Abstract
Abstract Robust and cost-effective water shutoff technologies are required to improve oil recovery and avoid challenges such as undesired water production. Herein, we present a new chemical water shutoff technology: A composite polymer gel system for carbonate substrate formation, from research work to successful field implementation. The composite gel with controlled gelation time was developed to isolate water production zones over various parameters, including temperature, pressure, injectivity duration, and flow rate. The rheological property of matured gels was investigated, such as the storage modulus (G'). In addition, a robust process was implemented based on rigorous job design and preparation, precise execution with real-time downhole monitoring, and thorough post-job analysis. Indeed, production logging and a noise tool were run to confirm the water entry and ensure good cement isolation behind the casing across the target zone. Laboratory results revealed that the gelation time can be controlled by varying the amount of fluid component, allowing a predictable pumping time at the given temperature between minutes to more than 10 hours. The gel system showed a significant pressure increase after the treatment, with good durability and effective water shut-off during the extended core flooding experiment. Thus, it is in alignment with gel strength testing. Hence, during the job mix adequate formulations based on the real-time downhole temperature, recorded while simulating the formation cooldown during treatment squeeze between retrievable plug and inflatable packer. The bottom hole circulating temperature and pressure were then measured in real time to adjust the water shutoff fluid formulations and to avoid exceeding the differential pressure limitation of the inflatable packer. After squeezing and waiting on the gelation of the water shutoff fluid in three stages, a successful pressure test demonstrated that the high water cut zone is reduced. Analysis of the pre and post job through rate test using downhole production logging tool (PLT); confirmed the success of treatment with a significant reduction in water production for more than 60%. The new trend of using in-situ composite gel incorporated with adsorption system is a breakthrough water shutoff technology. Utilizing laboratory coupled with field data collected before, during, and after gel injection along with proper diagnostic are the key elements to increase the success rate.
Published Version
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