Drilling of a 2000 m (6562 ft) borehole for geothermal steam in Iceland

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:7369364

Ragnars, K; Benediktsson, S

A description is given of the drilling and well completion of a 2000-metre (6562-foot) borehole drilled with an electrically driven Gardner Denver 700E rig. Such a borehole is typical of wells drilled at the Namafjall and Krafla high-temperature fields, where bottomhole temperatures exceed 300/sup 0/C (572/sup 0/F) and a 1000-metre (3281-foot) cemented production casing is required. Factors of importance are the drilling procedure, the blowout equipment, and the casing and cementing procedure, as well as the well cost. Initial drilling is done with a percussion drill down to approximately 50 metres (164 feet), and loose surface layers are cased off. Rotary drilling starts at this point. The rotary drilling is carried out with 44.5-cm (17-1/2-in.) insert bits down to 300 metres (984 feet), 31.1-cm (12-1/4-in.) bits down to 1000 metres (3281 feet), and 21.6-cm (8-1/2-in.) bits down to 2000 metres (6562 feet). Directional surveying is carried out to assist in keeping the well vertical. The classification of blowout equipment and the design of the casing program depend on the steam pressure. The 34.0-cm (13-3/8-in.) anchor casing is set down to 300 metres (984 feet) and the 24.5-cm (9-5/8-in.) production casing down to 600 to 1000 metres (1969 to 3281 feet) to seal off aquifers in the upper section as necessary. A 17.8-cm (7-in.) slotted liner is hung from the lower end of the production casing down to the bottom. The main difficulty in cementing the casing is the loss of circulation, which requires a stage cementing collar and perforation of the casing. The total cost of the well described was approximately 1 million US dollars in 1980.

• Research Organization: Orkustofnun National Energy Authority, Reykjavik, Iceland
• OSTI ID: 7369364
• Report Number(s): SAND-81-0036C; CONF-810105-
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150901* -- Geothermal Engineering-- Drilling Technology & Well Hardware
BUILDING MATERIALS
CEMENTS
COST
DEPTH
DEPTH 1-3 KM
DEVELOPING COUNTRIES
DIMENSIONS
DRILLING
DRILLING EQUIPMENT
EQUIPMENT
EUROPE
GEOTHERMAL WELLS
Geothermal Legacy
ICELAND
ISLANDS
MATERIALS
WELL CASINGS
WELL COMPLETION
WELLS
WESTERN EUROPE