MX2008004403A - Composition analysis of separated vapor and liquid phases using a gas chromatograph - Google Patents

Abstract

A method of analyzing a composition including live crude includes separating the composition into a vapor phase and a liquid phase. A composition of the vapor phase is determined with a gas chromatograph (50). At least a portion of the liquid phase is deposited in a vessel (12), and a headspace vapor phase is collected from the vessel (12). A composition of the headspace vapor is determined with the gas chromatograph (50).

Description

ANALYSIS OF COMPOSITION OF LIQUID PHASE AND STEAM SEPARATED THROUGH THE USE OF A CHROMATOGRAPH FIELD OF THE INVENTION The description refers to the analysis of pressurized test samples, which include hydrocarbons and fluids from reservoirs such as pressurized crude oil (pressurized). BACKGROUND OF THE INVENTION There are often cases in which it is desired to determine the composition of a fluid that contains the liquid and vapor phases. For example, in the context of oil and gas production, pressurized crude is analyzed for location purposes, as well as to determine gas to oil ratios, fluid shrinkage and compositional analysis. These fluids are typically produced at high pressures and temperatures. However, at atmospheric conditions, a gaseous or vapor portion of the fluid is released. For example, U.S. Patent No. 5,499,531 to Henderson discloses the passage of a liquid at a predetermined temperature and pressure through a gas / liquid separator at a substantially constant flow rate. The liquid releases a gas, which passes through a gas meter, while the liquid passes from the separator to a flow meter. The gas REF. : 191564 detached goes to a gas chromatograph, which measures the composition of the gas. Typically, it is not feasible to maintain the equipment to analyze the liquid and vapor phases at the production site. Testing pressurized crude oil away from the production site has certain advantages. Therefore, there is a need to remedy or diminish these disadvantages. BRIEF DESCRIPTION OF THE INVENTION In general terms, the concepts described herein encompass the systems and methods for analyzing a substance containing the liquid and vapor phases, including hydrocarbon samples and reservoir fluids such as crude oil under pressure. One aspect covers a method for analyzing a substance. In the method, the composition is separated into a vapor phase and a liquid phase, a composition of the vapor phase is determined with a gas chromatograph. At least a portion of the liquid phase is deposited in a container. At least a portion of the liquid phase is collected from the container. A vapor composition of the upper space of the liquid is also determined with the gas chromatograph. Another aspect includes a system to analyze a composition. The system includes a phase separator adapted to separate the composition into a vapor phase and a liquid phase. A gas chromatograph is adapted to receive at least a portion of the vapor phase and perform a compositional analysis on the vapor phase. A container is adapted to the input coupled to the phase chromatograph, adapted to remove at least a portion of the vapor from the upper space from the container and to the gas chromatograph. The gas chromatograph is adapted to receive at least a portion of the vapor from the upper space and perform a compositional analysis on the vapor of the upper space. Another aspect includes a method to analyze crude oil under pressure. In the method, a sample of the crude oil under pressure is collected from a production site. A vapor phase of the composition is analyzed with a gas chromatograph that resides at the production site. A liquid phase of the composition is analyzed with the gas chromatograph. The details of one or more embodiments of the invention are described in the appended figures and the following description. Other features, objects and advantages of the invention will be apparent from the description and the figures, and from the claims. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic of an illustrative analysis system constructed in accordance with the concepts described herein. Figure 2 is an illustrative system scheme to perform the analysis of the upper space with a gas chromatograph, in accordance with the concepts described herein. Figure 3 is a flowchart of an illustrative method according to the concepts described herein. Similar reference symbols in the various figures indicate similar elements. DETAILED DESCRIPTION OF THE INVENTION With reference firstly to Figure 1, an analysis system 10, illustrative, is described. The illustrative analysis system 10 operates to receive a fluid sample of a substance, such as pressurized or pressurized crude oil and perform a compositional analysis of all or part of the fluid sample. The illustrative analysis system 10 may also operate to determine one or more of the amount of vapor, the amount of liquid phases, or the amount of solid sample of the fluid. It should be noted, however, that crude oil under pressure under pressure is referred to in numerous parts throughout the description, the concepts described herein are applicable to the analysis of other substances. Also, the substance does not need to be fluid or completely fluid.

The analysis system 10, illustrative, includes a sample container 12 operable to receive the fluid sample, and substantially free the fluid sample to the remainder of the system 10. In certain embodiments, the sample container 12 can be removed from the system 10 and transported to collect the fluid sample. For example, the sample container 12 can be carried by an operator from the system 10 to a site where the sample will be collected, the sample is collected and the sample container 12 is returned to system 10. This eliminates the need to transfer the sample of fluid between multiple containers, such as between the site where the sample is collected and an intermediate sample container and from an intermediate sample container and the sample container 12. In other embodiments, the sample container 12 may remain connected to the sample container 12. rest of the system 10 throughout the operation and the collected sample deposited in the sample container 12, such as via an intermediate sample container. The illustrative sample container 12 of Figure 1 internally defines an elongated cavity 14 that sealingly receives a piston 16. The piston 16 divides the elongated cavity 14 into two distinct chambers, a flow fluid chamber 18 and a sample chamber 20. The sample chamber 20 is operable to receive the fluid sample through a valve (hereinafter referred to as "sample valve 22"). After receiving the sample fluid, the sample valve 22 can be closed to retain the fluid sample in the sample chamber 20. In certain embodiments, the sample container 12 can be configured to operate as a pyknometer. For this purpose, the maximum volume of the sample chamber 20 is precisely calibrated for the pressure and temperature. In addition, the "dry" weight of the sample container 12 is known precisely. The volume of the fluid sample, in this way, can be determined by adjusting the maximum volume of the sample chamber 20 for the temperature and pressure of the fluid sample therein. The weight of the fluid sample can be determined by weighing the sample container 12 containing the fluid sample, and subtracting the dry weight of the sample container 12. The density of the fluid sample can be determined by dividing the volume determined between the determined weight. In certain embodiments, the size of the sample container 12 may be selected to facilitate handling by the operator. A smaller container is more easily handled and carried by the operator. In one case, the sample container 12 has an internal volume of 10 cm3 when calibrated at 10 MPa and 20QC and is constructed of 316 stainless steel. To facilitate removal and return of sample container 12 to system 10, an outlet of the sample container 12 can be coupled to a quick release connection 30 that allows easy installation and removal of the sample container 12 from the rest of the system 10. In certain embodiments, the accessories of low dead volume are used in one or more sites of the system 10, for example, connections with the sample system 12. As noted above, the sample container 12 includes a piston 16 that divides the elongated cavity 14 into two distinct chambers, a chamber 18 of delivery fluid and a sample chamber 20. The sample container 12 may further include a valve (hereinafter referred to as "impulse valve 24") provided in combination with the chamber 18 of flow of impulsion. With the delivery valve 24 open, reception of the fluid sample in the sample chamber 20 drives the piston 16 in the elongate cavity 14 to expand the sample chamber 20 and reduce the delivery fluid chamber 18. A drive fluid can be introduced through the drive valve 24 to pressurize the drive fluid chamber 18. The pressure in the delivery fluid chamber 18 exerts pressure, via the piston 16, on the sample of fluid in the sample chamber 20. When the sample valve 22 is opened, the pressure in the sample chamber 20 drops. The pressure in the drive fluid chamber 18 drives the piston 16 to reduce the sample chamber 20 and to propel the fluid sample out of the sample container 12. In some cases, for example, where the fluid sample is crude oil at pressure under pressure, the fluid sample can become two phases (eg, liquid vapor) when the sample valve 22 is opened and the pressure inside the sample chamber 20 drops. The heavier liquid phase of the fluid sample is then accommodated around the bottom of the sample chamber 20, and the vapor phase of the fluid sample in the upper part of the sample chamber 20. The movement of the piston 16 ensures that the vapor and liquid phase of the fluid sample are expelled to the rest of the system 10. The driving fluid may be from a number of different sources. In the illustrative system 10, the drive fluid is pressurized gas stored in a can 26. The outlet of the can 26 may be of suitable size or a restriction may be provided around the outlet of the can 26 (Figure 1 describes a measuring valve, hereinafter referred to as "can valve 28") for measuring flow from can 26. In certain embodiments, can 26 is a standard C02 cartridge of 12 g, such as those used with energized handguns by C02. The standard C02 cartridge of 12 g can apply approximately a pressure of 8274 kPa to the chamber 18 of the drive fluid. Although described above using a drive fluid to evacuate the sample chamber 20, the fluid sample can be evacuated from the sample chamber 20 in other ways. For example, a mechanical or electromechanical system such as a motor and a gear train or screw drive can be used to move the piston 16. The outlet of the sample container 12 communicates with a restriction 32, such as a metering valve , which causes the sample of fluid released from the sample container 12 to ignite in a vapor phase in a liquid phase. Although a separate metering valve is described in Figure 1, restriction 32 may be other restrictions in the system. For example, in some cases restriction 32 may be valve 22 associated with sample container 12 or other variable or fixed orifice in system 10. The liquid phase is collected in a liquid accumulator 34 and the vapor phase continues to through the system 10. In certain embodiments, the liquid accumulator 34 can be cooled by a cooling element 35 to facilitate and / or increase the condensation of the liquid in the liquid accumulator 34. In the example of Figure 1, the cooling element 35 includes a Peltier effect device configured to be carried (for example, by aluminum fastener) and conductively transferring the heat with the liquid accumulator 34. In other embodiments, the cooling element 35 may be different, for example, the cooling element 35 may utilize an electric cooler, a chemical cooler or another device configured for one or more modes of heat transfer. In some cases, the cooling element 35 can be controlled by a temperature controller 37, to maintain the contents of the accumulator 34 of liquid at a substantially constant temperature. In certain embodiments, the liquid accumulator 34 includes graduations 36 that make it possible to visually determine the volume collected in the accumulator 34 of the liquid. The "dry" weight of the liquid accumulator 34 before the reception of the liquid phase can be measured accurately. The weight of the liquid phase can then be determined by measuring the weight of the accumulator 34 of liquid after receipt of the liquid phase and subtraction of the dry weight of the liquid accumulator 34. The density of the liquid phase can be determined by means of a manual densitometer. The volume of the liquid phase collected in the liquid accumulator 34 can be determined with reference to the graduation 36 or by dividing the weight of the liquid phase in the accumulator 34 between the density determined via the manual densitometer. In an example where the fluid sample includes crude oil under pressure or pressure, the volumetric shrinkage can be determined by comparing the volume of the liquid phase contained in the liquid accumulator 34, to the maximum volume, adjusted by the pressure and temperature, of the fluid sample in the sample container 12. In certain embodiments, the liquid accumulator 34 is a centrifugal tube that can be withdrawn from the system 10 and directly, without transfer of the fluid to another container, inserted inside a centrifuge device (not shown). In one example, where the fluid sample is crude oil under pressure, the liquid phase can include oil, water and entrained solids. The centrifugation of the liquid phase separates oil, water and solids and makes it possible to measure, for example, visually using graduations 36, the volume of oil, water and solids. The volume and weight of the liquid phase in the fluid accumulator 34 can be corrected for the water and sediments recovered during the centrifugation process, without the need to take another fluid sample. The vapor phase is communicated to a gas meter 38 which operates to measure the amount from the collected vapor phase. The gas meter 38, liquid accumulator 34 and restriction 32 may be contained in a common housing 46. In certain embodiments, the gas meter 38 is a floating piston gas meter having a graduated cylinder 40 that sealingly receives a piston. 42. In some cases, the piston 42 can be coupled additionally or alternatively to a graduated shaft (e.g., a plunger handle) extending from the cylinder 40. The receipt of the vapor phase in the graduated cylinder 40 displaces the piston 42, and the volume of the vapor phase can be visually determined from the graduations 44 on the cylinder 40 (or on the shaft, if so provided). The cylinder 40 can be purged, via a valve 45, before the receipt of the vapor phase to ensure accurate measurement. The temperature and vapor pressure in the gas meter 38 are monitored, so that the volume determined with the gas meter 38 can be corrected to the standard conditions. In certain embodiments, the temperature sensor 39, for example, a digital thermometer, may be provided to measure the temperature in the gas meter 38. In addition, in some cases, the temperature of the vapor in the gas meter 38 may be regulated . In the configuration of Figure 1, the gas meter 38 is heated by the heat output from the cooling element 35 (here, a Peltier effect device) to decrease the formation of the condensation of the gas meter 38. Other modes they can use a separate heating element, for example, an electric heating element, the Peltier effect device, the chemical heater or another device, to heat the gas meter 38 and, in some cases, that heating element can be controlled by the temperature controller 37 or other temperature controller to maintain the contents of the gas meter 38 at a substantially constant temperature. In addition, an insulating barrier 41 may be provided to substantially thermally insulate a portion of the system 10 from the rest of the system 10. In certain embodiments, the liquid accumulator 34, the restriction 32 and the related conduits are thermally insulated from the gas meter. 38 to reduce the heat communication from the cooling element 35 (or the separate heating element if provided) to the liquid phase of the sample. The gas meter 38 may contain an internal mixer. In one case, the internal mixer is a magnetic mixer. The internal magnetic mixer can be operated during or at the end of each steam collection cycle to ensure that the vapor contained in the gas meter is well mixed and uniform in composition. The housing 46 can have one or more lights to facilitate the operation of the system 10. For example, the lights can illuminate the liquid accumulator 34 and / or the phase meter 38, to help observe the respective fluid levels of each one. . The vapor phase of the fluid sample is distributed to a gas chromatograph 50. In certain embodiments, a conduit 48 extends between an outlet of the gas meter 38, and the gas chromatograph 50. In this way, the vapor phase is communicated directly to the gas chromatograph 50. The conduit 48 can be heated to reduce and / or minimize the formation of the condensate as the vapor phase is communicated to the gas chromatograph 50. A pump 52 can be provided for extract the vapor from the gas meter 38 to the gas chromatograph 50. In certain embodiments, the pump 52 is provided inside or as a component of the gas chromatograph 50. However, in other cases, the pump 52 may be provided outside of the gas chromatograph 50. The pump 52 is operable to extract a portion of the vapor phase to the gas chromatograph 50, and the gas chromatograph is operable to perform gas chromatography analysis of the vapor phase and the data of output indicating the composition of the vapor phase. In one case, the gas chromatograph 50 is Micro GC manufactured by Varian, Inc. The Micro GC is a small gas chromatograph that is designed to be easily transported and includes an internal pump that can operate as the pump 52. In certain embodiments , the gas chromatograph 50 can communicate with a computing device 54, such as a personal computer, a manual computer, or other computing device, to make possible the observation, analysis and manipulation of the data from the gas chromatograph. 50 or other components of the system 10. In certain embodiments, the computing device 54 is connected to a network 56 that allows the remote computing devices 58 to communicate with the computing device 54, and in some cases remotely operate the computer's chromatograph. gases 50. In certain embodiments, the computing device 54 may make it possible for a remote party to communicate with the system operator 10 to provide instruction to the operator regarding the operation of the system 10. In certain embodiments, the composition of the liquid phase can be analyzed with the gas chromatograph 50. Typically, gas chromatographs can only analyze gas vapor samples without additionally use an analytical separation column. However, by using a superior space technique, a gas chromatograph can be used to analyze the composition of the liquid phase. In general, in a superior space technique, a portion of the liquid phase is evaporated in the upper space of a sample bottle, and the vapor from the upper space of the sample bottle is analyzed with a gas chromatograph 50. In addition, of making possible the use of the gas chromatograph to analyze a composition of the liquid and gas phases, the superior space technique eliminates the need for temperature programming, and the assessment of the fast backflow to elute or eliminate the accumulation of excess components. high boiling point. An illustrative system 60 for performing the upper space technique with the gas chromatograph 50 is described in Figure 2. The illustrative upper space system 60 includes an adapter body 62 adapted to be coupled to the gas chromatograph 50. In the illustrative embodiment of 2, the adapter body 62 is received substantially within a housing 64 of the gas chromatograph 50. A threaded pin 68 of the body 62 extends through the housing 64 and threadably receives a nut 70. The nut 70 captures the housing 64 against a shoulder 66 of the adapter body 62, thereby securing the adapter body 62 to the housing 64. In other embodiments, the adapter body 62 can be configured to couple to the gas chromatograph 50 in a different manner, or it can reside separately from the chromatograph of gases 50.

The body 62 defines an internal cavity 72 of suitable size to receive a sample bottle 74. The sample bottle 74 includes a septum 76 that substantially seals its open end. In certain modalities, the septum is made of silicone. The body 62 supports a sampling needle 78 in the cavity 72 positioned to pierce the septum 76 and allow the sampling needle 78 to remove the vapor from within the sample vial 74, when the sample vial 74 is received by the adapter body 62. In certain embodiments, the sampling needle 78 is positioned to be withdrawn from a central area within the sampling vial 74. The body 62 further includes one or more heating elements 80 operated by a controller 82. The heating elements 78 heat the adapter body 62, which in turn heats the sample bottle 74 and its contents. In operation, a sample of the liquid phase is placed in the sample bottle 74. In certain embodiments, the liquid phase, such as oil, is applied as a thin film 84 on the inside of the sample bottle 74. In one case, the The amount of the liquid phase is approximately 5 μl and the sample bottle is approximately 25 cm3. The heating elements 78 are operated to heat the sample and cause a portion of the sample to evaporate (e.g., form a vapor in the upper space of the sample bottle 74). The controller 82 makes it possible for the heating elements 80 to be controlled to achieve a desired amount of heating to vaporize the liquid phase. The sampling needle 78 is coupled to the pump 52.

After a period of time to allow the sample to equilibrate, for example in about 5 minutes, the pump 52 is operated to remove a sample of the vapor from the headspace towards the analysis portion of the gas chromatograph 50. After this, the gas chromatograph 50 can be operated to determine a vapor composition of the upper space, which is representative of the liquid phase. In certain embodiments, the detection is performed by the thermal conductivity. The resulting peak areas are converted to a percentage basis by weight via external standard quantification. In certain embodiments, the upper space technique described above may also alternatively be performed by the solids. For example, the upper space technique can be performed on soil samples deposited in the sample bottle 74. The composition of the liquid sample can then be analyzed as follows. A small portion of the liquid sample is analyzed for the average molecular weight. For example, approximately 0.2 g can be analyzed via a freezing point method of benzene to determine molecular weight. The molecular weight is then mathematically combined with the weight percentage compositions derived from the upper space technique described above, to produce a compositional analysis on a base in mol percent. The individual mole percentage of each individual component up to isopentane is reported by this method. The hexanes to the pentadecane are grouped as individual pseudocomponents using the normal paraffins of each series as the pseudo-component cuts. The resulting pseudo components are converted to weight percent in a manner similar to that described above, while the mole percent of hexadecane and above is calculated from the material and the molar balance calculations. The resulting compositional analysis can thus report the liquid compositions expressed as a percentage by weight, percent by volume and mole percent. The composition of the liquid sample can then be combined with the compositional analysis of the gas sample using standard practices to produce a "pressurized" composition. The pressure composition can be used for computer model simulations to determine the behavior of the fluid phase and thus the property or assignment of the fluid.

One or more of the calculations described above may be performed by a computer, such as a computing device 54. The computing device 54 may incorporate dedicated software or generic software, for example, a spreadsheet, which facilitates the carrying out the calculations and / or the recording and storage of the resulting data. An illustrative method of analyzing the crude oil under pressure enabled by the illustrative system 10, is described with reference to Figure 3. In the illustrative method, a fluid sample is received in a sample container, such as a sample container 12. , in operation 110. The sample container can be evacuated before receiving the sample. In an example used for the sample container 12, the piston 16 can be moved to reduce the volume of the sample chamber 20 by pressurizing the chamber 18 of the delivery fluid. In some cases, the sample container is decoupled from the rest of the system and transported to the site in which the sample will be taken. The source of the sample can be purged, in some cases at least 100 ml are purged, before collecting the sample to reduce the probability of contamination in the sample. The fluid sample is then collected in a sample chamber of the sample container, and the pressure is allowed to stabilize in the sample chamber. If the sample container is so configured, the sample container and in some cases, two or more sample containers at a time, can be easily carried and handled by an operator. In step 112, the volume of the fluid sample in the sample container is determined. If the maximum volume of the sample chamber of the sample container is accurately known at a calibrated pressure and temperature, the volume of the sample can be determined by extrapolating the volume of the sample chamber 20 to the pressure and temperature of the sample chamber. the sample. The weight of the sample can be determined by weighing the sample container including the fluid sample in the sample chamber, and subtracting the dry weight of the sample container. In step 114, the fluid sample is separated into liquid and vapor phases. In some cases, the fluid sample is separated in the liquid and vapor phases, by igniting the fluid sample through a restriction. In one example using the sample container 12, the sample container 12 can be returned to the system 10, and the pressure applied to the delivery fluid chamber 18. The pressure can be maintained on the sample, and the sample fluid completely evacuated from the sample container as the volume of the sample chamber 20 is reduced, while the fluid sample leaves the container. In some cases, the liquid and vapor phases can be released through restriction at approximately 10 cm3 / second. In step 116, the liquid phase of the fluid sample is accumulated. In some cases, the liquid phase can be accumulated in a liquid accumulator which is also a centrifuge tube. In step 118, the liquid phase is centrifuged to separate the oils, water and solids. If the liquid phase were accumulated in a centrifuge tube, the liquid accumulator can be directly transferred to a centrifuge to perform the centrifugation operation. If the liquid phase is not accumulated inside a centrifuge tube, the contents of the accumulated liquid phase can be transferred to a centrifuge tube before the centrifugation operation. In step 120, the volume of the liquid phase is determined, for example, by reading the graduations on the centrifuge or the accumulator tube. The volume of the liquid phase can be corrected for water and solids, by subtracting the volume of water and solids from the total volume in the centrifuge tube or accumulator tube. The weight of the liquid phase in the centrifuge tube or accumulator can be determined by weighing the centrifuge tube or accumulator with the sample in liquid phase and subtracting the dry weight from the centrifuge tube or accumulator. In some cases, the inside of the sample container and other components of the system can be cleaned with cleaning cloths and the difference in weight of the cleaning cloths before and after use can be added to the weight of the liquid phase determined from the tube of centrifuge or accumulator to determine more precisely the total weight of the liquid phase. In step 122, the volumetric shrinkage of the fluid is determined. The volumetric shrinkage can be determined by comparing the volume of the liquid phase contained in the liquid accumulator 34 to the maximum volume, adjusted for pressure and temperature, of the fluid sample in the sample container 12. In step 124, it is determined the volume of the vapor phase. In one case, the vapor phase is communicated to a gasometer 38 that operates to measure the amount of vapor phase collected. In step 126 the composition of the vapor phase can be determined. In one case, the vapor phase is communicated to a gas chromatograph that performs chromatography on the vapor phase to determine its composition. In step 128, the composition of the liquid phase is determined. In one case, the composition of the liquid phase is determined using a superior space technique and the same gas chromatograph used in the determination of the composition of the vapor phase. In step 130, using the composition of the vapor phase in the composition of the liquid phase, the composition of the pressure can be determined. Although described in a particular order, the operations described above can be performed in a different order. Additionally, one or more of the steps may be omitted, or additional steps may be added. Although not necessary for the concepts described herein, the use of a gas chromatograph to analyze the composition of the vapor and liquid phase can eliminate the additional equipment used in the analysis of the liquid phase of the sample. In many cases, the additional equipment required to analyze the liquid phase is bulky and can not be maintained in small laboratory facilities. The team is also not easily transported. As a result, the equipment necessary to analyze the liquid phase of the sample, as well as the rest of the equipment necessary to analyze the sample, are maintained in centralized testing facilities in various sites around the world. A sample can travel tens or hundreds of kilometers from a site where it is taken, to the centralized test facility.

For example, although marine platforms typically maintain a small laboratory, the space on the platform does not allow the equipment necessary to analyze the liquid phase. Therefore, a sample taken on the marine platform could normally be transported to a test facility on the coast. Similarly, it is not practical to keep bulky analysis equipment at remote, coastal sampling sites, such as sites in rural areas. Depending on the location of the marine platform or the sampling site on the rural coast, the sample can travel tens or hundreds of kilometers to reach the test facilities. This trip introduces a lapse of many hours of the time the sample is taken, and the time in which the analysis can be made. This lapse of time discourages frequent testing and prevents repeated testing. The trip increases the probability that the sample will become compromised and / or contaminated and introduces additional expenses in the trip and in time to the costs of the analysis. If a sample is contaminated or soiled during collection, transport or otherwise, this will not be discovered until the sample has traveled the many kilometers to reach the centralized test facility. Another sample must then be taken and transported to the centralized test facility or the discarded analysis.

In contrast, a simple gas chromatograph, and especially a gas chromatograph, is configured for portability, is smaller, easily transported, and can be maintained in a small laboratory facility. In this way, the analysis system 10 can be maintained at or near the sampling site. For example, the analysis system can be maintained on a marine platform 100. Maintenance of the analysis equipment at the sampling site makes frequent testing possible, and eliminates the time frame and costs associated with transporting the sample. If it is not feasible to maintain the sample analysis equipment at the sampling site, the analysis equipment can be transported to the sampling site. Having the analysis equipment near the sampling site makes a new rapid test possible if the sample becomes contaminated during collection, transport or otherwise. In some cases, the complete system can fit inside two cases that can be handled by an operator without equipment, such as a crane or a forklift. Although not necessary for the concepts described herein, the system can be a continuous or quasi-continuous system that operates on a simple amount of the sample to analyze the composition and the other characteristics with little or no sample transfer between recipients. Systems that are not continuous or quasi-continuous may be a series of triggered tests, which require separate amounts of the sample for each analysis performed, and multiple transfers between vessels. The separate amounts of the sample for each and the inherently performed analysis require a larger volume of initial sample to extract intermediate sample quantities. In addition, there are sample losses as the residue is left over the various vessels between which the samples are transferred. In contrast, in the system described above, the sample collected in the sample container is continuously communicated through the system for analysis with only one transfer branch from the transfer to the upper space vial. If so configured, no other transfers are necessary. For example, the collection of the sample to be analyzed in the sample container, which also operates to evacuate the sample to the system and as a pyknometer eliminates multiple transfers, for example, between an intermediate sample container and the recipient. sample and between the sample container and a pyknometer. In another example, the accumulation of the liquid phase in a centrifuge tube eliminates the need for transfer between an accumulator and a centrifuge tube. In another example more, the released gas phase is taken from the liquid accumulator and communicated directly to the gas chromatograph without using a transfer container or flask. By operating on a simple amount of the sample to analyze the composition and other characteristics, the system is inherently more conservative of the amount of the sample used. Similarly, in a system that is located at or near the sampling site, few or no additional samples need to be collected for repeated testing because the additional sample can be quickly and easily collected. Therefore, a smaller amount of sample can be collected, making it possible to use a smaller sample container that is easier to transport between the sampling site and the rest of the system. Additionally, the use of a smaller sample container contributes to the reduced size and ease of transportation of the system. Also, because the entire sample in the sample container is used for analysis, no pumps are required to extract small amounts of the sample for use in a series of separate tests. A number of embodiments of the invention have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (22)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A method for analyzing a substance, characterized in that it comprises: separating the substance from a vapor phase and a liquid phase; determine a composition of the vapor phase with a gas chromatograph; depositing at least a portion of the liquid phase in a container; collecting a vapor from the upper space produced from the liquid phase in the container; and determine a composition of the vapor of the upper space with the gas chromatograph. The method according to claim 1, characterized in that it further comprises the heating of the liquid phase in the container to produce the vapor of the upper space. 3. The method according to claim 1, characterized in that collecting the vapor phase of the upper space from the container comprises sealingly coupling an entry of the gas chromatograph to the container, and extracting the vapor from the upper space towards the chromatograph of the container. gases The method according to claim 3, characterized in that the extraction of the vapor in the upper space towards the gas chromatograph, comprises the operation of a suction pump associated with the gas chromatograph. The method according to claim 1, characterized in that it further comprises the collection of a sample of the substance in a pycnometer, and wherein the step of separating the composition in a vapor and a liquid phase, is performed on the composition collected in the pyknometer. 6. The method according to claim 5, characterized in that it further comprises: determining a volume of the sample using the pycnometer; measure a volume of the separated liquid phase; and determining a volumetric shrinkage as a function of the volume of the sample and the volume of the liquid phase. The method according to claim 1, characterized in that the separation of the substance in a vapor phase and a liquid phase comprises the ignition of the compound and the collection of the liquid phase in a centrifuge bottle. 8. The method according to claim 7 characterized in that the substance comprises crude oil under pressure or pressure and the method further comprises centrifuging the liquid phase in the centrifuge bottle, to separate the oil, water and sediment in the liquid phase , and determine a volume of oil. 9. The method according to claim 1, characterized in that the vapor phase is communicated directly from a restriction to the gas chromatograph, the restriction causes phase separation. The method according to claim 1, characterized in that the determination of a composition of the vapor phase of the upper space with the gas chromatograph is carried out on a marine platform. 11. The method according to the claim 1, characterized in that it also comprises, after the separation of the vapor phase and the liquid phase, the heating of the vapor phase to reduce the condemnation thereof, and the cooling of the liquid phase to facilitate the condensation thereof. . 12. A system for analyzing a composition, characterized in that it comprises: a phase separator adapted to separate the composition into a vapor phase and a liquid phase; a gas chromatograph adapted to receive at least a portion of the vapor phase and perform a compositional analysis on the vapor phase; a container adapted to receive at least one liquid phase and contain a vapor of the upper space produced from the liquid phase in it; and an input coupled to the gas chromatograph, adapted to remove at least a portion of the vapor from the upper space from the container, and to the gas chromatograph, the gas chromatograph is adapted to receive at least a portion of vapor from the upper space and perform a compositional analysis on the vapor of the upper space. 13. The system according to claim 12, further characterized by comprising a heater adapted to heat the liquid phase in the container, to produce a vapor from the upper space. The system according to claim 12, characterized in that it further comprises a pump associated with the gas chromatograph, adapted to pump at least a portion of the vapor from the upper space in the gas chromatograph. 15. The system according to claim 12, characterized in that the phase separator separates the composition by differential pressure. The system according to claim 12, characterized in that it further comprises a sample container adapted to transport a sample of the composition between a source of the composition and the rest of the system, the sample container is adapted to operate as a pyknometer . 17. The system according to claim 12, characterized in that it further comprises a centrifuge tube in fluid communication with the phase separator, and adapted to accumulate the liquid phase therein. 18. The system according to claim 17, characterized in that it further comprises a cooler adapted to cool the centrifuge tube while it is operated to accumulate the liquid phase. 19. The system according to claim 12, characterized in that it resides on a marine platform. 20. A method to analyze crude oil under pressure, characterized in that it comprises: collecting a sample of crude oil under pressure or pressure from a production site; analyze a vapor phase of the sample with a gas chromatograph that resides at the production site; and analyze the liquid phase of the sample with the gas chromatograph. 21. The method according to claim 20, characterized in that the production site is a marine platform. 22. The method according to claim 20, characterized in that the analysis of a liquid phase of the sample, with the gas chromatograph, comprises the realization of a superior space vapor technique.