APPRAISAL OF A COMPLEX, PLATFORM CARBONATE, BUKIT TUA DISCOVERY, KETAPANG PSC, EAST JAVA BASIN, INDONESIA

摘要

The Bukit Tua-1 well, drilled in 2001, discovered oil and gas in what is expected to be a very complex, platform carbonate setting. The well was drilled to approximately 6,500 ft with the primary reservoir being a 300 ft gross section of early Oligocene carbonates of the Ngimbang Formation, overlying basement. Well deliverability was proven to be good, with flow rates of 2,800 - 4,500 bopd recorded from DST's. Rock data are limited with no conventional core and sidewall cores only obtained from the closest offset well, Jenggolo-1, 19 kms. to the west. Hence, many uncertainties remain regarding rock properties, in particular distribution of facies and porosity.rnTrap definition is problematic because of strong lateral velocity variations in the overlying Wonocolo Formation caused by lithological contrasts between large carbonate banks and inter-bank areas. To try and resolve a number of issues, including trap definition and facies distribution, a 3D seismic survey was acquired and processed during 2002. This dataset forms the basis of an integrated reservoir study using seismic attributes, including facies maps, stratal slicing, and relative impedance data, together with facies analysis from the limited well data, to develop a geological model for the area. A velocity cube, which attempts to remove the overburden effects, has allowed the trap model to be better defined. All data were used to optimally locate 2 appraisal wells drilled in 2003.