Describing the test results as “disappointing”, the junior explorer said the operator has released the rig, having cased and suspended the well while it decides whether to undertake further testing.

“The test results have been disappointing considering the impressive oil shows obtained during drilling and the indications of hydrocarbons from wireline log interpretations,” Eureka said.

“The tests suggest that the Garzan fractured limestone reservoir at this location has a column of heavy oil which may not be capable of production due to a combination of low reservoir permeability and high oil viscosity.”

Despite the results, Eureka said the presence of heavy oil was encouraging, as further updip exploration could discover producible oil trapped in structural culminations.

Koyunlu-1 is centrally located in a 25km-long trend of structural highs at target Garzan and Mardin Formation level, the company said.

As a result, the joint venture is currently looking at acquiring new seismic data to help it locate a second well.