关键词: 致密油气藏, 分层压裂, 多层合试, 裂缝导流能力, 试井分析

Abstract: Fracturing of vertical well and multi stage fracturing of horizontal well are the two main methods for developing tight oil/gas reservoirs, but few studies have focused on fracture parameter interpretation with non-uniform conductivity of multi-layer tight oil/gas reservoirs in multi-layer fracturing and commingling production wells. Therefore, the non-uniform conductivity of hydraulic fractures caused by differential fracture propagation during multi-layer fracturing is considered rather than the traditional scenario of uniform fracture conductivity of tight reservoirs. The well testing analysis model for non-uniform fracture conductivity of multi-layer tight oil/gas reservoirs in multi-layer fracturing well is established by using Laplace spatial transformation, Duhamel superposition principle and Stehfest numerical inversion method. In addition, the well testing type curve analyzing the flow regimes in multi-layer fractured well is researched and the influence of several factors on fluid flow laws is determined, including the wellbore storage capacity, fracture skin factor, fracture conductivity and reservoir properties. The results show that: (1) The fluid flow in multi-layer tight reservoir in multi-layer fracturing well is divided into five stages, in which the early flow regime is affected by wellbore storage capacity and fracture skin factor, and the mid-term flow regime is controlled by hydraulic fracture length and conductivity; (2) Given the same production pressure difference, the larger fracture length and higher fracture conductivity are beneficial to increase well production; (3) The pressure drop in hydraulic fracture zone will be underestimated and the early well production capacity will be overestimated if fracture conductivity and non-uniform fracture propagation are ignored. Finally, a case study of well testing interpretation is given and the hydraulic fracture parameters of each layer are obtained.