平段气井精细压裂方案设计、持续优化砂液体系、簇间距与施工强度、研究多层立体压裂技术是深层页岩气储层缝网压裂技术下一步的发展方向。

Whole-life cycle countermeasures to improve the stimulation effect of network fracturing in deep shale gas reservoirs of the Southern Sichuan Basin

In order to realize scale efficient development of deep shale gas, this paper systematically analyzes the geological and engineering factors influencing the stimulation effect of network fracturing in shale reservoirs in the whole life cycle of shale gas well covering well location deployment, drilling & completion and production by taking the deep shale gas reservoir of Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in the Luzhou-Yuxi Block of the southern Sichuan Basin as the research object. Then, corresponding technological countermeasures and the next development direction were pointed out. And the following research results were obtained. First, stress state and fault system are the principal factors influencing the propagation degree of fracture networks, unequal-timing target and its drilling rate are the prerequisite to the formation of complex fracture networks, the developed natural weak plane zone is an important medium to induce fracture propagation, and the thickness of high-quality shale reservoir is the geological basis for evaluating vertical resource development capacity. Second, liquid carrying efficiency and close cluster spacing are the technological guarantee to improve the complexity of hydraulic fractures, finest aged perforation technology is the core technology to realize the lateral reservoir development sufficiently, integrated fracturing scheme design is an innovative process to avoid the occurrence of complex downhole situations and maximize reservoir stimulation effect, and reasonable well soaking and production system is the necessary measure to ensure a long-term stable production of gas wells at a high level. Third, the connotation of the whole-life cycle countermeasures to improve the stimulation effect of network fracturing for deep shale gas wells includes establishing a suitable vertical and lateral reservoir development pattern to stimulate the high-quality reservoirs sufficiently, effectively identifying faults and weak planes to reduce the occurrence of complex borehole situations, optimizing cluster spacing and sand fluid systems to maximize the scale of hydraulic fracture networks, and formulating a rational production system to reach the maximum estimated ultimate recovery (EUR) of gas wells. Fourth, the next development direction of network fracturing technology for deep shale gas reservoirs include carrying out fine fracturing scheme design of gas wells with long horizontal sections, continuously optimizing sand fluid systems, cluster spacing and construction intensity, and researching multilayer tridimensional fracturing technology.