Technology Streams to Deliver Rigless P&A


The Oil and Gas Authority has challenged industry to reduce overall UKCS decommissioning by over 35% from the 2017 baseline estimate. Well P&A is estimated to account for circa 45% of the total basin decommissioning cost estimate, however, analysis of industry data indicates that the cost of decommissioning both platform and subsea wells has remained stubbornly stable.

Technology Streams

Rigless P&A

There are a number of intervention phases during well decommissioning whether conventional or rigless:-

  • Securing access in the well to the desired barrier setting depth
  • Evaluation of existing barriers elements either for inclusion in barrier design or to identify remediation
  • Conditioning of the well architecture to accept barrier placement or remediation of the failed barrier elements
  • Placement of barrier materials
  • Verification of Isolation barriers as a whole and/or individual barrier elements

Alternative Barrier Materials

Alternative materials used solely or in composite barriers have potential to provide more reliable and resistant isolation compared to Portland cement.

Barrier element solutions that can delivered through tubing as an alternative to pumping conventional cement plugs for abandonment, intermediate and environmental barriers open up the possibility of rigless abandonment and potential cost reduction and Net Zero benefits.

Enabling Intervention Technologies

There will be occasions where prevailing well conditions necessitate some preparation and conditioning of the existing comepletion or remediation of compromised barrier elements. Enabling technologies provide through tubing services to perform a wide range of tasks to support barrier placement.

Established wireline, tractor, or coil intervention techniques may be required to ensure access (e.g. mill scale, remove debris or recover fish) or set plugs to act as a platform to support barrier materials, while speciality tools are emerging on the market to support P&A activities e.g. recovery of control and service lines, to cut a window or perforate tubing to place an annulus barrier, break down annular cement to remediate a failed barrier.

Through Tubing Evaluation & Verification

Reliable barrier design and construction relies on assessment of the integrity of the existing well construction e.g. location of annular cement and bond quality. Through tubing evaluation allows for this to be completed in advance of the abandonment programme and by avoiding the need to recover tubing opens up the potential for rigless well decommissioning utilising alternative barrier materials.

Through tubing verification of barrier performance provides the opportunity for full rigless abandonment. Through tubing cement evaluation can also play a key role in assessing the ability of legacy wells to meet the containment criteria for Carbon Capture and Storage projects in depleted oil and gas fields or subsurface Hydrogen storage projects.