Successful Managed Pressure Cementing on an Exploratory Well Operation in Ultra-Deep Waters of Mexico

Abstract

The operation described in this paper is related with an ultra-deep-water exploration well drilled in the Mexican waters of the Gulf of Mexico and the first drilled by the operator in the area. From the onset of planning the base case was to integrate a Managed Pressure system into the drilling program to mitigate prognosed pore pressure uncertainty, pressure ramp increase, and narrow PP/FG window operations including; drilling, tripping, running casing. Although Managed Pressure cementing was not originally in the scope of work, it was required due to the tight drilling window and successfully executed.

A narrow pressure window (1.07 sg – 1.13 sg) encountered in the 12-1/4" × 16-1/2" section resulted in the managed pressure system being required to run and cement the 13-3/8" casing string while managing the annular pressure profile. Placement of the cement was critical to isolate a permeable zone below the previous casing shoe and reduce the chances for aremedial cement work. The main objective for using the MP system during cementing was to ensure the EMW at both TD and the previous casing shoe did not fall below the set limits throughout the job. While the secondary objective was to reduce and/or eliminate losses. With the total depth being 4,151m, water depth of 3301m, surface mud weight 1.03 sg with down hole equivalent mud weight of 1.047sg due to compressibility and temperature.

The main objective for using the MPD system during cementing was to ensure the EMW at both TD and the previous casing shoe did not fall below the set limits throughout the job. While the secondary objective was to reduce and/or eliminate losses. With the operator depth being 4,151m (13,619 ft), water depth of 3,276m (10,748 ft), surface mud weight 1.03 SG (8.58 ppg) with down hole equivalent mud weight of 1.047SG due to compressibility and temperature

Planning for the job required input and collaboration from various personnel from the operator as well as third party services working together to run simulations, calculations, and analyses to create a detailed program. With the casing on bottom, the execution phase of the operation again required significant planning and organization on the rig to successfully implement and execute the step by step instructions for the job. MP cementing was executed as planned, with no losses measured, following the displacement sequence and surface backpressure step down until observing the plugs bump. Zonal isolation was achieved, confirmed through an adequate pressure test of the casing, as well as, a sufficient FIT to drill the subsequent section.

The focus of this paper is on the planning and execution of an ultra-deep water managed pressure cement job drilled in the Mexico side of the Gulf of Mexico. Learnings and observations were collected during the planning and execution phases. These learnings may assist other managed pressure operations to successfully implement and execute MP cement on ultra-deep water operations in the future.