Flat spot

Abstract: A method of determining the existence of and location of hydrocarbon and water fluid contacts by analyzing spatial changes in 3D seismic data. The method begins by obtaining seismic attribute data as a 3D data volume. Then the method derives 3D dip and azimuth as a 3D volume and deriving corresponding 3D reliability volumes or derives responding 3D censor volumes which are representative of portions of the volume within which a reliable dip and azimuth can be determined. A focused subvolume of interest within the 3D data volume is then selected. The method concludes by storing filtered 3D seismic attribute data within the filter half length in each 3D direction along with null values for all non-reliability locations outside the filter half length but within the focused subvolume of interest forming a 3D output volume.

Abstract: A method of determining and analyzing spatial changes in the earth's subsurface. The method includes obtaining seismic attribute data as a 3D data volume and obtaining corresponding 3D dip and azimuth as a 3D volume and obtain corresponding 3D reliability volumes or 3D censor volumes which are representative of portions of the volume within in which a reliable dip and azimuth can be determined. The gradient of the seismic attribute data in the direction of structural dip is formed using either a dot product methodology or a derivative methodology after interpolation onto the direction of structural dip. At non-reliability locations or locations where no gradient could be meaningfully computed null values are stored. High gradient values in narrow time or depth ranges which are both statistically significant relative to a background level and contiguous designate regions likely to be proximal to a fluid contact or seismic flat spot.

Abstract: The recent discovery of a giant oil field in the southeastern Beaufort-Mackenzie basin has brought this frontier area closer to oil production despite severe environmental conditions. The Amauligak field is a fault-bounded growth structure developed in the Kugmallit Trough, within deltaic deposits of the Beaufort Sea Shelf. Shelf construction occurred during the Late Cretaceous-Tertiary by repeated progradation of the Mackenzie River delta in response to rift-induced opening of the Canada basin and extension of the Kugmallit Trough. The Amauligak field contains oil and gas in multiple sandstone reservoirs of the Oligocene Kugmallit sequence. The upper sandstones are truncated by an unconformity and sealed by the overlying shales of the Miocene Mackenzie Bay sequence. Based on two-dimensional seismic coverage, the field was initially described as structurally simple. Interactive interpretation on Landmark and SIDIS workstations of a three-dimensional seismic program revealed the local structural complications, spatial configuration, and detailed structural elements of the field. Direct hydrocarbon indicators (DHIs), including amplitude anomaly, phase change, flat spot, and low-frequency zone, associated with a large gas cap were investigated using full amplitude-range and attribute-extraction methods. Interpretation of seismic data and correlation with well results suggest that a combination of structural, stratigraphic, and hydrodynamic factors are responsible for the appearance and distribution of Amauligak DHIs. On the amplitude displays, a flui contact is seismically mappable over the field, clearly separating the gas cap from the wet reservoir.

Abstract: PURPOSE:To improve a working speed by forming the flat spot of optional shape easily and continuously by providing the means which changes the combination of plural lenses and the intervals of mutual lenses and by moving the body to be worked in the longitudinal axial direction. CONSTITUTION:One direction of a laser beam 2 is compressed by passing through a convex lens 7 and concave lens 8 of the laser beam 2 and a flat spot is formed. In case of the gap between lenses 7, 8 being made in a parallel beam again after the laser beam 2 passing through the concave lens 8, it becomes the difference in the mutual focusing distances. The ratio of the major axis to the minor axis of the flat spot to be formed becomes same as the difference in the focusing distances of lenses 7, 8. Now by changing the concave lens 8 with the concave lens 9 having different focusing distance the necessary flat pot is formed. Also, by moving the body 5 to be worked at constant speed in the major axial direction of the flat spot by a moving means 11, the working trace 12 that the flat spot continues is obtd. and the work speed can be increased.