Surveillance Optimizes Development Plan for a Deepwater Reservoir
Authors: Carpenter Chris 
Published: March 2023

_
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 210274, “Effective Use of Surveillance To Optimize the Development Plan for a Deepwater Reservoir,” by Cengiz Satik, SPE, Matthew Burgess, SPE, and Matthew Carter, Chevron, et al. The paper has not been peer reviewed.

_
A three-phase strategy was adopted for a deepwater reservoir development as a result of large uncertainties associated with fault compartmentalization and aquifer support. The first phase began with primary production from several wells, while water injection was implemented a few years later as a second phase. The third and final phase involved infills. Data collected during drilling were used to improve reservoir characterization. The complete paper describes how a surveillance, analysis, and optimization plan resolved key subsurface uncertainties and optimized the development plan and presents lessons learned and best practices.

Introduction
The field is in the central Gulf of Mexico Green Canyon. It produces from a series of stacked subsalt reservoirs consisting mainly of lower-slope to basin-floor turbidite sands. Uncertainty in flow behavior exists in prospective areas near low-confidence faults, affecting well performance and ultimate recovery predictions.
To improve reservoir characterization and enhance field-performance predictions, a full-factorial 3D static Earth model was built by integrating well, surveillance, and seismic data. Dynamic simulation was used to help calibrate the well and field historical performance, forecast future recovery, and highlight and test potential opportunities. Despite achieving acceptable history-matched simulation models, specific development scenarios presented large recovery uncertainties and varying economic outcomes. In this work, results from reservoir surveillance modeling and execution were used to narrow the range of recovery uncertainty and improve field-development decisions. Dynamic reservoir-surveillance techniques, such as interference and pulse testing, used in this study provided key evidence that reduced fault compartmentalization uncertainty significantly and eliminated the need for a costly infill well to recover remaining resources. Furthermore, increased confidence in recent seismic-imaging enhancements has since corroborated these results.

Opportunity
The reservoir is the deepest producing reservoir in the field. It consists of two distinct and vertically separated zones. Southwest of the historical production from Reservoir 1, existing fault interpretation from seismic imaging placed three faults (Faults 1, 2, and 3), creating several compartments within the area (Fig. 1). An infill drilling program was progressed to drain the resources from these compartments. Well 1 was completed only within Zone 1 (upper zone). As shown in Fig. 1, Well 2 was a new drill between the interpreted Faults 2 and 3. It was completed as an intelligent well perforated along both zones of the reservoir. The length and transmissibility of all three faults, as well as the reservoir heterogeneity within the area, were highly uncertain. Consequently, previous development plans placed a potential infill well between Fault Blocks 1 and 2 to drain the volume within the compartment bounded by Faults 1 and 2. However, reservoir simulation studies indicated that recoverable resources from this future infill well were highly dependent on the sealing nature of Faults 1 and 2.