基于各向异性扩散方程的页岩气井改造体积计算模型

超低渗透率页岩储层需要通过分段多簇大规模体积压裂形成水力裂缝与天然裂缝相互交织的复杂裂缝网络实现气井产能最大化,且微地震反演裂缝证明,许多页岩储层可以形成裂缝网络。页岩气藏的矿场压裂实践表明,储层改造体积是影响页岩压后效果的重要参数。基于流体扩散方程和岩石破坏准则,建立了一种针对均质各向异性孔隙弹性介质的改造体积计算模型。基于实例井,运用解析模型对改造体积进行了计算。结合微地震监测结果与离散裂缝网络法,进行计算对比分析。结果表明,所提方法的计算误差小,可运用于页岩压裂矿场改造体积计算评价,对完善页岩改造和压后评价理论具有重要意义。

CALCULATING MODEL OF THE SHALE-GAS-WELL SRV BASED ON ANISOTROPIC DIFFUSION EQUATION

The productivity of the gas well can be maximized in the ultra-low-permeability shale reservoirs with the help of the staged multi-cluster large-scaled volume fracturing establishing interconnected complex fracture network between the hydraulic and natural fractures;and moreover the micro-seismic inversion has improved that the fracture network can be developed for many kinds of the shale reservoirs.The field fracturing practices of the shale gas reservoirs show that the simulated reservoir volume (SRV) is the key parameter of influencing the post-frac effects.By means of the flow diffusion equation and rock failure criterion,the SRV calculating model was established for the homogeneous anisotropic elastic media.Based on the case study wells,with the help of the analytical model,the stimulated volume was calculated.Integrating with the micro-seismic monitored results and discrete fracture network method,the computation and contrast were conducted.The research achievements prove that the calculated error is pretty small for the developed method,and furthermore the method can be applied to calculate and evaluate the field stimulated volume of the shale fracturing,so it is very significant to perfect the shale stimulating and post-frac evaluating theories.