Method for determining hydrocarbon accumulation threshold of hydrocarbon containing basin fragmentary rock

Abstract

The invention discloses a method for determining a hydrocarbon accumulation threshold of hydrocarbon containing basin fragmentary rock. The method comprises the following steps: (1), establishing a change model about how sandstone and mudstone change with embedded depth in a research zone; (2), establishing a relation model of sandstone and mudstone permeability and porosity; (3), establishing a relation model of sandstone and mudstone hole radii, the porosity and the permeability, and calculating the hole radius values of sandstone and mudstone in different depth; (4), calculating a ratio of mudstone interface potential energy to sandstone interface potential energy, establishing a change model about how the ratio changes with the embedded depth, and determining a maximum boundary and a minimum boundary when the ratio of the mudstone interface potential energy to the sandstone interface potential energy is distributed along with the embedded depth; (5), calculating ratios of the mudstone interface potential energy to the sandstone interface potential energy about a hydrocarbon layer and a dry layer in the research zone, and subjecting the ratios of the mudstone interface potential energy to the sandstone interface potential energy about the hydrocarbon layer and the dry layer in the research zone to the change model established in step (4); (6), dividing a borderline about how the potential energy of the opposite interfaces of the hydrocarbon layer and the dry layer is distributed along with the embedded depth; and (7), sandstone porosity corresponding to an intersection point between the borderline and the maximum boundary of the ratio of the mudstone interface potential energy to the sandstone interface potential energy being reservoir layer critical porosity corresponding to the hydrocarbon accumulation threshold of the research zone.

Description

technical field [0001] The invention relates to a method for determining the bottom limit of oil and gas accumulation in clastic rocks in oil-gas-bearing basins. Background technique [0002] With the improvement of exploration and development technology, the research focus of oil and gas resources at home and abroad has gradually shifted from shallow layers to deep layers, and from conventional oil and gas reservoirs to unconventional oil and gas resources. The bottom limit of oil and gas accumulation involved in the present invention is the critical porosity of the reservoir corresponding to the maximum burial depth where oil and gas accumulation can occur. When the reservoir porosity is less than the critical porosity, oil and gas accumulation cannot occur. [0003] Scholars at home and abroad have done some research on the critical porosity of reservoirs. The critical porosity of reservoirs obtained varies greatly due to different research methods and research degrees. ...

AI Technical Summary

Problems solved by technology

The critical porosity value determined by this method is lower than that of the above eight methods, and is closer to the critical porosity of the reservoir corresponding to the bottom limit of oil and gas accumulation. Many parameters are used to jointly determine the critical porosity value, but each parameter is different. Only qualitative analysis was carried out, and no clear parameter standard for judging the critical porosity was given, which made the method have many inaccuracies in the application process

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