The Complexity of Basement Characterization from Ketaling Complex as a Revival of Gas Potential in West Ketaling Structure, Jambi Sub-Basin, South Sumatra Basin

Abstrak

Ketaling Field is located 32 Km respectively south East and west-South West of Jambi. Ketaling area was a mature oil field whereas the Bulian complex area is toward the process for gas field development. Ketaling Structure has been acquired by sparse 2D seismic grid since 1978 to 1982. Pertamina continue to acquire 3D seismic 2003 Ketaling, in favor for field development.

Ketaling area are sitting in Jambi Sub-basin, which is located in NW nose of South Sumatra Basin. The basin divided into several blocks that controlled by basement high and low. Ketaling field is the example of the unique paleo-high setting in Jambi sub-basin divided into two physiographic units, mainly controlled by large normal strike slip fault.

The purpose of this study is to investigate the character, geometry and potential of the Basement zone which has found in well of KBS-X1 & KTB-X2 from structural analysis, biostratigraphy analysis, Production data test analysis and combined with our integrated analysis from 3D seismic data interpretation and electric-logs. From the result, there are several interesting findings, namely the Basement Rock found in the West Ketaling structure, which is a metamorphic type of phyllite rock, further evidenced by the mudlog data on KBS-X1 and new Exploration well in West Ketaling Structure namely TJA-X1.

Furthermore, it is stated that the data from the well test in KBS-X1 has a 3.5mmscfd QGas result with a 32/64 inch choke; despite the result in KTB-X2 well generated poor result; Qgas 0.003 mmscfd eventhough it is in the same zone. The main factor to this contrasting data is the intensity of the presence of faults and fractures in the basement are highly instrumental in determining the fractured basement distribution which correlated align both with porosity and the production rate of the formation itself.  From this study, the basement model is capable to determine the expansion and character of basement which is crucial for future development opportunities.