A SIMPLE MEANS FOR DRAWING HYPERBOLIC AND CONCENTRIC POSITION-CHARTS FOR USE IN OIL EXPLORATION OF THE CONTINENTAL SHELF

Clayton Nielsen

Peer Reviewed

Abstract:	ELECTRONIC POSITIONING SYSTEMS are used extensively as one of the many tools that aid in the search for oil under the continental shelf of the Gulf of Mexico. More areas will be opened for oil exploration in the future and Ohis means a future increase in the use of electronic positioning systems. A fundamental requirement for oil exploration and exploitation is that the geophysical and geological data suffer as small a horizontal distortion as possible, both in profile and contour forms, as a result of positioning errors. Second, the absolute position, say, of a particular sub-bottom feature, must be so established that it can be re-located without difficulty. Plotting charts, provided at a usable scale, are an important factor in these requirements. Small-scale plotting charts having the necessary lattice-work of positioning lanes that allow a logical small-scale exploratory pattern are easily obtained. Obtaining large-scale charts showing a small surface area, however, can be a problem, both in time and cost, because projecting and drafting the lattice work is a complicated process that has always required the services of a cartographer using specialized equipment. Large-scale charts, however, are a necessary adjunct for showing bottom features, geophysical data, etc. The difficulty in constructing large-scale positioning charts can be greatly reduced by standard tables, such as those present’ly used in constructing latitudes and longitudes on standard map projections. It was previously impossible to formulate such tables because the location of the transmitter antennas, which are the basis for a lattice net, are not constants like the earth’s equator or the prime meridian but rather vary from net to net. The U.S. Naval Oceanographic Office has formulated standard t.ables that, enable noncartographic personnel to draft an electronic positioning lattice chart aboard ship, whenever such a chart is needed, using only a straight-edge, a gridded sheet, a pen, and the tables. These tables, presented with easy-tofollow “cook-book” instructions, are so simple to use that any member of the exploration team, untrained as he may be in cartographic methods, can plan and draft the required positioning chart irrespective of scale, area, or time. These tables allow the ship to construct charts on an efficient and timely basis and thus be able to conduct any closely spaced exploratory survey that may be dictated by the preliminary data.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 16, Number 3
Pages:	284 - 294
Cite this article:	Nielsen, Clayton, "A SIMPLE MEANS FOR DRAWING HYPERBOLIC AND CONCENTRIC POSITION-CHARTS FOR USE IN OIL EXPLORATION OF THE CONTINENTAL SHELF", NAVIGATION: Journal of The Institute of Navigation, Vol. 16, No. 3, Fall 1969, pp. 284-294.
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