Ridley, Katrina M (Shell Exploration & Production) | Jurgens, Matthew (Shell Exploration & Production) | Billa, Richard J. (Shell Exploration & Production) | Mota, Jose F. (Shell Exploration and Production)
While there was no flare during drilling, the flare at bottoms up at TD averaged between 10 and 20 feet. Previous experience in the Eagle Ford and other tight gas plays showed this level of gas to be manageable with conventional Rotating Control Device, RCD, and a mud gas separator. There were some losses encountered during the initial 5 ½" production casing cement jobs with a two-slurry design of top of cement at surface and a 12.7 ppg lead and 16.4 ppg tail. This was attributed to formation weakness in the Olmos sand which occurred from 5300 - 6700 ft TVD. Equivalent circulating density, ECD, simulations established this formation as a potential weak point in the production section with an estimated fracture strength between 13 and 14 ppg EMW across the field. Drilling - Phase 2: Establishing Boundaries Wells were initially drilled with a mud weight between 11 ppg and 12 ppg, well below the established upper limit of the Olmos sand. A trial was initiated to determine the lower limit for mud weight in an effort to increase rate of penetration and reduce drill time.