So Similar and yet so Different: Comparing and Contrasting the Controlling Factors for Reservoir Development of Two Southeast-Asian Tertiary Carbonate Build-Up Gas Fields: Malampaya and Luconia Fields

Georg Warrlich¹, Wenche Asyee², Phil Cassidy¹, Maria Boya², and Jan-Henk Van Konijnenburg^3
1 Shell International, Rijswijk-ZH, Netherlands
² Shell Carbonate Team,
³ Sarawak Shell Bhd,

Multidisciplinary subsurface studies were carried out on Malampaya and one Luconia isolated build-up gas reservoir by the Shell Carbonate Development Team over the past 3 years. The approach taken was to understand the present day reservoir properties based on the processes of their formation to be able to predict away from data points guided by geological principles.

Both build ups have similar ages, faunal assemblages, dimensions, and comprise both aggradational zones preceding final drowning that overlie low porosity zones which separate them from earlier carbonates. However, in Malampaya the aggradational phase overlies a tectonically deformed older build up phase whereas in the Luconia platform it sits on a wider platform. The Luconia low porosity zone formed by deposition of fine carbonates of deeper water origin, whereas the Malampaya zone formed by exposure and cementation. Significant post and syn-tectonic deformation is only recognized in Malampaya.

Not surprisingly, secondary porosity formation by early and late diagenetic processes was important in both reservoirs, however driven by dolomitisation in the Luconia platform and mainly by exposure related leaching in Malampaya. These differences of so similar appearing platforms have important consequences for the reservoirs and their development.

The authors would like to thank PETRONAS, PNOC and ChevronTexaco for their support.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005