陆相致密气井一体化压后评价方法研究

Study on Integrated Post Pressure Evaluation Method for Tight Gas Wells

摘要: 陆相致密气井在利用压裂施工数据进行压后反演时，存在停泵时间短、裂缝闭合点难以获取等问题，开展试井解释易出现线性流特征不明、多解性强等问题。针对上述问题，在地质工程一体化压裂数值模型中正演计算现场施工条件下的裂缝参数及地层压力；利用压裂施工数据反演计算裂缝参数及地层压力，同时开展试井解释，将正演得到的地层压力 ± 10 MPa作为约束条件，反演计算裂缝参数、地层压力；取试井解释与压裂施工数据反演的结果参数的均值作为输入参数修正约束条件，循环迭代；当压裂施工数据反演与试井解释结果误差 ≤ 5%时，循环停止。基于一体化的压后评价方法有效地降低了解释模型的多解性以及解释结果的偏差，满足陆相致密气井压后评价的技术需求。

Abstract: When using fracturing construction data for evaluation after fracturing, there are problems such as short pump shutdown time and difficult to obtain fracture closure point. When using well test interpretation, it is easy to have some problems, such as the early linear flow characteristic is not obvious and the multi-solution is strong. To solve the above problems, the fracture parameters and formation pressure under the pump sequence are calculated in the numerical fracturing model integrated with the integration of geology and engineering. The fracture parameters and formation pressure were calculated by inversion of fracturing construction data. In the meanwhile, pressure test interpretation was carried out. The formation pressure ±10 MPa obtained by forward calculation was taken as the constraint condition. The mean value of formation pressure derived from well test interpretation and fracturing construction data is taken as the constraint condition of the input parameters to modify the forward and inversion models. When the relative error between the fracture parameters obtained from the inversion of fracturing construction data and the interpretation results of well testing is less than 5%, the cycle stops. The integrated post-fracturing evaluation method effectively reduces the non-uniqueness of the interpretation model and the bias in interpretation results. And the results can meet the technical requirements of understanding after fracturing of the tight gas well.