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Abstract

A long (33 days) pumping test has been carried out on the geothermal borehole at Marchwood to obtain information about the behaviour of the well, the properties of the Triassic aquifer, and the quality of the geothermal brine. The test was carried out using a 27-stage electric submersible pump, which was installed using mobile cranes and a purpose-built gantry. Despite some uncertainty about this method of installation, it was generally trouble-free, though perhaps slower than using a rig. A pressure and temperature sensor was installed in the borehol near provide access past the pump. Corrosion test pieces were inserted below the pump and in the surface discharge pipe. The borehole was pumped at an average rate of 29 l/s for 33 days between 6 April and 9 May 1981. At the end of pumping, the down-hole pressure had been reduced from 17.39 MN/m**2 to 13.63 MN/m**2 corresponding to a fall in the water level from about 5 m to about 370 m below ground level. Down-hole temperature stabilized at 73.6 degrees C, and could the maximum recorded surface temperature was 71.6 degrees C. Analysis of discharge and drawdown data suggests that the aquifer has a transmissivity of about 7 m**2/day. Leakage through or from less permeable strata reduced the rate of drawdown, but a hydraulic boundary became effective after pumping for about 16 days. Given both these effects, the pumping water level is likely to be depressed to at least 550 m below ground level after 20 years pumping at 29 l/s.

Additional information

Authors: PRICE M, NATURAL ENVIRONMENT RESEARCH COUNCIL - INSTITUTE OF GEOLOGICAL SCIENCES, LONDON (UK);ALLEN D J NATURAL ENVIRONMENT RESEARCH COUNCIL - INSTITUTE OF GEOLOGICAL SCIENCES, LONDON (UK), NATURAL ENVIRONMENT RESEARCH COUNCIL - INSTITUTE OF GEOLOGICAL SCIENCES, LONDON (UK)
Bibliographic Reference: EUR 8318 EN (1984) MF, 66P., BFR 120, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
Record Number: 1989122035100 / Last updated on: 1987-01-01
Category: PUBLICATION
Available languages: en