Success of Structural Stratigraphic Combination Trap, Arthit Field, Gulf of Thailand

Abstract

The Arthit gas field is located in the northwest of the North Malay Basin, offshore Thailand. The hydrocarbon accumulation is mostly discovered in Miocene to Oligocene reservoir. The subsurface geology shows the existences of structurally complex, as highly faulted seen over the entire Arthit concession. The field was started on production since 2008. Most of the gas production is primarily produced in stacked channel reservoir in structural trap e.g. 3-way dip closure and 4-way dip closure. However, to prolong the field life by upsurge gas production, developing hydrocarbon production only from structural trap might not effectively sufficient. Therefore, in recent years, the structural stratigraphic combination trap such as Nose structure is becoming more interested. In the past, Nose structure was rarely considered to be drilling target for development wells. Apparently, in Arthit Field, Nose structure is believed that it contains higher risk in term of trap and seal compared with other trap styles. Furthermore, seismic reservoir characterization and hydrocarbon indication of stacked channel reservoirs are unfeasible due to the properties. Moreover, the combination of the complexity of trap style and the complication of reservoir indication has increasingly more complicated to develop hydrocarbon in Nose structure. In 2012, an appraisal well was drilled to appraise hydrocarbon in nose structure (structural stratigraphic combination trap). Additionally, another objective was to prove the geological model assumption of reservoir distribution and direction. The result of this well has been represented by the success of proven 88 mTV net pay in stacked channel reservoir. As a result, in 2013, the production platform with fifteen development wells, which were targeted in gas accumulation, was successfully drilled. All of the wells were revealed by the proven gas, good reservoir properties, with the maximum 90mTV of gas sand. By this rewarding, it has been clearly proved that the geological model assumption is applicable for Nose structure in Arthit Field. Five wells were subsequently perforated with the initial rate of 15.7 MMscfd. Currently, the production from only these five wells becomes 25.0 MMscfd, represented about 10% of field daily production rate. This favorable outcome is inspiring and encouraging to get more interest in Nose structure in Arthit Field.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015