Feasibility Study of “Full Tensor Gravity (FTG)” Approach to Detect Fluids Replacement Due to Oil Production

Feasibility study has been done to evaluate effectiveness of “Full Tensor Gravity (FTG)” approach to detect replacement of fluids due to oil production using a simplified geological model. Sensitivity analysis is applied through combination of forward gravity simulation and structural inversion on the assumption that the result of such forward simulation corresponds to pseudo field data. Although the reservoir is located at depth of 2,450 m in the target area, almost complete inverted result can be obtained using all the components of FTG in case of noise free. There is a possibility that practical imaging can be done using vertical gravity gradient alone. Nevertheless, since signal of gravity gradient due to fluid replacement is significantly low with level from 0.02 to 0.3 Eötvös. It follows that FTG approach to such deep reservoir should be applied through such as hybrid survey combined with “Micro-gravity survey”, by which detailed measurement can be done with order of several micro-Gals.