Subsurface Engineering for Sustainable Energy

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New Faculty and Course Ofer Students Exciting Versatility

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Dr. Rita Esuru Okoroafor, assistant professor and faculty member in the Harold Vance Department of Petroleum Engineering at Texas A&M University, will co-instruct the department’s newest course this fall: PETE 489, Carbon Capture Utilization and Storage. The course represents an exciting direction for the department’s undergraduate curriculum.

Okoroafor and Dr. Maria Barrufet, professor and Baker Hughes Endowed Chair in petroleum engineering and affiliated faculty in chemical engineering, will collaborate on teaching the material since it requires interdisciplinary instruction.

The following is an interview with Okoroafor, who shared both her experiences and her hopes for petroleum engineering students.

Q: What is your background?

A: I am a petroleum engineer by training and have spent approximately 15 years working in the oil and gas industry, primarily with SLB (formerly Schlumberger). However, I decided to expand my knowledge on energy resources and obtained a Ph.D. in geothermal energy from the School of Earth, Energy and Environmental Sciences at Stanford University.

Q: Is geothermal energy relatable to petroleum engineering?

A: I started without knowing anything about geothermal energy. But as I progressed in my research, I found many of the skills I had as a petroleum engineer were what I was using in geothermal research, so yes, geothermal energy is relatable to petroleum engineering in many ways. After I finished my Ph.D., I spent one year at Stanford University as a postdoc and was assigned to projects in carbon capture, utilization and storage, and underground hydrogen storage. Those were things I didn’t really have knowledge about, but again my petroleum engineering skills fast-tracked most of my understanding of those projects.

That made me realize that we should not be afraid of the energy transition or the evolving energy mix because, as petroleum engineers, we have a role in each of these areas. Our skills are relevant in a vast majority of fields, including carbon capture, utilization and storage, geothermal energy and even offshore wind, solar energy and photoelectric membranes. We have a variety of skills that are transferable.

Q: How do you hope to impact the students at Texas A&M?

A: My role in the oil and gas industry was both technical and non-technical. In addition to my core petroleum engineering technical roles, my experience includes roles like project management, sales management and product development. Those experiences help me mentor and coach as I engage with students. I don’t just offer technical advice. I let them know the non-technical skills they pick up here, such as critical thinking, problem-solving, perseverance and dedication, also apply to many things they do in life.

Q: What is it like being in the petroleum engineering department at Texas A&M?

A: I love the opportunity to share knowledge. I love that when I wake up in the morning and have a question I want to answer, I can look for ways of answering those questions through research. And I’m grateful for the support and mentorship I receive here. I also want to give support and mentoring to others, both in the department and outside it, and the department offers me the opportunity to give a lot of myself.

Q: What do you teach?

A: I’m currently teaching an undergraduate course on formation evaluation. Teaching formation evaluation comes from my experience as a borehole reservoir engineer at SLB. We looked at petrophysical data and combined it with reservoir data to gain a better understanding of formations.

Last semester, I taught a graduate course on subsurface engineering for sustainable energy, where we take the skills we already have in subsurface — such as fluid flow in porous media — and bring them in to understand both the subsurface behavior of geothermal reservoirs and the storage of carbon and energy in geological media. I plan to repeat the course this fall.

Q: Can you explain more about the new undergraduate course?

A: A lot of focus right now is on combining carbon capture — that is, capturing carbon dioxide (CO2) emissions from industrial plants, oil and gas operations, or any industry that releases carbon — and storing that carbon. The new course is for seniors because they are at a point where they have learned enough about petroleum engineering to understand carbon storage.

We will introduce students to where emissions come from and how to quantify them. We will explore the thermodynamics of CO2 and how we compress, transport, utilize and store it. We will look at different storage mechanisms and delve into geological media storage because we feel it has the best capacity to store CO2 in large quantities. We will also expose the students to regulations, policies and incentives and how they evolve. We will help them understand the economics of carbon capture storage (CCS) projects, what they have been, what they look like now with new policies and where they should be going.

Q: What do you hope the students will gain?

A: We want our students to be versatile, knowing what they should know as petroleum engineers yet being able to fit into these new areas related to decarbonization. Let’s say an oil and gas company wants to hire our students and has a department that deals with storage. Our students can fit into such a department. If our students want to perform CCS research or start a decarbonization company, they will be able to because they have that fundamental knowledge. We want to equip them with confidence.

Carbon Dioxide Proving Its Worth in Green Energy Application

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What if we could do more with carbon dioxide (CO2) than lock it safely away in the subsurface? What if this greenhouse gas could instead be used in geothermal energy and power millions of homes worldwide?

Touka Elsayed, a master’s student in the Harold Vance Department of Petroleum Engineering at Texas A&M University, is winning attention by testing this concept in her research of geothermal reservoirs and CO2 properties. Her work involves modeling geothermal systems’ size and heat transfer abilities, investigating how well CO2 would work in such systems, and analyzing the economics and technology involved.

“It’s called CO2 plume geothermal energy,” said Elsayed. “This innovation aims to harness the potential of carbon dioxide to generate geothermal energy while substantially contributing to sustainability and benefiting the environment.”

A new energy approach

Traditionally, geothermal energy can be sourced from natural reservoirs or dry rock. Natural reservoirs are usually associated with hot water or steam from beneath the geysers and other hydrothermal vents to power turbines for energy. Dry rock provides geothermal energy when drilling operations reach hot rock, and water is injected to extract heat from the rock through hot water or steam.

Elsayed is investigating a newer approach, called CO2 plume geothermal energy (CPG) systems, where carbon dioxide could be injected into hot porous reservoirs instead of water. Her modeling studies showed this approach allows for a more efficient heat extraction because CO2 has superior flow properties than water, such as being more buoyant, and thus would require less energy to make it flow out. Results revealed CPG also offers a method for carbon sequestration, providing a dual benefit of renewable energy generation and greenhouse gas reduction.

This innovation aims to harness the potential of carbon dioxide to generate geothermal energy while substantially contributing to sustainability and benefiting the environment.

Touka Elsayed

Using CO2 safely

Thanks to previous carbon capture utilization and storage (CCUS) studies, Elsayed already knew storing CO2 in the subsurface must meet specific standards to be safe and effective:

  • One or more caprocks or layers of impermeable rock are needed to keep the CO2 from permeating back to the surface.
  • The injection sites must be deep enough so that pressures and temperatures keep the gas dense or compact, so it takes up much less space than at sea level or above.
  • Porous sedimentary rock layers or a saline aquifer must be below the caprock to house the injected gas.

Elsayed also needed the right conditions for CO2 to be hot enough for heat transfer in a CPG yet flow predictably for safe handling. The gas is usually supercritical at a depth of 800 meters (around 2,600 feet) where subsurface temperatures are above 31.1°C (88°F) and pressures are about 73 atmospheres. Her simulations revealed that up to 15% of the CO2 would chemically bond with salt water in an aquifer and with the porous sedimentary rock formations, which secures the CO2 permanently and creates a need for more gas injections to continue the energy production.

Gaining recognition

Elsayed created a poster of her results and presented it at the Geothermal Rising Conference in October 2023. She won first place out of a competition of 40 posters. She was among five graduate students awarded the prestigious Geothermal Rising Marcelo Lippmann 2023 Graduate Scholarship and the only master’s student.

“Knowing that a respected organization like Geothermal Rising recognized my work and believed in my potential was truly inspiring,” said Elsayed. “I felt an increased awareness about my topic, which was new to everyone there. Several companies were curious to know more.”

I always believe the journey of being an engineering student is not just about earning a degree. It is about shaping your mindset and skills to become a lifelong problem solver.

Touka Elsayed

In the same conference, Elsayed presented a paper she co-authored with fellow graduate student Ahmed Merzoug and their advisor, Dr. Rita Okoroafor. The paper, “Numerical Investigation of the Effect of Fracture Aperture Anisotropy on Thermal Breakthrough Using THM Modeling,” explained how fracture surfaces can impact the long-term performance of geothermal energy from hot, dry rocks.

Factoring techno economics

Elsayed is currently performing technical and economic feasibility studies, or techno economics, of CPG systems paired with a carbon capture project.

Some of the many factors she must estimate to prove the system is feasible are:

  • The different capturing technologies and the cost estimation for each.
  • The cost analysis for different components of a full CCUS value chain.
  • The heat energy gained and available to sell to utilities over the lifespan of a CPG system.

Elsayed hails from Egypt and said she has enjoyed her education at Texas A&M because students are so welcoming. While her dream job would be working as a top-tier oil and gas company strategic manager, she also wants to help facilitate the energy and sustainability transitions needed globally.

“We need to be open to new ideas and technologies,” said Elsayed. “I always believe the journey of being an engineering student is not just about earning a degree. It is about shaping your mindset and skills to become a lifelong problem solver. Everyone has the potential to make a significant difference.”

Education for a Geologically-Energized Future

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Researchers are looking to geological hydrogen as a clean and cost-effective alternative energy source.

As geological hydrogen use grows, so will the demand for a skilled workforce. To help address this need, The Association of Geological Hydrogen (AGH), a non-profit organization, is negotiating up to $300,000 in funding from the U.S. Department of Energy (DOE) to create an educational framework to foster a new geological hydrogen workforce pipeline in the U.S. Researchers will establish new industry-university-national labs partnerships to facilitate internships, provide career mentorship and coaching opportunities.

Dr. Esuru Rita Okoroafor, a Chevron Faculty Fellow and assistant professor in the Harold Vance Department of Petroleum Engineering, will support this project by developing a textbook, with several chapters dedicated to geological hydrogen. She will also lead efforts in mentorship and coaching sessions focused on exposing students to geological hydrogen. The project also aims to create a certificate program covering the basics of geological hydrogen.

“Ultimately, this project will provide a foundational knowledge that allows someone to apply any skills they have to the field of geological hydrogen,” said Okoroafor. “If someone is a geologist, for instance, but has taken the certificate program, it allows them to apply their geology towards geologic hydrogen. The same can be said for engineering or any other field.”

By introducing an educational framework at the high school level, students will develop field-specific skills in college or trade school and apply them to the geological hydrogen workforce.

“We want students to see geological hydrogen not just as a concept, but as a dynamic and exciting career path,” said Okoroafor. “Building enthusiasm today is what will drive the growth of tomorrow’s geological hydrogen workforce.”

Collaborating with Okoroafor on this project is Dr. Qingwang (Kevin) Yuan, the Lead PI of this project, the president of AGH, and an assistant professor in the Bob L. Herd Department of Petroleum Engineering at Texas Tech University.

This grant is part of the DOE’s Clean Energy Careers for All program, which supports workforce development that promotes STEM education and exposure to clean energy career options. AGH was one of seven non-profit organizations selected to receive funding as part of this initiative.

2025 Student Research Week 1st Place Winner (PhD Category)

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What if porous rocks held the key to clean hydrogen storage? At Texas A&M University, graduate students are answering questions that could redefine the future of energy.

For over thirty years, Texas A&M has held Student Research Week (SRW) annually to recognize and celebrate the impactful research students are conducting. As the largest student-run research symposium in the country, SRW is where innovation and excellence collide. Student research in the classroom will translate to cutting-edge industry solutions and have significant impacts.

For 2025, two graduate students from the Harold Vance Department of Petroleum Engineering earned first place in their respective categories. One of them was Henry Galvis Silva, a Ph.D. candidate and member of the Subsurface Engineering for Sustainable Energy Research Group.

Galvis’ presentation, “Subsurface Porous Media Potential for Engineering Hydrogen Storage and Generation Systems,” focused on the importance of porous rocks for hydrogen systems, specifically for safely storing hydrogen underground and collecting natural hydrogen that forms through serpentinization.

By integrating subsurface modeling with lab experiments, Galvis’ research assessed hydrogen generation and storage potential in porous rocks, as well as cap rock integrity.

These findings are relevant because they are a key step toward unlocking the hidden value of the subsurface for future hydrogen resource development. By understanding how hydrogen can be generated, stored, and sealed underground, we’re helping lay the groundwork for the global transition to sustainable energy.

Henry Galvis Silva

Research on Geological Hydrogen Receives Funding from U.S. Department of Energy

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Dr. Rita Esuru Okoroafor was selected to receive $1.5 million in funding from the U.S. Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) to study geologic hydrogen.

The funding is part of ARPA-E’s Exploratory Topics related to geologic hydrogen, which aim to explore early-stage research and development to advance low-cost, low-emissions hydrogen. This is the first time the Harold Vance Department of Petroleum Engineering is receiving funding from ARPA-E.

Okoroafor will lead a multi-institutional team, including the New Jersey Institute of Technology and Louisiana State University, in a two-year investigation. She aims to model the best, most efficient methods for producing hydrogen from subsurface ultramafic rocks.

“Low-cost, low-emission hydrogen production could revolutionize the energy landscape,” Okoroafor said. “This research aims to make that vision a reality.”

Biofilms to Barriers: How Microbes Can Shape Hydrogen Storage

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As researchers pursue more efficient and scalable energy-storage solutions, the subsurface is emerging as a promising frontier. From storing next-generation fuels like hydrogen to sequestering carbon emissions, Texas A&M faculty and students are investigating options that could be kept safely underground.

Two independent teams, including researchers from the Harold Vance Department of Petroleum Engineering recently received seed funding through Texas A&M’s Targeted Proposal Teams (TPT) program to accelerate their early-stage work. Launched in 2024, TPT supports interdisciplinary projects that address urgent problems in areas such as energy, health and quality of life, food and resource security, and national resilience.

One of the funded projects, “Quantifying the Impact of Biofilm Formation on Underground Hydrogen Storage,” is led by Dr. Rita Esuru Okoroafor from the Harold Vance Department of Petroleum Engineering and Dr. Yinou Yao from the Zachary Department of Civil and Environmental Engineering.

As hydrogen gains traction as a low-carbon energy carrier, storing large volumes safely and recoverably becomes essential and the underground offers a scalable option. Injecting hydrogen into pore spaces underground raises distinctive scientific questions, including containment, contamination, and an often-overlooked biological factor: subsurface microbes.

“Some microbes are known to be capable of consuming hydrogen as food,” Dr. Okoroafor said. When these microbes feed on hydrogen, they can form biofilms that occupy pore space. However, there is no understanding to show if these biofilms keep the hydrogen in place or interferes with storage and recovery. Hence, the motivation of our project. 

Realizing that, depending on where biofilms form, the microbes could play opposite roles, this experimental project uses carefully selected microbes under tightly controlled temperatures and hydrogen injection rates to replicate subsurface conditions.  For instance, biofilms can help to reinforce seal rocks that prevent leakage or clog reservoir rock pores thereby reducing hydrogen injectivity and recoverability. We plan to analyze our experimental results in Fall 2025 to clarify those tradeoffs and guide design strategies for safe, long-term underground hydrogen storage.

Advancing Energy Through Research in Porous Media

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Dr. Rita Esuru Okoroafor is developing new best practices and frameworks that support alternative energy storage technologies through her research in porous media.

Porous media refers to natural or engineered materials, such as rock formations or soil, that contain interconnected pores or void spaces. These pores allow fluids to move through the material. In subsurface engineering, porous media is important in processes like groundwater flow, oil and gas extraction, and other processes such as carbon storage, geothermal energy production, and hydrogen storage.  

For her research and dedication to this field of study, Dr. Rita Esuru Okoroafor, assistant professor and Chevron Corporation Faculty Fellow in the Harold Vance Department of Petroleum Engineering, is the recipient of the Rien van Genuchten Early-Career Award of Porous Media for a Green World.   

According to Okoroafor, she integrates geochemistry, geomechanics, and reservoir engineering with laboratory experiments and advanced simulations to improve understanding of these fluid-rock interactions, enhance hydrogen storage efficiency, optimize geothermal reservoir performance, and improve the long-term security of CO₂ storage. Her research also explores the impact of these subsurface technologies on communities, ensuring there is no short-term or long-term impact on people and society.  

“This synergy between experiments and simulation has equipped me with the ability to understand challenges such as rock alterations, seal integrity, and fluid transport in geothermal systems, hydrogen storage and carbon sequestration, enabling me to make significant strides in advancing subsurface sustainable energy solutions,” said Okoroafor.    

As the honoree, Okoroafor will attend the Interpore Conference, which will allow her to expand and strengthen her research collaborations with global experts and present her findings at the conference. The award will also help her continue discovering best practices, regulatory frameworks and risk mitigation strategies in porous media.    

“Receiving the Rien van Genuchten Early-Career Award is indeed an honor and a validation of the hard work my team and I have put into advancing subsurface energy research,” said Okoroafor. “It is gratifying to have my contributions recognized early in my career, and it reinforces my commitment to pushing the boundaries of knowledge in porous media science and engineering for a sustainable future.”  

Additionally, Okorafor was recognized as one of the top 10 pioneering women leaders for the future of hydrogen by Women World Magazine, further showcasing her commitment and excellence in sustainable and renewable energy research.  

Her successes have come through collaboration with students and faculty, including her former students Axel Indro, Deena Tayyib, Ahmed Bin Abed, Oluwakemi Olofinnika, Yuezhou Kang, and Aidan Watson, and current students Henry Galvis, Lokesh Kumar Sekar, Touka Elsayed, and Vida Martey-Korley. Okoroafor continues working closely with her colleague, Dr. Hamidreza Samouei, from the Department of Petroleum Engineering. Okoroafor has also received support for her research from the following: Texas A&M’s Energy Institute under the leadership of Dr. Efstratios Pistikopoulos; WD Von Gonten Labs; and Dr. Raymundo Case of the National Corrosion and Materials Reliability Lab. 

Congratulations to Oluwakemi Olofinnika

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Graduate student Oluwakemi Olofinnika was recently awarded the Texas A&M Energy Institute scholarship.

The Energy Institute scholarship is a prestigious program that recognizes outstanding achievements and research in the fields of energy digitization, resilient energy, geothermal energy, carbon capture, utilization and storage, and energy transition.

Olofinnika’s research focuses on designing CO2-enhanced oil recovery and carbon sequestration strategies to improve low-carbon and sustainable energy delivery. Dr. Rita Esuru Okoroafor is Olofinnika’s advisor and research supervisor.

“I am humbled and honored to have been chosen as one of five recipients of this scholarship,” Olofinnika said. “I believe that this achievement aligns well with the petroleum engineering department’s values and goals and sheds a positive light on the department’s commitment to low carbon and sustainable energy development.”

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