Well integrity is critical in the petroleum industry, and needs to be maintained throughout the entire well's life cycle. Cement is the main element that provides isolation and protection for the well. To provide an additional protection beside the cement, mechanical isolation packers can be utilized to mitigate the chance of having fluid communication to the surface. Pressure buildup prevention in the casing/casing annulus remains a challenge in High pressure, high temperature (HPHT) offshore gas wells in the Arabian Gulf due to the presence of shallow gas, abnormal pressure formations, and highly fractured loss zones, which makes all cement jobs critical to isolate the well properly. This paper will discuss the preventive methods put in place to avoid casing-casing annulus (CCA) pressure buildup and sustain well integrity. Cementing strategies and mechanical isolation packers were considered to ensure the presence of competent barriers to prevent fluid bypass to surface. With regard to cement strategies, some methods will be discusses such as use of resin-based cement, which enhance the shear bond and mechanical properties to prevent cement cracking. For the mechanical barriers, conventional staging tools in the 9-5/8-in. production casing will be replaced with high differential pressure liner hanger packers and will be tied and cemented to surface to ensure maximum sustainability. In the future, they will be replaced with HPHT cement staging tools with a packer that is gas-tight to decrease the operating time while having the same reliability. In addition, a lab tested casing joint with elastomers that can swell in any fluid medium are considered to provide isolation in case the casing-cement bond failed at a later stage. Having a locked potential well due to CCA will increase the operation cost by early workover, in addition to losing the production. Enhancing cement strategies and utilizing mechanical isolation packers will help with preventing pressure build-up in the CCA and maintaining well integrity for the entire well life cycle.

The current practices to monitor Tubing-Casing Annulus (TCA) integrity involves applying a sustained pressure with inhibited fluid in the annulus space. This is to allow for a positive indication of pipe integrity. In such cases where integrity is lost, it is challenging to diagnose or pinpoint the exact leak source. Because of the current limitations in the assessment procedures, inaccurate diagnostics can result, which can lead to expensive and time consuming operations and deferred production. Well-A is a single string well drilled as a vertical oil producer. The well has undergone several workover operations and was recompleted as a single string observer many years ago. After being healthy for a long period, it was reported in recently that this well was suffering loss of TCA integrity. In addition, the tubing was reported to have an obstruction above the packer, and the master valve was in a partial stuck-open position. Since diagnosing downhole problems will allow for a safe, optimized and long lasting remedy job, it was decided to run High Precision Temperature (HPT) and Spectral Noise Logging (SNL), to assess the integrity of the TCA, and identify the source of the leak. The investigation was carried out rig-less, prior to moving the rig, to reduce time and optimize cost. The results showed that the loss of TCA integrity was due to a casing leak, and confirmed the packer and seals integrity. This useful information eliminated the necessity of securing the reservoir below the packer, reducing costs and saving one week of rig time. In addition, proving that no communication existed between the reservoir and the TCA prevented sidetracking the well, which would have resulted in incurring a significant cost and about 1.5 weeks of rig time.