各向异性地层重复压裂最优时机及影响因素分析

依据低渗透储层力学参数和渗流特点,建立了考虑地层各向异性的固-液耦合最佳重复压裂时机模型,提出了等应力点的概念。对多因素影响下的最佳重复压裂时机的研究表明,远场水平地应力差较小、弹性模量较大、初次裂缝长度和宽度较大、低渗透、初次改造后平均生产压差较大等影响因素对重复压裂产生新缝有利。将影响因素分为3类:①产生重复压裂新裂缝的影响因素;②仅影响最优重复压裂时机的因素;③可以忽略的因素。

Study on optimal re-fracturing timing in anisotropic formation and its influencing factors

Based on the mechanical properties and porous flow parameters of low permeability reservoir,an optimal re-fracturing timing model considering solid-fluid coupling in anisotropic formation was established,and the concept of equal stress point was proposed. The small stress difference,large elastic modulus,large length and width of initial fracture, low permeability, and large pressure drawdown are the favorable factors for creation of new fractures in re-fracturing. Those influencing factors are further classified into three groups: ①the factors for deciding whether new fracture be created; ②the factors only affecting the optimal re-fracturing timing; ③the negligible factors.