压裂致密油藏产能递减分析方法

致密油储层自然渗透率低,孔隙结构细小、流体流动难度大,一般采用压裂井衰竭开发方式。压裂后储层将形成裂缝、基质两种渗流介质。在综合考虑介质类型及不同介质渗流能力基础上,结合物质平衡方程及产能方程,建立了压裂致密油储层的产量递减模型。实例分析表明,产量递减模型与生产动态数据吻合度较高;而常规Arps递减由于没有考虑基质与裂缝的差异性,递减曲线与生产动态数据吻合度相对较低。因此,该方法可以用于压裂致密油藏产能递减规律的分析。

Research on the Declining Mode of Fractured Tight Oil Reservoirs

Tight oil reservoirs have the characteristics of low natural permeability and micro pore structure resulting in the resistance in fluid percolation and the difficulty in waterflooding, and depletion drive development with fracturing are frequently adopted. The fractured tight oil reservoirs will form fracture and matrix two reservoir medium with two percolation systems respectively. Considering that the percolation capacity of the matrix is much smaller than that of the fracture, the reservoir percolation characteristics completely differ from the single medium reservoir. Based on the comprehensive consideration of the medium type and the percolation capacity of different medium, the production decline model of the fractured tight oil reservoirs is deduced theoretically through combining the material balance equation and the productivity equation. The case analysis shows that the method in this paper is in good agreement with the production dynamic data. Conventional Arps decline does not take into account the difference between matrix and fracture, and the consistency between decline curve and production dynamic data is relatively low. Therefore, this method can be used to analyze the productivity decline rule of fractured tight reservoirs.