Abstract

Exploration well MSBG-1 was drilled in 1986 as the first onshore well to test the low relief structural play in the Malacca Strait PSC. The primary objective of the well was the Early Miocene Lower Sihapas fluviodeltaic sands proven to be productive not only in the Malacca Strait PSC but elsewhere in the Central Sumatra Basin. A total of four consecutive conventional cores were cut. The available whole core data includes a complete single parasequence exhibiting a progradational cycle some 110ft thick from delta front through tidal flat to distributary channel deposits capped by channel abandonment facies.

The core wireline logs indicate that the Lower Sihapas sediments were deposited in a tidally dominated delta environment which, due to relative sea level changes, resulted in the repeated stacking of reservoir units. It is unclear whether the relative sea level changes were due to lobe switching, tectonism or eustacy.

The stratigraphy of the Lower Sihapas Formation has directly contributed to the reserve size of the Kurau Field whereby stacking of reservoir and seal couplets has enabled the stacking of numerous oil pools within a single anticlinal structure. Exploration well MSBG-1 tested oil at a cumulative rate of 8447 BOPD from five intervals and proved to be the discovery well of the Kurau Field which is now estimated to contain in excess of 150 million barrels of oil in place.