Multiscale core-seismic analysis for karst characterisation of MX field, Central Luconia Province, Offshore Sarawak, Malaysia.

In the Oil and Gas industry, carbonate reservoirs play an important role in holding most of the world’s hydrocarbon reserves. They account for 60% of the world’s oil and 40% of the world’s gas reserves. Nonetheless, carbonate reservoirs continue to pose challenges due to their multi-scale heterogeneities from depositional and post-depositional physical and chemical diagenetic processes that alter the rock’s structure, affecting its porosity and permeability. The Middle Miocene Central Luconia province located in offshore Sarawak has received much attention since its discovery by Shell as one of Malaysia’s largest gas fields in 1971. Over 250 carbonate build-ups occur offshore in the Central Luconia province. Around 60 platforms have been drilled and almost every field has encountered indications for high permeability zones likely associated with karst such as mud losses and drill bit drops during drilling activities. Some fields were left abandoned due to the mud losses that could not be controlled. Geometries, distribution, and the dimension of karst in Central Luconia fields remain unknown. They have not been studied in detail. Due to the current lack of understanding of karst morphology, a regional integrated study has been initiated in this research to establish a systematic multidisciplinary approach and acquire detailed geological understanding from one-dimensional to three-dimensional aspects. The heterogeneity of carbonate reservoirs arises from the differences of porosity/permeability, which are marked, by diagenetic overprint and/or meteoric dissolution resulting in Reservoir Rock Types (RRTs) with different petrophysical properties (Jimenez et al., 2020).