复杂裂缝支撑剂转向规律研究

复杂裂缝技术是页岩等非常规油气藏成功开发的关键之一,目前研究大多针对如何提高缝网复杂度,对于复杂裂缝形成后支撑剂能否进入各级分支缝的问题仍不明晰,数值模拟、室内实验提供了部分定性认识,但缺乏归纳总结形成定量规律,特别是还没有工程可用的数学模型为支撑剂粒径、压裂液排量选取提供理论依据。基于此研究现状,本文针对多级、多尺度复杂裂缝系统,提出液量分配模型以及支撑剂转向输运条件,对支撑剂在复杂裂缝内的输运行为进行预测,并采用数值模拟对模型进行验证,结果显示相较于前人模型,本文模型的预测精度更高。同时澄清了分支裂缝夹角对于液量分配的影响本质是对于分支裂缝缝宽的影响。最后应用该模型定量研究了天然裂缝开启程度对于压裂液分配情况以及支撑剂输运效果的影响,为现场支撑剂粒径、压裂液排量选取提供理论依据。

Liquid distribution model and proppant turning law of complex fractures

Complex fracture technology is one of the keys to the successful development of unconventional oil and gas reservoirs such as shale. At present, most studies focus on how to improve the complexity of fracture network. It is still unclear whether proppant can enter branch fractures at all levels after the complex fractures are formed. Numerical simulation and indoor experiments provide some qualitative results, but there are still lack of quantitative models. Thus, the liquid distribution model and the proppant turning law are proposed in this paper to predict the proppant transportation behavior in the complex fractures. The results show that the prediction accuracy of this model is higher than that of previous ones. In addition, the influence of branch fracture angle on the liquid distribution is discussed. Finally, an engineering case is studied with this model, and some suggestions are provided for the fracturing parameter optimization.