In order to investigate the micro-mechanism of carbonate recrystallisation and its reservoir geological significance, based on the theory of carbonate recrystallisation and the latest research results, the effects of temperature, pressure and fluid composition on the mineral crystal-pore fluid reaction are investigated, and a geological-mathematical model is constructed to elucidate the relationship between recrystallisation and the physical parameters of carbonate rocks. The findings unveil the recrystallization in carbonate rocks as a microscopic process characterized by dissolution-precipitation and the stabilization of rock mineral phases. This process is markedly influenced by various factors, including temperature, pressure, and fluid solutes. By modulating the grain size and morphology of carbonate minerals, recrystallization plays a pivotal role in adjusting pore structure parameters, such as pore tortuosity and pore-throat radius ratio, ultimately enhancing the permeability of the rock porous medium. Moreover, this study introduces a recrystallization-rock property co-evolution model, delineating the impact of different diagenetic environmental conditions. Notably, fluid pressure emerges as a pivotal factor governing the preservation and adjustment of pore structure during the recrystallization process. In closed fluid overpressure systems, recrystallization tends to yield euhedral crystal structures in carbonate minerals, thereby favoring better preservation of rock porosity. Conversely, open fluid normal pressure systems tend to induce the formation of dense interlocking rock structures, leading to the impairment of pore structure and seepage capacity.

carbonate rock, recrystallization, fluid pressure, pore evolution

为探究碳酸盐岩重结晶作用的微观机理及其储层地质意义, 基于碳酸盐岩重结晶作用相关理论和最新研究成果, 探讨温度、压力和流体成分等因素对矿物晶体–孔隙流体反应的影响, 并构建地质–数学模型来阐明重结晶作用与碳酸盐岩物性参数间的关系。结果表明, 碳酸盐岩重结晶作用是一系列微观尺度的溶解–再沉淀以及岩石矿物相趋于稳定的过程, 受温度、压力和流体溶质等多种因素的影响。重结晶作用通过改变碳酸盐矿物的粒度及自形程度来调整孔隙迂曲度和孔喉半径比等孔隙结构参数, 从而达到改善岩石多孔介质渗流能力的效果。此外, 基于不同成岩环境条件构建重结晶–岩石物性协同演变模式, 发现流体压力是影响重结晶作用过程中孔隙结构保存及调整的关键因素, 表现为封闭的流体超压体系中碳酸盐矿物在重结晶作用下趋于形成自形晶体结构, 岩石孔隙保存较好; 开放的流体常压体系中碳酸盐岩趋于形成致密镶嵌的岩石结构, 孔隙结构和储渗能力均遭到破坏。

碳酸盐岩, 重结晶, 流体压力, 孔隙演化