This paper presents how a Controlled Mud Level (CML) Managed Pressure Drilling (MPD) system was used to place Horizontal Open Hole Gravel Packs (HzOHGP) in low Pore Pressure Frac Gradient (PPFG) margin reservoirs. This industry-first accomplishment took extensive preparation and precise on-site coordination between CML and gravel pack operations. In the target reservoirs, the margin between the pore and fracture pressures is too small to place gravel packs using conventional methods. CML was identified as an opportunity to resolve this problem. A primary design phase goal was to develop a deep understanding of the flow paths and fluid properties at every stage of the gravel pack operation. This information is critical to evaluating the frictional pressure drops effecting the pressure in the open hole. The team developed procedures that incorporated step rate tests and real-time downhole measurements to calibrate the friction models, which were then used to precisely control the CML during the pumping jobs. CML was able to limit the downhole treating pressures to stay within the low PPFG limits. The post-job analyses showed that total screen coverage was achieved for all the jobs in the campaign, demonstrating the project team's high level of coordination, cooperation, and cross-discipline understanding. While the industry had adopted CML and HzOHGP systems separately prior to this project, this operation marks the first time they have been combined.

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