BHP Billiton is expected to increase its crude production by between 2,000 and 3,000 barrels per day by the end of May, according to well-placed sources at the company. Sources say the increase will come about because the company will bring on production an infill well that it recently drilled in the Canteen area of its Angostura field. Sources told the Business Guardian: "We expect that the infill well will add another 2,000-3,000 barrels of oil per day to our production. This is the third infill well we have drilled. Last year we drilled two in the oily part of Kairi and those are already on stream and we expect this one to come on stream by next week." The increase in crude production will be welcomed news for Energy Minister Kevin Ramnarine whose mantra has been the need to increase crude production.
Ramnarine has argued there is a need for an increase in oil production because the energy value of a barrel of oil is significantly more than that of gas and, in the circumstances, with oil prices remaining high, the country needs to increase oil production to benefit from the higher global prices. The Business Guardian was told that it meant that BHP Billiton's production, which has averaged 12,500 bo/d for 2012, will increase to closer to 15,000 bo/d even though that is likely to hold for just over four months. The Greater Angostura field is located in 36-46 metres of water on the continental shelf, 37 kilometres off the easst coast. It is operated by BHP Billiton its first discovery well, Angostura-1, was drilled in 1999. This intersected 950 feet (gross) of gas pay. The hydrocarbon potential of the structure was confirmed by the drilling of Aripo-1, Kairi-1, Canteen-1, Kairi-2, Angostura-2 and Canteen-2 wells. Each of these exploration/appraisal wells also intersected sands.
The Kairi and Canteen fault blocks contain most of the oil while Aripo has a thin oil rim overlain by a significant gas cap. Sources say the challenge that BHP Billiton and its partners have had to wrestle with is the extent of faulting in the block. This means that the hydrocarbons have been trapped in several smaller faults that compartmentalise the oil. This means that for the company to access the oil, it will have to drill more wells than normal in a situation where there were larger faults. Additional wells mean greater costs and that more oil would have to be eventually left in the ground than would have been the case with less faulting. However, company sources say BHP Billiton has done well to stabalise the production, which declined rapidly in the first three years from 60,000 bo/d to 12,000/d.
"For us this is a management process. We have had to be careful in the way that we manage the reservoir. It has involved the opening and closing of wells. It has involved the tight control of the gas pressure that we have in the well because we don't want to produce the oil too quickly and then damage the reservoir, so it has been a virtual juggling act for us, but we feel we have stabilised the situation." Sources say when Angostura was discovered, both the exploration and appraisal wells suggested a much larger discovery than was eventually proven by the development wells. "The data from exploration and appraisal wells suggested a much larger reservoir, but when we drilled the developmental wells, we learned more information. You have to understand that the quality of the seismic was not great because of the fractured rocks that were broken up into small faultblocks. We discovered that the top of the reservoir was lower than anticipated and the gas/water content remained the same."
According to sources, the water contact at the top of reservoir was lower so the volume of the hydrocarbons was also lower. BHP Billiton initially thought it had 160,000 million barrels of oil in Angostura and three trillion cubic feet of gas, but that has been reduced dramatically. The company also sells 220 million cubic feet of natural gas a day to the National Gas Company.
ENERGY REPORTER
