TECHNICAL FIELD

The present description relates generally to seismic data interpretation, and more particularly, to the interpretation of multiple Z-valued horizons from seismic data for geological structure modeling.

BACKGROUND

For purposes of hydrocarbon exploration and production, knowing the properties and locations of underground rock formations is useful for making decisions as to where and how to economically produce hydrocarbons from underground reservoirs. Seismic reflection surveys of both onshore and offshore hydrocarbon bearing formations are often performed to collect seismic data that may be used to gain an understanding of the particular geological structure of each formation. For example, such data may be used to identify geological features, such as horizons and faults, within a volume of a subsurface formation. Seismic reflection is a technique of generating seismic waves and measuring the time taken for the seismic waves to travel from the source of the waves, reflect off subsurface geological features, and be detected by an array of receivers at the surface. Each receiver's response to a single shot of seismic energy is known as a trace and is recorded for analysis. In land acquisition, seismic waves are transmitted from the surface, produced either mechanically or by explosive device. Resulting reflections from the subsurface are received at geophone sensors. In marine data acquisition surveying geological structures underlying a body of water, a water-going vessel is utilized to tow acoustic sources and seismic streamers supporting an array of hydrophones to detect reflected seismic waves.

Interpretation of seismic reflection surveys often involves analyzing multiple volumes of seismic data to identify geological structures and stratigraphic features of the subsurface formation. To facilitate such seismic data analysis, seismic interpretation tools are available for a geophysicist to “pick” horizons and other stratigraphic features within a volume of a seismic data. However, the interpretation of subsurface geological structures that have relatively complex geometries within a seismic volume can become a tedious and time-consuming process for geophysicists using conventional seismic interpretation tools. Examples of such complex geological structures include, but are not limited to, reverse faults, overturned beds, salt bodies, and any other structure for which different portions of the structure intersect the same seismic trace multiple times. Such a complex structure may be referred to as having multiple Z (or “multi-Z”) points at the same X and Y location within a three-dimensional (3D) X, Y and Z coordinate space of a 3D seismic volume, where Z is the depth axis through the seismic volume. Each intersection point along the Z-axis may be associated with a different surface of the same multiple Z-valued horizon to represent the complex structure. The interpretation of such a multi-Z horizon using conventional tools generally requires multiple, overlapping horizons or horizon segments to be manually selected or “picked” from the seismic data and then, patched together so as to represent what is actually a single geological structure or event. Furthermore, any changes to the conventional interpretation may require manual updates to each of its constituent segments.

