GaS_GeoT: A computer program for an effective use of newly improved gas geothermometers in predicting reliable geothermal reservoir temperatures

Acevedo-Anicasio, A.; Santoyo, E.; Pérez-Zárate, D.; Pandarinath, Kailasa; Guevara, M.; Díaz-González, L.

doi:10.1186/s40517-020-00182-9

Geothermal Energy

Science – Society – Technology

Table 1 Updated compilation of gas geothermometers reported in the literature for determining geothermal reservoir temperatures

From: GaS_GeoT: A computer program for an effective use of newly improved gas geothermometers in predicting reliable geothermal reservoir temperatures

No	Gas geothermometer	Acronym	Gas-Mineral equilibria reactions	Gas concentration units	Geothermal reservoir-type^a	Calculation method	Temperature interval (°C)	References
1	CO₂-H₂S-CH₄-H₂	DP80	CaSO₄ + FeS₂ + 3H₂O + CO₂ ↔ CaCO₃ + 1/3Fe₃O₄ + 3H₂S + 7/3O₂ C + CO₂ + H₂ ↔ 2CH₄ + 2H₂O	% volume	LIQDR and VAPDR	Analytical	145–300	D’Amore and Panichi (1980)
2	H₂O-CO₂-CH₄-H₂	G80a	CO₂ + 4H₂ ↔ CH₄ + 2H₂O 2NH₃ ↔ N₂ + 3H₂	mmol/mol	LIQDR	Numerical^b	100–340	Giggenbach (1980)
3	NH₃-H₂-N₂	G80b	CO₂ + 4H₂ ↔ CH₄ + 2H₂O 2NH₃ ↔ N₂ + 3H₂	mmol/mol	LIQDR	Numerical^b	100–340	Giggenbach (1980)
4	CO₂-CH₄-H₂	ND84a	CO₂ + 4H₂ ↔ CH₄ + 2H₂O	Mole fraction	LIQDR	Analytical	150–350	Nehring and D’Amore (1984)
5	CO₂-H₂	ND84b	H₂ + 1/2O₂ ↔ H₂O C + O₂ ↔ CO₂	Mole fraction	LIQDR	Analytical	150–350	Nehring and D’Amore (1984)
6	CO₂-H₂S	ND84c	3FeS₂ + 2H₂ + 4H₂O ↔ Fe₃O4 + 6H₂S C + O₂ ↔ CO₂	Mole fraction	LIQDR	Analytical	150–350	Nehring and D’Amore (1984)
7	CO₂	AG85a	2clinozoisite + 2calcite + 3quartz + 2H₂O ↔ 3prehnite + 2CO₂	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
8	CO₂-H₂	AG85b	2clinozoisite + 2calcite + 3quartz + 2H₂O ↔ 3prehnite + 2CO₂ 4pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 2pyrite + 3H₂	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
9	CO₂-H₂	AG85c	2clinozoisite + 2calcite + 3quartz + 2H₂O ↔ 3prehnite + 2CO₂ 4pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 2pyrite + 3H₂	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
10	H₂	AG85d	4pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 2pyrite + 3H₂	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
11	H₂	AG85e	4pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 2pyrite + 3H₂	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
12	H₂S	AG85f	pyrite + pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 3H₂S	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
13	H₂S	AG85g	pyrite + pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 3H₂S	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
14	H₂S-H₂	AG85h	pyrite + pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 3H₂S 4pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 2pyrite + 3H₂	mmol/kg	LIQDR and VAPDR	Analytical	200–300	Arnórsson and Gunnlaugsson (1985)
15	CO₂-CH₄-CO	B85	CO₂ + H₂ ↔ CO + H₂O CH₄ + 3CO₂ ↔ 4CO + 2H₂O	Mole fraction	LIQDR and VAPDR	Numerical^b	n.r	Bertrami et al. (1985)
16	CO₂-N₂	A87a	n.a	mmol/kg	LIQDR	Analytical	200–300	Arnórsson (1987)
17	CO₂-N₂	A87b	n.a	mmol/kg	LIQDR	Analytical	200–300	Arnórsson (1987)
18	CO₂-H₂S-CH₄-H₂-CO	SD89	CO₂ + 4H₂ ↔ CH₄ + 2H₂O H₂ + 1/2O₂ ↔ H₂O H₂ + 1/2S₂ ↔ H₂S H₂ + CO₂ ↔ CO + H₂O 1/3Fe₃O₄ + S₂ ↔ FeS₂ + 2/3O₂	% mol	VAPDR	Numerical^b	140–370	Saracco and D’Amore (1989)
19	CO₂-CH₄	G91a	3CO₂ + CH₄ ↔ 4CO + 2H₂O	mmol/mol	LIQDR	Analytical	100–350	Giggenbach (1991)
20	H₂-Ar	G91b	2Fe₃O₄ + H₂O ↔ 3Fe₂O₃ + H₂ + O₂	mmol/mol	LIQDR	Analytical^b	100–350	Giggenbach (1991)
21	CO₂-Ar	G91c	n.a	mmol/mol	LIQDR	Analytical^b	100–350	Giggenbach (1991)
22	H₂-Ar	GG92a	FeS₂ + FeO + 2H₂O ↔ Fe₂O₃ + 2H₂S	mmol/mol	LIQDR	Analytical^b	100–350	Giggenbach and Glover (1992)
23	CO₂-CO	GG92b	FeS₂ + FeO + 2H₂O ↔ Fe₂O₃ + 2H₂S	mmol/mol	LIQDR	Analytical^b	100–350	Giggenbach and Glover (1992)
24	CO₂-H₂	K95a	Empirical geothermometer. Regression approach	% volume	LIQDR	Analytical	n.r	Koga et al. (1995)
25	CH₄-H₂	K95b	Empirical geothermometer. Regression approach	% volume	LIQDR	Analytical	n.r	Koga et al. (1995)
26	CO₂-H₂S	S96a	Empirical geothermometer. Multidimensional approach	% volume	LIQDR	Analytical	n.r	Supranto et al. (1996)
27	CO₂-H₂S-CH₄	S96b	Empirical geothermometer. Multidimensional approach	% volume	LIQDR	Analytical	n.r	Supranto et al. (1996)
28	CO₂	A98a	2clinozoisite + 2calcite + 3quartz + 2H₂O ↔ 3prehnite + 2CO₂	mmol/kg	LIQDR	Analytical	> 230	Arnórsson et al. (1998)
29	CO₂	A98b	2clinozoisite + 2calcite + 3quartz + 2H₂O ↔ 3prehnite + 2CO₂	mmol/kg	LIQDR	Analytical	> 230	Arnórsson et al. (1998)
30	H₂S	A98c	pyrite + pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 3H₂S	mmol/kg	LIQDR	Analytical	> 150	Arnórsson et al. (1998)
31	H₂	A98d	4pyrrhotite + 2prehnite + 2H₂O ↔ 2epidote + 2pyrite + 3H₂	mmol/kg	LIQDR	Analytical	> 150	Arnórsson et al. (1998)
32	CO₂-N₂	A98e	n.r	mmol/kg	LIQDR	Analytical	n.r	Arnórsson et al. (1998)
33	H₂S-Ar	A98f	n.r	mmol/kg	LIQDR	Analytical^b	n.r	Arnórsson et al. (1998)
34	H₂-Ar	A98g	n.r	mmol/kg	LIQDR	Analytical^b	n.r	Arnórsson et al. (1998)
35	H₂S	B06	2Fe₃O₄ + 12H₂S + CO₂ ↔ 6FeS₂ + 10H₂O + CH₄	% mol	LIQDR	Analytical	200–300	Blamey (2006)
36	CO₂-H₂-Ar	PC10a	2Fe₃O₄ + H₂O ↔ 3Fe₂O₃ + H₂ + O₂ 2H₂O + C ↔ 2H₂ + CO₂	% mol	LIQDR and VAPDR	Grid^b	100–350	Powell and Cumming (2010)
37	CO₂-CO-CH₄	PC10b	CacO₃ + K-mica ↔ CaAl₂-silciate + K-feldspar + CO₂ CO₂ + H₂O ↔ CO + H₂O 3CO₂ + CH₄ ↔ 4CO + 2H₂O	% mol	Liquid—and VAPDR	Grid^b	100–350	Powell and Cumming (2010)
38	CO₂-CH₄-H₂-H₂S	PC10c	CO₂ + 4H₂ ↔ CH₄ + 2H₂O 3FeS₂ + 2H₂ + 4H₂O ↔ Fe₃O₄ + 6H₂S FeS₂ + H₂ ↔ FeS + H₂S	% mol	LIQDR and VAPDR	Grid^b	100–350	Powell and Cumming (2010)
39	CO₂-CH₄-H₂	PC10d	CO₂ + 4H₂ ↔ CH₄ + 2H₂O CaCO₃ + K-mica ↔ CaAl₂-silicate + K-feldspar + CO₂	% mol	LIQDR and VAPDR	Grid^b	100–350	Powell and Cumming (2010)
40	CO₂-CH₄-H₂-H₂S	PC10e	CO₂ + 4H₂ ↔ CH₄ + 2H₂O 3FeS₂ + 2H₂ + 4H₂O ↔ Fe₃O₄ + 6H₂S FeS₂ + H₂ ↔ FeS + H₂S	% mol	LIQDR and VAPDR	Grid^b	200–350	Powell and Cumming (2010)
41	CO₂-H₂S-H₂	B16a	CO₂ + 4H₂ ↔ CH₄ + 2H₂O H₂ + 2H₂O + 3/2FeS₂ ↔ 3H₂S + 1/2Fe₃O₄	% volume	LIQDR	Numerical^b	125–350	Barragán et al. (2016)
42	CO₂-H₂S-H₂	B16b	CO₂ + 4H₂ ↔ CH₄ + 2H₂O 5/4H₂ + 3/4Fe₂O₃ + 3/2FeS₂ + 7/4H₂O ↔ 3H₂S + Fe₃O₄	% volume	LIQDR	Numerical^b	150–350	Barragán et al. (2016)
43	CO₂-H₂S-H₂	B16c	CO₂ + 4H₂ ↔ CH₄ + 2H₂O H₂ + FeS₂ ↔ H₂S + FeS	% volume	LIQDR	Numerical^b	100–350	Barragán et al. (2016)

^aType of geothermal reservoir used to calibrate the gas geothermometers
^bGas geothermometers that were not considered in this work
n.r. = not reported; n.a. = not available. Analytical method refers to a gas geothermometer that provides a direct mathematical function for the calculation of the reservoir temperatures, i.e., BHT = f(gas concentration); whereas Numerical method refers to a more complex function that correlate multiple variables (i.e., gas concentration, pressure, the fraction of water, temperature, among others); Grid geothermometric method refers to a gas geothermometer that provides a complex grid-numerical algorithm for the estimation of temperatures and other key parameters of the reservoir (i.e., steam fraction, distribution coefficients, and the steam/gas ratio)

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