应用位势理论和叠加原理,考虑裂缝无限导流与有限导流2种情况,推导分段多簇压裂水平井的产能线性方程组并采用数值分析方法进行求解,得到每簇裂缝的产量及水平井总产量,并通过实例计算分析压裂水平井产能分布及裂缝参数对其影响。裂缝无限导流时,总产量随所有裂缝半长的减小明显下降,水平井两端的外侧裂缝对总产量贡献最高,同一段内的裂缝,中间裂缝对产量的贡献明显比两侧低;裂缝有限导流时,水平井两端的外侧裂缝对总产量的贡献减小,同一段内的裂缝,中间裂缝对总产量的贡献明显增大,但产量分布的总体规律与无限导流时相同;裂缝导流能力对产能的影响比较大,但两者之间并非线性关系;水平井分3段进行压裂、每段2簇即可保证较高产量,压裂设计时应尽量增加裂缝半长与导流能力,重点是水平井两端的外侧裂缝,裂缝导流能力存在最佳值。
Applying the potential theory and the superposition principle, the authors derived the linear productivity equations of staged multi-cluster fractured horizontal well considering finite and infinite conductivity fractures, respectively. The cluster yields and total yield were obtained by solving these equations numerically. A concrete example is used to analyze the productivity distribution of the fractured horizontal well and the influence of fracture parameters on it. When the fracture conductivities are infinite, the total productivity decreases significantly with the decrease of all fractures' half-lengths; outer fractures near the endpoints of the horizontal wells contribute most to the total productivity, and fractures on the edges contribute more than the middle ones within the same stage. When the fracture conductivities are finite, the contribution of outer fractures near the endpoints of the horizontal wells to the total productivity decreases, and the contribution of middle fractures within each stage increases significantly, but the overall distribution characteristics are in accord with the former case. Fracture conductivities have a great influence on the productivity, but they are not linearly correlated. Three stages and two clusters per stage can ensure high productivity, and during fracturing design, one should try to increase fracture half-lengths and fracture conductivities, especially for outer fractures near the endpoints of the horizontal well, and there exists an optimal value for the fracture conductivities.