PDO enhancing oil production, expanding gas operations
The year 2003 was good for gas-condensate reserves bookings but not much for black oil additions, said Petroleum Development Oman.
PDO booked 830 bcf of gas and 86.2 million bbl of condensate based on discovery of Fakhr field and extension of Burhaan West field. It added 35.4 million bbl of oil reserves, all from near-field exploration.
OGJ estimated Oman's yearend 2003 proved reserves at 5.5 billion bbl of oil and 29.3 tcf of gas.
The company drilled 10 oil and 4 gas exploration wells in 2003, not all of which resulted in commercial discoveries. The discovery wells "provided data showing significant scope for additional reserve bookings," PDO said.
Exploration in 2003 yielded a 42% commercial success rate and finding costs of 52¢/boe.
PDO averaged 702,000 b/d of oil production in 2003, near its goal of 703,000 b/d. Condensate production averaged 59,000 b/d.
Outlays in 2003 totaled $1.124 billion in capital spending and $502 million on operations. Members of PDO are the Omani government 60% and affiliates of Royal Dutch/Shell Group 34%, Total SA 4%, and Partex (Oman) Corp. 2%.
Sustaining production
PDO embarked in 2003 on programs for the large-scale expansion of waterflooding to improve short and medium-term production and enhanced oil recovery for longer-term gains.
It completed studies for waterflooding projects at 10 field clusters. Three—at Fahud, Marmul, and Lekhwair—progressed to approval by the Decision Review Board. It identified for later waterflooding a fourth project made up of several fields in the Rahab-Thuleilat-Qaharir (RTQ) cluster.
PDO established well and reservoir management teams in the 23 field RTQ cluster and at Marmul in the South directorate and in all field clusters in the North directorate. The teams focused on data gathering, optimizing production, working over wells, and maintaining and repairing equipment.
Plans call for first EOR oil from Mukhaizna field in 2007 in a project that will require the drilling of 1,800-2,200 new wells. Front-end engineering and design for EOR at Harweel began in 2003, and a Qarn Alam EOR project is to be developed from results of a steam injection pilot that began last year.
On the gas side, three heavy rigs were added to the fleet of four designated for drilling gas wells.
Addition of a compressor hiked capacity of the government gas plant at Yibal to 23 million cu m/day. Early construction began on the Saih Nihayda gas plant, and pipe was ordered for a 48-in. loop from the plant to near Al Kamil.
Deep, sour production
Meanwhile, PDO started production in March from Zalzala field, one of the Harweel cluster of fields in southern Oman 80 km southwest of Marmul.
Zalzala is one of a string of discoveries made during 1997-2002 due to improvements in seismic imaging that revealed carbonate reservoirs below a thick salt layer.
PDO's deepest producing field at nearly 5,000 m, high-pressure Zalzala is the company's first multiwell field to begin production in the past 4 years. It was discovered in 2001, and its Cambrian age reservoir is among the world's oldest (OGJ, July 5, 1999, p. 38).
PDO transports Zalzala oil and gas through a single, 70 km, 12-in. pipeline to the Birba production station. This is the company's longest such pipeline. Gas content is 5% hydrogen sulfide. Oil is exported, and gas is injected into Birba field.
Also scheduled for start-up were Ghafeer, Sakhiya, and Dafaq fields, which were to bring production from the cluster to 18,000 b/d of oil and 30 MMcfd of gas by yearend.
Second phase development calls for a miscible gas injection EOR project in which Harweel gas, instead of being piped to Birba, will be reinjected into fields in the cluster, boosting production and adding reserves, PDO said.
