| Patent application number | Description | Published |
|---|
| 20080238428 | Methods of Electromagnetic Logging Using a Current Focusing Receiver - 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. | 10-02-2008 |
| 20080238429 | Receivers and Methods for Electromagnetic Measurements - 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. | 10-02-2008 |
| 20080239875 | Surveying Method Using an Arrangement of Plural Signal Sources - The survey technique for use in a marine environment to survey a subterranean structure includes providing an arrangement of plural signal sources in a body of water to produce corresponding signals. The signals of the signal sources in the arrangement are set to cause reduction of at least one predetermined signal component in data received by a receiver in response to the signals. | 10-02-2008 |
| 20080281667 | Method and Apparatus to Automatically Recover Well Geometry from Low Frequency Electromagnetic Signal Measurements - A technique that is usable with a well includes providing a model so predict measurements that are received by receivers due to transmission by sources baaed on estimated positions of the receivers relative to sources. The estimated positions each have at least two dimensions. At least some of the receivers and the sources are located in the well. On a computer, the estimated positions are automatically refined based on a comparison of the predicted measurements and actual measurements that are obtained by the receivers. | 11-13-2008 |
| 20090001985 | Methods for Electromagnetic Measurements and Correction of Non-Ideal Receiver Responses - A method for determining formation electrical properties includes deploying one or more receivers for electromagnetic logging; obtaining measurement data indicative of the formation electrical properties using the deployed receivers; correcting the measurement data for receiver imperfection; and inverting the corrected measurement data to obtain one or more parameters of formation electrical properties. | 01-01-2009 |
| 20090001986 | SYSTEMS AND METHODS FOR CALIBRATING AN ELECTROMAGNETIC RECEIVER - 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. | 01-01-2009 |
| 20090005992 | Method and System for Removing Effects of Conductive Casings and Wellbore and Surface Heterogeneity in Electromagnetic Imaging Surveys - Characterizing a reservoir with electromagnetic imaging surveys includes normalizing measured voltage data by transmitter moment, sorting the normalized voltage data into common receiver profiles, densely resampling transmitter locations using common positions for the receiver profiles, coarsely resampling the data at discreet transmitter locations, defining a starting model for inversion, weighting the data by a factor, converting the normalized voltage data to ratios, calculating a conductivity image using a ratio inversion method, and verifying that an inversion has converged and the image is geologically reasonable. The image can then be displayed. The invention can be used for cross-well, surface-to-borehole, and borehole-to-surface measurements by which the effects of steel casing are reduced. | 01-01-2009 |
| 20090091328 | Determining correction factors representing effects of different portions of a lining structure - To determine effect on a magnetic field caused by a lining structure in a wellbore, an array may be deployed into the wellbore lined with the lining structure. The array comprises a plurality of sensors including sensor A configured to operate as a transmitter, sensor B configured to operate as either a transmitter or a receiver, and sensor C configured to operate as a receiver. The array measures magnetic fields using sensor B as a receiver and sensor C in response to activation of sensor B as a transmitter and sensor A. A plurality of lining structure correction factors can be calculated based on the measured magnetic fields, based on the reciprocity of the sensors. | 04-09-2009 |
| 20090128138 | METHOD FOR CORRECTING MAGNETIC BASED ORIENTATION MEASUREMENTS FOR LOCAL BIASING FIELDS - A method of determining an orientation of a data acquisition system deployed on a seafloor includes measuring horizontal magnetic fields using detectors on the data acquisition system while the data acquisition rotates and descends to the seafloor or rises from the seafloor. Resting horizontal magnetic fields are measured after the data acquisition system is on the seafloor. A heading of the data acquisition system on the seafloor may be determined based on maximum and minimum horizontal magnetic fields measured during the descent and the resting horizontal magnetic fields. | 05-21-2009 |
| 20090132166 | Processing Measurement Data in a Deep Water Application - To process subterranean survey data, measurement data is collected by a receiver positioned in deep water, where the collected measurement data is responsive to signals emitted by at least one signal source located at or near an air-water interface of the body of water. The measurement data is processed to reduce a predetermined signal component. | 05-21-2009 |
| 20090157316 | METHOD AND SYSTEM FOR REMOVING EFFECTS OF CONDUCTIVE CASINGS AND WELLBORE AND SURFACE HETEROGENEITY IN ELECTROMAGNETIC IMAGING SURVEYS - Characterizing a reservoir with electromagnetic imaging surveys includes normalizing measured voltage data by transmitter moment, sorting the normalized voltage data into common receiver profiles, densely resampling transmitter locations using common positions for the receiver profiles, coarsely resampling the data at discreet transmitter locations, defining a starting model for inversion, weighting the data by a factor, converting the normalized voltage data to ratios, calculating a conductivity image using a ratio inversion method, and verifying that an inversion has converged and the image is geologically reasonable. The image can then be displayed. The invention can be used for cross-well, surface-to-borehole, borehole-to-surface, and single-well (borehole-to-borehole) measurements by which the effects of steel casing are reduced. | 06-18-2009 |
| 20090217074 | TIME SYNCHRONIZATION IN UNITS AT DIFFERENT LOCATIONS - To synchronize units of a formation evaluation/drilling operation evaluation system, a time delay associated with a communications link between a master unit and a slave unit of the formation evaluation/drilling operation evaluation system is determined. The master unit has a master time clock that provides universal time. The time delay associated with the communications link is used to enable synchronization of time provided by a slave time clock in the slave unit to the universal time. | 08-27-2009 |
| 20090281731 | Characterizing at Least One Property of a Liner that Lines a Well - Impedances of an electromagnetic (EM) coil positioned in a well lined with an electrically conductive liner are determined. The impedances correspond to plural frequencies of operation of the EM coil. Based on the impedances of the EM coil corresponding to the plural frequencies, an attenuation factor associated with the electrically conductive liner is determined. | 11-12-2009 |
| 20100013485 | SURVEYING USING VERTICAL ELECTROMAGNETIC SOURCES THAT ARE TOWED ALONG WITH SURVEY RECEIVERS - A system to perform a marine subterranean survey includes at least one vertical electromagnetic (EM) source and at least one EM receiver to measure a response of a subterranean structure that is responsive to EM signals produced by the vertical EM source. At least one tow cable is used to tow the EM source and EM receiver through a body of water. | 01-21-2010 |
| 20100102821 | SURVEYING METHOD USING AN ARRANGEMENT OF PLURAL SIGNAL SOURCES - A survey technique for use in a marine environment to survey a subterranean structure includes providing an arrangement of plural signal sources in a body of water to produce corresponding signals. The signals of the signal sources in the arrangement are set to cause reduction of at least one predetermined signal component in data received by a receiver in response to the signals. | 04-29-2010 |
| 20100121579 | PROCESSING MEASUREMENT DATA THAT INVOLVES COMPUTING A DERIVATIVE OF THE MEASUREMENT DATA THAT REPRESENTS A SUBTERRANEAN STRUCTURE - To process measurement data representing a subterranean structure, a derivative of the measurement data collected by at least one survey receiver is computed, with respect to frequency. A response representing the subterranean structure is then computed based on the derivative of the measurement data, where the response contains an air-wave component that has been suppressed due to computing the derivative of the measurement data relative to at least another component that is sensitive to the subterranean structure. | 05-13-2010 |
| 20100231220 | SYSTEMS AND METHODS FOR ELECTROMAGNETIC DETECTION OF A FORMATION ANOMALY FROM A NEAR BIT LOCATION WHILE DRILLING - A drill string is disposed in the borehole having a BHA and a drill bit advancing the borehole. Among other BHA components, including a telemetry unit and a data acquisition unit, in a surface-to-borehole configuration a receiver (or receiver array) is positioned immediately proximate the drill bit in the borehole, while a source (or source array) is positioned at the Earth's surface. Alternatively, in a borehole-to-surface configuration the source may be positioned immediately proximate the drill bit in the borehole while a receiver (or receiver array) is positioned at the surface. The surface-to-borehole, or borehole-to-surface, system enables an electromagnetic look about while drilling operations are underway. | 09-16-2010 |
| 20100308832 | Determining Correction Factors Representing Effects of Different Portions of a Lining Structure - To determine effect on a magnetic field caused by a lining structure in a wellbore, an array may be deployed into the wellbore lined with the lining structure. The array comprises a plurality of sensors including sensor A configured to operate as a transmitter, sensor B configured to operate as either a transmitter or a receiver, and sensor C configured to operate as a receiver. The array measures magnetic fields using sensor B as a receiver and sensor C in response to activation of sensor B as a transmitter and sensor A. A plurality of lining structure correction factors can be calculated based on the measured magnetic fields, based on the reciprocity of the sensors. | 12-09-2010 |
| 20100321024 | DERIVING AN ELECTROMAGNETIC FIELD IN ONE DIRECTION BASED ON MEASUREMENT DATA OF ONE OR MORE SENSING ELEMENTS FOR MEASURING AN ELECTROMAGNETIC FIELD IN ANOTHER DIRECTION - A survey module includes at least one sensing element to measure a first electromagnetic (EM) field along a first direction, and circuitry to derive a second EM field along a second, different direction based on the first EM field. | 12-23-2010 |
