Study Of Bennett Field.

Chedid, Rachid

Honours Degree, 1988

South Australian Institute of Technology

Abstract

The Bennett Field is located in the block designated ATP 384/PL 17 in the south-east Surat Basin, Queensland covering an area of 110 square kilometres.

Eight wells (Bennett #1, Bennett #2, Bennett #3, Bennett #4, Leichhardt #1, Leichhardt #2, Lorraine #1 and Devon Park #1) and the seven available seismic lines (H3, H4, H7, H8, H15, 81E-11 and 81E-11E) are used to evaluate the potential of the block. Two wells, Bennett #1 and Bennett #4, have produced a total of 116,317 bbls of oil to May 1988 since 1966. Four formation tops are correlated using the seismic, the Permian Sequence (coals and siltstone), the Upper Precipice Sandstone, the Evergreen Formation (shales) and the Hutton Sandstone.

The two-way travel time maps of the formation tops show an anticline plunging to the south-west with a "closure" in the vicinity of the wells Bennett #l, Bennett #2 and Bennett #4. Folding-anticlinal growth during deposition is apparent by the isopach maps.

A fluvial model is proposed for the Bennett Field. The Upper Precipice Sandstone is the prospective formation; within this formation a sand called Unit X herein is correlated as the reservoir. A structural trap is postulated in the vicinity of the wells Bennett #l, Bennett #2 and Bennett #4, and a possible stratigraphic trap to the north-east of Bennett #4 due to a facies change forming a seal. The water saturation (Sw) was determined using the Simandeoux and the Indonesian equations giving an average of 36%. An average of 13 feet thickness for the net pay zone is interpreted. This reservoir is a solution gas driven reservoir. The reserves are estimated between the oil shale contact and the water oil contact to give recoverable reserves of 238,000 bbls and 524,000 bbls respectively. However there could be greater potential in this area in general due to a combination of structural and stratigraphic traps.