Successful Installation of the First Deep Water Single Trip Stand- Alone Screens in the Industry Saves Rig Time on Bonga Project.
Authors: Ojeh-Oziegbe Osehojie , Olatunji Idris , Alawode Olusiji , Walker John , Murdoch Euan , Patel Dinesh , Aye Yeneapre Apremu 
Published: April 2019

Every field development requirement is to keep the capital and operational expenditures (CAPEX and OPEX) within reasonable limits, at the same time exploring matured or new technology that can achieve cost limit objectives.

With the uncertainties, cyclic nature and instability in the oil and gas global investment and the fluctuation in crude oil pricing, operators of the exploration and production (E&P) energy industries and service providers are constantly looking for better and more efficient cost saving products and services. The challenge of maximizing hydrocarbon recovery in deep water completion with minimum investment, while maintaining the highest level of Health Safety and Environment (HSE) and service delivery always leads to new products and service delivery techniques.

In the operator's Bonga subsea field, the conventional completions technique for all open hole Standalone Screen (SAS) completion installations are performed in multiple trips. The first trip involved running a gravel pack packer with screen assembly which allows a gravel pack packer service tool and an internal string with a pump thru wash-down capability enable ease of deployment, toe-heel circulation, packer setting and testing. The internal string which comprises of the packer setting tool, internal wash pipe and accessories is recovered after completion of the first trip into the open hole formation section. The second trip involved running the production tubing, production packer, downhole gauge mandrel, safety valve and other completions accessories and landing the production string on the tubing hanger.

The major objectives and drivers of the open hole Single Trip Stand-Alone Screen completion (STC-SAS) in deep offshore environment is basically to save rig costs, use proven and emerging technologies, employ completions best practices, reduce exposure of personnel to safety hazards and of course reduce Non-Productive Times (NPT). New completions technique with different services and product providers could pose a challenge in terms of vendor interface management, equipment compatibility and procedural integration of multiple downhole equipment with different operating boundaries and limits.

The single trip stand-alone screen completions concept in deep water was generated by the operator's Wells Front End Completion and Well Intervention team in December 2015. This was driven by an opportunity to further reduce well delivery rig time which is a premium in deep water subsea completions. The average completions time in the field stood at 10 days per 10,000ft well. The group was challenged to further improve the well delivery time. However, there was no bench mark as the industry data showed that a single trip open hole stand-alone screen completion had not been installed globally in deep water subsea environment.

This paper presents the evolution of the completions design, the critical challenges in the contractor management, downhole equipment interfaces, operational steps, risks and the lessons learned during the job execution that led to the successful installation of the first single trip open hole sandface STC SAS in deep water environment.