North Sea Operator Cures Lost Circulation While Cementing in Weak Formation

Cement well in formation with known lost circulation issues

An operator was completing the initial development phase in the North Sea with six horizontal oil wells and eight water injection wells. While drilling and cementing the injector wells, the operator encountered severe lost circulation issues. Only one out of seven cementing jobs in the 12 ¼-in section was executed with full returns.

Adding to the challenge, the operator needed to set the casing of an upcoming injector well into depleted sandstone to provide adequate pressure support to the target area. This reduced the fracture gradient considerably. The operator needed to control fluid losses and ensure successful cement placement around the shoe to avoid water injection into the undesired formation.

Use engineered fiber technologies to plug thief zones

Reviewing the data from previous operations in the field revealed that losses were present while running casing, prior to cementing operations. To optimize mud removal and ECD management in the narrow window between the fracture gradient and pore-pressure gradient, Schlumberger ran simulations of different fluids and lost circulation material (LCM) using CEMENTICS zonal isolation software. The team recommended adding Losseal Microfracture lost circulation control treatment into the spacer and CemNET advanced loss-control fiber technology into the cement slurry. In collaboration with M-I SWACO, a Schlumberger company, the cementing team also proposed pumping WARP advanced fluids technology with treated micronized weighting agents to help  deliver lower ECD values.