Successful Testing of Single Gradient Subsea MudLift Drilling Technology in Deep Water Gulf of Mexico

Abstract

Abstract Subsea MudLift Drilling (SMD) technology is a form of Managed Pressure Drilling (MPD). Similar to other MPD systems the SMD technology offers early detection of influxes (kicks) and minimizes downhole losses to weak sub-surface formations. However, very significant and beneficial differences are built into the SMD system. Two variations of Subsea MudLift Drilling techniques are currently being tested in deepwater Gulf of Mexico: SMD Dual gradient (SMD-D) technology also known as dual gradient drilling, andSMD Single gradient (SMD-S) technology also known as single gradient managed pressure drilling. In deepwater drilling operations, the effect of annular friction pressure (AFP) often reduces the drilling window between pore pressure and fracture pressure. The SMD-S technique allows for the reduction of the dynamic bottom hole pressure by pumping off a portion of the AFP while drilling. Through greater management of the bottom hole pressure, this technology enables efficient navigation between the pore pressure and fracture gradient profile. As a result, tremendous value can be realized through reduction of non-productive time and the drilling cycle time. Further, the technology may enable drilling highly deviated extended reach wells in a deepwater environment, which can potentially increase total recovery with reduced well count. The SMD-S system was successfully tested on one of Chevron’s Deepwater GOM exploration wells. This deployment was the penultimate step in an extensive testing and qualification process to ensure the equipment functioned in accordance with all required design conditions, and that the operational procedures allowed for delivering a well safely. In addition to training key operator personnel, rig contractor, and service company personnel, engagement of third party reviewers and regulatory agencies was critical throughout the process. Lessons learned were recorded and corrective actions implemented throughout the process, from initial testing at the component level through the subsea deployment of the entire system. As these items are addressed and incorporated back into the equipment design, training, and operational procedures, a plan is in development to drill an entire well utilizing the SMD-S technology. This paper will highlight the benefits of SMD-S technology, the execution of the most recent deployment and test results that are the final steps in moving towards continued managed pressure drilling operations in the deepwater GOM.