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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 54 (1970)

Issue: 3. (March)

First Page: 557

Last Page: 557

Title: California Digital Mapping: ABSTRACT

Author(s): Charles E. Chambers

Article Type: Meeting abstract


The Utility Data Corporation, in a joint venture with several petroleum companies, is conducting a precision-mapping program across 50,000 sq mi of the State of California. Accurately located within the project area will be approximately 50,000 section corners and 26,000 historic wells.

The project area has been surveyed by use of high-altitude, high-resolution aerial photography. Within each of the 2,500 photographs, there are photo-identifiable USCGS and USGS monuments that were flagged prior to flight. These are referred to as basic control, and permit, through analytic photogrammetric procedures, positioning of other photo-identifiable points of interest appearing on the photograph to within ±5 ft of accuracy. These coordinates properly describe, both in latitude-longitude and in the state plane-coordinate system, the location of the point on the geoid.

The program provides a coordinated set of base maps throughout the project area. It provides an accurate area base map with various levels of accuracy in coordinating section and rancho corners; i.e., photo-identifiable (53%), projected/protracted (17%), and calculated (30%). When the positions of the section and rancho corners are refined, significant errors in well locations become apparent.

The end products of the project are a digital file and a graphic file. The digital file contains coordinates of section and rancho corners, historic wells, and other points of interest. The graphic file produces a 15-minute quadrangle, automatically plotted at a scale of 1 in. = 2,000 ft. The equipment currently used for plotting is a Gerber Plotter with optical head to achieve the optimum in edge sharpness.

The California computerized-mapping program is the first of its type and scope to be conducted for the petroleum industry. Implementation of the program acknowledges the impact of the computer upon exploration; further, it reflects the needs of the industry for accurate land-net data, although precision well-location data do not share an equal priority.

The basic program provides an accurate area base map which, if considered as an initial building block, can be used by other elements of a company with minimum costs for supplemental aerial photography in small selected areas. For example, once geodetic control has been established, an overflight at lower altitude provides the Pipeline Department with right-of-way profiles and detail maps, the Production Department with precision plant-inventory records, and the Tax Department with accurate taxing-boundary information. This information is in digital form on tape or cards, formated for introduction into the computer.

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Copyright 1997 American Association of Petroleum Geologists