不同孔-缝-洞组合碳酸盐岩储层气水两相孔隙尺度流动模拟

Pore-scale Simulation of Gas-water Two Phase Flow in Carbonate Reservoir with Different Combinations of Pore,Network and Hole

碳酸盐岩储层孔缝洞组合类型多样,从孔隙尺度刻画和认识气水两相在不同类型储层中的流动规律具有重要的科学意义。建立了适用于深层碳酸盐岩储层气水两相流动的多松弛颜色梯度格子玻尔兹曼模型(LBM),实现了气水两相在多孔介质中的可视化模拟,揭示了成藏过程(气驱水)和水侵过程(水驱气)不同孔缝洞组合流动通道中的气水两相动态流动行为。研究表明,碳酸盐岩气藏成藏过程中主要存在的残余水类型有盲端孔隙水、洞穴边部残余水、水膜水、“H型”残余水和网状残余水;水侵过程中,主要存在的封闭气类型有盲端孔隙封闭气、变径卡断气、绕流封闭气、“H型”封闭气和网状封闭气;由于洞穴体积较大,成藏和水侵过程中缝洞型储层残余水饱和度和封闭气饱和度均最大;裂缝型和缝洞型储层的气相渗流能力随含水饱和度变化波动明显,呈非线性变化规律。研究成果可为深层碳酸盐岩气藏微观渗流、水侵动态预测等提供理论支撑。

There are various combinations of pore,network and hole in carbonate reservoir.It is of great significance to understand and characterize the gas-water two phase flow in these different types of reservoirs.A multi-relaxation color-gradient lattice Boltzmann method(LBM)in adaption to the deep-reservoir condition of carbonate reservoir is proposed.Based on the method,the gas-water two phase flow behaviors for different types of carbonate reservoirs under gas accumulation process(gas displacing water)and water invasion process(water displacing gas)are revealed.The results show that,the types of residue water during gas accumulation process include water in dead-end pore,water in side of hole,water film,water in“H”shape and network shape;the types of enclosed gas during water invasion process include gas in dead-end pore,snap off gas,gas enclosed by bypass,gas in“H”shape and network shape.Because the large volume of holes,the residue water(gas accumulation process)or enclosed gas(water invasion process)of network-hole reservoir is highest compared with other two types of carbonate reservoirs.For network reservoir and pore-hole reservoir,with the change of water saturation,the gas percolation capability is fluctuated instead of linear change with water saturation.This work can be a good support for the development of micro-percolation theory and water-invasion-prediction theory for deep carbonate gas reservoir.