重复压裂造缝机理研究

从岩石破坏基本机制入手,研究重复压裂造缝机理。通过分析目的井层天然裂缝分布特征、地应力场和岩石力学特征以及射孔完井工艺、开采因素、压裂工艺等对于重复压裂造缝的影响,给出了具有天然裂缝低渗透储层重复压裂造新缝的理论判据。以安塞油田王窑区块为例,进行了具体实例分析。结果表明,裂缝转向并不等同于地应力场转向,即便地应力场不发生变化,也可通过采取其他合适的压裂措施或工艺来实现裂缝转向。

Fracture initiation mechanism of refracturing

The fracture initiation mechanism of refracturing was investigated by discussing rock failures.Both the objective and subjective effects such as distribution of natural fracture,geostress field,mechanical characteristics,and physical properties of rock,well-completion methods,injection/production and fracturing technology upon rock failures were taken into account.As a result,the theoretical criteria for fracture reorientation were given,namely the critical bottomhole pressure and the conditions of geostress field and mechanical parameters of rock.Based on the above criteria,a typical well was analyzed by use of the refracturing data of Chang 6 formation in Wangyao section of Ansai oilfield.It was shown that the fracture reorientation was not equivalent to that of the geostress field and it could also be achieved by proper fracturing technology or approaches even if the geostress field remained constant.