Offshore exploration wells
Deasy asked for the number, locations and yields of offshore exploration wells. Colley said 59 wells had been drilled and cautioned that traces, shows and flows are distinct results that cannot be interpreted in isolation.
asked the Minister for Energy the number of bore-holes drilled off the Irish coast over the past ten years in the search for oil and gas; the location of each bore-hole which has shown traces of hydrocarbons; and the yield in each case.
Comment on this
59 hydrocarbon exploration wells have been completed off the Irish coast over the past ten years.
There have been traces of hydrocarbons recorded in most of these wells. However, there is a big difference between a "trace" and a "show" of oil, and between a "show" and a "flow". These are terms used in the industry in relation to exploration results which cannot be properly interpreted in isolation from other information and data. For instance a flow rate is not indicative of the size of the structure in which it occurs. Nor is a relatively high flow rate from one well confirmation that the deposit will prove commercial. The following information must, therefore, be viewed in that context.
A well drilled in Block 48/25 in the Celtic Sea in 1971 led to the discovery of gas deposits off Kinsale Head. Two further wells were drilled in 1972 and 1973 to appraise and further delineate the structure. These wells were drilled in Blocks 48/20 and 49/16. This led to the declaration of a commercial gas accumulation off Kinsale Head. The field came on stream in 1978 and the operator contracted to supply 124 million cubic feet of gas per day over a 20-year period.
The following wells completed in the Celtic Sea had hydrocarbon flows on test.
A well drilled in the Ardmore structure in Block 49/13 in 1974 flow tested gas at a daily rate of 119 thousand cubic feet. A further well in the same structure in Block 49/14 in 1975 flow tested gas at a rate of 8.81 million cubic feet per day.
In the Seven Heads structure two wells were completed in 1974. One in Block 48/24 flowed 780 barrels of oil per day on test and up to 10 million cubic feet of gas per day. The second well, drilled in Block 48/28, flow tested oil at a rate of 1,550 barrels per day.
These two structures were considered too small and too complex to justify economic development.
Of the 14 wells drilled to date in the Porcupine Basin three flow-tested hydrocarbons as follows:— 730 barrels per day from a well drilled on block 35/8 in 1978; 5,500 barrels per day from a well drilled in block 26/28 in 1979; 1,500 barrels per day from a well drilled in 1980— also in block 26/28.