SANJEL ENERGY REDUCES THE FREQUENCY OF SURFACE CASING VENT FLOWS IN THE BC MONTNEY BY 30 PERCENT

Challenges

Due to the geological makeup of the Montney and corresponding shallower formations, wells here are prone to Surface Casing Vent Flows (SCVFs) — gas leaking and migrating to surface. This is especially true in the liquids-rich, high pressured window in British Columbia, where the presence of a significant proportion of natural gas liquids and oil can result in improved economics. The high pressures that exist in this window can also result in more SCVFs requiring repairs as severe leaks need immediate attention, and all repairs reduce the overall return on investment.

Finding the source of these leaks is difficult and remedial repairs are often costly with poor success rates requiring multiple repair attempts. The leaks are often a result of pressurized formations combined with drilling and cementing issues such as poor standoff, low displacement efficiency or lost circulation.

Solutions

Sanjel Energy deploys its proprietary EXPANDOmix PRO in many sections of the Montney to reduce or eliminate vent flows. EXPANDOmix PRO has a short critical interval between acting as a liquid and transmitting hydrostatic pressure on gas producing formations and hydrating to a resulting rigidly-gelled mix which withstands any gas flow through the setting cement.

Additional features of EXPANDOmix PRO include:

  • Low fluid loss and free water prevent gas intrusion into the liquid slurry
  • High solids ratio lowers permeability to prevent gas flow through hardened cement
  • Promotes expansion once the cement cures, improving the seal between the casing, cement and the rock face
  • Flexible when stressed — deforms before failing
  • Withstands the harsh stresses from multi-stage fracturing

Results

  • Reduced SCVFs by 30 percent before fracturing operations
  • Reduced SCVFs caused by fracturing operations from 8.5 percent to 0 percent
  • Experienced exceptional cement returns to surface 100 percent of the time
  • Less remedial issues, reduced time and resources resulting in significant cost savings
  • Localized success: Over twenty wells with new products and procedures in BC Montney for this specific case study