Quantitative characterization of hydrocarbon charging driving force and resistance during reservoir-forming stages: a case from the Maxi subsag, Raoyang sag

Abstract

Oil and gas migration and accumulation are different manifestations of driving force and resistance during the evolution process of oil-gas pool formation; thus, determining the relationship between the driving force and resistance during oil-gas pool formation is of great significance in exploring for oil and gas in subsags. Taking the Maxi subsag in the Raoyang sag as the study object and simulating surplus paleopressure evolution and quantitatively characterizing the lower limits of displacement pressure of the effective reservoirs, the evolution process of driving force and resistance of hydrocarbon charging during various stages was reproduced, and the relationship between the driving force and resistance of hydrocarbon charging in the subsag was determined. The paleopressure evolution of the subsag underwent three stages: initial accumulation—release—reaccumulation. The lower limit of the effective reservoir displacement pressure gradually increased as the physical properties of reservoirs worsened. The hydrocarbon driving in the subsag can be divided into three types: overpressure driving, buoyancy driving and hybrid driving. The subsag region had two periods of oil-gas pool formation with the different overpressure driving range and hybrid driving range.

Keywords:

• Hydrocarbon charging driving force
• hydrocarbon charging resistance
• surplus pressure
• displacement pressure
• hydrocarbon migration