A Case Study for Effective Perforation and Gravel Placement in a Complex Dual Casing Completion

Abstract

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.