二连盆地群低煤阶煤储层裂隙地质建模与精细描述

Geological modeling and fine description of fractures in low coal rank coal reservoirs of Erlian Basin Group

以二连盆地群霍林河盆地低煤阶煤储层为研究对象,通过在露天煤矿选取典型剖面进行实例解剖,辅以光学显微镜、CT扫描等室内测试分析的研究方法,精细描述研究区煤储层裂隙系统发育特征,构建目标煤储层垂向上空间裂隙发育模型,为后续工程开发提供参考。研究结果表明:霍林河盆地煤储层大裂隙系统及微裂隙均表现出良好定向性,外生节理倾角多近乎直立,内生裂隙及微裂隙多垂直于层面发育。显微裂隙主要为原生张性裂隙,未见具有构造特征的剪性裂隙。外生节理发育的程度与方向、内生裂隙形态特征受构造影响明显,但微裂隙发育程度主要受煤岩组分影响,受构造影响不明显。大裂隙系统少见充填,微裂隙充填度较大,在40%~50%,储层连通性整体较好。煤CT三维重建成像表明无机矿物充填空隙和未被充填空隙都具有分层分布特征,整体孔裂隙发育,Ⅳ煤组无机矿物充填较ⅢA煤少。

Taking the low coal rank coal reservoir of Huolinhe Basin in Erlian Basin Group as the research object,the typical section in the open pit coal mine is dissected by examples,supplemented by optical microscope,CT scanning and other laboratory test and analysis meth⁃ods to describe the coal in the study area in detail Reservoir fissure system development characteristics,build a vertical space fracture de⁃velopment model of the target coal reservoir,and provide reference for subsequent engineering development.The results of the study show that the coal reservoir large-fracture system and micro-fractures in the Huolinhe Basin show good orientation,the exogenous joint dip angle is almost upright,and the endogenous fissures and micro-fissures are mostly developed perpendicular to the plane.The micro-fissures are mainly primary tensile fissures,and there are no shear fissures with structural features.The extent and direction of the development of exog⁃enous joints and the morphological characteristics of endogenous fissures are obviously affected by the structure,but the degree of microfissure development is mainly affected by the composition of coal and rock,but not by the structure.Large-fractured systems are rarely filled,and micro-fractured filling is relatively large,about 40%to 50%,and overall reservoir connectivity is better.The CT three-dimen⁃sional reconstruction imaging of coal shows that the voids filled with inorganic minerals and unfilled voids have the characteristics of strati⁃fied distribution,and the overall pore cracks are developed.The inorganic minerals filled in theⅣcoal group are less than those in the II⁃IA coal.