港东开发区明化镇组储集层特征及其物性差异的机理探讨

Reservoir features and mechanism discussion for its physical properties differences about Minghuazhen Group in Gangdong developing area

港东开发区明化镇组发育曲流河沉积,其中NmⅠ、NmⅡ、NmⅢ储集层物性主要为高孔隙度、高渗透率,而NmⅣ中孔隙度、中渗透率储集层较其余层位偏多。为了探讨相同沉积背景下河道砂体物性差异的原因,在沉积微相研究的基础上,采用电镜扫描、铸体薄片、压汞实验以及X射线衍射等方法对DJ5井区取心井岩心进行了储集层特征研究。研究结果表明,储集层主要为细砂岩及粉砂岩类,孔隙类型主要为原生孔隙,喉道类型主要为孔隙缩小型喉道和缩颈喉道,部分为片状喉道;储集层物性的影响因素包括沉积环境和成岩作用,其中泥质和方解石含量高是导致NmⅣ储集层物性变差的根本原因,NmⅣ储集层具有形成高岭石的地质条件。

Minghuazhen Group in Gangdong developing area developed meandering river deposition,in which the reservoir physical properties in NmⅠ,NmⅡ,Nm Ⅲ are mainly with higher porosity and permeability,while Nm Ⅳ is mainly with medium porosity and permeability. In order to discuss the reasons of the physical property differences in channel sand body at the same sedimentary background and on the basis of sedimentary micro facies study,the authors carried out reservoir characteristic study for cores from core wells in DJ 5 well area by using methods such as electric mirror scanning,casting flake,intrusive mercury experiment and X ray diffraction. The studying result indicated that the reservoir is mainly of fine sandstone and silty sandstone type,the pore type is mainly of primary pore,the throat type is mainly of pore narrow and non-reducing,part of it is sheet shape throat. The influencing factors for the reservoir physical properties include the sedimentary environment and diagenism,among them shale and calcite content is the basic reason that caused the Nm Ⅳ reservoir physical properties changed worse,and Nm Ⅳ reservoir has the geologic conditions to form kaolinite.