The project goal is to field-test a state-of-the-art microhole coiled tubing drilling (CTD) rig and to conduct technology-transfer efforts to generate interest in and gain acceptance of the technology. Utilization of this technology will enable development of marginal oil and gas wells while minimizing environmental impact.
Gas Technology Institute
Des Plaines, IL
Advanced Drilling Technologies (ATD)
Currently, about 800 wells are drilled per year using coiled tubing in the U.S., with the potential for a much larger number if CTD becomes a proven tool. In addition, the cost savings and rig design with CTD are likely to facilitate additional production through the development of resources that are uneconomic at current drilling costs. The most significant economic impact will be the additional oil andgas resources that will be made available to U.S. consumers.
Twenty-three project wells have been drilled and completed in the Niobrara formation of Western Kansas and Eastern Colorado. A total 40,000 feet of 4 3/4-inch hole was drilled, ranging in depth per well from 1,500 feet to 3,100 feet. Each of the wells was monitored for rig performance, including rate of penetration, time for rig mobilization, and other parameters. The performance of the drilling rig has continuously improved throughout the project. Initially, 1,500-foot Niobrara wells were drilled in one day. Currently, 3,000-foot Niobrara wells are being drilled in 19 hours, including move-in, rig-up, drilling, logging, setting casing, cementing, and rig-down move-out.
Dissemination of project results have been accomplished through reporting, news releases, articles in trade journals and through presentations at conferences and workshops. Summary presentations of the project were presented at PTTC conferences in Wichita, Kansas; Denver, Colorado; and Cambridge, Ohio. Presentations were also made at the Hart Unconventional Gas conference in Fort Worth, TX and at the DEA workshop in Galveston, TX. All of the presentations were given between March and June 2006.
Presently CT drilling represents less than one percent of U.S. activity. A recent analysis by GTI shows that initial market penetration in the U.S. market will come for vertical wells from 0-5000 feet, then moving to horizontals. After 2010, with additional technology development, CT drilling will spread to the 5,000-10,000 feet depth range. By 2025 CT drilling will represent 28% of wells in the 0-5000 feet range and 19% of the wells in the 5,000-10,000 ft range. Based upon an average 25% reduction in drilling costs compared to conventional drilling, annual savings reach a level over $6 billion by 2025. It should be noted that CT drilling with today’s technology does not apply to all areas. With this lower cost gas, resources that would not have been economic with conventional methods will be developed. Assuming current technology GTI estimates some 11 Tcf of non-conventional gas at depths to 5000 feet could be economically recovered from the US natural gas resource base. An essentially equal volume of conventional gas, half from new fields and half from reserve appreciation, could be recovered.
In this project, a next-generation microhole CTD rig is being field-tested. The rig being used is the MOXIE experimental rig fabricated by ATD/CTS specifically for micro-hole CTD to depths as great as 5,000 feet.
Sites in Kansas and Colorado that have known gas resources at 1,200-3,500 feet in depth are being drilled and cased with the microhole CTD rig. The rig is being evaluated in six areas: mobilization and rig-up time, drilling surface and production holes, running surface casing and cementing, logging and evaluation, running production casing and cementing, and rigging down and moving the equipment from the drill-site. Measurements are being made of time, equipment weight, penetration rates, rpm, torque, drag, pumping pressures, mud properties, solids control, and other measures of rig performance.
During the early field testing and monitoring of the microhole CT rig, the percentage of time for each operation was calculated. Operations considered included rig-up time, 16%; pick-up of bottomhole assembly (BHA), 16%; drilling, 26%; lay-down of the BHA, 16%; logging, 11%; and casing/ cementing, 20%. The relatively low drilling time (21%) illustrates the advantage of using CTD where the drill pipe connection is eliminated when compared with conventional drilling.
All of the field work was completed in late 2005. Twenty-three project wells were monitored in the field with over 40,000 feet of 4 3/4-inch hole drilled. The project contract required only three wells and 1,000 feet of 4 3/4-inch hole be drilled. The project ended in May 2006. The final report was prepared and submitted in May 2006.
$1,000,000 (50% of total)
Microhole Approach to Microdarcy Reservoirs; Application of Microhole Coiled Tubing Drilling to the Niobrara Gas Play in Kansas and Colorado, Hart’s E&P, February 2006.
A Rescue Plan for Shallow Gas, MHT Has Seismic Implications, AAPG Explorer, December 2005.
Microhole Technology Successful in Shallow, Low-Margin Fields, press release, Gas Technology Institute, Des Plaines, IL, September 23, 2005.
Perry, K., Batarseh, S., Gowelly, S., Hayes, T., Field Demonstration of Existing Microhole Coiled Tubing Rig (MCTR) Technology, Final Technical Report, DOE Contract DE-FC26-04NT15482, May 9, 2006.