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Abstract: Making Better Structure Maps by Combining Direct Mapping and Conformable Mapping Techniques: An Example from the United States Naval Petroleum Reserve No. 1, Elk Hills, CA


Typical structure maps are made one of two ways, directly contouring the surface using available data points perhaps with the use of dip data or adding/subtracting an isochore from a previously made structural surface. The first method, here called the Direct Mapping Method, emphasizes structural data and interpretation, the second, here called the Conformable Mapping Method, emphasizes stratigraphic facies interpretation and can also aid in mapping deeper horizons that may have less well control. Each method has its own strengths and advantages and, if they are combined, a better interpretation can result reflecting both structural and stratigraphic input from the geologist

There are several ways to combine these two mapping methods using a computer mapping program. The first way is to model each independently, freeze the two interpretations in mutually exclusive areas, and then merge them together. Another way is to overlay the two maps (as contours) and then hand edit them into one interpretation. A third way is to take an average of the two maps - calculate the difference between the grids, divide by two and add/subtract from one of the grids. A fourth way is to contour one using the form of the other as a guide with a technique called trendform gridding. These methods will be discussed using examples from the Northwest Stevens structure of the Elk Hills field.

Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California