The Harweel cluster, located in the south, is one of a number of areas highlighted for investment under PDO’s recovery plan. The area comprises seven separate oil fields with a total of nine reservoirs to depths of between 3-5 kilometres. The fields are estimated to contain 2,000 million barrels of stock-tank oil. Only 10 per cent of this oil could be tapped by normal production techniques. PDO plans to increase its recovery rate to around 50 per cent with the use of enhanced oil recovery (EOR) miscible technology.
‘The development of the Harweel cluster is being carried out through a stepwise approach,’ says Steven van Rossem, project manager. ‘The first phase development, known as early development facilities (EDF), is being executed at the moment and will result in first oil from the Harweel area by the first quarter of 2004. This involves tying back four of the reservoirs in the cluster through a long-distance pipeline to the Birba production station. The first phase development will deliver 2,000 cubic metres a day of oil.’
The local GPS is the main engineering, procurement and construction (EPC) contractor for the facilities and pipelines infrastructure for phase 1. Galfar Engineering & Contracting is carrying out the EPC package for the electrical works and Japan’s Yokogawa Europe is handling the automation package.
PDO is yet to make a firm decision on whether to press ahead with the phase 2 programme, which is expected to require significant investment in order to build compression stations and associated power supply units. ‘There is no power grid in Harweel as it is a greenfield area and after phase 1 there will still be no large-scale facilities in the area. However, phase 2 will require power to run the high-pressure compressors for the gas flooding,’ says Rossem.
EOR and gas miscible flooding are key elements in the government’s plans to boost production from its present lows of about 900,000 barrels a day. ‘In a miscible gas flood there is a reaction between the injectant and the reservoir oil. The injectant is in fact a solvent. It is a kind of chemical cleaning of the reservoir rather than just blowing gas through to deliver more oil. Miscible gas injection will provide much higher recovery rates than conventional gas injection,’ says Rossem.