Bulletin of the Geological Society of Malaysia, Volume 37, July 1995, pp. 191 – 204
PETRONAS Carigali Sdn. Bhd., Kuala Lumpur
Abstract: There are four (4) common reasons why drilling of a well is terminated, namely reservoirs are not economical in the deeper section, reservoirs are poorly developed, operational problems and overpressure.
Eighty percent of wells drilled in the Malay-Penyu Basin have been terminated either in anticipation or due to overpressure. This study uses pressure versus depth plots generated from RFT and DST readings taken in 94 exploratory well spread throughout the Malay-Penyu Basin.
Overpressure in this area is found to be neither depth dependent nor age related. The margins of the Malay Basin and the entire Penyu Basin are found to be normally pressured. The central portion of the Malay Basin is overpressured. The onset of overpressure appears to be abrupt in the north and more gradual in the southern portion.
Carigali drilled Resak 6F-18.4 in 1993 and successfully penetrated an overpressured zone finding hydrocarbon bearing reservoirs within and beneath this zone. An understanding of this phenomenon is crucial in the planning of safe and efficient drilling campaigns.