Publications

Time-lapse microgravity method is the method of gravity (x,y,z) development by adding the 4th dimension of time(t). The principle of this method is to repeat gravity measurement either daily, weekly, monthly or yearly by using a gravimeter which has an accuracy in the order of micro-Gall. In this study the time-lapse microgravity method is used to monitor fluids movement, water saturation changes, pressure changes, and density changes in a reservoir due to the Enchanced Oil Recovery (EOR). EOR is the process of injecting water into reservoirs to drain the remnants of oil in the pores of the reservoir rock. By using primary data, literature review, and case studies on the Field"TFQ", Sumatra, we obtained the results of changes in values of time-lapse microgravity anomalies measured in January, May, and September, 2003 due to water injection and prodution processes. After the injection process in the reservoir, the formation density increased by 0.065 gr/cm3, the reservoir pressure decreased by 100-450 psi, and water saturation increased by 15-45% with an effective porosity of 15% from January until September. In the reservoir of Field "TFQ", fluids move from northeast to southwest and then toward the southeast direction due to two major faults (sealing faults) that trend northeast-southwest. So the conclusion that can be derived from this research is that the time-lapse microgravity method can help to monitor the activities of EOR in the reservoir of Field “TFQ” with the parameters of density changes, water saturation changes, pressure changes, and fluid flow direction in the reservoir.