我国富含有机质泥页岩发育特点与页岩气战略选区

Development characteristics of organic-rich shale and strategic selection of shale gas exploration area in China

我国页岩气勘探才刚刚起步,目前研究主要集中在页岩气成藏条件和有利区评价方面。页岩气有利区优选还处于富含有机质泥页岩优选阶段,优选出的主要是页岩气发育远景区。受复杂地质背景和多阶段演化过程的影响,我国含油气盆地类型多、盆地结构复杂,盆地的不同演化规律直接控制着富含有机质泥页岩的发育与分布。为此,依据形成环境将富含有机质泥页岩划分为海相厚层富含有机质泥页岩、海陆交互相及陆相煤系地层富含有机质泥页岩、湖相富含有机质泥页岩这3种类型,并分别探讨了其页岩气勘探开发前景。结论认为:①海相厚层富含有机质页岩是我国近期页岩气勘探的首选;②海陆交互相及陆相煤系地层富含有机质泥页岩单层厚度较薄,但与致密砂岩气和煤层气有共生条件,发展页岩气与致密砂岩气等多类型天然气资源多层合采技术具有十分现实的意义;③湖相富含有机质泥页岩成岩程度普遍不高,需要进一步优选岩石强度较大、具备裸眼完井条件的层位进行勘探开发。

Shale gas,as a new type of unconventional natural gas resources,its exploration and development have got great success in the U.S.A.,and fast progress in Canada,Australia and other countries.Shale gas exploration in China has just started and its study is still focused on shale gas reservoir conditions and favorable area evaluation.China's preferred shale gas favorable area is mainly related with organic-rich clay and shale,and the major optimization is a prospective area for shale gas.Complicated geological background and multi-stage evolution lead to many types of China's petroleum basins whose structures are complex.Different evolution history of each basin directly controls the development and distribution of organic-rich shale.By the different formation environment,organic-rich shale can be divided into marine thick layer organic-rich shale,continent-sea intercrossing organic-rich shale,coal-bearing strata organic-rich shale,and lacustrine organic-rich shale.Among them,the thick layer marine organic-rich shale is of first priority in China's near future shale gas exploration;continent-sea intercrossing organic-rich shale and coal-bearing strata organic-rich shale are thin in single-layer,but they have symbiotic conditions with tight sandstone gas and coal-bed gas,so the multi-layer co-mining technology of shale gas,tight sandstone gas and many other types of natural gas resources has great practical significance;the lacustrine organic-rich shale's diagenesis degree is generally low,and needs further optimization of a horizon with high-strength rock and the conditions of open hole completion for exploration and development.