Resources

OVERVIEW

Located in Western Alberta, there is a resource-rich play sought after by many E&P (explorer and producer) companies. Formations such as the Cardium, Wilrich, Duvernay,
Falher, Rock Creek and more are being targeted for their liquids-rich-gas production. One prominent E&P encountered challenges with obtaining cement returns to surface on their Intermediate casing string. Cement returns to surface are required to ensure proper zonal
isolation and failure to do so poses HSE risks and potential remediation costs

CHALLENGE

An operator had several wells of which lightweight drilling fluids were needed to effectively drill the intermediate portion of the wellbore down to about 1900m (6234ft) TVD. Lightweight drilling fluids of 900 kg/m3 (7.5 ppg) were required to achieve fluid returns to surface. For cementing their intermediate casings strings, cement slurry densities of about 1100 kg/m3 (9.2 ppg) were used in an effort to get cement returns to surface. During mixing and displacement, ECD’s exceeded the frac gradient of the Belly River formation preventing these slurries from achieving cement returns to surface. Different process, procedures and technologies were attempted resulting in little improvement.

SOLUTION

Magnum was provided with an opportunity to work the operator and set out to understand the previous successes, failures, and challenges encountered with drilling the wells.  Technologies, procedures, and simulations were thoroughly discussed and evaluated to identify the proper solution for cementing the intermediate casing strings.

• An advanced lightweight preflush was designed at 900 kg/m3 (7.5 ppg) to provide drilling fluid displacement, filtercake removal and water wetting properties
  to properly prepare the well for cement.
• A proprietary highly reactive lightweight cement blend of 900 kg/m3 (7.5 ppg) was used to maintain low ECD’s allowing full cement returns to surface. This
  design provided the required properties needed for zonal isolation and provided a
  quick transition time preventing fall back and maintaining a cement-filled annulus.
• Specialty additives further complimented the overall design by providing proper pump time, viscosity, ductility, and bond enhancement characteristics needed to for well life support..
• Accurate and reliable cementing equipment provided all pumping operations to be completed within the designated density control and pumping rate limits. This ensured the cement blend performed as designed throughout the entire wellbore.

RESULTS

Preflush and cement returns to surface were achieved by providing proper drilling fluid displacement cement slurry design. Zonal isolation throughout the Intermediate casing string was provided utilizing proprietary technology consisting of; proper density, rheology, and yield point design of the preflushes as well as ultra-lightweight lead slurry combined with proper operational practices to achieve fluid returns to surface.