The Relief Well Injection Spool (RWIS)

Add Energy and Trendsetter Engineering have combined expertise to provide market leading engineering and hardware to optimize well design and assure single relief well contingency.

RWIS Photo

The Relief Well Injection Spool (RWIS) is a patented specialist subsea equipment that enables operators to stop a blowout from prolific reservoirs safely and efficiently via a single relief well. This is made possible with the RWIS by increasing the pump rate of kill mud into the blowing well by removing the bottle-neck caused by restrictive choke and kill lines from the surface vessel to the seabed.

The RWIS has been designed and built to significantly increase the pumping capacity of a single relief well by pumping in excess of 200 barrels of kill mud per minute through a single relief well, four times as much kill fluid as typically achievable. A significant advance for the industry which utilizes multiple vessels as opposed to the alternative method requiring multiple relief wells.

In addition to the RWIS assuring single relief well contingency, the RWIS also enables operators to optimize well economics and help unlock projects that wouldn’t normally be sanctioned. In purchasing access rights to the RWIS, operators are able to comply with legislation and reduce the number of wells required to meet production targets by increasing the completion size of the well bore, reducing CAPEX costs and maximizing production.

Benefits of using the RWIS:

Watch the RWIS in Action

Project Development:

When the unthinkable happens:

Click here to Contact our RWIS Experts

Click here to view the specifications sheet.


Add Energy was approached by a client who, according to company safety guidelines, requested a blowout-contingency study for an offshore shallow gas well.

A blowout intervention for these types of wells are often faced with many challenges including a narrow depth window to build hydrostatic and frictional pressure during a dynamic kill combined with high pressure differential to balance the reservoir pressure. For a worst-case blowout scenario, using a relief well injection spool (RWIS) may ensure the ability to bring such wells under control with a single relief well.


The Add Energy well-control and flow-simulation specialist modeled the worst-case-blowout scenario using the planned wellbore schematic and predicted reservoir properties. A single relief well with an RWIS installed on its wellhead was used in the simulations to pump kill mud into the target wellbore. Several iterations were made using different kill muds and hardware configurations to achieve a successful kill.


A worst-case gas discharge of around

3 Billion SCF/Day

A dynamic kill using the RWIS to pump a heavy mud at a combined rate of

230 bpm

50 bpm down primary relief well and 180 bpm down secondary relief well connected to the RWIS
Hardware configuration was evaluated for hhp requirements, pump curves, pressure ratings, erosional velocities, fatigue limitations, system redundancy and other constraints
The study demonstrated that a prolific worst-case blowout scenario could in this case be killed with a single relief well.