First Dual Zone Drillstem Test With Acoustic Telemetry Using Multiple Retrievable Packers for Single Trip Testing of Two Independent Reservoirs

Abstract

Although the main objectives of drillstem testing (DST) have remained largely unchanged over the years, operators are continuously seeking a means of improving operational efficiency (time/cost savings) while maintaining the highest level of operational standards, with safety and the environment being paramount. This paper presents a case history of the first retrievable dual packer testing string used to independently test two reservoirs in a single trip (toolstring conveyance into and out of the hole), which enhances operational efficiency. This case history is from an offshore exploratory well in Saudi Arabia in which a dual retrievable packer test string was deployed with a real-time telemetry system to successfully test two independent reservoirs in a single trip. Throughout the operation, real-time telemetry data above and below each packer enabled real-time understanding of the operational process and provided assurance of equipment/process integrity before proceeding with the next sequence of well testing operations. In this manner, operations were safely performed step-by-step, ensuring that the well test objectives and zonal isolation were met to determine the individual reservoir evaluation integrity. With the application of acoustic telemetry technology, the ability to acoustically communicate with and control downhole tools in real time is achieved. Communication to and from the downhole tools also provides the status of the downhole equipment in real time. In addition, knowledge gained from the real-time data enhances the ability of the operators to perform well tests with reduced uncertainties. The early availability of reservoir knowledge enables operational efficiencies, ensuring that test objectives are met, and may reduce the overall test period and significantly reduce well testing costs. The direct result of eliminating multiple trips is that operational efficiency is achieved, enabling the operator to save time and money without compromising data quality or health, safety, and environment standards. This case history represents a milestone for the industry, demonstrating the successful deployment of multizone testing, and serves as a stepping stone for even greater efficiencies by using real-time telemetry technology. This paper also discusses lessons learned and plans for additional well testing process efficiencies, enhanced with well application selection and DST toolstring acoustic control devices and technology.