Abstract: A downhole system and method of performing an operational action with the downhole system. The downhole system includes a downhole string having a flow channel therethrough, a first turbine generator for generating electrical energy when a flow rate of a fluid through the flow channel is within a first flow rate range, and a second turbine generator for generating electrical energy when a flow rate of the fluid through the flow channel is within a second flow rate range. A first pulser at a downhole location in the downhole string transmits a pressure pulse communicative of data generated downhole using electrical energy generated by one of the first turbine generator and the second turbine generator. A sensor at a surface location receives the pressure pulse, and a control unit performs the operational action based on the data communicated by the pressure pulse.

Abstract: A method and apparatus for determining a gas influx into a wellbore. A work string defining an inner bore area and an annulus area, with a pair of inner bore sensors in the inner bore and a pair of annulus sensors in the annulus. A processor sets a gas influx alarm limit based on a steady-state value of an acoustic parameter measured by the pair of inner bore sensors in an absence of a gas influx and a steady-state value of the acoustic parameter measured by the annulus sensors in the absence of the gas influx. The processor determines a gas influx in the wellbore when a subsequent value of the acoustic parameter is outside of the alarm limit and performs an action at the work string to counteract the gas influx in the wellbore.

Abstract: A method and apparatus for determining a gas influx into a wellbore. A work string defining an inner bore area and an annulus area, with a pair of inner bore sensors in the inner bore and a pair of annulus sensors in the annulus. A processor sets a gas influx alarm limit based on a steady-state value of an acoustic parameter measured by the pair of inner bore sensors in an absence of a gas influx and a steady-state value of the acoustic parameter measured by the annulus sensors in the absence of the gas influx. The processor determines a gas influx in the wellbore when a subsequent value of the acoustic parameter is outside of the alarm limit and performs an action at the work string to counteract the gas influx in the wellbore.

Abstract: A downhole system and method of performing an operational action with the downhole system. The downhole system includes a downhole string having a flow channel therethrough, a first turbine generator for generating electrical energy when a flow rate of a fluid through the flow channel is within a first flow rate range, and a second turbine generator for generating electrical energy when a flow rate of the fluid through the flow channel is within a second flow rate range. A first pulser at a downhole location in the downhole string transmits a pressure pulse communicative of data generated downhole using electrical energy generated by one of the first turbine generator and the second turbine generator. A sensor at a surface location receives the pressure pulse, and a control unit performs the operational action based on the data communicated by the pressure pulse.

Abstract: A drive and steering control system for an endless track vehicle such as a sugar cane harvester. A dual path hydrostatic drive has a pair of variable volume pumps connected for bidirectional flow to respective hydraulic motors driving a pair of endless tracks. A speed control lever and steering wheel mechanism each provide control inputs to a microprocessor which in turn controls the variable volume hydrostatic pumps to control vehicle velocity and turning in a way that matches control for wheeled vehicles. RPM sensors for the hydraulic motors provide a feedback signal that is used to compensate for equipment variation and to keep the vehicle on the course intended by the operator.