Abstract：The gas permeability of porous medium can be estimated by in-situ tests, which can avoid the defects of laboratory tests, that is, the pore structure of samples must be steady, and the sample size is small. The equation used in-situ tests is derived from 1-dimensional radial gas seepage model, and then the pressure field is given based on analysis of 2-dimensional axially symmetric model. The radial outer boundary rout in the in-situ test equation is the sum of test length and half packer length, and the effective region is the sphere of which the radius is rout. The judgment of whether or not the tests obey the Darcy's law is deduced: the tests are conducted under at least three different fluxes. Taking the flux as abscissa and the difference of pressure square as ordinate, the test points can be curve-fitted as a straight line which crosses origin.
牛冠毅, 曹渊, 王铁良. 原位气体渗透率测量试验公式推导及分析[J]. 岩土工程学报, 2015, 37(9): 1705-1709.
NIU Guan-yi, CAO Yuan, WANG Tie-liang. Deduction of in-situ gas permeability test equation. Chinese J. Geot. Eng., 2015, 37(9): 1705-1709.
[1] 陈卫忠, 杨建平, 伍国军, 等. 低渗透介质渗透性试验研究[J]. 岩石力学与工程学报, 2008, 27(2): 236-243. (CHEN Wei-zhong, YANG Jian-ping, WU Guo-jun, et al. Experimental study on permeability in low permeability media[J]. Chinese Journal of Rock Mechanics and Engineering, 2008, 27(2): 236-243. (in Chinese)) [2] LECAIN G D. Pneumatic testing in 45-degree-inclined boreholes in ash-flow Tuff Nuar Superior, Arizona[R]. Virginia: Geological Survey Water-Resources Investigations, 1995: 95-4073. [3] LECAIN G D. Air-injection testing in vertical boreholes in welded and nonwelded tuff, Yucca Mountain, Nevada[R]. Virginia: Geological Survey Water-Resources Investigations, 1996: 96-4262. [4] COOK P. In situ pneumatic testing at Yucca Mountain[J]. International Journal of Rock Mechanics and Mining Sciences, 2000, 7: 57-67. [5] HVORSLEV M J. Time lag and soil permeability in ground-water observations[R]. Washington D C: U.S Army Corps of Engineers Bulletin, 1951. [6] 李传亮. 储层岩石连续性特征尺度研究[J]. 中国海上油气, 2004, 16(1): 63-65. (LI Chuan-liang. A study on characteristic scale of reservoir rock continuity[J]. China Offshore Oil and Gas, 2004, 16(1): 63-65. (in Chinese))
