EA021134B1

EA021134B1 - Detecting gas compounds for downhole fluid analysis using microfluidics and reagent with optical signature

Info

Publication number: EA021134B1
Application number: EA201171265A
Authority: EA
Inventors: Джимми Лоуренс; Дан Э. Анджелеску; Кристофер Харрисон; Цутому Ямате; Мэттью Т. Салливан; Роберт Дж. Шредер; Рональд Э.Г. Ван Хал; Бхавани Рагхураман
Original assignee: Шлюмбергер Текнолоджи Б.В.
Priority date: 2009-04-22
Filing date: 2010-04-22
Publication date: 2015-04-30
Also published as: EA201171265A1; MX2011011077A; US20100269579A1; BRPI1014955A2; EP2422195A1; WO2010122413A1

Abstract

A gas separation and detection tool for performing in situ analysis of borehole fluid is described. The tool operates by introducing a reagent to a test sample and causing the resulting mixture to flow through a microfluidic channel where optical testing is performed. The optical testing detects a change in a characteristic of the reagent in response to expose to one or more particular substances in the test sample. The test sample may be borehole fluid, a mixture of borehole fluid and scrubbing fluid subsequently mixed with reagent, a mixture of reagent and gas separated from borehole fluid, or a mixture of scrubbing fluid and gas separated from borehole fluid which is subsequently mixed with reagent. A membrane may be employed to separate one or more target gasses from the borehole fluid.

Description

The present invention mainly relates to the analysis of borehole fluid, and more specifically to the on-site detection of gaseous compounds in the borehole fluid using a reagent that provides optical recording in a microfluidic device in response to exposure to certain substances.

The level of technology

As is well known, the phase behavior and chemical composition of borehole fluids are useful information. For example, the concentration of gaseous components, such as carbon dioxide, hydrogen sulfide and methane, in the wellbore fluid is an indicator of the economic viability of developing a hydrocarbon field. CO concentrations ₂ and H ₂ § are of interest because carbon dioxide corrosion and hydrogen sulfide cracking under the action of stress, due to relatively high concentrations, are the dominant causes of mechanical failure of operating equipment. CH Concentration _four It is of interest as an indicator of the calorific value of gas wells. Therefore, it is desirable to be able to analyze fluids quickly, accurately, reliably and economically.

Numerous methods and equipment are available to perform fluid analysis in the laboratory. However, the extraction of samples for laboratory analysis is time consuming and prone to errors. Due to the difference in environmental conditions between the location in the wellbore and the location on the surface and due to other factors, some of the characteristics of the well fluids change when fluids are extracted to the surface. For example, since gaseous hydrogen sulfide readily forms nonvolatile and insoluble metal sulphides by reaction with many metals and metal oxides, analysis of a fluid sample extracted using a metal container may provide an inaccurate estimate of the sulphide content. This is a technological problem, because methods for analyzing fluids that are known for use on the surface are generally impractical in the environment that occurs in a borehole due to dimensional limitations, extreme temperature, extreme pressure, water and other factors. Another technological problem is the release of gases and discrete gas fractions from a well fluid, which usually exists in a borehole in the form of a multi-phase fluid.

Technological problems associated with gas detection in fluids have been studied in this and other research areas. For example, patent applications for the United States of America, 20040045350A1; separation. US patent application 20040045350A1 and patents Great Britain 2415047A and 2371621A describe the detection of gaseous compounds using a combination of infrared spectrophotometry and membrane separation methods. US patent application 20060008913 A1 describes the use of a polymer based on perfluorinated compounds for the separation of oil and water in a microfluidic system. US patent application 2006000382A1 describes a microfluidic system for chemical analysis in a well, in which a portion of an aqueous-based fluid sample is taken and mixed with a pH-sensitive reagent for use cases with low-temperature pH measurement. The authors of Toya et al. (LAB, 2005, Vol. 5, pp. 1374–1379) describe a system for measuring the concentration of H28 using the colorimetric method and microchannel washers with a cellular design. However, the described system and reagent are unsuitable for use in such environmental conditions in the well, which are the case when working in the oil fields. U.S. Patent 6,925,392B2 describes a microfluidic device that responds to specific fluid characteristics during operation. The device is removed and analyzed to measure desirable characteristics, such as electrical resistivity, chloride, calcium concentration, and other fluid properties. However, a real-time, microfluidic sensor system capable of operating in a wide range of temperatures and pressures and under harsh conditions, such as those encountered in oil field operations, has not yet been developed.

Summary of Invention

In accordance with an embodiment of the invention, a fluid sample analyzer for use in a wellbore is provided, comprising a first channel for introducing a fluid sample, a second channel for introducing reagent into a fluid sample and creating a mixed fluid whose characteristics change when there is in it substances, a microfluidic device for introducing a mixed fluid, a test module for determining inside the wellbore changes in the characteristics of the mixed fluid in ikroflyuidnom device for supplying the sensor signal indicative of identification of the change characteristics of the mixed fluid; and means for separating the sample fluid from the well fluid, located between the well fluid and the first channel, containing the membrane in the form of a twisted capillary tube.

In accordance with another embodiment of the invention, a method is proposed for detecting a substance of interest in a borehole fluid, using the above-mentioned analyzer and comprising the following steps: introducing a fluid sample through the first channel; introducing the reagent into the sample fluid through the second channel and creating a mixed fluid, the characteristics of which change when it contains the substance of interest; directing at least a portion of the mixed fluid into the microfluidic device; inside the wellbore, changes in the characteristics of the mixed fluid in the microfluidic device are determined by means of a test module.

One of the advantages of the invention is that the well fluid can be analyzed in situ. In particular, the reagent is injected into the sample of the test fluid and the mixture is tested inside the wellbore. Consequently, the time-consuming extraction of fluid and errors due to changes in fluid samples due to changes in conditions between the well and the environment are at least reduced.

The achievement of some of the advantages of the invention is facilitated by the use of microfluidic technology. In general, microfluidic devices represent a method of processing and manipulating fluid volumes of the order of nanoliters in a micrometric channel size, known as a microchannel. As a result, the flow of fluid inside the microchannel is laminar. Therefore, a static or active mixer can be used to enhance the mixing of fluids and achieve the magnitude of the mix ratio of mixed fluids. Microfluidic devices are distinguished by the fact that the treatment of microliters of fluid in the laminar flow regime provides fundamentally new possibilities for controlling the concentrations of molecules in space and time, as a result of which the determination of physical properties is facilitated. Therefore, it is clear that microfluidic technology provides advantages for analytical applications, including small prints, small sample volumes and reagents, in terms of the ability to carry out various processes, such as separation and detection, with high resolution and sensitivity, with low costs and for a shorter analysis time.

Brief description of the figures

FIG. 1 illustrates a downhole probe for separating and detecting gas in a borehole.

FIG. 2 illustrates the introduction of a reagent fluid and optical testing in a microfluidic device in more detail.

FIG. 3 illustrates an embodiment in which the well fluid is directly mixed with a reagent in a microfluidic device.

FIG. 4A-4C illustrate the mechanisms for feeding the sample of the test fluid and reagent into the microfluidic device.

FIG. 5A-5C illustrate the combination of mixing and optical detection functions in a microfluidic device.

FIG. 6 illustrates an alternative microfluidic optical device.

FIG. 7 illustrates an embodiment in which the wash fluid is mixed with the well fluid to create an intermediate fluid, which is then mixed with the reactant fluid before testing.

FIG. 8 illustrates an embodiment in which gas is separated from the well fluid using a membrane, and the reactant fluid is mixed with the separated gas before testing.

FIG. 9 illustrates an embodiment in which the gas is separated from the well fluid using a membrane, the wash fluid is mixed with the separated gas, and then the reactant fluid is mixed with the mixture of wash fluid and gas before testing.

FIG. 10 and 11 illustrate the use of a thin capillary membrane.

FIG. 12 and 13 illustrate an embodiment in which a six-way valve and a sampling loop are used to inject fluids prior to measurement.

FIG. 14A-14B illustrate an alternative alternative system based on the six-position valve of FIG. 12 and 13.

FIG. 15 illustrates a method according to the invention.

FIG. 16 illustrates a support structure for a capillary tube.

FIG. 17 illustrates the experimental result of a flow-injection analysis of sulphide dissolved in water.

FIG. 18 illustrates the experimental measurement result of gaseous H2g using a microfluidic membrane-based device made of thin-walled capillary tubes.

Detailed Description of the Invention

FIG. 1, a string of tools 100 is shown for measuring fluid characteristics in a borehole 102. The wellbore may be drilled through hydrocarbon formation 106 adjacent to

- 2 021134 impermeable layer 108, and various other layers, which are composed of overlapping rocks 110. A tool column, which may be part of a string of cable logging tools, a string of log tools while drilling or another device, acts on signals from the control device 104, which can be located on the surface. Controller 104 may also be capable of analyzing data. A tool column 100 is connected to a control device 104 by a logging cable for a tool that is lowered into a well on a cable, or a string of drill pipes for a tool for logging while drilling. The tool column 100 includes a gas analyzer 112 that is lowered into the wellbore to measure the physical properties associated with the fluid in the borehole or in the formation. The data collected by the gas analyzer 112 can be transmitted to the control device in real time via a wire cable or system for logging while drilling.

FIG. 2 illustrates the basic principles of operation of the gas analyzer 112 (FIG. 1). Reagent 200 is brought into contact with the sample of the test fluid 202 to produce the mixed fluid 204. Inside the mixed fluid 204, the reagent 200, the sample of the test fluid 202 or both exhibit a change in at least one physical characteristic due to the presence of one or more specific substances or classes substances in the sample of the test fluid. For example, and without limitation, the reagent may exhibit a color change if a substance such as CO is present in the mixed fluid. ₂ or H ₂ § or CH _four from the sample of the test fluid. In addition, the degree of change in characteristics may depend on the concentration of the substance, the duration of exposure, or both. The mixed fluid 204 is then allowed to flow through the microfluidic device 206, where the mixed fluid is tested. Testing can be performed using an optical test module designed to detect color change or specific transmittance shown by the reagent. The optical module may include a low dead space optical flow cell or a microfluidic optical flow cell. In one embodiment, the optical test module includes an optical emitter 208, such as a source of ultraviolet and visible radiation, and an optical receiver 210, such as a charge coupled spectrometer, which detects changes in color or optical absorption. The test module generates an output signal that is indicative of detected changes. In addition, the output signal can be an indication of the degree of change. The output signal is sent to an interpretative software circuit in control device 104, which processes the output signal to characterize the sample of the test fluid, for example, the detection of a specific gas or reaction products of a specific gas and reactants. In addition, the treatment may give an indication of the concentration of this gas in the well fluid. It will be understood that the processing software will include a computer program stored on computer readable media. As will be explained below, the sample of the test fluid may include a variety of different fluids, either individually or in combination.

The reagent 200 is selected depending on the type of gas or gases, determined and measured by the operator. For example, a reagent can be selected based on the ability to react with or absorb gas (or gases) of interest at a predictable rate or degree depending on the concentration of gas in the wellbore fluid. In addition, the reaction of the reagent to the effects of the gas or gases of interest must cause a change in the characteristic of the reagent, gas or other substance that can be registered and possibly measured. Examples of reagents that can be used to detect hydrogen sulfide gas include, but are not limited to, fluorescein merkuracetate, metal cation complexes and organic compounds, and organometallic materials combined with a variety of suitable solvents.

The microfluidic device 206 is formed by a robust housing that allows light to pass from the test module through the channel from the optical emitter to the optical receiver. The device 206 has a channel diameter of from about 100 nanometers to several hundred micrometers, and, in the case of a rectangular channel, at least one of its internal dimensions is less than a few hundred micrometers. The fluid flow inside a microfluidic device is characterized by the Reynolds number,

where b represents the most appropriate length scale, μ represents viscosity, g represents the density of the fluid, and Y _aud represents the average flow rate. The value of b may be 4A / P, where A represents the cross-sectional area of the device, and P represents the perimeter of the wetted surface of the channel. Ke has a magnitude of the order of a unit for typical applications of a microfluidic device, and laminar flow is assumed for Newtonian fluids, and fluids with negligible elasticity. In the present invention, the Ke value may be up to 5, for example, in the range from 0.01 to 50 μl / min (50 for low viscosity fluids). Due to the size of the microfluidic device and the properties of the reaction fluid, the flow of the reaction fluid through the device is laminar, that is, without turbulence.

FIG. 3 is a block diagram of an embodiment of a gas analyzer 112 (FIG. 1) in which the reagent 200 is mixed directly with the well fluid medium 300. This embodiment includes at least two inlet ducts 302, 304. Inlet duct 302 is used to accept the well fluid 300 and inlet channel 304 are used to receive reagent 200, for example, from a reservoir. The well fluid and the reagent are mixed in a static mixer 306, thereby creating a mixed fluid, such as metal sulfide in solution. The mixed fluid is then allowed to flow through the microfluidic device 206, in which the mixed fluid is subjected to optical testing. Then the tested fluid is discharged as waste.

A variety of means are known to initiate fluid flow. While the specific method of fluid flow is not critical to the invention, some alternatives may be described for completeness. In general, the flow of fluid through the microfluidic device 206 can be achieved by a differential pressure or electrokinetic method. A positive displacement piston pump can be used to create a flow under pressure. Electrodes can be used to create a stream excited by the electrokinetic method. The flow excited by the electrokinetic method is provided by an electric surface charge, including a double layer of counter-ions, which is formed on the surface of the channel casing. When using an electrode within the channel of a microfluidic device, an electric field is applied, the ions in the double layer move towards the electrode with opposite polarity. This causes the movement of the reaction fluid near the walls of the body, which is transformed by forces of viscous resistance into convective movement of the fluid. Alternatively, other means of exciting fluid flow could be used, including, but not limited to, piezoelectric-based micropumps and impeller pumps based on impellers.

FIG. 4A-4C illustrate the mechanisms for feeding the sample of the test fluid and reagent into the microfluidic device. In general, fluid flow is initiated by a pump, using pressure in a borehole with a throttle fluid limiter to control fluid flow, or some combination of methods. FIG. 4A specifically illustrates the use of independent pumps 401, 403 to initiate sample flow of the test fluid 202 and reagent 200, respectively, into a microfluidic device 206. FIG. 4b illustrates a variant in which the unit pump 405 provides the flow of the sample of the test fluid 202 to the tee 407. From the tee 407, the fluid 202 flows along two routes: the first route to the microfluidic device 206, and the second route to the piston cylinder 409. Flow of the fluid 202 Into the piston cylinder 409, it actuates the piston cylinder, thereby forcing the reagent to flow into the microfluidic device 206. The throttle restrictor 411 of the fluid can be used to control the pressure and volume of the reagent, th in microfluidic device. FIG. 4c illustrates an embodiment in which borehole pressure is used to initiate the flow of a sample of the test fluid 202 into tee 407. Thus, the pressure in the borehole actuates the piston cylinder to inject the reagent into the microfluidic device 206. The second choke restrictor 413 of the fluid is used to control the volume and pressure of the sample of the test fluid 202 introduced into the microfluidic device 206.

The various pumps described above can be, without limitation, commonly used plunger, piezoelectric pumps, impeller-based impeller pumps driven by mechanical rods or triggered by a magnetic field, preferably small enough to fit the size and flow rate required for microfluidic device. Some examples are described by the authors of Lack et al. In 2004 in the journal 1. Msgotey. Mugoeid., Volume 14, p. R35-P64; S. Uataia. M. SkatePat. ν.Κ. Ragakyag, A. Pe1p. N. NoGtapp. and M.A.M. Ssch, P1a8Ys Myugorit \ νίΐΗ ReggoYashFs AsschSAoop (Plastic micropump operating with the use of ferrofluidic medium), 1. Myuyemst1gotovyashsa1yy81et8, Volume 14 (No. 1), 2005; and le1 and others, the SROCEEOSHSSZHZTTGiTGOK from MNSNAMSE NUS1UTUR8. RART N (Proceedings of the Institute of Mechanical Engineers, Part H), ΙΟυΡΝΑΕ OR EYSTHERGYS ΙΝ MEIK'SHE. 2007, vol. 221; №2, pages 129-142.

In addition to controlling the flow of fluid to perform multiple tests, the flow of fluid can be varied to simplify testing within a larger range of gas concentrations. Since the volume of reactant fluid exposed to the separated gas is relatively small, the reactant fluid may become saturated if the flow rate of the fluid is relatively slow between mixing and testing, the gas concentration is relatively high, or both factors occur. To avoid saturation and thereby simplify measurement within a wider range of concentrations, the flow rate of the fluid can be varied so that, as the duration of the exposure,

- 4 021134 and the gas concentration, as indicated by the optical signaling, was transmitted to the control device as data. It will be appreciated that the indication of the flow rate of the reagent fluid may aid in detecting the separated gas at relatively low concentrations, while increasing the flow rate of the reagent fluid may help detecting the separated gas at relatively high concentrations.

FIG. 5A-5C illustrate some of the design features of the instrument used on the 555 chip. The mixing function may be important because the mixing characteristics differ between laminar flows and non-laminar flows. As a rule, microfluidic flows have a high Peclet number, for example, Pe = I.1 / E, where u = average flow velocity, 1 = channel size, and O = molecular diffusion capacity. The diffusion mixing time is given by the expression Φ ~ 1 ^L 2 / O. Therefore, the length of the mixing channel, necessary to achieve proper mixing of substances, linearly increases in proportion to the Peclet number (Lm ~ Rex1). For example, the average flow velocity is 500 μm / s, the channel size is 100 μm and the diffusion capacity of molecules is 10 μm. ² / s will require the duration of mixing and the length of the channel with values of about 1000 s and 0.5 m, respectively. Embodiments of the mixer 306 (FIG. 3) are shown in FIG. 5A. In many cases, a microfluidic device with a passive mixer design, such as a 501 herringbone zigzag design, in which a series of ribs is used to initiate a screw flow and increase mixing efficiency (see the authors §1gook et al., Bsheise, volume 295, 647-651 (2002) to discuss underlying principles). The mixing function can also be performed using a winding structure 503, including a series of rotations that promote mixing due to differences in distance traveled by the fluid as the direction changes, i.e., more rapid flow on the outside of the angle than on the inside of the angle. Alternatively, a micropump, such as an impeller pump based on an impeller, may act as a mixer. As specifically illustrated in FIG. 5B, the optical fibers 505, 507 may be interfaced with a microfluidic device so that light passes through a segment of the microfluidic device 206. For example, the fibers may abut a channel where the channel is laid at a right angle. Thus, light from a single fiber 505 enters the channel, and passes through it, and exits through another fiber 507. The variant in which the mixing function is included in the microfluidic device, for example, on a single chip with an optical detection module, is more specifically illustrated in FIG. 5C. More specifically, both the mixing device and the microfluidic optics are placed on the chip in such a way that the mixing action takes place upstream of the microfluidic optics.

Variants of microfluidic optical devices are illustrated in FIG. 6A and 6B. As shown in FIG. 6A, the microfluidic device can act as an optical waveguide such that a non-linear optical testing portion 611 is possible. In this embodiment, the channel that contains the fluid has an internal reflective coating with a proper refractive index so that the incident light does not come out. Light is introduced into the non-linear optical testing section 611 through optical fibers 505, 507, as already discussed above. One advantage of this embodiment is that the length of the optical testing section can be extended beyond the base length and width of the chip 555. As shown in FIG. 6B, the test section can alternatively be shaped such that it allows light to pass through the microfluidic device at right angles. In other words, the path of light on the test section 613 is linear and perpendicular to the flow path of the fluid. The underlying technology is described by the authors Moya! et al., Bailee NoschoriuYuShs5. Volume 1, 2007, p. 106.

FIG. 7 schematically represents a block diagram illustrating that numerous mixers 502,504 can be used with the optics of a microfluidic device 206 on a single chip 555. It will also be understood that multiple independent test modules can be implemented on a single chip (microfluidic optical devices with other components or without them, also known as sampling contours). For example, a matrix comprising multiple disposable test modules could be used with single-use valves 777 to introduce fluids so that the chip could be thrown away after all the modules have been used. Alternatively, reusable test modules could be used on the chip. One advantage of implementing a matrix of test modules is that characteristics such as fluid volumes and the length of the optical test section could differ among the test modules, thereby facilitating operation in a wider range of conditions and within a wider range of borehole fluids .

As suggested above, it may be undesirable to directly mix the reagent with the well fluid. One way to prevent such direct mixing is to use the wash fluid 500 to create intermediate fluid from the well fluid 300. The wash fluid is chosen to neutralize the characteristics of the well fluid that make it unsuitable for direct mixing with the reagent. The flushing fluid may also increase the solubility of the gas, which is advantageous if the solubility of the gas in the reagent is low. For example, in the case of an acid gas, an alkaline solution such as sodium hydroxide, alkanolamine derivatives such as triethanolamine, diethanolamine, and methyldiethanolamine can be used. Organic solvents, such as dimethylformamide and Ν-methylpyrrolidone, glycol based compounds (ethylene glycol, propylene glycol, diethylene glycol monobutyl ether) can also be used as wash / wash fluid. In practice, the washing fluid and the well fluid may be introduced into the static mixer 502 to create a sample of the test fluid. Then the sample of the test fluid and the reagent 200 are introduced into the second static mixer 504 to create a mixed fluid, which is tested in a microfluidic device 206. As discussed above, the mixers and optics of the microfluidic device can be implemented on a single chip as a single or multiple test modules.

FIG. 8 is a block diagram of an alternative embodiment of a gas analyzer 112 (FIG. 1), in which the sample of the test fluid is gas 400, which is separated from the borehole fluid 300 by a gas separation membrane 402. The well fluid 300 flows through channel 404 in one the side of the membrane, and the reagent fluid 200 from reservoir 406 flows through channel 408 on the opposite side of membrane 402. Holes associated with channel 404, which conducts well fluid, can be opened to the drill hole not in a way that provides an advantage to the flow of fluid inside the borehole to replenish the fluid inside channel 404. Channel 408, the conductive agent, is connected to the reactor tank 406 by one hole and to the static mixer 306 by another hole. The fluid that is mixed by the mixer flows into the microfluidic device 206. If present, one or more specific types of gases 400 are separated by the membrane 402 from the well fluid 300. The reagent 200 is mixed with the separated gas in the static mixer 306 at the end of the channel 408. Reagent 200 shows a change in physical characteristics in response to exposure to the separated gas in a mixture of gas and reagent. The change is then detected by optical testing in the microfluidic device 206, as already described above. The advantage of this option is that the reagent is not directly exposed to the borehole fluid. This separation may be desirable depending on the composition of the well fluid and the reagent. For example, the wellbore fluid may be so dark in color that it would cause errors in optical testing.

The membrane 402 has characteristics that prevent the passage of all but one or more selected compounds. Multiple gas separation membranes available on the market could be used. Such membranes are typically available as either a thin film or a thin-walled tube, any of which could be applied to the membrane 402. The membrane may be formed from any of a variety of materials, some of which may preferably be adapted to the conditions at the bottom of the well and the substance which is desirable to detect. One embodiment of the membrane is an inorganic, gas-selective molecular separation membrane having alumina as its basic structure, for example, an ΌΌΚ-type zeolite membrane. Another embodiment is a polymer membrane, such as a highly heat-resistant polymer membrane, such as Teioi AR (фирмыποηΐ), polydimethylsiloxane, or microporous polytetrafluoroethylene (Soge-Tech). In a polymer membrane such as Teiop AR (фирмыπΡοη или) or polydimethylsiloxane, gas molecules penetrate the membrane as a result of a dissolution-diffusion process, whereas in an inorganic or microporous membrane gas passes as a result of Knudsen diffusion. In the case of a zeolite membrane, a nanoporous zeolite material is expanded on top of the base material. Examples of such membranes are described in US patent applications 20050229779A1, 20040173094A1 and US patent 6953493B2. The membrane can be characterized by a pore size of about 0.3-0.7 μm, which causes a strong affinity for CO ₂ . Additional enhancement of the separation characteristics and membrane selectivity can be accomplished by modifying the surface structure. For example, to suppress the penetration of water through a membrane, a waterproof layer may be applied, such as a polymer based on a perfluorinated compound. Other variants of the separation membrane act either as molecular sieves or in the mode of adsorption-phase separation. These options can be formed from inorganic compounds, inorganic sol-gel, inorganic-organic combination compounds, inorganic-based material with an organic-based compound embedded inside the matrix, and any organic materials that meet the technical requirements.

FIG. 9 is a block diagram of an alternative gas analyzer 112 (FIG. 1), in which a sample of the test fluid is formed by mixing the wash fluid 500 with gas 400, which is separated from the well fluid 300 by a gas separation membrane 402. The well fluid 300 flows through channel 404 on one side of membrane 402, and the washing fluid 500 flows from reservoir 600 through channel 408 on the opposite side of the membrane. The flush fluid channel 408 500 is connected to the flush fluid reservoir 600 by one hole and to the static mixer 602 by another hole. If present, one or more specific types of gases 400 are separated by the membrane 402 from the well current 6 021134 of medium 300. The wash fluid is mixed with the separated gas in mixer 602, thereby creating a sample of the test fluid. The sample of the test fluid is then mixed with the reagent 200 in the second static mixer 604. The reagent demonstrates a change in physical characteristics in response to the gas in the sample of the test fluid. The change is then detected by optical testing in the microfluidic device 206, as already described above.

FIG. 10 and 11 illustrate the use of thin-capillary membrane 902 to provide selective gas permeability from well fluid 300. A capillary membrane allows a very high surface area to volume ratio to be achieved, and it is less prone to leakage from channel to channel compared to thin-film membrane with a planar flow-through channel. For example, the tube can be wound to form a compact structural form, and the required retention time of the reagent can be adjusted by adjusting the tube length or flow rate. In the case of a thin film membrane, only the flow rate can be adjusted. In addition, the formation of large-sheet membranes is relatively difficult. Wash the fluid can be used to facilitate the reaction, as already described above. Detection can also be facilitated by the flow of fluid in the start-stop mode.

Flow-injection analysis, proposed by Ruzicka and co-workers in 1974, is a reliable and reproducible method for conducting chemical analysis. A part of the sample is introduced into the flow of the reagent and then a change in characteristic is recorded. The accuracy of the method can be improved using a switching valve equipped with a sampling circuit.

FIG. 12 and 13 illustrate a specific embodiment of the gas analyzer 112 (FIG. 1), in which a six-valve valve 700 is used to introduce samples of the test fluids into the sampling circuit 702 before testing. The valve 700 has six holes 1-6. Hole 1 is used to continuously introduce a sample of the test fluid 202. Hole 4 is used to introduce reagent 200. The valve has two different configurations between which it can be switched. In the first configuration shown in FIG. 10, the hole 1 is connected to the hole 6, the hole 2 is connected to the hole 3, and the hole 4 is connected to the hole 5. In this first configuration, a sample of the test fluid 202 flows into the hole 1, into the hole 6, into the sampling loop 702 between the holes 6 and 3, and from the opening 3 to the opening 2, which is connected to a fluid waste piping or a disposal tank. The volume of the channel between hole 1 and hole 2 is known. Therefore, the volume of the sample fluid in the channel, and in particular the volume of the sample of the test fluid in the circuit 702 sampling, is fixed and known. Reagent 200 flows continuously from the 4 to 5 hole and into the mixer and the optical module. A basic measurement can be made in this configuration. The valve 700 is then switched to the second configuration shown in FIG. 13. In the second configuration, holes 3 and 4 are connected, causing the flow of reagent 200 to sample loop 700 through the hole. Then the sample of the test fluid and the reagent are mixed, moved through the sampling loop and out of the hole 5 into the static mixer 704 and the microfluidic device 206 for optical testing. One of the advantages of the application is to improve the control of the amount of reagent entered for each test cycle. Under certain circumstances, the inlets for the reagent 200 and the sample of the test fluid 202 can be reversed.

FIG. 14Ά-14Ό illustrate an alternative alternative system based on a six-position valve. This alternative design includes two plunger-type piston valves 1200 made of iron-based material coated with an inert, slightly elastic substance with a low coefficient of friction on the surface for better sealing. Valves 1200 can be actuated by magnetic devices 1202. When the magnets are activated on the left side, the reagent baseline signal is measured. When the magnets are activated on the right side, the plungers move and the fluid sample enters the sampling circuit (middle channel). When the magnets are again activated on the left side, the plungers are again shifted to the left, and the reagent pushes the “trapped” sample into the mixer and detector. The displacement of the plungers is adjusted to equalize the pressures of these fluids and also to use the pressure difference between these fluids to improve sealing.

FIG. 15 shows a method according to the invention. First, a sample of the well fluid is obtained and a known volume of reagent is prepared in steps 800, 802, respectively. Optionally, a wash fluid may be prepared at step 804. It should be noted that “cooked” means that the fluid can be introduced at a known volume or flow rate, and does not imply a method of preparation. Then, any of a variety of alternative methods can be used to obtain a sample of the test fluid. In one embodiment of the method, a known volume of reagent and sample of the well fluid is combined in step 806. In another embodiment of the method, the gas is separated from the well fluid in step 808, and the separated gas is combined with the reagent in step 810. In another embodiment of the method the fluid at step 808, and the separated gas is combined with the wash fluid at step 812, and the resulting fluid is combined with the reagent at step 814. In yet another alternative, the well fluid is combined with flushing fluid at stage 816, and the resulting fluid is combined with the reagent at stage 818. Since any of the methods could be applied, the results are shown as actions to logical OR at stage 820. Then the sample of the test fluid is subjected to optical testing at stage 822. The signal indicative of the test result is then transmitted to the processing circuit in step 824.

FIG. 16 illustrates a support structure for a capillary tube. As discussed above, a thin capillary tubular membrane 902 can be used to provide selective permeability of gas from the borehole fluid. The capillary membrane is mainly characterized by a high surface area to volume ratio and is less prone to leakage from the channel to the channel compared to a thin-film membrane with a flat flow channel. As illustrated, the tube may be wound into a compact structural form. In particular, the tubular membrane is wound around a support structure, which occupies less than a few percent of the total surface area.

FIG. 17 illustrates the experimental result of a flow-injection analysis of sulphide dissolved in water. The experiment was carried out at a temperature of 150 ° C, a pressure of 5200 psi (35.9 MPa), using a sampling loop with a capacity of 5 μl (microliters). A fluid sample was injected into the flow of reagent and a color change / optical signal was recorded using a microfluidic optical cell with a path length of 10 mm. The optical signal was observed at a wavelength of 400 nm. When using a wavelength of 850 nm (or higher) as the baseline / reference, the difference between these two signals can be used to quantify the sulfide content.

FIG. 18 illustrates the experimental result of measuring gaseous H ₂ § using a microfluidic membrane-based device made of thin-walled capillary tubes. A gas-permeable capillary tube was wound on a mechanical support. Then the reagent flowed into the capillary tube, for example, at a flow rate of 50 μl / min, and gaseous H ₂ § flowed from the supply side, that is, outside the capillary tube. The reaction product was determined using a microfluidic optical cell with a test track length of 10 mm. The signal was fixed at 400 nm and used. To improve accuracy, one could apply a baseline correction, for example, at a wavelength of 800 nm.

Although the invention has been described for the above exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that modifications and variations of the illustrated embodiments may be made within the disclosed concept of the invention. Moreover, while the preferred embodiments are described in connection with a variety of illustrative designs, it is clear to those skilled in the art that the system can be implemented using numerous specific designs. Accordingly, the invention should not be construed as limited to the above description, and limited only by the attached claims.

Claims

CLAIM

1. A fluid sample analyzer for use in a wellbore, comprising a first channel for introducing a fluid sample, a second channel for introducing a reagent into the fluid sample and creating a mixed fluid, the characteristics of which change when there is a substance of interest, a microfluidic device for mixed fluid input, test module for determining inside the wellbore changes in the mixed fluid characteristics in the microfluidic device, a sensor for signaling, showing its definition change characteristics of the mixed fluid; and means for separating the fluid sample from the well fluid located between the well fluid and the first channel, comprising a membrane in the form of a twisted capillary tube.

2. The analyzer according to claim 1, further comprising a component separator.

3. The analyzer according to claim 1, further comprising a pressure compensator for equalizing the pressure of the fluid inside and outside the analyzer.

4. The analyzer according to claim 1, further comprising a fluid supply module for introducing each respective fluid.

5. The analyzer according to claim 1, in which the signal supplied by the sensor is an indicator of the concentration level of the substance of interest in the borehole fluid.

6. The analyzer according to claim 1, in which the test module contains an optical emitter and an optical receiver, which determines the difference in color or specific transmittance.

7. The analyzer according to claim 1, wherein the reagent is selected from the group consisting of fluorescein mercuric acetate, metal cation complexes and organic compounds and organometallic materials combined with various suitable solvents, and combinations thereof suitable for use under conditions such as environment and well bore.

8. The analyzer according to claim 1, wherein the fluid sample is a borehole fluid.

9. The analyzer according to claim 1, in which the fluid sample is a borehole fluid mixed with a flushing fluid.

10. The analyzer according to claim 1, in which the microfluidic device comprises an integrated mixer.

11. The analyzer according to claim 1, in which the substance of interest for analysis can be transferred from one phase on the supply side to another phase on the permeate side.

12. The analyzer according to claim 1, in which the microfluidic device and the test module are combined into one device.

13. The analyzer according to claim 1, in which the capillary tube is supported by a structure that increases the diffusion area.

14. The analyzer according to claim 1, in which the membrane contains a thin film, a multilayer microporous or nanoporous membrane.

15. The analyzer according to claim 1, in which the fluid sample is a mixture of flushing fluid and well fluid.

16. The analyzer according to claim 1, further comprising a membrane disposed between the well fluid and the first channel, and the fluid sample is a mixture of flushing fluid and gas separated from the well fluid by a membrane.

17. The analyzer according to claim 1, in which the first and second channels are part of a multi-channel valve, and a test circuit is connected between the valve channels to enter a predetermined fixed volume of reagent.

18. The analyzer according to claim 1, further comprising a plunger for supplying at least one of the fluids in response to the discharge pressure of the other fluid.

19. The analyzer according to claim 1, further comprising a plunger for supplying at least one of the fluids in response to pressure in the wellbore.

20. The analyzer according to claim 1, in which the pressure is balanced by at least one of the spring or plunger, corrugated membrane and diaphragm membrane.

21. The analyzer according to claim 1, additionally containing a combined passive mixer and a membrane module.

22. The analyzer according to claim 1, additionally containing a thin-walled capillary tube, which acts as an optical waveguide and is connected to an optical source and detector.

23. The analyzer according to claim 1, in which numerous sampling loops are placed between the channels on a single chip.

24. The analyzer according to item 23, in which the sampling circuits are controlled by at least one of the multi-position switch valves and single-use valves.

25. A method for detecting a substance of interest in a borehole fluid, comprising using an analyzer according to claims 1-24 and comprising the following steps:

introducing a fluid sample through the first channel;

introducing the reagent into the fluid sample through the second channel and creating a mixed fluid medium whose characteristics change if there is a substance of interest in it;

directing at least a portion of the mixed fluid into a microfluidic device; determining within the borehole the characteristics of the mixed fluid in the microfluidic device by means of a test module.

26. The method of claim 25, further comprising the step of transmitting an output signal indicating a concentration level of the substance of interest in the well fluid.

27. The method according A.25, in which the test module contains an optical emitter and an optical receiver and which further comprises the step of determining the difference in color or specific transmittance.

28. The method according A.25, in which the introduction of the sample fluid contains the introduction of a borehole fluid.

29. The method according A.25, in which the introduction of the sample fluid contains the input of gas separated from the borehole fluid through a membrane.

30. The method according A.25, in which the introduction of the sample fluid contains the introduction of a mixture of flushing fluid and well fluid.

31. The method according A.25, in which the introduction of the sample fluid contains the introduction of a mixture of flushing fluid and gas, separated from the downhole fluid through a membrane.

32. The method according A.25, in which the first and second channels are part of a multi-channel valve and the test circuit is connected between the valve channels, while the input of the reagent contains the flow of a predetermined volume of reagent in the test circuit.