SPE: Saudi Aramco aims at sustained deliverability

Contrary to recent speculation about an imminent sharp decline in Saudi Arabian oil production capacity, Nasen G. Saleri, manager-reservoir management of Saudi Aramco, told participants at the Society of Petroleum Engineers Annual Technical Conference and Exhibition in Houston that Saudi Aramco is pursuing a strategy of maintaining low depletion rates in its fields of 1-3%/ year for at least 20-25 years.

He added that even the recent increase in production to 10 million b/d from 8.5 million b/d in a 48-hr period was within Saudi Aramco's strict tenets of not producing a field at production drawdowns that could damage a reservoir.

Saleri said that Saudi Aramco's current producing capacity is 10 million b/d but that production is now about 9.8 million b/d because the company cannot find buyers for some of its heavier crude at a price it was willing to accept. He added that the company is reviewing the possibility of increasing producing capacity to 11-12 million b/d in the near term, and eventually to 15 million b/d.

Saudi reserves

Saleri explained that Saudi Aramco's initial resource base was 700 billion bbl and that in April cumulative production had reached 100 billion bbl. He categorized the remaining oil resource base as 260 billion bbl proved, 32 billion bbl probable, 71 billion bbl possible, and 238 billion bbl contingent.

He said reserves have changed over time. As an illustration, he indicated that production from one of the mature reservoirs in Ghawar field had already exceeded by 23% the recoverable reserves calculated in 1973, and the reservoir was still producing at more than 2 million b/d. Saleri said the water cut in Ghawar has decreased during the last 5 years while oil production has increased. In 1998 the water cut was 36.5%, while in 2003 it had decreased to 33%, he said.

Saleri explained that currently Saudi Aramco uses a 60% recovery factor for fields under waterflood. He said that this value is conservative because data indicate that oil saturation in swept zones is in the order of 21%. This would point to potential oil recoveries of 76.3-78.6%, according to Saleri.

Technologies

Saleri said various technologies have allowed Saudi Aramco to better monitor and develop its resources. He said the company monitors and reviews 25 key parameters in each of its reservoirs. This has allowed Saudi Aramco to decrease its unit cost significantly. For instance in the Kuff gas development, Saleri said, the unit cost in 2003-04 was only 41% of that in 1998-2000.

Real-time geosteering is another technology that Saleri said is changing development schemes. As an example, Saudi will use quad-laterals drilled with geosteering to produce the Harad Increment III development in the south of Ghawar field.

Saleri said this development will go on stream in July 2006, producing at a 30-year plateau rate of about 300,000 bo/d. Saleri emphasized that strict regulation of the production drawdown will limit reservoir depletion rates to about 1.7%/year.