T17 Hydrothermal Systems and Their Geologic Records

Sunday, 15 October 2023
8:00 AM - 12:00 PM
319

GEOTHERMAL CHARACTERISTICS OF SEDIMENTARY RESERVOIR IN THE FOLD-AND-THRUST BELT: INSIGHT FROM WESTERN TAIWAN

Paper number: T17-10
Program: Technical Sessions
Time: 10:10 AM – 10:25 AM

Authors

Abstract

Taiwan is situated at an active arc-continent collision zone and possesses numerous hot springs, making it a promising region for geothermal energy extraction. The Central Geological Survey of the Ministry of Economic Affairs, Taiwan, has undertaken several projects to harness this sustainable and renewable resource. Among the potential sites, the Guanziling area characterizes sedimentary mountain hills in the fold-and-thrust belt, and preliminary assessments have shown a high geothermal gradient. The previous petroleum activities have carried out various drilling and well logging by the CPC Corporation in Taiwan. The primary objective of this study is to construct the subsurface structures and utilize a combination of outcrop and subsurface data to identify hot sedimentary reservoirs.

In the outcrop analysis, we combined previously available data with new measurements in the field, mapping significant thrust faults, synclines and anticlines. Through lineament interpretation and fracture investigation at the surface and by comparing the spatial locations with the major geological structures in the region, the correlation between tectonics and fracture distribution can be revealed. Moreover, this approach enables us to evaluate how the fracture characteristics of the stratigraphic layers in the study area might impact the hydrogeology.

In three drillings data, critical fault-generated fractures with fluid veins indicate possible fault surfaces accompanied by fracture zones. The downhole dip meter has provided dipping changes, strongly suggesting the presence of detachment faults, which are possibly related to overpressure zones once causing mud loss and blowout while drilling. Porosity estimations derived from logging data have provided the characteristics of potential reservoirs within the sandstones, and the geothermal gradient reaches 40-45 ℃/km.

Two essential cross-section profiles have been established. The sedimentary reservoir with fault-related fractures plays a potential role in determining the geothermal resource in western Taiwan.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-396098

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