9 1/2″ WELLTEC® ANNULAR BARRIERS ENABLE HIGH PRESSURE, CEMENTLESS, ZONAL ACID STIMULATION

Welltec Annular Barrier for COMPLETIONS SOLUTIONS

Background

In the North Sea an operator needed to deploy a liner across an 8,000 ft horizontal section within a selected reservoir comprised of eight zones. The challenges were that the zones had to be completely compartmentalized (isolated) from each other and able to withhold up to 8,000 psi Delta P during an extensive acid stimulation job as well as isolate a nearby, water-bearing zone.

To improve economics and maximize reservoir exposure to the acid, cement was avoided as part of this solution. The baseline operation was built up from an extensive drilling and production data base and with this novel completion the well was projected to deliver 2,900 barrels/day.

OPERATION

After an extensive engineering study, sixteen wellbore annular barriers (WABs), were installed on the operators line assembly and deployed in the well, sealing off the selected eight zones. Once the entire liner / WABTM assembly reached the desired TD, pressure inside the liner was increased to a pre-engineered level and subsequently all WAB’s were expanded as designed in less than 30 min.

With the zones completely isolated, an acid stimulation job took place and the desired maximum Delta P up to 6,000 psi was achieved between each zones. The pressure was successfully contained within each zone while the stimulation job went from one zone to the other as designed. The zonal compartmentalization and WABTM integrity were confirmed by temperature and pressure sensors located within each of the zones using independent readings.

ACHIEVEMENTS

Eliminating the need for cement in this project, lowered the CAPEX and enabled the operator to achieve the desired, extended reach drilling target while overcoming the limiting ECD concerns.

COMPLETE ZONAL ISOLATION
IMPROVED STIMULATION
PRODUCTIVITY ACHIEVEMENT (PLANNED
2,900 BUT AFTER SIX MONTHS OF PRODUCTION
ACHIEVED AN AVERAGE OF 4,500 BBL/
DAY WITH ONLY 2% WATER-CUT)

 

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Eliminating the need for cement in this project, lowered the CAPEX and enabled the operator to achieve the desired, extended reach drilling target while overcoming the limiting ECD concerns.