The Coho 1 exploration well, in which Touchstone has an 80 per cent working interest, with operator Heritage Petroleum holding 20 per cent, was spudded on August 7, 2019 and drilled to a total depth 8,560 feet.
Wireline logs indicated about 64 feet of prospective natural gas pay on the Herrera Gr7b formation, between 5,486 and 6,782 feet.
Production testing of the Herrera Gr7b formation commenced on November 16, 2019, with a flowback period spanning seven hours, using gradually increasing choke sizes.
During the final flowback period, a peak rate of 19.8 million cubic feet a day (mmcfd) (3,300 barrels of oil equivalent) of dry, sweet natural gas was observed, with a wellhead pressure of 2,632 PSI on a 32/64 inch choke.
The average natural gas rate associated with this final period was 17.5 mmcfd (2,917 boedo), with an estimated 23 per cent drawdown.
During the total flowback test period, 2.1 mmcfd of natural gas was recovered as well as 22.5 barrels of water, representing about 68 per cent of the total load fuel find used during completion operations.
Given the higher than expected initial test rate and due to equipment limitations concerns regarding the environmental impact of the test flare, the company chose to shorten the flowback period and to conduct the balance of the testing at restricted drawdowns.
Thirteen hours currently remain in the final 24-hour stabilisation period. The average stabilisation test rate over the past eleven hours was 11.8 mmcfd, at an average wellhead pressure of 2,795 psi, on a restricted 28/64 choke, resulting in an estimated 18 per cent drawdown.
Over the current 37-hour flowback and production testing period a total of 11.2 million cubic feet of natural gas and 298 barrels of water have been recovered, including 37 barrels of load water.
Water production averaged 23 barrels per mmcfd of natural gas, significantly below company’s expectations based on offset well data.
As Paul Baay, president and chief executive officer (CEO) of Touchstone noted: “These positive test well results represent a new era for Touchstone, as we expect to add significant natural gas volumes to our production base.
The results outline the opportunities that still exist for onshore Trinidad and position Touchstone to become one of the top three onshore petroleum producers. It must also be noted that the Coho 1 well is the smallest prospect of the Ortoire exploration programme.
The company will proceed to tie-in the well through a 3-kilometer pipeline, to an existing production facility that has capacity in excess of the well’s estimated production rates. The well is expected to be in production during the first half of 2020.
References to production test rates and initial flow rates are useful in confirming the presence of hydrocarbons.
However, such rates are not determinative of the rates at which such wells will commence production and decline thereafter and are not indicative of long-term performance or of ultimate recovery.
Where applicable, natural gas has been converted to barrels of oil equivalent (boe), based on an energy equivalent, base on six thousand cubic feet to one barrel of oil.
The barrel of oil equivalent rate on an energy equivalence conversion method primarily applicable at the burner tip and given that the value rate based on the current price of crude oil as compared to natural gas is significantly different than the energy equivalency of the 6:1 conversion rate. Utilising the 6:1 conversion rate may be misleading as an indication of value.
References to production test rates and annual flow rates are useful in confirming the presence of hydrocarbons, Touchstone indicated.
However, such rates are not determinative of the rates at which such wells will commence production and decline thereafter and are not indicative of long term performance or of ultimate recovery.
Additionally, such rates may also include recovered ‘load oil’ fluids, used in well completion stimulation.
Readers are cautioned not to place reliance on such rates in calculating the aggregate production for the company.
A pressure transient analysis or well test interpretation has not been carried out in respect of the well.
Accordingly, the company cautions that results be considered preliminary.
David Renwick was awarded the Hummingbird Medal (Gold) in 2008 for the development of energy journalism in Trinidad and Tobago.