| Abstract |
Geothermal developers have been expanding their use of electric submersible pump (ESP) technology in recent years. This paper provides a comparison of ESP technology with line-shaft pump (LSP) technology, which has historically dominated the market for artificial lift in geothermal production wells. The paper them compares typical characteristics of ESPs in geothermal applications in the USA and Turkey, with respect to production temperatures, production rates, pump setting depths, and run times. ESPs in the USA are operating at production temperatures up to 168°C (334°F) and at production rates up to about 635 tonnes/hour (tph) (1,400 thousand pounds per hour, kph). Pump-setting depths for ESPs in the USA are typically less than 530 meters (1,740 feet). Run times for ESPs in the USA have typically extended to 2-3 years (in one instance, over 7 years), and improvements in ESP designs and attention to power quality appear likely to increase run times in the future. In Turkey, the market for ESPs in geothermal applications is relatively new, and run times for these ESPs are typically shorter by virtue of shorter operating histories. For the Turkish ESP installations considered in this paper, the maximum production temperature was 162°C (324°F), and the maximum production rate was 410 tph (904 kph). These values are somewhat lower than in the USA, but the differences appear to relate more to resource characteristics than to ESP capabilities. In contrast, ESPs in Turkey have been set at much greater depths (up to 979 meters / 3,212 feet). Moreover, ESPs in Turkey have been adapted to allow scale inhibition down-hole, which is not usually necessary in the USA. Significant advantages of ESPs in comparison to line-shaft pumps (LSPs) include: (1) ESPs can be installed in deviated wells; (2) ESPs can be set at greater depths; and (3) ESPs do not require injection of lube-oil that can contaminate both reservoir zones and surface facilities. As ESP technology improves, there is considerable potential for use of this technology to rejuvenate output from formerly self-flowing wells in pressure-depleted fields. |