oa Prediction of Gas-Oil Contact from Surface Seismic Exploration

The fluid behavior in the reservoir of hydrocarbon resources greatly affects the oil production. Quantifying the amount and the distribution of hydrocarbon in the subsurface offers useful information to modify the future planning. The gas-oil contact (GOC) is expected as an indicator of oil observed by surface seismic exploration at low frequency. In this study, we attempt to grasp the movement of GOC in a simulation based on the Biot equations. The Biot equations consider the poroelastic media composed by solid and fluid phase, which allow us to handle the fluid alteration directly. We simulated with a second-order, finite-difference Biot scheme and investigated the effect of GOC and oil-water contact (OWC) under some assumptions in fluid alteration. The results show the possibility of surface seismic to be used to estimate the behavior of GOC in the subsurface. We also introduce the concept of active/inactive pores to derive the property of solid matrix phase from solid grains and including fluid, which had little influence on the wave data received.