Modeling the effect of clay drapes on pumping test response in a cross-bedded aquifer using multiple-point geostatistics

JOURNAL OF HYDROLOGY

卷:450

Article

Huysmans, Marijke¹  Dassargues, Alain^1,2 

[1] Katholieke Univ Leuven, Dept Earth & Environm Sci, B-3001 Heverlee, Belgium

[2] Univ Liege, Dept Architecture Geol Environm & Civil Engn ArGE, B-4000 Liege, Belgium

关键词: Multiple-point geostatistics;    Groundwater flow;    Heterogeneity;    Pumping test;    Upscaling;    Cross-bedding;   

DOI  :  10.1016/j.jhydrol.2012.05.014

来源: Elsevier

【 摘 要 】

This study investigates whether fine-scale clay drapes can cause an anisotropic pumping test response at a much larger scale. A pumping test was performed in a sandbar deposit consisting of cross-bedded units composed of materials with different grain sizes and hydraulic conductivities. The measured drawdown values in the different observation wells reveal an anisotropic or elliptically-shaped pumping cone. The major axis of the pumping ellipse is parallel with the strike of cm to m-scale clay drapes that are observed in several outcrops. To determine (1) whether this large-scale anisotropy can be the result of fine-scale clay drapes and (2) whether application of multiple-point geostatistics can improve interpretation of pumping tests, this pumping test is analyzed with a local 3D groundwater model in which fine-scale sedimentary heterogeneity is modelled using multiple-point geostatistics. To reduce CPU and RAM demand of the multiple-point geostatistical simulation step, edge properties indicating the presence of irregularly-shaped surfaces are directly simulated. Results show that the anisotropic pumping cone can be attributed to the presence of the clay drapes. Incorporating fine-scale clay drapes results in a better fit between observed and calculated drawdowns. These results thus show that fine-scale clay drapes can cause an anisotropic pumping test response at a much larger scale and that the combined approach of multiple-point geostatistics and cell edge properties is an efficient method for integrating fine-scale features in larger scale models. (c) 2012 Elsevier B.V. All rights reserved.

【 授权许可】

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