Extending Well Life and Securing Well Integrity Efficiently
Authors: Hurtado Noe , Zapata Fernando , Alzaabi Ahmed , BinKalban Mohamed , Karmstaji Mohamed , Roicki Krzysztof. 
Published: November 2024

Well integrity is one of the most critical aspects during the life of every gas or oil well. Safety of production or drilling personnel cannot be neglected. To mitigate, damaged downhole equipment or well integrity needs to be monitored controlled, inspected and if necessary repaired or upgraded. It is common to see wells being suspended or abandoned when Sustained Annulus Pressure (SAP) appears either in A, B or C annulus. To rescue these wells, we need to cure any well integrity or safety anomalies to either preserve the asset or responsibly retire the asset.

In this case study well salvage operations were focused on curing SAP-A due to packer/tubing/csg anomalies and SAP-B that was present between 9-5/8″ and 13-3/8″ annuli. For this well, it was essential to first successfully cure SAP-B first, to be able to proceed to address SAP A with the completion replacement, resulting ultimately in SAP-B curing effectiveness being predominant to meeting well integrity objectives and putting well back to production safely and efficiently. A sustainable and safe approach was selected for curing SAP-B – Perf, Wash & Cement (PWC). This efficient technique has been getting more attention globally as an effective way of curing SAP and has several significant advantages over the traditional approaches (section milling, perf & squeeze, csg patch, etc).

The well was scheduled for intervention to cure two sections with SAP B and if successful, repair SAP-A, conditions were challenging but worth given the productivity of the asset. The well was rescued and successfully producing, recovering over approximately 150% of the cost and saving over 80% of the typical cost of the interventions, replacement, and additional P&A cost for decommissioning.

During workover a reliable retrievable bridge plug with a special design has been selected to serve as a base for the treatment, thus eliminating any debris left in the well after workover, saving rig time and avoiding accessibility and re-completion concerns with the debris left on top or inside the liner. Moreover, a mechanical perforator allowed to safely and efficiently perforate 150ft interval without use of any explosives and a closed-loop system was utilized for effective washing and cementing the selected intervals. After successful displacement of cement into perforations and sufficient WOC time, the treated interval has been drilled out and RBP retrieved without any difficulties. The second stage allowed to reposition the tool in a shallower interval to address a second area of concern curing SAP-B. After operations were concluded, SAP-B was reported as 0psi thus allowing the Operator to install 7″ Tieback casing cemented in place, thus allowing to run new completion string and curing SAP-A.

After confirming and identifying the concerning SAP A and B sections. An analysis of several methods and options was carried out and it was decided to select a very safe and efficient methodology to address the well.

This system allowed for very safe, efficient and time saving casing mechanical perforation while enhancing the washing and removal of the debris and solids found behind the casing and at the same time it was able to preserve the integrity of the casing behind. The tool was run to repair two sections in a single run saving approximately 15% of the total cost for a regular intervention and 4 days rig time.