Pressure pulse generator system for measuring while drilling

Claim 1

A measurement while drilling apparatus for use in a borehole in which information carrying signals are transmitted by fluid pressure changes in a borehole fluid circulation system employing a pump for forcing fluid flow through said system, a flow restriction in said system causing a well fluid high pressure zone and a fluid low pressure zone in different sides of said restriction, a passageway interconnecting said zones and a power driven valve interposed in said passageway, the openings and closings of said valve causing openings and closings of said passageway, the amount of power required for each opening of said valve exceeding a determined magnitude, a sensor for sensing the magnitude of downhole measurements and generating a succession of electric voltage changes to sequentially cause openings and closings of said valve in response to said downhole measurements, said apparatus comprising: a valve opening means to actuate said valve to cause openings of said passageway; and a power drive comprising a capacitor means and a source of electrical voltage to supply electric current for charging said capacitor means; said power drive being responsive to said electric voltage changes for initiating successive discharges of said capacitor means thus delivering an amount of power exceeding said magnitude with each of said discharges and applying said discharges to said valve opening means to produce successive openings of said passageway; a valve closing means to actuate said valve to cause a closing of said passageway subsequently to each opening of said passageway whereby successive openings and closings of said passageway are produced; said successive openings and closings of said passageway generating said pressure changes in said borehole fluid circulation system.