The objective of this project is to develop a unique research laboratory within NETL that will function as a Center of Excellence for Advanced Drilling, Completion, and Stimulation. This center is to support NETL’s oil and gas programs through focused laboratory analysis, evaluation, modeling, and applied research in related sciences and engineering—primarily drilling completion and stimulation—with additional potential applications in micro-hole technology.

This project supports SCNGO at NETL by providing test equipment to characterize fluid/rock/cutter interactions at high pressures and temperatures. Most work in this project will be at very high pressures and temperatures (30,000 psi and 250° C.). The overall benefit of this laboratory will be to extend the basic understanding of rock mechanics and drilling under high pressures and temperatures so that more environmentally friendly drilling fluids and methods may be applied by industry in the complex and costly drilling process.

Designated as the Extreme Drilling Laboratory (EDL), this expansion of the NETL R&D infrastructure will provide the missing but critical science to engineer effective and efficient drilling and production of hydrocarbons at greater depths (>20,000 feet) and temperature (250° C.) that the U.S. oil and gas industry does not provide.

National Energy Technology Laboratory 
Morgantown, WV

The oil and gas industry has undergone significant change over the last decade. Penetration rate in deep drilling has been identified by many drilling experts as one of the most significant risk factors threatening the future of the deep gas drilling market. Drilling at deeper, hotter depths has stretched the limits of metals, elastomers, fluids, and cements. Developing and applying advanced materials will reduce the economic and environmental risks associated with drilling in these harsher environments. Relatively few tests have been conducted at higher temperatures.

Geophysics experiments have provided some strength measurements to very high temperatures. In the 1970s, some geothermal rock tests were conducted to 850° F., measuring deformations accurately. But these were dry rocks, with no fluid or cutter interaction attempted. Techniques were developed using in-vessel heating to allow more-precise measurements. There is some interest in well completions in higher temperature formations up to 350° F. Deformation and strength are not very temperature-dependent to 400-600° F., except for shales with high clay. Temperature effects on pore fluids can change rock properties drastically.

Pressure affects rocks more than temperature (temperature affects what the rock contains and the environment around the rock). Many stress-strain curves are available to 60,000 psi. TerraTek has conducted well over 10,000 tests to 60,000 psi. Again, these tests primarily have been dry and, for geo-physical purposes, have not necessarily involved the drilling process. Stiffness and strength increases with confining pressure. Permeability decreases with confining pres-sure. Deformation of rock has been shown to be load path-dependent and time-dependent. The Effective Stress Law generally applies for strength, but for deformation and permeability change, rocks are much more complicated. The effect of rock behavior on drill stability is critical in drilling. Rocks are somewhat stiffer and stronger when loaded rapidly; however, pore fluid movement affects drilling rate.

Results 
To date, development of the research lab is in a very preliminary stage. Work has included EDL planning and decommissioning of old lab space.

Benefits 
The overall benefit of this laboratory will be to extend the basic understanding of rock mechanics and drilling under high pressures and temperatures so that more environmentally friendly drilling fluids and methods may be applied by industry in this complex process.

Summary 
For this project, equipment and infrastructure must be purchased or constructed. Most equipment will be customized and will need to be designed and constructed by specialists in this area—more than likely outside personnel. A state-of-the-art mud laboratory will also need to be equipped.

Near-term goals to be met include designing and building a customized apparatus called the Ultradeep Drilling Simulator (UDS) at an estimated cost of $1.5 million. Without this device, researchers cannot study the interactions of fluids, cutters, and rock under high-pressure, high-temperature (HP/HT) conditions and will be unable to develop the drilling models required to design the more-efficient, cost-effective drillbits and drilling muds needed to drill deep gas wells.

The device will be a multiple/single cutter device with the general specifications to:

• Be capable of withstanding high pressures (>30,000 psi) and high temperatures (>250° C.).
• Be able to monitor and record drilling parameters with adequate precision and speed for analysis (fiber optics to visually observe and record digital data and information).
• Have the capacity to generate reproducible cuttings traceable to specific cutter designs with any drilling fluid and core under as close to expected conditions as possible (deep, HP/HT hard rock).
• Allow observation and recovery of cuttings and drilled cores for analysis easily and quickly.
• Enable fluids, cores, and cutters to be switched out easily.
• Circulate drilling fluids with a nozzle directed at the cutting zone.

The long-term objectives (within 2-5 years) are to 1) develop, based on the laboratory studies, robust and accurate drilling models (computer simulations), 2) establish an HP/HT drilling lab where the interactions among drilling mud, rock, and drilling devices can be investigated, and 3) develop expertise at NETL for deep HP/HT rock mechanics modeling for drilling and simulations of deep HP/HT environments.

(July 2006) 
Decommissioning of old lab space is complete. FY2006 tasks include developing installation and construction plans and safety analysis and review for the EDL, designing and building the UDS, and initiating the mud lab construction. Hazard Analysis was conducted, and Safety Analysis and Review is in process. Personnel continue to work with Terra Tek on developing Ultra-deep Single Cutter Drilling Simulator. University Collaborative work proposal has been initiated to cover rock mechanics expertise.

Funding 
This project was selected through the NETL In-House Research Program.

$1,175,000

NETL – Sue Mehlhoff (Sue.Mehlhoff@netl.doe.gov or 918-699-2044) 
NETL – Dave Lyons (Kenneth.Lyons@netl.doe.gov or 304-285-4379)