Abstract: A system and method for monitoring underground drilling in which vibration is monitored by creating a model of the drill string using finite element techniques or finite difference techniques and (i) predicting vibration by inputting real time values of operating parameters into the model, and then adjusting the model to agree with measured vibration data, (ii) predicting the weight on bit and drill string and mud motor speeds at which resonance will occur, as well as when stick-slip will occur, so that the operator can avoid operating regimes that will result in high vibration, (iii) determining vibration and torque levels along the length of the drill string based on the measured vibration and torque at one or more locations, (iv) determining the remaining life of critical components of the drill string based on the history of the vibration to which the components have been subjected, and (v) determining the optimum drilling parameters that will avoid excessive vibration of the drill string.

Abstract: A laboratory NMR methodology (and corresponding laboratory apparatus) defines a sample volume. The method stores downhole tool data corresponding to a hydrocarbon-bearing sample collected from a given subsurface formation. The downhole tool data includes parameters pertaining to magnetic fields used by a downhole tool during a suite of NMR measurements of the given subsurface formation. The sample is positioned in the sample volume of the laboratory apparatus, which applies a static magnetic field in the sample volume. Furthermore, the laboratory apparatus applies a suite of NMR measurements to the sample volume to thereby determine a property of the sample. The NMR measurements of the suite each include a pulse sequence of oscillating magnetic field in conjunction with a pulsed-mode gradient field. The pulsed-mode gradient field is based on the stored downhole tool data corresponding to the sample. A laboratory NMR methodology for optimizing downhole NMR measurements is also described.

Abstract: A method for evaluating inflow or outflow in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density may be measured during static conditions or while drilling and may be further processed to compute a density of an inflow constituent in the annulus. Changes in the computed interval density with time may be used as an indicator of either an inflow event or an outflow event.

Abstract: A method identifying a wellbore volume change while drilling a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The wellbore volume change may include, for example, a borehole washout or a borehole pack-off. The pressure measurements may then be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval densities may be measured while drilling and may be further evaluated as an indicator of a wellbore volume change.

Abstract: Downhole drilling vibration analysis uses acceleration data measured in three orthogonal axes downhole while drilling to determine whether drilling assembly's efficiency has fallen to a point where the assembly needs to be pulled. In real or near real time, a downhole tool calculates impulse in at least one direction using the measured acceleration data over an acquisition period and determines whether the calculated impulse exceeds a predetermined acceleration threshold for the acquisition period. If the impulse exceeds the threshold, the tool pulses the impulse data to the surface where the calculated impulse is correlated to efficiency of the assembly as the drillstring is used to drill in real time. Based on the correlation, operators can determine whether to pull the assembly if excessive impulse occurs continuously over a predetermined penetration depth.

Abstract: Downhole drilling fluid measurements are made as a function of time or as a function of depth. A change in the downhole drilling fluid measurements is correlated to a feature of a formation penetrated by a drill bit or to a feature of fluids in the formation. The downhole drilling fluid measurements may include density, photoelectric factor, hydrogen index, salinity, thermal neutron capture cross section (Sigma), resistivity, slowness, slowing down time, sound velocity, and elemental composition. The feature may include fluid balance, hole-cleaning, a kick, a shallow water flow, a formation fluid property, formation fluid typing, geosteering, geostopping, or an environmental correction. A downhole system has a measurement-while-drilling tool or a logging-while-drilling tool and a processor capable of obtaining the downhole drilling fluid measurements and correlating the change in the downhole drilling fluid measurements.

Abstract: Mud pulse telemetry. The various embodiments are directed to methods and systems of encoding data in a mud pulse telemetry system, where at least a portion of the data is encoded the time between pressure transitions. Moreover, the various embodiments are directed to detection methods and systems that detect the pressure transitions at the surface.

Abstract: Control system (40) for a machine for digging and/or drilling earth, wherein the machine for digging and/or drilling earth (10) comprises a digging head (11) arranged to dig the soil, a flexible load-bearing element (12) arranged to support the digging head (11) during normal operation, at least a first (13) and a second winch (14), each of which in turn comprises a drum (32, 33) about which at least part of the flexible load-bearing element (12) can be wound, and a motor (30, 31) arranged to actuate the drum (32, 33); the control system (40) has an electronic control unit (43) adapted for controlling the movement of the winches (13,14), and velocity sensor means arranged in each branch of load-bearing cable (12) coming out from the winches (13,14) adapted for monitoring the movement of such a load-bearing cable.

Abstract: A time-dependent magnetic field and/or flux is implemented to determine information related to geological formations within the geologic volume of interest. Such information may include one or more of location, boundary or shape, pressure, faults, lithology, strength, and/or other information. A source of the time-dependent magnetic field and/or flux may leverage the operation of an excavation tool used to excavate a hole at or near the geologic volume of interest in order to generate the magnetic field and/or flux. A plurality of different sources may be used to generated the magnetic field and/or flux.

Abstract: The present invention provides a computer-implemented software tool that is adapted to listen continuously to data streams from a drilling operation and to process the data to generate a situation description for a current drilling situation in a form useful for automated continuous matching with a set of past cases stored in a knowledge database. The invention implements a case-based reasoning (CBR) approach to match the current drilling situation as defined by the situation description with one or more stored past cases having a degree of similarity above a predetermined threshold level. Matching cases are displayed to the drilling engineer as symbols on a case “radar”, allowing the drilling engineer to retrieve and view the details of a past case and take appropriate action based on drilling advice provided within the past case.

Abstract: Apparatus for identifying rock properties in real-time during drilling, are provided. An example of an embodiment of such an apparatus includes one or more acoustic sensors positioned to detect drill sounds emanating from the drill bit and the rock encountered during drilling operations, connected to select components of a drilling rig to maximally pick up the drill sounds of the drill bit engaging rock during drilling operations. The apparatus also includes an inductive telemetry, wireless telemetry, or wired transmitting system. The apparatus also includes a computer to analyze the acoustic signals received from the acoustic sensors through the respective transmitting system for lithology type and petrophysical properties.

Abstract: Methods, computer programs, and systems for detecting at least one downhole condition are disclosed. Forces are measured at a plurality of locations along the drillstring. The drillstring includes a drillpipe. At least one of the forces is measured along the drillpipe. At least one downhole condition is detected based, at least in part, on at least one measured force.

Abstract: An electronic control system for drilling devices, includes at least one pair of data-processing units (2a, 2b); a plurality of data-exchange lines, connected to the data-processing units (2a, 2b) for transmission of signals from and to control devices (4a-4c) of the drilling device; and accessories (5, 9) proper to the drilling device. Each of the data-processing units (2a, 2b) is redundant by the others with one and the same level of hierarchy, and all the data-processing units (2a, 2b) are connected to all the control devices (4a-4c) and to the accessories (5, 9) proper to the drilling device through the electronic data-exchange lines that are redundant in a number equal to the multiplicity of the data-processing units (2a, 2b).

Abstract: A method for planning a wellbore, the method including defining drilling data for drilling a segment of a planned wellbore and identifying a risk zone in the segment. Additionally, the method including determining an expected fluid loss for the risk zone and selecting a solution to reduce fluid loss in the risk zone. Furthermore, a method for treating drilling fluid loss at a drilling location, the method including calculating a drilling fluid loss rate at the drilling location, classifying the drilling fluid loss based on the drilling fluid loss rate, and selecting a solution based at least in part on the classifying.

Abstract: Disclosed is a method for estimating a pore pressure of an earth formation penetrated by a borehole and an associated uncertainty. The method includes: conveying a carrier through the borehole; performing formation measurements relating to porosity at a plurality of depths in the borehole using a downhole tool coupled to the carrier; defining a first depth interval and a second depth interval deeper than the first depth interval, the first depth interval comprising a first set of formation measurement points and the second depth interval comprising a second set of formation measurement points; establishing a plurality of trendlines of depth versus porosity-related measurements using a processor with each trendline in the plurality of trendlines extending from a point in the first depth interval through a point in the second depth interval; and calculating a pore pressure line and associated uncertainty using the plurality of trendlines.

Abstract: A method evaluating a cuttings density while drilling a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density may be measured while drilling and may be further processed to compute a cuttings density in the annulus. Moreover, changes in the computed interval density with time while drilling may be used as an indicator of a change in cuttings density.

Abstract: A prog analysis and execution system and method. The system includes a computer control system, an interface engine in communication with the computer control system, the interface engine being configured to receive prog information, and an action item development engine in communication with the control system, the action item development engine being configured to analyze received prog information and to determine corresponding action items. The system further includes a sensor engine in communication with the computer control system, the sensor engine being configured to receive input from at least one sensor for use in controlling a well drilling operation, and an operational equipment engine in communication with the computer control system, the operational equipment engine being configured to receive input from the computer control system and to control the well drilling operation in accordance with the determined action items in the prog.

Abstract: A method for attenuating pump noise in a wellbore drilling telemetry system includes spectrally analyzing measurements of a parameter related to operation of a pump used to move drilling fluid through the drilling system. Synthetic spectra of the parameter are generated based on a number of pumps in the pump system and a selected number of harmonic frequencies for each pump. Which of the synthetic spectra most closely matches the spectrally analyzed parameter output is determined. The most closely matching synthetic spectrum is used to reduce noise in a signal detected proximate the Earth's surface transmitted from a part of the drilling system disposed in a wellbore.

Abstract: A method for predicting mechanical properties of a transverse isotropic region of a rock formation traversed by a well bore including running a logging tool in the well bore; the mass percentages of minerals present in the rock formation surrounding the well bore are measured with the logging tool. The density of the minerals present in the rock formation surrounding the well bore is determined. The porosity of the rock formation surrounding the well bore is measured. From the porosity and the measured mass percentages and density of the minerals, all the transverse isotropic elastic coefficients of the rock formation are determined in real time.

Abstract: A system and computer assisted method to fractionate an oil or other well using a user moveable and rotatable three dimensional model of a lateral pay zone for a directionally drilled well, and other information relative to the lateral pay zone, enabling accurate identification of fractionation zones, accurate placement of well perforating guns, and accurate insertion of fractionation plugs to maximize production of the well, while additionally enabling the three dimensional model of the lateral pay zone to be viewable and updatable by on site uses at the location of the fractionation and by remote users as events occur, in some cases, in providing updates in less than 1 minute.

Abstract: Disclosed is a method for estimating downhole lateral vibrations a drill tubular disposed in a borehole penetrating the earth or a component coupled to the drill tubular. The method includes rotating the drill tubular to drill the first borehole and performing a plurality of measurements in a time window of one or more parameters of the drill tubular at or above a surface of the earth during the rotating using a sensor. The method further includes estimating the downhole lateral vibrations using a processor that receives the plurality of measurements.

Abstract: A system and a method for determining stretch or compression of a drill string is disclosed. Sensors are positioned along the drill string for collecting data for determining the stretch or compression. The stretch or the compression of the drill string may be used to calculate depths at which measurements are obtained by tools associated with the drill string.

Abstract: Methods and systems may be provided for simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: Efficiency of a hydraulically driven system is evaluated by monitoring the change in ratio of output torque to input hydraulic pressure. The hydraulic pressure data is received from a hydraulic sensor. The torque data is received from a load cell receiving a force transmitted to it by a back-up wrench. Filters are applied to the data to obtain peak levels of torque and hydraulic pressure. A ratio is generated for each process associated with a rod or other elongated member based on peak torque and hydraulic pressure levels achieved during the process. The ratio is stored and compared to historical ratios to determine if the ratio has changed more than a predetermined amount over time. A similar evaluation can be achieved by comparing speed generated on the elongated member by the hydraulically driven system to the current level controlling the floss of hydraulic fluid to the hydraulically driven system.

Abstract: System, methods and devices for measuring and predicting complex borehole geometries are presented herein. A method is disclosed for determining a trajectory of a borehole that is generated by a drill string. The method includes: receiving data indicative of one or more drilling parameters between at least two survey points; averaging the received data over predetermined increments between the at least two survey points; calculating from at least the averaged data a predicted drill string response for each of the predetermined increments; determining from at least the predicted drill string response a change in inclination and azimuth for each of the predetermined increments; generating a predicted wellbore trajectory from the change in inclination and azimuth; comparing the predicted wellbore trajectory to a measured wellbore trajectory; and, if the comparison is favorable, determining a probable borehole position from the change in inclination and azimuth for each of the predetermined increments.

Abstract: Described herein is a method and system for characterizing in-ground rock types from measurement-while-drilling data in a mining environment. The method includes the steps of drilling holes at a plurality of selected locations within a region of interest; collecting measurements while drilling to obtain an array of data samples (162) indicative of rock hardness at various drilling depths in the drill hole locations; obtaining a characteristic measure (163) of the array of data samples; performing Gaussian Process regression (164) on the characteristic measure; and applying boundary detection (166) to the rock hardness output data obtained from the Gaussian process model to identify the distribution (280) of at least one cluster of rock type within the region of interest.

Abstract: A computer-assisted method for optimizing a drilling tool assembly, the method comprising defining a desired drilling plan; determining current drilling conditions; determining current drilling tool parameters of at least two drilling tool assembly components; analyzing the current drilling conditions and the current drilling tool parameters to define a base drilling condition; comparing the base drilling condition to the desired drilling plan; determining a drilling tool parameter to adjust to achieve the desired drilling plan; and adjusting at least one drilling tool parameter of at least one of the two drilling tool assembly components based on the comparing the base drilling condition to the desired drilling plan.

Abstract: 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.

Abstract: The present invention provides a computer-implemented software tool that is adapted to listen continuously to data streams from a drilling operation and to process the data to generate a situation description for a current drilling situation in a form useful for automated continuous matching with a set of past cases stored in a knowledge database. The invention implements a case-based reasoning (CBR) approach to match the current drilling situation as defined by the situation description with one or more stored past cases having a degree of similarity above a predetermined threshold level. Matching cases are displayed to the drilling engineer as symbols on a case “radar”, allowing the drilling engineer to retrieve and view the details of a past case and take appropriate action based on drilling advice provided within the past case.

Abstract: 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.

Abstract: An illustrative embodiment of a method is disclosed for assessing image quality of a down hole formation image, the method comprising collecting acquisition system data from a plurality of sensors down hole; applying a set of rules to the acquisition system data to obtain an acquisition quality indicator; and presenting the acquisition quality indicator at a surface location. A system is disclosed for performing the method.

Abstract: Downhole drilling vibration analysis uses acceleration data measured in three orthogonal axes downhole while drilling to determine whether drilling assembly's efficiency has fallen to a point where the assembly needs to be pulled. In real or near real time, a downhole tool calculates impulse in at least one direction using the measured acceleration data over an acquisition period and determines whether the calculated impulse exceeds a predetermined acceleration threshold for the acquisition period. If the impulse exceeds the threshold, the tool pulses the impulse data to the surface where the calculated impulse is correlated to efficiency of the assembly as the drillstring is used to drill in real time. Based on the correlation, operators can determine whether to pull the assembly if excessive impulse occurs continuously over a predetermined penetration depth.

Abstract: A method for constructing elastoplastic property correlations in multicomponent particulate systems. The method includes obtaining parameters from geophysical data of a sediment-hydrate system, where the parameters include shyd and pc, and where shyd is a hydrate saturation and pc is a confining pressure. The method further includes determining a Young's modulus (E) of the sediment-hydrate system using the parameters and a correlation, where the correlation is E p c = 90.58 + 78.90 ? 0.5831 + 800.4 ? s hyd 1.371 ? 1.022 , and where ?=pc/c and c is a scaling variable with dimensions of pressure. The method further includes adjusting a field operation based on the Young's modulus of the sediment-hydrate system.

Abstract: A rotating, transversely magnetized, magnet on a drill collar induces magnetization in a casing of a preexisting well. A coil rotating synchronously with the magnet produces a current at twice the frequency of rotation and having an amplitude that depends upon the distance from the magnet to the preexisting well. Alternatively, a variable magnetic field is produced in the casing using a switchable magnet.

Abstract: Methods and systems may be provided simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material. Values of bit walk rate from such simulations may be used to design and/or select drilling equipment for use in forming a directional wellbore.

Abstract: The invention is a method of constructing a three-dimensional fracture density log of a porous formation traversed by fractures and a borehole. A number N of intersections between the fractures and the borehole is measured over a section of the borehole of length L located at a depth d, from observations of the wall of this section. A conditional probability law of the three-dimensional fracture density is then estimated, knowing the number N of intersections. The value of the three-dimensional fracture density at depth d is determined by calculating the mean of this conditional probability law. Finally, the three-dimensional fracture density log is constructed by repeating the previous stages for different depths. A three-dimensional fracture density uncertainty log can also be associated by calculating quantiles of the conditional probability law.

Abstract: An apparatus for providing a downhole measurement-while-drilling (MWD) tool with diagnostic capability by including one or more printed circuit boards to the tool with firmware processors that internally record significant system diagnostic events that can be time correlated with known tool operational problems. The concept includes firmware protocol to enable transfer all of the recorded data to an external software analysis program after the MWD tool is removed from a drilling run.

Abstract: A gas analyzer system that can detect atmospheric air gasses in drilling mud is used to calculate an actual lag time in a well. The calculated lag time and a theoretical lag time may be compared to estimate a caving percentage in an open hole section of the well.

Abstract: A multi-station gravity and magnetic survey is carried out in a borehole. The data from the survey are processed to estimate the inclination and azimuth of the borehole. The drill collar relative permeability is estimated, and the estimated drill collar permeability is then used to remove the effects of induced magnetization of the drill collar on the magnetic measurements.

Abstract: Efficiency of a hydraulically driven system is evaluated by monitoring the change in ratio of output torque to input hydraulic pressure. The hydraulic pressure data is received from a hydraulic sensor. The torque data is received from a load cell receiving a force transmitted to it by a back-up wrench. Filters are applied to the data to obtain peak levels of torque and hydraulic pressure. A ratio is generated for each process associated with a rod or other elongated member based on peak torque and hydraulic pressure levels achieved during the process. The ratio is stored and compared to historical ratios to determine if the ratio has changed more than a predetermined amount over time. A similar evaluation can be achieved by comparing speed generated on the elongated member by the hydraulically driven system to the current level controlling the flow of hydraulic fluid to the hydraulically driven system.

Abstract: It is described a system and a method for for azimuth initialization of a gyroscopic and/or inertial instrument for wellbore surveying, said system comprising:—a rigid reference structure to which the gyroscopic and /or inertial instrument is rigidly connectable;—an external navigation system for providing an azimuth measurement as a function of time, and wherein the rigid reference structure provides a rigid orientation between the external navigation system and the gyroscopic and/or inertial instrument; —a processor operable to synchronize the azimuth measurement as a function of time with an orientation as a function of time of the gyroscopic and/or inertial instrument.

Abstract: An efficient and cost-effective technique is provided to perform modeling of a reservoir in a subterranean structure. A compartment model of fluid compartments in a reservoir is generated, and based on the compartment model and a geomechanical model of the subterranean structure, movement of a ground surface due to volumetric change of the compartments is calculated. Satellite measurements of the ground surface are received over time, where the received satellite measurements of the ground surface over time indicate movement of the ground surface. The movement of the ground surface indicated by the received satellite measurements is compared with the calculated movement, and based on the comparing, one or more properties of the geomechanical model are adjusted.

Abstract: Methods for imaging geological structures include injecting magnetic materials into the geological structures, placing at least one magnetic probe in a proximity to the geological structures, generating a magnetic field in the geological structures and detecting a magnetic signal. The at least one magnetic probe may be on the surface of the geological structures or reside within the geological structures. The methods also include injecting magnetic materials into the geological structures, placing at least one magnetic detector in the geological structures and measuring a resonant frequency in the at least one magnetic detector. Methods for using magnetic materials in dipole-dipole, dipole-loop and loop-loop transmitter-receiver configurations for geological structure electromagnetic imaging techniques are also disclosed.

Abstract: A method for forming a borehole image includes fitting logging sensor measurements residing in each of a plurality of azimuthal windows with corresponding mathematical fitting functions. The functions may then be evaluated at one or more corresponding azimuthal positions to obtain at least one sector value for each of the azimuthal windows. A two dimensional borehole image may be formed by repeating the procedure at multiple measured depths in the borehole.

Abstract: A method for correcting a motion related distortion in a sensor measurement comprises establishing a reference position in a borehole. A parameter of interest is measured at a plurality of toolface angles as the tool makes a revolution in the borehole. A distance to a wall of the borehole is measured associated with each parameter of interest measurement. A lateral motion of the tool is measured between each parameter of interest measurement, and a toolface angle of the tool is measured at each parameter of interest measurement. A controller comprising a processor acts according to programmed instructions to calculate a correction to the parameter of interest measurement referenced to the reference position based at least partly on the measured tool motion.

Abstract: Downhole drilling vibration analysis uses acceleration data measured in three orthogonal axes downhole while drilling to determine whether drilling assembly's efficiency has fallen to a point where the assembly needs to be pulled. In real or near real time, a downhole tool calculates impulse in at least one direction using the measured acceleration data over an acquisition period and determines whether the calculated impulse exceeds a predetermined acceleration threshold for the acquisition period. If the impulse exceeds the threshold, the tool pulses the impulse data to the surface where the calculated impulse is correlated to efficiency of the assembly as the drillstring is used to drill in real time. Based on the correlation, operators can determine whether to pull the assembly if excessive impulse occurs continuously over a predetermined penetration depth.

Abstract: A method, system and computer program product for distinguishing between a sensor fault and a process fault in a physical system and use the results obtained to update the model. A Bayesian network is designed to probabilistically relate sensor data in the physical system which includes multiple sensors. The sensor data from the sensors in the physical system is collected. A conditional probability table is derived based on the collected sensor data and the design of the Bayesian network. Upon identifying anomalous behavior in the physical system, it is determined whether a sensor fault or a process fault caused the anomalous behavior using belief values for the sensors and processes in the physical system, where the belief values indicate a level of trust regarding the status of its associated sensors and processes not being faulty.

Abstract: To characterize an earth subterranean structure using a measurement assembly including electromagnetic (EM) receivers and one or more EM sources, measured voltage data collected by EM receivers in response to transmission by one or more EM sources is received. Based on a model, predicted EM data is computed. Inversion is iteratively performed according to a function that computes a difference between the measured voltage data and a product of a term containing the predicted EM data and a term containing distortion data that accounts at least for distortion effect by an environment of the measurement assembly. The inversion is iteratively performed to solve for parameters of the model and the distortion data.

Abstract: An apparatus for estimating a property of a formation penetrated by a borehole, the apparatus having: a first electrode and a second electrode configured to couple to a characteristic impedance of a material disposed in the borehole; a third electrode configured with the first electrode to electrically couple to a characteristic impedance of the formation; a circuit element coupled to the first electrode and to the second electrode and having a characteristic impedance; a first sensing circuit coupled to the circuit element and configured to provide a first signal related to the impedance of the borehole material; and a second sensing circuit coupled to the first electrode and the third electrode and configured to provide a second signal related to the characteristic impedance of the formation; wherein the first signal and the second signal are used to estimate the property. A method is also provided.