Methods and systems for identifying a pay zone in a subterranean formation can include: logging a well extending into the subterranean formation including measuring bulk density, compressional wave travel time and shear wave travel time at different depths in the subterranean formation; calculating elastic attributes including acoustic impedance and compressional velocity-shear velocity ratio at different depths in the subterranean formation; and displaying and analyzing the calculated elastic attributes to identify the low resistivity pay zones.

The present disclosure is directed to numerically estimating the shear modulus of Kerogen by using a combination of mineralogy from digital image analysis and sonic log analysis, when measured data on only one elastic constant (Bulk, Young's or P-wave modulus) is available. In some instances, elastic properties predicted from the digital images are compared with sonic, shear, and density logs, to estimate the shear modulus of kerogen. As a one-to-one correspondence is not expected between the core sub-samples and the rock unit sampled by the well logs, cross-property relations can be used to identify the suitability of the effective medium models and to iteratively determine the shear modulus of kerogen.

A method for establishing a geostress field distribution of slopes in canyon areas includes: obtaining a persistence ratio of a fracture surface based on a structural plane trace length and a rock bridge length of the fracture surface, and then obtaining a fracture stage of a crack according to progressive failure characteristics of rock mass, combining a character of the fracture surface to obtain magnitude and direction of a maximum principal stress, and establishing the geostress field distribution. The method is simple to operate, does not need to carry out geostress testing, does not need a large amount of manpower and material resources, does not need redundant fund investment, and can simply and effectively obtain geostress field data. Moreover, combining with the geostress field inversion technology, a large-scale geostress field distribution condition can be obtained, which can provide a basis for engineering site selection and engineering rock mass stability determination.

Method for characterizing subterranean formation is described. One method involves simulating a poroelastic pressure response of known fracture geometry utilizing a geomechanical model to generate a simulated poroelastic pressure response. Compiling a database of simulated poroelastic pressure responses. Measuring a poroelastic pressure response of the subterranean formation during a hydraulic fracturing operation to generate a measured poroelastic pressure response. Identifying a closest simulated poroelastic pressure response in the library of simulated poroelastic pressure response. Estimating a geometrical parameter of a fracture or fractures in the subterranean formation based on the closest simulated poroelastic pressure response.

A method for determining a thermal maturity image of a subterranean region and a non-transitory computer readable medium, storing instructions for executing the method, are disclosed. The method includes, obtaining a seismic dataset for the subterranean region of interest, obtaining a thermal maturity value for a plurality of core samples taken from different positions within the subterranean region, and obtaining a plurality of well log types from the core sampling location. The method further includes determining a calibrated rock physics model based on the plurality of well log types, determining a pore fluid type based on the calibrated rock physics model, and determining a thermal maturity model based on the plurality of core samples, on the pore fluid type, and on the plurality of well logs. The method still further includes determining the thermal maturity image of the subterranean region based on the seismic dataset and thermal maturity model.

A reverse time migration imaging method for cased-hole based on ultrasonic pitch-catch measurement, including: calculating a theoretical dispersion curve; expanding original Lamb data of two receivers into array waveform data based on phase-shift interpolation; establishing a two-dimensional migration velocity model including density, P-wave velocity and S-wave velocity of a target area; generating and storing a forward propagating ultrasonic wavefield for each time step; reversing a time axis; generating and storing a reversely propagating ultrasonic Lamb wavefield for the two receivers after phase-shift interpolation; calculating envelopes of the forward propagating ultrasonic Lamb wavefield and the reversely propagating ultrasonic Lamb wavefield; applying a zero-lag cross-correlation imaging condition to obtain reverse time migration imaging results; and applying Laplace filtering to suppress low-frequency imaging noises in the imaging results.

A computer-implemented method, and system implementing the method, are disclosed for computing a final model of elastic properties, using nonlinear direct prestack seismic inversion for Poisson impedance. User inputs and earth-model data is obtained over points of incidence of a survey region, at various angles of incidence. Various models are then computed that serve for lithology identification and fluid discrimination and take part in preliminary seismic exploration and reservoir characterization. Therefore, further refinement of these models is required due to changes in burial depths, compaction and overburden pressure, as they provide limitations for reservoirs on porous media. The further refinement using nonlinear direct prestack seismic model is performed on a system computer, which produces a final model of elastic properties. This model can then be applied for lithology prediction and fluid detection to identify potential targets of oil and gas exploration and estimating spots in unconventional shale gas applications.

Disclosed is an in-situ stress evaluation method based on a wellbore mechanical instability collapse, including: selecting a mechanical instability collapse wellbore section and classifying a data, obtaining a deep in-situ stress according to a structural strain coefficient, establishing a structural strain coefficient equation based on a wellbore stress critical equilibrium condition, obtaining the structural strain coefficient by using a least squares method and obtaining a horizontal principal stress, and estimating a reasonableness of the deep in-situ stress. The method selects data of the wellbore mechanical instability collapse and classify the data to establish a stress critical equilibrium equation based on a strain coefficient and solve an overdetermined equation based on a critical collapse formation information restriction, so as to obtain a maximum horizontal principal stress and a minimum horizontal principal stress.

Computer-implemented stratigraphic play quality generation is disclosed. Stratigraphic data can be processed from each of a plurality of respective data sources to generate conditioned stratigraphic data. From at least some of the conditioned stratigraphic data, attributes of at least one seismic sequence can be extracted, and at least one seismic surface and at least one structural element associated with at least some of the conditioned stratigraphic data can be determined. At least some of the conditioned stratigraphic data representing sedimentary layers can be correlated with seismic reflection data to ascertain a subsurface of the geologic area at a respective depth. Reservoir properties associated with the geologic area are linked to elastic properties, and a 2D model built. Moreover, 3D map can be generated that is usable for a prospective drilling plan.

A method for estimating all five transversely-isotropic (TI)-elastic constants using borehole sonic data obtained from at least one subterranean borehole in a transversely isotropic formation. In an embodiment, the method includes: solving for a quasi-compressional qP-wave velocity V.sub.qP using inversion algorithms based on exact solutions of the Kelvin-Christoffel equations for plane wave velocities in arbitrarily anisotropic formations, where the five TI-elastic constants may include C.sub.11, C.sub.13, C.sub.33, C.sub.55, and C.sub.66.