Directional Drilling and Equipment for Hot Granite Wells
Directional drilling technology was extended and modified to drill the first well of a subsurface geothermal energy extraction system at the Fenton Hill, New Mexico, hot dry rock (HDR) experimental site. Borehole geometries, extremely hard and abrasive granite rock, and high formation temperatures combined to provide a challenging environment for directional drilling tools and instrumentation. Completing the first of the two-wellbore HDR system resulted in the definition of operation limitations of -many conventional directional drilling tools, instrumentation, and techniques. The successful completion of the first wellbore, Energy Extraction Well No. 2 (EE-21), to a measured depth of 4.7 km (15,300 ft) in granite reservoir rock with a bottomhole temperature of 320 C (610 F) required the development of a new high-temperature downhole motor and modification of existing wireline-conveyed steering tool systems. Conventional rotary-driven directional assemblies were successfully modified to accommodate the very hard and abrasive rock encountered while drilling nearly 2.6 km (8,500 ft) of directional hole to a final inclination of 35{sup o} from the vertical at the controlled azimuthal orientation. Data were collected to optimize the drilling procedures far the programmed directional drilling of well EE-3 parallel to, and 370 metres (1,200 ft) above, Drilling equipment and techniques used in drilling wellbores for extraction of geothermal energy from hot granite were generally similar to those that are standard and common to hydrocarbon drilling practices. However, it was necessary to design some new equipment for this program: some equipment was modified especially for this program and some was operated beyond normal ratings. These tools and procedures met with various degrees of success. Two types of shock subs were developed and tested during this project. However, downhole time was limited, and formations were so varied that analysis of the capabilities of these items is not conclusive. Temperature limits of the tools were exceeded. EE-2. Commercial drilling and fishing jars were improved during the drilling program. Three-cone, tungsten-carbide insert bit performance with downhole motors was limited by rapid gauge wear. Rotary drilling was optimized for wells EE-2 and EE-3 using softer (IADS 635 code) bits and provided a balance between gauge,. cutting structure, and bearing life. Problems of extreme drill string drag, drill string twist-off, and corrosion control are discussed.
- Research Organization:
- DOEEEGTP (USDOE Office of Energy Efficiency and Renewable Energy Geothermal Tech Pgm)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 886097
- Report Number(s):
- SAND-81-0036C; CONF-810105-9
- Country of Publication:
- United States
- Language:
- English
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