Measuring and testing – Sampler – sample handling – etc. – Capture device
Patent
1997-07-11
1998-07-07
Raevis, Robert
Measuring and testing
Sampler, sample handling, etc.
Capture device
7386474, G01N 104
Patent
active
057772428
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a bottom hole analysis and sampling system according to the preamble of claim 1.
Such systems are applied to carry out geotechnical ground analyses in order to determine the type and properties of grounds for the benefit of building and construction activities on land and off-shore. The invention relates in particular to systems in which bottom hole samples are taken and geotechnical experiments are carried out under the bottom end of drill holes. These samplings or analyses require that the velocity with which the probe or the sampling tube is pushed into the soil, is as constant as possible.
SUMMARY OF THE INVENTION
A system according to the prior art is provided with an outer tube comprising a series of extension tubes, provided at the bottom end with a drilling bit and wherein by rotation of the bit and rinsing with a suitable fluid a column of subterranean soil is removed by means of the tubes and the bit until the required depth is reached. A so-called cable tool is then lowered from the surface by means of the series of extension tubes, until it reaches a shoulder of the part of the outer tube having a decreased diameter. The tool is provided with a hydraulic cylinder in which a piston is connected to a rod which extends to the bottom end of the borehole via a hole in the middle of the drilling bit. The outer end of the rod is provided with a sampling tube or the analysis probe for the analysis of the properties of the subterranean soil. Via a tube fluid is fed under pressure from the surface to the hydraulic cylinder. When pressure is exerted on the top of the piston, the sampling tube or the analysis probe is driven into the ground under the bottom end of the borehole. The actual reactive force for the pressure on the rod is provided by the weight of the drill column which, if not sufficient, is supplemented by an extra weight which is coupled to the drill column at the surface. The equipment is provided with locking members, which after lowering of the tool, can be extended radially outward into a groove in the outer tube. When the rod is pushed into the ground, the reaction against the resistance to penetration is transmitted via the locking members to the outer tube. During lowering and raising, these hinged locking members are forcibly held in an inward position due to a tension in the hoisting cable, so that they can easily pass through the series of extension tubes. After lowering the tool onto the shoulder of the part with reduced diameter, the tension is removed from the hoisting cable and the locking members extend radially outward under the pressure of their own weight with the assistance of integrated springs so that, when the tool has been lowered correctly onto the shoulder, they fit into the groove of the outer tube. However, in practice this correct lowering is often hindered due to dirt on the shoulder, preventing the locking members from engaging the grooves so that the tool does not lock and when pressure is exerted on the piston by the compressed fluid, the tool will move upward instead of the rod being pushed downward into the ground. Even if the tool is positioned properly on the shoulder, the locking members may be hindered from engaging the groove in the outer tube due to dirt in the groove itself, resulting in the malfunctioning described above.
OBJECT OF THE INVENTION
It is the object of the invention to provide a bottom hole analysis and sampling system wherein this problem is effectively removed.
To this end the system according to the invention is characterized in that the pump system is connected to the extension tubes such that fluid under the upward seal in the outer tube and the extension tubes can be compressed, and that the hydraulic cylinder is provided at the top with a passage to allow this compressed fluid to enter above the piston and wherein the cylinder and piston are provided with a control device which allows the compressed fluid to pass through at one side of the piston with a substantially cons
Schrier Willem Henricus
Zuidberg Herman Maria
Fugro Engineers B.V.
Raevis Robert
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