HYDROCARBON RESERVOIR MONITORING USING GRAVITY 4D METHOD, IN “X” FIELD IN SOUTHERN SUMATRA AREA.

M.Irfan Mashudi, Adi Susilo, Ph.D

Geophysics Laboratory – Physics Department, Brawijaya University Malang

Veteran Street, Malang – East Java – Indonesia 65145

ABSTRACT

This monitoring of Microgravity 4D research using Gravitymeter Lacoste Romberg type G1158 with Alliod System, Gravitymeter Lacoste Romberg type G504 with feedback factor system. Gravitymeter Scientrex type CG3 with accuracy 1 Micro Gall. To make a map of gravity anomaly, use Surfer 8.0 version. Microgravity 4D research area divide into three block, with 1,5 Km x 1,5 Km of each block, total grid space was had amount 1500 point. The acquisition of the data has held as three periods; it’s on January, May, and September, 2003. Gravitational anomaly monitoring involves; surface groundwater, changeable reservoir mass, and subsidence. Average value of anomaly show that on January - May = -0,1842 and September – May = 0,1803. Average value of total monitoring which is January – September show that the gravitational anomaly value has decrease until -0,0183. The result of quantitative and qualitative interpretation show that microgravity 4D anomaly and its contrast density in oil field can give some information of subsurface structure and performance of reservoir caused of oil production, secondary gas cap, ground water, and water injection in production and injection well.