2016 Volume 81 Issue 6 Pages 441-446
Iwafune-Oki field is the unique offshore field currently under operation in Japan. It was discovered in 1983 and has been producing from several oil and gas reservoirs since 1990.
Because the decline of oil production had been confirmed after plateau period, we started to examine IOR application to Zone 2100 m, which was main reservoir of this field. This study indicated that natural gas IOR, using the abundant gas contained in the other zone, was effective.
The pilot injection test was started in December 2004. The transition from the test to regular operation was decided in 2006 with confirming the increment of production oil.
We have continued the production operation with the success of this IOR, though our prediction suggested that we couldn't continue the production after 2009 without the IOR. By the end of 2015, the oil recovery ratio of Zone 2100 m was 4% higher than without the IOR. In addition, the profit limit of Iwafune-oki field was extended.
