致密油藏压裂开发流固耦合数值模拟

为揭示了致密油藏在压裂与开采过程中孔缝介质的变形规律,研究流固耦合作用对致密油藏生产动态的影响,本文基于致密砂岩储层孔缝多重介质变形力学机制,阐述了致密油藏压裂与采出过程中的流固耦合作用,针对不同开发阶段孔缝介质变形及流体渗流特征,建立了相应的物性参数动态变化模型及多相流渗流数学模型,并编制了致密油藏压裂、开采数值模拟软件对典型致密油区块进行了数值模拟。结果表明,压裂液注入过程中,基质孔隙膨胀,孔、渗物性增大;高于开启压力时,天然裂缝开启并逐步延伸;高于破裂压力时,岩石破裂形成人工裂缝,储层渗透率大幅升高。在生产过程中,随着地层流体压力的降低,基质孔隙收缩,裂缝开度变窄;当低于闭合压力时,裂缝闭合导致储层渗透率显著的降低。

Coupled Analysis of Flow and Deformation in Tight Oil Reservoir Fracturing and Production Simulation

In order to reveal the deformation law of multi-media in different development stages in tight oil reservoir and study the effect of coupling of flow and deformation interaction on reservoir performances. The coupling of multiphase flow and reservoir deformation during fracturing and production was stated, based on the mechanics mechanism of multi-media deformation on tight sandstone reservoir, the dynamic model of reservoir parameters for different development stages and the multiphase seepage mathematical model were established. On this basis, an integration of fracturing and production software module was developed. The simulation results show that the pore expanded and the nature fracture opened once the injection pressure was higher than the opening pressure and the artificial fracture formed once the pressure was higher than the formation fracture pressure, as a result the reservoir porosity and permeability significantly increased in fracturing process. In the production process, since the decrease of pressure, the pore shrank and the fracture closed once the pressure was lower than the closing pressure, consequently the reservoir permeability decreased sharply.