Title of Invention

A DEVICE FOR DETERMINING ON A PRODUCTION SITE CHARACTERISTICS OF FLUID SAMPLES EXTRACTED FROM THE SUBSOIL

Abstract

The present invention relates to a device for determining on a production site characteristic of fluid samples extracted from the subsoil notably from petroliferous areas, comprising. in a thermostat-controlle onolosure a body comprising a first chamber and a second chamber arranged above the first one, the first chamber at least comprising a pointed end and the volume of these two chambers can be varied by shifting mobile elements in two cylinders means for shifting the twoi mobile elements means for transferring fluids into or out of the chambers and controlled communication means between the two chambers. characterized in that body comprises two coaxial radial coavities opening into this first chamber in the pointed part thereof, for am optical diaplay aaaembly consisting of two optical elements tightly Inserted respectively in the two cavities, comprising each a rigid sleeve a cylindrioal block made of a transparent material such as sapphire placed In line 'with the rigid sleeve and means for faatenins an and of an optical fiber connected to a photoemiasion or photorecaption element, for forming; the image of the end of the first chamber. PRICE: THIRTY RUPEES

Full Text

FIELD OF THE INVENTION The present invention relates to a device for determining, on a production site, characteristics of fluid samples extracted from the subsoil, notably from petroliferous areas, and more particularly to a compact site device that can be easily transported to production sites. The device according to the invention allows to perform on site extensive thermodynamic measurements by relieving operators of many operating sequences if need be. It also allows samples to be validated in order to check that they are really representative of the samplings that have been achieved, prior to sending them to a central laboratory for more complete analyses. These previous measurements and analyses performed on site with samples of very small volume allow to avoid the long and costly conventional solutions consisting in sending systematically samples to a distant laboratory, which must sometimes be repeated when it turns out that the samples are not valid and representative. Using the device according to the invention therefore allows to save time and to make significant savings. The device according to the invention allows for example, in the case of oil type petroleum samples, to measure their GOR (gas-oil ratio), the "bubble point" and the density of the oil, and in the case of gas type samples, to measure the 'dew point" of the gas phase, to draw up the liquid deposit curve, or to perform 1 qualitative analysis of the gaseous mixture. BACKGROUND OF THE INVENTION It is well-known that it is costumary to study the thermodynamic properties of samples extracted from wellbores with a view to developping underground deposits of effluents such as petroleum effluents. A good knowledge of these thermodynamic properties allows to assess the subsurface reserves, to optimize the production installation or to specify the methods of operation. The thermodynamic properties are calculated by using composition models into which data obtained by analyzing the samples are integrated. A so-called "PVT" type analysis method for example allows to measure the behaviour of samples certain parameters of which, such as pressure and temperature, are varied for example from values replicating those existing at their depth of burial to those prevailing at the surface. Methods of analysis of this type make it possible to measure important properties such as the "bubble point" indicating the appearance of a gas phase in the sample tested, the compressibility coefficient, the viscosity, the density, the GOR, etc, as it is known to specialists. The claimant's patent FR-2,666,415 describes a device for performing thermodynamic measurements on small-volume samples in a laboratory or on a site. This device comprises a thermostat-controlled enclosure, a supporting structure with two plates on either side of a transparent sapphire block for example and two small-section cylindrical chambers delimited by two sliding Distons moved in both chambers by mechanical drive means : threaded rods driven into rotation by shafts coupled with motive means. Seals are arranged in grooves provided in the wall of the two chambers, around both pistons. The first chamber is partly visible through the transparent block, and it ends in a bevel to the top of which opens a line communicating with the second chamber by means of a valve. A capillary tube connects the two chambers to each other and allows viscosity measurements to be performed on the samples. On account of its compactness, this prior device can be easily transported to the sampling sites. SUMMARY OF THE INVENTION The device according to the invention allows to measure directly on a production site characteristics of fluid samples extracted from the subsoil, notably from petroliferous areas. It comprises, in a thermostat-controlled snclosure, a body including a first chamber and a second chamber placed above the first one, the first chamber at least comprising a pointed end, and the volumes 3f these two chambers can be varied by shifting mobile elements in two :yHnders, means for moving the two mobile elements, means for transferring luids into or out of the chambers, and controlled communication means )etween the two chambers. The device is characterized in that the body comprises two coaxial radial avities opening into this first chamber in the pointed part thereof, for an optical lisplay assembly consisting of two optical elements tightly inserted respectively 1 the two cavities, comprising each a rigid sleeve, a cylindrical block made of a ransparent material such as sapphire arranged in line with the rigid sleeve and leans for fastening an end of an optical fiber connected to a photoemission or hotoreception element for forming the image of the end of the first chamber. Using these optical fiber display blocks allows to automate the phase separation operations with GOR determination with the aid of means for detecting the meniscus between the liquid phase and the gas phase of the sample. According to a first implementation mode, the two chambers are delimited respectively by two rods forming pistons provided each with seals, the device comprising motive means for controlling the displacement of the two rods, and a gasometer placed in the thermostat-controlled enclosure, which contributes to shortening the interconnection circuits and to decreasing condensation risks, tvhich are usually the cause of measuring errors. According to a first implementation mode, the first chamber is delimited by I rod forming a piston provided with seals, and the second chamber consists of he inner volume of a mobile piston gasometer placed on top of the first hamber. This implementation mode where the cell and the gasometer are integrated rovides a lighter device which can therefore be moved more easily on roduction sites, with a very short connection circuit between the cell and the asometer, which favours precise measurements. According to an embodiment, the body is fixed within the thermostat-controlled enclosure, the two mobile elements (and at least the rod in the first iwer chamber in case it is topped by a gasometer) are respectively integral with vo hangers that can each be shifted parallel to the two pistons by driving ispectively into rotation thrp.adpd rnHc flnrl tViA mr.fiwo rvi^^-o /'^.,^i. ^ ■ - motors or synchronous motors) for rotating the rods associated with each hanger separately or synchronously. The piston of the gasometer slides for example in a cylinder and it is provided with a rod connected to motive means suited to limit the pressure in the cylinder to a set value, so as to be able to measure at this pressure the volume of gas released by the expansion of the mixture. The device preferably comprises a unit for controlling the motive means and the optical display block, comprising for example a module for controlling the motive means intended to drive the threaded rods and an optical coding measuring circuit intended to detect the motions transmitted to the threaded rods and to convert them into volume variation measurements, and possibly a module for controlling the illumination of the first chamber through the first optical element, and for forming the image of an interface between phases through the second optical element. The device can also comprise a vibrator for stirring the fluids in the first chamber, the control unit comprising a circuit producing the signal to be applied to the vibrator. The device advantageously comprises a micro-computer programmed to perform automatic measuring procedures. According to an embodiment, the device comprises means for measuring the pressure at least in the first chamber, the control unit comprising a circuit for storing the calibration factors of these measuring means, as a function of a set temperature value associated with an element intended to select the calibration factors to be chosen as a function of this set temperature value assigned, in order to make the response of the measuring means independent thereof. The pressure measuring means include at least one membrane pressure detector arranged in a cavity provided in the wall of the first chamber, the membrane being flush with the inner surface of this chamber so as to limit the clearance volumes. The seals being mobile with the pistons, the clearance volumes between the two cylinders and the corresponding pistons remain substantially constant whatever their degree of penetration in their respective chambers. According to an embodiment, the body is fixed within the thermostat-controlled enclosure, the two pistons are respectively integral with two hangers that can each be moved parallel to the two pistons by driving threaded rods respectively into rotation and motive means (stepping motors for example) for rotating separately the rods associated with each hanger. The device preferably comprises a unit for controlling the motive means and the optical assembly. This control unit comprises for example a module for controlling the motive neans driving the threaded rods and an optical coding measuring system for ietecting the motions transmitted to the threaded rods and for converting them nto measurements of the concomitant volume variations of the two chambers. It •,an also comprise a module for controlling the illumination of the first chamber through the first optical element and for forming the image of an interface between fluid phases of the sample through the second optical element. The device can also comprise a vibrator for stirring the fluids in the first chamber, and the control unit can also comprise a circuit producing a signal to be applied to the vibrator. The device further comprises for example a means for measuring the pressure in the first chamber, the control unit comprising in this case a circuit for storing the calibration factors of this measuring means as a function of a set temperature value, associated with an element for selecting the calibration factors as a function of this set temperature value assigned, in order to make the response of the measuring means independent thereof. The device preferably comprises a micro-computer programmed to perform automatic measuring procedures. Accordingly the present invention provides a device for determining, on a production site, characteristics of fluid samples extracted from the subsoil, notably from petroliferous areas, comprising, in a thermostat-controlled enclosure, a body comprising a first chamber and a second chamber arranged above the first one, the first chamber at least comprising a pointed end, and the volumes of these two chambers can be varied by shifting mobile elements in two cylinders, means for shifting the two mobile elements, means for transferring fluids into or out of the chambers, and controlled communication means between the two chambers, characterized in that body comprises two coaxial radial cavities opening into this first chamber in the pointed part thereof, for an optical display assembly consisting of two optical elements tightly inserted respectively in the two cavities, comprising each a rigid sleeve, a cylindrical block made of a transparent material such as sapphire placed in line with the rigid sleeve and means for fastening an end of an optical fiber connected to a photoemission or photoreception element, for forming the image of the end of the first chamber. Other features and advantages of the device according to the invention will be clear from reading the description hereafter of an embodiment given by way of non limiting example, with reference to the accompanying drawings, in which: - Figure 1 diagrammatically shows a first cutaway view of the device in its thermostat-confrolled enclosure. - Figure 2 diagrammatically shows another cutaway view of the device, - Figure 3 diagrammatically shows a cutaway view of the means for driving the threaded rods into rotation, - Figure 4 diagrammatically shows the device associated with control modules, - Figure 5 diagrammatically shows a first implementation mode of the device suited for thermodynamic measurements on fluid samples, - Figure 6 is a block diagram of the control unit associated with its control micro-computer, and - Figure 7 diagrammatically shows a second implementation mode of the device suited for the validation of fluid samples. DESCRIPTION OF THE PREFERRED EMBODIMENTS The device comprises (Figure 1) a rigid body 1 consisting of two plates 2, 3 separated by a cylindrical block 4. The two plates of body 1 are fastened to a vertical post 5 of a rigid supporting frame 6. Body 1 is placed in a thermostat-controlled enclosure 7. Two threaded rods 8a, 8b set laterally apart from one another and rotating freely on their axis are arranged between an upper horizontal post 9 of frame 6 and the upper plate 2. Two similar rods 10a, 10b respectively in line with rods 8a, 8b are placed between the lower plate 3 of the body and another lower horizontal post 11 of frame 6. Two hangers 12, 13 are arranged on either side of body 1. They comprise threaded bores respectively suited to threaded rods 8, 10. The vertical translation of hangers 12, 13 is obtained by driving these threaded rods 8, 10 respectively into rotation. Two coaxial cylindrical chambers 14, 15 (Figures 2 to 5) with a conical bottom or end are provided through body 1. They communicate with each other at their points by means of a fine line 16 controlled by a valve V5. Two pistons 17, 18 provided each with a conical end suited to the shape of the chambers slide in the two chambers. The two pistons are respectively integral with the two mobile hangers 12, 13. Each one is provided with a seal J in the vicinity of its point. The peripheral clearance volume between each piston point and the corresponding seal J is thus constant whatever their degree of penetration in their respective chambers. The device comprises an optical display assembly consisting of (Figure 1) two optical elements 19, 20. Two coaxial radial cavities opening into the lower chamber 14 in the vicinity of its top are provided through body 1, respectively for the two optical elements 19, 20. Each one of them consists of a metallic frame with a central bore for a transparent block 21, for example made from sapphire. Each block is externally extended by an optical fiber end 22. One of the optical fibers 23a communicates with a light source such as a photoemission diode for example, the optical fiber 23b of the opposite optical element 20 provided with i photoreception element allowing to form the image of the conical end of lower chamber 14. of the draw-off zone at the top of the first chamber, with the sapphire block 22 and the illumination system, a very high precision is obtained for all the operations that are carried out on the fluids in the first chamber. This is the case in particular when all of the gas phase of a two-phase substance under pressure has to be drawn off with precision in this first lower chamber 14 and fed into the second chamber 15. The body comprises a cavity opening onto the lower chamber 14 near the top thereof, for a pressure detector PI. A flush-membrane detector PI (Figure 7) is preferably used at least in the first chamber 14 so as to minimize the clearance volumes likely to affect the measuring accuracy. Conductors 25 connect detector PI to a control unit situated outside the thermostat-controlled enclosure 7, which will be described in connection with Figures 4 and 6. Furthermore, a temperature probe ST is placed in body 1 in order to measure the temperature of the substance sample. A piezoelectric ceramic (not shown) associated with an ultrasonic generator SU (Figure 4) for stirring the substance sample fed into the first chamber 14 is fastened to the lower plate 3. The two chambers 14, 15 communicate respectively, by means of valves V2, V4, with a capillary pipe coil 27 (Figure 5) allowing to transfer fluid from one chamber to the other and to perform viscosity measurements. A valve V3 communicating with the fine line 6 between the two chambers 14, 15 allows the lower chamber 14 to be drained. A valve VI controls an access to the lower chamber 14 for delivering fluid samples to be analyzed. A driving shaft 28, 29 arranged in a perpendicular plane with respect to the axes of the threaded rods is respectively associated with each pair of threaded rods 8a, 8b and 10a, 10b (Figure 3). Each shaft is secured to one of the plates 2, 3 but it can rotate on its axis. Each one of them bears two gears 30a, 31a on the one hand and 30b, 31b on the other, that mesh with the threads of the corresponding rods 8, 10. The external ends of shafts 28, 29 are coupled each with a driving stepping motor MEl, ME2 (Figure 1) in a housing adjacent to the thermostat-controlled enclosure. The device also comprises a control unit CA (Figure 6) including : - a module 32 for controlling the two driving motors MEl, ME2 and an optical coding measuring circuit 33 for detecting the motions transmitted to the driving shafts 28, 29 of motors MEl, ME2 and for converting them into measurements of the concomitant volume variations of the first and of the second chamber 14, 15; ■ a circuit 34 for regulating the temperature. This circuit receives temperature lata from probe ST. It acts on heating elements 35 of the thermostat-controlled enclosure and it is suited to limit automatically the maximum temperature )revailing therein; a module 36 for controlling the illumination of the lower chamber 14 through )orthole 19 and for receiving the image of the interface between the phases eceived through porthole 20; a circuit 37 producing the signal to be applied to ultrasonic generator SU; - a circuit 38 for storing the calibration factors of pressure detector pi as a function of the set temperature value indicated by temperature probe ST, associated with an element 39 for selecting the calibration factors to be chosen as a function of the set temperature value assigned, in order to make the response of detector 31 independent thereof. The control unit also comprises circuits 40, 41 for detecting the position of the hangers with end-of-travel indicators, as well as a detection circuit 42 connected to pressure detectors PI, P2 for detecting an excess of pressure in the chambers above a set pressure value. A micro-computer 43 is associated with the control unit for running automatically the measurement sequences. The section of chambers 14, 15 is small enough to allow tests to be carried out with small substance volumes, of the order of some cm3, and the motive means are suited to bring the pressure in these chambers to several hundred bars, by shifting the rods 17, 18 forming pistons. The small volumes used allow to minimize safety problems on the one hand and the duration of the previous heating and stirring stages on the other hand. The substance sample being submitted to the temperature and pressure conditions prevailing in the underground zone where it was taken, its pressure can at first be lowered by moving back the first piston 17 sufficiently to be able to measure its compressibility for example. Lowering its pressure even further leads to the partial vaporization thereof. By opening valve V5, all of the gas phase can be transferred into the second chamber 15. According to the implementation mode of Figure 5, the device is associated with a gasometer 44 that is arranged in the climatic enclosure 7 in proximity to the body 1 of the cell. An inlet of the gasometer controlled by a valve V9 is connected to the second chamber 15 by valve V6. The gasometer can be connected to a vacuum pump (not shown) by a valve V7. This gasometer 44 allows to measure the volume of the gas taken in the second chamber after expansion to atmospheric pressure. This proximity of chamber 15 and gasometer 44 and their maintenance at the same temperature, which prevents condensation, allows preciser measurements to be performed. The gasometer is coupled for example with a chromatography apparatus 45 by means of a valve V8. The first chamber can be coupled, by means of valve VI, with a draw-off microcell 46 of a well-known type in order to measure the density of the substance studied. Pressure transfer of a sample into the first chamber of the device can also be achieved directly from a transport bottle 47. It can also be fed into microcell 46 at an intermediate stage, prior to transferring it into the first chamber 17. The microcell can be weighed in order to determine the mass fed into the cell. The density of the substance can also be determined. The embodiment of Figure 5 is particularly well suited for thermodynamic studies on samples with the possibility to measure the viscosity for example by coupling chambers 15 and 17 by means of coil 27. If it is only desired to validate a sample to check that it is really representative of the substances to be analyzed, the device is used for example according to the embodiment of Figure 7. In Figure 7, it can be seen that the second chamber consists of the inner volume of a gasometer such as 44. The rod 18 coupled with the motive means (8, 12, MEl) is here replaced by a piston 48 sliding in a cylinder 49. The rod of this piston is connected to motive means suited to maintain the pressure in cylinder 49 at most equal to a reference value, so as to be able to measure at this pressure the volume of gas released by the expansion of the mixture. Similarly, this gasometer is placed in the thermostat-controlled enclosure 7 for a higher measuring precision. With this layout where the cell and the gasometer are integrated, a lighter device is obtained, that can be more easily moved on production sites. Besides, the circuit connecting the cell to the gasometer is very short, which eliminates a known cause of measuring inaccuracy. Micro-computer 43 is suited to perform certain acquisition and operation control sequences. - It performs for example an automatic pressure control when, at a given set temperature value, the gas is transferred from the second chamber to gasometer 44 by being expanded to atmospheric pressure, in order to determine its volume under standard conditions (a correction is introduced to give the volume at 15°C). It also programs the set temperature value to be met. At the operator's demand, it carries out an acquisition of the measured pressure, volume and temperature (P, V, T) data. with successive stabilizations at several pressure stages. In this case, it scans the pressure and waits for its stabilization to carry out the acquisition of the P, V, T data prior to a new decompression. - At the operator's demand, micro-computer 43 can also carry out all the necessary P, V, T measurements and acquire them after validation, whether it be the pressure at the set temperature value, the determination of the volumes of the fluids contained in the first and in the second chamber at a set temperature and pressure value, of the volume of the gas phase obtained at ambiant temperature and atmospheric pressure. - Micro-computer 43 comprises storage means for recording the data acquired. - By means of programming, micro-computer 43 can be made to carry out a certain number of different operations according to whether the embodiment of Figure 5 is used to determine thermodynamic parameters of the sample studied and/or calibration parameters, or the embodiment of Figure 7 is used for sample validation operations. WE CLAIM: 1. A device for determining, on a production site, characteristics of fluid samples extracted from the subsoil, notably from petroliferous areas, comprising, in a thermostat-controlled enclosure (7), a body (1) comprising a first chamber and a second chamber arranged above the first one, the first chamber at least comprising a pointed end, and the volumes of these two chambers can be varied by shifting mobile elements in two cylinders, means for shifting the two mobile elements, means for transferring fluids into or out of the chambers, and controlled communication means between the two chambers, characterized in that body (1) comprises two coaxial radial cavities opening into this first chamber (14) in the pointed part thereof, for an optical display assembly consisting of two optical elements (19, 20) tightly inserted respectively in the two cavities, comprising each a rigid sleeve, a cylindrical block (21) made of a transparent material such as sapphire placed in line with the rigid sleeve and means for fastening an end of an optical fiber (23a, 23b) connected to a photoemission or photoreception element, for forming the image of the end of the first chamber. 2. The device as claimed in claim 1, wherein the two chambers are delimited respectively by two rods forming pistons provided each with seals, the device comprising motive means for controlling the displacement of the two rods, and a gasometer situated in the thermostat-controlled enclosure. The device as claimed in claim 1, wherein the first chamber (14) is delimited by a rod (17) forming a piston provided with seals (J), and the second chamber consists of the inner volume of a gasometer (44) fitted with a mobile piston (48) and placed on top of the first chamber. The device as claimed in claim 2, wherein the body is fixed in the thermostat-controlled enclosure (7), the two mobile elements (17, 18) are respectively integral with two hangers (12,13) that can each be shifted parallel to the two pistons by driving respectively into rotation threaded rods (8,10) and motive means (MEl, ME2) for rotating separately or synchronously the rods associated with each hanger. The device as claimed in claim 3, wherein the body is fixed in thermostat-controlled enclosure (7), at least one of the mobile elements (17, 18) is integral with a hanger (13) that can be shifted parallel to the mobile element by driving into rotation respectively threaded rods (10) and motive means (MEl, ME2) for rotating separately or synchronously the rods associated with the hanger. The device as claimed in claim 3 or 3, wherein piston (48) of gasometer (44) slides in a cylinder and it is provided with a rod (49) connected to motive means suited to limit the pressure in the cylinder to a set value, so as to be able to measure at this pressure the volume of gas released by the expansion of the mixture. The device as claimed in claims 4 or 5, comprising stepping type motors or synchronous motors. The device as claimed in any one of the preceding claims, wherein a control unit (CA) for controlling the motive means and the optical display assembly is provided. The device as claimed in the preceding claim, wherein the control unit comprises a module (32) for controlling motive means (MEl, ME2) in order to drive threaded rods (8, 10) and an optical coding measuring circuit (33) for detecting the motions transmitted to the threaded rods and for converting them into volume variation measurements. The device as claimed in claim 8, wherein the control unit (CA) has a module (36) for controlling the illumination of the first chamberr (14) through the first optical element (19) and for forming the image of an interface between phases through the second optical element (20). The device as claimed in any one of claims 7 to 10, wherein a vibrator (SU) is provided for stirring the fluids in the first chamber (14), and the control unit (C A) has a circuit (37) for producing the signal to be applied to the vibrator. The device as claimed in any one of claims 7 to 11, wherein a means (25-26) are provided for measuring the pressure in the first chamber (14), the control unit (CA) has a circuit (38) for storing calibration factors of this measuring means (25-26) as a fiinction of a set temperature value, associated with an element (39) for selecting the calibration factors as a function of the set tftmnsrature value. The device as claimed in any one of the preceding claims, wherein said means for measuring the pressure has at least one membrane pressure detector (PI) arranged in a cavity provided in the wall of the first chamber, the membrane being flush with the inner surface of this chamber so as to limit clearance volumes. The device as claimed in claim 2, wherein viscosity measuring means (27) is connected between the first and the second chamber (14, 15). The device as claimed in any one of the preceding claims, wherein a micro¬computer (43) programmed to perform automatic measurement procedures is provided. A device for determining, on a production site, characteristics of fluid samples extracted from the subsoil substantially as herein described with the reference of the accompanying drawings.

Documents:

1707-mas-1995 abstract.pdf

1707-mas-1995 claims.pdf

1707-mas-1995 correspondence-others.pdf

1707-mas-1995 correspondence-po.pdf

1707-mas-1995 description(complete).pdf

1707-mas-1995 drawings.pdf

1707-mas-1995 form-1.pdf

1707-mas-1995 form-13.pdf

1707-mas-1995 form-26.pdf

1707-mas-1995 form-4.pdf

1707-mas-1995 form-9.pdf

1707-mas-1995 others.pdf

1707-mas-1995 petition.pdf