WO2014049234A1

WO2014049234A1 - Device for sampling at a depth

Info

Publication number: WO2014049234A1
Application number: PCT/FR2013/052156
Authority: WO
Inventors: Michel BRACH; Frédérick GAL; Alain GADALIA; Hélène PAUWELS
Original assignee: Brgm
Priority date: 2012-09-28
Filing date: 2013-09-18
Publication date: 2014-04-03
Also published as: FR2996249A1; FR2996249B1

Abstract

The invention relates to a device for sampling at a depth (1) including: a tube (2) having an opening that is controlled by a first valve (3) downstream from which an opening that communicates in a first enclosure (4) is located, said first enclosure also communicating, via a flexible tube (5), with a variable-volume chamber(6) located downstream therefrom, said flexible tube (5) including an opening (7) controlled by a second valve (8) communicating toward the outside of said flexible tube, a third valve (9) controlling the passage inside said flexible tube (5) and placed upstream from said opening (7), and a fourth valve (10) controlling the opening of said variable-volume chamber (6) and placed downstream from said third valve (9).

Description

DEVICE FOR DEPTH SENSING

Technical area

The present invention relates in particular to the field of sampling fluid, and more particularly water and gas, in drilling.

The present invention more particularly relates to a device for the sampling of a fluid in depth and the surface treatment of the different phases (liquid and gas) before any contact with the atmosphere.

In boreholes exploring or crossing aquifer levels, it may be particularly interesting to take samples to precisely determine their composition. In some cases, it may be interesting to know the composition of fluids taken, for both the liquid phase and the gas phase. This is particularly relevant in response to requests from the administration for the monitoring of the integrity of groundwater bodies and the maintenance of their good chemical status (integrity of future C02 storage sites, study and remediation of Contamination in volatile elements ...).

The separation of the phases and the conditioning, carried out on the surface, will make it possible to recalculate the initial composition of the fluid in depth. This makes it possible to overcome the constraints related either to the direct rise of the fluid by pumping (modification of the pressure / temperature conditions) or to its removal from the bottom via a closed bottle (requires a pressure maintenance).

Indeed, in the well, the liquid is subjected to a pressure such that the quantity and nature of the gases dissolved in said liquid will vary greatly if it is brought to the surface without precaution. In depth, a fluid, given the hydrostatic pressure and the temperature, is in the vast majority of cases in monophasic form. For example, in the case of a water rich in CO2, the bubble point, below which the mixture is monophasic - water + dissolved CO 2 - is very rarely greater than 12 bar (ie 120 m of water column). When this fluid is brought back to the surface, the decrease in pressure causes the formation of a diphasic mixture: one phase will be constituted by free gases, the other representing the liquid and some residual gases in the dissolved state.

Degassing can be avoided by using bulky devices that are lowered to the place of sampling.

The applicant has developed a simple tool, inexpensive and easy to implement. This tool makes it possible to take samples of water in boreholes and / or deep piezometers.

This sampler is either permanently installed as part of periodic monitoring, or used in one-off samples to answer a given problem. It can be triggered by an operator or fully automated.

Summary of the invention

The present invention relates in particular to a deep sampling device comprising:

a tube, whose opening is controlled by a first valve downstream of which is placed an opening communicating in a first chamber,

said first enclosure communicating, via a flexible tube, also with a variable volume enclosure placed downstream thereof,

said flexible tube comprising an opening, controlled by a second valve, communicating outwardly of said flexible tube, a third valve, controlling the passage inside said flexible tube, and placed downstream of said opening, and a fourth valve, controlling said variable volume chamber and placed downstream of said third valve.

According to a preferred embodiment said fourth valve is a three-way valve which further communicates with a means for separating the liquid and the gas, placed downstream of said variable volume enclosure, and said inlet of said separation means is controlled by a fifth valve.

According to a preferred embodiment, said means for separating the liquid from the gas comprises a gas outlet and a liquid outlet and said liquid outlet communicates with a second chamber, called a dissolved gas sample, the inlet of which is controlled by a sixth valve.

According to a preferred embodiment, said means for separating the liquid from the gas comprises a gas outlet and a liquid outlet and said liquid outlet communicates with a third chamber, called a liquid sample, the inlet of which is controlled by a seventh valve.

According to a preferred embodiment, said means for separating the liquid and the gas comprises a gas outlet and a liquid outlet and said gas outlet communicates with a fourth enclosure, called a free gas sample, the inlet of which is controlled by an eighth valve.

The present invention also relates to a deep liquid sampling method characterized in that it implements a device according to the invention.

Brief description of the drawings

Figure 1 shows a block diagram of an embodiment of the device according to the invention. Figure 2 shows the first phase of sampling with the device according to the invention.

Figure 3 shows the 2nd phase of sampling with the device according to the invention.

Figure 4 shows the 3rd phase of sampling with the device according to the invention.

Figure 5 shows the 4th phase of sampling with the device according to the invention.

Figure 6 shows the 5th phase of sampling with the device according to the invention.

Description of the embodiments

Referring to Figures 1-6 are shown a device according to the invention and all the steps of the sampling method according to the invention. To help understanding, the case of a fluid sample (water + gas) carried out at 200 m depth with a hydrostatic level at 100 m will be taken as an example.

The device 1 according to the invention comprises in particular a tube 2, preferably flexible, and a flexible tube 5 which can be preferentially grouped in a body bitubique.

In the example illustrated in the figures, said twin-tube has a length of 210 m enclosing two flexible pipes 2, 5 of 4mm internal diameter. Of course the diameters of the pipes and their lengths are adaptable depending on the problem. This twin-tube is placed on a winder equipped with an odometer giving centimeter precision.

One end of the tube 2 and one end of the flexible tube 5 are each equipped with a valve 3, 12 allowing on the one hand the injection of a vector gas tube side 2 and the connection of the sampling device on the other hand 5. These two valves 3, 10, preferably three-way valves, are preferably intended to be maintained on the surface of the well. At the other end of the tube 2, is placed a first chamber 4 intended to serve as a buffer tank. The flexible tube 5 further comprises an opening 7, intended to be positioned in line with the target aquifer.

Said opening 7 is controlled by a second valve 8.

In the context of the present invention, the term "controlled" means that said valve, depending on its position, can block or allow the passage of a fluid at said opening. According to a preferred embodiment, said second valve 8 is a non-return valve positioned so that it is in the open position when the pressure outside the flexible tube 5 is greater than the pressure inside said tube flexible 5 and in the closed position in the opposite case.

In addition, said flexible tube 5 comprises a third valve 9, controlling the passage inside said tube 5 and placed downstream of said opening 7.

Preferably, said third valve 9 is a non-return valve positioned such that it is in the open position when the pressure upstream 5 is greater than the pressure downstream and in the closed position in the opposite case.

In the context of the present invention, the terms "downstream" and "upstream" refer to an arbitrary direction of flow from the free end of the tube 2 and opening to one of the other ends of the device 1 according to the invention.

Downstream of said third valve 9, the device 1 then comprises:

a variable volume chamber 6, intended to measure the volume of carrier gas to be extracted without interaction between the aquifer and the carrier gas during the process of raising the fluid. The opening of the said variable volume chamber 6 is controlled by a fourth valve 10 when the aquifer fluid appears at the valve 10 (thanks to the thrust printed with the carrier gas), the fluid is then directed to the valve 12 by action on the 3-way valve 10,

- A means 11 for separating the liquid and the gas, placed downstream of the valve 12. The inlet of said separation means 11 is controlled by a fifth valve 12. Said fifth valve 12 is preferably a needle valve. The entire device downstream of the valve 12 is initially kept under vacuum.

This means 11 for separating the liquid and the gas comprises a gas outlet 13 (in the high position) and a liquid outlet 14 (in the low position).

Said liquid outlet 14 communicates with a second chamber 15, called a dissolved gas sample, whose input is controlled by a sixth valve 16. Said second chamber 15 is preferably made of glass. Before sampling, it is ensured that this chamber is under vacuum. Said second chamber 15 may advantageously comprise additional valves at its inlet and outlet to facilitate sampling and subsequent analysis of the sample.

The liquid outlet 14 also communicates with a third chamber 17, called the liquid sample, the input of which is controlled by a seventh valve 18. Said third chamber 17 is preferably made of 316 stainless steel. Before sampling, this chamber is under vacuum. Said third chamber 17 may advantageously comprise additional valves at its entry and exit to facilitate sampling and subsequent analysis of the sample. Advantageously, said seventh valve 18 is a needle valve for controlling the flow rate of the fluid. Downstream of the third enclosure, the fluid can flow and allow sampling of fluids for all other chemical analyzes that do not require preservation of the sample from contact with the atmosphere.

The gas outlet 13 communicates with a fourth chamber 19, called the free gas sample, whose input is controlled by a seventh valve 20. Said fourth chamber 19 is preferably made of glass. Before sampling, this chamber is under vacuum. Said fourth chamber 19 may advantageously comprise additional valves at its entry and exit to facilitate sampling and subsequent analysis of the sample.

Advantageously, the device 1 comprises, downstream of the fifth valve 12, a pressure gauge gas (symbolized by P in the figures), placed downstream of the means 11 and upstream of the third enclosure 17, intended, on the one hand, to avoid an overpressure in the line, not compatible with the resistance of the glass enclosures, and, secondly, to verify the evacuation of the device at this point (downstream of the valve 12).

Finally, the sixth valve 16 is a valve which makes it possible, on the one hand, to evacuate the surface device (downstream of the valve 12) and to carry out the sampling for dissolved gases by means of a glass ampoule circulating (enclosure 15),

and, on the other hand, circulating the degassed fluid to a gas sampling device (chamber 19) and water conditioning (enclosure 17).

Taking a sample

As mentioned above, let's take the example of a sampling at 200 m depth with a hydrostatic level at 100 m. The sampling phasing

1st phase

The sampler being at the surface, the device 1 according to the invention is pressurized at 12 bar with the carrier gas (in dashed lines in FIG. 2) between the first valve 3 and the fourth valve 10. The vector gas bottle is disconnected as well as the the surface device downstream of the valve 10 so as to have an autonomous assembly for the introduction of the sampler to the desired coast. According to a preferred embodiment, said carrier gas is helium or nitrogen.

The twin-tube is lowered to the desired sampling depth (200 m). Since the pressure in the twin-tube is greater than the hydrostatic pressure, no fluid other than the carrier gas can be present in the entire pipework.

2nd phase

After a few minutes of rest allowing the particles suspended during the descent of the tool in the decanting work, the valves 3 and 10 are opened to decompress the system.

The fluid (solid line, Figure 3) is introduced into the tubes 2, 5 and will go up to the hydrostatic level.

We then have the following information:

- atmospheric pressure at the surface;

- 1250 ml theoretical volume gas side pipe 2, above the static level;

- 2250 ml upstream of the opening 7, corresponding to 1000 ml (volume of the first chamber 4) and 1250 ml volume of 100 m of inner diameter tube 4 mm);

- 1250 ml downstream of the opening 7, corresponding to the single internal volume of the tube; and 1250 ml of nominal gaseous volume on the pipe side, very suitably composed of the carrier gas used for the initial pressurization of the device.

3rd phase

This step will consist, in successive steps, in bringing up the fluid intended to be sampled while driving the carrier gas present towards the variable volume enclosure 6. This rise is made possible by a pressurization of the device thanks to the carrier gas at the level of the tube 2 and the non-return valve constituting the valve 8 preventing the fluid present in the device from escaping and the non-return valve constituting the valve 9 preventing the fluid located on the pipe side 5 to descend (Figure 4) . This step should be considered carefully to avoid contaminating the sample with the carrier gas. The additional volume provided by the first enclosure 4 constitutes in this sense an additional safety reserve. During successive pressurizing maneuvers, the variable volume chamber 6 makes it possible to evaluate the volume of vector gas present in the pipe-side device 5 and thus to prevent the carrier gas from reaching the enclosure 4.

4th phase (Figure 5)

Once the fluid is on the surface, the 3-way valve 10 is tilted from the chamber 6 to the fluid sampling device (to the valve 12). The vacuum is achieved throughout the portion between the valves 12 and 18, the vacuum control and its resistance in time being checked with the absolute pressure gauge p. This gauge will also control the pressure in the circuit during the release of free gases to avoid overpressure that may damage the glassware. The sixth valve 16 upstream of the second chamber 15 is then closed; it will be reopened during sampling for dissolved gases.

The fifth valve 12 (needle valve) is then opened gently. Given the pressure differential, the fluid will spread in the vacuum part which accelerates its degassing. When the pressure equilibrium is reached, a new pressurization with the carrier gas will make it possible both to raise formation fluid and to bring the aerial part of the device 1 to a pressure greater than atmospheric pressure. The entire operation is preferably controlled by the manometer to avoid damaging the device.

5th phase (Figure 6)

This step consists only in gently opening the seventh valve 18 (needle valve). Since the upstream pressure is greater than atmospheric pressure, the fluid can flow only to the third enclosure 17 and there can be no contamination by air.

The free gases accumulate in the upper part of the means 11. In order to be sure of collecting enough gas, it is sufficient to put up as much fluid as is judged useful by applying a differential pressure using the vector gas.

6th phase

Sample collection is then possible in the following order:

- The fluid present in the third chamber 17 is taken by first closing the valve downstream of said enclosure 17 and the valve upstream;

- Next, the free gas is collected by translation between the means 11 and the fourth chamber 19 (under vacuum);

- At the same time, the dissolved gas sample will be taken from the second chamber 15. Industrial Application

The above metrological description is intended in particular for the taking of spot samples and / or in explosive environments (ATEX zones).

As part of follow-ups, an automated version can be considered.

For this, the valves are replaced by pneumatic valves or solenoid valves. A suitable program is in charge of the management of openings and closures. An ultrasonic tank may also be installed just upstream of the means 11 to optimize the degassing speed. Similarly, the optimization of the vacuum in the sampling line can be done using an electric vacuum pump.

Claims

A depth sampling device (1) comprising:

a tube (2), whose opening is controlled by a first valve (3) downstream of which is placed an opening communicating in a first chamber (4),

said first enclosure communicating, via a flexible tube (5), with a variable volume enclosure (6) placed downstream thereof,

said flexible tube (5) comprising an opening (7), controlled by a second valve (8), communicating outwardly of said flexible tube, a third valve (9), controlling the passage inside said flexible tube ( 5) and placed downstream of said opening (7), and a fourth valve (10), controlling the opening of said variable volume enclosure (6) and placed downstream of said third valve (9).

2. Depth sampling device (1) according to claim 1 characterized in that the fourth valve (10) is a three-way valve which further communicates with a means (11) for separating the liquid and the gas, placed in downstream of said variable volume enclosure (6), and in that the inlet of said separation means is controlled by a fifth valve (12).

3. Depth sampling device (1) according to the preceding claim characterized in that said means (11) for separating the liquid and the gas 30 comprises a gas outlet (13) and a liquid outlet (14) and said liquid outlet (14) communicates with a second chamber (15), said dissolved gas sample, whose input is controlled by a sixth valve (16).

4. Depth sampling device (1) according to claim 2 or 3 characterized in that said means (11) for separating the liquid from the gas comprises a gas outlet (13) and a liquid outlet (14) and in that said liquid outlet (14) communicates with a third chamber (17), said liquid sample, the input of which is controlled by a seventh valve (18).

5. Depth sampling device (1) according to claim 2 characterized in that said means (11) for separating the liquid and the gas comprises a gas outlet (13) and a liquid outlet (14) and in that that said gas outlet (13) communicates with a fourth chamber (19), said free gas sample, whose input is controlled by a seventh valve (20).

6. Depth sampling device according to any one of the preceding claims characterized in that the second valve (8) is a non-return valve so that it is in the open position when the pressure outside the tube flexible (5) is greater than the pressure inside said flexible tube and in the closed position in the opposite case.

7. Depth sampling device according to any one of the preceding claims, characterized in that one end of the tube (2) is equipped with a valve (3), allowing the injection of a vector gas tube side (2). ).