基于有限元模拟的表面活性剂压裂吞吐参数优化方法研究

Optimization of Surfactant Stimulation Parameters Based on Finite Element Simulation

表面活性剂吞吐开发低渗透油藏,可以改善地层流体在多孔介质中流动能力。低渗透油藏一般都经压裂开发,因此低渗透油藏表面活性剂吞吐必然涉及裂缝内流体的滤失、地层内的达西流动以及地层多孔弹性能释放等因素。为了研究低渗透油藏表面活性剂压裂吞吐特征,模拟了表面活性剂吞吐过程中地层内流体流动规律,研究了注入过程中注入压力和注入流量之间的对应关系。结果表明:累计注入量、孔隙度对地层压力的变化影响较大;当裂缝半径高于15m时,注入压力下降幅度变缓,表明对于具有一定裂缝规模的吞吐井,日注入量较低时无须增加其裂缝半径;当裂缝渗透率高于0.5μm^(2)时,井底注入压力几乎不变,说明对于低渗透率油藏日注入量较低的井其导流能力可控制在0.5μm^(2)左右。

Surfactant stimulation can improve the flow ability of formation fluids in porous media to develop low permeability reservoirs. Low permeability reservoirs are generally developed by fracturing, so surfactant stimulation in low permeability reservoirs must involve such factors as fluid filtration in fractures, Darcy flow in formations and release of porous elastic energy in formations. In order to study the stimulation characteristics of surfactant in low permeability reservoir, the flow pattern of fluid in the formation during surfactant stimulation was simulated, and the relationship between injection pressure and injection flow rate during injection was studied. The results showed that the cumulative injection amount and porosity had great influence on the formation pressure. When the fracture radius was higher than 15 m, the injection pressure decreased slowly, indicating that for the stimulation wells with a certain fracture size, there was no need to increase the fracture radius when the daily injection volume was low. When the fracture permeability was higher than 0.5 μm^(2), the bottom-hole injection pressure was almost unchanged, indicating that for wells with a low daily injection rate in low-permeability reservoirs, their conductivity could be kept around 0.5 μm^(2).