Hydrocarbon migration and accumulation model of fractured-vuggy reservoir under unconformity surface: A case study of carbonate reservoir in Tarim Basin

It is difficult to accurately evaluate petroleum resources or reserves in the fractured-vuggy carbonate rocks under unconformity surface using traditional volumetric method. This paper proposes a three-dimensional invasion percolation model (3D-IP) to simulate hydrocarbon migration and accumulation in fractured-vuggy carbonate rocks, based on three-dimensional geologic modeling, structure, porosity and the quantity of supplied hydrocarbon data. The model has 3 main points: (1) Trace migration paths along the direction with least resistance; (2) When an obstacle is encountered, oil and gas flow back; (3) When the balance between driving force and resistance is broken, oil and gas continue to migrate by finding the weakest points and paths. The model can make up for the inadequacy of the volumetric method. It can predict not only the amount of petroleum resources, but also their locations. By stochastic model experiment and practical application of Block S6 in Tazhong area of the Tarim Basin, this paper confirms the validity and superiority of the proposed model, and points out potential targets in Block S6, thus giving exploration direction of fractured-vuggy reservoir in the slope area.