The plugs in the intervals are now being drilled out and the company expects the 'flow-back' phase will be complete in 3-to-4 weeks, with flow tests running for a further 4-to-5 weeks after that.
"We are very pleased to have successfully completed this 10 stage frac operation in Ukraine," said chief executive Dr Paul Davies.
"Conditions have been difficult but overall the execution has been better than anticipated.
"Seven of the frac stages have achieved or exceeded design predictions, two were below expectations and only one was unsuccessful.
"The next few weeks of clean-up and flow stabilisation will be critical and we are encouraged that the well is already flowing gas to surface together with frac fluids."
City broker Oriel Securities reckons JKX's current share price underplays its potential and that the outcome of the R-103 well could be a catalyst.
By Oriel's estimation a success would add around 65p to the group's valuation, which currently stands at 124p per share.
That valuation itself is already way off what the market thinks the share is worth.
On AIM, JKX shares edged just 1% higher to trade at 67.25p.
The gap between the market's valuation and the broker's will narrow, Oriel says, as JKX ramps up production and demonstrates that its operational problems are behind them.