Abstract: Methods and systems for obtaining an electrical impedivity and/or resistivity image of a subterranean formation are provided. The electrical impedivity and/or resistivity image can be obtained by determining first formation impedivity data and second formation impedivity data. The first formation impedivity data can be based on a component of the measured impedance data orthogonal a downhole fluid impedance. The second formation impedivity data can be based on an amplitude of the measured impedance data. A combined formation impedivity data can be obtained by combining a portion of the first formation impedivity data based on a first formation impedivity determination process with a portion of the second formation impedivity data based on a second formation impedivity determination process. The electrical impedivity and/or resistivity image of the subterranean formation can then be obtained by using the combined formation impedivity data.

Abstract: A system and method for imaging properties of subterranean formations in a wellbore is provided. The system comprises a formation sensor for collecting currents injected into the subterranean formations, the formation sensor positionable on a downhole tool deployable into the wellbore. The system comprises a controller for controlling the formation sensor and a formation imaging unit. The formation imaging unit comprises a current management unit for collecting data from the currents injected into the subterranean formations, the currents having at least two different frequencies. The formation imaging unit comprises a drilling mud data unit for determining at least one drilling mud parameter, a formation data unit for determining at least one formation parameter from the collected data, and an inversion unit for determining at least one formation property by inverting the at least one formation parameter.

Abstract: Methods and systems for obtaining an electrical impedivity and/or resistivity image of a subterranean formation are provided. The electrical impedivity and/or resistivity image can be obtained by determining first formation impedivity data and second formation impedivity data. The first formation impedivity data can be based on a component of the measured impedance data orthogonal a downhole fluid impedance. The second formation impedivity data can be based on an amplitude of the measured impedance data. A combined formation impedivity data can be obtained by combining a portion of the first formation impedivity data based on a first formation impedivity determination process with a portion of the second formation impedivity data based on a second formation impedivity determination process. The electrical impedivity and/or resistivity image of the subterranean formation can then be obtained by using the combined formation impedivity data.

Abstract: A method, a system, and an apparatus are described for the data acquisition in the well-logging of a borehole wall during the investigation of formation properties. Data acquisition is conducted by either an adaptive phase compensation processing or a modulus mode processing, both of which use in-phase and out-of-phase current components to obtain current values. Adaptive phase compensation employs a calculation of a phase shift compensation value, which may then be applied to subsequent acquisitions and can be further processed in the generation of an image of the borehole wall.

Abstract: Methods and systems for obtaining an electrical impedivity and/or resistivity image of a subterranean formation are provided. The electrical impedivity and/or resistivity image can be obtained by determining first formation impedivity data and second formation impedivity data. The first formation impedivity data can be based on a component of the measured impedance data orthogonal a downhole fluid impedance. The second formation impedivity data can be based on an amplitude of the measured impedance data. A combined formation impedivity data can be obtained by combining a portion of the first formation impedivity data based on a first formation impedivity determination process with a portion of the second formation impedivity data based on a second formation impedivity determination process. The electrical impedivity and/or resistivity image of the subterranean formation can then be obtained by using the combined formation impedivity data.

Abstract: Methods and systems for obtaining an electrical impedivity and/or resistivity image of a subterranean formation are provided. The electrical impedivity and/or resistivity image can be obtained by determining first formation impedivity data and second formation impedivity data. The first formation impedivity data can be based on a component of the measured impedance data orthogonal a downhole fluid impedance. The second formation impedivity data can be based on an amplitude of the measured impedance data. A combined formation impedivity data can be obtained by combining a portion of the first formation impedivity data based on a first formation impedivity determination process with a portion of the second formation impedivity data based on a second formation impedivity determination process. The electrical impedivity and/or resistivity image of the subterranean formation can then be obtained by using the combined formation impedivity data.

Abstract: A fluid sensor (and method) for determining at least one parameter of a fluid of a wellbore is provided. The fluid sensor has a base positionable in the wellbore, a base electrode operatively positionable in the insulation, and a raised electrode having at least one base portion and at least one raised portion. The base comprises insulation. The base portion is operatively positionable in the insulation. The at least one raised portion is positionable a distance above the base electrode such that a space is defined therebetween for the passage of the wellbore fluid therethrough. A voltage is applied across the base electrode and the raised electrode to generate a current therebetween whereby at least one parameter of the wellbore fluid may be determined. The fluid sensor is deployable into the wellbore via the downhole tool.

Abstract: A system and method for imaging properties of subterranean formations in a wellbore is provided. The system comprises a formation sensor for collecting currents injected into the subterranean formations, the formation sensor positionable on a downhole tool deployable into the wellbore. The system comprises a controller for controlling the formation sensor and a formation imaging unit. The formation imaging unit comprises a current management unit for collecting data from the currents injected into the subterranean formations, the currents having at least two different frequencies. The formation imaging unit comprises a drilling mud data unit for determining at least one drilling mud parameter, a formation data unit for determining at least one formation parameter from the collected data, and an inversion unit for determining at least one formation property by inverting the at least one formation parameter.

Abstract: A method, a system, and an apparatus are described for the data acquisition in the well-logging of a borehole wall during the investigation of formation properties. Data acquisition is conducted by either an adaptive phase compensation processing or a modulus mode processing, both of which use in-phase and out-of-phase current components to obtain current values. Adaptive phase compensation employs a calculation of a phase shift compensation value, which may then be applied to subsequent acquisitions and can be further processed in the generation of an image of the borehole wall.

Abstract: A method, a system, and an apparatus are described for the data acquisition in the well-logging of a borehole wall during the investigation of formation properties. Data acquisition is conducted by either an adaptive phase compensation processing or a modulus mode processing, both of which use in-phase and out-of-phase current components to obtain current values. Adaptive phase compensation employs a calculation of a phase shift compensation value, which may then be applied to subsequent acquisitions and can be further processed in the generation of an image of the borehole wall.

Abstract: A fluid sensor (and method) for determining at least one parameter of a fluid of a wellbore is provided. The fluid sensor has a base positionable in the wellbore, a base electrode operatively positionable in the insulation, and a raised electrode having at least one base portion and at least one raised portion. The base comprises insulation. The base portion is operatively positionable in the insulation. The at least one raised portion is positionable a distance above the base electrode such that a space is defined therebetween for the passage of the wellbore fluid therethrough. A voltage is applied across the base electrode and the raised electrode to generate a current therebetween whereby at least one parameter of the wellbore fluid may be determined. The fluid sensor is deployable into the wellbore via the downhole tool.

Abstract: A method of determining a depth correction for a logging tool that is moved, while suspended from a cable, along a well, the method being of the type in which a measurement of tool depth is performed at the surface at successive instants, the tool comprising at least two sensors suitable for measuring a characteristic of the well at each instant said two sensors being offset longitudinally in the displacement direction of the tool. The method comprises, at each of said instants:determining a first value for tool velocity by intrinsic measurement;determining a second value of the velocity by correlation between information received from the two sensors; andcombining the first and second velocity values to determine a depth correction to be applied to the surface depth measurement.

Abstract: A method for determining the mobility of fluids within earth formations surrounding a borehole. The preferred embodiment of the invention utilizes measured tube wave parameters such as acoustic slowness and attenuation as indicators of formation fluid mobility, and further modifies the results with a mudcake compensated parameter. The mudcake compensated parameter preferably includes a non-zero, finite membrane impedance contribution, and a mudcake elastic deformation contribution. By inputting values for certain mudcake parameters such as mudcake compressional acoustic velocity, shear velocity, density and impedance, the invention generates an improved quantitative estimate for tube wave derived mobility or permeability.

Abstract: According to the method an acoustic transmitter/receiver tool is lowered in measured manner down a borehole. The tool possesses separate transducers for transmitting and receiving sound waves and includes at least one pair of spaced apart transmitter and receiver spacing. As it is lowered, the tool is caused to repetitively transmit sound waves and on each occasion the waveforms of the echoes received by the tool are recorded in relation to the spacing. Fractures are detected by processing portions of the waveforms which are representative of at least one of two different local effects corresponding to fractures, which effects are amplitude peaks due to a local increase in acoustic coupling, and criss-cross patterns due to mode conversion.