Saudi Aramco solves field pressure mystery
Although Harmaliyah oil field had been dormant since 1998, the reservoir's pressure had been steadily rising,
alarming engineers. This pressure (averaging 360 psi higher than other area wells) threatened to cause unintended oil
migration into inaccessible nooks and crannies of nearby reservoirs -- an event that could damage nearby reservoirs
(Arab C/Hanifa) and render large volumes of petroleum forever irretrievable.
Generally, water injected into fields maintains pressure, but Harmaliyah has no water-injection system, so the rise in pressure was a mystery.
Reservoir management engineers determined that the pressure rise was being indirectly caused by water-injection operations at the nearby Hawiyah and Haradh fields in the Southern Area. (As it turns out, Harmaliyah shares the same subterranean aquifer with those fields.) The challenge was figuring out a way to relieve Harmaliyah pressure in the safest, most cost-effective way.
When Harmaliyah was a producing field, its oil was fed through its own Harmaliyah Gas-Oil Separation Plant (GOSP),
but that facility was mothballed in 1998. To reactivate the GOSP would be very expensive. South Ghawar production
experts, after extensive brainstorming and in consultation with other specialists, came up with the solution: Free
Harmaliyah's pressure was sufficient for its crude to be "free flowed" to the operational 'Uthmaniyah GOSP-4, about 57 km from the dormant Harmaliyah GOSP. The Free Flow Project was initiated in 2001, and free-flow of crude started this year. Thus, officials were able to ease the pressure on Harmaliyah without re-starting its GOSP -- which means substantial savings in annual operations, maintenance and inspection of the plant.
The free-flow idea will produce revenues from new production that reached 55,000 bpd earlier this year. The project
execution was achieved by using "in-house resources," including the essential expertise of young Saudi
Harmaliyah field was discovered in January 1972 and put into production in August 1973. The field was mothballed and put back into production three times, most recently in 1998.