1995 National Oil and Gas Assessment Conventional Plays within the Western Great Basin Province

The purpose of these files is to illustrate the geologic boundary of
the play as defined for the 1995 U.S. National Assessment. The play
was used as the fundamental assessment unit.

The fundamental geologic unit used in the 1995 National Oil and Gas
Assessment was the play, which is defined as a set of known or
postulated oil and or gas accumulations sharing similar geologic,
geographic, and temporal properties, such as source rock, migration
pathways, timing, trapping mechanism, and hydrocarbon type. The
geographic limit of each play was defined and mapped by the geologist
responsible for each province. The play boundaries were defined
geologically as the limits of the geologic elements that define the
play, such as the limits of the reservoir rock, geologic structures,
source rock, and seal lithologies. The only exceptions to this are
plays that border the Federal-State water boundary. In these cases,
the Federal-State water boundary forms part of the play boundary. The
play boundaries were defined in the period 1993-1994.

Conventional oil and gas plays within province 18 (Western Great
Basin) are listed here by play number and name:

Number Name
1801 Hornbrook Basin-Modoc Plateau
1802 Eastern Oregon Neogene Basins
1803 Permian-Triassic Source Rocks Northwestern Nevada
and East Central and Eastern Oregon
1804 Cretaceous Source Rocks, Northwestern Nevada
1805 Neogene Source Rocks, Northwestern Nevada and Eastern California