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While drilling through the Eagle Ford shale, operators often experience a large amount of gas requiring higher mud weights. Operators typically have to increase the mud weight (in this case to 13.5 lb/gal) in the troublesome Wilcox interval. While placing a mud cap, one operator experienced lost circulation, breaking down the Wilcox formation. Significant non-productive time (NPT) occurred and large volumes of oil-based mud (OBM) was lost to the formation.
The operator utilized STAR SHIELD through the active system with concentrations ranging from 6-8 lb/bbl. The Wilcox formation was drilled with a mud weight of 13.5 lb/gal. Below the Wilcox, (+/- 10,000 feet) the mud weight was increased to 14.5 lb/gal and maintained, resulting in full returns. At the kick-off point (+/- 13,000 feet) the operator began a 6 ¾-in. slim-hole design to total depth of 19,000-ft. measured depth (MD).
By incorporating STAR SHIELD as standard drilling practice in the drilling fluid, the operator significantly reduced the total well costs by eliminating the intermediate casing string and drilling to total depth with full returns. The operator eliminated wellbore instability and NPT on subsequent wells. Currently, the operator continues to use STAR SHIELD in their drilling program in the Eagle Ford to address problematic formations and gas influx.