Abstract
In Burhaan west field, Oman, the contribution of zones in multistage fracturing is critical information during well evaluation. Although many methodologies are available to evaluate zonal contribution, all have some disadvantages, particularly in application to tight gas wells; therefore, an integrated surveillance is required to confirm the result. Understanding the zone contribution provides a greater understanding of the reservoir and geological features and promotes a successful fracturing result.
The development strategy of tight gas often requires close-to-real-time post-fracturing performance following multistage fracturing due to the shut-in period limitation of the fractured wells. The result is important to improve the target reservoir development strategy of the entire field. A chemical tracer in combination with a memory production logging tool (MPLT) was selected as a solution to this challenge. A unique oil and water tracer pair was pumped during the main treatment of the stage for post-fracturing flow profile mapping assessment. In addition, a sampling campaign was initiated to identify potential communication and crossflows. The memory production logging tool was then run to provide the flow confirmation of each zone.
The overall process decreased the operational time and the learning curve and refined geological assumptions without sacrificing the effectiveness of the fracture treatment in terms of conductivity and gas recovery. The tracers’ data integration with the MPLT data helped to improve the target reservoir development approach and provided a continuous performance flow profile for the long term. The data were used to optimize the 3D fracture modeling and design, achieve the best flowback strategy, and significantly enhance the understanding of the reservoir geology for the field. In addition, analysis of the chemical tracers over several months provided insight into the continuous flow profiles leading to optimizing fracturing performance and design strategy in the field on a regular basis, based on the updated result.
Since the Burhaan Northwest high-pressure high-temperature gas wells are being completed with multistage cemented fracturing designs rather than openhole stimulation, a chemical tracer in combination with the memory production log played a key role in delivering zone contribution data. Results of the work include documentation of the step-by-step planning and surveillance setup of the zone contribution in combination with the outcome achieved and the usefulness of the data.