Managed-Pressure Cementing Implemented in an Exploratory Ultradeepwater Well
Authors: Carpenter Chris 
Published: June 2021

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30481, “Successful Managed-Pressure Cementing on an Exploratory Well Operation in Ultradeep Waters of Mexico,” by Raul Bermudez, Juan Jose Ferro, and Cyril Szakolczai, Total, et al., prepared for the 2020 Offshore Technology Conference, originally scheduled to be held in Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission.
The focus of the complete paper is the planning and execution of an ultradeepwater managed-pressure-cementing (MPC) job in the Gulf of Mexico. From the onset of planning, the base case was to integrate a managed-pressure system into the drilling program to mitigate predicted pore-pressure (PP) uncertainty, pressure ramp increase, and narrow PP/fracture-gradient (FG) window operations, including drilling, tripping, and running casing. Although MPC was not originally in the scope of work, it was required because of the tight drilling window and was successfully executed.

Introduction
The well is in Mexican waters at a depth of 10,748 ft. Given the exploratory nature of the well, a pressure ramp was predicted that would demand an excessive number of casing strings if a conventional approach were used. During the drilling phase—taking advantage of the ability to adjust the bottomhole pressure instantaneously—dynamic PP tests were performed to conclude that the expected pressure ramp was not aggressive but was leading to a narrow window that would not allow conventional cementing of the 13⅜-in. casing.
Strategic planning and close collaboration between the operator’s engineering and operations teams, the cementing service provider, the managed-pressure-drilling (MPD) consultant, and the MPD service provider team was required. The uncertainty about the actual size of the hole led to an even more challenging MPC engineering analysis. The result of this cementing job was a success with no fluid losses, resulting in good zonal isolation.
The specific objective for the MPC application was to set a 13⅜-in. casing to isolate the critical formation and safely continue drilling further stages of the well with an improved leakoff test at the shoe. Planning and design of the MPC application is detailed in the complete paper.
This job represented the greatest water depth, and first from a drillship, for an MPC job performed by both operator and MPD service provider. In addition to performing a critical cementing operation using the managed-pressure approach, reaching well-construction objectives using MPD also was achieved while avoiding the use of a contingency liner, which saved significant expense.
The base case was to integrate an MPD system into the drilling program to assist with PP uncertainty, pressure-ramp increase, and narrow PP/FG window operations, including drilling and tripping. The main objective for using the managed-pressure system during cementing was to ensure that the equivalent mud weight (EMW) at both total depth (TD) and the previous casing shoe did not fall below set limits throughout the job. The secondary objective was to reduce or eliminate losses during this process.