Geothermal Exploration in Taranaki and Waikato: Unlocking New Energy Opportunities in New Zealand New Zealand is expanding its geothermal ambitions beyond the country’s established development zones. Two Māori-led exploration projects in Taranaki and South Waikato have received a combined NZ$5.95 million in government grants to investigate previously underexplored geothermal resources and assess their potential to support regional growth, energy resilience, employment, and decarbonisation. The initiatives reflect a broader shift in geothermal development. While New Zealand’s geothermal industry has traditionally focused on high-temperature resources suitable for electricity generation, the new projects will also examine lower-temperature heat that could serve industrial, agricultural, commercial, and community applications. Government Funding for Two Exploration Projects The New Zealand Government has allocated NZ$3 million from the Regional Infrastructure Fund to the Taranaki Ge...
Mastering the Subsurface: A Geothermal Reservoir Engineer's Insights on EGS, Stimulation, Digital Twins, and the Future of Clean Baseload Power
Geothermal energy is often called the “quiet backbone” of the clean energy transition. To understand the science, challenges, and innovations driving this sector, we spoke with a seasoned geothermal reservoir engineer with experience spanning the Andes, Nevada, Utah, and volcanic fields worldwide. Here’s what they shared.
By: Robert Buluma
This interview was conducted by Robert Buluma, Founder of Alphaxioms. The responses were provided by Jerjes Porlles, Ph.D., Regional Technical & Business Development Manager – Latin America at Avasthi & Associates, Worldwide Energy Consulting.
1. What sparked your passion for geothermal reservoir engineering, and did you ever imagine yourself working in some of the world’s most challenging geothermal fields?
My passion was sparked during my early career in the petroleum industry, specifically in reservoirs. I was fascinated by the subsurface—how fluids move, how heat and pressure interact but it wasn’t until I worked on projects in Peru that I realized geothermal offered the chance to apply my skills to clean energy. I never imagined I would later work on Enhanced Geothermal Systems (EGS) projects in Nevada and Utah or Andean volcanic fields, where the geology is as unforgiving as it is exciting. Those challenges became a source of motivation rather than a source of fear.
2. Looking back, which project pushed you to your limits and what did it teach you about yourself and the industry?
A project in Nevada, where we modeled a reservoir under extreme conditions, truly tested me. We had to integrate geomechanics, stimulation modeling, and uncertain thermal recovery forecasts. It taught me that adaptability is as important as technical expertise. The industry is full of unknowns, and resilience is built by embracing them, not resisting them.
3. If you could go back in time, what advice would you give your younger self starting in this field?
I’d say: “Don’t fear complexity. Chase it.” The more complex the reservoir, the more you’ll learn. And, importantly, I would tell myself to build strong collaborations early—because geothermal is never a one-discipline job.
4. Can you share a moment when reservoir modeling or simulation completely changed the direction of a project?
Yes, during a simulation of a fractured geothermal system, the initial plan was to stimulate multiple wells aggressively. The model, however, revealed rapid thermal breakthrough if we followed that strategy. By re-optimizing injection and production spacing, we extended project life by years. That one model saved millions and demonstrated that simulation is not just academic it is a survival tool.
5. Have you ever faced a situation where enhancing permeability didn’t go as planned? How did you overcome it?
Absolutely. In one stimulation test, induced fractures propagated away from the desired reservoir zone, causing poor injectivity gains. Instead of repeating the operation, we integrated microseismic monitoring with adaptive modeling to redesign the stimulation in real time. The next stage succeeded, teaching me that feedback loops between field data and modeling are essential.
6. What’s the one reservoir challenge that keeps you up at night, even after years of experience?
Sustainability. We can always produce heat, but doing so without depleting the reservoir or causing induced seismicity is the tightrope we walk. Balancing aggressive targets with long-term reservoir health is an art as much as it is science.
7. In your experience, what is the most misunderstood aspect of geothermal reservoir management by outsiders?
That geothermal is “free heat forever.” Many people underestimate the complexity of maintaining productivity and sustainability. Reservoirs are dynamic, and if poorly managed, you can lose capacity quickly. It’s not just drilling a hole into hot rock.
8. How do you decide whether a geothermal site is worth the risk and have you ever been proven wrong?
We weigh geoscientific data, stress regimes, reservoir modeling, and economics together. I was once overly optimistic about a site in the Andes where surface heat flow data looked ideal. But drilling revealed a tight formation with poor permeability. It reminded me that nature always humbles engineers.
9. Can you share a story where data-driven decisions turned a struggling project into a success?
During my work on an Enhanced Geothermal System (EGS) project in Nevada, the team initially struggled because early stimulation results didn’t achieve the expected fracture connectivity. This meant we weren’t seeing the necessary flow rates to make the project viable. Instead of continuing with trial-and-error pumping strategies, we shifted toward a data-driven approach.
We integrated microseismic monitoring, well-test data, and geomechanical modeling to better understand the fracture network evolution. Using this data, I helped calibrate coupled reservoir–fracture models that revealed why stimulation fluid was not effectively propagating into the target zones. The analysis showed stress anisotropy was steering fractures away from our preferred direction.
Based on these insights, we adjusted the injection sequence, pressure schedules, and selected zones with a higher probability of fracture reactivation. As a result, we improved fracture connectivity, increased injectivity, and achieved sustainable flow rates that transformed the project from uncertain to technically successful.
10. What are the biggest obstacles technical, political, or operational that the geothermal industry refuses to talk about openly?
Political instability and inconsistent energy policy. Technically, we discuss challenges freely, but projects often fail due to sudden regulatory changes, permitting delays, or lack of financing frameworks. It’s the silent elephant in the room.
11. How do you balance the pressure for high energy output with the long-term sustainability of a reservoir?
By always planning for 20–30 years, not 2–3. It requires convincing stakeholders that moderate, steady production is better than chasing early peaks. Simulation helps us demonstrate the economic value of patience.
12. Supercritical geothermal resources are often called “the holy grail” of clean energy. How close are we really to unlocking their potential?
We’re closer than people think pilot wells in Iceland and Japan are already proving concepts but engineering materials, drilling technologies, and induced seismicity control are still hurdles. I believe within the next decade we’ll see the first commercial supercritical project.
13. Which emerging technology AI, digital twins, or advanced sensors do you think will revolutionize reservoir engineering, and why?
Digital twins integrated with real-time sensing will be the game changer. AI is powerful, but without live feedback, it risks being abstract. Digital twins will let us simulate and adjust operations on the fly, closing the gap between modeling and reality.
14. In your view, what is geothermal’s role in the next decade of the global energy transition?
Geothermal will be the quiet backbone less flashy than solar or wind, but crucial for baseload power and grid stability. As hydrogen and storage grow, geothermal will complement them, ensuring reliability.
15. If you had unlimited funding and freedom, what geothermal innovation would you pursue tomorrow?
A fully integrated fiber-optic sensing and AI-driven digital twin for EGS reservoirs. Real-time reservoir visibility would transform how we design and manage these systems.
16. Tell us about the most unexpected problem you’ve faced in a geothermal field and the creative solution you came up with.
In one project, scaling from silica precipitation clogged a well faster than anticipated. Instead of just chemical treatment, we designed a hybrid mechanical-chemical solution with pulsed injection cycles. It reduced downtime dramatically.
17. Collaboration can be tricky. Can you describe a time when you had to convince geologists, engineers, and operators to see your perspective on a project?
In a fractured reservoir project, geologists insisted that fractures connected to a nearby fault were beneficial. My simulation indicated a high risk of rapid pressure decline.
18. For aspiring geothermal engineers, what bold advice would you give something they won’t hear in textbooks?
Don’t just learn geothermal learn petroleum, mining, and even policy. The best geothermal engineers are multidisciplinary. And never forget: the reservoir is alive; treat it with respect.
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