Slug Testing in Wells with Finite Thickness Skin

Abstract

We present an analysis of the slug test in a well surrounded by an annulus of altered material, which is treated as a skin of finite thickness. By assuming the skin has a thickness, the storage capacity of the altered material is included in the analysis. The problem is solved in the Laplace domain. The solution is found in terms of well-bore storage and the thickness, hydraulic conductivity, and specific storage of the skin. Type curves are generated by numerical inversion of the Laplace transform solution. Ye find that standard methods of analysis, involving a skin of infinitesimal thickness, are adequate for open-well or drill-stem tests. However, for pressurized tests the response may differ markedly from standard slug-test solutions.