Location: Saudi Arabia
Hole problems anticipated in the 12¼” hole sections are partial/severe losses and sloughing shale. Partial/Severe loss is potential in WARA (5374′) and SAFANIYA (5740′) formations, while the interval of KHAFJI between 6,134 ft -6,670 ft is an unconsolidated sand section. Shale along the entire 12¼” hole section is fluid sensitive. Shale sloughing and/or swelling can arise at any time along this section. Interval for losses between 5,374 ft – 5,915 ft (541 ft footage).
The 12¼” hole was drilled using OBM of 81 PCF (10.8+ ppg). Initially 3 ppb FRACSEAL was maintained in the active OBM. Drilling at 5100 ft (200 ft above predicted 1st loss zone to encounter) FRACSEAL concentration was increased from 3 ppb to 10 ppb. While drilling the expected interval for losses between 5,374 ft – 5,915 ft, added 2 sacks per hour of FRACSEAL to replenish portion screen out with drilled cuttings. FRACSEAL of 9 ppb was retained in active OBM from 6,670 ft till 8,068 ft (9⅝”csg point).
Not even one predicted hole problems encountered. It was a smooth drilling operation. The hole was slick and in good shape. Wara, Safaniya were protected, Khafji was stabilized from possibly partial losses and differential sticking. Caving and sloughing shale was not observed throughout drilling.