Multi-Scale Spatial Simulation of Rock Pores by Geostatistics with a Scaling Law
Rock pores distribution is important because it influences capability of reservoirs for petroleum, groundwater, and geothermal fluids. In most cases, pore observations are carried out using rock samples of small size. However, reservoir characterization requires pore/particle distributions over wide area. This paper presents a geostatistical method to simulate pore/particle distributions at different scales by approximating pores/particles simply by spheres so that their sizes are determined only by radii. At different scales of the sample slice, statistical characteristics including maximum radius, and semivariogram parameters (sill and range) of pores/particles are obtained and then, relations between scales and these statistical parameters are quantified. Using these relations, the initial distribution model of pore/particle radii at a certain scale is generated randomly following the conditional cumulative distribution function for the sample. In order to modify the initial pore/panicle model, a simulated annealing method is employed to adjust the experimental semivariogram to the defined semivariogram model. Based on the final model, contacted pores/particles are connected and hydraulic properties are identified. As a case study, 4.6 mm × 2.5 mm slice of a Berea sandstone sample is used and the relations of the maximum radii with the semivariogram parameters (sill and range) and scales are identified at different scales. This scaling law is used to extend calculation areas of 5, 10, 15, 20, and 25 mm and pore/particle distributions at all scales are simulated. It was clarified from the results that the connectivity of pores increases largely with the size although the porosity is fixed over different scales. The trend is similar to the scale effect on hydraulic conductivity.
Chunxue Liu Katsuaki Koike
Graduate School of Science and Technology, Kwnamoto University, Kurokami 2-39-1, Kumamoto, Japan;Sch Department of Life and Environmental Sciences, Graduate School of Science & Technology, Kumamoto Uni
国际会议
The 12th Conference of the International Association for Mathematical Geology(第12届国际数学地质大会)
北京
英文
569-572
2007-08-26（万方平台首次上网日期，不代表论文的发表时间）