Open Up a New Insight to Explore Bypassed Oil in Stratigraphic Flank Area Reservoir

Abstract

Recognizing and further improving such stratigraphic or combination trapping configurations are important not only for future exploration portfolio but also in mature fields development, where most of the structural traps have been drilled massively in the past years. Most explorer and subsurface practitioners think that stratigraphic or combination trap has higher risk than other traps, in fact that stratigraphic traps had a commercial success rate (CSR) of 32% globally in line with other trap types (Westwood Energy, 2020).

One of the field candidates which being executed in 2021 was SLD field that discovered in 1975 with a length of 3 kms north-south direction and 2 kms wide east-west direction. SLD field has various productive reservoir and interestingly developed with stratigraphic trap system in Sihapas Group, this anomaly observed from current oil attribute map and proven last workover result in the flank area. The reservoir target for 2021 drilling campaign was 394sd which located in flank area of SLD field. An integrated strategy has been successfully adopted in SLD field, producing with almost ~1000 BOPD gain during 2021 drilling campaign which notably come from 394sd by stratigraphically. From structural position, 394sd is located relatively down-dip in flank area while the reservoir quality change into poor quality in the up-dip position and behave as barrier or stratigraphic trap. Heterogeneity of facies changes in SLD field impacts to the occurrence of stratigraphic trap that proved by the production attribute map from current active and last production of SLD field which positioned in flank area. One of the engineering approaches to effectively producing current oil in SLD field is narrowing well spacing and resulting a good oil production, compared back in 2010 with ~400 meters of spacing. This paper will tell in how we develop well candidacy with stratigraphic uncertainty and gained ~1000 BOPD to arrest production decline of this field.