Technical Paper
Technical Paper

Reduced Risk in Plugging and Abandoning (P&A) on the UKCS

Written by: Alexander Edwards, Sam Green and Jakob Heller of Ikon Science

Reducing risk by inclusion of robust subsurface analysis for plugging and abandonment campaigns: Well abandonment is driven by economic decisions, namely when unit lifting costs are no longer profitable. Generally, governmental authorities require that well operators perform safe and environmentally compliant abandonment operations by establishing a permanent barrier to retain remaining hydrocarbons in their existing reservoirs and prevent the release of hydrocarbons to the surface. However, the regulator guidelines do not always articulate how these processes should be implemented, and it is therefore at the discretion of the operator to decide which, and how, processes are put into place. This in turn leads to an inconsistent response with little opportunity to share best practice and drive overall operational and cost efficiency. Therefore, there is a significant risk of failure to deliver a successful well abandonment due to the lack of standardization and experience.

Traditional Plugging and Abandonment (P&A) methods (a major component of decommissioning and restoration activity/risk exposure/cost) are often time consuming, costly, and have remained largely unchanged despite significant technological advances in the industry in other areas of the exploration and production supply chain. Approaches by operators to P&A procedures are currently disaggregated both, technically and commercially, which results in: higher risks, higher costs, sub-optimal operational performance and lack of improvement by learnings. A way forward would be to develop a risk-based verification service to drive a safe, efficient and affordable P&A process founded on a high quality risk assessment matrix (RAM). A common platform/framework is needed to describe what needs to be verified and how, based on best practice in pore pressure and geomechanical prediction, risks can be quantified and managed to an acceptable level.

To help improve the process we present a way to re-think the plugging and abandonment design plan based on the geology, which controls the distribution of fluids and pressures, hence guiding the placement and number of well plugs.

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