A combined telemetry system that can be used while drilling a wellbore consists of a multi-hop telemetry method and a single-hop telemetry method combined in parallel. The multi-hop and single-hop methods can be operated in parallel, for example, so that each telemetry method caries data concurrently from the Measuring-While-Drilling tool located in the Bottom-Hole-Assembly. The multi-hop and single-hop methods can also be operated in series, for example, so that data from the Measuring-While-Drilling tool located in the Bottom-Hole-Assembly are first carried with the single-hop telemetry method and then transferred to the multi-hop telemetry method at one or more node(s) close to the surface. Preferably, the multi-hop telemetry method can also carry data from along-string sensors. Another combined telemetry system that can be used while drilling a wellbore consists of two single-hop telemetry methods combined in parallel.

There are described downhole devices, methods and other apparatus, which may be used to generate energy, monitor fluids and/or provide control signals or otherwise trigger for actuation. The devices, methods, etc. may provide improved autonomy and/or accuracy, while at the same time minimise any effect on the operation of a well. Such devices and methods may be particularly useful downhole and in remote locations. An example of a device comprises a generating material having a fluid contact surface, that contact surface being configured to be in contact with a fluid downhole. The generating material may be configured to generate an electric charge at the material in response a fluid at the contact surface. In some examples, the device further comprises a signal source configured to provide a signal in response to a generated electric charge at the generating material.

There are described downhole devices, methods and other apparatus, which may be used to generate energy, monitor fluids and/or provide control signals or otherwise trigger for actuation. The devices, methods, etc. may provide improved autonomy and/or accuracy, while at the same time minimise any effect on the operation of a well. Such devices and methods may be particularly useful downhole and in remote locations. An example of a device comprises a generating material having a fluid contact surface, that contact surface being configured to be in contact with a fluid downhole. The generating material may be configured to generate an electric charge at the material in response a fluid at the contact surface. In some examples, the device further comprises a signal source configured to provide a signal in response to a generated electric charge at the generating material.

A telemetry and communication system and method for communication between a well production system and a well assist system. The system may comprise a well production system, which may comprise a telemetry sensor disposed in a production well below a highly conductive layer and a transmitter. The system may further comprise a well assist system comprising a sensor which is operable to receive information from the transmitter. A method for providing telemetry and communication may comprise determining a location of a well assist system for a well production system, deploying the well assist system to the location, disposing a sensor from the well assist system below a highly conductive layer, and receiving information with the sensor, the information being transmitted from a transmitter of the well production system disposed below the highly conductive layer.

A telemetry and communication system and method for communication between a well production system and a well assist system. The system may comprise a well production system, which may comprise a telemetry sensor disposed in a production well below a highly conductive layer and a transmitter. The system may further comprise a well assist system comprising a sensor which is operable to receive information from the transmitter. A method for providing telemetry and communication may comprise determining a location of a well assist system for a well production system, deploying the well assist system to the location, disposing a sensor from the well assist system below a highly conductive layer, and receiving information with the sensor, the information being transmitted from a transmitter of the well production system disposed below the highly conductive layer.

Systems and methods are presented for reducing electrical interference in measurement-while-drilling (“MWD”) data. An example may include, among other features a MWD data acquisition system including an analog data reception for receiving analog MWD data, an analog-to-digital conversion circuit, at least one isolation circuit for electrically isolating the analog data reception circuit and the analog-to-digital conversion circuit from a digital data transmission circuit. In some embodiments, a power isolation circuit may electrically isolate an analog section power domain from a digital section power domain. The isolation techniques may improve the quality of the analog signal received.

Electromagnetic field monitoring methods and systems for obtaining data corresponding to subsurface rock formations. An electromagnetic field monitoring system includes an electromagnetic transmitter located downhole in a well bore and configured to radiate electromagnetic radiation into a subsurface formation; a fiber optic cable coupled with a fiber optic interrogator, the at least one fiber optic cable and the interrogator located at the surface; and an array of electromagnetic sensors integrally formed in the fiber optic cable and configured to detect the electromagnetic radiation radiated through the subsurface formation. A method of detecting electromagnetic radiation at the surface of an oil well includes transmitting, from an electromagnetic transmitter, electromagnetic radiation into a subsurface formation; and sensing, from the subsurface formation, electromagnetic radiation at the surface of the oil well.

Electromagnetic field monitoring methods and systems for obtaining data corresponding to subsurface rock formations. An electromagnetic field monitoring system includes an electromagnetic transmitter located downhole in a well bore and configured to radiate electromagnetic radiation into a subsurface formation; a fiber optic cable coupled with a fiber optic interrogator, the at least one fiber optic cable and the interrogator located at the surface; and an array of electromagnetic sensors integrally formed in the fiber optic cable and configured to detect the electromagnetic radiation radiated through the subsurface formation. A method of detecting electromagnetic radiation at the surface of an oil well includes transmitting, from an electromagnetic transmitter, electromagnetic radiation into a subsurface formation; and sensing, from the subsurface formation, electromagnetic radiation at the surface of the oil well.

A method of communicating through the earth which includes the steps of using a digital pulse train to generate a sweep pulse train which controls the frequency of a magnetic field at a first location, and at a second location, detecting the magnetic field and producing a signal at a frequency dependent on the frequency of the sweep pulse train, and extracting a replica of the digital pulse train from the signal.

A method of communicating through the earth which includes the steps of using a digital pulse train to generate a sweep pulse train which controls the frequency of a magnetic field at a first location, and at a second location, detecting the magnetic field and producing a signal at a frequency dependent on the frequency of the sweep pulse train, and extracting a replica of the digital pulse train from the signal.