Newer OPDs were prepared electronically and converted to Adobe.
Older OPDs were prepared on mylar with manual cartographic methods and then scanned into Adobe. Shoreline planimetric detail is shown when it falls within the limits of a diagram. OPD sheet names relate to land features, or to hydrographic features contained within the limits of the diagram. OPD names usually coincide with standard topographic sheet names when diagrams include land areas. The OPDs are numbered using the United Nations International Map of the World Numbering System. Geological Survey topographic map series.
OPD limits usually approximate the standard 1:250,000 scale U.S. However, in areas further offshore where Leasing Maps have never been generated, the Official Protraction Diagram (OPD) is used.Ī standard OPD is 1 degree in latitude by 2 degrees in longitude (at lower latitudes: 0 - 48 degrees) as in the Gulf of Mexico. Because the Leasing Maps reflect so many active leases, they are still being maintained. This has created a wide variety of Leasing Maps in projection, shape and overall size, but the blocks remained consistent, and are never larger than the 5760 acres.
Leasing Maps were created as oil/gas leasing expanded offshore of Texas and Louisiana.Įventually the Leasing Maps were projected so far offshore that negative coordinates were required to support the projection. An older format, known as the Leasing Map, was based on Texas or Louisiana State Plane mapping projections. Within the Gulf of Mexico, there are two types of maps that depict blocks that could be leased.