Permian basin

Introduction

File:Val Verde Generalized Map.jpg

A regional map of the Permian Basin and adjacent geologic features. Note the Delaware and Midland basins, as well as the Central Basin Platform which separates them.

The Permian basin is a sedimentary basin known for its extensive petroleum and mineral resource deposits in western Texas and southeastern New Mexico in the United States. Active since the 1920s, the basin is the largest petroleum producing basin in the U.S. It accounts for thirty percent of U.S. crude oil production and more than forty percent of U.S. crude oil proved reserves at 9.8 billion barrels of oil. Stratigraphy plays a large factor in the basin's prolific production, as there are multiple hydrocarbon-rich units throughout the stratigraphic column. This provides the potential to develop multiple stacked producing zones from these different units. In addition to hydrocarbons, the Permian basin is also known for its significant potash deposits.

A stratigraphic column showing the upper stratigraphy of the Delaware Basin. The Bone Spring and Wolfcamp Formations - often commingled as the WolfBone - are the most productive plays in the basin, and are a large focus of unconventional prospecting. Many of the other formations are also hydrocarbon producing.

Stratigraphy

A stratigraphic column showing the upper stratigraphy in the Midland Basin. The Wolfcamp and Spraberry Formations - often commingled as the WolfBerry - are the most productive plays in the basin, and are a large focus of unconventional prospecting. Many of the other formations are also hydrocarbon producing.

The Permian basin is actually comprised of three separate components: the Delaware Basin, the Midland Basin, and the Central Basin Platform (Figure 1).

A stratigraphic column of the Central Basin Platform in the Permian Basin. The San Andreas Formation is historically the most important producing reservoir in this region, however many of the other formations also produce hydrocarbons. Image from Eleanor W. Smith.

A structural cross-section through the Permian Basin, displaying the structure and stratigraphic relationships between the Delaware basin (left), the Central Basin Platform, and the Midland basin (right). Note the slight nomenclature changes.

Due to differences in Depositional system and tectonic setting through time, each of these regions has it's own stratigraphic section and nomenclature. Figures 2-4 show stratigraphic columns of each region, with their distinct nomenclatures. Figure 5 displays a generalized cross-section through the larger Permian Basin, showing the structural high and slight stratigraphic differences between the Central Basin Platform and the Delaware and Midland basins.

Depositional Environment

Upper Cambrian to Mississippian

This period is characterized by passive margin tectonics following the post-rifting stage of the breakup of the Precambrian supercontinent Laurentia. There was significant shallow marine deposition into the ancestral Tobosa Basin during this time, resulting in thick shelf carbonate and shale accumulations.

Upper Mississippian to lower Permian

Most of the present day structural elements of the Permian Basin were formed during Variscan collision in the Upper Mississippian. This differentiated the Delaware and Midland basins with a central structural high, and led to significant siliciclastic deposition in the deeper basins, particularly in the Pennsylvanian. During the lower Permian, significant carbonate shelf deposits formed, particularly along the edges of the basins and in the Central Basin Platform. Carbonates such as these are exposed at the Capitan Reef outcrop locales in Guadalupe, Glass and Apache Mountains of New Mexico.

Upper Permian

Through the Permian, several kilometers of sediment accumulated in the Delaware and Midland basins. There are essentially five different types of deposits which correspond to the five sub-environments of deposition found in the region. The low-energy deep basin deposits are comprised primarily of organic-rich shales and siltstones, with occasional turbidite sheet sands. In the slope environment, a combination of shales and reworked shelfal sediments were deposited. The shelf margin environment is characterized by reworked transgressive sediment and high-energy carbonate buildups. The shallow marine shelf environment was dominated by bioturbated limestones, while in the supra tidal environments beach and bar facies are interbedded with algal mat deposits.

Tectonic History

Lower Paleozoic

In the lower Paleozoic, the Permian Basin region was home to a passive continental margin following the breakup of Laurentia. Slow subsidence formed the Tobosa Basin. This continued until the upper Mississippian.

Ouachita-Marathon Orogeny

Towards the end of the Mississippian, the Hercynian Orogeny formed the Oauchita-Marathon thrust belt and deformed the Tobosa Basin into two foreland basins (Delaware and Midland basins). These basins were separated by a structural high, the Central Basin Platform. Uplift of areas surrounding the new basins provided provenance for large volumes of siliciclastic sediment to be deposited in both the Midland and Delaware basins through the Pennsylvanian.

Permian Basin Stage

Through the Permian, stable tectonic conditions combined with subsidence of the Delaware and Midland basins allowed for the fill of these basins with nearly four kilometers of sediment. It is these thick accumulations that produce many of the hydrocarbons of the region, and give the basin its name.

Unconventionals

The Permian Basin accounts for a large percentage of U.S. crude oil production. Both this percentage and the total crude oil production from the Permian Basin are expected to increase significantly by 2020. Image from the U.S. Energy Information Administration.

The Permian Basin has experienced huge growth since 2012 and the implementation of large scale horizontal drilling and Hydraulic fracturing. This has greatly increased production in the region, pushing the Permian Basin to account for more than forty percent of United States oil production. Figure 1 displays a graph of this production increase alongside several other prominent North American basins. According to IHS Markit, production in the Permian is projected to grow to 5.4 million barrels per day by 2023, with nearly 41,000 new wells coming online between 2018 and 2023.5. The primary Unconventional reservoir plays are Shale, carbonate, and tight sand intervals in the Wolfcamp, Bone Spring, and Spraberry Formations.

Important Papers

This section allows contributors to point to other important papers or books that have been written on the subject matter. 

External links

• Basin Geology, SEPM Strata: http://www.sepmstrata.org/page.aspx?pageid=136
• Permian Basin, North America: https://en.wikipedia.org/wiki/Permian_Basin_(North_America)
• Completion Trends, DrillingInfo.com: https://info.drillinginfo.com/completion-trends-proppant-and-fluid-concentrations-on-the-upswing-across-all-basins/
• Permian Basin Key Facts and Figures, Oil Industry Insight: https://oilindustryinsight.com/oil-gas/petroknowledge/permian-basin-key-facts/
• U.S. Energy Information Administration: https://www.eia.gov/todayinenergy/detail.php?id=30952