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Serinus hits hydrocarbons onshore Tunisia

04th November 2014

Serinus Energy has reported positive preliminary results from the Winstar-12bis (WIN-12bis) well onshore Tunisia

Serinus hits hydrocarbons onshore Tunisia
Early analysis of the data acquired from electric logs, full diameter core and drilling records indicate that the well has encountered 79 metres of oil bearing reservoir in the Upper Hamra, Lower Hamra and El Atchane formations, above an oil to water transition zone present throughout the lower zones in the well

The well has reached its total depth of 3,855 metres, with the presence of hydrocarbons was initially confirmed by fluorescence exhibited in the recovered core and drilling cuttings, and subsequently with open hole wireline logs.

“Winstar-12bis is the first well drilled by Serinus in Tunisia since the Winstar acquisition, and initial drilling and log results look promising,” said Jock Graham, executive vice president and chief operating officer of Serinus.

“However, we still need to establish how the well will perform once on production and to this end, we are completing the well in order to undertake a production testing programme.”

Early analysis of the data acquired from electric logs, full diameter core and drilling records indicate that the well has encountered 79 metres of oil bearing reservoir in the Upper Hamra, Lower Hamra and El Atchane formations, above an oil to water transition zone present throughout the lower zones in the well.

Average reservoir porosity is 10 per cent. An additional 14 metres of oil bearing reservoir have been identified within the transition zone, and the nuclear magnetic resonance tool has also unexpectedly indicated moveable oil below the base of the transition zone.

Further testing will be required to understand the nature of the hydrocarbons in these lower sections. The well is being completed, after which the rig will move immediately to Winstar-13 (WIN-13).

Once the rig is off location, WIN-12bis will be put on an extended production test.

During drilling, 23 metres of core were cut and recovered from the Azel and Upper Hamra zones at depths between 3,688 – 3,715 metres, after which drilling resumed to total depth and the well was logged.

The core samples showed fluorescence, indicating the presence of hydrocarbons in the Upper Hamra reservoir. Due to a combination of certain characteristics of the formation and reservoir fluid composition, a detailed petrophysical analysis was required to determine the thickness and porosity of the reservoir zones.

That analysis was completed on November 1, 2014, and will be updated and adjusted based on production testing and the final core results. The full core analysis is expected to take up to two months to complete.

The logs are comparable to wells previously drilled in the Sabria Field, and indicate that the well has its best developed porosity in the Lower Hamra formation between 3,728 - 3,760 metres.

Logs also confirm that this well contains the full Upper Hamra, Lower Hamra and El Atchane reservoir sections -other wells have had the Upper and Lower Hamra partially or wholly eroded. WIN-12bis is also the highest structural penetration of the reservoir section in the Sabria Field thus far, some 41 metres higher than Sabria-N3, the next highest in the field.

A fracture system was detected in the Upper Hamra by drilling breaks and lost circulation during coring, and was subsequently confirmed by the imaging log.

The well has been plugged back to 3,784 metres, and is being completed for open-hole production testing.

Once the rig has moved off, WIN-12bis will be tied into the recently constructed flowline and placed on production through the Sabria Central Processing Facility. Testing will continue during the drilling and completion of WIN-13, which is expected to take 73 days. If production and pressure data from the test so dictate, the rig may be brought back to WIN-12bis to drill a horizontal leg.

 “We also experienced some delays while drilling this well due primarily to equipment failures associated with the rig, however those issues have been rectified and we anticipate better drilling productivity on Winstar-13, which will spud immediately after WIN-12bis is completed and the rig move finished,” Graham added.

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