A Comprehensive Approach in Managing Uncertainties: Aryani AC-5 Basal Sand Case Study

Abstract

Asri Basin is one of the prolific basins in Indonesia, located in South East Sumatra block. Basal sand is a unique low resistivity reservoir in Asri Basin with thickness range 10-18 ft and permeability 68-240 md. Aryani AC-5, completed with frac-pack method, is the only producer well having produced from this layer. This well was shut-in since June 2014 due to DHP (Down Hole Problem). Reactivating the well become challenging due to monopod platform accessibility. Aryani platform can only be entered by jack up rig. A comprehensive and accurate approach is required to repair this well. First step is to revisit and recalibrate the permeability of Aryani AC-5. Previously, permeability of the well derived from normal parameter was 45 md. Calibrated with basal sand DST data in Aryani-1 (25 m from Aryani AC-5), permeability is adjusted to 96 md. DST data in Aryani-1 shows that basal sand producing with natural flow. Second step is to compare inflow performance relationship (IPR) curve before and after fracturing. The absolute open flow (AOF) potential after fracturing, 787 bfpd, is larger than AOF before fracturing (316 bfpd). This indicates better productivity as result of fracturing. Third step is to examine bubble map radius of the well. Using current cumulative oil production and recovery factor (RF) from J. J Arps equation, the radius length is 443 m. Meanwhile, length (one wing) of post job fracturing job is 41 m. This implies well reserves independent enough of fracture length radius. Remaining reserves of this well is calculated using Decline Curve Analysis based on historical performance. To summarize, several aspects are analyzed to confirm Aryani AC-5 reserves potential. Permeability data is updated with DST data offset well. Then, well productivity is proved by observing current IPR curve and before fracturing. Furthermore, bubble map radius larger than half-length fracturing job reassures its remaining oil. As a result, Aryani AC-5 is feasible to put on production.

AAPG Datapages/Search and Discovery Article #90354 © 2019 AAPG Asia Pacific Technical Symposium, The Art of Hydrocarbon Prediction: Managing Uncertainties, Bogor, (Greater Jakarta), Indonesia, August 7-8, 2019