Oman - Solar Base.
The history of oil production in Oman is unique. There had been a steady increase in oil production until the turn of this millennium, reflecting Oman's complex geology. Technology has evolved and enabled a steady increase in recovery, up to 20% in some fields. Yet the easy oil has all been found and developed. Now what is left is the difficult oil province. But Shell Development Oman remains optimistic about the future in this country. The relationship with the state is one of maximum knowledge exchange. In 2006 Shell Technology Oman's R&D centre in Muscat began working closely with Sultan Qaboos University's Oil & Gas Research Department and PDO.
Oman geology for petroleum reflects harsh topography. Most of the fields are deep and tight, making extraction extremely difficult. The new projects rely on expensive EOR systems to extract what remains in the oilfields. PDO has more than 20 EOR projects.
PDO in early 2009 announced discovery of three oilfields. Taliah and Malaan West are among its Lekhwair cluster of fields in the north-west - part of the Upper Shu'aiba formation (Fm) which contains many of the reservoirs of PDO's main fields. Rabab South-East confirmed the preliminary results of well tests PDO mentioned in 2008. Oil production from Rabab South-East began in 2009 through existing facilities at Harweel field in the south.
Drilling and studies in 2008 enabled PDO to better estimate the extent of petroleum volumes at the Burhaan West and Fahud SW gas fields, as well as at the Budour NE oilfield found in previous years. The reservoirs of Burhaan West and Fahud SW have low permeability. As a consequence, the reservoir rocks first had to be cracked with extreme hydraulic pressure.
PDO's first EOR projects were in fields near Nimr, around Harweel, in Qarn Alam, at Marmul, and at Fahud. The Amal fields produce heavy oil from beam pumped wells with depths varying from 500 to 1,000 metres. PDO built an 800 CM/d water treatment plant for Amal West and Amal East. Two skid-mounted 200 t/d portable gas-fired steam generators provide the steam needed for the EOR system at the two fields.
PDO found Harweel in 1997 and since has found seven similar fields containing intra-salt carbonate stringers in a large 1,000 sq km area. It estimated the cluster contained an initial 1.8bn barrels in place of light and sour oils and re-trograde condensate. The cluster includes Shujirat, Sakhiya, Harweel Deep, Sarmad, Ghafeer, Dafiq, Dhahaban South, and Zalzala. PDO has drilled more than 60 wells in these fields and in Phase-1 has produced oil from four fields and injected gas in Zalzala to confirm the viability of miscible sour gas injection. During Phase-1, PDO produced about 18,000 b/d from the Harweel cluster.
Production could rise to more than 100,000 b/d once the Phase 2AB project is completed. The crude oils found in that cluster are some of the oldest on earth. PDO estimates a 10% ultimate recovery without miscible sour-gas injection which may increase to more than 30% with injection. The Harweel facilities will process very corrosive fluids, so that much of the installed equipment and piping is made from corrosion-resistant alloys.
PDO found Qarn Alam in 1972 and estimated that initial oil in place in the field's fractured carbonate reservoir was 1bn barrels. Without the thermal project, only 4% of the oil could be recovered from the field. But with its TAGOGD project, ultimate recoveries may exceed 32%.
In April 2007, PDO began work on a shake-up of its engineering operations by employing an in-house front-end engineering and design (FEED) office for the first time. Under the terms of the initial five-year cost-plus contract, the successful design firm was to assign up to 30 staff to PDO, working with existing staff and employees assigned from Shell (see the background in omt6OmanFieldsFeb4-08).
PDO has over 125 producing oil and gas fields tied to its production system in onshore Oman's four main oil fair-ways, which are as follows: (1) the north, along the border with the UAE and Saudi Arabia (extension of the Arabian Basin) including Thamama-related fields like the Fahud-Lekhwair-Daleel group; (2) the north-central groups in the Infracambrian Salt Basin, including the main producers like Yibal and fields centred on Natih-Shibkah; (3) the central and west-central groups, also in the Salt Basin, which include the gas-rich Saih Nihaydah; and (4) the south, in a Lower Salt Basin with fields of both very heavy and medium/light oils centred on the Marmul-Nimr-Rima-Jalmud trend.
All of PDO's wells now are horizontal. These and the use of 3D seismic have resulted in oil and gas finds in excess of expectations. The wells stretch 500m to 1.5 km along a reservoir, giving higher production with less water, and help in the search for or identification of additional reserves.