| 摘要 |
A control system especially but not exclusively for use downhole in a well bore during drill stem testing, includes first means (38) for producing a first response to a changing stimulus (eg. well bore pressure changing at a varying rate); second means (58) for producing a second response to the stimulus, which response is initially masked by the first response; and signal producing means (6) arranged to produce a signal when the second response exceeds the first response. In one embodiment, two components (38,58) are moved in different directions, but in a net first direction, until the rate of change of the pressure is sufficiently low (e.g. near steady state), at which time the rates of movement of the two components produce net movement in a second direction which initiates a control valve (6) to produce a signal. <IMAGE> |
