In:
Energy Exploration & Exploitation, SAGE Publications, Vol. 37, No. 2 ( 2019-03), p. 736-755
Kurzfassung:
In the study, we analyzed the hot dry rock geothermal field of the Guide Basin in Qinghai Province, China. We used T2Well software—a coupled wellbore–reservoir simulator—to build a “wellbore–reservoir” coupled model with a “three-spot” well pattern (one injection and two production wells). We simulated several fixed flow rate cases in which water or CO 2 is injected. The objectives of our present work are (1) to investigate the fluid flow and thermal processes of water circulating at well bottoms, wellbores, and wellheads; (2) to identify the changing parameters at all physical fields; (3) to understand the influence of injection rates on heat extraction; and (4) to measure the maximum heat extraction capacity of the Guide area. Water extracts more heat than CO 2 at the same flow rate. However, water consumes more pressure in reservoir, and its pressure decreases more quickly as the flow rate increases. In contrast, CO 2 is in a sense a better working fluid. CO 2 consumes less pressure when it flows and can circulate automatically due to the siphon phenomenon. In this way, a lower injection pressure is required in a higher CO 2 flow rate case. The density of CO 2 is sensitive to both temperature and pressure and vice versa. Inside a wellbore, such interactions are extremely complicated. When the fluid rate is slow, a system could operate for 30 years and remain stable, and there is only a small decrease in temperature. However, with higher flow rate scenarios—namely 50, 75, and 100 kg/s—the reservoir will exhibit greater heat loss. The reservoir’s production temperature and extraction efficiency will drop dramatically. Therefore, for the Guide area, if a “three-spot” well pattern is used for geothermal extraction either with water or CO 2 as the working fluid, the most appropriate flow rate is 50 kg/s.
Materialart:
Online-Ressource
ISSN:
0144-5987
,
2048-4054
DOI:
10.1177/0144598718795492
Sprache:
Englisch
Verlag:
SAGE Publications
Publikationsdatum:
2019
ZDB Id:
2026571-2
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