Grantee Research Project Results

Final Report: An Innovative Design of Downhole In-Situ Power Generation: A Sustainable Manner of Geothermal Energy Utilization

EPA Grant Number: SU839292
Title: An Innovative Design of Downhole In-Situ Power Generation: A Sustainable Manner of Geothermal Energy Utilization
Investigators: Wu, Xingru , Ji, Guomin , Wang, Huiyu , Wang, Kai , Chen, Yuxuan
Institution: University of Oklahoma
EPA Project Officer: Page, Angela
Phase: I
Project Period: February 1, 2018 through January 31, 2019
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text | Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Air Quality , Sustainable and Healthy Communities

Objective:

Geothermal energy is a promising clean and renewable energy. Harnessing geothermal energy for power generation using oil wells features significant advantages over traditional geothermal wells, especially in reducing capital expenditure and operational risks. However, geothermal energy from oil well has gone waste mainly because its temperature is relatively lower than required for power generation through a power plant. The purpose of this project is to harvest the geothermal energy from oil wells and benefit people with clean resource in a cost-effective and sustainable manner, by the innovative design of downhole power generation in mature oil wells. Followed by the mathematical modelling and case studies to testify the potential of geothermal power generation using such design in oil wells.

Summary/Accomplishments (Outputs/Outcomes):

During phase I period, we accomplished the following tasks:

1) We designed a prototype of downhole geothermal power generation designs. An oil well with high water production rate is selected to implement downhole power generation. Detailed downhole and surface constructions are demonstrated graphically in technical papers. A lab scale design was demonstrated at National Sustainable Design Expo (NSDE) and showcased at the USA Science and Engineering Festival (USASEF) on April 7 and 8 at Washington Convention Center in Washington, DC.

2) We built the mathematical models to simulate the temperature distribution in the wellbore under variable oil well production conditions. Power generation efficiency could be obtained based on temperature distributions.

3) We conducted the sensitivity analysis to identify key parameters and studied the impacts of identified parameter on power generation.

4) Based on the sensitive study, we established section criteria of oil wells for geothermal production.

5) We did case studies and estimated the power generation efficiency to demonstrate the great potential of downhole power generation.

6) We set up laboratory model, ran lab tests for the downhole geothermal power generation, and experimentally verified the potential of this design.

Conclusions:

In phase I, our research led to the following conclusions:

1. Our demonstration of the design shows that downhole power generation is highly possible.

2. Applying the design on oil wells has tremendous benefits and advantages over alternatives. Compared to a geothermal well, existing wellbore and other infrastructures largely reduce capital expenditure. Compared to utilizing produced water at surface, this design improves thermal recovery efficiency by capturing in-situ heat before loss to formation.

3. The established model can capture the energy conversion efficiency accurately and is useful in guiding design improvement. The mathematical model could calculate the temperature distributions and power generation performances under various of production rates and enables the design improvements to maximum power generation.

4. This design can be also used in EGS wells and unconventional wells, which have a larger contact with reservoir formation to have better heat transfer and conversion efficiency.

Proposed Phase II Objectives and Strategies:

In the Phase II research, we will further improve the design prototype from Phase I by considering real engineering constraints. Our objectives are: 1) to design and select the geometry and material of thermoelectric generator to maximize the thermal-electricity conversion efficiency. 2) To study a new design for applications on horizontal wells. 3) to conduct larger-scale laboratory experiments to study the power generation efficiency in both the vertical well and horizontal well. 4) to optimize the downhole power generation design based on mathematical simulation and experimental results. 5) to work together with real engineering parameters and constraints to study its operational and economic viability.

This research will be conducted by a team of graduate students with diverse background in petroleum engineering, electrical engineering and mechanical engineering under professor’s supervision. Based on the archived outcomes in Phase I, students will conduct mathematical simulation and experimental investigation to improve the downhole power generation design. The team will keep incessancy communications with oilfield operators to optimize the parameters with the purpose to overcome field operational and economic constraints.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this project

Supplemental Keywords:

geothermal energy; geothermal power generation; thermoelectric technology; mature oil wells; thermal recovery; heat transfer

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.