Fracture prediction modeling of reef limestone reservoirs in south China Sea

Liuhua oilfield was a deep-water reef limestone heavy oilfield in south China Sea and had characteristics of complicated sediment environment,big structure uncertainty,big difficulty in reservoir property evaluation,strong anisotropy,developed fractures and dual porosity media.In order to make a study on distribution characteristics of reservoir fractures,based on depositional evolution of reef limestone and facies classification,by fully using coring,seismic,drilling and imaging logging,the fracture network model of the reef limestone reservoirs was established.The results indicated pressolution and dissolution seams with low angle and bigger crack opening were mainly developed in reef facies,while group seams with high angle were developed in beach facies,which was focused on the tectonic joints and tectonic soluble seams,with superiority striking in north west-south east.The influencing factors of the reef limestone fracture development in Liuhua oilfield included both the structural factors and the later diagenesis.The comparison between the research results and the dynamic status showed the method could provide good guidance for oilfield development.