Abstract: A logging-while-drilling system for efficiently providing a reliable measurement of various petrophysical properties of subsurface earth formations.

Abstract: A series of scans is generated for a subsurface and a derivative image is created using the series of subsurface images. One or more tests are performed on the derivative image, and a subsurface object is detected based on the one or more tests. A sensor is configured to generate a series of scans for a subsurface and a processor is coupled to the sensor. The processor is configured to execute stored program instructions that cause the processor to generate a series of images of the subsurface using the series of scans, create a derivative image using the series of subsurface images, perform one or more tests on the derivative image, and detect a subsurface object based on the one or more tests.

Abstract: This invention is directed to a downhole method and apparatus for simultaneously determining the horizontal resistivity, vertical resistivity, and relative dip angle for anisotropic earth formations. The present invention accomplishes this objective by using an antenna configuration in which a transmitter antenna and a receiver antenna are oriented in non-parallel planes such that the vertical resistivity and the relative dip angle are decoupled. Preferably, either the transmitter or the receiver is mounted in a conventional orientation in a first plane that is normal to the tool axis, and the other antenna is mounted in a second plane that is not parallel to the first plane. Although this invention is primarily intended for MWD or LWD applications, this invention is also applicable to wireline and possibly other applications.

Abstract: An orientation vector, referred to hereinafter as the “geosteering vector,” is directed to the more conductive formation area within the DOI of the tool and away from the more resistive formation areas. Accordingly, drilling in a direction opposite the geosteering vector leads to more resistive formation. Also, the disclosed geosteering vectors obtained from the real and imaginary components will not align with each other for non-planar formations and therefore the misalignment of the geosteering obtained from real and imaginary components is indicative of a non-planar formation. A superposition method is disclosed which can be used to calculate electromagnetic (EM) couplings in a non-planar geometry formation (as well as in a planar geometry formation) in real time, without requiring two or three dimensional modeling calculations.

Abstract: A method for analyzing formation data includes decomposing the formation data into simple components that can be used to reconstruct the formation data, wherein the decomposing is performed at a first location and includes a process to minimize an overlap between the simple components; and transmitting parameters representing the simple components to a second location for reconstructing the formation data. A system for analyzing formation data that includes a processor and a memory that stores a program having instructions for decomposing the formation data into simple components that can be used to reconstruct the formation data, wherein the decomposing is performed at a first location and includes a process to minimize an overlap between the simple components; and transmitting parameters representing the simple components to a second location for reconstructing the formation data.

Abstract: 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 measurements by which the effects of steel casing are reduced.

Abstract: A method for determining permeability of a subsurface formation includes measuring a parameter related to fluid content of the formation at a first time from within a wellbore penetrating the formation. A rate of entry of fluid from the wellbore into the formation is determined from the measurement of the parameter made at the first time. The permeability is determined from the rate of entry.

Abstract: A method for analyzing a formation, that includes plotting resistivity data points on a resistivity graph to obtain plotted resistivity data points, and selecting a first shale point on the resistivity graph based on the plotted resistivity data points. The first shale point represents a resistivity anisotropy of shale in the formation. The method further includes generating, for each of a plurality of shale fraction values, a first shale fraction curve on the resistivity graph based on the shale fraction value and the first shale point, and generating, for each of a plurality of sand resistivity values, a first sand resistivity curve on the resistivity graph based on the sand resistivity value and the first shale point. A hydrocarbon yielding region in the formation is identified based on the first sand resistivity curves and the first shale fraction curves.

Abstract: Methods and apparatus to process measurements associated with drilling operations are described. An example method of modifying processing results during a subterranean formation drilling operation includes identifying a plurality of parameters and processing measurements associated with the subterranean formation obtained while drilling and the plurality of parameters to generate first results. Additionally, the example method includes processing measurements associated with the subterranean formation obtained while drilling is temporarily suspended and the plurality of parameters to generate second results and comparing the first and second results. Further, the example method includes, in response to the comparison of the first and second results, modifying the first results based on the second results to improve a quality of the first results.

Abstract: A wellbore tool for optimizing magnetic signals is provided. The wellbore tool has a tool body and an electric current driving device with an insulated gap on the downhole tool body. The electric current driving device generates electric current across the gap. The wellbore tool has a a magnetometer capable of measuring a magnetic field.

Abstract: A method for mapping sub-surface resistivity contrasts comprising making multi-channel transient electromagnetic (MTEM) measurements using at least one electric source with grounded input current electrodes or one magnetic source with current in a wire loop or multi loop and at least one electric field or magnetic field receiver, measuring the resultant earth response simultaneously at each receiver using a known recording system, measuring the system response by measuring directly the current in the wire at the source using effectively the same recording system, using the measured system response to recover the impulse response of the earth from each measured earth response, and creating from such impulse responses a sub-surface representation of resistivity contrasts.

Abstract: This invention is directed to a downhole method and apparatus for simultaneously determining the horizontal resistivity, vertical resistivity, and relative dip angle for anisotropic earth formations. The present invention accomplishes this objective by using an antenna configuration in which a transmitter antenna and a receiver antenna are oriented in non-parallel planes such that the vertical resistivity and the relative dip angle are decoupled. Preferably, either the transmitter or the receiver is mounted in a conventional orientation in a first plane that is normal to the tool axis, and the other antenna is mounted in a second plane that is not parallel to the first plane. Although this invention is primarily intended for MWD or LWD applications, this invention is also applicable to wireline and possibly other applications.

Abstract: Method for assessing hydrocarbon source rock potential of a subsurface region without well log information. The method uses surface electromagnetic (121) and seismic (122) survey data to obtain vertical profiles of resistivity and velocity (123), which are then analyzed in the same way as well log data are analyzed by the well known DeltaLogR method (124).

Abstract: A method of determining water saturations from a deep-reading resistivity measurement in a reservoir is provided including the step of estimating, through for example a reservoir simulation process, a spatial distribution of a parameter related to the water conductivity at locations beyond the immediate vicinity of wells penetrating the reservoir and combining the spatial distribution of a parameter related to the water conductivity with a spatial distribution of resistivity as obtained from the deep-reading resistivity measurement to derive a spatial distribution of water saturations at said locations beyond the immediate vicinity of wells, wherein estimation step may be iterative to minimize a mismatch between simulation and measurement.

Abstract: A technique provides a methodology for improving surveys of subterranean regions. The methodology comprises estimating macro anisotropy and an intrinsic or micro anisotropy of an overburden. A surface electromagnetic survey is conducted, and the data from the survey is inverted based on or including information gained from estimating the macro anisotropy and/or intrinsic anisotropy. A processor system can be used to conduct the inversion with the adjustments for anisotropy to improve the information provided by the survey.

Abstract: A method is disclosed, which is practiced by a reservoir simulator, for simulating a reservoir and generating a set of simulation results, the simulation results including a framework, the framework further including a plurality of grid cells, comprising: generating one or more static and dynamic regions within the grid cells of the framework of the simulation results, the static and dynamic regions each having region values, wherein the region values of the static regions cannot be allowed to change dynamically, and wherein the region values of the dynamic regions can be allowed to change dynamically.

Abstract: In electrical resistivity tomography and electrical impedance tomography, interference effects of the metal well casing can be reduced by disposing measurement electrodes in the form of conductive bands around a region of primary insulation on the well casing. Secondary insulation can be provided longitudinally adjacent the primary insulation to further reduce the interference effects. Parameters of the primary and secondary insulation may be determined using finite element methods. The conductive band electrode can connect to a wire of a multi-strand cable using a novel takeout arrangement. Novel measurement methods are also described.

Abstract: A phase error in measurements made by a resistivity logging tool is estimated by positioning the tool above a conducting surface. Deviation of the measured phase difference between the transmitter and the receiver from 90° gives the phase error in the electronics. 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.

Abstract: Joint processing of seismic and controlled source electromagnetic (CSEM) surface data is performed by using a common rock physics model which relates reservoir properties (such as porosity, lithology, saturation, and shaliness) to surface seismic AVO (or AVA) data. This allows one to determine how perturbations in the reservoir properties affect surface data. This can be carried out by systematically changing the reservoir properties and examining the effect on the synthetic data. This allows the hydrocarbon type of a reservoir to be established, e.g. oil or gas, as well as the saturation level of the hydrocarbon in the reservoir, which is useful for determining whether the reservoir has a non-commercial, low hydrocarbon saturation or a commercial, high hydrocarbon saturation.

Abstract: A method for imaging a geologic deposit using data collected from a borehole includes: selecting an instrument for performing electromagnetic (EM) measurements, the instrument including at least one transmitter and at least one orthogonally oriented receiver; obtaining EM measurement data from the borehole with the instrument; transforming the EM measurement data to acoustic data; and estimating at least one of a direction and a distance from the instrument to the deposit from the data. A computer program product and a system are provided.

Abstract: Methods and systems are provided for evaluating petrophysical properties of subterranean formations and comprehensively evaluating hydrate presence through a combination of computer-implemented log modeling and analysis. Certain embodiments comprise the steps of running a number of logging tools in a wellbore to obtain a variety of wellbore data and logs, and evaluating and modeling the log data to ascertain various petrophysical properties. Examples of suitable logging techniques that may be used in combination with the present invention include, but are not limited to, sonic logs, electrical resistivity logs, gamma ray logs, neutron porosity logs, density logs, NRM logs, or any combination or subset thereof.

Abstract: A method and instrument provide a very detailed symmetric resistivity image of a formation. A first asymmetric resistivity image is collected from a first arrangement of electrodes, which form an asymmetric sensor. A second asymmetric resistivity image is collected from a second arrangement of electrodes, which form an asymmetric sensor. The first image and the second image overlap each other. The images are assembled about a selected reference point and then processed to provide the very detailed symmetric resistivity image.

Abstract: Sequential measurements are made using a two terminal resistivity imaging device wherein the measure electrodes are activated sequentially with the remaining electrodes in a floating mode. This eliminates the hardware requirements for focusing electrodes, prevents galvanic leakage between proximal electrodes and the effects of mutual coupling between circuits including proximal electrodes.

Abstract: The present disclosure relates to a method to determine the capture cross-section of a subsurface formation at a desired depth in the formation. A database of Sigma values for known lithologies, porosities, and salinities is provided, and multiple Sigma measurements are obtained from a downhole logging tool. Within the database, Sigma values are interpolated to determine the respective depths of investigation of the multiple Sigma measurements. A monotonic function is fitted to the multiple Sigma measurements at the determined depths of investigation, and the capture cross-section of the subsurface formation at any desired depth in the formation is determined using the fitted function. Similarly, a system to determine the capture cross-section of a subsurface formation at a desired depth in the formation and/or a depth of invasion of drilling fluids is also disclosed.

Abstract: A technique includes using a first sensor to perform a first electromagnetic field measurement to obtain first data, which is indicative of the presence of a resistive body. The first data is relatively sensitive to an effect that is caused by an air layer boundary. The technique includes using a second sensor to perform a second electromagnetic field measurement to obtain second data, which is indicative of the presence of the resistive body. The second data is relatively sensitive to the effect, and the first and second sensors are either both magnetic field sensors or both electric field sensors. The technique includes combining the first and second data to generate third data, which is relatively insensitive to the effect and is indicative of the presence of the resistive body.

Abstract: A method of determining the dielectric constant of a formation, comprising acquiring phase-related and amplitude-related measurements for electromagnetic signals propagating though the formation from a transmitter to a receiver; deriving a complex-valued quantity comprising terms relating to the phase shift and attenuation of the signals; defining a one-component complex-valued relationship relating the phase shift, attenuation and complex dielectric constant; and using the derived complex-valued quantity in the defined relationship to obtain a calculated value of the complex dielectric constant. An apparatus for determining the dielectric constant of a formation, comprises a transmitter for transmitting electromagnetic signals into the formation; a receiver for receiving the electromagnetic signals that have propagated from the transmitter through the formation; and means for determining the dielectric constant of the formation in accordance with a method according to the first aspect of the invention.

Abstract: A method for processing well logging data includes method dividing the well logging data into a number of constant dimensional effect segments, where each constant dimensional effect segment defines an interval having a similar dimensional effect on the log response. The well logging data is taken from a highly deviated well, which may include portions deviated at greater than 90-degrees. The method further includes dividing the constant dimensional effect segments into a number of constant property intervals, each constant dimensional effect segment including at least one corresponding constant property interval, and each constant property interval defining a wellbore distance over which a formation property is substantially constant that results in a log response having a low variance. The method further includes providing the constant property intervals to an output device.

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: A compensated resistivity logging while drilling tool having axially asymmetrically spaced transmitters is configured to provide compensated resistivity measurements. In one exemplary embodiment, the tool includes first and second compensating transmitters, preferably deployed axially symmetrically between first and second spaced receivers. The tool further includes a plurality of transmitters deployed axially asymmetrically with respect to the receivers, e.g., on one axial side of the receivers. The compensating transmitters are configured to acquire a borehole compensation that may be subtracted from conventional phase and attenuation measurements.

Abstract: An apparatus for determining the concentration of a conductive fluid present in a fluid filled bore hole is described. Such apparatus are known as water hold-up meters and are frequently used in oil, gas and water filled bore holes. In bore hole applications, data bandwidth between a down hole device and the surface can be limited, while determining water hold-up based on down hole measurements can be data intensive. A technique is proposed for calculating the water hold up that requires less data to be transmitted between the down hole device and the surface.

Abstract: 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.

Abstract: Method for removing air wave noise from shallow water controlled source electromagnetic survey data, using only the measured data and conductivity values for sea water (140) and air. The method is a calculation performed numerically on CSEM data and resulting in an estimate of those data that would have been acquired had the water layer extended infinitely upward from the seafloor. No properties of the sub-sea sediments are used. Synthetic electromagnetic field data are generated for (a) an all water model (141) and (b) an air-water model (146-147) of the survey region. These simulated results are then used to calculate (148-150) electromagnetic field values corresponding to a water-sediment model with water replacing the air half space, which represent measured data adjusted to remove air wave noise.

Abstract: An artificial neural network, ANN, and method of training the ANN for inversion of logging tool signals into well logs of formation parameters is disclosed. Properly selected synthetic models of earth formations are used to train the ANN. The models include Oklahoma and chirp type of formations. In each model parameter contrasts of from 10 to 1 to about 100 to 1 are included. Models including maximum and minimum parameter values spanning the operating range of the selected logging tool are included. Parameter contrasts at interfaces are limited to realistic values found in earth formations. The selected models are used to generate synthetic tool signals, which are then used as inputs to the ANN for training. When the ANN coefficients are properly adjusted to produce an output matching the original models, the ANN can be used for inversion of any real signals from the selected logging tool.

Abstract: The system and method provided modify a conventional seafloor long-wire electromagnetic (LEM) receiver by increasing the number of discrete antennae placed on the long wire. Two dipoles of electric field data are positioned exactly adjacent to each other, providing input to the same data logger system located within a seafloor survey unit to which the long wire is connected. Highly precise electric field gradients can be obtained by taking the difference of the measurements of the two electrodes, both for amplitude and phase. Any common-mode source of noise, such as magnetotelluric signals and receiver instrument noise will be rejected when the signals from the two electrodes are differenced. An acoustic navigation system utilizes a plurality of transponders to permit triangulation for accurate source-receiver ranging.

Abstract: Methods and related systems are described for analyzing electromagnetic survey data. Electromagnetic survey data of a subterranean formation is obtained using at least a downhole transceiver deployed in a borehole and a transceiver positioned on the surface or in another borehole. The electromagnetic survey data includes an incident wave component and a scattered wave component. The incident and scattered components are correlated so as to generate an image of the subterranean formation indicating spatial locations of one or more features, for example, electrical properties such as resistivity variations, in the formation. The image is based at least in part on one or more interference patterns of the incident and scattered wave components. The correlation preferably includes generating a simulation of the incident wave component propagated into the formation, and convolving the simulated propagated incident wave component with the scattered wave component.

Abstract: Systems and methods in which data compression techniques are utilized to fill a predetermined channel capacity are shown. According to one configuration, event data points within test data are selected for communication via the data communication channel and a data decimator is utilized to identify other data points within the test data to fill or substantially fill the predetermined channel capacity. The foregoing data decimator may employ one or more variables for selecting data for communication, wherein one or more of the variables are preferably adjusted in decimator iterations to select an optimum or otherwise desirable subset of data for communication. Data decimators may additionally or alternatively implement a suitable “growth” function to select the particular data for communication and/or the amount of data communicated.

Abstract: The method for correcting the phase of measured electric signals or magnetic signals of field data from a controlled source electromagnetic survey (CSES) by comparing the measured field data corresponding to a selected frequency to the simulated data for various signal source receiver offsets (71) and correcting the phases of the actual data based on the phase difference for a selected range of small signal offsets (76) based on a go-electric model.

Abstract: The invention is a method for inverting reservoir bi-axial anisotropy and identifying complicated fracture/cross-bedding system (104) by using tri-axial induction logs and wellbore survey/image log data. An inversion method is disclosed that uses all nine components that can be measured by tri-axial induction tools (101), plus borehole azimuth and deviation data, to solve for the tri-axial induction response in an arbitrary anisotropic formation due to the non-orthogonal bedding plane and fracture plane (or cross bedding plane). A mathematical formula is provided relating the conductivity tensor in the tool's reference frame to the conductivity tensor in a reference plane associated with the fracture/cross bedding planes (102). This equation is inverted (103) to yield the conductivity tensor components in the fracture/cross bedding coordinate system, along with dip and azimuth angles for both the fracture/cross bedding planes and the tool.

Abstract: A method for determining resistivity anisotropy of subsurface rock formations from measurements of response to a transient electromagnetic field imparted into the subsurface and measured at a plurality of distances from a position of the imparting includes that for each offset, a step response of the formations is determined at a time from the imparting selected such that the step response is related substantially only to horizontal resistivity and at a time from the imparting selected such that the step response is related substantially only to mean resistivity. The horizontal resistivity step response and the mean resistivity step response are used to determine the resistivity anisotropy.

Abstract: A wireline telemetry system and method of transmitting data on multiple carrier frequencies. The system and method adjust power level and number of bits-per-carrier to optimally or near-optimally utilize the capacity of the wireline cable. Due to the nature of wireline telemetry the overall power level is restricted only by the output capability of the downhole telemetry cartridge and the input power restrictions of the uphole telemetry unit receiver. The optimal power level is determined during a training sequence and is a function of such factors as cable length, cable material, cable temperature and cable geometry. The uplink and downlink transmission are executed using different modulation techniques.

Abstract: An exemplary embodiment of the present invention provides a method for interpolating seismic data. The method includes collecting seismic data of two or more types over a field (401), determining an approximation to one of the types of the seismic data (402), and performing a wave-field transformation on the approximation to form a transformed approximation (405), wherein the transformed approximation corresponds to another of the collected types of seismic data. The method may also include setting the transformed approximation to match the measured seismic data of the corresponding types at matching locations (408), performing a wave-field transformation on the transformed approximation to form an output approximation (412), and using the output approximation to obtain a data representation of a geological layer (416).

Abstract: Measurements made by a multi-component induction logging tool are corrected for tool eccentricity in a deviated borehole. The eccentricity angle is determined from single frequency skin-effect corrected data and is then used to correct multifrequency data. Multifrequency focusing is then applied to the corrected multifrequency data. An inversion is then used to recover formation resistivity and relative dip and azimuth of the borehole.

Abstract: A method of measuring a parameter characteristic of a rock formation is provided, the method including the steps of obtaining crosswell electromagnetic signals between two wells and using an inversion of said signals to investigate or delineate the presence of a resistivity anomaly, such as brine in a low resistivity background, wherein the resistivity anomaly is assumed to be distributed as one or more bodies characterized by a limited number of geometrical parameters and the inversion is used to determine said geometrical parameters. The method can also be applied to determine the trajectory of an in-fill well to be drilled.

Abstract: A method for estimating a fracture aperture in a formation penetrated by a well includes obtaining at least one of a vertical resistivity (Rv) and a horizontal resistivity (Rh) of the formation; obtaining a mud resistivity (Rmud) or a matrix resistivity (Rmatrix); and estimating the fracture aperture. The estimating of the fracture aperture may be performed by solving the following two equations: Rv=Vhf·Rm+(1?Vhf)·Rmatrix and 1/Rh=Vhf·1/Rmud+(1?Vhf)·1/Rmatrix, wherein Vhf is the fracture aperture.

Abstract: A multicomponent induction logging tool is used on a MWD bottomhole assembly. Multifrequency focusing that accounts for the finite, nonzero, conductivity of the mandrel is applied. Using separation of modes, the principal components and relative dip angles in an earth formation are determined. The results are used for reservoir navigation in an earth formation.

Abstract: Methods and related systems are described relating to an inversion approach for interpreting the geophysical electromagnetic data. The inversion can be constrained by using a multiphase fluid flow simulator (incorporating pressure data if available) which simulates the fluid flow process and calculates the spatial distribution of the water saturation and the salt concentration, which are in turn transformed into the formation conductivity using a resistivity-saturation formula. In this way, the inverted invasion profile is consistent with the fluid flow physics and moreover accounts for gravity segregation effects. Jointly with the pressure data, the inversion estimates a parametric one-dimensional distribution of permeability and porosity. The fluid flow volume is directly inverted from the fluid-flow-constrained inversion of the electromagnetic data.

Abstract: An apparatus having transmitter and receiver antennas is provided for measuring conductivity of an earth formation surrounding a borehole. The apparatus utilizes an initial model to invert induction measurements of the earth formation to provide a conductivity model that includes a plurality of coaxial cylinders.

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: Resistivity measurements are made with a propagation resistivity tool in a plurality of different modes wherein the antennas may be used as both transmitters or receivers. 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.

Abstract: Multi-component induction measurements are made using a resistivity logging tool in an anistropic earth formation. A subset of the multi-component measurements are inverted to first determine horizontal resistivities. Using the determined horizontal resistivities and another subset of the multi-component measurements, the vertical resistivities are obtained. Results of using the in-phase signals are comparable to those obtained using multifrequency focusing of quadrature signals.