Mesopotamian Foredeep Basin

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Introduction

Photo 1: Structural Map of the Mesopotamian Foredeep Basin (2010)[1]

The Mesopotamian Foredeep Basin is a flat Iraqi territory, which has been historically referred to as the area of land between the Tigris River and the Euphrates River. The basin has a slight slope from the northwest region, around Ramadi and Tkrit, toward the Arabian Gulf which is in the southwest region. Additionally, The Mesopotamian Foredeep lies between Zagros Orogenic Belt, which extends from Buzurgan to Sinjar, and the stable interior of the Arabian Platform, which is bounded by the Anah Fault System and the Abu Jir Fault Systems (Reference Photo 1)[2]. Large sums of oil produced domestically in Iraq have been discovered to be sourced in the Jurassic rocks and in the Cretaceous and Tertiary reservoirs in the Mesopotamian Foredeep Basin. Being one of the three major petroleum systems in Iraq, the Mesopotamian Foredeep Basin has allowed for Iraq to become a major petroleum-producing country in the Middle East.

History

Interest in the Mesopotamian Foredeep Basin grew largely in the late 90's and early 21st century. Before this time, it was very difficult to assess the petroleum resources in the Mesopotamian Foredeep Basin, as well as adjacent basins like the Zargos fold belt, because data regarding potential source rocks or prospective reservoirs had never been explored. In 1983 the American Association of Petroleum Geologist performed a study over a series of scattered wells in Southern Iraq, in particular the Mesopotamian Basin. This group of petroleum geologist was interested in burial temperature history data, these initial studies performed in the 1980's led to to a spike in interest in the region.[3]

During the late 90's and early 21st century, several studies of petroleum geoscience were preformed In Iraq. These studies included topics such as: stratigraphy, sedimentology, seismic mapping, and general basin modeling (Reference Photo 2 &3). All of these studies led to an increased scope of valuable insights into timing of petroleum generation and migration within the Mesopotamian Foredeep Basin (Reference Photo 3). The events which proceeded this led to a huge boom in the production rates in Iraq.

Geologic Setting and Risks

The Mesopotamian Foredeep Basin is a huge part of the Zargos Fold. The Mesopotamian Foredeep Basin has a wedge shaped profile, the basin of Mesopotamia is considered the continental terrain of the Zargos foreland, whereas the Arabian Gulf Basin represents marine terrain. Throughout the 80’s and the 90’s there was a large interest in comprehending the tectonic division of Iraq, and in specific how they correlated with the petroleum systems. The earliest studies and data was published by Buday (1980), he is credited with the division of the stable and unstable zones (Reference Photo 1). As the popularity of petroleum systems in Iraq grew, more and more tectonic divisions were noted and the data began to get more technical.

Historically, the “Mesopotamian Flood Plain” was often considered the entirety of the basin, but thanks to the help of technological advances we now know that the Mesopotamian Foredeep Basin is much larger than what was once interpreted. In fact, the present day basin of Mesopotamia extends from northeast Syria to the Straits of Hormuz. In its entirety, the basin consists of two domains, the first covers parts of northeast Syria, Iraq, and parts of Kuwait and the coastal plains of Iran, and the second is a marine, represented by the Arabian Gulf Basin.[4]

Photo 2: Megaseismic Line showing the Inner (Stable) Arabian Platform, Mesopotamia Foredeep and Zagros Mountain Front.[5]
Photo 4: Stratigraphic section and major tectonostratigraphic phases relevant to the Paleozoic, Jurassic, and Cretaceous-Tertiary Total Petroleum Systems of Iraq.[6]

Petroleum Elements

Photo 3: Map showing location of Mesopotamian Basin and Zagros fold belt, and major oil and gas fields in these regions[7]

The optimal environment for hydrocarbon generation and accumulation in the Mesopotamian Foredeep Basin includes depths in these geologic ages: Jurassic, Cretaceous, and Tertiary. The Sargelu Formation and the Naokelekan Formation are two formations that make up the upper half of the Jurassic geologic age, rocks in these formation make very good source rock and generate the majority of the oil in the Mesopotamian Foredeep Basin (Reference Photo 4).[8]

The Sargelu Formation ranges in thickness depending on the region it is in, but in the southern region of Iraq it can range from 100m-400m in thickness. The Sargelu Formation consists of argillaceous and bituminous limestone and calcareous shale and has a high concentration of source rock in the lower 40m of its lithology.[9]

Traps

While most oil generated in the basin derives from the Jurassic time period, the Cretaceous and Tertiary rocks in the Mesopotamian Foredeep Basin serve a very important trapping purpose. Cretaceous reservoirs account for trapping around 76% of the petroleum resources, and do so at depths greater than 3 km below the surface.[10]

Petroleum exploration, in the southern region of the basin, is heavily influenced by structural and stratigraphic traps. To be more precise, these are large trapping anticline structures with N-S striking, these anticlines present themselves in the Paleozoic and Mesozoic time periods.[11]

Future Petroleum Potential

The majority of known petroleum generation in the Mesopotamian Foredeep Basin can be found within Jurassic source rocks, lack of post-collision metamorphic or intense tectonic activities, and adequate placement of source and cap rocks, created ideal conditions for hydrocarbon accumulation which migrated into hydro-carbon carrier beds positioned in the late Paleocene geologic period. With that being said, Iraq, as of 2004, had a total proven reserves of 113 billion barrels of oil and 110 Trillion cubic feet of Gas. Moreover, the Iraqi's estimate that there is roughly 14 billion to 85 billion total undiscovered barrels of oil still in the known formations.[12]

Although, it is likely that other formations below the Jurassic obtain a pursuable percentage of total organic carbon, zones below the Jurassic are associated with large downhole risks which have discouraged the exploration and extraction of hydro-carbon's at these particular depths. Disequilibrium compaction of strata in the Mesopotamian Foredeep Basin, developed by clay dehydration, has led to overpressures in the basin which make it incredibly difficult to operate in these zones.

Petroleum Engineering and Facility Engineering

Photo 5: 3-D model simulation showing oil-flow vectors and oil accumulations for the petroleum drainage areas within the Mesopotamian Foredeep Basin.[12]

During the time of high interest in the Mesopotamian Foredeep Basin, there was a increase in demand for data regarding vertical depth below the surface. This led to a series of studies performed by groups of geologist, engineers and petroleum physicist who used a multitude of data collection tools to assimilate reports of information. For example, a regional, one-dimensional, two-dimensional, and three-dimensional, petroleum-system model of the Mesopotamian Foredeep Basin was developed using an Integrated Exploration System software called Petromod. The Petromod is a basin simulator which provides insights on thermal histories, source rock maturity, generation and migration of hydro-carbons, and flow directions of fluids (Reference Photo 3).[13]

The development of reliable data on the Mesopotamian Foredeep Basin led to a boom in production and completion projects which can be seen by the presence of many large companies accruing interest in the region, such as: Eni, Kogas, Mayasan Oil Company, South Oil Company, and Occidental. In order to optimize gains from production, companies ventured in facility engineering projects that would allow them to optimize profits and efficiency of production. One recent example of this occurred in February of 2019, when Basrah Gas Company announced a 40% increase in storage facilities.[14] This announcement came with a projection of 400 mmcfpd of newly captured natural gas which would be accumulated from oil fields within the Mesopotamian Basin, as well as oilfields adjacent.[14]

References

  1. Fouad, S.F.A., and Nasir, W.A.A., 2009. Tectonic and structural evolution of Al-Jazira area. Geology of Al-Jazira Area, Iraqi bulletin of geology and Mining, special Issue No. 3: 33 – 48
  2. Fouad, S.F.A., and Nasir, W.A.A., 2009. Tectonic and structural evolution of Al-Jazira area. Geology of Al-Jazira Area, Iraqi bulletin of geology and Mining, special Issue No. 3: 33 – 48.
  3. Ibrahim, M.W., 1983. Petroleum geology of southern Iraq. American Association of Petroleum Geologists Bulletin: v. 67, p. 97-130
  4. Fouad, S. F. (2010). TECTONIC AND STRUCTURAL EVOLUTION OF THE MESOPOTAMIA FOREDEEP, IRAQ. Iraqi Bulletin of Geology and Mining, 6(2).
  5. Fouad, S. F. (2010). TECTONIC AND STRUCTURAL EVOLUTION OF THE MESOPOTAMIA FOREDEEP, IRAQ. Iraqi Bulletin of Geology and Mining, 6(2).
  6. Verma, M.K., T.S. Ahlbrandt, and M. Al Gailani, 2004. Petroleum reserves and undiscovered resources in the Total Petroleum Systems of Iraq: Reserve growth and production implications. GeoArabia: v. 9, No. 3, p. 51-74.
  7. Ahlbrandt, T.S., R.M. Pollastro, T.R. Klett, C.J. Schenk, S.J. Lindquist, and J.E. Fox, 2000. Region 2 Assessment Summary—Middle East and North Africa. In USGS World Petroleum Assessment 2000—Description and Results, Chapter R2: DDS-60, 46 p.
  8. Alsharhan, A.S. and A.E.M. Nairn, 1997. Sedimentary basins and petroleum geology of the Middle East. Elsevier, The Netherlands, 843 p.
  9. Sadooni, F.N., 1997. Stratigraphy and petroleum prospects of Upper Jurassic carbonates in Iraq. Petroleum Geoscience: v. 3, p. 233-243.
  10. Al Gailani, M., 2003. Assessing Iraq’s oil potential. Geotimes: v. 48, p. 16-20.
  11. Petroleum generation and migration in the Mesopotamian Basin and Zagros fold belt of Iraq: Results from a basin-modeling study. (2004). GeoArabia, 9(4), 41-72.
  12. 12.0 12.1 Janet K. Pitman, Douglas Steinshouer, Michael D. Lewan; Petroleum generation and migration in the Mesopotamian Basin and Zagros Fold Belt of Iraq: results from a basin-modeling study. GeoArabia 2004;; 9 (4): 41–72. doi:
  13. IES Integrated Exploration Systems, 2004. PetroMod, 1D/PetroCharge Express, and PetroRisk Software. IES, Bastionstrasse 11-19, 52428 Juelich, Germany, (www.ies.de).
  14. 14.0 14.1 Editor. (2019, February 12). Basrah gas company to increase capacity BY 40%: IRAQ business news. Retrieved May 12, 2021, from https://www.iraq-businessnews.com/2019/02/13/basrah-gas-company-to-increase-capacity-by-40/

External Links

  1. https://www.eia.gov/international/analysis/country/IRQ
  2. https://www.opec.org/opec_web/en/about_us/164.htm
  3. https://iogsiraq.com/