ABSTRACT
Since 1985 Bass Strait oil production has declined by over 100 kSTB/D (16 ML/d) to an average of 364 kSTB/D (58 ML/d) in 1988. To mitigate this decline Esso Australia has undertaken a coordinated program aimed at realising the full production potential of existing reserves and facilities. This program centres on three fronts; major projects such as gas lift and waterhandling, a workover program and the removal of facility constraints. Over the next 4 years this rate enhancement activity is currently forecast to offset declining production rates by an average of 60 kSTB/D (10 ML/d).
Currently over 60% of available oil wells are capable of being gas lifted, including two wells with average angles in excess of 70°, and it is planned to increase this number to over 75% in the near term. The strong water drive characteristics of Bass Strait reservoirs has resulted in increased formation water production. Waterhandling facilities have been installed to maximise production levels. Current waterhandling capacity is around 300 kSTB/D (48 ML/d) with half being achieved through use of hydrocyclones which provide improved portability and operating flexibility compared with conventional waterhandling equipment.
Since mid 1987 an average of over 4 workovers per month have been completed in an intensive program to achieve the full potential from all wells. This has been achieved through the use of alternative options to the conventional tubing pull workovers of the past. Extensive use has been made of coil tubing units (CTU), concentric rigs and a jack-up rig instead of conventional platform rigs, thus reducing costs and returning wells to production faster.
Platform facilities have been optimised through close liaison between operations and engineering personnel to locate and remove production constraints where possible. Integration of facilities for new developments has allowed production from existing reservoirs to be increased.
