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.

The development of stress finite element analysis approach based on 3D corner-point grid can establish accurate crustal stress field. Firstly, corner-point grid is employed to establish the detailed structure and attribute model of reservoir. Secondly, grid conversion algorithm is applied to convert corner-point grid to corresponding finite-element grid. Then, finite element analysis is used to get attribute model based on finite-element grid which reflects the distribution of crustal stress. Lastly, grid conversion algorithm is operated to reverse the attribute model to another format which is based on corner-point grid for subsequent analysis. Thus, the procedure continuity and data consistency has been proved by this approach. Furthermore, real data collected from oilfield X and Y are employed to simulate stress distribution and the validity and accuracy of the proposed approach can be verified by comparison between simulation results and real data.