Metal Expandable Packer Isolating Shallow Water Aquifers on a Middle East Appraisal Well

During the planning phase of an offshore exploration well, Eni Abu Dhabi BV (Eni) had recognized the challenge of isolating shallow water aquifers across a 16″ drilled hole section, using a single stage 13-3/8″ cement sequence. Through a multi-team approach, a combination of first-stage cement, a Metal Expandable Packer (MEP) and a contingency second stage-cement operation was identified as a solution to positively seal the C annulus and prevent Sustained Casing Pressure (SCP). The well was drilled using a 16″ bit across the shallow UER and Simsima aquifers. From regional experience, cementing challenges were clearly understood. These formations are notoriously difficult to achieve a cement only seal, this seal providing the Well Barrier Element (WBE), as defined by regulatory guidelines. When cementing, the slurry can be impacted by a combination of water contamination and potential cement losses due to a combination of Equivalent Circulating Density (ECD), low fracture gradient, pore pressure, and formation permeability. To address these challenges, the 13-3/8″ casing included an MEP and a second stage contingency Port Collar, both positioned shallow of the planned primary stage Top of Cement (TOC). This solution provided an effective single-stage MEP and cement combination to address the risk of SCP and negate the need for implementation of a second-stage cement operation or bringing cement to surface. This was the first deployment of the MEP within the C annulus in the Middle East region. The combination of cement and MEP technology to address and eliminate the risk of SCP has many applications through the region, reducing risk, cost, rig time, and methane emissions.