Low Resistivity Reservoir in Talang Akar Formation : Reservoir Characterization and Production Enhancement
Keywords:
low resistivity, Stimulation, reservoir characterization, production enhancementAbstract
The reservoir with low resistivity value was initially considered unattractive because of high Sw value, but eventually provided
satisfying production. This paper will present the reservoir characterization of low resistivity reservoir and the success of the oil and gas production enhancement in Talang Akar Formation, especially in TLJB Field in South Sumatera.
The typical oil resistivity from the Talang Akar Formation in South Sumatera is mostlikely >10 ohm.m. But, in TLJB Field, lately known that the typical resistivity cut-off for oil is only >3 ohm.m and gas is only >7 ohm.m. Mudlog with gas chrome up to C5 and trace oil shows do not always indicate oil reservoir, in fact, most of them indicate gas condensate reservoir. Reservoir characteristics was evaluated by combining cutting data, mudlog, core analysis, open hole logging, wireline formation testing and well testing. The most reliable data in determining reservoir fluid is wireline formation tester, by evaluating gradient of reservoir pressure and fluid scanning. Cutting and core analysis was carried out to find out clay mineralogy, type of sedimentology, and value of Swc. Re-evaluation of petrophysics was performed, because of standard petrophysical analysis gives over-estimated Sw, eventhough the water cut is very low when produced. Pressure transient analysis identify that most of the reservoir have a high skin value, then stimulation is needed. Solubility test of cutting indicate that HCl-HF is the most appropriate type of acid. For gas reservoirs, acidizing with HCl-HF gives very satisfying results. However, for oil reservoirs, acidizing does not have a significant effect, then fracturing is a suitable method for oil reservoirs.
By understanding the characteristics of the low resistivity reservoir and the proper stimulation method, it is expected to unlock the opportunities for discovering the hydrocarbon potential and increase the production.
