Stress sensitivity of porosity and permeability under varying hydrostatic stress conditions for different carbonate rock types of the geothermal Malm reservoir in Southern Germany

Geothermal Energy

Science – Society – Technology

Table 3 Geomechanical characteristics of the investigated rock samples from dynamic and static tests

Sample	Lithology	\({\varPhi }^{i}\)	\({v}_{\mathrm{p}}\)	\({v}_{\mathrm{s}}\)	\({\sigma }_{\mathrm{s}}\)	\(E\)	\({E}^{\mathrm{dyn}}\)	\({K}^{\mathrm{dyn}}\)	\({G}^{\mathrm{dyn}}\)	\({\nu }^{\mathrm{dyn}}\)
Sample	Lithology	%	m s⁻¹		MPa	GPa				–
L1	Limestone	13.0	4777	2083	60.4	31.6	27.9	39.8	10.1	0.38
L2	Limestone	14.5	5001	2737	49.2	26.8	34.6	34.4	17.2	0.29
L3	Limestone	18.1	3030	1780	49.4	16.0	16.8	10.1	6.9	0.22
L4	Limestone	12.7	3855	2028	51.4	29.3	24.9	20.4	20.4	0.30
L5	Limestone	15.8	4983	2608	63.6	27.8	30.2	22.4	11.8	0.28
dL1	Dol. limestone	13.0	3052	1897	58.9	24.5	20.1	10.6	8.5	0.18
dL2	Dol. limestone	15.0	3098	1556	50.2	24.9	18.5	22.0	6.8	0.36
D1	Dolostone	14.9	4367	2618	86.7	33.9	39.4	23.5	16.2	0.22
D2	Dolostone	9.8	5342	2955	94.9	48.2	54.3	41.3	21.2	0.28
D3	Dolostone	8.9	4496	2093	68.5	32.2	30.4	36.7	11.2	0.36
D4	Dolostone	8.2	4625	2620	112.0	51.5	44.0	30.8	17.4	0.26
D5	Dolostone	2.3	5317	3343	90.5	41.5	68.7	35.1	29.3	0.17
D6	Dolostone	9.2	5597	2926	77.0	40.4	53.8	47.7	20.5	0.31
D7	Dolostone	4.0	6014	3414	125.7	53.8	79.0	55.8	31.2	0.26
D8	Dolostone	3.7	5850	3177	106.2	51.0	49.2	30.6	20.0	0.23

Data for geomechanical parameters were taken from Potten (2020). \({\varPhi }^{i}\) initial porosity, \({v}_{\mathrm{p}}\) compression wave, \({v}_{\mathrm{p}}\) shear wave, \({\sigma }_{\mathrm{s}}\) rock strength, \(E\) and \({E}^{\mathrm{dyn}}\) static and dynamic Young’s modulus, \({K}^{\mathrm{dyn}}\) dynamic bulk modulus, \({G}^{\mathrm{dyn}}\) dynamic shear modulus, \({\nu }^{\mathrm{dyn}}\) dynamic Poisson’s ratio