复杂裂缝产生机理研究

Forming mechanism of complicated fractures in hydraulic fracturing

目前的水力压裂理论多数是建立在单裂缝延伸基础之上的,这种假设在大多数情况下都能满足工程实践的需要。随着储层改造复杂性的增加和认识手段的提高,逐渐认识到有复杂的裂缝形态存在,包括转向裂缝、鱼刺状小裂缝、不同方位的多裂缝、同方位的多裂缝及纵向上的多裂缝等。这些复杂的裂缝形态与裂缝尺寸、改造效果及压裂施工的成败直接相关。结合射孔方式、地层特点、地应力结构及裂缝产生的微观过程,阐述了各种裂缝形态的产生条件,从而提高压裂设计的针对性与压裂施工的成功率。

Most of hydraulic fracturing theories are all on the basis of single fracture extension at present. The hypotheses that there is only one fracture in hydraulic fracturing can satisfy the requirement of engineering practice in majority case. With the increasing of reservoir complexity and the improving of recognition instrument, the existing of complicated fracture morphology, including turnning crack, fish bone crackle, multi-hydrauli fractures in different azimuths or same azimuths or in highly asymmetrical machine direction, are cognized, which is ralated to the fissured size and fracturing effect. This article combines the perforation mode, formation fearures, terrestrial stress structure and microscopic course. The paper expounds the forming condition of different kinds of fracture morphology, which can improve the pertinence of fracturing design and the success rate during hydraulic fracturing operation.