Success Story: A Cost Effective and Systematic Approach to Restore Integrity in Wells Having Sustained Annulus Pressure Using Rigless Intervention

Abstract

Objectives/ Scope

Multiple wells were diagnosed to be suffering from sustained annulus pressure due to packer failure. As a result, they are categorized as having high-medium risk (CAT-2/CAT-1), which require intervention. To restore such problem in a cost-effective manner, a systematic rigless approach of Annulus Cementing using Composite Plug has been successfully used to restore the integrity of the wells. At the same time, this method enables the wells to be put back into production or injection. This paper describes multiple success stories which ultimately has extended the well life and avoided expensive rig workovers.

Methods, Procedures, Process

To reinstate the packer integrity, the well is killed with brine and a millable composite plug is set in the tubing between 30-40ft above the packer followed by tubing punch to create circulation into the A annulus. A carefully calculated volume of cement, to create 200-300ft of barrier, is displaced using Coiled Tubing into the A annulus. Cement over displacement technique is used to create shorter cement height to mill in the tubing. Upon confirmation of good pressure test in the A annulus and the tubing, the cement and composite plug are milled enabling production or injection to resume. All operations are performed rigless using well intervention barge.

Results, Observations, Conclusions

More than five wells have been secured and put back to operation following this method. The wells have been observed for more than one year with integral annulus. Various lessons learned to perform the annulus cementing and composite plug milling have been registered and will be discussed in detail in this paper. These lessons have reduced the overall well securing time by half. The success of these rigless annulus cementing have led to:

• A minimum saving of $5 million in avoiding rig workover and allocating the rig time for more productive work.
• Reduce well securing time from 45 days (with Rig) to 21 days (rigless) leading to reduction of carbon footprint by 1000 Tons of CO2 per well.

The approach of annulus cementing, and the valuable lessons learned captured during the operations will help the well intervention community to execute the same jobs in a shorter duration saving time and money with reduced carbon footprint.