Entries |
Document | Title | Date |
20080246485 | Compact underwater electromagnetic measurement system - An underwater EM measurement system, which is substantially smaller, much simpler to use, and more robust than prior systems, is formed as a sensor package integrated into a single pressure vessel includes two magnetic sensors including induction coils disposed substantially horizontally so as to measure fields in orthogonal directions. The package also includes two electric field sensors including electric potential antennas adapted to couple to a water potential via a capacitive electrode having a conducting material and an electrically insulative layer formed of an insulating material. The capacitive electrode has a capacitance to the medium of greater than 1 mF. Preferably, the insulating material is a metal oxide. | 10-09-2008 |
20090134877 | Optimum signal for sea bed logging - Multifrequency electromagnetic signals which may be used in the field of sea bed logging, the signal being optimised for use at a particular site, in order to greatly improve data inversion, and a method for producing the optimum multifrequency signal. | 05-28-2009 |
20090302847 | MULTI-AXIAL ANTENNA AND METHOD FOR USE IN DOWNHOLE TOOLS - Embodiments of a multi-axial antenna system and system for measuring subsurface formations are generally described herein. Other embodiments may be described and claimed. In some embodiments, the multi-axial antenna system comprising at least two co-located coils wound around a torroidal-shaped bobbin. Each coil generates a magnetic field in a mutually orthogonal direction. Signals provided to the coils may be adjusted to simulate a tilted-coil antenna system. | 12-10-2009 |
20100001733 | SENSOR CABLE FOR ELECTROMAGNETIC SURVEYING - A sensor cable for surveying. The sensor cable has a housing, which includes one of more electrodes and a conductive gel surrounding the one or more electrodes. The conductive gel is configured to conduct electrical current to the one or more electrodes and keep the one or more electrodes moist. The housing may also have a membrane surrounding the conductive gel, wherein the membrane is configured to hold the conductive gel in contact with the one or more electrodes and permit electric current to flow between a surrounding medium and the conductive gel. | 01-07-2010 |
20100039114 | Method For Electroseismic Survey Design - A method for designing a controlled-source electromagnetic survey that will discriminate between a defined deep marginal-interest reservoir ( | 02-18-2010 |
20100052686 | Seismic activity detector - A system for detecting precursor seismic electromagnetic waveforms. | 03-04-2010 |
20110210741 | Structure for magnetic field sensor for marine geophysical sensor streamer - A marine electromagnetic sensor cable includes a first jacket covering an exterior of the cable. At least one wire loop is disposed on the exterior of the first jacket. The wire loop is shaped to have a magnetic dipole moment along a selected direction. A contact ring is disposed inside the first jacket to make electrical connection between the at least one wire loop and an associated signal processing circuit disposed inside the first jacket. | 09-01-2011 |
20110227576 | METHOD OF MONITORING BEHAVIOR OF CARBON DIOXIDE IN POROUS AQUIFER BY USING MARINE CONTROLLED-SOURCES ELECTROMAGNETIC SURVEY - A method of monitoring a behavior of carbon dioxide in a stratum by using a marine Controlled-Sources Electromagnetic survey, includes: (S10) collecting a sample of sandstone at a stratum for charging carbon dioxide; (S20) calculating an effective porosity of the collected sample; (S30) measuring an electrical resistivity by saturating the collected rock sample with a pore fluid having a different concentration; (S40) forecasting a change of an electrical resistivity of stratum by charging carbon dioxide; (S50) carrying out a Marine CSEM exploration before and after charging the carbon dioxide separately in each step; and (S60) monitoring a charging behavior of carbon dioxide in stratum by a Marine CSEM exploration. | 09-22-2011 |
20120056623 | Electromagnetic Surface-to-Borehole Look Around Systems and Methods of Monitoring in Horizontal Wells - A method for water monitoring about a deviated well is disclosed. The method includes positioning a series of electromagnetic (EM) receivers in a completed deviated wellbore, said receivers being spaced along substantially the length of the well located in a region of a reservoir to be monitored. The method also includes positioning an electromagnetic (EM) source at a first Earth surface location. Then the EM source is activated for a first survey measurement of the reservoir, and an EM field detected at each EM receiver is recorded. The EM source is moved to a second Earth surface location, and activated for a second survey measurement of the reservoir, and an EM field detected at each EM receiver is recorded. From the first and second survey measurements at each of the receivers, an inversion is performed to determine position of water about (and specifically below) the horizontal well. | 03-08-2012 |
20120112752 | COMBINING DIFFERENT ELECTROMAGNETIC DATA TO CHARACTERIZE A SUBTERRANEAN STRUCTURE - First electromagnetic data is acquired for a subterranean structure using a first survey technique, and second electromagnetic data is acquired for the subterranean structure using a second, different survey technique in which static positioning of at least one electromagnetic source is employed. The first and second electromagnetic data are combined to characterize the subterranean structure. | 05-10-2012 |
20120153958 | METHODS FOR DETERMINING DIELECTRIC PERMITTIVITY SPECTRUM OF UNDERGROUND ROCK FORMATIONS - A method for determining the frequency-dependent dielectric permittivity spectrum of a rock sample, comprising:—defining a series of electromagnetic measurement data comprising at least a first measurement at a frequency from which a substantially frequency-independent value of dielectric permittivity ∈ | 06-21-2012 |
20120161774 | MULTI-COMPONENT MARINE ELECTROMAGNETIC SIGNAL ACQUISITION METHOD - A method for determining a component of electric field response to a time varying electromagnetic field induced in the Earth's subsurface involves measuring magnetic field gradient in at least two orthogonal directions in response to the induced electromagnetic field and determining an electric field response in a direction normal to the magnetic field gradient measurements. A method for determining a component of electric field response of the Earth's subsurface to a time varying electromagnetic field induced in the Earth's subsurface involves measuring electric field response along a substantially closed pattern on at least one of the Earth's surface and the bottom of a body of water and determining an electric field response in a direction normal to the measured electric field response using electric field response measurements made at opposed positions along the closed pattern. | 06-28-2012 |
20130162255 | ELECTROMAGNETIC GEOPHYSICAL SURVEY SYSTEMS AND METHODS EMPLOYING ELECTRIC POTENTIAL MAPPING - The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A calculation module is included and configured to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to a reference potential assumed to be present at a selected electrode for each of the plurality of geophysical survey cables. Each reference potential is assumed to be of a magnitude that is within a tolerance range of a common reference potential. | 06-27-2013 |
20130229184 | Stationary Source for Marine Electromagnetic Surveying - Disclosed are methods and systems for using electromagnetic sources that are substantially stationary in a body of water while electromagnetic field signals are detected with electromagnetic sensors towed through the body of water. An embodiment discloses an apparatus comprising: a vessel; a first electromagnetic source coupled to the vessel and configured to have a dipole moment oriented in a first direction; and a second electromagnetic source coupled to the vessel and configured to have a dipole moment oriented in a second direction, wherein the second direction is generally orthogonal to the first direction. Another embodiment discloses a system comprising: a sensor streamer configured for towing in a body of water, wherein the sensor streamer comprises a plurality of electromagnetic sensors disposed at spaced apart positions; and an electromagnetic source assembly configured for deployment at a substantially stationary position in the body of water. | 09-05-2013 |
20130335089 | THREE DIMENSIONAL ANTENNA SYSTEM FOR MEASURING OSCILLATORY ELECTRIC FIELD STRENGTHS - A new three dimensional dipole based antenna system is described used to measure oscillatory electric field strengths. The antenna system is connected to an object (a survey platform) that is stationary or moving in an area of interest in air, over land, on water or under water. This invention aims to reduce the influence of noise sources on electric field strength measurements. Such measurements are generally collected as part of prospecting surveys for minerals or hydrocarbons. | 12-19-2013 |
20130335090 | MILD STEEL DIPOLE ANTENNA SYSTEM FOR MEASURING OSCILLATORY ELECTRIC AND MAGNETIC FIELD STRENGTHS - A one dimensional dipole based antenna system is described used to measure oscillatory electric and magnetic field strengths and the rate of change of the magnetic field strength. The system relies on paramagnetic mild steel for selected dipole system components to decrease the sensitivity to high frequency oscillatory magnetic signals progressively above a certain frequency in the range of | 12-19-2013 |
20140111209 | METHODS AND SYSTEMS FOR ANALYZING FORMATION PROPERTIES WHEN PERFORMING SUBTERRANEAN OPERATIONS - A method of analyzing a subterranean formation is disclosed. A first signal is transmitted from a transmitter to the formation and a second signal which is a reflection of the first signal is received. A third signal, which is the second signal reversed in time, is then transmitted to the formation. A fourth signal which is a reflection of the third signal from the formation is then received and monitored. | 04-24-2014 |
20140152312 | STIMULATING PRODUCTION FROM OIL WELLS USING AN RF DIPOLE ANTENNA - A system emplaced in a subsurface formation configured to produce radio frequency (RF) fields for recovery of thermally responsive constituents includes coaxially disposed inner and outer conductors connected at an earth surface to an RF power source. The inner and outer conductors form a coaxial transmission line proximate said earth surface and a dipole antenna proximate said formation. The inner conductor protrudes from the outer conductor from a junction exposing a gap between the conductors to a deeper position within the formation. The RF power source is configured to deliver, via the conductors, RF fields to the formation. The system also includes at least one choke structure attached to said outer conductor at a distance at least ¼ wavelength above said junction. The choke structure is configured to confine a majority of said RF fields in a volume of said formation situated adjacent to said antenna. | 06-05-2014 |
20140239955 | SYSTEM FOR DETECTING A LOCATION OF A SUBSURFACE CHANNEL - A system for detecting a location of a subsurface channel may include a portable frame and a plurality of magnetic coils supported by the frame. The magnetic coils may be spaced apart from one another and ends of each of the magnetic coil are unobstructed by other of the magnetic coils. | 08-28-2014 |
20140253129 | Silicon Controlled Rectifier Control of Deep Towed Electromagnetic Source - A method and apparatus for generating an electromagnetic (EM) field from a sub-sea source is disclosed. In one embodiment, a sub-sea source includes a step-down transformer coupled to receive a sinusoidal source wave via a tow cable, and is further coupled to output a sinusoidal wave to a silicon-controlled rectifier (SCR) circuit. A control circuit coupled to the SCR circuit is configured to selectively activate various ones of the SCRs therein in order to control a portion of the sinusoidal wave that is rectified. The output current provided by the SCR is determined by the portion of the sinusoidal wave that is rectified thereby. The output current is provided to electrodes coupled to the sub-sea source, and the output current is passed therebetween. The strength of the EM field is based on the output current. | 09-11-2014 |