基于压裂液返排数据的页岩油气藏裂缝参数反演方法

Inverse method based on fracturing fluid flowback data for estimating fracture properties in shale reservoirs

为及时评价水平井压裂效果、准确反演裂缝参数,提出基于页岩油气藏压裂液返排数据的裂缝参数反演方法。以不稳定渗流理论为基础,考虑裂缝—基质间油水或气水两相复合流动,以及流体在储层中的复杂渗流机理,建立渗流数学模型并进行半解析求解,形成一套划分两相流动阶段的诊断曲线和反演裂缝参数的直线分析法,对半解析模型进行数值模拟验证。美国Marcellus页岩气藏压裂井返排数据分析结果表明,该方法能够准确反演裂缝初始孔隙体积和渗透率,在裂缝参数反演方面具有实用性。

To evaluate the hydraulic fracturing performance and estimate fracture properties,an inverse analysis method by analyzing flowback data right after well stimulation in shale reservoirs is proposed.This method includes a mathematical model for flowback period,a diagnostic plot for flow regime analysis,and a straight-line analysis approach for estimating fracture properties.The mathematical model considers the coupled two-phase flow in the fracture and matrix system and is solved semi-analytically,which is validated by numerical simulation.The flowback data from a multi-fractured horizontal well in Marcellus Shale Gas Reservoir,USA,are analyzed in the field case study,which proves the applicability and robustness of this method in estimating initial fracture pore-volume and permeability.It is practical in fracture parameter inversion.