GAS-FLOW IN POROUS-MEDIA WITH KLINKENBERG EFFECTS

Gas flow in porous media differs from liquid flow because of the large gas compressibility and pressure-dependent effective permeability. Th e latter effect, named after Klinkenberg, may have significant impact on gas flow behavior, especially in low permeability media, but it has been ignored in most of the previous studies because of the mathemati cal difficulty in handling the additional nonlinear term in the gas fl ow governing equation. This paper presents a set of new analytical sol utions developed for analyzing steady-state and transient gas flow thr ough porous media including Klinkenberg effects. The analytical soluti ons are obtained using a new form of gas flow governing equation that incorporates the Klinkenberg effect. Additional analytical solutions f or one-, two- and three-dimensional gas flow in porous media could be readily derived by the following solution procedures in this paper. Fu rthermore, the validity of the conventional assumption used for linear izing the gas flow equation has been examined. A generally applicable procedure has been developed for accurate evaluation of the analytical solutions which use a linearized diffusivity for transient gas flow. As application examples, the new analytical solutions have been used t o verify numerical solutions, and to design new laboratory and field t esting techniques to determine the Klinkenberg parameters. The propose d laboratory analysis method is also used to analyze data from steady- state flow tests of three core plugs from The Geysers geothermal field . We show that this new approach and the traditional method of Klinken berg yield similar results of Klinkenberg constants for the laboratory tests; however, the new method allows one to analyze data from both t ransient and steady-state tests in various flow geometries.