Mud pressure control system
First Claim
1. A down-hole signal transmitter for a mud-pulse telemetry system, comprising a flow constrictor defining a throttle orifice for the mud passing along a drill string, a throttling member displaceable as a whole towards and away from the throttle orifice to vary the throughflow cross-section of the throttle orifice, a turbogenerator for supplying a measuring instrument and arranged to be driven by the mud flow passing along the drill string, and control means for controlling displacement of the throttling member towards and away from the throttle orifice to modulate the mud pressure, wherein the control means is coupled to the rotor of the turbogenerator and is adapted to displace the throttling member in one direction when the electrical load of the turbogenerator is such that the torque required to drive the rotor exceeds the maximum torque available for driving the rotor, and to displace the throttling member in the opposite direction when the electrical load of the generator is such that the torque required to drive the rotor does not exceed the maximum torque available for driving the rotor.
9 Assignments
0 Petitions
Accused Products
Abstract
A down-hole signal generator for a mud-pulse telemetry system comprises a flow constrictor defining a throttle orifice for the mud passing along a drill string, a throttling member displaceable with respect to a casing to modulate the mud pressure for the purpose of transmitting measurement data up the drill string, and a turbogenerator incorporating an electrical generator within the casing. The flow constrictor and casing form an integrated unit which is installed within a drill collar and is retrievable by drawing it up the inside of the drill string. The throttling member is displaced by a pump according to the torque required to drive the rotor of the generator which is dependent on the electrical load of the generator. The pump incorporates a rotary valve member which supplies the output of the pump to one or other side of a double-acting ram according as to whether the valve member is rotating with a first phase of rotation or a second phase of rotation. The phase of rotation is determined by a torque-sensitive actuator coupled to the valve member by a shaft and incorporating an escapement plate tiltable about an axis transverse to the shaft by a torque drive arm for driving the rotor.
9 Citations
10 Claims
- 1. A down-hole signal transmitter for a mud-pulse telemetry system, comprising a flow constrictor defining a throttle orifice for the mud passing along a drill string, a throttling member displaceable as a whole towards and away from the throttle orifice to vary the throughflow cross-section of the throttle orifice, a turbogenerator for supplying a measuring instrument and arranged to be driven by the mud flow passing along the drill string, and control means for controlling displacement of the throttling member towards and away from the throttle orifice to modulate the mud pressure, wherein the control means is coupled to the rotor of the turbogenerator and is adapted to displace the throttling member in one direction when the electrical load of the turbogenerator is such that the torque required to drive the rotor exceeds the maximum torque available for driving the rotor, and to displace the throttling member in the opposite direction when the electrical load of the generator is such that the torque required to drive the rotor does not exceed the maximum torque available for driving the rotor.
Specification