Measuring and testing – Borehole or drilling – Fluid flow measuring or fluid analysis
Patent
1997-09-04
2000-06-20
Patel, Harshad
Measuring and testing
Borehole or drilling
Fluid flow measuring or fluid analysis
7315233, E21B 4710
Patent
active
060763981
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a measurement procedure and a flowmeter as defined in the claims.
Especially when searching for suitable places for final placement of nuclear waste, it is necessary to obtain information as to what sort of currents are occurring in the rock and its crevasses, i.e. what are the directions and velocities of flow of the currents.
In such measurements, the small volume flows and low flow rates cause problems. In prior art, a method used for determining the magnitude of flow is to separate a certain portion of a hole cut in the rock and to fill it with a suitable mixture or solution. By monitoring the changes in the concentration of this mixture or solution, it is possible to measure the flow. However, this method provides no information about the direction of the flow.
Attempts to determine the flow directions include the use of various marking substances whose passage in the chinks in the rock can be monitored.
A problem with all known methods for flow measurement is that they are slow. Since the rates of flow are of the order of a milliliter per hour, performing a single measurement generally takes months and thus getting results from a large area and multiple bore holes is an expensive and slow business.
SUMMARY OF THE INVENTION
The object of the invention is to eliminate the drawbacks mentioned above. A specific object of the invention is to produce a new procedure and flowmeter by means of which it is possible to measure very small currents in a relatively short time and obtain information about both magnitude and direction of flow.
As for the features characteristic of the invention, reference is made to the claims.
In the procedure of the invention, a certain longitudinal volumetric section is separated from a bore hole made in the rock and flow measurements are performed within this section. The volumetric section is divided in the longitudinal direction of the hole into sectors extending throughout the section, e.g. four 90.degree. sectors, in such a way that the sectors form separate spaces isolated from each other in the volumetric section. The sectors are then connected together via flow ducts permitting free flow between the sectors. After this, by using sensors placed in the flow ducts, the water flow values, i.e. the directions and velocities of flow between the sectors are measured.
Thus, the procedure of the invention is based on a solution whereby a given portion of a bore hole is divided longitudinally into parts or sectors and any currents into or out of the sectors are concentrated or collected in a suitable flow duct system so as to permit the flow in different sectors to be measured.
The flow in the flow duct is preferably measured by generating a suitable impulse in the current and by monitoring the movement of the impulse to discover the direction and velocity of the flow, which, together with the cross-section of the flow duct, can be used to determine the flow rates. The impulse used is preferably an extremely small thermal impulse, e.g. of the order of 1/1000.degree., whose movement is monitored. The thermal impulse must be very small to avoid producing turbulence in the tiny currents and to ensure that the heat will not be conducted back against the direction of flow. In this way, measurements can be made on extremely small currents, of the order of one milliliter per hour.
The flowmeter of the invention consists of a long cylindrical body comprising two ring-shaped sealing elements expandable by means of internal pressure, placed at a distance from each other in the longitudinal direction of the hole so that a certain volumetric section can be pressure-tightly separated from the hole. Likewise, the flowmeter correspondingly comprises dividing elements expandable against the surfaces of the hole, by means of which the volumetric section can be pressure-tightly divided into at least three, preferably four sectors extending from one sealing element to the other.
The sectors are interconnected via the flow ducts and an
REFERENCES:
patent: 2733605 (1956-02-01), Buck
patent: 3103813 (1963-09-01), Bourne et al.
patent: 3357492 (1967-12-01), Hubby
patent: 3379059 (1968-04-01), Wiley
patent: 5184677 (1993-02-01), Dobscha et al.
patent: 5226485 (1993-07-01), Dobscha et al.
Patel Harshad
Posiva Oy
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