the Permian Basin of West Texas and Southeast New Mexico is about 400
kilometers from east to west and 480 kilometers from north to south. It is one
of the great continental basins of the United States, the southernmost of the
Williston Michigan Illinois Anadarko and Permian Basin. This Basin is an important
contributor to the strength of the US economy. Today at around two million
barrels of produced oil per day. The Permian Basin accounts for over 20
percent of US oil production. In spite of its importance most people are unaware
of the basin and its significance to the US economy, geologists separate the
Permian Basin into six sub-regions: Northwest Shelf, Central Basin Platform,
Delaware Basin, Midland Basin, Val Verde Basin and the Eastern Shelf.
This basin architecture is hidden beneath a relatively flat and arid
region where few people live.
Up to 8,000 meters or five miles of
sediment fills the basin. Most of the sediment in the Permian Basin was
deposited in Paleozoic time from Cambrian to Permian or from about 530 to
250 million years ago.
If the basin is filled with Cambrian,
Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian and
Permian sediments.
Then why do we call it the Permian Basin?
Perhaps it is because
it contains one of the world's thickest deposits of Permian sediments.
Permian sediments occupy about half the basin fill.
Permian age reservoirs also contain
the majority of trapped oil within the basin.
Permian Basin deposition history
can be classified into three major stages.
The first stage lasted from
Cambrian to Mississippian time, when a broad sag basin called the Tobosa Basin
existed in the Permian Basin region.
This was part of a broad shallow marine shelf
that defined the southern margin of North America.
In early Paleozoic time,
the Tabosa basin filled chiefly with carbonate and fine-grained clastic
sediments and ceased to exist as a distinct Basin after deposition of
platform limestones and black shales during the Mississippian time.
The second stage of basin development occurred in late Carboniferous
that is Pennsylvanian in time
when the Permian Basin region became tectonic reactive.
Collision of Laurentia and Gondwanaland
to form Pangea led to faulting and rupturing of
the Tobosa basin significant faulting tectonic uplift and deeply subsiding
basins formed in response to formation of the northwest southeast trending
ancestral Rocky Mountains.
The rising Central Basin uplift subdivided the
former to Bosa basin into the Midland and Delaware basins with adjoining shelf areas.
Pennsylvanian strata consists of cyclical shales, carbonates and
sandstones deposited in a broad spectrum of depositional environments
including sediment starved basins, shallow-marine carbonate shelves.
fluvial coastal plains and deltas.
The last stage in formation of the Permian Basin
happened in Permian time
300 to 250 million years ago
when the basin filled in completely
the Permian Basin region at that time lay near the equator
and hosted a broad spectrum of shallow marine depositional environments
from hypersaline sabkha to tidal flats, low-energy open-marine shelves
grainstone shoals, and shelf-edge reefs, that prograded into the basins.
Thick sequences of organic-rich shales, siltstones, sandstones, and limestone
filled in the deeper parts of the basin.
The great Permian reef and associated
units exposed in the Guadalupe Mountains National Park is a superb representative
of this stage in Permian Basin development.
Finally, in late Permian time
about 260 million years ago
the whole area became a huge sabkha and filled with thick evaporites.
since the first commercial hydrocarbon discovery in 1921
the Permian Basin area has produced significant volumes of oil and natural gas.
Hydrocarbon production peaked in the 1970s and declined for several decades
until new techniques of horizontal drilling and hydraulic fracturing of
organic-rich mudstones and associated fine-grained facies
led to greatly increased in the early 21st century.
it is now clear that several organic rich
sedimentary horizons in the Permian Basin contain hydrocarbon deposits.
The richness of these deposits combined with drilling and completion technology that
allows us to commercially extract oil and gas from them ensures that the
Permian Basin will be an important part of the US economy far into the future
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