There are two phases involved with the extraction of oil from reservoirs that are employed as the extraction develops. Primary recovery leads to a natural depletion of the reservoir. In order to aid oil, recovery water is pumped to sweep oil and also to maintain reservoir pressure, this is the ‘second recovery’ phase of the operation. If water injection fails to recover all the oil reserves ‘tertiary recovery’ techniques are employed to harvest the remaining deposits.
We have successfully implemented EOR extract using hydrocarbon miscible gas, the team is currently working towards employing new EOR technology, such as low salinity.
EOR development is not without its technical drilling challenges. There are considerations concerning our existing infrastructure, with certain facilities requiring significant upgrades. However, the development of EOR capabilities will help prolong the shelf life of the company.
EOR using hydrocarbon miscible gas is an interesting technical development as the gas associated with oil production can be re-injected.
Our Mishrif reservoir is the ideal depth to apply effective hydrocarbon miscible gas injection. In addition, the size of the reservoir combined with the quality of the rock allows extensive oil recovery. The oil quality – light – ensures miscibility with the associated gas. Based on the favourable vertical and horizontal conditions we ran numerous tests throughout the 1990’s. The successful horizontal pilot proved to be a technical success, yielding positive economic results.
As technology evolves we are constantly monitoring the optimum method to employ EOR in our offshore assets.
Low salinity water (EOR LSW) highlights the effect salt water has on oil recovery. Replacing sea water injection with low saline water increases the recovery of oil. This is a relatively new concept but one that is nearing maturity in terms of R&D and testing, we are starting to see the global implementation of this extraction technique.
Using water involves much lower capital investment and operating costs, leading to a more favourable financial outcome compared to other EOR methods. In fact, LSW is considered the cheapest EOR method available.
We have conducted a number of studies, and have found that our reservoirs fit the criteria for effective EOR LSW recovery. A pilot is underway prior to field implementation.