Bougainville is a Western Tropical Pacific archipelago of one major islands and several smaller islands, located to the northeast of Australia and east of PNG.
As a result of having to rely on expensive, imported diesel for power generation, electricity on Bougainville is expensive and generally energy users require diesel power generators. Bougainville needs better, domestic access to energy and affordable energy will support economic development including power needed by major mining developments.
The country has a population of ~300,000 with a developing economy but adversely affected by cost and limited availability of electricity. It has been estimated that less than 1% of the population are connected to an electrical grid which means people may have challenges with Energy Poverty and Affordability.
Bougainville is fortunate to have significant mineral deposits including gold and copper mineralisation associated with porphyritic microdiorite bodies intruding agglomerate belonging to various volcanic systems along the island. The mineralization processes involved various alteration types and hydrothermal phases. Large scale mining requires significant amounts of electrical energy to power the equipment and unless geothermal energy is identified and developed, these mines would have to import large amounts of expensive carbon based energy like diesel.
Geology
Bougainville is located on a tectonic plate boundary between the Pacific Plate and the Australian Plate. These two plates have converged on each other over tens of millions of years ago. First ~45 million years ago, the Pacific Plate subducted beneath the Australian Plate (producing the North Solomon Trench / Melanesian Trench and “birthing” Bougainville), then ~10 million years ago, the Australian Plate (with its subplate Solomon Sea plate) subducted beneath the thicker Ontong Java Plateau portion of the Pacific Plate (producing the more recent volcanic structures on Bougainville). The island is ~120km long with multiple active volcanoes and many other volcanic structures, some with existing heat flows demonstrated by hot springs and fumaroles.
A current subduction geological view of Bougainville with deep sea trench on the southwestern side and a line of volcanic structures down the middle of the island is shown in the illustration below. The magmatic activity shown would be responsible for producing the volcanic structures and elevated heat flows into shallow hydrothermal reservoirs which would be the initial exploration targets.
Seventeen post-Miocene volcanoes have been identified with one currently active volcano Bagana, one large volcano Billy Mitchell that erupted twice within the past thousand years, two volcanoes Balbi and Loloru having hot spring and fumarolic activity, and others showing no signs of activity. From the presence of these surface manifestations, it was apparent that subsurface hydrothermal reservoirs exist that might be able to be utilised to produce clean, renewable energy in the form of geothermal electricity.
Project
The proposed Bougainville Geothermal Project will have several project phases including some of the activities listed below (but not limited to this selection):
• Exploration
o Aerial surveys (i.e., LIDAR, visual, thermal)
o Geological field surveys
o Geophysical field surveys (i.e., Aeromagnetic, Magnetotelluric, Audio Magnetotellurics, Atomic Dielectric Resonance Scanning, etc.)
o Detailed technical studies and simulation and analytical models
o Surface surveys (topography, drilling location and flowline route surveys)
o Appraisal Wells (shallow boreholes/slim hole wells, production/injection testing)
o ESIA (exploration, drilling, construction and installation of power generation facilities and transmission line facilities)
o Front End Engineering Design (FEED)
• Development
o Updated technical studies and simulation and analytical models
o Development Wells (larger diameter production wells and potential repurposed/modified slim hole wells)
o Facilities engineering, analyses and designs
o Fabrication and construction of infrastructure, equipment, flowlines
o Pre-commissioning and Commissioning / Start-up
• Operations
o Safety and control systems monitoring
o Well testing and monitoring
o Flowline inspections and maintenance
o Production facilities inspections and maintenance