Next Article in Journal
A Multifunctional Isolated and Non-Isolated Dual Mode Converter for Renewable Energy Conversion Applications
Previous Article in Journal
A New Control-Oriented Semi-Empirical Approach to Predict Engine-Out NOx Emissions in a Euro VI 3.0 L Diesel Engine
Article Menu
Issue 12 (December) cover image

Export Article

Open AccessFeature PaperArticle
Energies 2017, 10(12), 1979; doi:10.3390/en10121979

Prospects for Assessing Enhanced Geothermal System (EGS) Basement Rock Flow Stimulation by Wellbore Temperature Data

1
Advanced Seismic Instrument & Research, 1311 Waterside, Dallas, TX 75218-4475, USA
2
St1 Deep Heat Oy, Purotie 1/PL 100, 00381 Helsinki, Finland
3
Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
*
Author to whom correspondence should be addressed.
Received: 16 September 2017 / Revised: 9 November 2017 / Accepted: 13 November 2017 / Published: 30 November 2017
(This article belongs to the Section Energy Sources)

Abstract

We use Matlab 3D finite element fluid flow/transport modelling to simulate localized wellbore temperature events of order 0.05–0.1 °C logged in Fennoscandia basement rock at ~1.5 km depths. The temperature events are approximated as steady-state heat transport due to fluid draining from the crust into the wellbore via naturally occurring fracture-connectivity structures. Flow simulation is based on the empirics of spatially-correlated fracture-connectivity fluid flow widely attested by well-log, well-core, and well-production data. Matching model wellbore-centric radial temperature profiles to a 2D analytic expression for steady-state radial heat transport with Peclet number Pe ≡ r0φv0/D (r0 = wellbore radius, v0 = Darcy velocity at r0, φ = ambient porosity, D = rock-water thermal diffusivity), gives Pe ~ 10–15 for fracture-connectivity flow intersecting the well, and Pe ~ 0 for ambient crust. Darcy flow for model Pe ~ 10 at radius ~10 m from the wellbore gives permeability estimate κ ~ 0.02 Darcy for flow driven by differential fluid pressure between least principal crustal stress pore pressure and hydrostatic wellbore pressure. Model temperature event flow permeability κm ~ 0.02 Darcy is related to well-core ambient permeability κ ~ 1 µDarcy by empirical poroperm relation κm ~ κ exp(αmφ) for φ ~ 0.01 and αm ~ 1000. Our modelling of OTN1 wellbore temperature events helps assess the prospect of reactivating fossilized fracture-connectivity flow for EGS permeability stimulation of basement rock. View Full-Text
Keywords: enhanced geothermal systems (EGS); crustal permeability; finite element flow modelling; crustal wellbore temperatures; wellbore injection; well logs; well core enhanced geothermal systems (EGS); crustal permeability; finite element flow modelling; crustal wellbore temperatures; wellbore injection; well logs; well core
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Leary, P.; Malin, P.; Saarno, T.; Kukkonen, I. Prospects for Assessing Enhanced Geothermal System (EGS) Basement Rock Flow Stimulation by Wellbore Temperature Data. Energies 2017, 10, 1979.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Energies EISSN 1996-1073 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top