Measuring and testing – Borehole or drilling – Fluid flow measuring or fluid analysis
Patent
1998-05-01
2000-05-09
Raevis, Robert
Measuring and testing
Borehole or drilling
Fluid flow measuring or fluid analysis
G01N 100
Patent
active
060587725
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a sampling device for taking a water sample under pressure deep in a bore hole made in the earth.
Especially in investigations to determine the suitability of bed rock as a final place of storage for nuclear waste, it is necessary to obtain accurate information about the conditions prevailing inside the rock. Such information is obtained via hydrochemical analysis of water obtained from a hole bored in the rock.
In such cases, the holes are usually at least several hundreds of meters deep and the conditions deep in the hole are completely different from those on the ground surface. Therefore, a water sample pumped up from the hole to the ground surface no longer corresponds to a water sample deep in the hole, but, especially due to the pressure difference, the gases dissolved in the water under a high pressure are largely separated from the aqueous phase at normal air pressure.
In prior art, in an attempt to eliminate these problems, use has been made of a container in which a vacuum is created while on the ground. The container is then lowered deep into the hole, where it is filled through a valve. The container keeps the water sample at the pressure prevailing at the sampling depth, so the liquid can be studied in this pressurized state. However, this structure involves significant problems. When the container previously exhausted on the ground is filled, the water pressure falls radically and the dissolved gases may be separated from the aqueous phase. Maintaining the pressure while the container is being hoisted up is a further problem.
The object of investigation is natural water present in chinks in the rock, but the water obtained from a hole hardly ever represents it accurately. Even from rock chinks, a sample close to the natural condition can only be obtained after prolonged pumping.
Further problems in performing the measurements are also caused by the relatively small hole diameter of .0. 56 mm generally used in these investigations. Such holes cannot accommodate very complicated equipment.
SUMMARY OF THE INVENTION
The object of the invention is to eliminate the problems described above. A specific object of the invention is to present a new type of sampling device which enables a water sample taken from a deep hole to be accurately preserved in its original state corresponding to the actual conditions prevailing deep in the earth under a high pressure.
As for the features characteristic of the invention, reference is made to the claims.
The sampling device of the invention comprises parting elements, by means of which a sampling interval is separated from the rest of a bore hole, preventing free flow of water between the sampling interval and the rest of the hole. Moreover, the sampling device comprises at least one sample container, a flow pipe for extracting the water from the sampling interval, a sampling pipe for passing up the water supplied via the flow pipe, and a valve which can be used to direct the flow of the water alternatively directly from the flow pipe into the sampling pipe or from the flow pipe via the sample container into the sampling pipe and which also pressure-tightly closes and opens the sample container. Furthermore, the sampling device comprises a pressure pipe through which an operating pressure is supplied from the ground surface both to the parting element and to the valve.
The sampling device of the invention preferably comprises a limit pressure valve which allows direct flow of water from the flow pipe into the sampling pipe when the valve is closed but prevents direct flow from the flow pipe into the sampling pipe when the valve is open, so that the water flows from the flow pipe via the sample container into the sampling pipe.
The parting elements and the valve are preferably arranged to be operated via a common pressure pipe. In this case, the valve is provided with a counter-element, which may be e.g. a spring, which acts against the movement of the controlling element of the valve produced by t
REFERENCES:
patent: 3115775 (1963-12-01), Russell
patent: 3892130 (1975-07-01), Winget et al.
patent: 4295801 (1981-10-01), Bennett
patent: 4727936 (1988-03-01), Mioduszewski et al.
patent: 5095745 (1992-03-01), Desbrandes
patent: 5454275 (1995-10-01), Kabis
patent: 5799733 (1998-09-01), Ringgenberg et al.
Posiva Oy
Raevis Robert
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