BHP Billiton Ltd. and its partners have begun drilling the Angostura-1 well in Angostura Phase III as it attempts to meet its contractual arrangements to provide natural gas to the downstream plants at Trinidad and Tobago’s Point Lisas Industrial Estate.
The well is being drilled in 5,000 ft of water offshore Trinidad and Tobago’s east coast and the structure is south of its producing area called the Greater Angostura development.
During the drilling phase, which is expected to last 6 months, operator BHP is expected to drill three development wells in an area believed to be all gas with no associated liquids.
The development will not BHP’s overall gas production but will simply replace declining wells and ensure it can keep its production at a level required to maintain its contracts.
Currently BHP produces nearly 400 MMscfd and just more than 7,600 bo/d in Trinidad and Tobago. Some of the gas from Angostura Phase III will be reinjected into the oil-producing part of the Angostura field to assist in the continued lifting of the oil and a slowing in the rate of decline of the reservoirs.
The Greater Angostura development is not one contiguous block but one with several faults and therefore the development is in another of the fault blocks that make up the Greater Angostura field.
Phase III is estimated to contain 500 bscf of recoverable reserves, with the entire Angostura development estimated to have contained 1.75 tcf of gas.
Greater Angostura field lies in 36-46 m of water on the continental shelf, 37 km east of Trinidad and in the eastern Trinidadian sector of the Eastern Venezuela basin.
The shallow-water integrated oil and gas field development is part of Trinidad Offshore Block 2c. It is operated by BHP Billiton (45%) on behalf of joint venture partners. BHP first signed a production-sharing contract on Apr. 22, 1996, and acquired a 3D seismic survey in 1997. BHP and its partners’ license to operate the field continues until 2021 under a PSC with the Ministry of Energy and Energy Affairs.
The Greater Angostura field has a production life expectancy of 19-24 years.
The discovery well, Angostura-1, was drilled in 1999. This intersected 950 ft (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 and 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.
During the 6-year exploration phase of the PSC a total of four exploration and three appraisal wells were drilled, discovering significant oil and gas resources within a large faulted structure known as the Greater Angostura structure.