Investigation of Hydrocarbon & Non-hydrocarbon (CO2, N2) Gas Injection on Enhanced Oil Recovery in One of the Iranian Oil Fields

Masjed-I-Suleyman (MIS) field is the first field in the Middle East that has produced oil and has such a long production history (100 years). This field’s production started in 1911. Most of the oil production in the Middle East comes from carbonate reservoirs, the majority of which are fractures. These reservoirs tend to produce at high rates in their early production period followed by low rates later on, leading to low overall recovery. The early production rate of this field was 120000 stb/day, now reaching about 2000 stb/day. MIS field has produced 1.39 billion stb of oil as of January 1, 2010, which makes it a giant field by world standards. 267 million of this produced oil was re-injected into the reservoir and if the recycled oil re-injected into the reservoir is included, the net total oil produced as of January 1, 2010 would be 1.123 billion stb. Based on original oil-in-place of 6 billion stb, the recovery factor equates to 23.2% (based on the gross oil production) or 18.7% (based on the net oil production). So this reservoir is a candidate for an EOR process. It seems the gas injection into oil reservoirs is one of the most effective methods in EOR approaches. In this study, the injection technique that was used includes gas injection with different fluids that causes an immiscible process. A compositional reservoir simulator has been used to determine the effect of the gas injection process on reservoir production to optimize the oil recovery for the MIS field. Simulation results show that gas injection isn’t useful for this field.