Charles Ellinas, chairman of the Cyprus National Hydrocarbons Company, said that crews aboard a drilling platform – anchored in Cypriot waters south of the island – were working to repair a glitch which has temporarily stalled the production test. The drill stem test, as it is known, had been scheduled to start last Thursday 5th September, but was put on hold due to a mechanical malfunction. Noble is reportedly reviewing its options: either to repair the technical problem or replace the spare part that failed to operate. The US company has the spare part on hand if necessary. Noting that such glitches are not out of the ordinary, Ellinas told the Cyprus News Agency he has received assurances from Noble Energy – operators of the offshore gas prospect – that the production test would be up and running by the middle of this week.
A drill stem test (DST) is a procedure for isolating and testing the pressure, permeability and productive capacity of a geological formation during the drilling of a well. The test is an important measurement of pressure behaviour at the drill stem and is a valuable way of obtaining information on the formation fluid and establishing whether a well has found a commercial hydrocarbon reservoir. As part of the DST, a flame was expected to be ignited at the rig, a process known as ‘flaring’. Flaring gives clues as to the content of the natural gas in the bedrock. It’s understood the faulty equipment is a valve on the drill column, or pipe, that transmits drilling fluid to the drill bit. The column is now being retracted (from a depth of about 5.7km) to replace or repair the valve. The repairs are necessary to stabilise the pressure before fluids can be pumped to the surface. Once that is done, the next phase is flaring. Once flaring gets underway, it’s set to last about a week.
Gas samples will then be sent to Noble’s labs in Houston for analysis, and preliminary findings on the hydrocarbon content should be out two to three weeks later. Calculations on the quantity of the gas – gleaned from data on fluid pressure and flow – take longer. The production test at the A-2 well is part of appraisal drilling in the Block 12concession. The field has a gross mean average of 7 trillion cubic feet (200 billion cubic metres) of natural gas with an estimated gross resource range of 5 to 8 trillion cubic feet.
Officials have said that proved reserves of 6tcf would be necessary to monetise the prospect. Over the past couple of weeks certain media outlets have been rife with speculation that the quantities of gas within Block 12 are substantially lower than initial estimates. Citing its sources, Kathimerini claimed on Sunday that the prospect is now thought to hold anywhere from 3.5 to 5 tcf.
Last week energy minister Giorgos Lakkotrypis said the government would be making its plans depending on the quantity of gas discovered. “We are ready for all scenarios,” Lakkotrypis said at the time, though he did hasten to add that a “disappointing scenario” was not possible. The minister’s somewhat evasive comment fed into the conjecture over the quantity of gas, with the paper hinting that Lakkotrypis was trying to cover all the bases – just in case.
Sources tell the Mail, however, that the guesswork is unfounded. They said moreover that Noble has been trying to trace the source of the rumours. The same sources – who wished to remain anonymous – said the speculation likely grew out of statements on the possible need for a second appraisal well at the prospect. But additional appraisal wells are not carried out because initial assessments may be unsatisfactory; they can likewise be carried out if results exceed expectations.
The sources cited the example of Israel’s Leviathan field, where Noble – having revised upward its reserve estimates from an initial appraisal well – went on to carry out more appraisal drilling. “Bottom line: you could find more gas and still go for a second appraisal,” said the sources, adding that the purpose of appraisal work is to narrow the gap of the estimates. And given that the Cyprus prospect covers approximately 40 square miles and the morphology of the bedrock needs to be analysed, a second appraisal well would not be unusual, the sources pointed out. They also drew attention to the fact that months ago – well before the start of the appraisal drilling- Noble chairman and CEO Charles Davidson told a conference there was approximately a 30% chance for a second appraisal well.
Source: Cyprus Mail
