Although explosives, acidizing and other methods have long been used
in oil and gas well treatment, high pressure hydraulic stimulation was
first time successfully intro-duced in the Hugoton Oil Field in Kansas
by the Stanolind Oil & Gas Company (later on Pan American Petroleum
Company) in 1948 ( Clark, 1949). The technique was originally named
Hydrafrac method. 16 years later more than 400.000 hydraulic
frac-turing jobs have been performed in the free world. Early
developments focussed on technological aspects like pumping
capacities, hydraulic fluid viscosities and pumping rates, and
proppant materials. Hubbert & Willis (1957) were the first to
demonstrate conclusively the influence of tectonic stress to fracture
orientation. The mathematical concepts based on Kirsch (1898), Sneddon
(1946) or Barenblatt (1962) were devel-oped by Christianovich et al.
(1959), Perkins & Kern (1961), Howard & Fast (1957), or Geertsma & de
Klerk (1968). Fracture mechanics approaches to hydraulic fractur-ing
were suggested by Aboud-Sayed et al. (1978), Rummel (1987), or Rummel
& Hansen (1989). The powerful numerical simulator FRACPRO (RES 1991)
is available commercially since app. 1990. A summary of oil and gas
reservoir stimulation tech-nology is given by Economides & Nolte
(1987). For geothermal energy exploitation from HDR-systems hydraulic
fracturing was first applied within the LASL HDR project in 1975 ff
(e.g. Burns 1990). The hydrofrac technique was experimentally
investi-gated in the laboratory by Haimson (1968) and in-situ within
the Falkenberg granite shallow geothermal frac project (Kappelmeyer &
Rummel (1987), in the shallow French HDR project at Le Mayet de
Montagne (Cornet 1988) or in the Cornwall gran-ite HDR project at
about 2.5 km depth (Batchelor 1983). At Soultz-sous-Forêts almost 40
large-scale hydraulic stimulation experiments were carried out since
1988 which confirmed the concept of stimulation of pre-existing
fractures for the creation of a large scale heat exchanger at depth
(e.g. Baria et al. 1999). In this context hydraulic stimulation
experiments as e. g. carried out in 9 km deep KTB borehole to induce
microseismicity should be mentioned (Zoback & Harjes, 1997). Last not
least the hy-draulic stimulation of dry water wells may become
increasingly important for sustain-able water supply in many areas
(Rummel 1997, Klee & Rummel (2005). The devel-opment of intelligent
stimulation techniques and their physical understanding still is in
demand for economic methane production from impermeable deep coal beds
or for waste disposal into artificial fractures at great depth.
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