Borehole gravimetry survey in Central Luconia carbonate reservoirs

Author : Mah Kok Gin and Frans Van Den Berg
Publication : Bulletin of the Geological Society of Malaysia
Page : 61-65
Volume Number : 36
Year : 1994

Bulletin of the Geological Society of Malaysia, Volume 36, Dec. 1994, pp. 61-65 

Borehole gravimetry survey in Central Luconia carbonate reservoirs


Sarawak Shell Berhad, Miri, Lutong, Sarawak


Abstract: A borehole gravimetry log (BHGM) was taken in four wells in 1992. The gravimetry tool is a wireline logging tool that records formation density far away from the wellbore. Density differences from large structures can be detected several hundreds of feet away from the borehole compared to a conventional density log which only measures the immediate surrounding of the wellbore, in the order of one foot. The objective of running BHGM in the wells was primarily to determine lateral continuity of the porosity of the gas-bearing carbonate reservoirs.

General performance of the tool was good. An accurate BHGM density profile was obtained for each well without major operational difficulty. The BHGM density showed an overall agreement with the conventional density log indicating a good lateral continuity of the reservoirs. Small scale differences between conventional density and BHGM density can be explained by local variations in porosity. In one of the wells, the BHGM confirmed that the very low porosity of 8% observed on the conventional density log in a tight layer is a localised feature.