EP2865810A1 - Improvements to devices for applying pressure to the wall of a well - Google Patents

Abstract

The present invention relates to devices for pressurizing a portion of the wall 1 of a well 2. The device is essentially characterized in that it comprises a cellular probe 10 comprising an input cell 16, a source 20 adapted to output an incompressible fluid at a pressure Pto, and means 22 for fluidically connecting the output 21 of the source 20 to the input 16 of the cell 11, the source 20 comprising at least one primary source 100 capable of delivering, at the outlet 43, a primary fluid under a pressure of value Pp less than the pressure value Pto, and a pressure amplifier 200 for bringing the pressure value Pp to the pressure value Pto, this amplifier of pressure comprising input means 201 fluidly connected to the output 43 of the source 100 and the output means 202 constituting the output 21 of the source 20. Application: realization of particular tests of ch ground.

Description

The present invention relates to an improvement to devices for pressurizing a portion of the wall of a well for carrying out load tests of a land in which the well is drilled.

To build any building or the like on a lot, it is better to check at least that this land will support such a building, that is to say its "load". To do this, one of the possible solutions is to make a well in the ground and to measure the loads that it can support, in other words to evaluate the deformations of the soil when it is subjected to given pressures.

Thus we know a system that is generally designated by the GEOMATECH Company, under the term CPV (Volume Pressure Controller).

The prior art in this area is illustrated by the content of the EP-2218827 in the name of the Applicant.

Such a system essentially comprises a so-called "tri-cellular" probe consisting of a so-called "central" cell comprising a feed inlet, and two so-called "guard" cells each comprising a feed inlet, these guard cells bordering in contact with the central cell respectively substantially at its two opposite ends, a first incompressible fluid source with an output fluidically connected to the supply input of the central cell, and a second source of compressible fluid having an output fluidically connected to the inputs feeding respectively the two guard cells.

This tri-cellular probe is also generally, but not necessarily, substantially annular in shape and is located on the wall of a borehole or inside a lantern tube placed inside a borehole. a cross section smaller than the cross section of the borehole.

To perform loading tests of the land in which the well is drilled, the drill pipe with the bare tri-cellular probe or in a lantern tube, positioned as defined above, is lowered into the well so that the probe is at the part of the soil to be tested.

Then, by means of a source of incompressible fluid, for example a sheet of water pressurized by a gas under pressure, the central cell is itself pressurized. The study of variations in pressure in the sheet, or water level in this sheet, allows in known manner to determine the value of the loading of the ground in which the tri-cellular probe is located. This method has been well known for a long time and, since it does not fall within the scope of the present invention, it will not be further developed here.

The method for measuring the loads that a terrain can withstand with a device as briefly described above generally gives good results but it does not allow, if necessary, very precise measurements, or to vary so very easy, reliable and perfectly determined, the volume of incompressible fluid in the central cell of the tri-cellular probe.

Also, the object of the present invention is to carry out an improvement to the device described above, to enable it to apply very high pressures in order to obtain better results than those it allows to get.

More specifically, the present invention relates to a device for pressurizing a portion of the wall of a well having the characteristics set forth in appended claim 1.

Other features and advantages of the present invention will appear in the course of the following description given with reference to the appended drawing for illustrative but not limiting purposes, in which:

The single figure shows the block diagram of an embodiment of the device according to the invention for pressurizing a portion of the wall of a well for carrying out load tests of the land in which is drilled this well.

It is first of all specified that, in the present description, if the adverb "substantially" is associated with a qualifier of a given means, this qualifier must be understood in the strict sense or approached.

The present invention relates to a device for pressurizing a portion of the wall 1 of a well 2 for, in particular, performing static loading tests of the terrain 3 in which the well is made by means of a radially expandable probe introduced in the well.

Such tests make it possible to obtain a curve of variation of the volumetric information of the terrain as a function of the applied stress, and to define a stress-strain relationship of the terrain to deduce three image parameters which are known to those skilled in the art, namely ( i) a modulus of deformation of the soil, (ii) a so-called creep pressure, and (iii) a limiting pressure.

The procedures making it possible to obtain these parameters are well known in themselves and will not be further described here, especially since they do not fall within the scope of the invention which concerns the device for enforce.

Having said this, the device comprises, with reference to the single FIGURE, a probe which, in the illustrated embodiment, is a tri-cellular probe 10. But this probe could be of a single-cell type, well known in itself. which is deduced without any difficulty from this tri-cellular probe illustrated and described hereinafter by way of example.

This tri-cellular probe consists essentially of a so-called "central" cell 11 comprising a feed inlet 16 and two so-called "guard" cells 12, 13 each comprising a feed inlet 17, 18, these two feed cells. guard bordering the central cell 11 in contact, that is to say with common wall portions, respectively substantially at its two opposite ends 14, 15.

The three cells 11, 12, 13 of the tri-cellular probe 10 have walls of elastic material and some wall portions are common, as shown in the single figure, between the guard cells 12, 13 and the central cell 11 According to a preferred embodiment, this elastic material is rubber.

The device further comprises a first incompressible fluid source 20 such as water or the like, with an outlet 21, first means 22 for fluidically connecting the outlet 21 of the first source 20 to the feed inlet 16 of the central cell 11, for example a rigid wall pipe and relatively undeformable at least under pressures of the order of those used for the implementation of the device.

This first source 20 consists of a primary source 100 capable of delivering, at an outlet 43, an incompressible primary fluid under a pressure value Pp and a pressure amplifier 200 to bring the pressure value Pp to a value of Pto pressure greater than Pp, this pressure amplifier further comprising input means 201 fluidly connected to the output 43 of the primary source 100 and the output means 202, these output means 202 constituting in fact the output 21 of the first source of incompressible fluid 20.

According to a very preferred embodiment, the primary source 100 is constituted, as illustrated in the single figure, by a jack 40 comprising a cylinder chamber 41 defined along a longitudinal axis 42, this cylinder chamber comprising a supply outlet 43, this output of supply 43 being located substantially at a first 44 of the two ends 44, 45 of the cylinder chamber.

The jack also comprises a piston 46 mounted to slide sealingly in the cylinder chamber 41 by delimiting therein two parts 47, 50 with variable volume as a function of the displacement of the piston 46, a first portion 47 able to be filled with an incompressible primary fluid. and which has the power output 43, and a second portion 50 which does not include this power output 43.

The jack also comprises a control rod 48 and means for linking a first end 49 of the control rod to the piston 46 so that the control rod is located at least partially in the second portion 50 of the cylinder chamber 41. means for linking a first end 49 of the control rod 48 to the piston 46 may be of different types: welding, screwing, interlocking, etc.

The device further comprises means 60 for controlling the translation of the control rod 48 substantially along the longitudinal axis 42 so as to slide the piston 46 into the chamber cylinder 41 of a predetermined quantity, which will be predetermined by the skilled person to perform the tests he wishes to perform. The sliding of the piston 46 will consequently vary at least the volume of the portion 47 of the cylinder chamber 41, this volume variation being in fact proportional to the translation of the piston.

According to an advantageous embodiment which facilitates the operation of the control rod 48, the length of the latter is determined so that, whatever the position of the piston 46 in the cylinder chamber 41, the second end 51 of this rod emerges from the second end 45 of the cylinder chamber 41, which allows easy handling.

However, according to a particularly advantageous embodiment, the means 60 for controlling the translation of the control rod 48 in one direction or the other (increasing or decreasing the volume of the cylinder chamber portion 47) comprise motor means 61 comprising a shaft outlet 62 adapted to be rotated about an axis of rotation 63, and coupling means 64 of the output shaft 62 with the control rod portion 48 emerging from the cylinder chamber 41.

These coupling means 64 have the function of transforming a rotation of the output shaft 62 into a translation of the control rod.

In an embodiment that is very preferential and particularly advantageous, both in terms of the simplicity of its implementation and that of the precision that can be obtained for the displacement of the control rod 48, these coupling means 64 consist of a ball screw 65 mounted in cooperation with the control rod, and a mechanical speed reducer, for example of the gear type 66 or the like, with two inputs, a first input being connected to the ball screw 65 the second input being linked to the output shaft 62.

A ball screw is a mechanism for converting a rotational movement into a translational movement, usually a helical link. Such a ball screw is well known in itself and will not be more fully described here.

As for the pressure amplifier 200 defined above, it consists of a first cylinder 212, a second piston 211 slidably mounted in this first cylinder delimiting a first variable volume chamber 210 fluidly connected by the input means 201 to the supply outlet 43 of the primary source 100 described above, a second cylinder 222 having the output means 202, a third piston 221 slidably mounted in the second cylinder by delimiting a second variable volume chamber 220 filled with an incompressible fluid which may be of the same type as the primary fluid that fills the portion 47 of the first chamber 41 defined above, and means 230 for connecting the second and third pistons 211, 221 so that the displacement of the third piston 221 is a function of the displacement of the second piston 211.

According to a preferred embodiment, these means 230 for connecting the second and third pistons 211, 221 consist of a rigid and solid connection depending on the pressures that are required, so that the displacement of the third piston 221 is equal to the displacement of the second. piston 211. As for the second and third pistons themselves, they are made so that the areas S2 and S3 of their surfaces respectively subjected to fluid pressures Pp and Pto are linked by the following relation: $\frac{S2}{S3}=\frac{\mathit{pto}}{\mathit{pp}}\mathrm{.}$

Very advantageously, the rigid connection 230 consists of a rigid and solid rod whose two ends are respectively integral with the second and third pistons 211, 221.

According to an industrially preferred embodiment, the first and second cylinders 212, 222 are coaxial and integral with each other, as illustrated in the single figure attached.

The device comprises, as in the prior art when the cellular probe is a tri-cellular probe such as that illustrated in the single figure, a second source of compressible fluid such as gas, generally air, having an outlet 31, and second means 32 for fluidically connecting the output 31 of the second source to the supply inputs 17, 18 respectively of the two guard cells 12, 13, these second fluid connection means 32 being of the same nature as the first means 22 defined above.

In one possible embodiment, the device may further comprise a central core 70 having a cross section smaller than the cross section of the well 2 and the tri-cellular probe 10 then has a substantially annular shape and is situated on the outer wall 72 of this central core 70 to be in the well 2, in the space 71 between the outer wall of the central core and the wall 1 of the well 2.

This central core 70 is generally fixedly positioned at one end of an operating rod which serves to lower the device in the well 2.

In practice, as illustrated in the attached figure, the second source of compressible fluid 30 consists of a reserve of the compressible fluid, such as a cylinder of gas well known in itself, having an outlet and an adjustable pressure regulator connected to this outlet for adjusting the pressure of the gas to a desired value that the skilled person knows to determine.

The operation of the device according to the invention is deduced from the operation described in the prior document referenced above without the need to describe it more specifically here, for the sole purpose of simplifying the present description.

It is however emphasized that the device according to the invention has, compared to the previous devices, the following advantage: its structure allows it to be used with one or other of the two types of probe, single or triple for example, by delivering a pressure of 1000 bar for a single-cell probe, and a pressure of 500 bar for a tri-cellular probe.

Claims (7)

Device for pressurizing a part of the wall (1) of a well (2) comprising: A cellular probe (10) comprising at least one cell (11) provided with a feed inlet (16), A source (20) capable of delivering, at an outlet (21), an incompressible fluid under a pressure of Pto value, and Means (22) for fluidically connecting the output (21) of said source (20) to the supply input (16) of said cell (11), characterized in that said source (20) is constituted by: A primary source (100) capable of delivering, at an outlet (43), an incompressible primary fluid under a pressure of value Pp lower than the pressure value Pto, and A pressure amplifier (200) for bringing the pressure value Pp to the pressure value Pto, this pressure amplifier comprising input means (201) fluidly connected to the output (43) of the primary source (100) and output means (202), said output means (202) constituting the output (21) of the source (20). Device according to Claim 1, characterized in that the primary source (100) consists of: An actuator (40) comprising a cylinder chamber (41) defined along a longitudinal axis (42), said cylinder chamber comprising a supply outlet (43), said supply outlet (43) being situated substantially at a first ( 44) of the first and second ends (44, 45) of said cylinder chamber, a first piston (46) sealingly slidably mounted in said cylinder chamber (41) defining two variable volume portions (47, 50) therebetween. the displacement of said first piston (46), a first portion (47) capable of being filled with an incompressible primary fluid and comprising said supply outlet (43), and a second portion (50) not comprising said output of power supply, a control rod (48), means for connecting a first end (49) of said control rod to said first piston (46) so that the control rod is located at least partially in the second portion (50) of the cylinder chamber (41), and Means (60) for controlling the translation of said control rod (48) substantially along said longitudinal axis (42) so as to slide said first piston (46) into the cylinder chamber (41) by a predetermined amount. Device according to one of claims 1 and 2, characterized in that the pressure amplifier (200) consists of: A first cylinder (212), A second piston (211) slidably mounted in said first cylinder delimiting a first variable volume chamber (210), said first chamber being fluidly connected by the input means (201) to the supply outlet (43) the primary source (100), A second cylinder (222), and A third piston (221) slidably mounted in said second cylinder, delimiting therein a second variable volume chamber (220), said second chamber being filled with an incompressible fluid and having the outlet means (202), and • means (230) for connecting the second and third pistons (211, 221) so that the displacement of the third piston (221) is a function of the displacement of the second piston (211). Device according to claim 3, characterized in that the means for connecting the second and third pistons (211, 221) consist of a rigid connection (230) so that the displacement of the third piston (221) is equal to the displacement of the second piston (211), the areas S2 and S3 of the two surfaces respectively of the second and third pistons (211, 221) which are subjected to fluid pressures respectively of values Pp and Pto being linked by the following relation: $$\frac{\mathit{S}2}{\mathit{S}3}=\frac{\mathit{pto}}{\mathit{pp}}\mathit{.}$$

Device according to claim 4, characterized in that the rigid connection (230) consists of a rigid rod whose two ends are respectively integral with the second and third pistons (211, 221). Device according to one of claims 3 to 5, characterized in that the first and second cylinders respectively of the first and second variable volume chambers (212, 222) are coaxial and integral with each other. Device according to one of the preceding claims, characterized in that said cellular probe (10) is one of the following probes: single-cell probe, tri-cellular probe.

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