Abstract: A hydrocarbon exploration method for determining subsurface properties from geophysical survey data. Rock physics trends are identified and for each trend a rock physics model is determined that relates the subsurface property to geophysical properties (103). The uncertainty in the rock physics trends is also estimated (104). A geophysical forward model is selected (105), and its uncertainty is estimated (106). These quantities are used in an optimization process (107) resulting in an estimate of the subsurface property and its uncertainty.

Abstract: A system, method and computer readable medium for determining a feature in a wellbore is disclosed. A distributed temperature sensing system is disposed along the wellbore. A thermal perturbation is induced along the wellbore. A profile is determined of temperature change in response to the applied thermal perturbation using the distributed temperature sensing system. The feature of the wellbore is determined using the measured temperature profile.

Abstract: In an approach for identifying subsurface material layers, a computer processor: acquires a well log of a location to be explored, the log comprising data corresponding to multiple geophysical parameters, the data of each parameter comprising measurement values of the parameter at different depths underground; matches a reference data of each parameter corresponding to each of multiple layer transition types with the data of that parameter in the well log at depths underground, wherein each layer transition type indicates an upper material layer and a lower material layer, and the reference data is used to represent a variation trend of the parameter in a transitional zone conforming with the layer transition type; and according to the matching result, determines a layer transition type at the location to be explored and a depth of an interface between the upper material layer and the lower indicated by the layer transition type.

Abstract: The disclosure provides methods and systems for improving the interpretation of formation evaluation measurements. The methods involve using a downhole tool to measure a property of a formation at multiple depths of investigation and calculating a spatial integrated J function, a spatial integrated K function, or both from the measurements. The J function and K function are used in different applications to improve interpretation. The system includes a tool for measuring a formation property and a processor for calculating a spatial integrated J function, a spatial integrated K function from the measurements taken at different depths of investigation. The processor may also perform interpretations such as classifications, probability distributions and initialization steps for radial inversion using the J and K functions.

Abstract: A technique for processing well logs performs a nonlinear resolution enhancement of raw well logs. The nonlinear enhancement procedure uses a modified Van Cittert nonlinear enhancement technique that avoids instabilities that can arise using Van Cittert techniques. The nonlinear enhancement can provide resolution matched results at a predetermined resolution.

Abstract: The present disclosure relates to a visual interface for identifying layers within a subterranean formation. One example method includes identifying one or more sets of data associated with a subterranean formation; computing, by operation of one or more processors, a working line based on the one or more sets of data, the working line representing a numerical average of the one or more sets of data; presenting the working line and the one or more sets of data in a common plot in a visual interface; identifying one or more layer boundaries for one or more of the layers of the subterranean formation; and generating layer data based on the one or more identified layer boundaries and the working line.

Abstract: A process to create a well grid from an initial x, y grid spacing, by assigning x, y, z datapoints, from wells from a dataset of well data comprising attributes associated with the x, y, z datapoints, to closest x, y nodes in the grid, wherein the x, y, z datapoints from a plurality of the wells are iteratively spaced away from the closest x, y grid nodes until no more than one well is assigned to any single-well x, y grid node, and populating the respective single-well x, y grid nodes with the attributes associated with the assigned x, y, z datapoints to form a matrix of x, y, z grid nodes populated with the attributes to generate a 3D well log grid.

Abstract: A system for measuring a profile of a hydraulic head. A flexible liner is everted down the borehole. The profile of the transmissivity of the geologic media is obtained during (and indirectly from) the eversion of the flexible liner as it proceeds down the borehole. The liner is then retrieved by inversion from the borehole, while the pressure head in the borehole fluid below the liner is monitored and measured. From the previously obtained transmissivity profile, and the measured head within the borehole, the hydraulic head in the geologic media surrounding the borehole is determined for borehole intervals. A complete hydraulic head profile may be obtained from the collected data.

Abstract: Various resistivity logging tools, systems, and methods are disclosed. At least some tool embodiments include transmit and receive antennas that measure the electromagnetic response of the formation, at least one of which is tilted to provide a directional sensitivity. A processor converts the response (measured as a function of the tool's rotation angle) into a set of inversion parameters, which are then used to estimate the anisotropic properties of the formation. The set of inversion parameters includes at least one parameter based on an antipodal sum of the response signal, and may further include parameters based on an antipodal difference and an average of the signal response. Antipodal sum and difference values at different rotational orientations can be included in the set of inversion parameters, and they may be normalized to reduce environmental effects. Some tool embodiments collect the relevant formation measurements using parallel or perpendicular tilted antennas.

Abstract: A system and method for use in a downhole tool having distance measurement, feature detection, and primary measurement devices positioned therein are provided. In one example, the method includes recording a first plurality of features and corresponding positions in a first log using the feature detection device and the distance measurement device, respectively. A first feature of the first plurality of features is selected and the position corresponding to the first feature is identified. The feature detection device is aligned relative to the first feature based on the identified position. A first primary measurement is taken using the primary measurement device while the feature detection device is aligned relative to the first feature. The steps of recording, selecting, moving, and taking are repeated to obtain a second primary measurement while the feature detection device is aligned relative to a second feature of a second plurality of features.

Abstract: Techniques for estimating velocity ahead of a drill bit include generating seismic waves at a surface from at least two different source positions in the vicinity of a borehole, receiving seismic waves reflected from a reflector ahead of the drill bit at one or more locations in the borehole, determining travel times of the seismic waves received at the one or more locations in the borehole, and inverting the travel times to determine a velocity of a formation ahead of the drill bit. One embodiment includes transforming the velocity into pore pressure of the formation.

Abstract: A method for predicting hydrocarbon recovery in a subterranean formation may include generating pre-heating data associated with fracturing in a sample from the subterranean formation, heating the sample with RF power to cause additional fracturing in the sample, and generating post-heating data associated with additional fracturing in the sample after heating with RF power. The method may also include detecting change between the pre-heating data and post-heating data, and predicting hydrocarbon recovery from the subterranean formation based upon the detected change.

Abstract: Methods for fracture characterization of unconventional formations are provided. Synthetic seismic fracture responses can be generated based on the derived fracture parameters. The synthetic seismic fracture responses may then be used to derive optimum seismic data acquisition geometry for fracture characterization. These methods of determining the seismic data acquisition geometry are advantageous over conventional methods in that these methods are more reliable and cheaper than existing empirical methods, particularly as applied to fractured unconventional formations. Moreover, these methods allow fracture parameters to be derived from limited but common well log data. Certain embodiments additionally contemplate determining the presence of gas filled fractures. These characterizations and evaluations of unconventional formations are useful for, among other things, determining optimal producing intervals and optimal drilling locations. These methods can eliminate the use of costly image logs and core data.

Abstract: Provided are a system and method for identifying planned markers while drilling a borehole. In one example, the method includes obtaining a plan containing planned markers that each corresponds to a baseline marker from an existing well. Each of the baseline markers corresponds to a waveform from a log file obtained from the existing well and is associated with a waveform representation of the corresponding waveform. Each of the planned markers is associated with an estimated true vertical depth (TVD) value. A second log file corresponding to the borehole is obtained that contains waveforms representing formation information detected within the borehole. The second log file is scanned for a planned marker based on the estimated TVD value and the waveform representation of the baseline marker corresponding to the planned marker. At least one match may be identified and reported for the planned marker.

Abstract: An apparatus for estimating a property of a downhole fluid, the apparatus includes: a carrier configured to be conveyed through a borehole penetrating the Earth; a downhole fluid extraction device disposed at the carrier and configured to extract the downhole fluid; and a dielectric spectrometer disposed at the carrier and configured to transmit electromagnetic energy into the extracted downhole fluid at a plurality of frequencies and to measure a plurality of responses to determine a permittivity of the extracted downhole fluid as a function of frequency; wherein the permittivity is used to estimate the property.

Abstract: In some aspects, first and second boundaries are computed based on locations of microseismic events associated with a stimulation treatment of a subterranean region. Based on the first and second boundaries, an uncertainty associated with a stimulated reservoir volume (SRV) for the stimulation treatment is identified. The first and second boundaries are defined in a common spatial domain and at least a portion of the second boundary resides outside the first boundary.

Abstract: In some aspects, a closed boundary is computed based on locations of microseismic events associated with a stimulation treatment of a subterranean region. Based on the boundary, a stimulated reservoir volume (SRV) for the stimulation treatment is identified. The boundary encloses a first subset of the locations and a second, different subset of the locations reside outside the boundary.

Abstract: Disclosed is an apparatus for estimating a property of an earth formation penetrated by a borehole containing an oil-based drilling fluid. The apparatus includes an electrode disposed at a carrier and configured to inject alternating current into the formation. An electrically conductive plate is disposed between the first electrode and a borehole wall. An electrical insulator is disposed between and contacts the first electrode and the conductive plate. The apparatus is configured to prevent the drilling fluid from being disposed between the first electrode and the conductive plate. A first sensor is used to measure an electric field established between the first electrode and the conductive plate. A processor is configured to receive a measurement of the electric field to use as a floating reference signal to determine a phase difference with respect to a measured electrical quantity related to the injected electrical current in order to estimate the property.

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: A system and method of map based assessment of waterflood are provided. The method includes generating a water injection influence (WII) map by mapping one or more connectivity parameters derived from a capacitance resistance model; calculating a recovery factor (RF) and pore volumes injected (PVI) for each injector influence region in one or more influence regions defined from the connectivity parameters; determining a maximum of the recovery factor versus the pore volume injected using a curve fit extrapolation; determining a volume of injection water needed or a number of injectors needed based on recovery factor versus pore volumes injected; calculating a voidage replacement ratio (VRR) within each injector influence region; determining a target voidage replacement ratio by selecting an average voidage replacement ratio with a most recent interval of time; and determining a number of infill wells with drilling schedule to maintain the determined target voidage ratio.

Abstract: Disclosed dielectric logging tools and methods employ three or more receive horn antennas positioned between at least two transmit antennas, which can also be horn antennas. The logging tools can operate in the range between 100 MHz and 10 GHz to provide logs of formation permittivity, formation conductivity, standoff distance, and electrical properties of material in the standoff gap. Logs of water-saturated porosity and/or oil movability can be readily derived. The presence of additional receive antennas offers a significantly extended operating range, additional depths of investigation, increased measurement accuracy, and further offers compensation for tool standoff and mudcake effects. In both wireline and logging while drilling embodiments, at least some disclosed dielectric logging tools employ a set of three axially-spaced receive antennas positioned between pairs of axially-spaced transmit antennas.

Abstract: Real-time or near real-time estimates of reservoir quality properties, along with performance indicators for such estimates, can be provided through use of methods and systems for fully automating the estimation of reservoir quality properties based on geochemical data obtained at a well site.

Abstract: Methods and systems for characterizing a formation are disclosed. A tool is placed in the formation. The tool comprises a perpendicular antenna set and a parallel antenna set. The perpendicular antenna set comprises at least one transmitter antenna oriented perpendicular to at least one receiver antenna and the parallel antenna set comprises at least one transmitter antenna oriented parallel to at least one receiver antenna. Data is obtained from the tool and used to determine a compensated geosignal for each of the perpendicular antenna set and the parallel antenna set. The determined compensated geosignal is used to characterize the formation.

Abstract: Methods for computer modelling of a pressure transient behavior after shut-in and during fall-off of an injection event are provided to provide estimates of stimulated reservoir volume, formation permeability, stress contrast across the target and adjacent zones, fracture dimensions, fracture beyond the target zone, and pump pressure limits for maintaining fractures within the target zone, especially in fractured tight reservoirs.

Abstract: Techniques involve determining the frequency-dependent dielectric permittivity spectrum of a rock sample. Determining the frequency-dependent dielectric permittivity may involve defining a series of electromagnetic measurement data having at least a measurement at a frequency from which a substantially frequency-independent value of dielectric permittivity ?? can be obtained. The electromagnetic measurement data also includes measurements at different frequencies from which values for frequency-dependent dielectric permittivity ?rock (f) can be obtained. Using these measurements, the frequency-dependent spectrum of the sample may be determined.

Abstract: Cross-well electromagnetic (EM) imaging is performed using high-power pulsed magnetic field sources, time-domain signal acquisition, low-noise magnetic field sensors, spatial oversampling and super-resolution image enhancement and injected contrast fluids. The contrast fluids increase the electromagnetic character of the formation and fluids, either the magnetic permeability or the dielectric permittivity. The acquired signals are processed and inter-well images are generated mapping electromagnetic (EM) signal speed (group velocity) rather than conductivity maps. EM velocity maps with improved resolution for both native and injected fluids are provided.

Abstract: A method for managing a fracturing operation. In one implementation, the method may include positioning one or more sources and one or more receivers near a hydrocarbon reservoir; pumping a fracturing fluid into a well bore of the hydrocarbon reservoir; performing a survey with the sources and the receivers during the fracturing operation; comparing the baseline survey to the survey performed during the fracturing operation; analyzing one or more differences between the baseline survey and the survey performed during the fracturing operation; and modifying the fracturing operation based on the differences.

Abstract: Method for determining one or more optimal well trajectories and a drill center location for hydrocarbon production. A well path and drill center optimization problem (55) is solved in which one constraint is that a well trajectory must intersect a finite size target region (61) in each formation of interest, or in different parts of the same formation. The finite target size provides flexibility for the optimization problem to arrive at a more advantageous solution. Typical well path optimization constraints are also applied, such as anti-collision constraints and surface site constraints (62).

Abstract: Apparatus for making measurements in boreholes comprising a sonde having a radial array of arms provided thereon; wherein the sonde is connectable to a cartridge containing electronic circuitry specific to a predetermined measurement to be made in the borehole, each arm is connectable to a sensor pad specific to the predetermined measurement; and the sonde provides electrical connectivity between the sensor pads and the cartridge that is substantially independent of the predetermined measurement.

Abstract: A method for estimating a volume of a stimulated reservoir includes receiving a seismic signal from each microseismic event in a plurality of microseismic events in an earth formation by an array of seismic receivers. The method further includes representing each microseismic event by a plurality of markers in the three-dimensional space. A spatial distribution of the markers represents a volume of rock influenced by a microseismic event, wherein the volume and a location of each event are derived from the seismic signal. The method further includes calculating a scalar attribute for each marker in the plurality of markers, dividing the three-dimensional space into a plurality of three-dimensional grid cells, and summing the scalar attributes for all the markers in each grid cell to provide a total scalar attribute for each grid cell.

Abstract: A method for mapping remaining hydrocarbon resources in a subsurface reservoir, includes obtaining a map of seismic amplitude difference over a time period based on a survey of the subsurface reservoir, generating an expected trend dataset for the reservoir based on one or more non-water saturation effects detected over the time period by one or more wellbore surveillance techniques at one or more locations in the reservoir, correcting the map of seismic amplitude difference, at least in part, on the expected trend dataset to generate a corrected seismic amplitude map, and using the corrected seismic amplitude difference map to generate a map representative of remaining hydrocarbon resources in the reservoir. Embodiments include a system for performing the method and a medium containing computer executable software instructions for performing the method.

Abstract: The invention is a method of predicting the amount and the composition of fluids produced by mineral reactions operating within a sedimentary basin and trapped with hydrocarbons in reservoirs. Geological data characteristic of the basin are acquired and a representation of the basin by a grid is constructed. The evolution of a depth of burial (z), a temperature (T), a pore pressure (P), a volume (V) and a porosity ? at successive ages (ti) representative of the geological history of the basin is then calculated for at least one set of cells of the grid, using a basin model and the geological data. A mineralogical or chemical rock composition is determined in each cell of the set of cells from the geological data of the basin. The amount and the composition of fluids of mineral origin is determined within the set of cells using a geochemical model and an equation of state, from the parameters, the composition and a thermodynamic database.

Abstract: Downhole tools and techniques acquire information regarding nearby conductors such as pipes, well casing, and conductive formations. At least some method embodiments provide a current flow along a drill string in a borehole. The current flow disperses into the surrounding formation and causes a secondary current flow in the nearby conductor. The magnetic field from the secondary current flow can be detected using one or more azimuthally-sensitive antennas. Direction and distance estimates may be obtainable from the azimuthally-sensitive measurements, and can be used as the basis for steering the drillstring relative to the distant conductor. Possible techniques for providing current flow in the drillstring include imposing a voltage across an insulated gap or using a toroid around the drillstring to induce the current flow.

Abstract: A method for validating earth formation data for input into a geophysical model includes: determining a lithology of the earth formation; receiving measurement data for a plurality of different properties of the earth formation rock; plotting data points for a first property versus a second property in a cross-plot using the received measurement data; plotting an expected correlation between the first property and the second property on the cross-plot for rock of the determined lithology; establishing an acceptance criterion for validating the data points related to the first property and the second property with respect to the expected correlation; determining which of the plotted data points fall within the acceptance criterion to provide validated data points related to the first property and the second property; and inputting the validated data points related to the first property and the second property into the geomechanical model.

Abstract: A system includes a downhole formation fluid sampling tool. The system also includes an optical spectrometer of the downhole formation fluid sampling tool and a processor. The optical spectrometer is able to measure an optical characteristic of a formation fluid flowing through the downhole formation fluid sampling tool over a plurality of wavelengths. The optical spectrometer is designed to generate optical spectra data indicative of the optical characteristic. The processor is able to receive the optical spectra data generated by the optical spectrometer, to predict a parameter corresponding to one component of multiple components of the formation fluid based on the optical spectra data, and to calculate an uncertainty in the predicted parameter based on the optical spectra data.

Abstract: A method of subsurface imaging is disclosed, the method involving using input data relating to the geometry of a fracture in a subsurface medium, mechanical properties of the medium and in-situ stress states in the medium, to model the behavior of the fracture and obtain predicted information relating to deformation of the fracture. The predicted information is then used to constrain the interpretation of measured microseismic data caused by movement of the fracture to determine characteristics of the movement and/or failure of the fracture.

Abstract: A method for identifying fractures in a formation.

Abstract: A method for water monitoring about a deviated well is disclosed. The method includes positioning a series of electromagnetic (EM) receivers in a completed deviated wellbore, said receivers being spaced along substantially the length of the well located in a region of a reservoir to be monitored. The method also includes positioning an electromagnetic (EM) source at a first Earth surface location. Then the EM source is activated for a first survey measurement of the reservoir, and an EM field detected at each EM receiver is recorded. The EM source is moved to a second Earth surface location, and activated for a second survey measurement of the reservoir, and an EM field detected at each EM receiver is recorded. From the first and second survey measurements at each of the receivers, an inversion is performed to determine position of water about (and specifically below) the horizontal well.

Abstract: A method of estimating fluid composition in an earth formation includes: generating at least one pulsed neutron measurement by a pulsed neutron tool; estimating a pulsed neutron fluid saturation by analyzing the at least one pulsed neutron measurement via a pulsed neutron model of the earth formation, the pulsed neutron model including expected pulsed neutron measurements relative to selected fluid composition and properties; comparing the pulsed neutron fluid saturation to a reference fluid saturation estimated via a downhole tool; adjusting the pulsed neutron model to at least substantially eliminate a difference between the pulsed neutron fluid saturation and the reference fluid saturation by adjusting at least one of the selected fluid composition and the selected fluid properties; and estimating at least one of the fluid composition and the fluid properties based on the adjusted model.

Abstract: A method of estimating formation parameters in a directional drilling process by acquiring electromagnetic logging while drilling (LWD) measurements over a non-uniform forward modeling grid and inverting, using a pixel-based inversion method, the LWD measurements over a uniform inversion grid. The inversion algorithm may be applied using a sliding window scheme that allows the formation parameters to be estimated independently and in parallel across a plurality of overlapping windows which span the entirety of the inversion grid.

Abstract: A method and system for estimating reservoir pressure in a hydrocarbon reservoir from downhole pressure measurements of producing wells is disclosed. Pressure measurements are obtained from wells in the production field over time, and communicated to a server that applies the pressure measurements for a well to a model of that well. The server operates the model using the pressure measurements to determine an operating mode of the well, such as producing or shut-in. Upon detection of a change in operating mode indicative of an abrupt change in flow at the well, such as corresponding to a shut-in event, additional downhole pressure measurement data is acquired until a steady-state condition is reached. The pressure measurements are used to determine a reservoir pressure, which is transmitted to a responsible reservoir engineer or other user. Modification of the determined reservoir pressure value by the user can be received, and the stored reservoir pressure and well model are updated accordingly.

Abstract: A method for determining the frequency-dependent dielectric permittivity spectrum of a rock sample, comprising:—defining a series of electromagnetic measurement data comprising at least a first measurement at a frequency from which a substantially frequency-independent value of dielectric permittivity ??, can be obtained; and at least second and third measurements at different frequencies from which values for frequency-dependent dielectric permittivity ?rock (f) can be obtained; and—using the first, second and third measurements to determine the frequency-dependent spectrum of the sample.

Abstract: An apparatus and method for estimating a parameter of interest of an earth formation. An apparatus includes an elongated support member; a primary transmitter on the elongated support member; and a receiver toroid on the elongated support member, the receiver toroid being positioned transversely on the elongated support member and including a single coil antenna. Methods include positioning a logging tool in a borehole in the earth formation; using a transverse receiver toroid on an elongated support member on the logging tool, wherein the transverse receiver toroid includes a single coil antenna; and producing a signal responsive to an electrical signal produced by a primary transmitter.

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 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 including a first set of formation measurement points and the second depth interval including a second set of formation measurement points; establishing a plurality of trendlines of depth versus formation 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 of drilling a subterranean well from a surface location. The method comprises estimating a target formation depth, estimating a target formation dip angle and calculating a target line that creates a top and bottom of the target formation that forms a first projection window. The method further includes drilling within the first projection window, transmitting information from the subterranean well and projecting a target deviation window. The method may further comprise ceasing the drilling of the well and performing a well survey so that well survey information is generated. The method may then include estimating a formation dip angle with the well survey information and rig surface equipment monitoring data, calculating a target line that creates a revised top and bottom of the target formation that forms a second projection window, and drilling within the second projection window.

Abstract: Method for reducing artifacts in a subsurface physical properties model (120) inferred by iterative inversion (140) of geophysical data (130), wherein the artifacts are associated with some approximation (110) made during the iterative inversion. In the method, some aspect of the approximation is changed (160) as the inversion is iterated such that the artifacts do not increase by coherent addition.

Abstract: Disclosed is a method implemented by a processor for imaging a formation penetrated by a borehole. The method includes: obtaining acoustic data in a depth-time domain using an acoustic downhole tool disposed at a depth in the borehole, the acoustic downhole tool having an acoustic source and an acoustic receiver; transforming the acoustic data in the depth-time domain into a Radon domain using a Radon transform; filtering the acoustic data in the Radon domain to increase a signal of interest in the acoustic data in the Radon domain; determining a location of a point in the formation that reflected acoustic energy emitted from the acoustic source to the acoustic receiver, the location of the point being represented in the Radon domain; and inverting the location of the point represented in the Radon domain into a radius-depth domain to image the formation.

Abstract: Methods, systems, and apparatus for inducing fractures in a subterranean formation and more particularly methods and apparatus to place a first fracture with a first orientation in a formation followed by a second fracture with a second angular orientation in the formation are disclosed. The first and second fractures are initiated at about a fracturing location. The initiation of the first fracture is characterized by a first orientation line. The first fracture temporarily alters a stress field in the subterranean formation. The initiation of the second fracture is characterized by a second orientation line. The first orientation line and the second orientation line have an angular disposition to each other.

Abstract: A method for surveying, may include receiving, by a processor, first survey data from a first source, the first source comprising a first signal generated by a subsurface earth formation in response to a passive-source electromagnetic signal, wherein the electromagnetic signal is generated by an electroseismic or seismoelectric conversion of the passive-source electromagnetic signal. The method may also include receiving, by the processor, second survey data from a second source and processing the first survey data and the second survey data to determine one or more properties of a subsurface earth formation.

Abstract: A system and method are provided for automatically correlating geologic tops. The system receives well logs from different well bores and one or more user seed picks identifying a well top to be correlated. Each of the seed picks is added to a priority queue ordered by each pick's confidence. User selected picks are assigned the highest level of confidence. The system performs correlation by selecting a window of well log data about a user's manual pick, selected from the top of the priority queue, and then finding the best optimal match with a corresponding window in a neighboring wellbore. That new pick is then estimated in the target well using a correlation function. A quality value and a confidence value may then be calculated for each pick using some correlation function, for example dynamic time warping, and added to the priority queue according to the confidence value.