KIRKUK: The Phoenix in The Middle East

A Brief History of Iraq and its Geography

The Kirkuk oilfield, discovered in 1927 and historically known as Mesopotamia, a Greek word meaning "the land between two rivers" of the Euphrates and Tigris in today's Iraq have a record of oil and bitumen dating back to the earliest human civilization, more than five thousand years ago.

Iraqi geology is closely related to the Zagros orogenic belt in southwest Iran. These Cenozoic mountains formed as two continental plates, Arabia and Asia, collided, closing the Tethys Sea that once lay between them. The highly deformed overthrust section of Zagros is present only in the northeastern Kurdistan region of Iraq.

Oil and Bitumen Seeps in Iraq

Oil seeps garnered the attention of 19th-century explorers and geologists who mapped the structure and stratigraphy of the Zargos mountains and foothills.

Mesopotamia's history has an abundance of bitumen seeps, used as waterproof mortar in the brick walls of temples and road pavements in Middle Eastern cities. A merchant in the 16th century called Cesare Frederici visited the town of Hit and noted some holes that continually smoked and expected an amount of pitch, which the Arabs believed to be "the mouth of hell" in Hit.

History and Geopolitics of the Kirkuk Oilfield

The oilfield is separated within the Kurdistan region of Iraq's Erbil Governorate and the northern Kirkuk Governorate. The Turkish Petroleum Company constructed the Kirkuk oilfield at Baba Gurgur in 1927, and the Iraq Petroleum Company (IPC) eventually put it into production in 1934 before nationalization in 1972.?

The Kirkuk Oilfield was developed by the North Oil Company (NOC), a state-owned business after the Iraqi National Oil Company (INOC) ceased operating the field in 1989. July 11, 2014, Kurdistan Regional Government (KRG) forces took over the oilfield. Since then, 120 Mbopd have been exported from Kirkuk and the adjoining Bai Hassan field through the KRG export pipeline to the Turkish port of Ceyhan.

The Oilfield Reservoir Geology

There are three pay zones in Kirkuk. The first is the Kirkuk Tertiary Reservoir, the most productive reservoir with 98% of recoverable reserves. The Upper and Middle-Cretaceous for the second and third deposits are insignificant and non-producing. There were over 8.9 Bbo of proven remaining oil reserves in 2007 out of the initial 38 Bbo of projected oil-in-place reserves.

At the original oil-water contact level in the Tertiary Reservoir, the oilfield is an anticlinal structure, trending northwest to southeast, measuring 100 km long and 4 km broad. From southeast to northwest, the field's three domes—Baba, Avanah, and Khurmala—are divided by saddles named Amshe and, Dibega.

The 365m (1,200ft) thick Eocene-Oligocene Kirkuk Tertiary Reservoir formed from many fractured limestones, some porcelaneous and some dolomitized. These limestones have a variety of porosity and permeability qualities deposited within varying habitats, including back-reef/lagoonal, fore-reef, and basinal.

The oil contains a low-permeability, high-capacity matrix-pore system having a large, extremely permeable, but low-capacity fracture system. The carbonates of the Kirkuk Group have excellent porosity and permeability; some wells in the Baba dome produced 100,000 bopd. The porosity ranges from 15 to 25% (on average, about 22%), and the permeability is generally around 100 mD. Oil's API gravity ranged from 18 to 36 degrees (on average around 30 degrees), and at the reservoir's initial pressure of 1,100 psi, it was approximately 500 psi undersaturated. It contains 1.5–4% sulfur.

Production Statistics and Emerging Problems

The estimated oil-in-place reserves for the oilfield original as of January 1989 were 38,045 MMbo, the proven remaining oil reserves were 10,238 MMbo, and the total oil production through 1988 was 12,017 MMbo. 8,973 MMbo of proven reported oil reserves exist as of January 2007, including an estimated 2,800 MMbo of recoverable for Khurmala Dome.

Production of Kirkuk began in 1934 from the Tertiary Reservoir in the Baba and Avanah Dome and continued slowly for the first 20 years. Production increased three times as quickly in just three years, starting in 1951. The density of fractures throughout the entire structure, especially in the structurally higher zones, is known as the reservoir characteristics. Since the water drive force is weak due to the rapid rise in the oil/water contact, the rapid decline in reservoir pressure caused the development of secondary gas caps in both; Baba and Avanah Dome.

Water Drive Performance and Solutions of the Fractured Field

During the production under natural depletion, thirteen oil-water interactions counted since gas caps anticipated to develop further down the structure than the oil and water contacts would push them up. The oil-producing wells drilled relatively low on the oilfield structure.

A quick and easy way to calculate recovery and reserves is to define recovery as the total volume of rock inundated, then extrapolate the recovery curve to that whole volume.

Rate of water injection (or ingress from an aquifer) and the fracture volume ratio of the submerged rock factors affecting recovery from fractures. The rate of water injection, the rate of gravity drainage, and the rate of imbibition in the already submerged rock all affect recovery from the matrix.

Since modern porosity tools were not available when logging programs were conducted, presenting uncertainties about the connate water location, the estimations of oil-in-place for the matrix rocks are based on conventional core analysis therefore subjected to some degree of uncertainty.

The total dissolved solids content of the water in a sampled fractured system fluctuates along the field, with values between 30,000 and 100,000 ppm. This explanation might be that the rock varied little between different locations.

Can Kirkuk Oilfield rise from the ash embers currently burn like a phoenix rebirth? This field has great potential to use enhanced oil recovery to supply the current energy needs of today's Mesopotamian descendants.

References

Mrs. F. M. Al-Naqib, R. M.-D.-I. (1971). Water Drive Performance of the Fractured Kirkuk Field in Northern Iraq. Society of Petroleum Engineers of AIME. Dallas, TEXAS: American Institute of Mining, Metallurgical, and Petroleum Engineers Inc.

Munim Al-Rawi, P. (2023). Kirkuk. A Silent Giant Oilfield. Retrieved from GeoExPro: https://geoexpro.com/kirkuk-a-silent-giant-oilfield/

Rasoul Sorkhabi, P. (2009, April 2). Oil from Babylon to Iraq. Retrieved from GeoExPro: https://geoexpro.com/oil-from-babylon-to-iraq/