孤北地区二叠系煤成气储集层特征

孤北地区是济阳探区石炭-二叠系保存较为完整的地区。该地区石炭-二叠系具有良好的自生自储式煤成气成藏条件。二叠系储集岩类型主要为粗砂岩和含砾粗砂岩,碎屑矿物组份主要为石英。储集空间类型为原生粒间剩余孔、次生孔隙、晶间微孔、杂基微孔和裂缝等,其中以次生孔隙和裂缝为主。储集层类型属于低孔低渗型。二叠系各组中以上石盒子组孔渗条件为最好,山西组最差。沉积、成岩和构造作用是控制储集层优劣的三大因素,其中以构造作用为主控因素。将孤北地区二叠系储集层分为四类进行评价,结果表明,该区上、下石盒子组属于优质的Ⅰ类和Ⅱ类储集层,孤北古3井区为有利的储集中心地带。

Characteristics of Coal-Formed Gas Reservoir of Permian in Gubei Area

The Carboniferous-Permian in Gubei area is relatively less eroded away compared to other areas in Jiyang exploration area, which has favorable self-generating and self-reserving coal-formed conditions. The Permian reservoir rock is dominated by gritstone and pebbled gritstone with quarter minerals. The storage space of reservoir occurs in primary intergranular pore, secondary pore, intercrystal micro-pore and fracture, dominated by secondary pore and fracture, belonging to low-porosity and low-permeability reservoir. The Upper Shihezi formation is of the best reservoir quality, while the Shanxi formation is of the poorest one of the Permian. And sedimentation, diagenesis and tectonization are the three factors controlling the reservoir quality, of which tectonization is the main controlling factor. The Permian reservoir in Gubei area is divided into four types for evaluation. The results indicate that the Upper Shihezi and the Lower Shihezi reservoirs belong to high-quality ones of type I and type II, and Gu-3 Wellblock in Gubei area is a central area for petroleum reservoir.