Study On Seepage Characteristics And The Influence Of Heterogeneity On Development Of Carbonate Gas Reservoirs

The complex pore structure of carbonate gas reservoirs is one of the key factors restricting the efficient development of deep carbonate gas reservoirs.However,the current research on pore structure and its impact is not intuitive and in-depth.The research on the three-dimensional visualization of gas flow and the effects of cracks and holes on gas well productivity needs to be improved.Therefore,researches on the influence of pore structure on seepage characteristics and utilization of gas reservoirs have been carried out to guide the efficient development of carbonate gas reservoirs.First,two types of CT scans were used to analyze the pore structure characteristics of the three types of carbonate cores;then,the gas flow characteristics experiments under formation conditions were used to study their flow laws;then,the digital core software PerGeos was used to analyze the different The single-phase flow and gas-water two-phase seepage simulation were carried out for the type core.Finally,the effects of interlayer heterogeneity and intralayer heterogeneity on development were studied through improved series-parallel failure simulation experiments under high temperature and pressure conditions.The results show: that the permeability is mainly affected by the degree of fracture development and distribution characteristics,and pore connectivity;in the pore structure with weak connectivity,the continuity of gas flow is poor,and the gas velocity and permeability are low.The existence of large pores and holes with a quantity of less than30% has greatly increased the porosity of the reservoir.The numerical simulation obtained a visualization model of gas flow in three-dimensional pore structure and three relative permeability curves,reflecting the influence of cracks and pores on relative permeability.In the development of carbonate gas reservoirs,the multi-layer combined production should control the extremely poor permeability between the layers to prevent the interference of channeling flow on the development;the reasonable production method should be selected in the layer according to the gas flow characteristics in different pore structures Promote the coordinated development of gas reservoirs in the horizontal direction.