Dolomitization evolution and its effects on hydrocarbon reservoir formation from penecontemporaneous to deep burial environment  

作　　者：SHEN Anjiang LUO Xianying HU Anping QIAO Zhanfeng ZHANG Jie 

机构地区：[1]PetroChina Hangzhou Institute of Petroleum Geology,Hangzhou 310023,China [2]Key Laboratory of Carbonate Reservoirs,CNPC,Hangzhou 310023,China

出　　处：《Petroleum Exploration and Development》2022年第4期731-743,共13页石油勘探与开发（英文版）

基　　金：Supported by the China National Science and Technology Major Project(2016ZX05004-002);PetroChina Science and Technology Project(2019-5009-16).

摘　　要：Aiming at the scientific problem that only part of dolomite acts as dolomite reservoir,this paper takes the multiple dolomite-bearing formations in the Tarim and Ordos basins,NW China and Sichuan Basin,SW China as the study object,by means of mineral petrological analysis and geochemical methods including carbonate clumped isotope,U-Pb isotopic dating,etc.,to rebuild the dolomitization pathway and evaluate its effects on reservoir formation.On the basis of detailed rock thin section observation,five dolomitic structural components are identified,including original fabric-retained dolomite(microbial and/or micrite structure),buried metasomatic dolomite I(subhedral-euhedral fine,medium and coarse crystalline structure),buried metasomatic dolomite II(allotriomorphic-subhedral fine,medium and coarse crystalline structure),buried precipitation dolomite and coarse crystalline saddle dolomite.Among them,the first three exist in the form of rocks,the latter two occur as dolomite minerals filling in pores and fractures.The corresponding petrological and geochemical identification templates for them are established.Based on the identification of the five dolomitic structural components,six dolomitization pathways for three types of reservoirs(preserved dolomite,reworked dolomite and limestone buried dolomitization)are distinguished.The initial porosity of the original rock before dolomitization and the dolomitization pathway are the main factors controlling the development of dolomite reservoirs.The preserved dolomite and reworked dolomite types have the most favorable dolomitization pathway for reservoir formation,and are large scale and controlled by sedimentary facies in development and distribution,making them the first choices for oil and gas exploration in deep carbonate formations.

关 键 词：DOLOMITIZATION dolomitization pathway dolomite reservoir CARBONATES penecontemporaneous environment burial environment dolomite genesis identification template 

分 类 号：P618.13[天文地球—矿床学]