白云岩埋藏溶蚀孔洞的形成机理与演化——来自高温高压溶蚀模拟的证据

Origin and evolution of burial dissolved vugs in dolomite:evidence from high-temperature and high-pressure dissolution kinetic simulation

白云岩是深层油气勘探的重点领域,溶蚀孔洞的发育程度是控制白云岩储层油气产量的重要因素之一。选取深层大量发育的晶粒白云岩,开展柱塞尺度和晶体尺度的高温高压溶蚀模拟实验,以探讨白云岩孔隙的形成和演化过程,明确孔喉结构控制因素和优质储层发育规律。取得了3方面成果认识:①白云岩经埋藏溶蚀趋于向孔洞型储层演变;②白云岩孔隙的类型和发育程度控制埋藏溶蚀速率;③埋藏溶蚀最初以优先溶蚀高钙白云石或方解石为特点。指出由于细中晶白云岩具有更好的先期孔隙发育条件,更易于接受强烈的埋藏溶蚀改造,具有更大的潜力成为规模优质储层,是深层油气勘探的重点。

Dolomite is the key field of deep oil and gas exploration,and dissolved vug plays an important role on the oil and gas production of dolomite reservoir.This paper aims to discuss the formation and evolution of dissolved vug and the development of high-quality reservoir based on the high-temperature and high-pressure dissolved kinetic simulation of plug-scale and crystal-scale crystalline dolomite considerably occurred in deep burial realm.Three aspects of result achieved include:(1)matrix pores in dolomite tend to transform into vug after the burial dissolution;(2)pore-throat types and abundance control the rate of burial dissolution;(3)burial dissolution starts with the dissolution of high calcium dolomite or calcite.Furthermore,it is proposed that fine to medium crystalline dolomite has better chance to develop pore and to receive stronger burial dissolution,eventually to become large scale and high quality reservoir,which is an important target of hydrocarbon exploration in deep burial realm.