A Case History - The First Successful Managed Pressure Cementing Operation in Over-Pressure and Narrow Drilling Window Environment Using Swamp Barge Drilling Rig, Indonesia
Authors: Yasmin Kharisma Asri , Zein Joydi Mirza , Lubis Defry Erwinsyah Umra , Prasthio Andry , Faradilah Ariyati 
Published: October 2023

The case presented in this paper is an HPHT exploratory well in East Borneo. This well was designed to drill a potential gas reservoir using MPD system to encounter the narrow operational window formation. An unexpected high pore pressure increase was detected while drilling the 8.5-inch hole section, resulting in a tighter window. The pore pressure below 9-5/8-inch casing shoe was measured to be 2.18 SG, up from 2.09 SG preliminary expectation. Because of this condition, it was decided to call in TD earlier and cement the open hole section using managed pressure cementing.

Conventional cement operation wasn't viable due to the required mud weight increment and the resulting equivalent circulating density with 7-inch liner at the bottom, which limited the likelihood of success. Cement slurry and spacer must be designed to stay within the pressure window during static and dynamic conditions. Initially, the use of high-strength, low-density slurry weighted was also contemplated. However, because to the additional time and specialized needs for this cement-slurry combination, the idea was canceled. The decision was subsequently made to use MPC to maximize the likelihood of successfully installing a barrier through the 7-inch liner shoe.

Managed pressure cementing occasionally implemented in specific drilling conditions. Nowadays, this technique has been more frequently applied in most MPD operations. Despite its unconventional condition, exerting SBP while cementing operation guarantees cementing improvement behind each casing.

During the engineering and planning phase, the target ECD for cementing was established by discussions and reviews with all service companies involved. The anchor point used was defined at 9-5/8-inch shoe depth which was suitable to avoid undesired wellbore-fluid influxes and losses. The anchor point is a set depth in an open hole where ECD values are maintained constant using the MPD choke to produce overbalanced circumstances without exceeding the fracture gradient.

Before executing cement operation, a dynamic formation integrity test (DFIT) needs to be conducted in order to identify and confirm the strength of the shoe at any open hole depth. DFIT is essential to confirm the anticipated pressure that can be applied to the formation.

During implementation, the final surface backpressure schedule was fine-tuned after DFIT and using the MPD software which is completed with its delicate control system, as the primary operational reference. Because of the narrow operational window, the 7-inch liner was run in managed pressure mode, controlling the stripping speed and adjusting SBP increment using the MPD system choke control to maintain the ECD.

This paper describes the detailed engineering and MPD application from conceptual, preparation, and execution, along with its results and lessons learned.

This manuscript elaborates the first successful MPC operation deployed with Swamp Barge Rig, which enabled liner cementing at narrow pressure windows efficiently and time-saving for the the operator.