Norwest Identifies Dominant Gas Production Zones at Arrowsmith-2 Well

Australia's Norwest Energy NL reported Friday that evaluation of the Arrowsmith-2 dataset and well test results in exploration permit (EP) 413 in the onshore Perth Basin, Western Australia indicated that the Carynginia Formation and Irwin River Coal Measures (IRCM) are the dominant zones for gas production.

During the well test, the production logging tool (PLT) tested flow conditions over the range 8,858 feet (2,700 meters) to 10,830 feet (3,301 meters), including the perforated zones of the Carynginia, IRCM and High Cliff Sandstone (HCSS). These zones had a previously reported average commingled surface gas rate of 312,299 standard cubid feet per day, or scf/d (Oct. 2013), however the production logging program was the first opportunity to record down-hole contributions from each perforated zone.

The PLT program had several objectives, which included:

  • Determining dominant zones and establishing relative contribution of each zone
  • Verifying down-hole flowing conditions; and
  • Validation by inclusion and comparison with the pre-existing dataset

These objectives have now all successfully been met.

The hydraulic fracture stimulation program implemented at Arrowsmith-2 had five frac stages, referred to as Stages 1 to 5 (refer Table 1), all targeting different depth intervals within the well.

The PLT program was conducted across the perforated intervals of stages 1 - 4. This was the first opportunity to assess down-hole gas contribution from each specific perforated interval. PLT results across the Stage 1 perforations indicate the majority of gas produced from this stage as being produced from the perforations in the Lower IRCM as opposed to the HCSS as previously thought. The isotope and gas compositional data supports and validates the Lower IRCM as being the predominant gas source for Stage 1. This result high-grades the IRCM as the dominant gas producing interval.

Table 1 (Arrowsmith 2 hydraulic fracture stimulation stages)

  • Frac Stage 1: HCSS and Lower IRCM (Target Formations)
  • Frac Stage 2: Upper IRCM (Target Formations)
  • Frac Stage 3: Lower Carynginia (Target Formations)
  • Frac Stage 4: Middle Carynginia (Target Formations)
  • Frac Stage 5: Lower Kockatea - not tested during PLT program (Target Formations)

With two target intervals having the potential to produce significant quantities of hydrocarbons, the selection of the target zone and location to drill Arrowsmith-3 will be finalized by integrating the results of the 3D seismic acquisition program scheduled for the last quarter of 2014.

Norwest Energy CEO Peter Munachen said that the final test work conducted at Arrowsmith-2 and analysis of results had validated the Company’s high expectations for the proposed Arrowsmith-3 horizontal well and the way forward for the Arrowsmith field.

“Overall results at Arrowsmith-2 have been very encouraging. It is the first shale gas project in Western Australia, and through the efforts of our dedicated project team and support of the Joint Venture partners we have achieved all project objectives,” Munachen said.

“It is indeed a significant milestone to have achieved these objectives, which will assist in establishing the basis for the way forward” Munachen continued.

The results of recent exploration and evaluation at Arrowsmith-2 provide validation of geological assumptions and target formations, and will assist in developing an informed pathway for further evaluation of the Arrowsmith Field and defining potential for development.

Munachen said the final test results at Arrowsmith-2 had proven the shale gas concept. This was supported by the DeGolyer and MacNaughton estimated prospective resource of 2.6 Tcf (trillion cubic feet) for the Arrowsmith field (refer to ASX release dated June 11, 2013).

At present Arrowsmith-2 is being monitored for fluid levels and pressure build up in the well. No decision has yet been made by the joint venture as to the future use of Arrowsmith-2, however a number of options around different field development scenarios will be considered in due course.


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