A method of performing line insulation monitoring of a pair of conductor lines at least partially located in a cable is provided, comprising the steps of providing a first power switch in a first conductor line of the pair and a second power switch in a second conductor line of the pair, providing a line insulation monitor at a first end of the pair of conductor lines, electrically connected to the pair of conductor lines, at the second end of the pair of conductor lines, electrically connecting the first and second conductor lines, placing the first and second power switches into a monitoring configuration wherein the first power switch is closed while the second power switch is open, and using the line insulation monitor to monitor the insulation of the conductor lines.

Downhole electrical energy harvesting and communication in systems for well installations having metallic structure carrying electric current, for example CP current. In some instances there is a harvesting module (4) electrically connected to the metallic structure (2) at a first location and to a second location spaced from the first location, the first and second locations being chosen such that, in use, there is a potential difference therebetween due to the electric current flowing in the structure (2); and the harvesting module (4) being arranged to harvest electrical energy from the electric current. In addition or alternatively, there may be communication apparatus (4, 5, 6) for communication by modulation of the current, for example CP current, in the metallic structure (2).

Dual-walled coiled tubing assemblies are used to dispose a flow actuated pump into a wellbore. Dual-walled coiled tubing assemblies include an inner coiled tubing string and an outer coiled tubing string.

A method for providing tension to a data or power transmission line in a pipe includes inserting a transmission line into a transmission line channel of a pipe. The transmission line has a first end and a second end and is inserted into a first end of the pipe second-end-first and has a first tension-load-supporting mechanism attached to the first end of the transmission line. The method includes applying a first level of tension to the transmission line in the pipe and applying a second tension-load-supporting mechanism to the second end of the transmission line while the first level of tension is applied to the transmission line. The method further includes removing the first level of tension from the transmission line to maintain a second level of tension along the transmission line between the first and second tension-load-supporting mechanisms.

The present disclosure provides a current monitoring circuit for monitoring current in a electromagnetic telemetry system. The circuit includes a transmitter configured to generate an output current. One or more current monitors are positioned to detect current at or near the electrode stations or at positions along the one or more loops. Measured current data is transmitted back to the transmitter, which may be shut down if necessary. Methods for monitoring current in an electromagnetic telemetry system are also provided.

An apparatus for communicating a signal downhole includes a downhole pipe configured to be coupled to another downhole pipe and a protection tube secured to the downhole pipe. A transmission line is disposed in the protection tube and configured to communicate the signal. A communication device is disposed in the downhole pipe and configured to communicate the signal to another downhole pipe. An end of the transmission line is configured to be axially movable with respect to the downhole pipe in order to have the end of the transmission line extending from the protection tube to establish a connection between the transmission line and the communication device.

This subsystem is an element of an oil well improvement (disasters preventive) system for offshore wells. This subsystem modifies existing in-well; data transmission equipment, data formatting & processing, and further modifies the processing of the existing sensors and remote controlled devices to provide enhanced capacity, reaction time & reliability for dynamically monitoring & controlling in-well resources. This sensor data and controlled tool status is further integrated into a single data base along with all seabed & platform devices and all related information (formation survey, drill plan, etc). The subsystem processes this data and develops instant status of operational conditions and provides recommendations/alerts/automated controls. Although the primary objective of the subsystem focuses on reducing/eliminating the disastrous effects of blowout, the subsystem also provides the means to alter/improve the normal/uneventful well drilling processes.

An information transmission apparatus for logging while drilling comprises a hollow drilling rod and at least one cable. The drilling rod comprises at least one first drilling rod member and at least one second drilling rod member spliced to each other alternately. The first drilling rod member comprises a through hole, and the second drilling rod member comprises a stepped hole. The cable comprises a fixed end, a connected end, and a folded portion connect the fixed end to the connected end. Each of the cables is fixed in the stepped hole through a fixed end or is connected to a connected end of an adjacent cable. The connected end may be stretched along the stepped hole, and stretched through the through hole to be electrically connected to a logging instrument or a fixed end of the adjacent cable. The apparatus provides protection for a cable through a hollow drilling rod, thereby improving the transmission reliability.

The present disclosure relates to a power isolation adapter which can enable the use of multiple power sources in a bottom hole assembly (BHA) by isolating the power sources on a tool bus while maintaining a communication bus across the BHA. Such power sources may be part of a measurement-while-drilling (MWD) module, such as a mud turbine generator, providing power as a DC signal. The power isolation adapter isolates the power sources by blocking DC signals, but maintains an AC communication bus across the BHA. The ability to use multiple power sources in a BHA thus allows for more complex BHA configurations that normally could not be powered using a single power source.

A method and apparatus for downhole data transmission. The method comprising monitoring electrical impedance properties of a downhole formation by applying an electrical signal between a first portion and a second portion of a drill string that are electrically insulated from each other by an insulating portion, selecting a frequency for transmitting data by electromagnetic telemetry based at least in part on the monitored electrical impedance and transmitting the data by encoding the data in a waveform having the selected frequency and applying the waveform between the first portion and the second portion of the drill string.