Deploying Different Proactive Strategies for De-Risking and Arresting Wellhead Gas External Leaks in High-Risk SAP B Well: A Case for Reliable Well Integrity Management
Authors: Darwish A. M. , Alkaabi S. A. , Al Hammadi M.M. , Alkasar S. M. , Khalaf M. A. , Hasanov A. , Piccone G. G. 
Published: November 2024

Mitigating the risk in wells operating with sustainable annulus pressure (SAP) is vital to safeguard the operation against loss of pressure containment in the manner of hydrocarbon release to the surface, cross flow between reservoirs, and/or supercharging shallower formations and aquifers. This paper describes several methodological approaches that were implemented to control a problematic SAP well which had wellhead external leak, located in the proximity of living quarters, and communicated with a shallow pressurized formation.

The integrity jeopardizes when the SAP is developed by external source which feeds the annulus unceasingly with hydrocarbons to exceed the maximum allowable annulus surface pressure (MAASP). In such circumstances, casing-to-casing SAP B wells can be more serious than tubing-to-casing SAP A wells. Since, any failure at one weakest element of the secondary barrier envelope can cause immediate gas release. The presented case is an oil well handed over to operation with poor cement coverage under dispensation and risk assessment since it is not complying with integrity standards. During well barriers evaluation and commissioning, SAP B problem was investigated and analyzed with a pressure greater than the MAASP sourced by a direct communication from a supercharged formation. Well's integrity compromised due to cement impairment and defected casing housing connections resulted in minor gas flow directly to the surface.

Proactively, the well area was familiar since it has investigated previously and identified as hazardous area because of the existence of supercharged shallow formation and its close distance to accommodation. That's why a resilient annulus pressure monitoring plan was set to capture any anomalies and it succeeded in revealing the well's integrity issue in a timely manner. The risk was evaluated to be high, and mitigations considered by conducting extended bleed off and flaring procedure to maintain the SAP B within the safe operating envelope. Additional precautions were engaged to shut-in all nearby injectors for certain duration which might be correlated to the well SAP B behavior. The leak problem was tackled by different strategies. A quick welding commenced firstly after the top-up cement job and followed by a composite wrapping operation which eliminated the leak. As a result, the well is secured with guaranteed safe condition for rig mobilization. The rig entry remediated SAP B through both conventional section milling intervals with cement squeeze and new archer technology then tie backing. Furthermore, rectifying the leak at surface by welding, wellhead sleeving, and pressure testing.

The implemented practice shed light on different techniques which can be fast tracked in comparable cases to enhance the decision-making process shortly. It emphasized the well integrity reliability management, obtained safer operation with high durability, and contained the fluid to prevent upmost sever consequences.