Chasing New Deep Play in South Malay Basin

Abstract

Abstract Malay Basin is a relatively matured basin which has undergone exploration and production for more than three decades, mainly from stratigraphic units of Miocene to Late Oligocene. The matured nature of the basin has driven PETRONAS to evaluate the remaining deep play potentials. DD is a deep prospect below D Field. Several pre-drill risks were identified during prospect maturation namely, high temperature (450F), high pressure (11000 psi) and poor reservoir quality with low porosity (6% to 12%) and low permeability of <1 mD. PCSB however decided to drill DD-1 due to its large four way dip closure (approximately 250 km2), volume in-place and potential to open up other deep plays. DD-1 is PETRONAS' first Ultra High Pressure High Temperature (HPHT) well, located in southern Malay Basin to evaluate gas in Group M (Early Oligocene age). It penetrated Group M in D Field and reached its final TD at 4350 m TVDSS. It recorded temperature and pressure of 488oF and 13900 psi respectively. DD-1 proved that the petroleum system is working for the deep play by intersecting several gas bearing sandstone units namely M20, M30, M60 and M70 (C1-nC5, total gas 5% to 13%). Reservoir effectiveness is the major issue - low porosities (3% to 8%) and extremely low permeability (0.0025mD). Well testing over M20 flowed gas to surface and was flared, however the testing was deemed inconclusive. The HPHT nature of the well also presented operational challenges such as drilling within narrow mud weight and fracture gradient margin and the availability of suitable HPHT logging tools. Well results indicated that Group M was gas bearing; however at this stage is not commercially recoverable. The deep play potential remains to be commercially exploited but better understanding of natural fracture networks and the utilising of advanced technology will be required. 1.0 Introduction DD-1 well is located approximately 236 kilometers northeast of Kemaman Supply Base (KSB), in water depth of 75 meters offshore Peninsular Malaysia (Figure 1). The prospect basically lies below the existing D Field which is currently being produced from the shallower Group I, J, K and L reservoirs. The primary objective of the proposed DD-1 is to evaluate the hydrocarbon potential of the Group M sandstones which are within a structural four-way dip closure, the first ever well to test Group M in D Field. DD-1 is PETRONAS' first Ultra High Pressure High Temperature (HPHT) well; it was spudded on 01 March 2013 and after five months of drilling campaign, it successfully reached final TD at 4388 m MDDF on 18 July 2013. It experienced high temperature and high pressure of 488oF and 13900 psi at final TD.