Page 142 - Reservoir Geomechanics

125 Rock failure in compression, tension and shear

a. 410 Pressure 60
Average monthly pressure at bottom of arsenal well (in bars) 390 40 Number of Denver earthquakes, per month, of magnitude 1.5 or greater
400

380
370
360

350
20
340
330
320 Quakes
1962 1963 1964 1965 1966 1967 1968

b. 200 5000

150 4000
Number of earthquakes 100 3000 Monthly downhole pressure, psi

50 2000

0 1000
O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M
1969 1970 1971 1972 1973 1974
Fluid Fluid Fluid
injection withdrawal injection
Figure 4.22. (a) Correlation between downhole pressure and earthquake occurrence during periods
of fluid injection and seismicity at the Rocky Mountain Arsenal. Modified from Healy, Rubey et al.
(1968). (b) Correlation between downhole pressure and earthquake occurrence triggered by fluid
injection at the Rangely oil field in Colorado. After Raleigh, Healy et al.(1976).