涪陵页岩气田高产的构造因素分析及思考

An Analysis of Geological Structure Factor behind the High Productivity of Fuling Shale Gas Field and Some Thoughts

涪陵页岩气田开始投产是中国页岩气开局取得的巨大成绩,但其高产的机理还有待进一步分析,对某些规律的认识还有待深入。两年来该气田几乎所有试采井都获得高产稳产,其储量丰度值亦相当高,这与美国多数页岩气井和中国的致密(砂岩)气井的产量曲线有相当大的差异。气田所在的焦石坝箱状背斜处于构造形变较强的背景上,多种裂隙发育。勘探目的层五峰组-龙马溪组一段的层间滑动及伴生裂隙也很发育,这为压裂改造创造了优越条件。目前的试采高产稳产很可能仅是压裂后游离气的表现,还需继续进行多种方式更长期的试采,以求知产量曲线变化的全过程。涪陵页岩气田有明显的特殊性,且与常规油气中的构造裂隙油气藏有一定的相似性。显然,不可简单地以涪陵页岩气的情况做外推,去规划四川盆地及其外缘的页岩气近期的储产量增长。要更加重视在实践中认识中国各地区、各时代、不同类型富有机质页岩含气的特殊性,找到其富集规律,形成与之相匹配的工艺路线和技术设备体系。

The startup of the Fuling shale gas field is a major achievement made by China in shale gas development,but the reason for the high productivity of the field and related laws are yet to be studied.Over the past two years,almost all pilot wells in the field have been stably productive and the reserve abundance of the field is also very high,as opposed to the production curves of most shale gas wells of the United States and Chinese tight（sandstone） gas wells.The Jiaoshiba box-shaped anticline where the field is located is in a setting of strong tectonic deformation,with a variety of fracture developments.There are also well-developed interlayer-gliding structures and associated fractures in interval 1 of the Wufeng layer-Longmaxi lay-er,the target layer for exploration,which has provided excellent condition for fracturing.The current stable high output during pilot production is very likely to be a manifestation of presence of free gas after fractur-ing and longer-term pilot production in multiple ways is still necessary in order to understand the entire process of changes in the production curve.The Fuling shale gas field has obvious particularities and shares some characteristics with tectonic fracture reservoirs of conventional oil and gas.Obviously,it is not wise to extrapolate simply based on the circumstances of the Fuling shale gas field to predict the near-term shale gas reserve and production growth for Sichuan basin and its peripheral areas.One should pay more attention to understanding the particularities of shale gas deposits in different regions,times and organic matter-rich shale in practice,try to understand the laws of gas accumulation and develop technical routes and a technol-ogy and equipment system that is fit for the characteristics of these shale gas deposits.