| 摘要 |
A power supply arrangement (Fig. 2) for a well drilling installation enables hydraulic energy to be made available downhole for use in, for example, generating MWD pulses or operating hydraulic devices or for conversion to electrical energy. A piston (31) is exposed to the pressure difference between the interior of the drill string (1) and the return annulus (13) and compresses a resilient member (35) when circulation of drilling fluid commences. A one-way valve (33) locks the piston (31) against return movement when circulation of drilling fluid ceases. The lock can be released by a solenoid valve (37), allowing the stored energy of the resilient member (35) to be released as hydraulic energy in the circuit in which the valves (33, 35) are connected: the stored energy can be released at any time during the period of non-circulation of drilling fluid. An alternative power supply arrangement enables hydraulic energy to be made available while drilling fluid is being circulated and yet another arrangement enables hydraulic energy to be made available at the surface rather than downwhole. |
