Abstract

K-Limestone is the limestone unit in the Jambi Area which is regionally equivalent to Baturaja Limestone in the South Sumatra Basin. Unlike the Baturaja limestones in the Palembang Sub-basin, which rest on the Talang Akar Formation, the K-Limestone in the Jambi sub-basin is intercalated with sediment of the Gumai Formation mainly in the depocenter and hinge zone areas. It also rests on pre-Tertiary rock on Basement highs.

The distinction between limestone development in the Jambi compared to the Palembang sub-basin is greater amount of growth faulting in the Jambi sub-basin. The K-Limestone probably developed at the end of a transgressive period as a condensed section, which separates the Gumai Formation into Upper Gumai and Lower Gumai intervals.

Seismic should show that the K-Limestone horizon has good seismic amplitude, good continuity, and extensive lateral development. Seismic mapping indicates that the K-Limestone was deposited in a relatively constant environment, independent of morphology. Drilling data show that in the depocentre area this limestone layer is thin, approximately 2 to 10 meters thick. Based on microscopic observation of samples from exploration wells, this limestone is rich in planktonic foraminiferas helping to confirm that the K-Limestone developed as a condensed section.

The K-Limestone that developed in the depocentre has different characteristics compared to basement high areas. K-Limestone in the depocentre area is characterized by thin layers and high density, whereas in basement high areas, the limestone is associated with reefal carbonates which often play a role as good reservoirs.