On a four well pad, an operator drilled the intermediate section of the first well and experienced significant non-productive time (NPT) due to large mud losses in the depleted Mission Canyon Sand. Drilling fluid losses were experienced while running intermediate casing and during the cementing process, leading to two-stage cement jobs. Also, the CBL indicated cement did not cover the Dakota Sand, requiring remedial work to satisfy North Dakota’s requirement to place sufficient cement to cover the Dakota Sand.
STAR SHIELD was initiated (6 lb/bbl) in the active system 500 feet above the depleted Mission Canyon on the second well on the pad. Hourly treatments were initiated while drilling the depleted Mission Canyon and STAR SHIELD concentration was increased to 8 lb/bbl throughout the interval with no losses to the formation. CBL logs indicated sufficient cement across the Dakota Sands satisfying the state’s requirements.
The operator drilled intermediate section, through the depleted Mission Canyon with no losses and no wellbore instability issues. Intermediate casing was set with with full returns. A single-stage cement job was performed with full returns and the operator achieved a successful CBL across the Dakota Sand.
STAR SHIELD was adopted on the next two wells with same positive results.