清水压裂裂缝闭合形态的力学分析

MECHANICAL ANALYSIS OF CLOSING SHAPEOF CRACK INDUCED BY WATERFRAC TREATMENT

近年来,清水压裂以其现场施工简单、压裂成本低等优点受到人们的广泛关注,并且在一些低渗透油层已经取得了明显的压裂增产效果。尽管人们已经认识到清水压裂的效果主要来源于裂缝面的粗糙性和相对剪切错动,但对于清水压裂裂缝的闭合形态等理论问题研究得不多,也缺乏有效的理论指导现场施工。在充分调研国内外相关文献的基础上,从分析清水压裂的裂缝特征入手,从力学角度就清水压裂的裂缝闭合形态等问题进行分析研究,建立清水压裂情况下局部裂缝张开、裂缝面错动和裂缝面抗剪能力的计算模型,深入揭示清水压裂油井增产的机制和原因,为今后清水压裂施工设计提供理论依据。

In recent years,extensive attention is poured into the waterfrac treatment for its simple application and low fracturing costs,and it has already made an obvious effect to increase the yield for the fracturing in some low permeability reservoirs.It is well known that the effect on waterfrac treatment mainly comes from the roughness and relative shear moving in the crack surfaces,but the theoretical researches are not so many on the crack closing shape of waterfrac treatment,and there are not some effective theories to guide the construction in oil field.Based on the full inspection of the relevant literature at home and abroad,the fracture characteristic is analyzed for the waterface treatment and the crack closing shape is analyzed with the mechanical methods.The shear strength models are established for waterfrac treatment under the partial crack opening and shear moving of the crack surface.It reveals the mechanism and the reasons for increasing well production from waterfrac treatment and it will also provide a theoretical basis for the future constructional design in waterface treatment.