How Subsurface Integration Helped Improve Value in a Troubled Asset
In 2015, an 18 well plan in the heart of an ongoing waterflood development of PDO’s Reservoir “A” was found to be at risk when new penetrations showed severe reservoir pressure depletion. Further investigation revealed that the reservoir was in pressure communication with an underlying unit (Reservoir “B”) that has been under development since 2009. Reservoir B was developed using a different well spacing and orientation than the pending development planned for Reservoir “A”. The 18 well plan was halted while an integrated subsurface review was conducted. There were four key recommendations from the study, which are as follows: 1. A revised geological concept wherein the intervening tight limestone barrier between the two reservoirs was remodeled to pinch out such that the two reservoirS merged to form a single unit to the north of the development area, 2. A recommendation To align the Reservoir “A” development wells with existing Reservoir “B” development wells (WI over WI; OP over OP) and therefore to defacto change the well spacing from the original FDP for reservoir “A”. This also led to a reduction in the number of wells from 18 to 14. 3. To drill water injectors ahead of the oil producers so as to allow time for reservoir pressure to build up above bubble point 4. To operate the existing reservoir “A” wells in the area on a cyclic basis; ie. two weeks on and two weeks off until reservoir pressure from the above implementations built up above bubble point Since the end of 2016, all 14 wells have been executed, and after operating most of the oil producers on a cyclic basis for the first half of 2017, recent pressure measurements show that GOR has steadily declined. Consequently, most wells are on continuous production and producing at oil rates that represent a 100% improvement from 2015. It is estimated that the outcome and implementation of the integrated study have led to the asset realizing an incremental NPV of 30% as compared to a scenario where no optimization would have been done to the original 18 well plan.
AAPG Datapages/Search and Discovery Article #90328 © 2018 AAPG Middle East Region GTW, Maximizing Asset Value: Integrating Geoscience with Reservoir Management & Facilities Optimization, Muscat, Oman, April 30 – May 1, 2018