| Title | Preliminary Assessment of the Geothermal Signature and ECBM Potential of the Huntly Coalbed Methane Field, New Zealand |
|---|---|
| Authors | Sadiq J. Zarrouk and Tim A. Moore |
| Year | 2007 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | |
| Abstract | The Huntly coalfield is being prospected as a coalbed methane (CBM) play. Five exploration wells and six production appraisal wells were drilled between late 2005 and mid 2007. A number of well tests were conducted (completion, interference and production testing) including measurement of the stable downhole temperature gradients. The temperature data have shown that the field has a gradient of 52 to 55 C o /km which corresponds to an average natural thermal flux of 100 mW/m2. It is believed that the Mesozoic-age greywacke basement acts as a constant pressure boundary affecting the water and gas production in the overlaying coal seam in areas where coal measures directly overlay the basement. The Na-K, K-Mg geothermometers imply a deep geothermal reservoir temperature of more than 90 C o. This can be related to the close proximity (within 120 km) of the Huntly coalfield to the Taupo Volcanic Zone (TVZ). Temperature gradients along with other reservoir data have been used to create a three-dimensional numerical model of the Huntly coalfield CBM play. The model is used to forecast gas and water production under different development and stimulation scenarios. The model is also being used to investigate enhanced coalbed methane (ECBM) recovery using carbon dioxide, nitrogen or other possible combustion-flue gas compositions. |