Abstract: Methods and apparatus are provided for generating velocity models for pre-stack depth migration (“PSDM”). Seismic, gravity and electromagnetic joint inversion input data are generated based on observed seismic, gravity and electromagnetic data (e.g., magnetotelluric and/or controlled source electromagnetic), and velocity, density and resistivity models. A joint inversion is performed to produce a multiparametric model that is a function of velocity, density and resistivity parameter distributions. The separate parameter distributions are extracted from the multiparametric model, and the extracted velocity model is used to perform a PSDM. A migration velocity analysis is performed on PSDM output to generate seismic image residuals. If the seismic image residuals meet predetermined quality objectives, the extracted velocity model is output as the final velocity model for PSDM.

Abstract: Shallow drilling hazards (44), such as karsts, caves, voids and unconsolidated discontinuities, that can pose significant risks to exploration and development well drilling operations are detected employing seismic refraction data on which a series of attribute analyses are performed, the resulting data being further processed to provide a three-dimensional visualization. Refracted wave raypaths (40, 46, 48) are highly distorted by encountering a karst feature with the occurrence of backscattering absorption. The resultant energy recorded at the surface receivers (52) is significantly reduced as compared to refracted waves recorded by other receivers (50) where no karsting is present. Multiple refractors are subjected to a relatively simple and rapid processing using commercially available software to track these differences and to map them in the near surface to improve the siting of wells and to alert drilling engineers and crews to the possibility of encountering the hazard.

Abstract: The invention relates to a method for fracture plane reconstruction in a three-dimensional set (20) of values, comprising the steps of providing a computer with the three-dimensional set, display by the computer of a succession of plane sections (10) of the three-dimensional set, selection by the user of points of the fracture plane over some of these sections during their display; and reconstruction by the computer of the fracture plane from the selected points.

Abstract: A method is disclosed for more accurately determining the relative bearing angle of a directional receiver in a borehole using an existing three-dimensional (3D) geological model, one or more seismic sources and a three component (3C) directional receiver. A disclosed method includes: receiving direct compressional arrivals generated by multiple source events at the directional receiver disposed in the borehole; rotating the seismic data into the true earth frame using an estimated relative bearing angle; measuring a polarization vector of the rotated seismic data; estimating an incident ray vector of the direct compressional arrivals at the directional receiver using ray-tracing through the 3D model; calculating the weighted sum of an angular difference between the polarization vector and the incident ray vector; and adjusting the estimated relative bearing angle until the angular difference between the polarization and incident ray vectors is minimized.

Abstract: A method for providing a velocity profile for a subsurface region that includes the reflective interfaces, the method comprising the steps of: providing a set of data comprising signals transmitted by a transmitter and collected at a receiver, wherein the data include a primary signal that has been reflected off of one of the reflective interfaces and a multiply-reflected signal that has been reflected off of at least two of the reflective interfaces, providing a velocity model for the subsurface region, using the velocity model and the primary signal to construct a first image of the subsurface region, using the velocity model and the multiply-reflected signal to construct a second image of the subsurface region, determining a measure of match between the first and second images, adjusting the velocity model based on this measure, and repeating the steps until the measure of match attains a desired level.

Abstract: Integrated computing systems and methods for applying sub-surface material location and composition information to engineering plans for designing, highways and other roadways, are provided. Utilizing the described systems and methods, surfaces, highways, may be more efficiently designed in a timely fashion, requiring less format conversion for inputs and outputs to be compatible throughout the design process. Additionally, adjustments for changes in alignments for the desired surfaces are more easily taken into account than in conventional design systems, permitting quicker design corrections and more accurate results.

Abstract: Method for determining an expected value for a proposed reconnaissance electromagnetic (or any other type of geophysical) survey using a user-controlled source. The method requires only available geologic and economic information about the survey region. A series of calibration surveys are simulated with an assortment of resistive targets consistent with the known information. The calibration surveys are used to train pattern recognition software to assess the economic potential from anomalous resistivity maps. The calibrated classifier is then used on further simulated surveys of the area to generate probabilities that can be used in Value of Information theory to predict an expected value of a survey of the same design as the simulated surveys. The calibrated classifier technique can also be used to interpret actual CSEM survey results for economic potential.

Abstract: There is provided herein a system and method for the imaging and monitoring of hydrocarbon reservoirs and other subsurface features preferably using seabed or surface sensors in conjunction with one or more downhole sensors. In one preferred embodiment, recordings will be simultaneously made using both seabed and downhole receivers. The energy source might be either a controlled seismic source or ambient noise. In one embodiment, the data will be used to compute a virtual VSP, checkshot, or similar survey by cross correlating a trace recorded at the surface with a trace recorded at depth. In another embodiment, the surface and well sensors will be permanently emplaced and repeated recordings over time will be used to form a time-varying (4-D) image of the subsurface.

Abstract: Systems and methods perform correction of velocity cubes for seismic depth modeling. An example system receives a velocity model defined in the time domain for seismic modeling of a subsurface earth volume and receives well depth data associated with the subsurface earth volume. The system updates an average velocity cube associated with the velocity model to correct depth-converted time horizons to accord with known well markers, thereby increasing the accuracy and correctness of the velocity model.

Abstract: A method of determining geological information related to a subsurface volume. In one embodiment, the method comprises obtaining a seismic information related to a subsurface volume; determining a horizon volume that automatically maps the seismic information into a flattened volume, wherein one axis of the flattened volume corresponds to chronostratigraphic time, and wherein horizons represented by the seismic information are automatically accounted for in the horizon volume, and are shifted by the horizon volume into the flattened volume to be substantially planar and substantially perpendicular to the axis of the flattened volume that corresponds to chronostratigraphic time; determining a derivative of the horizon volume with respect to chronostratigraphic time; and determining geological information related to the subsurface volume based on the derivative of the horizon volume with respect to chronostratigraphic time.

Abstract: A method of determining a horizon volume. In one embodiment, the horizon volume is determined from obtained seismic information, and maps the obtained seismic information onto a flattened volume such that in the flattened volume, horizons represented in the obtained seismic information are shifted to be substantially coplanar with a surface defined by the horizon volume as an estimate of a single chronostratigraphic time such that the parameters of the flattened volume include (i) a two-dimensional position in a surface plane, and (ii) a metric related to chronostratigraphic time.

Abstract: The present invention comprises a method of choosing a cell structure for seismic gathers dictating a grid of azimuth-offset bins that can be of various shapes and sizes. Processes that use offset-azimuth information are optimized to operate on these cells of azimuth-offset bins and invert for seismic properties. The method provides for acquisition of 3D seismic data, selecting a seismic gather bin for sorting the data, selecting at least one cell structure for the gather that may or may not be space filling, and sorting the data in to the cell structure of the gather bin. The cell structures may be any shape including hexagonal, and may be of variable sizes and may overlap.

Abstract: A computer-implemented method, system, computer-readable medium, and apparatus for identifying a boundary of a cluster in a bitmap, the bitmap having at least one initially set bit, for applying an expansion shape to each of the initially set bits in the bitmap and identifying vertex bits on the boundary of the cluster formed by at least one expansion shape.

Abstract: A technique for processing acoustic waveforms includes: (a) transforming at least a portion of the acoustic waveforms to produce frequency-domain signals; (b) obtaining a model dispersion curve based on a borehole-formation model having a set of borehole-formation parameters; (c) adjusting phases of the frequency-domain signals according to the model dispersion curve to produce back-propagated signals; (d) computing coherence of the back-propagated signals; (e) repeating steps (b)-(d) by varying values of the set of borehole-formation parameters until the coherence reaches a selected criterion; and (f) outputting at least a portion of the set of borehole-formation parameters.

Abstract: Method for aligning converted wave seismic reflection data (PS data) with conventional PP seismic reflection data so that both data types may be used to more accurately image the subsurface for hydrocarbon exploration or field development. Amplitude vs. angle (AVA) or amplitude vs. offset (AVO) attributes of PP and PS seismic data are identified and defined, which attributes are theoretically expected to be in phase and optimize seismic resolution in the data. In one embodiment of the invention, such attributes are calculated (310), then the same horizons are identified in a series of PP attributes and in a series of PS attributes, then the second series is aligned with the first at the horizon locations (316, 320), then a time transfer function is generated and applied to the PS mode data (322), and the aligned joint-mode data are inverted (326) using, for example, AVA attributes.

Abstract: A method of TI formation evaluation is disclosed. The method comprises receiving a plurality of borehole measurements; deriving a correlation between a first TI stiffness parameter and other TI stiffness parameters where the first and other TI stiffness parameters representing mechanical behavior of the TI formation; and computing the first and other TI stiffness parameters based on the borehole measurements and the derived correlation. The method further comprises evaluating TI formation elastic properties based on the computed first and other TI stiffness parameters. The method further comprises assuming that the shear modulus parallel to TI symmetric axis can be approximated from other moduli.

Abstract: A method for determining structure in the Earth's subsurface includes generating an initial model of the structure. The initial model includes at least one layer boundary. A wellbore is drilled along a selected trajectory through the Earth's subsurface in a volume represented by the initial model. At least one formation parameter is measured azimuthally along the wellbore. A distance is determined from the wellbore at selected positions therealong to the at least one layer boundary using the azimuthal formation parameter measurements. The initial model is adjusted using the determined distances. In one example, the parameter is resistivity. In one example, the parameter is acoustic velocity.

Abstract: A walkaway VSP survey is carried out with receivers located in a borehole near the base salt. Reflection tomographic inversion of data from the walkaway VSP is used to derive a velocity model for the subsurface and may be used for imaging of sub-salt reflections.

Abstract: The invention is a method, having applications for the development of reservoirs, for predicting the production of an underground reservoir, comprising generating and updating a parameterized geologic model from production data and seismic data and in particular 4D seismic data which may be used in development of oil reservoirs. According to the method, production data are simulated from the geologic model and a flow simulator, and a petro-elastic depth model is deduced therefrom. A depth/time conversion model is then defined, by means of which the petro-elastic model is converted into time. The model is adjusted by correcting the lag induced by the depth/time conversion and by recalibrating the model. The geologic model is optimized by comparing, through an objective function, the real measurements with the simulation responses (production responses and seismic attributes in time) by updating in particular the depth/time conversion model.

Abstract: Seismic data recorded by subsurface seismic sensors placed in a borehole, such as an oil or gas well, are transformed via a process of upward wavefield propagation to pseudo-receivers at the surface of the earth. The seismic data thus transformed can be processed as though the data had been recorded by the pseudo-receivers at the surface rather than in the borehole where the data were actually recorded. This method accurately accounts for seismic source statics, anisotropy, and all velocity effects between the real receivers in the borehole and the pseudo-receivers at the surface of the earth.

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 behaviour 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 technique includes providing seismic data acquired in a seismic survey of a medium. The seismic data includes particle motion data. The technique includes modeling waves propagating through the medium during the survey as a function of at least one property of the medium and the seismic data. The technique includes, based on the modeling, determining the property(ies) of the medium.

Abstract: A method for generating a synthetic seismogram. In one implementation, the method may include generating a first seismogram in a tau-p domain for a wavefront that moves through an overburden to an upper boundary of a reservoir. The first seismogram is based on a common shot point gather. The method may further include generating a second seismogram in the tau-p domain for the wavefront moving from the upper boundary to a lower boundary of the reservoir and reflected back up to the upper boundary; generating a third seismogram in the tau-p domain for the wavefront moving from the upper boundary of the reservoir through the overburden; and adding the first seismogram in the tau-p domain, the second seismogram in the tau-p domain, and the third seismogram in the tau-p domain.

Abstract: A method for generating a synthetic seismogram. In one implementation, a ray tracing may be performed on a subsurface. The ray tracing may generate a plurality of rays. A first seismic wavefront by may be reconstructed by triangulating a first plurality of control points that correspond to the plurality of rays. Each control point may represent an end point of a ray at the first seismic wavefront. The plurality of rays may be propagated to a second seismic wavefront. The second seismic wavefront may have a hole associated with at least one missing ray at the second seismic wavefront. A plurality of points on a circle may be defined that correspond to a second plurality of control points defining the hole. The second seismic wavefront may be reconstructed based on the plurality of points on the circle.

Abstract: The invention is a method for inferring the saturation and pressure change of a reservoir by combining the information from 4D (time-lapse) seismic and time lag data volumes (7) derived from the 4D seismic, well logs (4), and reservoir simulation results (when simulator results are available) and featuring one or more 4D well ties (1) for a quantitative 4D interpretation. The inventive method uses model-based inversion incorporating rock physics (2) at well locations (5), and is statistical-based (6) away from wells. The method thus allows integration (8) of rock physics model and reservoir simulation and honors 4D seismic change.

Abstract: Described is a finite-difference methodology for efficiently computing the response from a model subject to changes within sub-volumes with the sub-volume enclosed with an extrapolation surface within an injection boundary using Green's functions to update the injection boundary and transmitting an updated wavefield from the injection boundary back into the altered sub-volume to include higher order reflections from outside of the altered sub-space.

Abstract: The present invention incorporates the use of model-driven and data-driven methodologies to attenuate multiples in seismic data utilizing a prediction model which includes multiply-reflected, surface-related seismic waves. The present invention includes beam techniques and convolving a predicted multiples beam with a segment of a modeled pegleg beam to obtain a convolved multiples beam. The convolved multiples beam can then he deconvolved to attenuate the multiples that are present in the original input beam.

Abstract: A seismic velocity profile in a region of interest in a subsurface formation is determined using at least the following steps. (a) Activating a seismic source at a location n, thereby exciting a wave in the subsurface formation. (b) Recording a wave signal trace unm(t) against time t, at a seismic receiver m. (c) Recording a wave signal trace unk(t) against time t at a seismic receiver k. (d) Cross correlating the wave signal traces unm(t) and unk(t) to obtain uconvnmnk(t). (e) Repeating these steps, for different locations n; (f) Summing uconvnmnk(t) over all locations n, to obtain a signal trace uvsmk(t) which corresponds to the signal received by the seismic receiver k from the virtual source at the position of seismic receiver m; (g) Deriving the seismic velocity based on the time of first arrival of the wave in uvsmk(t) and the predetermined distance between the seismic receiver m and the seismic receiver k.

Abstract: A method and computer instructions on computer readable media for determining and analyzing spatial changes in the earth's subsurface associated with dip vectors measured using 3D data in regions near a fluid contact or seismic flat spot event. The method obtains seismic attribute data, then derives corresponding 3D dip and azimuth as a 3D volume and derives corresponding 3D reliability volumes or 3D censor volumes. A set of vector is formed within a local subvolume of interest interior to the focused subvolume of interest for each reliability location, and a subset of local vectors within a user specified deviation of the azimuth of the structural dip vector are identified. A set of candidate flat spot dip vectors within the local subvolume of interest are identified enabling a significance measure for each vector within the set of candidate flat spot dip vectors to be determined.

Abstract: In various embodiments, the present disclosure describes methods for processing seismic data to concurrently produce a velocity model and a depth image. Various embodiments of the methods include: a) acquiring seismic data; b) generating a shallow velocity model from the seismic data; c) generating a stacking velocity model using the shallow velocity model as a guide; d) generating an initial interval velocity model from the stacking velocity model; and e) generating an initial depth image using the initial interval velocity model. The methods also include iterative improvement of the initial depth image and the initial interval velocity model to produce improved depth images and improved interval velocity models. Improvement of the depth images and the interval velocity models is evaluated by using a congruency test.

Abstract: Method for migration of seismic data into datasets having common azimuth angle at the reflection point. A velocity model is selected that prescribes subsurface P and/or S wave velocities including any required anisotropy parameters. (41) For shot locations on a surface grid, rays are traced on to a 3D grid of points in a target region of the subsurface. (42) At least the travel times of the rays and their dip angles at each subsurface point are stored in computer memory as they are computed. (43) Using the stored ray maps, the seismic data are migrated into seismic image volumes, each volume being characterized by at least an azimuthal angle bin, the azimuthal angles being computed from said ray dip angle information.

Abstract: Compressional and shear velocities of earth formations are measured through casing. The determined compressional and shear velocities are used in a two component mixing model to provides improved quantitative values for the solid, the dry frame, and the pore compressibility. These are used in determination of hydrocarbon saturation.

Abstract: Method for reducing instability and increasing computational efficiency in tomographic inversion for velocity model building. A system of tomographic equations is developed for a uniform grid. A non-uniform parameterization is found for which a linear mapping exists between the space of the uniform grid and the space of the non-uniform grid. The matrix that relates velocity to the tomographic data in the non-uniform representation is then given by the matrix product of the corresponding matrix in the uniform grid representation and the mapping matrix. Inversion can then be performed for the non-uniform parameterization on a smaller, more stable matrix.

Abstract: Diagonal gather trace interpolation systems and methods are disclosed. In some embodiments, the method includes obtaining seismic traces from a marine seismic survey performed using typically two seismic sources fired in a flip-flop pattern. The seismic traces are processed in common field file trace groups from each cable by performing trace interpolation in opposing diagonal directions. Among other things, diagonal trace interpolation may improve azimuthal regularization. In any event, the disclosed interpolation methods maintain spatial bandwidth increased spatial resolution with increased inline and crossline sampling components. Diagonal gather trace interpolation exploits reduced input trace separation to provide improved stability and detection of a greater range of formation dip angles. After interpolation and regularization, the seismic traces may be imaged and interpreted for improved seismic exploration and monitoring.

Abstract: Methods and systems for detecting changes of a fluid in a subterranean reservoir, wherein at several points in time, data are collected with the aid of a passive method in which low-frequency acoustic signals are passively measured by means of acoustic sensors. Changes in the fluid can be monitored in a simple and cost efficient way when these data are overlaid with static 3D data, which were collected with the aid of a reflection-seismic method so that a time-related representation of the change of the fluid is possible.

Abstract: The present invention provides methods and systems for microseismic hydraulic fracture monitoring in real-time. The methods and systems of the present invention may include continuous map migration of recorded microseismic signals. The methods and systems provide robust automated simultaneous detection and location of microseismic events.

Abstract: This patent deals with methods to selectively excite and analyze the resonance phenomena existing in an enclosed oil, gas and or water reservoir, thereby locating its presence, by doing qualitative and quantitative estimates of its extent via forward modeling. The oil, gas or water reservoir is represented as a fluid filled crack system or as a fluid saturated sponge located in solid rock. This patent covers the actively excited response and details methods to optimize the excitation. Due to interaction between either fluid filled fractures or fluid saturated rock lenses and the surrounding rock, the incident seismic energy is amplified in specific frequency ranges corresponding to the resonance frequencies of such systems. Measurements are made over the survey area, singly or in arrays. These are first used to determine qualitatively the resonance behavior, by relating them to resonance signal sources and possibly their direction. Overall statistical analysis assesses dominant frequencies in the spectrum.

Abstract: A method for obtaining enhanced seismic data and optimized inverted reflectivities includes computing statistical well characterizations based upon band-limited well reflectivities for a subsurface region. Sets of processed seismic data are computed by applying differing processing sequences to seismic data corresponding to the subsurface region. Inverted reflectivities are computed by inverting the sets of processed seismic data. Statistical seismic characterizations are computed based upon the inverted reflectivities. Statistical difference measurements (SDMs) are computed between the statistical well and seismic characterizations. An optimal processing sequence is selected based upon the computed SDMs. Enhanced seismic data is obtained by processing the seismic data corresponding to the subsurface region. An optimal seismic inversion algorithm is obtained based upon the computed SDMs.

Abstract: A method for quantitatively evaluating and using multiple geophysical datasets and external constraints for performing velocity model building through simultaneous Joint Inversion and finalized at the improvement of seismic depth images in particularly difficult geology and hydrocarbon high-risk exploration areas is disclosed, which involved the development of techniques: to derive an iterative depth-domain seismic imaging workflow which allows for the simultaneous use of seismic post-migration Common Image Gather residuals together with first arrival (First Break) residuals in conjunction with gravity data and magnetotelluric data; to include in the iterative Joint Inversion workflow the setup of external a-priori constraints as well as of external constraints weighted by probability functions; to include in the iterative Joint Inversion workflow the probabilistic evaluation of the relationships among geophysical parameters that are distinguished into analytical, empirical and structural (i.e.

Abstract: A technique includes modeling interpolated seismic measurements as a random process characterized by seismic measurements acquired at a set of sensor locations and an interpolation error. The technique includes determining the interpolated seismic measurements based at least in part on a minimization of the interpolation error.

Abstract: A walkaway VSP survey is carried out with receivers located in a borehole under a salt overhang. Redatuming of the multicomponent data to virtual sources in the borehole followed by vector Kirchhoff migration using a simple velocity model provides an accurate image of the salt face.

Abstract: A method for updating a velocity model of a subsurface of the earth is described herein. A tomographic update to the velocity model of the subsurface may be performed to generate a tomographic velocity model update. A geomechanical velocity model update of the subsurface may be calculated. The geomechanical velocity model update may be combined with the tomographic velocity model update.

Abstract: Method for designing a converted mode (PS or SP) seismic survey to accomplish specified vertical and lateral resolution objectives at target depth. An equation (181) is provided for determining the minimum bandwidth required for a desired vertical resolution at a selected scattering angle, as a function of incident and reflected wave velocities, one of which is the P-wave velocity and the other is the S-wave velocity. A second equation (182) is provided for determining migration acceptance angle from the desired vertical and lateral resolutions. Source and receiver apertures may then be determined by ray tracing. Finally, a third equation (183) is provided for the maximum bin size to avoid aliasing, given the migration acceptance angle and a maximum frequency needed to achieve the bandwidth requirement. Source and receiver spacing may then be based on the maximum bin size.

Abstract: Method for building a subsalt velocity model. In one implementation, the method may include determining a velocity of a sedimentary area surrounding a salt body, determining an initial velocity of a subsalt sedimentary area disposed below the salt body by interpolating the velocity of the surrounding sedimentary area with one or more boundaries defining the salt body, and updating the initial velocity of the subsalt sedimentary area.

Abstract: A method for providing a velocity profile for a subsurface region that includes the reflective interfaces, the method comprising the steps of: providing a set of data comprising signals transmitted by a transmitter and collected at a receiver, wherein the data include a primary signal that has been reflected off of one of the reflective interfaces and a multiply-reflected signal that has been reflected off of at least two of the reflective interfaces, providing a velocity model for the subsurface region, using the velocity model and the primary signal to construct a first image of the subsurface region, using the velocity model and the multiply-reflected signal to construct a second image of the subsurface region, determining a measure of match between the first and second images, adjusting the velocity model based on this measure, and repeating the steps until the measure of match attains a desired level.

Abstract: A method for interpreting seismic data below a salt layer includes depth migrating the seismic data to a bottom of the salt layer. The migrating including generating an initial model of velocities below the salt layer. The initial model is scaled by a plurality of scale factors at at least one image position. At least one of the plurality of scale factors for which a depth migrated image below the salt layer is optimum is selected as the scale factor.

Abstract: A method for acquiring and analyzing time-series data using singularities is described. This method allows for the analysis of data over a wide spectrum of frequencies. Once the data is acquired in an oil field, singularities of the data are extracted; and the extracted singularities are utilized to interpret the formation properties related to the data.

Abstract: A technique for performing a fast residual migration of seismic data through parsimonious image decomposition is presented. In one aspect, the technique includes a software-implemented method for processing a set of seismic data includes through parsimonious image decomposition. Other aspects of the technique include a program storage medium encoded with instructions that, when executed by a processor, perform such a method or a computing apparatus programmed to perform such a method.

Abstract: The invention relates to a method for fracture plane reconstruction in a three-dimensional set (20) of values, comprising the steps of providing a computer with the three-dimensional set, display by the computer of a succession of plane sections (10) of the three-dimensional set, selection by the user of points of the fracture plane over some of these sections during their display; and reconstruction by the computer of the fracture plane from the selected points.

Abstract: In general, in one aspect, the invention relates to a method for determining properties of a subterranean formation.