Large sections of reactive shale between the pay zones pose an additional threat. Water-based fluids can cause shale to quickly swell, deteriorate, or both, resulting in an unstable wellbore that can collapse and prevent a complete gravel pack. Water-induced spalling—or breaking up—of the shale can also cause premature screenout, impair pack porosity and permeability, or plug the screen. Incomplete placement of the gravel pack has undesirable consequences, ranging from higher completion costs to erosion hot spots, sand in surface facilities, and long-term completion reliability issues.

Integrated system enhanced efficiency and reduced cost and risk

Schlumberger used a comprehensive approach to gravel packing to achieve a successful outcome. OptiPac Alternate Path openhole gravel-pack screens provided a redundant mechanism with shunt tubes and nozzles that enabled slurry to bypass bridges and resume packing downstream of the bridge, progressively packing toward the toe. The screens were used with a nondamaging carrier fluid, state-of-the-art modeling software, and a customized pumping design.

The viscous ClearPAC XD fluid was used to carry high concentrations of gravel. This fluid is a water-based system composed of a viscoelastic surfactant (VES) and a completion brine. It exhibits low friction pressure during pumping, making it ideal for gravel packing long horizontal intervals with Alternate Path technology. Higher gravel concentrations in a viscous carrier fluid meant that the job could be pumped quickly and with relatively small fluid volumes, a significant advantage for deepwater operations, where both time and space are at a premium.

Nondamaging K240 shale stabilizer was added to the gravel-pack fluid to reduce the spalling risks associated with exposed reactive shales in the openhole intervals.

FIV-II formation isolation valves minimized loss of completion fluids. The valves were compatible with the operator's upper completion design and allowed one-time interventionless opening using pressure cycles (instead of downhole mechanical intervention), saving further rig time.

Operator completed 27 wells with 100% annular packing

Designed for endurance and efficiency, the DeepSTIM II stimulation vessel enabled quick deployment of reliable equipment and experienced personnel to the remote deepwater locations. Blending and pumping systems on board handled the gravel-pack fluid while continuous monitoring and control of critical parameters provided the highest degree of quality assurance. Twenty-seven wells were gravel packed with 100% success and are producing sand free. The complete annular packs extend completion life and together with the low skin, improve production and recovery.