North louisiana salt basin

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History of the Basin

Fig. 1 Location of North Louisiana Salt Basin

[1]The North Louisiana Salt Basin is located in the north west corner of Louisiana and is directly linked to the evolution of the Gulf of Mexico and this can be seen in fig. 1. Created by early rifting paired with wrench faulting, the North Louisiana Salt Basin is bounded with Sabine Uplift on the west, on the east by the Monroe Uplift and LaSalle Arch, and on the south by the Angelina Flexure. [2]This basin is home to the Haynesville shale which covers around 9000 square miles and has a thickness of 200 to 300 feet. This shale play has the ability to become a significant resource for the United States. Fig. 2 shows where the Haynesville shale play area sits in reference to the North Louisiana Salt Basin.

Primary Geologic Risks

Fig. 2 Location of Haynesville Shale

[2]The Haynesville shale lies within the North Louisiana Salt Basin with depths up to 13,500 feet, high bottom hole temperatures, and consistently high-pressure rates. The production of gas at the beginning was non-stop and it requires the treating of carbon dioxide removal which can be deadly if not managed properly. The shale has distinctive features that created hostile conditions. This requires almost double the amount of hydraulic horsepower, more advanced fluid chemistry, and higher treating pressures. The high-temperature ranges that the shale sits in creates more problems. You must have high temperature/high-pressure equipment in order to log and you must watch your water conservation/disposal in these deep wells.

Petroleum Elements

Source Rock & Reservoir

[3]Like most shale plays that have been successful, the Haynesville Shale is considered both a source rock and a reservoir rock. It can be considered a source rock due to its high organic content and a reservoir rock due to its ability to store and transmit hydrocarbons. The hydrocarbons are stored and moved around due to adequate porosity and permeability.

Fig. 3 Salt Dome

Traps and Seals

[4]In the North Louisiana Salt Basin, the trap is considered a structural trap but more specifically a salt dome. A salt dome is a column of salt that has intruded upwards into the overlying sediments. Most of the time, salt domes cause deformations in the rocks and form traps that will hold oil and natural gas. As seen in fig. 3, this is how a salt dome drives up and begins to bend rocks to the point that they can form a trap. This bending ultimately causes an anticline seal in the shale.

Migration

[5]1-D and 2-D models were created across the North Louisiana Salt Basin to measure fluid flows through the Haynesville Shale.  Lower permeability paired with hydrocarbon generation resulted in high pore pressures. Due to up dip fluid migration, there have been abnormal high fluid pressures along with natural fractures aiding in horizontal fluid migration throughout the shale.

Future Petroleum Potential

[1]When comparing the North Louisiana Salt Basin to other Salt Basin’s in the area, there is potential for undiscovered and undeveloped reservoirs. Looking at Upper Jurassic units in the Mississippi Interior Salt Basin, they account for 20% of current oil production and 38% of current gas production. The depositional features of the North Louisiana Salt Basin are very similar but are only account for about 10% of current oil and gas production. [6]With Texas and Louisiana being for oil and gas, experts believe there is anywhere from 35,000 to 50,000 wells left to be drilled in this area. The future looks bright considering other similar basins as well as the potential to find more.

Engineering Aspects

[6]The Bossier shale sits atop the Haynesville shale and the sweet spot is considered to be on the Louisiana side. The over-pressure in the Haynesville shale initially created high production rates and low lifting costs. It mainly produces dry gas. Dry gas does not need to be processed before being liquified and there is plenty of facilities/pipelines, so infrastructure is rarely an issue.

Further Reading

Haynesville Shale's Role in Natural Gas Demand

Haynesville vs Bossier Shale

Salt Domes are Important to Louisiana

References

  1. 1.0 1.1 Mancini, Ernest. (2012). Basin Analysis and Petroleum System Characterization and Modeling, Interior Salt Basins, Central and Eastern Gulf of Mexico. Search and Discovery. Retrieved April 5, 2021, from http://www.searchanddiscovery.com/documents/2012/10396mancini/mancini-part3.pdf
  2. 2.0 2.1 Speight, James (2020). Haynesville Shale. ScienceDirect. https://www.sciencedirect.com/topics/engineering/haynesville-shale.
  3. Haynesville Shale Louisiana. (2020). MineralWise. Retrieved April 5, 2021, from https://mineralwise.com/directory/shale-plays/haynesville-shale-louisiana
  4. What is a Salt Dome? (2021). Geology.com. Retrieved April 5, 2021, from https://geology.com/stories/13/salt-domes/
  5. Torsch, William. (2012). Thermal and Pore Pressure History of the Haynesville Shale in North Louisiana. LSU Digital Commons. Retrieved April 5, 2021, from https://digitalcommons.lsu.edu/gradschool_theses/268/
  6. 6.0 6.1 Background Information About the Haynesville Shale. (2021). Natural Gas Intelligence. Retrieved April 5, 2021, from https://www.naturalgasintel.com/information-about-the-      haynesville-shale/