碳酸盐岩, 重结晶, 流体压力, 孔隙演化

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