The WelltecAnnular Barrier is a unique, all metal expandable barrier with a large expansion ratio and high delta P capability. It can be used to prevent flow between casings or between casing and open hole to provide cement assurance, to prevent build-up of surface annular pressure or to create compartmentalization within the reservoir or isolation between reservoirs.
For the test, a 9 5/8″ version of the WAB was expanded into a 13 3/8″ casing within a test cell. There it was exposed to pressured nitrogen while undergoing axial loads and temperature cycles without experiencing any leaks. Witnessed by a number of representatives from global operators as well as Welltec staff and management, the test was successfully completed in accordance with ISO/API standards.
“This qualification is the next significant step in a series of successes for the WAB,” says Paul Hazel, VP of Well Completions. “These have included being incorporated as part of the primary well barrier and being installed for zonal isolation in wells capitalizing on cementless completions.”
Ricardo Reves Vasques, VP Engineering, states “Of course the testing wasn’t easy. It has taken almost three years of research, but we’ve always believed that this technology could achieve this high standard and we wouldn’t give up until we had accomplished it.”
Welltec is the largest provider of tractor technology for conveyance solutions as well as the foremost supplier of milling, clean-out and mechanical solutions for e-line interventions. Our novel, expandable metal annular barrier’s (WAB’s) capabilities have been accelerating for the past four years and comprise the foundation of the Flex-Wellcompletion concept.
FIRST WELLTEC ANNULAR BARRIER RUN AS PRIMARY WELL BARRIER, PREVENTING SAP
BACKGROUND
The annulus between the 9-5/8” and the 13-3/8” casing strings within a Norwegian field development had historically exhibited pressure buildup at surface on many wells. It had been determined that the source of the pressure was a gas charged formation just below the 13-3/8” shoe. Obviously, for the operator, eliminating surface annular pressure (SAP) was a priority along with easy barrier verification over the lifetime of the well. To eliminate the SAP several methods had been trialled over the years including single stage cementing, second stage cementing, external casing packers and liner tie back solutions. All of these solutions had failed to resolve the problem. Meanwhile, the Welltec? Annular Barrier, WAB, had been successfully deployed by the operator for zonal isolation in a number of wells across various reservoir sections. Subsequently, it was proposed by Welltec? as a possible, alternative solution to eliminate the SAP.
In order to be utilized as a primary well barrier, replacing cement, the solution had to pass a number of significant criteria. It was carefully reviewed by the operator’s Well Integrity team to ensure that the system complied with their own company standards and the Norsok D10 guidelines. Meanwhile, further qualification of the intended solution, a 12-1/4” WAB?, was completed to extend its certifications from the ISO 14310 V3 standard to V0.
OPERATION
Prior to the installation, modeling on the impact to ECD during cementing was evaluated. The WAB? is designed to be relatively transparent to cementing operations; it has a small OD, runs slick and is rugged enough to be rotated with low torque and drag effects. The modeling confirmed there was minimal risk to the primary cement job associated with the inclusion of the WAB?. The 12-1/4” WAB? was run in the well as part of the 9-5/8” casing string to a depth of 5,210 ft (1,588 m). This placed the WAB? close to the shoe of the 13- 3/8” casing.
The primary cement operation focused on establishing good cement around the shoe of the 9-5/8” and cement quality was ensured by keeping the cement top deep within the 12-1/4” hole. Once the cementing operation was completed, the cement dart was bumped and additional pressure applied from surface to expand the WAB?. The well was pressurized in steps up to 5,072 psi (345 bar), which hydraulically expanded the WAB? without compromising the casing integrity.
Verification of the WAB? as the primary barrier was achieved via application of surface pressure down the 13-3/8” x 9-5/8” annulus; pressure equivalent to the fracture gradient of the formation below the 13-3/8” shoe plus a 1,030 psi (70 bar) surplus. The pressure was held for 10 minutes to confirm isolation and verify the barrier.
ACHIEVEMENTS
This installation marks the first time that something other than cement has been installed in a well completion as a primary barrier. Based on the testing and qualification accomplished, the operator was able to install the WAB? as a primary barrier without the need for a dispensation from the authorities. Since this first operation, a further two wells have been completed and a fourth well is in planning for the client.
FIRST WELLTEC? ANNULAR BARRIER DEPLOYED THROUGH A SIDETRACK WINDOW FOR CEMENT ASSURANCE
BACKGROUND
Severe deposit build-up caused an existing well to lose production within days of being brought online. Subsequent efforts to remove the scale were successful but unfortunately it returned immediately after placing the well back online, again cutting off production. It was concluded by the operator that the scale was originating from a formation above the producing zone and channeling down.
The well was side-tracked in order to avoid the scale producing formation. Unfortunately, cementing across this zone to isolate the solutes from migrating into the production zone was seen as a challenge due to the formation properties.
The operator decided to incorporate the Welltec? Annular Barrier (WAB?) as a solution to provide integrity and remove potential cement channels. The strategy employed was to annularly isolate the problematic formation from the production zone using a combination of cement and WAB’s. The WAB’s would be expanded in the green cement to ensure isolation where required. This was the first deployment of WABs in a highly deviated environment through a sidetrack window.
Initially, three WAB’s were mobilized with a plan to stack the barriers below the sections where the scale producing formation was thought to be encountered. After the 12 1/4″ section was drilled to total depth it was determined that only two WAB’s would be required to provide isolation.
The first WAB? was successfully installed with the top at 10,273 ft (3,131.18 m) MD; the second at 10,199 ft (3,108.65 m) MD. Both WAB’s were set after the cementing operation by applying pressure to the 10 3/4” x 9 5/8″ casing string.
ACHIEVEMENTS
The WAB’s, designed to independently isolate the formation in the case of poor cement, provided a complimentary solution with the cement in this application. This solution provided additional confidence for the required isolation and did so without any reduction to the ID of the production string.
The well has been returned to production without the previous scaling issues reoccurring, thus verifying the two-part cement / WAB? solution and providing the operator more reliable production.
The WAB provided a solution that, because of its rugged construction and low upset OD, could pass through the sidetrack window. Utilized in conjunction with cement the risk of having to re-drill the well or sidetrack again due to poor cement was eliminated. Delivered within a tight timeframe, the operator was very satisfied with the execution and results.
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