This paper discusses a unique introduction of modular screens into the design of a deep water horizontal open hole injector completion offshore Nigeria and describes the complete quality assurance/quality control (QA/QC) and operational procedures of the first global deployment of modular screens with sliding sleeves. The Egina field, initially designed without a provision for mechanical or hydraulic isolation of panels, provided an opportunity to introduce a means of accomplishing isolation with modular screens and mechanical actuated sliding sleeves.
This application provides the operator with the ability to (1) selectively inject into different intervals using mechanical intervention and (2) address erosion concerns on a high rate water injector without compromising the current upper completion (UC) and existing wellhead design. The paper details the successful installation, excellent completion equipment functionality, and well results.
The operator's geosciences team targeted two separate reservoir panels in the Egina field for water injection. However, commingled injection into both panels would result in an early water breakthrough at one of the supported producers, causing a large loss in oil recovery. The current design for Egina does not provide a means of temporarily isolating the heel section while allowing communication into the toe during injection. Rather than drilling two separate water injectors at significantly higher costs, the completion team identified a solution combining the two targets into a single well while maintaining the ability to temporarily access, isolate, or isolate one interval. The team introduced a viable means to selectively inject by adding modular screens with integral sliding sleeves. The revised completion design used existing materials applied on earlier completions, which maintained complete compatibility with the UC and the existing wellhead configuration.
Modular screens have long been used in cased hole gravel pack applications where multi-zone selectivity has been necessary. Applying this technology to a horizontal open hole scenario allowed the team to selectively inject into one interval and then return later to subsequently inject into the next interval using sliding sleeves. Injection rates vary based upon the number of sliding sleeves opened or closed. The subject well was run with a modified lower completion (LC) incorporating modular screens in the upper interval and standard wire-wrapped screens in the lower interval with a swell packer providing isolation of the two. This modified completion design allows for an adjustable rate for either individual or commingled injection through a mechanical intervention, and it provides a completion that can be deployed and installed in an efficient manner without any operational issues.
Successful installation and injectivity testing have proven the completion concept, and have helped in providing a technical solution allowing the operator to recover the 3-Mbbl oil stake associated with water injection into the upper interval. The sliding sleeves incorporated into the system were manipulated opened and closed with no issues, and injectivity tests were performed with excellent results.