Study on the characteristics of organic-rich shale in the north area of Dongying depression

Abstract

In recent years, shale oil shows have been found in Shahejie Formation in the northern part of Dongying depression. To investigate the characteristics of shale oil in the northern part of Dongying depression, we have carried out a comparative study on the reservoir, oil bearing, and compressibility of shale in the northern steep-slope zone of Dongying depression and shale in the center of depression based on the mineral composition, reservoir physical properties, and pyrolysis experiments of drilling cores. The results find that the steep-slope zone shale and the depression central shale have good shale oil development potential. Three kinds of lithofacies developed in the steep slope and four kinds of lithofacies developed in the sag center. Interbedded sandstone with different thickness widely developed in the steep slope of Dongying depression. The development of micro-meso pores in the shale matrix and cement of interparticle pores of sandstone made shale in the sag center higher porosity than that of shale in the steep slope. However, macropores of interbedded sandstone significantly improved the permeability of shale series in the steep slope. Shale oil in the steep slope has higher gas/oil ratio, better mobility, and higher free-hydrocarbon content than the shale oil in the sag center. We predicted that the shale in the steep-slope zone has better shale oil production than the shale in sag center combined the fracturing capacity analysis.