Abstract: An electromagnetic receiver includes at least one sensor for measuring electromagnetic signals, and a calibration antenna configured to generate an electromagnetic signal at a first frequency.

Abstract: A method for determining a formation electrical property under a sea floor includes obtaining measurement data using a receiver having an impedance lower than an impedance of seawater at a measurement site; correcting the measurement data to obtain corrected data corresponding to data that would have been acquired using a receiver having an impedance matched with the impedance of the seawater; and deriving the formation property from the corrected data.

Abstract: A receiver for electromagnetic measurements includes a polyhedron structure having m faces, where m?4 and m?6: n electrodes each disposed on one face of the polyhedron structure, wherein 3?n?m; and at least one circuitry connected to the n electrodes for signal measurement. A method for electromagnetic measurements includes obtaining a plurality of electric current measurements using a plurality of electrodes each disposed on a surface of a polyhedron receiver, wherein the plurality of electric current measurements comprise at least three different measurements; and determining electric field components in a three dimensional space from the plurality of electric current measurements by using a number of matrices that correlate orientations of surfaces of the polyhedron receiver to a coordinate system in the three dimensional space.

Abstract: A technique includes deploying a monitoring station near the sea surface and on the monitoring station, monitoring a position of a subsurface device as the subsurface device moves in a path between the sea surface and the sea floor. The technique includes communicating an indication of a position of the subsurface device from the monitoring station to a surface vessel.

Abstract: The invention concerns a mobile telephone network (XPLMN) characterised in that it comprises: (a) a radio subsystem (XBBS) and management and routing subsystem (ENSS); (b) said radio subsystem (XBBS) comprising at least a first base station (BTS) link and a second base station (XBTS) link and a link of the base station controllers (BSC, XBSC); (c) the base stations (XBTS) of the first link, communicating directly with their associated base station controllers (BSC) with specific means; (d) the base stations (XBTS) of said second link, communicating with the associated base station controller (XBSC) via the public switched telephone network (PSTN).

Abstract: A two-dimensional array of slot antennas which can provide two-dimensional quantitative dielectric and conductivity images of formations in the region surrounding an earth borehole. The antennas are mounted in a wall-engaging member of a logging device that is moveable through the borehole. Selected ones of the antennas are energized at given times to transmit electromagnetic energy into the formations, the electromagnetic energy being received at other antennas for processing to obtain formation properties.

Abstract: A slot antenna has a square aperture and two current probes at angles to each other in the aperture. The two current probes are excited simultaneously or separately with different signals. By adjusting the amplitude or phase of the signals in the current probes, the angle of the magnetic moment of the antenna can be adjusted. An array of such antennas in an electromagnetic propagation tool for a well-logging device simultaneously provides better standoff performance by adjusting tile magnetic moment to be parallel to a borehole axis, and better image response by adjusting the magnetic moment to be perpendicular to the formation bed. The array can be excited to function as an endfire and broadside array of an electromagnetic propagation tool.

Abstract: A slot antenna has a square aperture and two current probes at angles to each other in the aperture. The two current probes are excited simultaneously or separately with different signals. By adjusting the amplitude or phase of the signals in the current probes, the angle of the magnetic moment of the antenna can be adjusted. An array of such antennas in an electromagnetic propagation tool for a well-logging device simultaneously provides better standoff performance by adjusting the magnetic moment to be parallel to a borehole axis, and better image response by adjusting the magnetic moment to be perpendicular to the formation bed. The array can be excited to function as an endfire and broadside array of an electromagnetic propagation tool.

Abstract: In a form of the disclosure, electromagnetic propagation logging measurements are made for several magnetic moment directions of the electromagnetic energy, and can be examined and/or processed retrospectively in order to select the logging information which has a particular desired characteristic, such as the sharpest imaging of bed boundaries. By scanning the magnetic moment over a wide range of angles, one is assured of obtaining logging information that has a desired attribute, such as image sharpness. This can be determined by viewing a recorded log and/or by automatically processing the log data. Information from other ones of the several logs may be useful in optimizing other attributes, such as standoff immunity or signal-to-noise ratio.

Abstract: A borehole apparatus detects the presence of gas within a formation fluid sample. A light source transmits light rays to an interface between the fluid sample and the flow line. The interface reflects the light rays toward a detector array. The detector array detects light rays having angles of incidences extending from less than the Brewster angle to more than the critical angle for gas. A data base stores information concerning the Brewster angle and critical angle of gas for a plurality of gas volume categories. A processor determines the percentage of gas present in the formation fluid sample and categorizes the fluid sample as high as, medium gas, low gas, and no gas based on the signal from the detector array and the information from the data base.

Abstract: A borehole apparatus detects the presence of gas within a formation fluid sample. A light source transmits light rays to an interface between the fluid sample and the flow line. The interface reflects the light rays toward a detector array. The detector array detects light rays having angles of incidences extending from less than the Brewster angle to more than the critical angle for gas. A data base stores information concerning the Brewster angle and critical angle of gas for a plurality of gas volume categories. A processor determines the percentage of gas present in the formation fluid sample and categorizes the fluid sample as high gas, medium gas, low gas, and no gas based on the signal from the detector array and the information from the data base.

Abstract: A borehole apparatus for analyzing the composition of a formation fluid is disclosed and generally comprises a testing chamber, a means for directing a sample of fluid into the chamber, a light source which emits at least near infrared rays, a spectral detector, a data base means, and a processing means. The light source is preferably an incandescent lamp and the testing chamber includes a window which is substantially optically transparent to at least one near infrared light, and preferably also the near ultraviolet and visible light of the source. The light source is directed at least partly towards the window in the chamber either via collimation or fiber optics. The spectral detector means is preferably a spectrometer which detects and measures the spectra of the light which has been transmitted through and the light which is backscattered by the fluid sample. The preferred data base means stores the spectra at different pressures and temperatures of water, gas, and a plurality of oils.

Abstract: A method and apparatus for investigating earth formations surrounding a borehole operates by selectively heating a region of the formations, and measuring the thermal response to obtain useful information concerning the characteristic length scales of the pores in the heated region. The thermal response is obtained indirectly by measuring the electrical conductivity response. The invention can be utilized to obtain, inter alia, indications of porosity, permeability, and the distribution of pore geometries. In accordance with an embodiment of the method of the invention, the following steps are performed: heating a region of the formations with a series of pulses of microwave electromagnetic energy; measuring the conductivity characteristic of the region which result from the heating pulses; and determining a property of the region of the formations from the measured conductivity characteristic.

Abstract: A system and method are disclosed for wireless two-way communication in a cased borehole having tubing extending therethrough. A downhole communications subsystem is mounted on the tubing. The downhole subsystem includes a downhole antenna for coupling electromagnetic energy in a TEM mode to and/or from the annulus between the casing and the tubing. The downhole subsystem further includes a downhole transmitter/receiver coupled to the downhole antenna, for coupling signals to and/or from the antenna. An uphole communications subsystem is located at the earth's surface, and includes an uphole antenna for coupling electromagnetic energy in a TEM mode to and/or from the annulus, and an uphole receiver/transmitter coupled to the uphole antenna, for coupling the signals to and/or from the uphole antenna. In accordance with a feature of the invention, the annulus contains a substantially non-conductive fluid (such as diesel, crude oil, or air) in at least the region of the downhole antenna and above.

Abstract: An electromagnetic logging apparatus is disclosed which employs dielectric-filled button antennas, in conjunction with tuning elements, to obtain improved operation. The apparatus can be used to measure the dielectric constant of formations surrounding a borehole.

Abstract: The disclosure is applicable to a borehole logging device of the type which includes an elongated body suspendable in a borehole and having at least one transmitting antenna and at least one receiving antenna mounted in spaced relation in the body. Energizing signals are applied to the transmitting antenna to produce electromagnetic energy, a portion of which is received at the receiving antenna after being affected by earth formations surrounding the borehole. In accordance with the disclosed invention, a region of the body is loaded with a dielectric material having a dielectric constant selected to minimize, at the receiving antenna, the effect of spurious transverse magnetic mode components of standing wave electromagnetic energy within the body.