苏里格气田马家沟组膏模孔型储层特征及成因

含"膏模"孔泥粉晶云岩是鄂尔多斯盆地马家沟组上组合地层重要储集岩类型,其形成时间和成因对于该类型储层的认识具有重要意义.研究利用苏里格东区丰富的取芯资料,根据岩芯、薄片等观察手段,结合常规物性测试分析,综合研究含"膏模"孔型储层特征及其成因.结果表明,"膏模"孔主要发育于泥粉晶白云岩中,位于向上变浅序列中部,常可见未充...

Characteristics and Genesis of the Gypsum-mold Type Reservoir of the Majiagou Formation in the Sulige Gas Field

Gypsum-mold-bearing micrite dolomite is an important reservoir type in the upper Ordovician Majiagou Formation in the Ordos Basin, and its formation time and genesis are important for the understanding of this reservoir type. In this research, based on the abundant core data of the study area, using the analysis of conventional physical properties and observation methods such as core, thin sections, the characteristics of the reservoir containing "gypsum-mold" and its genesis are comprehensively studied. The results show that the "gypsum-mold" is mainly developed in the micrite dolomite, which is located in the middle part of the shallowing upward sequence, and the two types of non-semi-filled and fully-filled types are often seen. As a reservoir, that mainly develops three kinds of reservoir spaces:residual pores in gypsum mold and interbedded pores in bedrock. The physical property test shows that this reservoir has superior performance, whose average porosity is 5.34%, and the average permeability is 1.02 mD. The dolomitic seepage silt similar to the composition of the bedrock is filled in the "gypsum-molds". The vertical sedimentary sequence shows that the development of the "gypsum-mold" is controlled by sedimentary cycles, the top of the cycles is characteristic of exposure, and the karst system can be seen poured with mud from the next transgression, all indicating that the formation of the "gypsum-mold" is related to the eogenetic karst, that is, the pore is formed in the early diagenetic stage, not the epigenetic stage of traditional understanding.