水力压裂支撑裂缝导流能力计算与分析

Calculation and analysis of the propped fracture conductivity created by hydraulic fracturing

水力压裂已广泛用于油气藏开发,而裂缝导流能力是压裂优化设计的重要指标。目前很少有研究涉及到楔形裂缝的导流能力,而水力压裂后裂缝多呈现为近井筒处开口大,远井筒处开口小的楔形。在考虑支撑剂嵌入、裂缝形态(楔形)的基础上,建立了支撑裂缝导流能力计算模型,通过与文献中的数据对比验证了模型的准确性,并分析了关键参数对裂缝导流能力的影响。结果表明:沿着裂缝远离井筒,导流能力降低,降低趋势为裂缝跟端附近降低快、趾端附近降低慢;支撑剂嵌入导致有效流动空间减小、裂缝导流能力降低;裂缝宽度一定时,支撑剂越小,裂缝有效流动空间越小,导流能力越低。该文提出的支撑裂缝导流能力计算模型很容易嵌入到压裂数值模拟软件中,具有广泛的应用前景。

Hydraulic fracturing has been widely used in oil and gas reservoir development,and the fracture con⁃ductivity is an important indicator of the fracturing optimization design.Currently,there are few studies on the con⁃ductivity of the wedge⁃shaped fractures.However,the fractures width after hydraulic fracturing is mostly large near the wellbore and small far away from the wellbore in the form of wedge.Considering the proppant embedded and fracture shapes(wedge⁃shape fracture),a calculation model of the propped fracture conductivity was established.The accuracy of the model was verified by the comparison with the data in the literature,and moreover the effects of the key parameters on the conductivity were analyzed.The results show that the conductivity decreases along the fracture away from the wellbore,and the decreasing trend is that the conductivity decreases rapidly near the heel end of the fracture and slowly near the toe end of the fracture.The proppant embedding reduces the effective flow space and fracture conductivity.When the fracture width is constant,the smaller the proppant size,the smaller the effective flow space of the fracture,and the lower the conductivity.The proposed calculation model of the propped fracture conductivity can be easily embedded in the fracturing numerical simulation software,which has a wide application prospect.