An evaluation method of volume fracturing effects for vertical wells in low permeability reservoirs

• 作者: CHEN Ting HE Ying LI Xiaoshan LUO Yutian XIA Debin YANG Zhengming ZHANG Anshun ZHANG Yapu ZHAO Xinli
• 来源期刊: 石油勘探与开发:英文版
• 学科: 工学
• 关键词: volume fracturing fracturing effect evaluation fracturing area CONDUCTIVITY low permeability reservoir vertical well
• 年，卷（期）: 2020,（2）
• 页码范围: 441-448
• 页数: 8页
• 分类号: TE357

摘要

To evaluate the fracturing effect and dynamic change process after volume fracturing with vertical wells in low permeability oil reservoirs, an oil-water two-phase flow model and a well model are built. On this basis, an evaluation method of fracturing effect based on production data and fracturing fluid backflow data is established, and the method is used to analyze some field cases. The vicinity area of main fracture after fracturing is divided into different stimulated regions. The permeability and area of different regions are used to characterize the stimulation strength and scale of the fracture network. The conductivity of stimulated region is defined as the product of the permeability and area of the stimulated region. Through parameter sensitivity analysis, it is found that half-length of the fracture and the permeability of the core area mainly affect the flow law near the well, that is, the early stage of production;while matrix permeability mainly affects the flow law at the far end of the fracture. Taking a typical old well in Changqing Oilfield as an example, the fracturing effect and its changes after two rounds of volume fracturing in this well are evaluated. It is found that with the increase of production time after the first volume fracturing, the permeability and conductivity of stimulated area gradually decreased, and the fracturing effect gradually decreased until disappeared;after the second volume fracturing, the permeability and conductivity of stimulated area increased significantly again.