Location: Offshore Norge
Wishing has a water sensitive shale in the 8½” section prone for mud losses, hole instability, and need to be drilled using oil based mud, resulted in a costly drilling operation. A highly deviated and horizontal sections in this field become even more difficult to drill.
After the 9-5/8″ casing was set at 947,5 m, a horizontal 8½” hole was drilled. From 955 m the active mud was treated with FRACSEAL. Had smooth drilling and static hole until 1060 m, then a static loss (S/L) at 6 m3/hr (±38 bph) was observed. While maintaining FRACSEAL 6-8 ppb in the system drilling was continued penetrating further loss interval. At 1120 m had losses at 12 m3/hr (76 bph), 6 m3 (±38 bbl) STOPLOSS pill @ 37 ppb was pumped and followed by a hesitation squeeze. The incorporation of FRACSEAL in the active OBM was through direct additions or sweeping pills containing 15-20 ppb FRACSEAL.
This section was drilled with minimized problems. Maintaining FRACSEAL in the active system gives tremendous effect to drilling efficiency. Hole remained relatively stable throughout horizontal drilling operation. It becomes product and treatment of choice for drilling the same section in this field, especially for high-angle and horizontal trajectory.