Assessing
Undiscovered Resources of the Barnett-Paleozoic Total
Petroleum
System
, Bend
Arch–Fort Worth Basin Province
By
Richard M. Pollastro1, Ronald J. Hill1, Daniel M. Jarvie2, and Mitchell E. Henry1
1U.S. Geological Survey, Denver, CO; 2Humble Geochemical Services, Humble, TX
Organic-rich, Barnett Shale (Mississippian) is the primary
source rock for oil and gas produced from Paleozoic reservoirs in the Bend
Arch–Fort Worth Basin Province. Distribution and geochemical typing of
hydrocarbons in this mature petroleum
province indicates generation and
expulsion from the Barnett at a depocenter coincident with a paleoaxis of the
Fort Worth Basin. Barnett-sourced hydrocarbons migrated westward into reservoirs
of the Bend Arch and Eastern shelf; however, some oil and gas was possibly
sourced by a composite Woodford-Barnett
petroleum
system
of the Midland Basin
from the west.
Current U.S. Geological assessments of undiscovered oil and gas
are performed on Total Petroleum
Systems (TPS) that include mature source rock,
known accumulations, and area(s) of undiscovered hydrocarbon potential. The TPS
is subdivided into Assessment Units based on similar geologic conditions and
accumulation type. Assessment of the Barnett-Paleozoic TPS focuses particularly
on the continuous Barnett accumulation. Barnett shale gas will be assessed after
mapping “sweet spots” and outlying areas of potential, and by defining
distributions of drainage (cell) size and cell estimated ultimate recovery. An
example of a Barnett “sweet spot” is the Greater Newark East area where
thick, siliceous Barnett has reached the gas window, and overlain and underlain
by impermeable limestones that serve as “frac” barriers. Assessment Units
are also identified for mature conventional plays in Paleozoic carbonate and
clastic reservoirs, such as the Chappel Limestone pinnacle reefs and Bend Group
conglomerate, respectively. However, Barnett continuous gas is expected to add
the greatest volume of undiscovered, technically recoverable resource.
AAPG Search and Discovery Article #90010©2003 AAPG Southwest Section Meeting, Fort Worth, Texas, March 1-4, 2003