Abstract: A power management technique for a power bus includes a method and apparatus employing a Faraday electrical energy sink for a power bus. In general, the technique powers a power bus from a fuel cell plant when the actual voltage of the power bus is less than or equal to a nominal voltage for the power bus and sinks power from the power bus into the fuel cell plant when the actual voltage exceeds the nominal voltage.

Abstract: To test coiled tubing, at least one test is performed on a coiled tubing that has been used, such as in an oil or gas well. Performing such test includes obtaining a specific output data event (e.g., a nondestructive evaluation test readout) for the used coiled tubing. The specific output data event is compared with a predetermined sequence of output data events (e.g., a collection of data defining a "lifeline" for the coiled tubing) for determining where the sequence and the specific output data event correspond. A coiled tubing status indication is generated in response to where the specific output data event corresponds with the sequence as a measure of a point in the useful life of the used coiled tubing.

Abstract: A self-contained downhole apparatus for being lowered into an oil or gas well to internally record samples of at least one environmental condition comprises three body sections linearly and releasably interconnected. One of the body sections is a selected one of a plurality of transducer housing sections. The selected transducer housing section is mechanically and electrically connected to a second body section containing microcomputer-operated signal processing circuitry. The third body section contains a power supply.

Abstract: A power supply for providing electricity to one or more electrical circuits located downhole in a well comprises a fuel cell adapted to be disposed in the well with the electrical circuit(s). In addition to generating electricity, the fuel cell produces a byproduct liquid, such as water, which can be expelled from the power supply into the well despite substantial pressure, such as hydrostatic pressure, in the well. The fuel cell also generates heat which can be dissipated into the well through the wall of a housing of the power supply. The byproduct liquid can be circulated through the fuel cell to accomplish or assist in this heat dissipation.

Abstract: A self-contained memory gauge includes either semiconductor or magnetic core memory for retaining downhole information related to sampled parameters, such as borehole temperature and pressure. A microprocessor-based computer manages the power utilization by independently and selectably energizing and de-energizing different sections of the gauge. The magnetic core memory is tested for operability, and the addressing of the magnetic core memory is adjusted in accordance with any inoperable memory locations. Samples of the monitored environmental conditions can be taken at variable rates dependent upon software monitoring of the condition, the remaining battery life and the remaining memory capacity and in response to hardware monitored pressure changes. Each sample can be taken to a selectable resolution. A watchdog circuit monitors the microprocessor to insure that it is operating within a preselected time limit.

Abstract: In an oil well instrumentation system, the downhole sensor system is controlled by a computer which is powered-on only during sampling movement. An independent circuit, continuously powered, detects significant sensor rate-of-change values whereby the computer-sampling equipment is powered-on. A self-contained memory gauge includes either semiconductor or magnetic core memory for retaining downhole information related to sampled parameters, such as borehole temperature and pressure. A microprocessor-based computer manages the power utilization by independently and selectably energizing and deenergizing different sections of the gauge. The magnetic core memory is tested for operability, and the addressing of the magnetic core memory is adjusted in accordance with any inoperable memory locations.