Most large petroleum exploration companies are assembling digital files of exploration data that can be accessed routinely to produce operating base maps. These data include site data (wells, seismic, pipelines, etc) and boundary data (leases, political subdivisions). To associate these data with a ground reference system, survey details (such as section, township, and range) have been digitally captured for computer-generated display.

In the past all this information was stored as conventional coordinates, such as latitude and longitude. This information comes mostly from a variety of sources lacking detail or having inaccurate detail for determining correct conventional coordinates. In any geographic area there may be a number of conventional

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base map sources, each of which may show accurate internal spacial distribution, but be inaccurately located relative to the true coordinate geometry of the earth.

Problems ensue when attempts are made to display various data from different sources. Wells, leases, seismic, etc, may not be properly located with respect to each other or with respect to the digital base used.

One solution is to store the digital base in conventional coordinates and locate all other data as offsets to known points in the digital base such as the closest section corner. this is an adaption of the so-called "Legal Description" that is used to locate wells. Pseudo-"Legal Descriptions" can be computer-calculated where not directly available. Boundary data can be treated as a series of connected points that can accurately overlie the digital base map data. Compatibility for all data thus located is achieved regardless of the source or digital base from which the data is acquired. Revisions of the digital base do not require re-registration of other data.

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