December 2004 Supplement    New Rig Designs

Cost-effective rig for casing or drill pipe drilling

Continued in-field development of already-proven areas challenges industry to economically exploit smaller and smaller pockets of recoverable reserves. Casing While Drilling (CWD) is the perfect solution for these types of wells with difficult layers, such as depleted zones and unstable formations. Huisman Special Lifting B.V. of the Netherlands, and Drillmar Inc., in a technology development joint venture, have developed an innovative new rig concept, the LOC250, Land and Offshore Containerized 250-t rig designed to take advantage of today’s emerging CWD technology to reduce costs and environmental impact. Two rigs are being built, the first expected to be operational by June 2005.

With such wells located worldwide, transportability is the key. Also, CWD is not the solution for all wells; therefore, efficient drill pipe drilling is added to expand the rig’s workability.

LOC250 rig for drilling with casing or drill pipe can be packaged and moved in 17 ISO containers.

ISO containers are the most standardized units in transportation. To reduce mobilization/ rig move costs, the complete rig can be transformed from a functioning land or offshore platform rig into 17 ISO containers. Such container modular design enables the rig’s versatility, allowing utilization in various modes – land, skid structure on jungle pads, offshore platforms, or barges for drilling on lakes or swamps. With additional modules such as additional mud pumps, increased hook load, additional mud tanks, arctic-pack and a silent-pack the versatility is further increased.

Next to highly efficient casing handling, drill pipe handling is also incorporated in the design. The rig takes advantages of both techniques, CWD reduces drilling days by as much as 30%, while drill pipe drilling enables openhole completions, and applications of packer setting, liners, screens, etc.

The philosophy is that the drill pipe handling is identical to casing handling, enabling transfer of technical/ operational learning from CWD to drill pipe and vice versa. The tubulars are upended by a fast fully automated pipe handler, and are taken over by the elevators. The top drive is utilized to make up connections. Automated power slips are integrated inside the rotary table.

To reduce flat time activities, BOPs are pressure tested off-line on a test stump that also serves as a mouse hole. Also, BHAs can be made up and broken out offline using the crown mounted service crane as a stand builder.

The fully automated drill floor and the crown mounted service crane remove personnel from harm’s way, eliminating the potential for many accidents. The smaller loads of the rig also reduce risk for accidents during moves. Adverse environmental impact is minimized by reducing hydrocarbon emissions and the location foot print. The cascading shaker provides dryer cuttings, reducing solids disposal wastes. And the 125-ft mast does not “pollute” the horizon, which can prohibit a well program in some locals.

The rig is a fully balanced operational rig. All components, such as the drawworks, mud pumps, power unit, mud system and BOPs, are tuned. An integrated control and monitoring system ensures trouble free operation. Web-based remote diagnosis and trouble shooting is incorporated in the monitoring system.