Clowser Well Service, a regional expert in gas exploration drilling headquartered in Salem, W.V., recently was called upon to help increase production on active gas reserves that had been in existence for the past 10 years. This was accomplished by deepening the hole almost 2,000 feet with a new PCD carbide bit from Numa Hammers. Clowser was selected for this project because of its reputation for providing superior results in the gas drilling industry.
The existing hole originally was drilled to a depth of 3,715 feet, but no longer was yielding the proper flow of gas. In order to reach a deeper pay zone, Clowser selected a Numa Champion 40 downhole hammer and 43⁄4-inch PCD bit. The new bit was chosen because it was specially designed for oil and gas drilling applications consisting of highly abrasive and medium-hard rock formations. Due to the increased strength and wear resistance of Numa’s PCD carbide, the bits will not lose gauge size. This allows the operator to run DTH products longer and deeper.
Clowser set up over the hole with a Cooper 150 rig having 1,050/150 cfm/psi of air and a 600-psi booster. Project requirements deemed Clowser to trip down 51⁄2-inch casing to the bottom of the hole to begin drilling a 43⁄4-inch hole through a shale and sandstone formation. When they began drilling, the crew quickly realized that the hole would not dry up, so they began using foam and water injection to properly clean the hole. This decision was critical to providing the proper conditions to maximize the drilling efficiencies of the PCD carbide bit. Drilling continued until a final depth of 5,655 feet was reached, which took only 42 hours to complete. The penetration rate for the Champion 40 and PCD bit averaged out to be 46.2 feet per hour.
Typically in the past, methods used for drilling gas holes deeper included the use of roller cone bits and/or journal bearing bits. Neither of these provided a cost-effective way of drilling in this type of application due to their limited life cycle and very high cost. If roller cone bits were used on this hole, it would have required two, possibly three bits to be used instead of the one PCD carbide bit used by Clowser. In fact, one of the PCD bits used showed no measurable wear after drilling the hole, and could be used on future projects. Any longer amount of time required to drill would have increased fuel cost and rig time to trip in and out of the hole to replace bits.
When Clowser Well Services was charged with the task of finding the most cost-effective means of drilling deeper in the gas patch, they were able to achieve their desired results.