Korolev Field is a naturally fractured carbonate reservoir with 1.5 Billion barrels original oil in place, under primary depletion since 2001. Full field water injection is a potentially feasible Improved Oil Recovery (IOR) method to improve Korolev ultimate recovery. A continuous water injection pilot project is being proposed, with the objective to reduce subsurface uncertainties impacting the incremental recovery from full field waterflood investment.
This paper will present two different methods used to assess the Value of Information (VOI) for the Korolev water injection Large Scale Pilot (LSP): 1) the traditional VOI approach; and 2) the Ensemble Variance Analysis (EVA) based VOI approach. Pilot data collection and interpretation enables improved full field development decision which is the source for the pilot Value of Information.
VOI comes from the ability to improve full field development economical outcome by making a better decision based on Pilot information. For the traditional VOI approach, establishing a set of clear signposts from a robust surveillance plan is the key for appropriate pilot indication reliability assessment to full field reality outcome. To capture the full range of full field reality outcomes, ranges of each subsurface uncertainty were tested in the Brownfield history match, and the waterflood incremental recovery S-Curve was generated from the full suite of history matched reservoir models. In the EVA VOI approach, pilot indications are represented by the post-pilot waterflood incremental recovery S-curves after history matching to an ensemble of pilot data sets.
A thorough and robust surveillance plan and associated signposting is required for meaningful VOI assessment. Pilot reliability is assessed by multi-disciplinary team based on clear definition of P10, P50, P90 Pilot indication with traditional VOI approach. The traditional VOI method yields very comparable results with EVA based statistical Pilot reliability for the Korolev LSP, which gives the confidence to continue using EVA-based VOI for pilot strategy alternative selection.
EVA has been a recently developed method for Pilot VOI assessment. This is the 1st paper which compares EVA method with traditional VOI on pilot reliability assessment.