Abstract: Disclosed herein are various embodiments of methods and systems for optimizing signals generated by microseismic sources, comprising recording microseismic data using patches of geophones, filtering the data to impart a directionality to the data, and performing a source scan to determine the times and locations of microseismic events. The subsurface is divided into a voxel grid that is further subdivided into subgrids. Using a filter designed for each patch-subgrid pair, only data arriving within a predetermined angle of incidence are input to the source scan, thus reducing noise, and enhancing the quality and accuracy of the identified microseismic events. The method is also applicable to data previously recorded with sensor grids or other arrays such as star arrays.

Abstract: A method of analyzing controlled source electromagnetic (CSEM) survey data to determine probability density functions (PDFs) for values of an electromagnetic parameter at locations in a subterranean region of interest is provided. Structural features in the subterranean strata are identified, e.g. from seismic survey data. An initial PDF for values of the electromagnetic parameter is then assigned to each feature. Models specifying values for the parameter in each structural feature are generated by sampling the PDFs. A subset of the models are deemed acceptable based on an acceptance criterion. The PDF for each feature is modified based on values for the parameter in the subset of accepted models to generate replacement PDFs for each feature. The process may be iterated a number of times to generate final PDFs for values of the electromagnetic parameter in the structural features identified in the subterranean region of interest.

Abstract: The present invention relates to a method of processing seismic image of the subsurface. The method comprises determining two surfaces in the seismic image, the two surfaces being extracted from well data from at least on well in the subsurface; determining the dip components the first surface and the second surface; determining interpolated dip components based on dip components of the two surfaces; determining an interpolated surface based on at least the interpolated dip components; determining a density value based on a number of intersections of the determined surfaces with a column comprising said current pixel; determining a geological-time image, columns of said geological-time image are computed based on the density values of pixels of a corresponding column of the seismic image; and on the color value of pixels of the corresponding column of the seismic image.

Abstract: Position, navigation and/or timing (PNT) solutions may be provided with levels of precision that have previously and conventionally been associated with carrier phase differential GPS (CDGPS) techniques that employ a fixed terrestrial reference station or with GPS PPP techniques that employ fixed terrestrial stations and corrections distribution networks of generally limited terrestrial coverage. Using techniques described herein, high-precision PNT solutions may be provided without resort to a generally proximate, terrestrial ground station having a fixed and precisely known position. Instead, techniques described herein utilize a carrier phase model and measurements from plural satellites (typically 4 or more) wherein at least one is a low earth orbiting (LEO) satellite. For an Iridium LEO solution, particular techniques are described that allow extraction of an Iridium carrier phase observables, notwithstanding TDMA gaps and random phase rotations and biases inherent in the transmitted signals.

Abstract: Assisted-GPS for a portable biometric monitoring device is provided. The portable biometric monitoring device may obtain updated ephemeris data from an associated secondary device via a short-range, low-power communication protocol. The secondary device may be a computing device such as a smartphone, tablet, or laptop. Various rules may control when the ephemeris data is updated. The ephemeris data may be used in the calculation of the global position of the portable biometric monitoring device. Additionally, the portable biometric monitoring device may communicate downloaded position fixing data to the associated secondary device. The associated secondary device may then calculate the global position from the position fixing data.

Abstract: A system, method and computer program product for seismic imaging implements a seismic modeling algorithm utilizing Forward Wave Inversion technique for revising Reverse Time Migration models used for sub-surface modeling. The technique requires large communication bandwidth and low latency to convert a parallel problem into one solved using massive domain partitioning. The partitioning of a velocity model into processing blocks allows each sub-problem to fit in a local cache, increasing locality and bandwidth and reducing latency. The RTM seismic data processing utilizes data that includes combined shot data, i.e., shot data selected from amongst a plurality of shots that are combined at like spatial points of the volume. An iterative approach is applied such that the correction term RTM generates at each iteration in the iterative approach is used for refining the model, and the updated model is used for generating a further refined RTM model.

Abstract: A method of automatically interpreting well log data indicative of physical attributes of a portion of a subterranean formation which include some portion of samples with known facies classification to be used as training data, dividing the training data into two subsets, a calibration set and a cross-validation set, using an automated supervised learning facies identification method to determine a preliminary identification of facies in the subterranean formation based on the calibration set, calculating a confusion matrix for the supervised learning facies identification method by comparing predicted and observed facies for the cross-validation set, calculating a facies transition matrix characterizing changes between contiguous facies, and using the preliminary identification, the facies transition matrix, and the confusion matrix, iteratively calculating updated facies identifications.

Abstract: One aspect of the invention is a method for building geologic/stratigraphic models of the earth for the purposes of numerical simulations of phenomena of interest, such as seismic wave propagation, or fluid flow, reservoir simulation, etc. An embodiment of the invention uses stochastic methods to create material property models that have desired statistical properties by numerically simulating deposition of geological layers. The method can create multiple material parameter models from numerical implementations of a variety of geological processes.

Abstract: Methods and systems for improving azimuth distribution in a seismic acquisition system are described. A survey acquisition system includes a plurality of streamers towed by a plurality of streamer vessels, including a first streamer vessel and a second streamer vessel and a plurality of sources towed by a plurality of source vessels. The plurality of streamer vessels and plurality of source vessels are configured relative to one another such that the plurality of source vessels are positioned at one or more predetermined inline distances behind a portion of the first streamer vessel and are also positioned at one or more predetermined inline distances in front of a portion of the second streamer vessel. The plurality of streamer vessels and plurality of source vessels are also spaced apart from one another in a cross-line direction.

Abstract: A system and method for performing stimulation operations at a wellsite having a subterranean formation with of a reservoir therein is provided. The method involves performing reservoir characterization to generate a mechanical earth model based on integrated petrophysical, geomechanical and geophysical data. The method also involves generating a stimulation plan by performing well planning, a staging design, a stimulation design and a production prediction based on the mechanical earth model. The stimulation design is optimized by repeating the well planning, staging design, stimulation design, and production prediction in a feedback loop until an optimized stimulation plan is generated.

Abstract: The description relates to a seismic imaging technology technique for modeling a subsurface structure through waveform inversion in the Laplace domain. The seismic imaging system comprises a scaled gradient calculating unit calculating a scaled gradient, a modeling parameter updating unit updating the model parameters using the scaled gradient direction, and an iteration control unit controlling the scaled gradient calculating unit and the modeling parameter updating unit to repeat processing iteratively until a stopping criteria is met.

Abstract: A method of controlling seismic data acquisition includes synchronizing a sampling rate of at least one node configured to acquire seismic data with a GPS timing signal from a first GPS seismic device; and delaying sending a start signal to one or more seismic sources, the delay being with reference to a GPS timing signal from a second GPS device.

Abstract: Described herein are implementations of various technologies for a method for in-field configuration of land survey sensors. One or more planned positions of the sensors may be received. One or more actual positions of the sensors may be determined. The actual positions may be sent to the sensors while the sensors are powered off.

Abstract: A cloud based storage system and methods for uploading and accessing 3-D data partitioned across distributed storage nodes of the system. The data cube is processed to identify discrete partitions thereof, which partitions may be organized according to the x (e.g., inline), y (e.g., crossline) and/ or z (e.g., time) aspects of the cube. The partitions are stored in unique storage nodes associated with unique keys. Sub-keys may also be used as indexes to specific data values or collections of values (e.g., traces) within a partition. Upon receiving a request, the proper partitions and values within the partitions are accessed, and the response may be passed to a renderer that converts the values into an image displayable at a client device. The request may also facilitate data or image access at a local cache, a remote cache, or the storage partitions using location, data, retrieval, and/or rendering parameters.

Abstract: Method for quantitatively assessing connectivity for well pairs at varying frequencies. A time series of measurements (12) is chosen for each of the two wells such that the particular measurements will be sensitive to subsurface connectivity if it exists (11). The two time series may then be pre-processed by resampling to time intervals commensurate with response time between the two wells (13), detrending the measurements (14), and detecting and eliminating spiking noises (15). Then the time series are transformed to the frequency domain where coherence and phase between the two series are compared for varying frequencies (16). This comparison is used to make a determination of connectivity.

Abstract: The invention is a method for extrapolating missing near-offset seismic data (101) so that the data may be used, for example, in SRME or another multiple-reflection elimination method. The invention uses the reciprocity principle (102) to relate two seismic states (acoustic or elastic) that can occur in a time-invariant, bounded domain in space. One of these states represents the physical experiment for the acquisition of the actual seismic data where near-offset traces are missing, and the other state represents a synthetic experiment with no missing near offset traces, computer-generated on a much simpler earth model. The reciprocity relationship used to relate these two states is iteratively inverted for the missing near-offset traces (103), preferably using only part of the synthetic data (102) so as to reduce inversion artifacts. The reference model acts as a constraint on the near-offset extrapolation.

Abstract: A model for predicting fracturing in shale can minimize surface disruption, protect groundwater, maximize efficiency of hydraulic fracturing, and manage fluids used in unconventional gas development. The model provides a more comprehensive understanding of the geological, geophysical, and geomechanical properties of shales and imbeds these properties in geomechanical computer simulations to predict both the reservoir performance from the fracturing, and the associated microseismic events generated by fracturing. Since the geological and geophysical properties can be estimated from surface seismic, well logs, and geologic concepts with regional context; the performance of the fracturing can be predicted and optimized. Since the microseismic events can be predicted with the model, the simulations can be verified and the model can be updated to be consistent with the observed microseismic.

Abstract: Techniques are disclosed for performing time-lapse monitor surveys with sparsely sampled monitor data sets (11). An accurate 3D representation (e.g., image) of a target area (e.g., a hydrocarbon bearing subsurface reservoir) is constructed using the sparsely sampled monitor data set (e.g., seismic data set). The sparsely sampled monitor data set may be so limited that it alone is insufficient to generate an accurate 3D representation of the target area, but accuracy is achieved through use of certain external information (14). The external information may include predetermined base survey data from a first time that is used (12) to interpolate data that is not recorded in the sparsely sampled monitor data set to derive a fully sampled monitor data set that can be processed (e.g., using conventional processing techniques) for determining an accurate representation of the target area at a second time.

Abstract: A system and method for performing stimulation operations at a wellsite having a subterranean formation with of a reservoir therein is provided. The method involves generating a plurality of quality indicators from a plurality of logs, and combining the plurality of quality indicators to form a composite quality indicator. The plurality of stress blocks may then be merged using diversion criterion. The composite quality indicator may be combined with the merged stress blocks to form a combined stress and composite quality indicator, the combined stress and composite quality indicator comprising a plurality of blocks with boundaries therebetween. The method may further comprise defining stages along the combined stress and composite quality indicator based on the diverter-assisted stage classifications; and selectively positioning perforations in select stages based on the diverter-assisted stage classifications thereon.

Abstract: A method for reconstituting a signal due to a flow distortion in a mud-pulse telemetry system, having steps of obtaining at least one parameter to be transmitted by a transmitter to a receiver through the mud-pulse telemetry system, estimating a change in a flow rate in a borehole fluid along a trajectory of the mud-pulse telemetry system undergoing a fluid distortion, estimating a Doppler rate of the signal traveling through the borehole fluid along the trajectory of the mud-pulse telemetry system, calculating a Doppler compensation value for the signal sent along the trajectory in the borehole fluid, transmitting the signal of the at least one parameter through the mud-pulse telemetry system, receiving a portion of the signal of the at least one parameter and reconstituting at least a portion of the signal using the Doppler compensation value.

Abstract: An event data processing apparatus calculates a meeting person number difference which is a difference in the number of meeting persons between a first number of meeting persons at a first time and a second number of meeting persons at a second time, determines that a continuous communication is conducted between the first time and the second time if the meeting person number difference is equal to or smaller than a meeting person number threshold value which is a predetermined threshold value, and records persons included in the first number of meeting persons and the second number of meeting persons, the first time, and the second time in association with event identifiers for identifying events in a recording module.

Abstract: A seismic survey design generation method is disclosed for generating seismic survey design data for performing a seismic survey. The survey design data purposefully violates Freznel zone constraints related to source and/or receiver bin sizes by providing exceptionally small bin sizes. In particular, the seismic survey design generation method and apparatus therefor generates seismic survey design data where the Freznel zone constraints are violated in order to obtain enhanced resolution seismic images not possible in the prior art.

Abstract: Prior information describing a distribution of values of a parameter relating to physical characteristic of a target structure is received. Acquired survey data of the target structure is received. Using a probabilistic technique, the prior information and the survey data is assimilated to produce an estimated property of the target structure.

Abstract: A system, method and computer program product for seismic imaging implements a seismic imaging algorithm utilizing Reverse Time Migration technique requiring large communication bandwidth and low latency to convert a parallel problem into one solved using massive domain partitioning. Several aspects of the imaging problem are addressed, including very regular and local communication patterns, balanced compute and communication requirements, scratch data handling and multiple-pass approaches. The partitioning of the velocity model into processing blocks allows each sub-problem to fit in a local cache, increasing locality and bandwidth and reducing latency. The RTM seismic data processing utilizes data that includes combined shot data, i.e., shot data selected from amongst a plurality of shots that are combined at like spatial points of the volume.

Abstract: A group of techniques can be used to determine if components of a seismic spread have deviated from a planned path during a coil or other curved and substantially circular acquisition pattern. In one aspect, and in general, the presently disclosed techniques include a computer-readable program storage medium for determining the deviation of spread array element from a planned curved path during a towed-array marine seismic survey. The method comprises: determining a nominal position of the spread array element at a given point in the planned curved path; determining the actual position of the spread array element; and performing an error analysis predicated on the nominal and actual positions.

Abstract: The current document is directed to computational systems and methods carried out by the computational systems for propagating a combined source-and-receiver wavefield from a first level to a next, second level with respect to depth, time, or another dimension. The methods and systems, to which the current document is directed, apply an efficient complex, combined-source-and-receiver-wavefield propagation operator to a complex combined-source-and-receiver wavefield in order to propagate the complex combined-source-and-receiver wavefield to the next level. Real source and receiver wavefields at the next, second level can then be extracted from the complex combined-source-and-receiver wavefield at the next level.

Abstract: A technique includes processing seismic data indicative of samples of at least one measured seismic signal in a processor-based machine to, in an iterative process, determine basis functions, which represent a constructed seismic signal. The technique includes in each iteration of the iterative process, selecting another basis function of the plurality of basis functions. The selecting includes based at least in part on the samples and a current version of the constructed seismic signal, determining a cost function; and interpreting the cost function based at least in part on a predicted energy distribution of the constructed seismic signal to select the basis function.

Abstract: A technique includes processing seismic data indicative of samples of at least one measured seismic signal in a processor-based machine to determine basis functions that represent a constructed seismic signal based at least in part on a matching pursuit-based technique. The technique further includes basing the determination of the basis functions at least in part on a predicted energy distribution of the constructed seismic signal.

Abstract: Methods of generating structural models of highly deviated or horizontal wells may be generated from the measurement of true stratigraphic thickness in three dimensions (TST3D). In one aspect, methods may include generating a structural model from one or more deviation surveys of a horizontal well, one or more single channel log measurements, and a three-dimensional reference surface.

Abstract: Aspects of the invention provide systems and methods for using ballast sensors to detect rock fall events in a vicinity of railway tracks or similar roadways or tracks. The ballast sensors are spaced apart from the tracks. Particular embodiments permit the use of signals from the ballast sensors to discriminate rock fall events from other types of events and to detect the hypocenter of a rock fall event.

Abstract: A method and system are described for identifying a geologic object through cross sections of a geologic data volume. The method includes obtaining a geologic data volume having a set of cross sections. Then, two or more cross sections are selected and a transformation vector is estimated between the cross sections. Based on the transformation vector, a geologic object is identified within the geologic data volume.

Abstract: Method for using a non-stationary, multi-scale domain transformation to combine multiple geophysical data sources, for example seismic data and well log data, into one coherent reservoir model. The seismic data are inverted (71) to obtain one or more geophysical properties which are converted using petrophysical relationships to a subsurface model of a reservoir property such as porosity or shale volume fraction. The well log data are used to generate a geostatistical forward model (72) of the reservoir property. Both models of the reservoir property are transformed to a joint space/scale domain, of order >1, where processing is applied (73) to merge the models into a coherent way into a single model before inverse transforming back to the space domain (74). The transform is a non-stationary multi-scale transform such as a wavelet, ridgelet, or curvelet transform. The processing may be by, for example, information theory or convex combination.

Abstract: Embodiments of a method for transforming petrophysical properties into seismic attributes are disclosed herein. Embodiments of the method utilize an AVO expression which maps lithology to P-wave reflectivity at a particular angle through their ?/? values (or equivalent elastic properties K/? and ?). Rocks with different ?/? will be projected to the different angle and reflectivity. The equation which transforms ?/? to reflection angle may be referred to as a Generalized Angle Transform Equation (GATE). Further details and advantages of various embodiments of the method are described in more herein.

Abstract: According to an embodiment, a method for analyzing microseismic events associated with hydraulic fracturing detects a new microseismic event and assigns it to a cluster of other events having similar characteristics. Cluster characteristic(s), e.g., average event(s), average source mechanisms, and/or average locations, are updated and used to characterize a future microseismic events.

Abstract: Seismic data processing using one or more non-linear stacking enabling detection of weak signals relative to noise levels. The non-linear stacking includes a double phase, a double phase-weighted, a real phasor, a squared real phasor, a phase and an N-th root stack. Microseismic signals as recorded by one or more seismic detectors and transformed by transforming the signal to enhance detection of arrivals. The transforms enable the generation of an image, or map, representative of the likelihood that there was a source of seismic energy occurring at a given point in time at a particular point in space, which may be used, for example, in monitoring operations such as hydraulic fracturing, fluid production, water flooding, steam flooding, gas flooding, and formation compaction.

Abstract: Spatial sampling is a key factor in determining acquisition parameters for seismic surveys. Acquiring the data to meet spatial sampling requirements for low, mid and high frequencies, by acquiring coarse, medium and fine acquisition grids respectively and layering these during processing, can result in reduced cost and/or higher quality surveys.

Abstract: A computer-implemented method for evaluating a geoscience data analysis question. The user inputs the question to the computer through a graphical user interface or a text command interface (11). The computer is programmed to derive a statistical measure for evaluating the question (12). One or more data elements (14) are inputted to the computer, and the derived statistical measure is applied to the data elements and computed (13).

Abstract: A system and method for regularizing irregularly sampled 5D seismic data by assigning each trace to a common midpoint bin and mapping each trace to an offset vector tile (OVT) with a calculated center azimuth; assembling an azimuth sector with all offsets of interest and a narrow range of the center azimuths from the OVTs; rotating the azimuth sector to align with an inline direction and a crossline dimension; selecting a subset of traces with a single crossline value to create an irregular 3D volume; regularizing the irregular 3D volume; and repeating as necessary to generate a regularly sampled seismic dataset. The regularization may include interpolation by an algorithm such as an anti-leakage Fourier interpolator. The regularly sampled seismic dataset may be used to characterize the subsurface by further processing such as tomography.

Abstract: A method is provided of processing data representing a physical system, the method comprising: providing (P2) input data representing differences in the physical system between a first state and a second state of the physical system; and inverting (P5) the input data, or data derived therefrom, in accordance with a parameterised model (PI) of the physical system to obtain differences in the parameters of the model between the first state and the second state, with parameters of the model representing properties of the physical system; wherein the inverting step is performed (P3 to P6) for a plurality of different perturbations (P4) of the parameterised model and/or of the data to obtain a plurality of sets of differences in the parameters of the model; and wherein a statistical analysis (P7) of the plurality of sets of differences is performed to obtain statistical characteristics of the differences in the parameters of the model.

Abstract: Disclosed herein are various embodiments of methods and systems for determining the orientation and direction of first motion of a fault or fracture by optimizing an azimuthally-dependent attribute of signals generated by microseismic sources, comprising: recording microseismic data traces using a of sensors located at a plurality of sensor positions; subdividing the subsurface volume into spatial volumes corresponding to selected time intervals and comprising a plurality of voxels; for each voxel, applying a time shift to the microseismic data traces that is substantially equal to a travel time from each voxel to the corresponding sensor position, and determining for the voxel the orientation and direction of first motion of the fault or fracture corresponding to a maximum value for the voxel of at least one azimuthally-dependent attribute of the microseismic data traces.

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: Seismic displacement demands for design of a bridge frame structure are typically determined from linear-elastic analysis (LEA), which are often incorrect, and compared to displacement capacity from a nonlinear pushover analysis. Nonlinear time-history analysis (NTHA) provides the most realistic assessment of displacement demands because it properly models the physics of the dynamic problem, wherein stiffness of the bridge varies over time. However, using NTHA to determine a bridge response from multiple earthquake motions based on the stiffness method requires excessive time. A unique approach for determining the nonlinear time-history response of a bridge frame is disclosed that is thousands of times faster than the stiffness method while providing the same results. Computational efficiency allows bridge design engineers to use NTHA for the seismic design of bridge structures by producing multiple determinations in less than one second.

Abstract: Methods, computing systems, and computer-readable media for processing seismic data. The method may include obtaining a model of a subterranean domain, and determining one or more synthetic waveforms for one or more events located in the subterranean domain, based at least partially on the model. The method may also include identifying, using a processor, one or more arrival waves in the one or more synthetic waveforms, wherein at least one of the one or more arrivals represents a mode-converted wave, and generating a processing chain for determining at least a location of an event in the subterranean domain based at least partially on the at least one mode-converted wave.

Abstract: Disclosed vertical seismic profiling (VSP) survey systems and method acquire multi-component signal data and represent the signal data in terms of a combination of parameterized compression, shear, and dispersive wavefields. Multiples of each wavefield type may be included, e.g., to separate upgoing and downgoing wavefield components. A nonlinear optimization is employed to concurrently estimate an incidence angle and a slowness value for each wavefield. For the dispersive wavefield(s), the slowness may be parameterized in terms of a phase slowness and a group slowness with respect to a central wave frequency. The parameter values may vary as a function of depth.

Abstract: A method can include receiving data sets where each of the data sets corresponds to one of a plurality of individual emitter-detector arrangements; calculating a multi-dimensional similarity metric for one of the data sets; and, based at least in part on the multi-dimensional similarity metric, assessing the one data set.

Abstract: Geologic information may be extracted from multiple offset stacks and/or angle stacks. Offset stacks and/or angle stacks may be received that represent energy that has propagated through a geologic volume of interest from energy sources to energy receivers. Attribute volumes associated with individual source-receiver offsets and/or source-receiver angles may be determined based on corresponding offset stacks and/or angle stacks. For individual offset stacks or angle stacks, corresponding sets of geologic features represented in the attribute volumes may be identified. The sets of geologic features corresponding to the different offset stacks and/or angle stacks to may be compared to determine discrepancies and/or similarities between the sets of geologic features corresponding to the different offset stacks and/or angle stacks. Stratigraphic interpretations, stratigraphic predictions, and/or other interpretations and/or predictions may be determined based on causes of the discrepancies and/or similarities.

Abstract: The present invention relates to methods and apparatuses for using head waves to greatly improve microseismic event localization accuracy, particularly in the depth dimension, by analyzing them in addition to direct path arrivals whenever they are observed. Embodiments of the invention also include techniques known as multipath analysis.

Abstract: A data set comprises data obtained by seismic imaging of a region of interest during an observation period. An intrinsic geological variability of a region is determined from the comparison of reception signals for neighbour bins as a function of a difference in signal geometry for the neighbour bins.

Abstract: Techniques for surface exploration and monitoring are presented. In representative embodiments, a system is provided that cars perform multiple types of measurements of a surface. For example a single system of survey probes and one or more survey controllers can be used to offer both seismic and electrical measurements. A survey controller can be configured to automatically poll survey probes to obtain identifiers of the probes aid determine a relative order the probes. Survey probes can be configured to: (a) collect signals associated with a surface; (b) digitize the signals to form digital data; and (c) store the digital data for later transmission to the survey controller. Relative positions of survey probes can be automatically determined using a transmitting beacon or other techniques. Survey probes can automatically disconnect from a power conduit while measuring a surface property and operate using an internal source of power when disconnected, to reduce noise.

Abstract: A method of determining a search expression describing a feature of interest in a set of data points distributed throughout a geological object is provided. Each data point contains a value for a geological attribute at that point. The search expression has a plurality of entries. The method including the steps of: (i) displaying the geological object using display codings corresponding to value subranges for the geological attribute such that all data points which have values for the geological attribute falling within a given value subrange are displayed with the same coding; (ii) selecting a plurality of data points of the feature of interest; and (iii) allocating value characters to entries of the search expression, the value characters corresponding to the value subranges for the geological attribute of the selected data points.