Volume Based Curvature Computations Illuminate Sub-Seismic Features: Fractures, Faults, Channels, Reefs

Volume Based Curvature Computations Illuminate Sub-Seismic Features: Fractures, Faults, Channels, Reefs

Charles (Chuck) Blumentritt & Mark A. Stevenson

Geo-Texture Technologies

Abstract

Volumetric curvature analysis is a simple but computationally intensive procedure that provides insight into fracture orientation, illumination of channels and subtle reefs. Until recently, curvature has been limited to computation along horizon surfaces that may be affected by unintentional bias and picking errors introduced during the interpretation process. Volumetric curvature is accomplished in a two-step process. In the first step, a moving analysis operator measures reflection dip and azimuth that represents the best single dip for each sample in the full volume. In the second step, we calculate curvature from adjacent measures of dip and azimuth. We use both long and short curvature analysis windows to estimate multiple wavelength curvatures. This technique allows us to output full 3-D volumes of curvature values at one or more scales of analysis. We apply these techniques to data sets and find lineaments not observed with other seismic attributes. These examples demonstrate the potential of this new technology to determine stress regimes and predict azimuths of open fracture systems at any time or stratigraphic position within a 3-D cube. This provides a new and rapid method of seismically analyzing fracture reservoirs.

Before curvature processing begins, the post-stack data volume undergoes a data conditioning algorithm we call Principal Component Analysis, which removes noise and sharpens the data. The resulting SEG-Y volume is then used as the input for the volumetric curvature processing routine. This data conditioning process has proved to be a valuable stand-alone product for attenuating noisy data – even for clients not interested in volumetric curvature processing.

Charles Blumentritt (Presenter)

Geo-Texture's Chief Geoscientist Charles Blumentritt received a BS in Geophysical Engineering from St. Louis University. He then spent over 28 years as a geophysicist with Amoco, working in a “hands on” capacity in all aspects of geophysical exploration including acquisition, processing, technical projects, interpretation and potential fields.

He has worked both exploration and development projects in the Rocky Mountains, Alaska, Tunisia, Egypt, UAE-Oman, Trinidad, Mexico, and the Gulf of Mexico. During his career at Amoco, he kept his knowledge and skills current by taking numerous in-house training courses, participating in company-wide technical transfer groups, and graduate study at the University of Houston.

Upon his retirement from Amoco, Mr. Blumentritt returned to the University of Houston, enrolled as a Ph.D. student in Geology. As part of his research there, he helped develop and implement the newly developed technology of volume-based curvature attributes for 3D seismic data. As a result of his expertise in volume-based curvature technology, Mr. Blumentritt was recruited to head Geo-Texture's geoscience team, where he has supervised the processing and interpreted the results of over 500 curvature projects.

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