Singapore-listed Linc Energy Ltd. provided on Wednesday an update on the drilling operations in the Arckaringa Basin in South Australia. The Eba 1 vertical exploration well (PEL121) is the second of the three well program and is expected to be completed in approximately 12 days at an expected total depth of approximately 8202 ft. As of 16:00hrs 13 January the main hole rig was drilling ahead in the pre-Permian Formation at a depth of 5925 ft. The drilling has been slow since intersecting the pre-Permian, averaging 6.5 - 19.6 ft per hour due to hard and abrasive sediments. Recent rainfalls forecasted in the north-east pastoral district have not materially impacted drilling operations to date.
The primary objective of the Eba 1 well is to confirm the stratigraphy of the pre-Permian sediments and evaluate their source rock potential. Initial interpretation indicates Eba 1 intersected the Officer Basin equivalent of the Cambrian Ouldburra Formation at 4087 ft. The major lithology’s recorded include interbedded sandstone, siltstones and anhydrite with minor carbonaceous siltstone bands increasing in abundance with depth.
Prospective formations underlying the Ouldburra Formation in the Officer Basin include the Neoproterozoic Tanana Formation, the Karlaya Limestone and the Dey Dey Mudstone; all of which have recorded oil shows (in offset wells located 124 miles or 200km to the North West). The presence of these intervals under the Arckaringa Basin is unknown at this time as all previous exploration generally terminated in shallower Cambrian sediments. For this reason, the data obtained from drilling the Eba 1 well through these previously unexplored intervals is an important milestone in the company’s current exploration program.
Overview of Program
The three well exploration program is focused on three sections within the organic rich, highly prospective Boorthanna trough. The target formations (Stuart Range, Boorthanna and Pre Permian) formed the basis of the prospective resources separately identified by both Gustavson Associates and DeGolyer and MacNaughton. To date, no previous drilling has intersected the formations at depth and the results of these wells will be critical to understanding the basin in detail.
Upon reaching the total depth of each well, an extensive logging program will be completed to evaluate the hydrocarbon resource potential. Cuttings and core recovered during drilling will be sent for analysis including:
- Geochemistry – to confirm thermal gradient projections and source rock quality
- Geomechanics – test rock strength of source formations
- Porosity and Permeability – reservoir characterisation
Assessment of the data collected in this first phase of drilling will determine the next development steps.
Each well will be completed in two sections with the initial “pre-collar” drilled and “cased off” prior to a larger rig continuing to TD and completion. The purpose of drilling the wells in two sections is to ensure the integrity of the region’s sub-surface water systems as a priority. The method of completing the program in two distinct consecutive stages was selected as it is considered both best practice and cost effective. The full drilling program is expected to take four months.
Adapted from press release by Joe Green