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EOR (Enhanced Oil Recovery)


Enhanced Oil Recovery (EOR) is a technology to increase the recovery factor of crude oil. This technology is applied to formations with low recovery factor using normal production methods, and production wells with low production efficiency caused by the passage of years since the start of production.

JAPEX has been working on the development of a variety of EOR technologies.

What is Enhanced Oil Recovery (EOR)

Crude oil flows out from wells drilled into the formation (reservoir) where the existence of the oil is confirmed, caused by the energy (pressure) of the reservoir. However, the amount of crude oil that can be recovered by the energy of the reservoir alone is said to be less than 30% of the total amount of crude oil in the ground. Accordingly, technology to increase the recovery factor of existing oil fields is as important as the discovery of new oil fields, and various technologies are being applied and studied.

In general, the development of oil and gas field is classified into the following three phases:

  • Primary recovery: Crude oil flows out caused by the energy of the reservoir.
  • Secondary recovery: Water or gas is injected into the reservoir to push out the crude oil, or pumped out crude oil mechanically by a pump installed in the well.
  • Tertiary recovery: The physical and chemical properties of rocks and formation fluids are altered to recover the crude oil remaining underground.

The recovery factor at the primary recovery is generally said to be no more than 30% of the total amount of crude oil in the ground. Although secondary recovery increases the recovery factor to about 40%, there is still 60% to 70% of the crude oil left underground. To further increase the recovery factor, the tertiary recovery, called Enhanced Oil Recovery (EOR) is used. Many research institutes and oil development companies have been developing technologies to change the physical and chemical properties of rocks and formation fluids and to recover the crude oil remaining in the ground.


Production phase and production volume trends at a typical oil and gas field

JAPEX Initiatives

JAPEX has the proven track records applying various EOR technologies at some crude oil and other production operation sites in Japan and abroad.

  • Some oil fields in Japan: Gas injection and Water Alternating Gas (WAG) method
  • Oil Sands Development in Canada: Steam-Assisted Gravity Drainage (SAGD) method,

Also, JAPEX has a number of key technologies that are important factors for EOR studies.

  • Various analyses of rock, gas, and oil, which are important in the EOR study phase
  • Tests to determine flow conditions and recovery factor under simulated underground conditions (core flood tests)
  • Reservoir simulation to study effective EOR methods

Application of the Gas Injection Method to the Iwafune-oki Oil and Gas Field

The Iwafune-oki oil and gas field (*) in Niigata Prefecture is the first offshore oil and gas field in Japan where the Gas-based EOR has been fully applied.

JAPEX Offshore, Ltd. (JPO), one of our subsidiaries, applied the gas injection method, a type of EOR, to the Iwafune-oki oil and gas field (*) in January 2006, for the first time on a commercial scale for an offshore oil field in Japan.

In 2002, we began to study the application of EOR as a countermeasure against the decline in crude oil production and conducted a pilot test in December 2004 in our main reservoir (2,100 m layer) based on the conclusion that the method of injecting gas into the top of the reservoir structure (the gas injection method) is effective. Given the positive results of the pilot test, we started the gas injection method on a commercial scale in January 2006. The implementation of the method until December 2017 has improved the crude oil recovery factor of the relevant reservoirs and extended the production period by more than 10 years from the original assumption of expected profitability termination.

In addition, to further increase the amount of crude oil recovered, we have applied the Water Alternate Gas Injection (WAG) method to the same layer since January 2018.


Effects of increasing crude oil production by implementing the gas injection method in the 2,100 m layer of the Iwafune-oki oil and gas field


The development and production operation of the Iwafune-oki oil and gas field is a joint project of Japan Petroleum Exploration Co., Ltd., JAPEX Offshore, Ltd., and Mitsubishi Gas Chemical Company, Inc.


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