Abstract

The operation described in this paper is related an ultra-deep-water exploration well drilled in the Mexican waters of the Gulf of Mexico (GOM) and the first drilled by the operator in the area. From the onset of planning, the base case was to integrate a Managed Pressure Drilling (MPD) system into the drilling program to assist with pore pressure uncertainty, pressure ramp increase, and narrow Pore Pressure/Fracture Gradient (PP/FG) window operations including drilling, tripping, running casing and cementing, with the latter being a procedure that was not included in the initial stages of the project but discussed and implemented during the execution phase (Moghazy et al. 2018, Gradishar et al. 2017).

The well is located in a water depth of 3,276 m (10,748 ft). Given the exploratory nature of the well, there was an assumed pressure ramp that would demand an excessive number of casing strings with a conventional approach using an overbalanced Mud Weight (MW). During the drilling phase and taking advantage of the ability to adjust the bottom hole pressure instantaneously, dynamic pore pressure tests were performed to conclude that the pressure ramp was not as aggressive but lead to a narrow window that would not allow conventional cementing of the 13-3/8-in. casing.

Strong planning was required between the operator's engineering and operations teams, cementing services provider, MPD consultant, and MPD service provider team. The uncertainty about the actual size of the hole yielded an even more challenging Managed Pressure Cementing (MPC) engineering analysis (Valecillos and Craigh 2016). This cementing job was a success with no fluid losses, a hazard that had been assigned a high probability.

The specific objective for the MPC application was to set 13-3/8-in. casing to isolate the critical formation and to safely continue drilling further stages of the well with an improved Leak-off Test (LOT) at the shoe.

This job represents the deepest water, and first from a drillship, for a managed pressure cementing job performed by both operator and MPD service provider. Additionally, a critical cementing operation was successfully performed using the Managed Pressure (MP) approach. The well construction objectives using MPD were also achieved while avoiding the use of a contingency liner which saved an additional USD3.5 MM from the planned AFE (Hernandez and Valecillos 2018).

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