Patent application number | Description | Published |
20080278171 | Two-Axial Pad Formation Resistivity Imager - A resistivity imaging device injects currents in two orthogonal directions using two pairs of return electrodes and performing impedance measurements of the buttons placed between the returns. | 11-13-2008 |
20080288171 | DUAL STANDOFF RESISTIVITY IMAGING INSTRUMENT, METHODS AND COMPUTER PROGRAM PRODUCTS - A resistivity imaging apparatus includes: a first sensor electrode disposed on an electrode pad and positioned at a first standoff; a second sensor electrode disposed on the electrode pad and adjacent the first sensor electrode, the second sensor electrode positioned at a second standoff; and a return electrode disposed on the electrode pad, wherein the sensor electrodes and the return electrode are configured for injecting current into a formation and receiving a signal from the formation. Other embodiments, methods and computer program products are disclosed. | 11-20-2008 |
20080303525 | SINGLE-DIPOLE HIGH FREQUENCY ELECTRIC IMAGER - A single-dipole sensor for determining an electrical property of an earth formation, includes a pad consisting essentially of a body and at least one small electrode separated from a large electrode by an insulator; wherein an output of the sensor includes a measurement of an electrical signal through the formation for each small electrode. A method for using the sensor is included, as well as a method for providing images of the earth formation. | 12-11-2008 |
20080303526 | Imaging Based on 4-Terminal Dual-Resistor Voltage Measurements - Measurements made by a four terminal resistivity imaging tool in a borehole using a voltage measurement device with two different input impedances. From the two measurements, formation resistivity is determined with minimal sensitivity to standoff. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. | 12-11-2008 |
20090237084 | Electromagnetic and Magnetostatic Shield to Perform Measurements Ahead of the Drill Bit - A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A pair of receivers on the BHA receive signals that are indicative of formation resistivity and distances to bed boundaries. A time dependent calibration factor or a time-independent calibration factor may be used to combine the two received signals and estimate the distance to bed boundaries that are unaffected by the drill conductive body. Further improvement can be obtained by using copper shielding. | 09-24-2009 |
20090240435 | Method and apparatus for eliminating drill effect in pulse induction measurements - A method and apparatus provide a time-dependent calibration to essentially eliminate pipe effect in pulse-induction logging while drilling. Use of two receivers to provide calibration and measurement information allows determination of formation properties in a downhole environment while eliminating the effect of tool effects. | 09-24-2009 |
20090243619 | FOUR-TERMINAL ELECTRIC IMAGER FOR RESISTIVE MUDS WITH LOCALIZED CURRENT CONTROL - An apparatus for imaging a subsurface material traversed by a borehole, the apparatus including an imaging pad deployed by a logging instrument, the pad including a plurality of measuring sets, each measuring set including a first current injector electrode, a second current injector electrode, a pair of sensor electrodes disposed between the first current injector electrode and the second current injector electrode, and an output for coupling to an electronics unit adapted for producing the imaging of the subsurface material. | 10-01-2009 |
20090292471 | Statistical Correction for Standoff in Two-Terminal Imager Operating in Oil-Based Mud - An apparatus, method and computer-readable medium for estimating a resistivity property of an earth formation in a borehole filled with oil-based mud. The method includes conveying a logging tool into a borehole; measuring a plurality of impedance values of the earth formation, each of the plurality of impedance values being obtained at one of a plurality of measure electrodes on the logging tool; determining a coefficient related to an electrical property of the mud from a plurality of pairs of impedance values; estimating the resistivity property of the formation from the determined coefficient; and recording the resistivity property on a suitable medium. | 11-26-2009 |
20100019771 | Multi-Resolution Borehole Resistivity Imaging - An apparatus, method and computer-readable medium for obtaining a resistivity image of an earth formation. The apparatus includes a downhole assembly configured to be conveyed in a borehole penetrating the earth formation; a plurality of sensor electrodes on the downhole assembly, each of the plurality of sensor electrodes having a different capacitance to a wall of the borehole; and at least one processor configured to: (i) process measurements using each of the sensor electrodes; (ii) process a subset of the measurements substantially unaffected by the different capacitances to produce an image of the borehole wall; and (iii) record the image on a suitable medium. | 01-28-2010 |
20100023268 | Multi-resolution Borehole Resistivity Imaging - An apparatus, method and computer-readable medium for obtaining a resistivity image of an earth formation. The apparatus includes a downhole assembly configured to be conveyed in a borehole penetrating the earth formation; a plurality of sensor electrodes on the downhole assembly, at least one of the electrodes having a different area than another of the electrodes; and at least one processor configured to: (i) process measurements using each of the sensor electrodes; (ii) process a subset of the measurements substantially unaffected by the different capacitances to produce an image of the borehole wall; and (iii) record the image on a suitable medium. | 01-28-2010 |
20100039115 | SYSTEM AND METHOD FOR MEASURING RESISTIVITY OF AN EARTH FORMATION WITH CORRECTION FOR MUD ELECTRICAL PROPERTIES - A method for measuring a resistivity parameter of an earth formation is provided. The method includes: conveying a measurement current from at least one measurement electrode into the formation, the at least one measurement electrode having a potential; receiving the measurement current by at least one return electrode; and estimating a resistivity parameter from a measurement value selected from at least one of the measurement current and the potential, the resistivity parameter based on (i) an impedance calculated from the measurement value and (ii) a correction factor calculated from a plurality of measurement values related to a conductivity of a fluid in a borehole and a dielectric constant of the fluid in the borehole. A system for measuring a resistivity parameter of an earth formation is also provided. | 02-18-2010 |
20100097065 | Method and apparatus for while-drilling transient resistivity measurements - Structure for deep MWD resistivity measurements suitable for both geo-steering and measurements ahead of the drill bit is disclosed. The structure is capable of extracting information about resistivity of formation in the presence of conductive drill. In one embodiment, ahead-of-bit sensing is achieved via transient electromagnetic measurements when current is switched off in the transmitter loop and the transient signal is measured in the receiver loops placed at some distances from the receiver. To reduce a parasitic effect of the currents in the drill three-coil bucking system with magnetic nonconductive shield in combination with a highly conductive copper shield are applied. Specifically, a short (less than 1 m) copper cover and short (less than 0.2 m) ferrite cover are placed in the vicinity of transmitting and receiving coils. A bucking operation followed by an inversion is performed on received signals to obtain data reflecting parameters of the surrounding subsurface formations. | 04-22-2010 |
20100097068 | Method and apparatus for borehole wall resisitivity imaging with full circumferential coverage - A logging tool for performing resistivity measurements on the sidewall of a borehole in an earth formation is provided with a circumferential series of evenly-spaced measurement electrodes providing complete circumferential coverage of resistivity measurements. In one embodiment, the measurement electrodes are carried on a conductive pad circumferentially surrounding an elongate mandrel or tubular. The conductive pad is held at a voltage adapted to focus measurement current into the sidewall of the borehole. Preferably, the pad has dimensions relative to the measurement electrodes and a standoff distance between the measurement electrodes and said borehole wall to effectively focus the measurement current into the borehole wall. In accordance with one aspect of the invention, the measurement electrodes are spaced apart by a distance that is less than the width of each measurement electrode, thereby ensuring full circumferential resolution. | 04-22-2010 |
20100109672 | Transient EM for Geosteering and LWD/Wireline Formation Evaluation - A transmitter on an instrument is used to induce currents in an earth formation when it is turned on or off. A Fourier transform is applied to transient measurements made in the receivers. A multifrequency focusing of the transformed data is used for applications like determination of a distance to an interface in the formation, controlling the drilling direction, determination of formation resistivities and formation strike directions. | 05-06-2010 |
20100109905 | Deep MWD Resistivity Measurements Using EM Shielding - Structure for deep MWD resistivity measurements suitable for both geo-steering and measurements ahead of the drill bit is disclosed. Alternating current is transmitted through a loop and an induction signal is measured by a two-coil bucking receiving system placed at some distance from the transmitter. To further reduce a parasitic effect of the currents in the pipe, a conductive copper shield wrapping around the pipe is used. The length of the shield is about one and one-half to two times longer than the longest transmitter/receiver spacing of the structure. The transmitter/receiver system is located in the center of the described electromagnetic shield. | 05-06-2010 |
20100125439 | Method of Deep Resistivity Transient Measurement While Drilling - A transient electromagnetic signal is recorded in an earth formation in the presence of a pipe having a finite conductivity. A portion of the signal dominated by the pipe signal is analyzed to determine a functional representation, extrapolated back to a time interval where the formation signal is present and subtracted from the recorded signal to provide a corrected signal. | 05-20-2010 |
20100134111 | Method of Measuring and Imaging RXO (Near Wellbore Resistivity) Using Transient EM - A transient electromagnetic wave is generated using an electromagnetic instrument in a borehole. An apparent resistivity is estimated using a received signal responsive to the generated wave and further used to estimate a resistivity property of a fluid in the borehole. | 06-03-2010 |
20100213943 | METHOD FOR ACCENTUATING SIGNAL FROM AHEAD OF THE BIT - A method for estimating a property of a portion of an earth formation ahead of a borehole penetrating the formation, the method includes: conveying a logging tool through the borehole; receiving one or more first signals from a previous depth of the logging tool; constructing a model of the earth formation using the one or more first signals; predicting one or more second signals from the portion of the earth formation ahead of the borehole using the model; receiving one or more third signals from the portion of the earth formation ahead of the borehole; calculating a difference between the one or more third signals and the one or more second signals; and estimating the property from the difference. | 08-26-2010 |
20100286915 | Monitoring Reservoirs Using Array Based Controlled Source Electromagnetic Methods - Electrical property contrast difference maps of the subsurface formations may be produced using surface and/or near surface array of transmitters and receivers tuned to emit and receive electromagnetic (EM) signals. The electrical property may be resistivity or conductivity. The maps may be time based. A time based trend change may be used to predict the location and movement of fluids within the hydrocarbon bearing or any other subsurface zones where resistivity and/or conductivity values of the fluids within these zones change over time. | 11-11-2010 |
20100295548 | METHODS AND APPARATUS FOR PROVIDING COMPLIMENTARY RESISTIVITY AND STANDOFF IMAGE - A method for presenting a formation property to a user includes estimating an initial property of the formation using a tool conveyed in a borehole and estimating a relationship between the tool and the formation based on information received from the tool. The method also includes presenting the user a first output based at least in part on the initial property and presenting a second output based at least in part on the relationship proximate the first output. | 11-25-2010 |
20110025335 | METHOD AND APPARATUS FOR GALVANIC MULTI-FREQUENCY FORMATION RESISTIVITY IMAGING - A formation measurement and processing technique which reduces the effects of standoff between a resistivity tool and a borehole wall where the resistivity tool utilizes capacitive coupling between the tool and the formation to obtain resistivity data useful to generate a resistivity image of the formation. Reduction of standoff effects is achieved through the use of multi-frequency, phase sensitive measurements to identify a measured resonance frequency that may be used to produce an image that utilizes measurements least affected by the tool standoff and unknown or unspecified inductance of the tool. Reduction of standoff effects are the most pronounced in the case of the low resistivity formations and oil-based, low-conductive drilling fluids. | 02-03-2011 |
20110063949 | TDEM FORWARD FOCUSING SYSTEM FOR DOWNHOLE USE - A method and apparatus for estimating a parameter of interest of an earth formation ahead of a carrier within borehole. The method including estimating one or more functions based on received signals that may reduce the sum of the signals received by a first receiver, and estimating the parameter of interest based on signals received by one or more additional receivers by applying the one or more functions and, if necessary, a defocusing factor, such that reception of information from downhole of a selected downhole location is enhanced relative to reception of information uphole from the selected location. The apparatus including two or more transmitters, two or more receivers, and a processor to estimate one or more functions, and, based on these functions, the parameter of interest. | 03-17-2011 |
20110156708 | CONCENTRIC BUTTONS OF DIFFERENT SIZES FOR IMAGING AND STANDOFF CORRECTION - Disclosed is a method of estimating a property of an earth formation penetrated by a borehole. The method includes: disposing into the borehole a sensor having a plurality of return electrodes and at least one transmitter electrode disposed in a concentric arrangement; injecting a first current of a first frequency into the formation by applying an alternating current voltage between first selected ones of the plurality of return electrodes and the at least one transmitter electrode; injecting a second current of a second frequency into the formation by applying an alternating current voltage between second selected ones of the plurality of return electrodes and the at least one transmitter electrode; measuring effective impedance for each of the currents; and estimating the property using the measurements of the effective impedance for each of the currents; wherein the estimating compensates for an influence of standoff distances of the sensor on the measurements | 06-30-2011 |
20110257886 | Three-Coil System With Short Nonconductive Inserts for Transient MWD Resistivity Measurements - A three-coil bucking system is used for determination of a formation resistivity property ahead of the drill bit. The conductive drill pipe is provided with non-conductive inserts in the proximity of at least one transmitter and at least two receivers. Transient electromagnetic signals are processed to give the estimate of the resistivity property and for geosteering. | 10-20-2011 |
20120059586 | DTEM With Short Spacing for Deep, Ahead of the Drill Bit Measurements - A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A processor estimates the distance to a resistivity interface using a signal produced by a receiver on the BHA. The transmitter-receiver distance may be less than 1 m. The estimation of the distance is done in real time using a thin conductive sheet approximation. | 03-08-2012 |
20120209527 | CONCENTRIC BUTTONS OF DIFFERENT SIZES FOR IMAGING AND STANDOFF CORRECTION - Disclosed is a method of estimating a property of an earth formation penetrated by a borehole. The method includes conveying a carrier through the borehole and performing a plurality of electrical measurements on the formation using a sensor disposed at the carrier and having a plurality of electrodes disposed in a concentric arrangement wherein a standoff distance between the sensor and a wall of the borehole has an influence on each electrical measurement in the plurality of electrical measurements. The method further includes determining an impedance for each electrical measurement in the plurality of electrical measurements and inputting the determined impedances into an artificial neural network implemented by a processor. The artificial neural network outputs the property wherein the outputted property compensates for the influence of sensor standoff distance on each electrical measurement in the plurality of electrical measurements. | 08-16-2012 |
20120209528 | Inversion-Based Method to Correct for the Pipe Residual Signal in Transient MWD Measurements - An apparatus and method for reducing a pipe residual signal from transient signals in an induction tool having a metallic pipe with finite, non-zero conductivity in a borehole penetrating an earth formation. The apparatus may include a transient electromagnetic (TEM) signal transmitter, at least one receiver configured to generate an output signal in response to the TEM signal, and at least one processor for estimating an updated model with an improved estimate of the resistivity property. The updated model may be estimated based on a difference between a simulated signal from an initial model and the output signal. The difference may be represented by a set of basis functions. The method includes using the apparatus. | 08-16-2012 |
20130013210 | ELECTRICAL IMAGER OPERATING IN OIL-BASED MUD AND LOW RESISTIVE FORMATION - This disclosure relates to apparatuses and methods for reducing current leakage between a measure electrode and a logging tool body during borehole investigations in an earth formation involving electric current and non-conductive drilling fluid. The apparatus may include one or more transmitters disposed on a pad body, configured to inject an electric current into the earth formation, and coupled to the mandrel and one or more measure electrodes. The measure electrodes may be configured to receive current from the formation and coupled to a back plate of the pad body. The apparatus may be configured to maintain a selected ratio between pad body to logging tool body impedance and transmitters to logging tool body impedance sufficient to reduce current leakage between the earth formation and the logging tool body. The transmitter/mandrel and measure electrode/back plate may be electrically isolated from one another. The method may include using the apparatus. | 01-10-2013 |
20130024120 | FORMATION RESISTIVITY IMAGER REDUCED LEAKAGE TO MANDREL - A method of estimating a parameter of a formation contacting a borehole with an instrument that includes a mandrel and a pad includes providing a measurement voltage to the pad; applying a biasing voltage to the mandrel while the measurement voltage is applied to the pad; measuring a received current during at least a portion of time the measurement voltage is provided; and estimating the parameter based on the received current. | 01-24-2013 |
20140288834 | FAST INVERSION OF MWD TRANSIENT EM DATA EXCITED BY A PULSE OF AN ARBITRARY SHAPE - A system and method of estimating properties of a subsurface formation are described. The method includes transmitting an excitation current pulse into the formation, receiving an induced pulse used to generate input data, and performing an inversion on the input data using a lookup table based on a shape of the excitation current pulse to estimate the properties of the subsurface formation. | 09-25-2014 |
20140318783 | Method of Real Time Monitoring of Well Operations Using Self-Sensing Treatment Fluids - Downhole conditions in a wellbore may be monitored in real time by pumping into the well a sensing treatment fluid which includes a piezoelectric or piezoresistive material and measuring changes in electrical resistivity within the wellbore. The monitoring in real time of the piezoelectric or piezoresistive material enhances the integrity of the wellbore during the setting of the treatment fluid as well as during the lifetime of the well. | 10-30-2014 |