Cost-Effective Innovation Qualified as Bidirectional Barrier to Support Well Cost Reduction, Eliminate Slickline Operation, and Improve Robustness of Interventionless Systems Application in the Market
Authors: Abu Bakar A. M. , Yahaya F. , Abd Shukor M. S. , Ghani S. , Bakar F. , Ariffin A. , Rodzi M. E. F. M. , Sooriaprakash P. G. , Misron M. A. , Bela S. M. , Jailani N. S. , Idris N. M. , Zaman H. K. , Azmi N. F. , Mazlan S. S. 
Published: October 2023

Objectives/Scope
Conventional Back Pressure Valve (BPV) is not a certified barrier for development wells in Operator's internal guidelines due to its inability to test from the direction of flow. According to industry standards, two independent barriers must be present to prevent well control scenarios. Traditionally, a deep plug set by slickline is used as the first barrier and Tubing Retrievable Surface-Controlled Subsurface Safety Valve (TRSCSSV) act as the second barrier prior nippling down of BOP. To enable full-fledged interventionless approach, a barrier-rated tubing hanger valve has been successfully invented to eliminate slickline intervention and minimize associated risks and operation time. This tubing hanger valve is a bi-directional well barrier element qualified according to API 6A: Specification for Wellhead and Tree Equipment, and some of the acceptance criteria in API Spec. 19V: Subsurface Completion Isolation (Barrier) Valves and Related Equipment in both gas and liquid. Although it is not a subsurface plug, the operator decided to perform the qualification as per API 19V to have a more stringent verification and acceptance criteria that equivalent to the certification of a downhole barrier-rated plug.

Methods, Procedures, Processes
The technology incorporates an inner plug and equalization features that relieve the pressure surges during plug removal. It can be set and retrieved mechanically in a single run using a dry rod at the Universal H-type profile tubing hanger. Conventional BPV is not barrier-certified, especially for small-sized tubing-conveyed downhole plugs (2-7/8″ and 3-1/2″), and those that are barrier-certified commonly for larger tubing sizes are set with slickline and come with higher risks. The operator had piloted this tubing hanger valve at one of the offshore wells and obtained TRL6 endorsement after the successful trial installation.

Results, Observations, Conclusions
Based on the pilot installation performance, projected cost savings for one well from operation simplification and rig time reduction are expected to be around 86% compared to conventional slickline run for 3-½″ tubing sizes, with up to approximately 10 hours rig time saving.

Novel/Additive Information
The technology also eliminates the need for expensive interventionless barrier-rated downhole plug technology by presenting opportunities for the utilization of more cost effective, non-barrier-rated downhole plugs to set the production packer. It also allows for well killing operations via thru-tubing kill fluid pumping. For well intervention operations, the innovation allows for quick rectification of well integrity issues related to tree valve and faster mobilization of equipment without the slickline package. The equipment's smaller footprint makes it suitable for use on small jacket and satellite platforms, as well as providing the first barrier for wells under temporary suspension (mothball) which can be easily monitored by pressure equalizing features. This eliminates the need to mobilize slickline units for deep set plugs.