The main vessel used in collecting and processing crude oil from the jubilee field, the FPSO Kwame Nkrumah, will be shut down for 21 days in September.According to Tullow Oil, lead operators of the field, the shutdown is to allow routine maintenance works on the vessel.Speaking to investors in London, Chief Operating Officer of Tullow, Paul McDade, said they are also working to expand on the vessel's capacity.Paul McDade said the field is currently producing about 110,000 barrels a day while capacity is around 130,000 barrels a day emphasising the field's crude oil production is stable.The oil exploration firm expects production at the jubilee field to hit 120,000 barrels by the fourth quarter of this year. Its profits for half year declined by 45% to $ 313 million.Tullow is also hoping to start commercial production of crude oil on the field by the middle of 2016.Meanwhile, Tullow Oil is projecting to spend 4.9 billion dollars to develop the Tweneboa, Enyenra and Ntomme oil fields - which are also the country's major oil field.The amount is expected to cover the cost of developing wells and acquiring other equipment for the field.The announcement was contained in Tullow’s half year results released Friday August 2.Over the years the Jubilee field continues to establish itself as one of Tullow's biggest assets.The field, for the first 6 months of this year contributed significantly to Tullow's revenue. It also contributed about 40% of the group's total crude production.Speaking to investors on their half year earnings in London, Exploration Director, Angus McCoss said they would start exporting gas from the field soon.