The characteristics of petroleum seepage in coal seams: a case study of Ordos Basin

To solve the technical problems of safe and efficient exploitation of coal resources by abandoned oil wells in the Ordos Basin, several characteristics of the coal seam need to be fully explored: petroleum seepage pressure, seepage velocity and seepage range. However, these are difficult to determine in situ, and often numerical models are used. A comprehensive analysis method combining COMSOL Multiphysics numerical software and seepage model is proposed here based on the continuous non-linear theory of seepage flow and the constructed seepage channel model of different pores and fissure coal samples. The characteristic parameters are determined by on-site measurement to verify the accuracy of the proposed analysis method. The results show that the characteristic parameters of each seepage flow studied differ from those measured in the field; however, the difference is small. The seepage pressure in time and space can more accurately describe the changes in the tensile parameters. The spatial dimension seepage pressures forms three-stage distribution along the radial direction. The maximum seepage velocity is about 16 m/month, and the radial seepage range is 221 similar to 235 m. The comprehensive analysis method based on the new seepage model quantitatively reflects the changes in seepage characteristic parameters and enhances the methods of seepage research.