川南深层页岩气开发实践与面临的挑战

Development practice and challenges of deep shale gas in southern Sichuan Basin

深层页岩气资源量丰富,开发潜力巨大,但工程地质条件相对略差,效益开发难度较大。为支撑深层页岩气的效益开发,以四川盆地南部地区威荣和永川气田的开发实践为例,针对深层页岩气构造复杂、断缝发育、优质储层薄、产量递减快、最终可采储量低等难点,以“布好井、打好井、管好井”为目标,在气藏精细描述、渗流实验等研究基础上,采用地球物理—地质建模—压裂模拟—数值模拟一体化方法,形成了以地质甜点评价与预测技术、复杂构造区井网优化设计技术、“四位一体”钻井跟踪保障技术和全生命周期生产精细管控技术为核心的开发关键技术体系。同时,根据开发中暴露出的问题,梳理总结了在“构造—断裂—应力场”耦合机理、小—微尺度裂缝精细刻画、开发技术政策优化等方面的难点,提出了持续攻关的方向。研究认为:①深层页岩孔隙度、含气量等地质参数与中深层基本相当,但工程参数更复杂,具有地应力高、水平应力差高和破裂压力高的特征,改造难度大;②深层页岩气已在甜点评价与预测、建模—数模一体化技术和精细生产管理等方面形成了关键配套技术,取得了较好的开发效果;③目前深层页岩气主要面临套变、压窜、最终可采储量不达标等方面的难题,需要持续深化地质精细评价、流体运移规律和建模—数模一体化等技术攻关。

There is great potential for developing deep shale gas resources,but the engineering geological conditions are relatively poorer,making it difficult for benefit development.In order to support the benefit development of deep shale gas,taking the development practices of Weirong and Yongchuan gas fields in the southern region of Sichuan Basin as an example,focusing on the difficulties of complex deep shale gas structures,developed fractures,thin high-quality reservoirs,rapid production decline,and low EUR,with the goal of“good well placement,good well drilling,and good well management”,a key development technology system is formed by use of the integrated method of geophysics,geological modeling,fracturing simulation,and numerical simulation based on the research on precise gas reservoir description and seepage experiments,which is characterized by geological sweet spot evaluation and prediction technology,well network optimization design technology in complex tectonic areas,“four in one”drilling tracking guarantee technology,and full life cycle production control technology.At the same time,based on the problems exposed during development process,the difficulties and challenges in the coupling mechanism of“structure-fault-stress field”,characterization of small-scale and microscale fractures,optimization of development technology strategies were summarized,and the problems that need to be continuously studied were proposed.The conclusion is that:①The geological parameters such as porosity and gas content of deep shale are basically equivalent to those of medium-deep strata,but the engineering parameters are more complex,characterized by high in-situ stress,high horizontal stress difference,and high fracture pressure,making it difficult to transform;②Key supporting technologies in dessert evaluation and prediction,modeling-numerical simulation integration technology,and fine production management has been formed in deep shale gas,with good development results;③At present,deep shale gas is mainly faced with challenges such as casing deformation,pressure channeling,and EUR non-compliance.It is necessary to further advance technical research in geological fine evaluation,fluid migration patterns,and modeling-numerical simulation integration.