Abstract

The identification of different sedimentary structures in eolian dune deposits (particularly those resulting from grain flow) allows estimation of the depositional dip angles of some bedding planes. By combining this dip-angle estimation with the overall dip of the formation (derived from seismic data and well correlation) and the wellbore orientation of a deviated well, two possible bedding-plane azimuths for the grain-flow deposits can usually be defined. By choosing wells deviated in a suitable direction and by assuming that major dune slip faces have a 180 degrees range in possible dip azimuth centered around the regional formative wind direction, the cores can be oriented when the regional formative wind direction is known. Detailed data on bedding dip may thus be extracted from conventional unoriented cores in suitably deviated wells. This method can be used in conjunction with or in the absence of other core-orientation techniques and has been applied successfully in parts of the Rotliegendes Group of the southern North Sea. However, it may also be applied to any cored eolian dune deposits where a single regional wind direction has previously been determined and the well has a suitable deviation direction.

First Page Preview

First page PDF preview
You do not currently have access to this article.