体积压裂技术的发展正处于起步阶段,国内多个油田进行了大型水力压裂尝试,其中最典型的是长庆油田实施的分段多簇压裂技术。体积压裂渗流理论发展相比工艺具有滞后性,目前尚未有完善的用于现场指导的渗流理论体系。本研究以矿场体积压裂直井的微地震测试资料为依据,建立了可以描述其渗流规律的数学模型:首先将渗流过程分为油藏到主裂缝的流动和主裂缝内部流动;然后利用达西渗流理论描述主裂缝稳态渗流过程,利用源函数与叠加原理描述油藏渗流过程;最后在主裂缝壁面处进行油藏渗流与主裂缝渗流的耦合。经过数学求解后得到了该模型井底压力的特征曲线,并且分析了各种因素下该特征曲线的变化规律。对该数学模型和数值模型的结果进行比对,证实了该模型的准确性。
The development of volume fracturing technique is still in its infancy. A large number of domestic oilfields have attempted ways of hydraulic fracturing, among which Changqing oilfield has made great progress by developing a new technique named segmented multi-cluster fracturing. As the seepage flow mechanism of volume fractured reservoir is still far from perfection, this article tries to propose a basic model for volume fractured vertical wells, which is based on the concept of SRV. Firstly, the seepage flow underground is divided into two processes:seepage flow in reservoir and seepage flow in fracture. Then the seepage in reservoir is studied with Green function and line source function, while the seepage in fracture is assumed as the Darcy flow. Finally, the two processes are coupled at the fracture surface with equivalent pressure and flow rates. The pressure and pressure derivative type curves are obtained by solving flow matrix equations, and the factors related to the type curve are studied. In the end this model is proven to be an efficient model coupling vertical fractured wells, two porosity system and radial composite reservoir, which is a foundation for pressure transient analysis of volume fractured wells.
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