Waterflooding Optimization: A Pragmatic and Cost-Effective Approach to Improve Oil Recovery from Mature Fields

Abstract

This paper presents selected effective technologies and best practices to improve oil recovery from mature fields through waterflooding optimization. These technologies are proved practical, applicable and cost-effective. They can effectively facilitate further development of mature fields, which is more important than ever before in the current economical down-turn environment. First, this paper summarizes and discusses several pragmatic approaches to optimize waterflooding of sandstone reservoirs. These methods have proved to be beneficial for expanding sweep, thus increasing ultimate recovery. Next, the authors introduce two methods to evaluate the effectiveness of application of these technologies, which can support both qualitative evaluation of the successfulness of the applications; and quantitative estimate of incremental recovery. Finally, this paper illustrates the best practices of each waterflooding optimization technology and the associated reservoir dynamic performance. Waterflooding optimization aims at expanding volume sweep to recover bypassed oil in undrained areas or remaining oil in poorly swept areas. The main established approaches include (a) zonal water injection, (b) changing direction of fluid flow, (c) subdividing injection-production unit, (d) water shut-off to improve areal sweeping efficiency, and (e) cyclic water injection. These techniques are particularly applicable to multi-layer, vertically and laterally heterogeneous reservoirs at the high water-cut production stage. One best-practice example shows that converting comingled water injection into zonal injection has successfully arrested production decline, and resulted in an 11.8% incremental recovery. In another reservoir with 98% water cut and 54.5% recovery of changing injection direction by modifying well pattern has led to a 10% incremental recovery by. In still another example, subdivision of injection-production unit combined with infill wells has achieved incremental recovery ranging from 9% to 20%. A further case illustrates that, compared with continuous water injection, cyclic injection had led to reduced water production, lowered water-cut and increased recovery, and resulted in an incremental recovery of 1.84% EUR. To conclude, maximizing reservoir sweep efficiency is the core step of waterflooding optimization. The techniques and best practices discussed in this paper possess both technical and economic viability. Effective application of those methods is an essential part of profitable reservoir management of mature fields.

Evaluation of Intelligent Wells Performance in a Five-Spot Arrangement

“…Several remedies have been proposed with regards to the potential problems associated with water flooding. One among them that stands out and receiving research attention is the use of smart or intelligent production and injection wells (Brouwer et al, 2001, Meum et al, 2008, Volcker et al, 2011, Grema and Cao, 2016, Grema et al, 2016a, Lu and Xu, 2017, Ogbeiwi et al, 2018, and Hourfar et al, 2019. Although known for its attendant limiting productivity and lack of susceptibility to optimization techniques, conventional wells are more predominant.…”

Techniques for improving the water-flooding of oil fields during the high water-cut stage

“…The CRM can characterize the dynamic connectivity of the injection and production wells in the reservoir, and it can analyze the influence of the injection and production imbalance on the liquid production [8][9][10]. In order to optimize water-flooding of sandstone reservoirs, Lu and Xu summarized several sophisticated approaches, including zonal water injection, changing the direction of the fluid flow, subdividing the injection-production unit, water shut-off to improve the areal sweeping efficiency, and cyclic water injection [11]. These techniques are particularly applicable to multi-layer heterogeneous reservoirs in the high water-cut production stage.…”