鄂尔多斯盆地苏里格气田致密砂岩气藏稳产难点与对策

随着油气资源品位日趋变差,致密砂岩气藏已成为油气增储上产的主力之一,但对于如何确保已投入开发的(特)大型致密砂岩气藏长期稳产等问题,至今尚缺乏宏观分析的有效手段。为此,以我国陆上最大的致密砂岩气藏——鄂尔多斯盆地苏里格气田的最新研究成果为基础,以储量规模、开发规模、动态储量评价、气田产量递减规律、未动用资源评价5个方面为背景进行研究,分析了该气田稳产的难点,并从一个全新的角度为稳产难题的解决提供了重要证据和约束条件,进而对后期高效开发提供了技术支撑。结果表明:稳产的难点主要集中在井网不完善导致储量动用程度低、储层和流体特征存在差异造成产量递减不均、气水关系复杂让部分储量暂时难以有效动用、不同开采方式开采效果存在差异等7个方面。最后遵从"空间避开、时间错开、依靠技术、措施增产"的思路,运用水平井整体开发技术、混合开发井网综合优化技术、多维矩阵式气井管理技术和"主动性"排水采气技术等13项关键技术,进一步延长了该气田的稳产时间、提高了采收率。

Challenges to and countermeasures for the production stabilization of tight sandstone gas reservoirs of the Sulige Gasfield,Ordos Basin

With the grade of hydrocarbon resources becoming poorer, tight sandstone gas reservoirs may serve as the key to the enhancement of both reserves and productivity. Accordingly, high efficient and sustainable development of the existing large and overlarge tight sandstone reservoirs is very important. However, currently, there is no effective method available for macro-analysis. With the latest research findings from the Sulige Gasfield, the largest onshore tight sandstone gas reservoir in China, as the foundation, studies were conducted in five aspects, i.e. reservoir scale, development scale, dynamic reserve assessment, rules in production declines of gasfields and undeveloped resource assessment, to identify challenges to the production stabilization of gas reservoirs. In addition, key evidences and constrains for the solutions to the difficulties in production stabilization were proposed to provide necessary technical supports for high-efficient development in later stages. Research results show that the major challenges in production stabilization include seven aspects, such as low development induced by improper allocation of well patterns, uneven declines in productivity induced by specific features of reservoir formations and fluids, difficulties in the development of some reserves due to complex gas/water correlation, and differences in production performances by using different production techniques. Finally, guided by the development principles of "promoting productivity by using innovative technologies in different spaces and time", 13 key technologies, such as comprehensive optimization of development well patterns, multi-dimensional matrix for gas well management and "positive" water discharging and gas production technologies, were proposed to further prolong peak production time and enhance the recovery rates of tight gas reservoirs.