Wells – Processes – Graveling or filter forming
Patent
1989-08-01
1991-10-08
Neuder, William P.
Wells
Processes
Graveling or filter forming
166 51, E21B 4304, E21B 4310
Patent
active
050545531
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Phase Application of PCT/DE87/00558 filed Nov. 29, 1987 and based, in turn, on German National Application P 36 41 306.2 of Dec. 3, 1986 and P 37 13 577.5 of Apr. 23, 1987 under the International Convention.
FIELD OF THE INVENTION
The invention relates to a method of underground-water exploration.
BACKGROUND OF THE INVENTION
The German Patent 35 12 709 describes a generic method for the construction of wells in unstable rock, whereby between the filter gravel introduced in the area of the filter-pipe segment, referred to hereinafter simply as the "filter pipe", and the remaining portion of the annular space between the lengthening-pipe segment, hereinafter referred to simply as the "lengthening pipe", and the inner wall of the drill hole, a pumpable permanent-plastic or permanent-elastic seal is introduced. The annular space between the lengthening pipe and the inner wall of the drill hole is filled and sealed for sample taking.
With this known method a water sample can be taken only in the area of the actual filter pipe and the water bearing strata which may possibly exist above the filter pipe are hermetically and hydraulically sealed off from the openings in the filter pipe, due to the sealing of the annular space between the inner walling of the drill hole and the lengthening pipe.
The known method has the disadvantage that with this kind of well construction via hydraulic-system drilling, it is not possible to extract water in water-bearing rock strata with poor load-carrying capacity, since when the filter pipe is located in a water-bearing stratum which is loaded with noxious substances, it is necessary to redrill the entire drill hole. Before that, it is necessary to extract the filter pipes and the lengthening pipes. However, the extraction of lengthening pipes is almost impossible to perform, since due to the friction between the sealing material filling the annular space and the outside of the lengthening pipe, such a resistance against the extraction motion is created, that the drill holes are normally destroyed and collapse.
U.S. Pat. No. 4,366,862 describes equipment with which it is possible in sturdy mountain rock to define an underground area via spaced-apart packers, which can be pressed against the walling of the drill hole, in order to take out a sample of the liquid. Packers can be used only in sturdy rock. In rock that is not sturdy, where it is necessary to work with additives to the hydraulic drill fluid in order to stabilize the drill-hole wall, the packers destroy not only the stabilizing coating on the drill-hole wall, but also the drill-hole wall itself.
OBJECT OF THE INVENTION
It is the object of the invention to provide a method of underground-water exploration, which makes it possible to check any desired layer during the drilling of a well for the quality of the water-bearing stratum, without having to plaster the annular space between the lengthening-pipe segment and the walling of the drill hole and without having to fill sealing means into the annular space above the filter layer between the lower end of the lengthening-pipe segment and the drill-hole wall.
According to the invention a filter-pipe segment with an upwardly thereto connected lengthening-pipe segment are introduced at a distance from the drill-hole wall, and then filter gravel is introduced as a filtering layer into the annular space between the drill-hole wall and the filter-pipe segment, until the filter gravel protrudes over the top edge of the filter-pipe segment and fills the annular space between the drill-hole wall and the filter-pipe segment.
The invention provides that the annular space between the filter-pipe segment and the drill-hole wall is first filled with a filtering layer consisting of filter sand, preferably with a grain size of 0.3 to 0.7 or 0.7 to 1.2 mm, i.e. with a filter sand within the range of core-sand, and that after that water from the area of the filter-pipe segment is slowly pumped out, for the purp
REFERENCES:
patent: 3374836 (1968-03-01), Gribbin
patent: 3455387 (1969-07-01), Peters
patent: 3812911 (1974-05-01), Vann
patent: 4046198 (1977-09-01), Gruesbeck et al.
patent: 4669536 (1987-06-01), Ames et al.
patent: 4669540 (1987-06-01), Luoma et al.
patent: 4681163 (1987-07-01), Guidry et al.
Dubno Herbert
Neuder William P.
Terratronic GmbH
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