廊固凹陷马家沟组潜山白云岩储层特征及成因

Characteristics and genesis of buried-hill dolomite reservoir in Majiagou Formation, Langgu Depression

薛辉

XUE Hui

中国石油华北油田分公司勘探开发研究院，河北 任丘 062550

Research Institute of Exploration and Development, Huabei Oilfield Company, PetroChina, Renqiu 062550, China

利用岩心、薄片和地球化学等资料，分析了廊固凹陷马家沟组潜山白云岩储层特征及成因，识别出泥晶白云岩、砂屑白云岩、粉—细晶白云岩、中—粗晶白云岩等4种岩石类型，总体表现为低孔、低渗特征，局部发育中孔、高渗储层。研究区存在裂缝孔隙型和岩溶缝洞型2种储层类型，具有纵向分带、横向连续、区域层状分布和局部块状分布特征。进一步分析认为，该区存在4种白云岩化模式。准同生期白云岩化模式，是泥晶白云岩主要形成模式，形成于潮上带蒸发环境；回流渗透白云岩化模式，主要为粉—细晶他形白云岩形成模式，由富镁的高盐度卤水向下回流形成；混合水白云岩化模式，主要由大气淡水与海水混合形成，是粉—细晶自形白云岩和砂屑云岩的主要形成模式；埋藏白云岩化模式，为中—粗晶白云岩的主要形成模式，是在深埋条件下，受高温高压作用形成。

Based on the data of core, thin section and geochemical, characteristics and genesis of buried-hill dolomite reservoir in Majiagou Formation of Langgu Depression are studied. It is concluded that the research area developed four kinds of dolomite, dolomicrite, doloarenite, powder-fine crystal dolomite and medium-coarse crystalline dolostone. These reservoirs are generally characterized by low porosity and low permeability, and high-quality reservoirs developed in local area. There are two types of reservoirs. including fractured-vuggy and paleokarst fracture-cavern. The distribution of the reservoirs is characterized by vertical zonality, horizontal subregion, which exhibits bed-liked in regionality and block-liked in part. A further study shows that there are four kinds of genetic models of dolomite in research area, penecontemporaneous dolostone was dolomicrite and occured in evaporate environment in supralittoral zone; circumfluence dolostone was powder-fine crystal dolomite, which was formed by the procession of hypersaline brine downward penetration; mixing water dolostone resulted in the formation of powder-fine crystal euhedral dolomite and doloareniite, which developed in semi-closed to closed environment with meteoric water input. Burial dolomitization resulted in the medium-coarse crystalline dolostone, which was generated by high temperature and high temperature deep buried condition.

10.6056/dkyqt201805006