We’ve been generating electricity from geothermal activity on the Kawerau field since 2008. During that time we’ve learned more about the geothermal reservoir deep within the earth.

Wells have a finite lifespan and corrosion can mean that wells are required to be re-drilled and replaced over time.

Therefore, as part of our sustainable management of the field, we are drilling three more wells - two production wells (takes steam and fluid to run the power station) and one reinjection well (puts fluid back).  

These wells are “make up” wells – maintaining current capacity. We are drilling two production wells and one reinjection well at Kawerau.

It takes approximately 2 months for the rig to be set up, drill down, establish a well head and disestablish the rig. We are drilling three wells in the Kawerau geothermal field at this time.

Most of the steam and fluid is returned to the reservoir, deep underground. One of the three wells we are drilling now is a reinjection well, and there are others in the field. 

This work will be carried out in accordance with Bay of Plenty Regional Council and District Council resource consent conditions and district rules. There are strict rules in place around our whole operation at the power station, including well drilling. 

The drill rig is a 2007 Drillmec HH300, 272 metric ton lifting capacity and capable of drilling 5500m deep.

The Rig is like adult Lego! It gets pulled apart and transported to site in ~100 truck loads and then reassembled with four cranes and a team of 30 people per day. 

The rig has come from our geothermal power station at Rotokawa, north of Taupō, where it drilled one well (RK39) to 2200m deep.

The rig crew is made up of 40 people, mostly New Zealanders working on a shift basis.

Local contractors have been helping us with maintenance and other activities at the Mercury power station and the geothermal field. Local contractors have also been engaged for the earthworks and waterlines associated with the drilling pads and camp.  

While a lot of planning and science has gone in to the drilling program, these wells reach kilometres under the earth. When you’re going that deep, sometimes unexpected stuff happens and contingency plans need to be executed, which could impact the drilling schedule.

Drilling work is very specialist, and only three other drill rigs in NZ are capable of this work. IDC have drilled in New Zealand previously in 2010-2012 (Ngā Tamariki power station) and in 2018, and most of the crew are from New Zealand. 

IDC was awarded the contract to complete these works in Kawerau as well as at the Rotokawa and Ngā Tamariki geothermal fields.

Geothermal wells have a small surface footprint, while extending deep underground. Short term during the drilling operation there may be higher noise, lighting and dust levels near the drill site, but in each case this is carefully mitigated and monitored by the on-site team. 

We are confident that there is no additional risk of seismic events from drilling these three deep but extremely narrow wells. In Kawerau, GNS believe that the earthquake swarm in March this year was due to the movement of active faults and not related to volcanic unrest or geothermal activity. Please see here for more information.

The town’s water supply will not be impacted by our activity.

We have a careful plan, including noise bunds, light barriers and dust control sprayers.

There is positive impact on the community too by utilising local contractors where possible to support the specialist drilling crew such as Waiotahi contracting and Crossroads. 

We’ve talked to local residents, businesses and iwi who might be impacted by the drilling or moving the drilling rig around. We’ve put flyers and posters out into the community and also got the message out using social media, paid advertisements in The Echo, and our website. We will continue to communicate about our progress.

In the short term we’re proud to take our place as a supporter of the awesome Kawerau Christmas in the Park, and we’re looking to do more next year. We want to  build and continue to build good relationships in the town. We’re listening to groups in the community to understand how we can participate in the community. 

For 15 years Mercury has been running the Kawerau geothermal station, taking care of the environment above ground, and ensuring that the below-ground taonga of the geothermal field is managed and monitored for ongoing health and sustainability. 

You can email us at geothermal@mercury.co.nz.