考虑天然裂缝成簇分布的压裂液滤失研究

摘要/Abstract

摘要：

对于天然裂缝发育的储层,压裂过程中压裂液的滤失对水力裂缝尺寸、支撑剂分布以及地层污染情况都有着较大影响。目前考虑天然裂缝影响的压裂液滤失模型,都忽略了天然裂缝成簇分布的特征,从而导致模型存在局限性。通过倍增串级方法建立了二维分形离散裂缝网络模型,合理地表征了天然裂缝成簇分布的特征;通过对裂缝孔隙介质网格单元进行剖分,将裂缝网络转化为各向异性的等效连续介质模型;最后建立了基于渗透率张量的裂缝性储层压裂液滤失模型。计算结果表明：天然裂缝发育带的走向在宏观上决定了压裂液的滤失方向和压力波的传播方向;压裂液会沿着长裂缝进行滤失,建议压裂施工时应提前对水力裂缝壁面的天然裂缝进行封堵;压裂液黏度对滤失速度也有一定的影响。

关键词: 压裂液滤失, 裂缝网络, 成簇分布, 倍增串级, 渗透率张量

Abstract:

The fracturing fluid leak-off in the reservoirs with developed natural fractures had a comparatively great influence on hydraulic fracture structure, proppant distribution and formation contamination. However, the current mathematical model for fracturing fluid leak-off considering natural fractures almost ignored or simplified the clustered distributed natural fractures, which limited the applications of these models. So firstly, by the multiplicative cascade method, we established a two-dimensional fractal discrete fracture networks model which reasonably showed the clustered distribution of natural fractures. Then, the established fracture networks were transformed into homogeneous anisotropic equivalent continuum media through subdividing the fractured porous domain into small elements. Ultimately, a mathematical model of fracturing fluid leak-off in fractured reservoir was established based on the permeability tensor. The results showed that the the strike of fracture rich zone determined the direction of fracturing fluid leak-off and pressure propagation. As the fracturing fluid tended to filtrate along long fractures, it was suggested to seal the natural fractures near hydraulic fractures before fracturing treatments. Moreover, fracturing fluid viscosity had certain influence on leak-off velocity.

Key words: fracturing fluid leak-off, fracture networks, clustered distribution, multiplicative cascade, permeability tensor

中图分类号:

TE357.1

游先勇,赵金洲,李勇明,许文俊. 考虑天然裂缝成簇分布的压裂液滤失研究[J]. 油气藏评价与开发, 2019, 9(2): 38-43.

You Xianyong,Zhao Jinzhou,Li Yongming,Xu Wenjun. An investigation into fracturing fluid leak-off considering the clustered distributed natural fractures[J]. Reservoir Evaluation and Development, 2019, 9(2): 38-43.

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