Success in deploying sand control systems is critical to guarantee the integrity of wells during their productive life. This is even more crucial when dealing with ultra-deepwater high-rate gas wells. This paper will describe the challenges and the lessons learned from the successful 2021 completion campaign of X field in East Africa in which six gas producer wells were completed with openhole gravel pack using shunt tubes technology in water depths ranging from 1840 m to 2149 m. The overall completion design philosophy was to rely on field-proven technologies and industry-accepted "best practices" to maximize safety and reliability. This objective was pursued in all phases of the project for timely completion of the wells while minimizing the chance of failure. Extensive testing on formation rock cores and completion fluids was performed before the start of drilling to identify the best sand control strategy and to avoid all potential issues such as formation damage or fluid incompatibility. State-of-the-art completion equipment was selected considering all potential contingencies associated with operations in an ultra-deepwater environment in a remote location. This document will describe the activities carried on during the different phases of the project: design, preparation, execution, and post-job interpretation. The goal of preventing solid production without impairing the well productivity was achieved successfully. This was confirmed from well testing interpretation where neglectable skin was detected. At the same time, it was possible to carry on the completion activities on time and on cost despite the remote location and the challenges related to the ultra-deepwater environment.

Perforation performance can be greatly reduced when encountering multiple casings where depth of penetration and crucially reduced entrance holes prevent effective gravel placement. A practically proven case study is presented on the design, equipment selection and execution of a successful cased-hole gravel-pack campaign in dual casing completions of an injector well. An integrated approach and workflow is implemented to enhance the gravel pack efficiency. It involves the combination of firstly, a high efficiency perforation system that optimizes tunnel geometry and penetration in a dual casing completion. Secondly, an innovative approach on the gravel pack installation using a viscous slurry to pump at slightly higher rates above the fracture gradient in order to create a small fracture around the wellbore. The success of the gravel pack installation is further assured by the application of an “alternate path” concept. Packing the perforation channels is achieved by selecting a big-hole gun system that provided optimal performance through the multiple casings including highly phased large casing exit holes resulting in a large area-open-to-flow. The cased hole gravel pack completions is installed using a high rate gel pack technique creating short, highly conductive fractures enhancing connection of the reservoir to the wellbore. Furthermore, annular pack integrity is achieved using an alternate path design ensuring uniform gravel placement over the sizable reservoir interval. Injectivity into the formation is proven via constant tubular and annular pressure; indicating minimal permeability impairment to the formation. The production zone is flow tested using an electric submersible pump with trace of solids 0.01% WT received at surface confirming the integrity of the gravel pack completion. With the increase of more complex reservoirs and completion techniques, practical application and solutions of such complexities add to the industry knowledge base. This paper shares a practical and proven integrated approach to providing solutions for installation of gravel pack in a dual-completions. This concept is based on many years of operational experience and lessons learned on the field.