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Enhancing Offshore Recovery by Enabling Longer, Safer, and Cheaper Subsea Well Tiebacks
Project Number
DE-FE0031859
Last Reviewed Dated
Goal

The objective of this project is to design, engineer, construct/fabricate, test and qualify a full scale prototype subsea chemical storage and injection system (Subsea-Shuttle) for low dosage rate production chemicals to enhance offshore oil production. Offshore, ‘enhanced oil recovery’ can be the difference between economically drilling a subsea well and achieving primary and often secondary (usually water injection) recoveries (50/60%) versus leaving the resources in the ground (0% recovery) due to the high cost of dry tree, platform supported wells. The project goal is to develop and qualify this new technology which will help reduce the cost of subsea well tie-backs and extend their reach to unlock stranded resources.

Performer(s)

Subsea Shuttle LLC, Houston, TX 77024-5719

Collaborators
Genesis, Houston, TX 77027
Seanic Ocean Systems, Katy, TX 77493
American Bureau of Shipping (ABS), Spring, TX 77389

Background

Ultra-deepwater oil and gas production systems routinely cost multiple billions of dollars and require multiple appraisal wells at costs in the hundred-million-dollar range (each) to justify sanction, followed by years of delayed production while designing, constructing, and installing the required facilities. According to numerous industry forecasts, a growing number of oil and gas accumulations in deepwater will be developed via long tie backs of subsea wells to existing host facilities. One of the key challenges to the success of these subsea well tie backs is to safely and reliably supply the necessary chemicals to maintain wellbore integrity and flow assurance in the long-distance flowline. 

Virtually all wells, particularly subsea wells require production chemicals to prevent and/or mitigate corrosion within the wellbore and flowline blockage from wax, paraffin, hydrate and other deposition. Onshore and offshore dry tree (platform-based production systems) well treatment is straight forward with direct (surface – platform) access to point of chemical need. For subsea wells, current technology is to deliver these chemicals via an umbilical; a complex, multi-component, wire, fiber and chemical conduit tubes bundled together and positioned across the seafloor from host platform to subsea well. The umbilical is purpose engineered for each application, has long delivery schedules and is expensive to build and install. Once installed they are prone to clogging if chemical usage is changed, as is often necessary over the life of a well. Even if the umbilical doesn’t clog or corrode over the life of the well, at abandonment they are expensive to remove and are not reusable. Even more problematic, for long offsets subsea wells, the umbilical cannot flow the required volumes of high viscosity chemicals across the significant offset distances and still have sufficient pressure to flow into high pressure subsea wells. By providing the required chemical injection local to need, subsea, the most expensive part of the umbilical, the chemical tubes can be removed, significantly reducing umbilical cost and allow much longer offsets to host platform facilities.

While individually subsea wells are usually exploiting smaller resource plays and may have less reserves when compared to the giant offshore platform developed fields, in aggregate and particularly in the Gulf of Mexico (GOM), they could represent significant reserve and production potential. They are much cheaper than dry tree wells (which require a platform) and can be developed much more quickly.

Figure 1. SolidWorks drawing of the Shuttle, Storage Tank and Process Module.
Figure 1. SolidWorks drawing of the Shuttle, Storage Tank and Process Module.
Figure 2. Test tank article
Figure 2. Test tank article
Figure 3, Bladder inside T11 Tank, bladder holds chemical.
Figure 3, Bladder inside T11 Tank, bladder holds chemical 
Fig 4.
Figure 4, Process Module 
Figure 5, Overall system with 100 BBL T11 Tank, Process Module, and Host Facility Power Regulator & Control Module (PRCM)
Figure 5, Overall system with 100 BBL T11 Tank, Process Module, and Host Facility Power Regulator & Control Module (PRCM)
Fig 6.
Figure 6, Process Module, Factory Acceptance Test (FAT) ‘dry’ and ‘wet’
Figure 7. Schematic image of the shuttle on the seafloor.
Figure 7. Graphical image of the shuttle on the seafloor.
Impact

Without the development and commercialization of the proposed technology, billions of barrels of oil equivalent could go undeveloped or unrecovered. This project will help safely develop and enhance recovery of resources from these long offset reservoirs, adding royalty revenues, jobs, and energy security, which are of particular importance in today’s unpredictable environment. Also, the additional production from subsea wells feeding a host platform may both 1) extend the potential life of the host facility and 2) generate better host facility economics by spreading host facility’s fixed cost over more barrels of through-put added from the subsea tie-back. 

The Subsea-Shuttle™ is pressure compensated and reusable over a very wide operational envelop, lending itself to commercial deployment on a rental or service ($ per gallon of chemical delivered) basis. As well conditions change with time, the unit may be recovered and redeployed with different chemical at the same well or redeployed at a new location. In additional to technical benefits, this feature provides a benefit of moving the cost from a capital expenditure (CAPEX) to an operating expense (OPEX).

Environmental, Health and Safety Benefits

Linked with the project’s enhanced oil recovery objective are important environmental, health, and safety benefits. Subsea tiebacks are much cheaper than dry tree wells, principally due to the fact they do not require a new platform and facilitate the better use of existing infrastructure . Per BOEM Acting Director Walter Cruickshank, “Using BSEE’s initial data, our team identified economic considerations specific to subsea tiebacks requiring enhanced flow assurance technologies”. By tying back a subsea well to an existing platform, an operator can avoid the cost and environmental impact of constructing a new platform, which in some instances may require in excess of a hundred thousand tons of steel. Steel production is one of the most energy-consuming and CO2 emitting industrial activities in the world. On average, 1.83 tons of CO2 is emitted for every metric ton of steel produced making steel production. While reliable sources of data could not be found, adding in the transportation of the steel to site and final fabrication of the platform, certainly increases this number. For comparison, per the US EPA typical passenger car emits 4.63 metric tons CO2E/vehicle /year . So, eliminating the need for a new platform might save the equivalent of CO2 emissions of ~ 40,000 cars over the course of a year. 

Also, the additional production from subsea wells feeding a host platform may both 1) extend the potential life of the host facility and 2) generate better host facility economics by spreading host facility’s fixed cost over more barrels of through-put added from the subsea tie-back.  

Additionally, the chemical utilized to treat subsea wells are currently stored on the deck of the platform, requiring personal protective equipment for all personnel involved with handling due to their toxic nature. Subsea Shuttle’s patented technology allows safe storage of these same chemicals subsea in a dual barrier storage tank where they can be injected at the point of need. 
 

Accomplishments (most recent listed first)
  • Stakeholder day, site meeting (2022-05-13)
    • Approximately 50 participants including representatives from BSEE met at facility and reviewed equipment and discussed forward plans
  • SSS is awarded Offshore Technology Conference (OTC) Spotlight on New Technology award.

Figure 8, OTC Spotlight award; NETL, David Cercone, Subsea Shuttle, Art Schroeder, LSPI, John Gillespie.
Figure 8, OTC Spotlight award; NETL, David Cercone, Subsea Shuttle, Art Schroeder, LSPI, John Gillespie. 
Figure 9, SSS booth at OTC, finalist for ASME award
Figure 9, SSS booth at OTC, finalist for ASME award
Figure 10, Working with US Navy, demonstrating SSS technologies (Norfolk, Va.)
Figure 10, Working with US Navy, demonstrating SSS technologies (Norfolk, Va.) 

 

Current Status

The System Integration Test plan is being finalized and will be executed over the next 2 months concluding in July 2022.  Phase 1 report will be completed and submitted to NETL for their review and pending approval permission to enter Phase II.

Project Start
Project End
DOE Contribution
  • Phase I
    Budget Period 1 – DOE Contribution: $1,049,629
    Budget Period 2 – DOE Contribution: $1,358,075
  • Phase II
    Budget Period 3 – DOE Contribution: $591,258
  • Planned Total Funding 
    DOE Contribution: $2,998,692
Performer Contribution
  • Phase I
    Budget Period 1 – Performer Contribution: $265,000
    Budget Period 2 – Performer Contribution: $1,360,000
  • Phase II
    Budget Period 3 – Performer Contribution: $612,000
  • Planned Total Funding
    Performer Contribution: $2,237,000
Contact Information

NETL – David P. Cercone (David.cercone@netl.doe.gov or 412-386-6571)
Subsea Shuttle LLC – Art Schroeder (art@SubseaShuttle.com or 713-681-1482) 

Additional Information

Energy Tech Venture Forum XVIII 2020 Presentation Rice Alliance for Technology and Entrepreneurship [PDF], September 2020

Subsea Shuttle Subsea Chemical Storage Unit 2020 06 08 Draft 7 [Youtube], June 2020