Waterflood conformance is a significant problem in the West Sak field of Alaska. Re-assembling Pre-Formed Particle Gels (RPPG) have been used to treat Void Space Conduits (VSC) and repair the "short-circuited" waterflood. These VSC’s are typically formed by sand producing wormholes. Several dozen VSC solutions have been implemented since 2006, including molten wax, cement blends, and pre-formed particle gels. To date, all the solutions have been faced with various limitations due to the low reservoir temperature and poor sand consolidation. A good percentage of the pre-formed particle gel (PPG) solutions have been successful in sealing off VSCs, but often show limited longevity that can range from as little as several weeks to several years. An effort was undertaken to develop a product that would provide enhanced stability in the VSC and extend solution life beyond the current range. A cost-effective conformance solution was developed with increased mechanical strength through a re-crosslinking process known as RPPG. The goal of the RPPG solution is to provide a longer-term repair to a VSC and restore the primary water flood characteristics. This paper will present the results of the seventeen RPPG solutions that have been pumped between 2017 and 2019 in the West Sak field on the North Slope of Alaska. RPPG treatments have shown a 23% improvement over traditional PPG treatments at the economic payout during the field trial. There have been some significant learnings through this time period. The focus of this paper will be to review the VSC problem understanding and the reason for the RPPG product development, detail the evolution of RPPG job design over time and provide results and operational knowledge from the field trial efforts. The latest advancements in conformance engineering will be of interest to Reservoir and Production Engineers who are focused on supporting and optimizing conventional waterflooded assets, particularly when faced with conformance issues in an unconsolidated reservoir. In addition, the field results will be useful to those seeking to implement RPPG solutions in their area of operation.

This paper is a field case review of the process and methodologies used to identify, characterize, design, and execute a solution for a waterflood conformance problem in the Kuparuk River Unit in late 2013. In addition, post treatment analysis in a complex WAG flood will be discussed. The Kuparuk River Field is a highly fractured and faulted, multi-layer sandstone reservoir located on the North Slope of Alaska. Large scale water injection in the field was initiated in 1981 and overall the field responded favorably to waterflood operations. In 1996, Kuparuk implemented a miscible WAG flood in many areas of the field. However, natural fault and fracture connectivity has resulted in some significant conformance issues between high angle wells in the periphery. Methodologies employed to identify and characterize one specific conformance issue will be outlined. Details of diagnostic efforts, and how they were used to identify, characterize and mitigate an injector/producer interaction through a void space conduit will be discussed. The solution selected to resolve this conformance issue involved pumping a large crosslinked hydrolyzed polyacrylamide (HPAM) gel system. The solution used a tapered concentration design with one of the highest molecular weight HPAM polymers available. Before execution of this solution, extensive history matching and modeling of the solution design and benefits were used to justify this effort. These modeling efforts and their projections will be reviewed. This solution was pumped into the offending injector in late 2013, and offset producers were carefully monitored for gel breakthrough. The polymer treatment design parameters, including rates and pressure limits were used to generate an effective solution. A discussion of this active design approach, a complete review of the well problem dynamics, treatment operations, products used, and potential complications associated with these products will be discussed. Post solution execution performance analysis was difficult due to the active nature of this MWAG flood. A variety of plotting and analysis techniques were used to identify and quantify the results. A discussion of these results will be provided. Finally, a summary of lessons learned, and a limited discussion of future plans will be presented.

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This paper presents a field case study of conformance engineering efforts completed in the West Sak field throughout the past eight years. The West Sak field is a shallow viscous oil reservoir with poorly consolidated sand that has been under waterflood since 1998. Because of the nature of the formation and the completion techniques used, the field has experienced some severe conformance issues. Conformance candidate identification and selection criteria are reviewed followed by an overview of additional problem characterization efforts. A variety of solution designs considered and attempted are discussed with a summary of lessons learned from both failures and successes during this effort. This review discusses treatments that range from pumping graded CaCO3, molten wax, special cement blends, and, finally, preformed particle gels (PPGs) or water swelling polymer (WSP) crystals. A majority of these treatments were executed on horizontal wells, which required adjustments for some challenging placement control dynamics. A review of the efforts to control those placement dynamics is presented, discussing some potential problems associated with that control. The principle objective of this work was the elimination of open channels connecting water injection wells with oil producers. This connection eliminated matrix flow between the wells and threatened secondary recovery potential. Ultimately, the evolution of current solution treatments is provided with a brief benefit summary of the overall performance of this effort.

Formation powered jet pumps (FPJP) were pioneered for use in Kuparuk Field wells on the North Slope of Alaska. Unlike conventional surface powered jet pumps, these pumps are hydraulically powered by a prolific producing upper zone called the C sand to generate greater drawdown on a less productive lower zone called the A sand. Formation powered jet pumps increase oil rate from the A sand while reducing the water rate from the C sand.Gas lift can be used in formation powered jet pump wells to further enhance drawdown on a well while jet pumping. Many formation powered jet pumps are being used in Kuparuk wells with gas lift to increase the drawdown applied to the A sand.An overview of formation powered jet pumps used at Kuparuk Field is presented. Formation powered jet pumps could be beneficial in other multi-zone oil fields around the world to increase oil production rate, while reducing water production rate and lifting costs.