Geothermal stimulation

Soviet researchers indicated that thermal stimulation from above the ground was not economically viable. Trofimuk et al. (1982) suggested alternatives of pressure reduction, inhibitor injection, geothermal stimulation, or in situ combustion techniques. Recovery techniques modeled in the Western Hemisphere were by either pressure reduction or thermal stimulation. The first of these was by McGuire (1982), followed by Holder et al. (1984a), Burshears et al. (1986), and workers in the CSM laboratory (Selim and Sloan, 1985, 1987, 1989 Yousif et al., 1988, 1990). 

Crema, S.C. Aim, R.R. "Foaming of Anhydrous Methanol for Well Stimulation", SPE paper 13565, 1985 International Symposium on Oilfield and Geothermal Chemistry, Phoenix, April 9-11. 

Clementz, D.M., Patterson, D.E., Aseltine, R.J., and Young, R.E. "Stimulation of Water Injection Wells in the Los Angeles Basin Using Sodium Hypochlorite and Mineral Acids," SPE paper 10624, 1982 SPE International Symposium on Oilfield and Geothermal Chemistry, Dallas, January 25-27. 

Baldi, P., Bertini, G., Calore, C., Capetti, G., Cataldi, C., Celati, R. Squarci, P. 1980. Selection of dry wells in Tuscani for stimulation tests. In Proceedings 2nd DOE-ENEL Workshop for Cooperative Research in Geothermal Energy, Berkeley, 98-115. 

Bruel, D. 1995. Heat extraction modeling from forced fluid flow through stimulated fractures rock masses Applications to the Rosemanowes hot-dry rock reservoir. Geothermics, 24, 361-374. 

Evanoff, J., Yeager, V. Spielman, P. 1995. Stimulation and damage removal of calcium carbonate scaling in geothermal wells A case study. In Proceedings World Geothermal Congress, Florence, 18-31 May, 2481-2486. 

This project is of interest for several reasons, but primarily because the deep fluid is used as a closed loop, avoiding surface storage of brines, and because the seismicity induced by stimulation of the reservoir is continually watched in order to limit the risks. The Soultz-sous-Forets geothermal site could be a... 

The depths of the pressure stimulation and thermal stimulation experiments are superimposed on the methane phase equilibria—geothermal gradient diagram shown in Figure 7.35 (Wright et al., 2005). Without a BSR, the geothermal gradient... 

Figure 7.35 Mallik 2002 geothermal gradient and hydrate stability curve for pure water and water containing 40 ppt salt. Note the depths of the thermal stimulation test and the six pressure stimulation (MCT) tests. (From Wright, J.F., et al., in Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program, Mackenzie Delta, Northwest Territories, Canada, Geological Survey of Canada Bulletin 585, including CD (2005). With permission.)...

Second, interest in geothermal energy has stimulated research into various aqueous geothermometers . One which has been used with success, based ultimately on feldspar equilibria, is the Ca/Na geothermometer. Using the data of Helgeson (1972, fig. 9), or the empirical formula of Fournier and Trusdell (1973), and the ion ratios of Edwards brine from Fig. 2., a temperature of 200°C is calculated. This is a reasonable temperature for updip Jurassic salt in the Gulf of Mexico today (6000 m x 30°C/km). 

A Comprehensive understanding of the fracture distribution and hydro-geomechanical processes occurring during hydraulic stimulation is essential in both conventional and Hot Dry Rock (HDR)/ Hot Wet Rock (HWR) geothermal development. Some of this information can be obtained from well logs such as flow, temperature, pressure, BHTV, FMI, etc. However, they only provide restricted information near the well. 

HDR/HWR geothermal development. These techniques have been applied to the microseismic data set obtained during the hydraulic stimulation at Soultz HDR field, France, in 1993. Detailed seismic structure of a seismic line, which was growing linearly at the early stage of the stimulation, has been analysed. It is estimated that this structure shows enhanced permeable paths and consist of sub parallel microstructures, which are oriented to the directions most easy to slip by the stimulation. 

Evans, K. F. (2000). The effect of the 1993 stimulations of well GPKl at Soultz on the surrounding rock mass Evidence for the existence of a connected network of permeable fractures., Proc. World Geothermal Congress 2000, Vol. 6, 3695-3670. 

Since the fluid velocity within the geothermal reservoirs created in the fractured rock can be relatively high and the characteristic sizes of the solid blocks of the rock, which constitute the fissured reservoir media, are relatively large, the high mean values of heat flow rates are typically attained within the stimulated region. In this situation the effect of thermal dispersion is an important factor that should be included into the mathematical model of the heat transport within the natural or artificially developed fissured geothermal reservoirs. Employing different... 

In this paper, we suggest a method for estimation of pore-pressure during hydraulic stimulation of geothermal reservoir by using the induced microseismic multiplets. The results of the application to the microseismic events at Soultz field are demonstrated showing the feasibility of the method. 

Hydrogen sulflde abatement wastes from geothermal energy production Well completion, treatment, and stimulation fluids... 

H2S, together with COS, is another principal atmospheric corrosion stimulant. It is emitted both from natural biological sources (e.g., volcanoes, moss, or swamp areas) and from anthropogenic sources (e.g., pulp and paper industries, catalyst converters in motor vehicles, sewage plants, garbage dumps, animal shelters, and geothermal power plants). H2S can react with OH- to form SO2 according to [15] ... 

Water-wetting surfactants, necessary in oil well stimulation, are not needed in geothermal wells because of the absence of hydrocarbons. Suspending agents (nonemulsifier surfactants) are also not needed, although they are often included in geothermal well stimulation job proposals. A clay stabilizer is not needed. 

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