Re-evaluation of hydrocarbon generation potential of the Upper Paleozoic coal-measure source rocks in the Hangjinqi area of Ordos Basin

The Upper Paleozoic strata in the Hangjinqi area of the Ordos Basin are an important field to increase reserves and productions for the North China Oil and Gas Branch, SINOPEC. It is necessary to conduct a re-evaluation of hydrocarbon generation potential for the Upper Paleozoic coal-measure source rocks in time, which is favorable to provide theoretical support for further exploration and deployment. The organic geochemical and organic petrological approaches were carried out in this study and integrated with the physical simulation of hydrocarbon generation and expulsion from formation pore by thermal compression, numerical simulation of TSM basin resource evaluation and new exploration data, in order to systematically analyze and compare the sedimentary environment, quality and distribution of the Upper Paleozoic source rocks, and further to conduct the re-evaluation of hydrocarbon potential. The results indicated that the Upper Paleozoic source rocks of the south of the fault belts in the Hangjinqi area appeared to have characteristics of good quality, high evolution degree, and a great thickness, whereas those in the north part of the fault belts displayed the negative characteristics. As indicated by the physical and numerical simulation results, the Upper Paleozoic coal-measure source rocks in the Hangjinqi area displayed a total gas generation amount of 15.922×1012 m3. The gas generation intensity to the north of the fault belts was less than 1×109 m3/km2, whereas that to the south ranged (1.5-3.5)×109 m3/km2, which has provided a material basis for the generation of large and medium gas fields.