A method of obtaining a relative amplitude preserved seismic volume acquired in a time-domain for a subterranean region of interest and transforming it into a low-frequency monospectral amplitude volume. The method further determines a seismic attenuation volume from the relative amplitude preserved seismic volume acquired in the time-domain. Furthermore, the method generates a low-frequency monospectral amplitude map for a surface of interest by averaging the low-frequency monospectral amplitude volume over a depth-window around the surface of interest, and generates a seismic attenuation map for a surface of interest by averaging the seismic attenuation volume over a depth-window around the surface of interest. The method further determines an attribute map based on the seismic attenuation map and the low-frequency monospectral amplitude map for the surface of interest, and determines a presence of gas in the subterranean region of interest based on the attribute map.

The present disclosure relates to the field of geophysical processing methods for oil and gas exploration, and more particularly, to a method for gas detection using multiple quantum neural networks. A plurality of stratigraphic and structural seismic attributes are extracted from the seismic data of a target horizon, and input seismic characteristic parameters are divided into different classes by using an unsupervised learning and supervised learning combined quantum self-organizing feature map network. Gas detection is then performed using a particle swarm optimization based quantum gate node neural network with clustering results of various seismic characteristic parameters output by the quantum self-organizing feature map network as inputs. The present method uses the unsupervised learning and supervised learning combined quantum self-organizing feature map network for a plurality of stratigraphic and structural seismic attributes of the seismic data and thus has improved accuracy and uniqueness of clustering.

A method and system for prospecting for gas hydrates and gas hydrates over free gas is disclosed. The method includes using well log data to form a rock physics model to generate synthetic seismic representing hydrate and hydrate-over-gas models. Spectral decomposition is applied to the synthetic seismic and to field seismic from the prospecting area, forming low frequency narrow band data sets. From mapped potential sands in the field data, compare positive amplitude dominated event in the narrow band field data to the narrow band synthetics for gas hydrates. Compare negative amplitude dominated event in the narrow band field data to the narrow band synthetics for gas or gas hydrate-over gas. From these comparisons, perform modeling to determine saturation and thickness for hydrates and hydrates-over-gas.

A flow field measurement device and a method for a scale model of a natural gas hydrate reservoir are provided. The measurement device includes non-central vertical well pressure sensors, non-central vertical well outlet valves, communicating vessel valves, differential pressure sensors, a communicating vessel, a central vertical well outlet valve, and a central vertical well pressure sensor. By providing differential pressure sensors, between a measuring point of the central vertical well and a measuring point of each of the non-central vertical wells, to measure pressure differences, the flow field measurement device enables a reasonable distribution of a three-dimensional space inside the reactor to analyze gas-liquid flow trends in the reactor with a simulated flow field. Determining whether to turn on the differential pressure sensors according to a predetermination based on a feedback from the pressure sensors, allows flow field measurements in the reactor under both high and low pressure differences.

The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems for direct gas reservoir detection using frequency amplitude. One computer-implemented method includes spectrally decomposing seismic data associated with a target area into a plurality of mono-frequency volumes. Further, the method includes based on a low-frequency volume of the plurality of volumes, generating a low frequency map of the target area. Yet further, the method includes based on a high-frequency volume of the plurality of volumes, generating a high frequency map of the target area. Additionally, the method includes dividing the low frequency map by the high frequency map to generate a frequency ratio map. The method also includes using the frequency ratio map to identify a subsurface gas reservoir in the target area.

A flow field measurement device and a method for a scale model of a natural gas hydrate reservoir are provided. The measurement device includes non-central vertical well pressure sensors, non-central vertical well outlet valves, communicating vessel valves, differential pressure sensors, a communicating vessel, a central vertical well outlet valve, and a central vertical well pressure sensor. By providing differential pressure sensors, between a measuring point of the central vertical well and a measuring point of each of the non-central vertical wells, to measure pressure differences, the flow field measurement device enables a reasonable distribution of a three-dimensional space inside the reactor to analyze gas-liquid flow trends in the reactor with a simulated flow field. Determining whether to turn on the differential pressure sensors according to a predetermination based on a feedback from the pressure sensors, allows flow field measurements in the reactor under both high and low pressure differences.

A method of obtaining a relative amplitude preserved seismic volume acquired in a time-domain for a subterranean region of interest and transforming it into a low-frequency monospectral amplitude volume. The method further determines a seismic attenuation volume from the relative amplitude preserved seismic volume acquired in the time-domain. Furthermore, the method generates a low-frequency monospectral amplitude map for a surface of interest by averaging the low-frequency monospectral amplitude volume over a depth-window around the surface of interest, and generates a seismic attenuation map for a surface of interest by averaging the seismic attenuation volume over a depth-window around the surface of interest. The method further determines an attribute map based on the seismic attenuation map and the low-frequency monospectral amplitude map for the surface of interest, and determines a presence of gas in the subterranean region of interest based on the attribute map.

A method that includes transforming a relative amplitude preserved 3D seismic volume acquired in the time-domain into a plurality of isofrequency volumes, extracting from the plurality of isofrequency volumes a first isofrequency spectral amplitude volume and a second isofrequency spectral amplitude volume. The method further includes determining an attribute volume from the two isofrequency spectral amplitude volumes, and determining a presence of gas in a subterranean region of interest based on the attribute volume.

The application relates to the technical field of oil and gas field development, and discloses a correction method and system for a permeability model considering gas hydrate distribution, and a method and system for determining the permeability of the hydrate-bearing porous medium. The correction method includes: calculating a water mass and a hydrate saturation of each subregion of a porous medium in a dissociation process of a gas hydrate; calculating an average permeability of the porous medium in the dissociation process of the gas hydrate according to the hydrate saturation and a permeability model, wherein a value of a permeability characteristic parameter in the permeability model is an initial value of the permeability characteristic parameter; and determining the initial value of the permeability characteristic parameter as an optimal value of the permeability characteristic parameter under a condition that an difference between the average permeability of the porous medium and an actually measured permeability in the dissociation process of the gas hydrate is less than or equal to a preset value. In the application, through the corrected permeability model, the permeability characteristics of the porous medium considering the heterogeneous distribution of the hydrate can be accurately measured.

The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems for direct gas reservoir detection using frequency amplitude. One computer-implemented method includes spectrally decomposing seismic data associated with a target area into a plurality of mono-frequency volumes. Further, the method includes based on a low-frequency volume of the plurality of volumes, generating a low frequency map of the target area. Yet further, the method includes based on a high-frequency volume of the plurality of volumes, generating a high frequency map of the target area. Additionally, the method includes dividing the low frequency map by the high frequency map to generate a frequency ratio map. The method also includes using the frequency ratio map to identify a subsurface gas reservoir in the target area.