Estimating the Permeability-Depth Relation of Slate Formation for Geothermal Project

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985891%3A_____%2F25%3A00638931" target="_blank" >RIV/67985891:_____/25:00638931 - isvavai.cz</a>

Výsledek na webu

<a href="http://hhttps://doi.org/10.1007/s00603-025-04590-w" target="_blank" >http://hhttps://doi.org/10.1007/s00603-025-04590-w</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s00603-025-04590-w" target="_blank" >10.1007/s00603-025-04590-w</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Estimating the Permeability-Depth Relation of Slate Formation for Geothermal Project

Popis výsledku v původním jazyce

Slate formation is one of the potential geothermal sites in Taiwan. However, the fluid flow capability of slate formations has not been well investigated internationally. This study proposes a procedure to evaluate the permeability-depth relationship in slate formations. We used slate samples from the Hungyeh Formation in Taiwan to measure the permeability (k) of intact slate and the hydraulic aperture (e) of natural/artificial tensile fractures along the foliation, under confining pressures up to 60 MPa (similar to 3500 m depth). Stress-dependent models of permeability and hydraulic aperture were developed using a power law and an exponential function, respectively. The equivalent vertical permeability (k(v,eq)) of slate formation with fractures is calculated using Snow's model, which considers the aperture (e) and spacing (s) of vertical fractures subparallel to the foliation. The matrix permeability (< 0.001 mD) decreases with increasing depth. The k(v,eq) of the slate formation, contributed by fractures along the vertical foliation (assuming s = 1.0 m), is several tens of times greater than the intact slate permeability. Within the target depth range of 1500-1700 m, and assuming s = 0.2 m generated by hydraulic fracturing (HF), the mean k(v,eq) ranges from 3.0 x 10(-2) to 2.3 x 10(-2) mD under an injection pressure of 10 MPa. To enhance energy generation efficiency in slate formations, improving HF design to create denser fractures and identify fracture zones, is suggested. The proposed approach is a simple and feasible way to evaluate the permeability-depth relation of reservoirs for geothermal projects before the detailed site investigation program.

Název v anglickém jazyce

Estimating the Permeability-Depth Relation of Slate Formation for Geothermal Project

Popis výsledku anglicky

Slate formation is one of the potential geothermal sites in Taiwan. However, the fluid flow capability of slate formations has not been well investigated internationally. This study proposes a procedure to evaluate the permeability-depth relationship in slate formations. We used slate samples from the Hungyeh Formation in Taiwan to measure the permeability (k) of intact slate and the hydraulic aperture (e) of natural/artificial tensile fractures along the foliation, under confining pressures up to 60 MPa (similar to 3500 m depth). Stress-dependent models of permeability and hydraulic aperture were developed using a power law and an exponential function, respectively. The equivalent vertical permeability (k(v,eq)) of slate formation with fractures is calculated using Snow's model, which considers the aperture (e) and spacing (s) of vertical fractures subparallel to the foliation. The matrix permeability (< 0.001 mD) decreases with increasing depth. The k(v,eq) of the slate formation, contributed by fractures along the vertical foliation (assuming s = 1.0 m), is several tens of times greater than the intact slate permeability. Within the target depth range of 1500-1700 m, and assuming s = 0.2 m generated by hydraulic fracturing (HF), the mean k(v,eq) ranges from 3.0 x 10(-2) to 2.3 x 10(-2) mD under an injection pressure of 10 MPa. To enhance energy generation efficiency in slate formations, improving HF design to create denser fractures and identify fracture zones, is suggested. The proposed approach is a simple and feasible way to evaluate the permeability-depth relation of reservoirs for geothermal projects before the detailed site investigation program.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20701 - Environmental and geological engineering, geotechnics

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Rock Mechanics and Rock Engineering

ISSN

0723-2632

e-ISSN

1434-453X

Svazek periodika

58

Číslo periodika v rámci svazku

8

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

16

Strana od-do

8867-8882

Kód UT WoS článku

001480787100001

EID výsledku v databázi Scopus

2-s2.0-105004054045