基于分形理论的粗糙裂缝钻井液漏失模型研究

发布时间：2018-06-02 22:18

本文选题：裂缝性地层 + 粗糙度　；参考：《石油钻探技术》2017年04期

【摘要】：当前的漏失模型均未充分考虑裂缝粗糙度对钻井液漏失的影响,对粗糙裂缝的漏失规律认识不清,反演得到的裂缝宽度误差大。为此,基于分形理论建立了二维粗糙裂缝模型,采用赫-巴模式描述了钻井液的非牛顿流变特性,采用指数方程描述了裂缝的非线性变形特征,建立了钻井液漏失模型,并采用中心差分方法对方程进行了数值求解,分析了网格尺寸、分形维数及标准差对钻井液漏失速率及累计漏失量的影响。研究结果表明,模拟网格尺寸足够大时,数值模拟结果的可靠度较高;随着标准差增大,微凸体数量增加、起伏程度提高,漏失速率及累计漏失量显著减小;分形维数对漏失的影响与裂缝面是否接触紧密相关,没有接触时影响较小,接触后随着接触面积增大影响增大。研究表明,建立的漏失模型可为认识漏失机理和反演裂缝宽度提供理论参考。
[Abstract]:The current leakage model does not fully consider the effect of the crack roughness on the leakage of the drilling fluid. It is not clear about the leakage law of the rough cracks, and the error of the crack width is large. Therefore, a two-dimensional rough crack model is established based on the fractal theory. The non Newtonian rheological properties of the drilling fluid are described by the Hertz model, and the exponential square is used. This paper describes the nonlinear deformation characteristics of the cracks, establishes the drilling fluid leakage model, and uses the central difference method to numerically solve the equation. The influence of grid size, fractal dimension and standard deviation on the leakage loss rate and cumulative leakage of drilling fluid is analyzed. The results show that the numerical simulation results are large enough for the simulated grid size. With the increase of the standard deviation, the number of micro convex body increases, the fluctuation degree increases, the leakage rate and the cumulative leakage decrease significantly; the effect of fractal dimension on the leakage is closely related to the contact of the fracture surface, and the contact area increases with the contact area when the contact is not touched. The model can provide theoretical reference for understanding leakage mechanism and retrieving crack width.
【作者单位】：中国石化石油工程技术研究院;页岩油气富集机理与有效开发国家重点实验室;油气藏地质及开发工程国家重点实验室(西南石油大学);
【基金】：国家科技重大专项“海相碳酸盐岩超深油气井关键工程技术”(编号:2017ZX05005-005) 国家自然科学基金项目“页岩油气高效开发基础理论研究”(编号:51490650)联合资助
【分类号】：TE28

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