Surface Intervention System – SIS


Unity’s Surface Intervention System is the industry’s first multi-functional shallow well intervention solution. As a rigless conveyance system it delivers significant operational efficiencies, a reduced wellsite footprint, a reduced personnel requirement and cost savings of up to 75% for a single deployment.

This mobile, self-contained solution can be used across a variety of operations including well inspection, shallow plug setting, frac sleeve installation, milling, well-bore clean out and Xmas tree removal. Consecutive tasks can be performed at the wellsite, with only two people required to operate the system.

The technology is field proven and has built a strong track record. In its first deployment, the Surface Intervention System was mobilised off the coast of Tunisia for a major operator to set two frac sleeves on two wells. Each sleeve was successfully set in under three hours, including rig-up and down time – significantly faster than the c.24-hour schedule for traditional intervention.

Wireline or coiled tubing intervention often requires multiple vendors with considerable manpower and a large wellsite footprint, increasing risk for the operator. While this equipment is necessary for deeper well intervention, the Surface Intervention System provides an efficient alternative solution for shallow operations.

The Surface Intervention System is compatible with industry standard, interchangeable tools. This enables simple switching between functions at the wellsite. It can operate at wellbore pressures up to 10,000psi and has a powerful hydraulic motor with a push, pull, rotate and vibrate function to rival wireline or coiled tubing capability.

Its compact dimensions of 660mm wide x 3455mm high, with a weight of only 1,060kg, delivers a small wellsite footprint and means the technology is eminently suitable for shipping to any location around the world.

Decommissioning Efficiency

Our versatile Surface Intervention System is not just for production optimisation and well integrity applications, it can also be used to significantly improve the efficiency of wellhead decommissioning.

As an offline, rigless, conveyance system with its own integral well barriers, the Surface Intervention System can quickly inspect the well, set plugs and remove the Xmas tree in a single deployment. It acts as an innovative ‘elephant’s foot’ tree jack, with powerful lift and vibrate functions, suited to the safe removal of end of life, corroded or compromised equipment.


The UK Oil and Gas Authority’s ‘Wells Insight Report 2018’ cites that well integrity problems were the single biggest cause of production losses in the UKCS, accounting for 43% of the total 33 million BOE loss, of which 10 million BOE (c.30%) was due to wellhead, Xmas tree and annulus failures.

There is a clear opportunity for new technology to help mitigate these issues and safeguard the integrity of ageing wells, whilst reducing intervention time, cost, risk and overall operational footprint.


Surface Intervention System applications include:

  • Well inspection using video camera, memory caliper or drift gauge etc
  • Plug setting and retrieval
  • Installation of protective sleeves inside the Xmas tree to improve its integrity and facilitate high pressure operations such as fracking, cementing, chemical or other injection treatments without the need to upgrade the Xmas tree.
  • Milling, for example through tough, tungsten carbide faced, stuck or inoperable gate valves and other wellhead blockages, up to 7” in diameter using a custom range of bits.
  • Cleanout tools deliver multiple functions including scraping, brushing, water jetting and debris removal. A fluid injection system cools and lubricates whilst clearing debris, eliminating the need for external lubricators.
  • Tree jack – once well barriers/ plugs have been set, the device can remove the Xmas tree for repair, upgrade, recertification or replacement.

For more information on our latest Surface Intervention System projects and product news please visit our LinkedIn page.