A method and apparatus for communicating signals from within an encased borehole including a wireless communications system for transmitting down-hole environmental data signals between a down-hole tool and a surface receiver. The down-hole tool is disposed within a borehole encased in an electrically conductive casing; the receiver is located at the ground surface. The tool includes a conductive upper and lower tool housing, a plurality of down-hole sensors, and a signal generating device. The sensors and signal generating device are housed within the tool. The generating device receives analog or digital signals of the down-hole environmental conditions from the sensors, converts these signals into a modulation pattern signal which is applied to a carrier signal and conducts a modulated carrier signal into the upper and lower tool housings. An upper contactor or spreader electrically connects the upper housing to a first position on an inside wall of the casing. Similarly, a lower contactor or spreader electrically connects the lower housing to a second position on the inside wall of the casing. The first and second positions are spaced-apart by a pre-determined separation, and define a casing conducting portion therebetween. The transmitted drive signal cause a reciprocating current to flow through the conducting portion thereby inducing a voltage potential on the outside of the well-casing which forms corresponding dipolar electromagnetic field in the earth surrounding the conductive portion and propagating the field upward to be received by the surface receiver.
Adaptive neural networks can be used to effectively enhance signal detection in the inherently noisy environment of an oil well. The neural network can be either non-recurrent or recurrent in nature. The system is implemented with a computer that accepts input from at least one sensor mounted to the wellhead or near the wellhead. The detected contaminated signal is a combination of the event signal and the noise from the environment. The event signal can be, for example, the detonation of a perforation gun. The noise can be either random or periodic. The use of adaptive filtering allows the noise to be more precisely predicted and then subtracted from the contaminated signal to produce a cleaner representation of the event signal. Once the predicted noise is subtracted, the remaining event signal can be analyzed using voice or sound recognition systems to produce an output describing what event occurred.
A method and a system for the transmission of information from a well (1; 20) drilled through geological formation layers (3) at least partly cased by metal tubes (4; 23; 24; 31). The method includes the placing in said well of an information transceiver (E) operating by electromagnetic waves created by the injection of an electric signal by a dipole (P1-P2) conductively connected to the metal tubes used for guiding the transmitted waves. In the method, identification takes place of the attenuation of the transmission by certain formation layers (3a, 3b; 25; 30) having a low resistivity and then there is an at least partial electrical insulation of the metal tubes located opposite the low resistivity layers.
Method systems and apparatus for signalling within pipelines. The systems methods and apparatus make use of a unit locatable within a tubular piece of metallic structure for the transmission and/or reception of signals. The unit includes a magnetic material core (6) which provides a path for magnetic flux through the unit (4). A coil (81) is wound around a portion of the magnetic material core (6) to allow the detection and/or application of magnetic flux in the magnetic core (6). At each end of the core (6) there is pair of arms (63) which are arranged for location adjacent the inside surface of the tubular structure. In use magnetic signals flowing in the tubular structure pass through the core (6) and can be detected via the coil (81) in receive mode and similarly signals flowing in the coil (81) can cause magnetic flux to flow through the core (6) and into the metallic structure in transmit mode.
Methods of and apparatus for a downhole communication in a well. The well has a metallic structure which includes an insulated metallic, fluid carrying, control line. The method comprises the steps of applying signals to the control line at a first location and extracting the signals from the control line at a second location.There is also provided a downhole communication system for use in a well having a metallic structure. The metallic structure includes an insulated metallic, fluid carrying, control line. The system comprises means for applying signals to the control line at a first location and means for extracting the signals from the control line at a second location. The control line acts as a signal channel.Other methods and apparatus making use of control line carrying no fluid and/or the metallic shielding of cable having insulated metallic shield are also described.
A downhole string includes a liner and devices positioned outside the liner. One or more control lines extend from the liner devices along the exterior of the liner to one or more connectors that provide connection points inside the liner. The one or more connectors may include electrical connectors (e.g., direct contact connectors), inductive connectors (e.g., inductive couplers), optical connectors (e.g., fiber optic connectors), and hydraulic connectors. The one or more control lines may be electrical lines, fiber optic lines, or hydraulic lines. The downhole string may also be used with a cement protector during cementing operations to protect both the inside of the liner as well as the one or more connectors attached to the liner. The cement protector includes a sleeve that isolates cement from the inside of the liner during a cementing operation so that a liner wiper plug is not needed. The cement protector is engageable to a pulling tool that is attached to a running tool. The running tool in turn is connected to a pipe through which a cement slurry can be pumped. The cement slurry pumped through the inner bore of the pipe enters the sleeve of the cement protector. One or more ports are provided in the cement protector sleeve to enable communication of the cement slurry to an annulus region between the outer wall of the liner and the inner wall of the wellbore. If the apparatus and method is used with a casing, then a running tool may be omitted.
