Real-time downhole weight-on-bit and torque-on-bit measurements mitigates risks to ensure a successful completion string deploymentDownload PDF
Determine wellbore conditions to successfully deploy completion string
Gulf of Mexico
In a deepwater (water depth over 4,000 ft (1,219 m)) Gulf of Mexico subsalt wellbore, an operator sought to run its completion string in a very challenging environment. The upper borehole section had undesired tortuosity and high dogleg severity that had caused operational difficulties in the past. While running the completion string to bottom, it was difficult to monitor the mechanical force on the casing downhole and to have the ability to respond to changes without the use of downhole weight and torque measurements. The operator elected to utilize a downhole sensor system that monitored real-time weight-on-bit (WOB) and torque-on-bit (TOB) measurements to ensure that the string was deployed within the borehole mechanical limits for a successful completion operation.
In previous wellbores, the operator had problems getting its completion string to the bottom efficiently due to suspected wellbore tortuosity and undesired dogleg severity. This typically occurred in the upper borehole sections. It was noted in these sections that excessive WOB transfer had caused surface torque to exceed the drillpipe makeup torque, both of which are key factors in determining successful wellbore completion string deployment. Utilizing conservative values for friction factors, the standard torque and drag models determined that the operator would exceed the makeup torque specifications for the drillpipe. Through careful secondary analysis, the friction factors were adjusted and the makeup torque specifications were held within their limitations. The operator requested a validation method to ensure successful completion string deployment. Sperry Drilling was requested to provide real-time measurement solutions that would assure successful completion operations.
The Sperry Drilling team recommended the DrillDOC® drilling downhole optimization collar tool to provide real-time measurements of WOB, TOB, bending moment, and vibration to characterize the transfer of energy from the surface to the bit. This integration ensured that the full movement of the bottomhole assembly (BHA) was measured through all aspects of the cleanout run. Once these measurements were obtained, the operator would be able to compare the forces applied at the surface with the measured forces of the downhole BHA, and then can determine whether they were within the correct specifications to efficiently run the completion string as designed.
Feet water depth
Average weight transfer
During the cleanout BHA run, the DrillDOC tool measured less bending moment or dogleg severity than what the surveys had indicated, alleviating the concerns of wellbore tortuosity for completing the well. Sperry Drilling analyzed and compared WOB downhole measurements to the surface measurements, resulting in 81 percent average weight transfer and demonstrating that this weight transfer was enough to deploy the packer during the completion operation. Moreover, the TOB measurement coincided with the torque and drag model, demonstrating that there was going to be enough torque that could be applied to successfully run the completion. With this new approach of analyzing these downhole measurements, the operator had higher confidence to continue running the completion, and the well is currently producing as planned.
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