Unique Mechanically Selective Water Injector Completions Deployed Washpipe Free
Authors: Okpalla Chinedu , Perez-Fernandes Maria , Achich Achref , Johnson Kenneth , Okengwu Victor , Allen Clifford , Hanson Jon-Howard , Novelen Ryan 
Published: August 2020

The unique introduction of production screens with mechanically shiftable flow isolation sleeves and inflow control devices for better injection flow distribution (ICD) fit with innovative dissolvable metal plugging rods that allow wash pipe free horizontal completion installation on a deep offshore project in Nigeria. This unique application provides the function of a mechanical selective completion with the incorporation of an ICD solution tailored to the reservoir with wash pipe-free execution. This would allow for selective injection from one zone to a comingled injection activated using mechanical intervention means while maintaining full compatibility with the already designed upper completion and the existing wellhead and topside equipment, as is. The completion was successfully installed following the standard field operations practices used on previous completions within the same field.

The Egina development plan, operating with a standardized and simple design, does not provide for an intelligent completion that allows remotely activated zonal selectivity. Two separate reservoir zones, with two panels each, were targeted for water injection to achieve the sweep of by-passed oil in the shallower panels connected to two producer wells and pressure mainteneance in the deeper panels connected to one producer well. Commingled injection from start would result in early water breakthrough on one of the two producer wells connected to the shallower reservoir panels by virtue of both well drains being almost at same level depthwise, TVD/MSL. A solution was selected that would combine the two target reservoir zones on a single well. This would allow for selective injection using screens with mechanically shiftable integral sliding sleeves, maintaining temporary access or isolation on the shallower interval. This solution would allow for drilling one single water injection well instead of two.

Incorporating ICDs in the deeper reservoir panels with "a dissolvable plug solution" allowed for a better injection flow distribution as well as the completion deployment, wash pipe free. Fluid compatibility testing was performed with dissolvable metals to establish dissolution rates under existing reservoir conditions with mud, brine, and filter cake breaker at field standard formulations. This provides an additional option for running wash pipe free when running lower completions in deepwater wells offshore West Africa. Drilling one well instead of two and deploying completions wash pipe free, allowed for CAPEX savings in the region of $60 Million.

No modification to the existing completion processes was necessary with respect to the procedure for deploying completions, washing down or subsequently placing a filtercake breaker treatment.

This paper describes the rationale behind the well design philosophy and the operational procedures that introduced a global first deployment of injection screens with mechanically shiftable integral sliding sleeves and ICDs with dissolvable plugs in deep water openhole horizontal completion. The successful installation, completion equipment functionality, and well injectivity test results are discussed.