Numerical Simulation Of Shale Condensate Reservoirs Considering Confinement Effect

Conventional oil and gas resources can no longer meet the demand for oil and gas resources for social development,and the large-scale development of unconventional oil and gas has important strategic significance in ensuring national energy security and sustainable social development.Shale condensate reservoirs are a special kind of unconventional oil and gas reservoirs,and in recent years,the exploration and production of shale condensate reservoirs have become economical by establishing multi-stage fracturing along horizontal wells.However,the diversified reservoir mode,complex reservoir pore structure and complex multi-scale phase state make it difficult to develop shale condensate gas reservoirs efficiently.Therefore,it is important to investigate the numerical simulation of shale condensate gas reservoirs considering the confinement effect.In this study,firstly,a numerical model of multi-stage fractured horizontal wells in shale condensate reservoirs is established by reservoir numerical simulation software.Secondly,a numerical model of multi-stage fractured horizontal wells in shale condensate reservoirs with coupled confinement effect is developed to study the phase change of condensate gas under the influence of restricted area effect.And the numerical model of multi-stage fractured horizontal wells in shale condensate reservoirs is coupled with adsorption and diffusion effects to test and analyze the effects on the production behavior of shale condensate reservoirs respectively.Finally,based on the established numerical model of shale condensate reservoir considering the confinement effect,single-well gas huff and puff simulation is conducted,including optimization of huff and puff media,sensitivity analysis of gas reservoir single factor,and optimization of work system.The results of the study show that when considering the confinement effect,the phase envelope shrinks,the single-phase flow time is longer,and the condensate production increases significantly;when considering the confinement effect,adsorption effect and diffusion effect respectively,the cumulative oil production increases,but the confinement effect is more important,so the confinement effect cannot be ignored;the CO₂ injection and huff and puff method of shale condensate reservoir considering the confinement effect has better development effect than dry gas injection and N₂ huff and puff;the optimal parameters of CO₂ huff and puff:injection volume of 80×10⁴-100×10⁴ m³,injection rate of 20,000 m³/day,stall time of 7 days,huff and puff rounds of 2,production time of 270 days.The degree of condensate recovery was improved by 0.744%compared to depletion extraction.The study provides theoretical support for the efficient development of shale condensate reservoirs.