CA3065211A1 - A novel multidimensional gas chromatographic system for the compositional analysis of pressurized fluids with provision for an integrated single stage flash apparatus - Google Patents

Abstract

A novel Multidimensional Gas Chromatograph system is described that chromatographically separates and quantifies fixed gases such as, Nitrogen, Oxygen, Carbon Dioxide, Hydrogen Sulfide, light hydrocarbons comprised of Methane through N-Pentane and hydrocarbons in the Hexanes through C44 range. The system contains an integrated temperature programmable oven and an Isothermal External Oven.
The system utilizes packed and capillary chromatographic columns to achieve the desired separations. Detection of the "Light Ends" is accomplished using a TCD/FID in tandem arrangement. Heavier hydrocarbons (Hexanes trough C44) are separated on a series of capillary columns coupled to a Flame Ionization Detector. The system is equipped with a Single Stage Flash Apparatus for the physical determination of Gas to Oil Ratios (GOR) and Fluid Shrinkage (Shrink). Fluids ranging from sub ambient to 15,000 psig have been successfully analyzed.

Description

[0001] Field of the invention.

[0002] The present disclosure relates generally to the field of gas chromatography. The present disclosure relates more specifically to the use of a Novel Multidimensional Pressurized Gas Chromatography System. The Gas Chromatographic system described in this disclosure allows for the quantification of hydrocarbons in the -161.5 C (Methane) to 555 C (C44) range by Flame Ionization Detection (FID) with simultaneous quantification of Methane, Ethane, Propane, Iso-Butane, N-Butane, Nitrogen, Oxygen, Carbon Dioxide, and Hydrogen Sulfide by Thermal Conductivity Detection (TCD).

[0003] Background.

[0004] In the field of chemical analysis, the gas chromatograph (GC) has been a mainstay for chemists since the early 1950's. The basic gas chromatographic system as known in the art is shown in Figure 1 and includes seven functional units: a sample transfer line, a sample outlet, with a fine control metering valve, a regulated carrier gas supply, a programmable oven, a separation column, a detector for sensing the components of the column effluent and a data system for identification and quantification. In practice, a precisely measured sample is introduced through the sample valve which is vaporized within the GC inlet and mixed with a carrier gas prior to entry into the separation column.
The sample inlet may include a syringe/septum configuration or an injection system comprised of a liquid or gas sampling valve. The effluent of the separation column is attached to a suitable detector or detectors, and the analog signal of the detectors is converted to a digital signal using an AID converter. The digital converter sends the digitized information to a computerized data system for processing.

[0005] For High Pressure Fluids, present practice utilizes a high pressure (<5000 psig) precision injection valve such as shown in Figure 2 where the sample is vaporized within the valve prior to transport and entry of the GC sample inlet. The accuracy of sample size and the control of the sample temperature (control of vaporization) are both critical to accurate analysis. Detector readings, i.e., peak heights, peak areas and retention times, are evaluated in combination with sample size to identify components and determine the concentration of components within the sample fluid injected into the GC
inlet. Non uniform sample size directly affects final concentration calculations. Thermal wear and tear within the valve body can affect the precision machined slots and passages in the valve which carry the measured sample, thus, affecting the uniformity of sample size and reliability. Such wear is prone to causing leaks within the valve causing the seal between the valve body and polymeric rotor to fail. Those valves presently available are not well suited to temperature programming or isothermal operation above 325 C, thus limiting their use and application for fluids containing a wide range of components with boiling points ranging from minus 161.5 C (Methane) to 555 C (C44). Examples of typical Gas Chromatograph injection valves are displayed in Figures 3a, 3b, 4a, and 4b.
Figures 3a and 3b depict a four-port injection valve with fixed internal volume, shown in first position (a) and second position (b). Figures 4a and 4b depict a six-port injection valve 30 with external sample loop, shown in first (a) and second (b) positions. The operation of four-port, fixed internal volume and six-port, external loop injection valves are well understood.

[0006] For example, regarding the four port valve, referring to Figure 3a, in the first position (a) one port receives the carrier/mobile phase which then enters the valve, passes through a short segment of an internal channel (slot) and then exits out a second port to the column. A third port receives a sample stream which enters the valve, passes through a short segment of another internal channel (sample slot) and exits a fourth port to the vent/waste. When the valve is placed into its second position Figure 3b, a fixed volume of the sample stream (-0.5 micro liters) (previously contained within the sample slot) is now urged by the carrier/mobile phase stream to move into the column.

[0007] Regarding the six port valve, referring to Figure 4 a, in the first position, one port receives the carrier/ mobile phase which then enters the valve, passes through a short segment of an internal channel (slot) and then exits out a second port to the column. A
third port receives a sample stream which enters the valve, passes through a short segment of another internal channel (sample slot) and exits a fourth port into a length of fixed volume external sample loop to a fifth port where it reenters the valve and passes through a short segment of an internal channel (slot) and then exits out a sixth port to the vent/waste. When the valve is placed into its second position Figure 4b, a fixed volume of the sample stream (previously contained within the external sample loop) is now urged by the carrier/mobile phase stream to move into the column.

[0008] Temperature control is also critical to the successful analysis of the sample fluid in any GC apparatus. The temperature of the sample at the inlet and body of the injection valve must be kept low enough to prevent pre-volatilization of the sample material. The "captured" sample can vary from an "ideal" homogenous sample, to a two phase sample that is not representative of the original sample composition; thus, pre-volatilization creates non-uniform sample sizes and yields inaccurate results. After injection, the temperature of the valve body must be increased to vaporize the heavier (higher boiling) sample components prior to entry into the gas chromatograph's injection port.
The outlet of the valve and the transfer line between the valve and sample inlet must be maintained within a desired temperature range in order to prevent inadvertent condensation of the sample after it has been volatilized. Condensation can prevent the system from functioning correctly, leading to erroneous results. Condensed material may remain in the sample body and/or transfer line rendering present and future measurements inaccurate as well.

[0009] Numerous devices are marketed to provide injection valve arrangements for chromatographic devices. Sampling valves are generally either rotary valves or push-pull valves. Those marketed by Valco Instruments Co., Inc. (Houston, Texas) are representative of the types of prior art valves currently available in the market. Insulated heated valve enclosures are combined with the valve, and sometimes the sample inlet, to control the temperature of the valve and sample independently of the column temperature. These heated valve enclosures are ovens or mandrels, are placed over or around the body of the valve or connected to the GC inlet and connected to a source of current to heat the resistive elements within the valve oven or valve body.
Sensors must be employed on these independent heater elements to monitor and adjust the temperature of the valve body to avoid overheating the valve body with the sample enclosed.

[0010] Figure 5 shows a prior art four-port valve with heating collar. In this valve, there is a cylindrical heater element inserted within a sleeve which is wrapped around the valve body. This valve comprises heating collar, power lines to the heater cartridge, a valve body, an actuator standoff, thermocouple leads, and thermocouple and rotor torsion adjustment. After injection, the heated collar is temperature programmed to raise the valve body temperature to the point the fluid contained within exits as vaporized fluid.

This approach is limited to samples <5000 psig. However, because the valves are temperature programmed to volatize the sample and its components, they are prone to frequent failures and leakage which can cause an unsafe flammable/explosive conditions.
BRIEF SUMMARY OF INVENTION

[0011] Disclosed are details of a Multidimensional Gas Chromatographic System capable of analyzing sub ambient (-400mm Hg) and high pressure (<20,000 psi) with single injection of a fluid (gaseous or liquid) sample.

[0012] The system utilizes simultaneous detection of "Light Ends" such as but not limited to Nitrogen, Oxygen, Carbon Dioxide, and Methane though Normal Pentane hydrocarbons by using a Thermal Conductivity Detector (TCD) in series with a Flame Ionization Detector (FID).

[0013] The described system also allows for the detection, identification and quantification of "Heavy Components" ranging from Hexanes to C44. A three port stream selection valve is used to move these "light Ends" from a capillary pre column to an External Iso Thermal oven containing a six port injection valve where the sample loop is replaced with a "Light Ends Trap" the Stream select valve is advanced and the pre column is effectively "blocked in" to isolate and "park" the Hexanes and heavier components.

[0014] Once N-Pentane has eluted from the packed column the stream select valve is advanced to bring the pre column and analytical column in series. The programmable oven temperature ram begins and the Hexanes and heavier components begin to elute in a boiling point fashion and are detected and quantified by the FID.

[0015] In one embodiment, there is described a high pressure injection (HPLC) valve shown in Figure 6 to facilitate the isolation and injection of a precise fixed volume of sample fluid into a flowing stream of carrier gas.

[0016] The outlet of the injection valve is connected to the pre column by using a ¨12"
stainless steel capillary with a internal diameter of ¨0.17mm.

[0017] Use of a temperature programmable on-column Gas Chromatograph inlet to facilitate vaporization and mixing of the sample fluid with the carrier gas.
The carrier gas can be those typically used in gas chromatography such as Helium, Hydrogen, Nitrogen, and Argon to name a few.

[0018] Also described is a method of sampling and injection of a high pressure fluid near to bubble point or dew point conditions.

[0019] Use of high pressure methane (introduced via methane padding the transfer line) is described to "pad" the line between the sample line or vessel and the injector to avoid the possibility of the fluid retrograding or dipping below the bubble point upon sample transfer.

[0020] In one embodiment, there is disclosed a multidimensional gas chromatography system for analyzing a sample comprising: a temperature programmable oven; an external Isothermal oven; a chromatographic pre separation column located in the oven to separate components of interest capable of receiving the sample, the column having first and second ends; a sample inlet external to the oven in fluid communication with the column first end for introducing the sample into the separation column; a detector in fluid communication with the column second end capable of detecting the sample, or a component thereof, as the sample or component thereof moves there through; a carrier gas flowing from the inlet, through the column and through the detector capable of urging the introduced sample to move from the inlet through the column and through the detector; a data system capable of collecting a digital signal from the detector, displaying the data as a series of peak heights and peak areas, and analyzing the data to perform data integration for the purpose of quantification by peak areas and identification by peak retention times; a low dead volume inline filter; a length of high pressure tubing to facilitate mixing; a small ID (-0.17mm) tubing to increase linear velocity and volumetric sweep of the sample chamber and transfer line. The restrictor having an inlet end and an outlet end; a chromatographic column connected to the restrictor line in an On-Column manner with low dead volume fittings.

[0021] The sample injection valve may further comprise an internal fixed volume or an external fixed volume sample loop. The detectors may be selected from the group consisting of: Flame Ionization Detector (FID) or Thermo Conductivity Detector (TCD).

[0022] There is also described a gas chromatography system for analyzing a sample comprising: (a) a temperature programmable oven; (b) a chromatographic separation column located in the oven to separate components of interest and being capable of receiving there through a sample to be analyzed, the column having an inlet end and an outlet end; (c) a detector operatively coupled to the outlet end of the column for analyzing the sample or the separated components of the sample and capable of generating a digital signal; and an injection valve located outside the oven.
The injection valve comprises a carrier phase stream inlet for receiving a carrier phase stream, a carrier phase stream outlet, a sample stream inlet and a sample stream outlet. The injection valve is capable of operating in a first position establishing fluid communication between the carrier stream outlet and the column inlet to permit the carrier phase to travel through the column and detector, and receiving and directing a stream of the sample through a valve sample inlet, through a sample collection pathway defining a volume of sample aliquot, and then out a valve sample outlet to a vent or waste location. The injection valve is also capable of operating in a second position introducing the sample aliquot into the carrier phase to permit the carrier phase to urge the sample aliquot through the column and detector. The injection valve is preferably capable of operating leak free from sub ambient conditions to pressures exceeding 20,000 psi at temperatures slightly above ambient. The injection valve further comprises a length of capillary high pressure tubing to facilitate mixing of the sample aliquot with the carrier phase, the high pressure tubing comprising a first end connectable to the valve carrier phase outlet and a second end connectable to the column inlet, the second end of the high pressure tubing further comprising a narrow bore flow restrictor. The system further comprises (e) a data system capable of collecting the digital signal from the detector, displaying the data as a series of peak heights and peak areas, and analyzing the data to perform data integration for the purpose of quantification by peak areas and identification by peak retention times.
In one embodiment, the sample injection valve is a four port valve.

[0023] In another embodiment, the sample injection valve sample collection pathway comprises an internal fixed volume slot. In this embodiment, the injection valve is capable of receiving and directing, in the first position the stream of the sample through the valve sample inlet, through the fixed volume sample slot, and out the valve sample outlet to a vent or waste location, the injection valve also capable of, in the second position, of introducing the fixed volume sample aliquot into the carrier phase.

[0024] The sample injection valve may further comprise an external fixed volume sample aliquot loop.

[0025] In another embodiment, the sample injection valve is a six port valve.
In this embodiment, after the sample injection valve, in its first position, directs the sample stream out of the valve sample outlet, the sample is then directed through an external fixed volume sample loop defining a larger volume sample aliquot, into a second valve sample inlet, through a second fixed volume sample slot within the injection valve, and out the valve sample outlet to the vent or waste location.

[0026] The gas chromatography systems described herein may utilize known detectors, such as those selected from the group consisting of: Flame Ionization (FID) or Thermal Conductivity Detector (TCD), Mass Spectrophotomer (MS), or any suitable Gas Chromatograph (GC) detector.

[0027] The gas chromatography system may also include an in-line filter installed between the valve carrier phase exit and the narrow bore transfer line.

[0028] A gas chromatography system for analyzing a sample is also disclosed comprising: a temperature programmable oven; an Isothermal Oven with packed chromatographic separation columns located in both the external isothermal oven the oven to separate components of interest and being capable of receiving there through a sample to be analyzed, the columns having an inlet end and an outlet end;

[0029] a detector operatively coupled to the outlet end of the columns for analyzing the sample or the separated components of the sample and capable of generating a digital signal; a four port injection valve located outside the oven, the injection valve capable of receiving and directing, in a first position, a carrier phase stream into a carrier phase inlet of the valve, through an internal carrier phase slot within the valve, through a carrier phase valve outlet, into the column inlet, through the column, out the column outlet and through the detector, and also receiving and directing a stream of the sample through a valve sample inlet, through a fixed volume sample slot within the injection valve defining a sample aliquot, and out a valve sample outlet to a vent or waste location, the injection valve also capable of, in a second position, introducing the sample aliquot into the carrier phase to permit the carrier phase to urge the sample aliquot through the carrier phase valve outlet, into and through the column, and into and through the detector, the injection valve capable of operating leak free from ambient conditions to pressures exceeding 20,000 psi at temperatures slightly above ambient, the injection valve further comprising a length of high pressure narrow bore tubing to facilitate mixing of the sample aliquot with the carrier phase, the high pressure tubing comprising a first end connectable to the injection valve carrier phase outlet and a second end connectable to the column inlet, the second end of the high pressure tubing further comprising a narrow bore tubing; an in-line filter installed between the valve carrier phase exit and the transfer line; a data system capable of collecting the digital signal from the detector, displaying the data as a series of peak heights and peak areas, and analyzing the data to perform data integration for the purpose of quantification by peak areas and identification by peak retention times.
100301 In another embodiment, a gas chromatography system is disclosed for analyzing a sample comprising: a temperature programmable oven; a chromatographic separation column located in the oven to separate components of interest and being capable of receiving there through a sample to be analyzed, the column having an inlet end and an outlet end; a detector operatively coupled to the outlet end of the column for analyzing the sample or the separated components of the sample and capable of generating a digital signal; a six port injection valve located outside the oven, the injection valve capable of receiving and directing, in a first position, a carrier phase stream into a carrier phase inlet of the valve, through an internal carrier phase slot within the valve, through a carrier phase valve outlet, into the column inlet, through the column, out the column outlet and through the detector, and also receiving and directing a stream of the sample through a first valve sample inlet, through a first internal fixed volume sample slot within the injection valve, into an external fixed volume sample aliquot loop, back into the valve and through a second internal fixed volume sample slot within the injection valve, and then out a valve sample outlet to a vent or waste location, the injection valve also capable of, in a second position, introducing the external fixed volume sample aliquot into the carrier phase to permit the carrier phase to urge the sample aliquot through the carrier phase valve outlet, into and through the column, and into and through the detector, the injection valve capable of operating leak free from ambient conditions to pressures exceeding 20,000 psi at temperatures slightly above ambient, the injection valve further comprising a length of high pressure tubing to facilitate mixing of the sample aliquot with the carrier phase, the high pressure tubing comprising a first end connectable to the valve carrier phase outlet and a second end connectable to the column inlet, the first end of the high pressure tubing further comprising a flow restrictor; an in-line filter installed between the valve carrier phase exit and the flow restrictor; a data system capable of collecting the digital signal from the detector, displaying the data as a series of peak heights and peak areas, and analyzing the data to perform data integration for the purpose of quantification by peak areas and identification by peak retention times.
100311 Also disclosed is a multidimensional gas chromatography method as outlined in Figures 7 and 8 using a Gas Chromatograph, described valve diagrams, and injection systems for the separation and detection of Methane trough C44 with simultaneous quantification on both TCD and FID. The system described herein is comprised of the following; a capillary pre column for isolation and transfer of methane though pentane as well as fixed gases such as nitrogen, oxygen, carbon dioxide and hydrogen sulfide. The outlet of the pre column is attached to a three port stream selection valve that diverts the "lights ends" (Cl to C5 plus N2, CO2, and H2S) to a six port gas injection valve. These "light ends" are trapped in the six port valve sample loop/trap which are then injected into the packed columns contained in the external isothermal oven. At a predetermined time the "light ends are injected into the packed column and the 3 port stream select valve is advanced one step to block in the Hexanes Plus components. Once the light ends have been injected on to the packed column system which separates Nitrogen, Methane, Carbon Dioxide, Ethane, Hydrogen Sulfide, Propane, Iso-Butane, N-Butane, Iso-Pentane and N-Pentane. These components first pass through the non destructive TDC
detector and then through the FID. In this sense all light components are detected and quantified using the TCD digital output, these same components are then routed to the FID
which detects Methane, Ethane, Propane, Iso-C4, N-C4, Iso-05 and N-05. Once N-05 has been detected on the FID the stream select valve is advanced one step which then joins the pre column and analytical column in series. Flow is then reestablished though both capillary columns and the oven temperature program is started. The oven is temperature programmed from 40 C to 350 C at a rate of 15 to 25 C per minute. The oven program allows for the separation of Hexanes through C44 in a boiling point manner.
The FID
detector is operatively coupled with the analytical column outlet end for analyzing a sample that has passed through the (a) analytical column and generating corresponding digital data output, and a data system for collecting and displaying the data, (b) providing a narrow bore transfer line to increase linear velocity and volumetric sweep of the components from the injection valve to the separation systems described herein (c) optionally providing an in-line filter upstream of the transfer line for filtering the sample, (d) purging the column with carrier phase when the injection valve is operating in a first mode of operation, (e) directing sample through a sample aliquot collection zone of the injector during the injection valve first mode of operation, (f) injecting the sample aliquot into the carrier phase when the injection valve is operating in a second mode of operation, and (g) detecting the sample with the detector.
[0032] In another embodiment, a gas chromatography analytical method is disclosed comprising the steps of: providing a gas chromatography system as described herein for analyzing a sample; connecting a sample inlet tubing from a sample vessel tubing to the injection valve sample, the sample inlet tubing being insulated and temperature controlled, a sample inlet employing a metering valve; regulating the temperature of the sample in the sample tubing; placing the injector valve into the load position, and opening slightly the sample inlet metering valve; closing the metering valve to block in the system maintaining the sample fluid in a single phase; opening the sample valve to allow the fluid to be in communication with the gas chromatograph; during sample transfer, maintaining the sample fluid at constant temperature and pressure to avoid vaporization or condensation of the sample fluid; using the sampling system's metering valve, slowly purging a small amount of sample (-2 cc) to inventory the sample transfer line and the sampling system's injection valve; placing the injection valve into the "Inject" position thus allowing the valve's internal cavity or external sample loop to be placed in line with the carrier gas; simultaneously, pressing the start button on the gas chromatograph to start data collection which simultaneously starts the GC oven temperature program; closing the sample valve and opening the sample metering valve to flash any fluid that remains in the sample transfer line; permitting the gas chromatograph to run to completion; processing the data in a manner consistent with industry accepted practices of peak area integration and component identification; and evaluating detector readings, i.e., peak areas and retention times, in combination with sample size to identify components and determine the concentration of components within the sample fluid injected into the GC inlet. This GC method may further comprise pre pressurization of the sample transfer line with a suitable, before the step of opening slightly the sample inlet metering valve, thus "padding" the transfer line between the sample vessel and the gas chromatograph with technical grade methane or other suitable fluid at a pressure equal to that of the sample fluid in order to reduce the effect of a liquid flashing, or allowing a gas to retrograde when the sample valve is opened. Additionally, when the sample is a liquid, the step of regulating the temperature of the sample may further comprise maintaining the sample temperature slightly below the bubble point temperature of the sample fluid, and wherein the sample is a gas, the temperature should be maintained slightly above the dew point temperature of the sample.
DETAILED DESCRIPTION OF THE INVENTION
10033] To overcome the deficiencies in prior practices, the present disclosure provides a high pressure HPLC style injection valve fitted with a narrow bore sample transfer line, which can repeatedly and accurately capture a precise, measured amount of sample from a sample stream or sample vessel, manipulate and maintain the temperature and pressure, as necessary, and deliver a homogenous sample to the GC inlet or directly on column.
The objective is to transfer a representative portion of sample to a multidimensional chromatographic system comprised of capillary and packed columns which are contained in a gas chromatograph equipped with External Isothermal oven and a temperature programmable oven and suitable detectors which are typically a Flame Ionization Detector ("FID") and Thermal conductivity ("TCD"). The analog output of the detector is connected to an analog to digital interface that then sends the digitized signal to a computerized GC data system for identification, integration and quantification of the components of interest.
100341 The present disclosure relates to a fluid injection system adapted for use with a gas chromatograph; specifically, to a valve providing direct entry to the chromatograph inlet or directly on column without pre volatilization, programmed heating or post-injection cooling of the sample valve.
100351 In the present disclosure, high pressure liquid chromatography ("HPLC") valves are used to inject a small aliquot (0.006 to >1 micro liters) of the sample into a flowing steam of a carrier gas.
100361 Exemplary 4-port and 6-port valves are depicted in Figures. 3a, 3b, 4a, 4b. in both cases the valve of choice would receive flow or pressure controlled carrier/mobile phase. The subsequent "sample and carrier mixture" being effectively mobilized and moved from the valve's sample cavity or sample loop into short length narrow bore tubing. The outlet of the narrow bore line can be physically inserted into a typical packed column inlet, split/splitless inlet, or coupled directly to a chromatographic column in a "direct on column" fashion. In each case, the sample components are quantitatively transferred from the injection valve to multidimensional separation system as previously described. The quantification and detection system can comprised of a variety of detectors of choice, e.g., FID, thermal conductivity detector ("TCD"), mass spectrophotometer ("MS") or any conventional gas chromatography ("GC") or HPLC

detectors. Such a system is well suited for the analysis of high pressure, high boiling mixtures such as, but not limited, to reservoir fluids, e.g., crude oil, gaseous phases, waxes, gels and emulsions.
100371 For example, regarding the four-port HPLC valve, having valve body, and referring to Figures 3a and 3b, when in the valve handle is its first position (Figure 3a), one valve port receives the carrier/ mobile phase from carrier gas inlet tubing, the carrier/mobile phase then enters the valve, passes through a short segment of an internal channel (slot) and then exits out a second valve port into a transfer line or carrier gas outlet tubing where the sample/mobile phase is then directed to the multidimensional chromatographic separation system. A third port in valve receives a sample stream from sample inlet tubing (coming from the sample transfer line) which delivers sample into the injection valve. The sample then passes through a short segment of another internal channel (sample slot) and exits through a fourth valve port to the sample outlet tubing which is directed to vent/waste sample outlet. When the injection valve is placed into its second position (Figure 3b), a fixed volume of the sample stream (previously contained within the sample slot) is now urged by the carrier/mobile phase stream to move into the carrier gas outlet tubing segment to the separation system.
[0038] This carrier/mobile phase outlet tubing segment further comprises a short length of narrow diameter tubing, such as 1/32" stainless steel tubing. This tubing has an inlet end and an outlet end. It is preferable to have this short (-12") segment of tubing be of a flexible nature to permit bending to make the connection between the valve and the GC
inlet or column, hence the preference for small diameter tubing. This tubing has a 1/32"
inlet opening and a 0.17mm outlet opening. The tubing also has proximate the outlet end a standard ferrule type threaded connection comprising threaded tubing connector and ferrule. The narrow bore tubing further comprises a shoulder at its opposite end, the shoulder capable of receiving and holding in place a small in-line filter, such as a stainless steel porous frit (e.g., those provided by Valco, such as those with a 0.5 micron pore size or other desired pore size). Although the system can operate without the in line filter, it is preferred to utilize the in line filter to reduce chances of having particulates, dust, asphlatenes, corrosion byproducts, or the like can plug the narrow bore tubing.
Given that this connection will be subject to high pressures, it is also preferable to employ a ferrule made of a material that will resist seizing, such as stainless steel gold plate.
[0039] Regarding the six port valve with its valve body, sample loop and valve body stator, and referring to Figures 4a and 4b, when the valve handle is in the first position (load), the injection valve receives the carrier/mobile phase via port via carrier inlet tubing. The carrier/mobile phase then enters the valve, passes through a short external loop of the valve and then exits out a port (carrier outlet/column). The injection valve receives a sample stream via the sample transfer line which enters the valve, passes through a short segment of another internal channel and exits through a port connection into a length of fixed volume external sample tubing loop to a port where it reenters the valve and passes through a short segment of an internal channel (slot) and then exits out Port 2 connection to the sample outlet tubing through a fine control metering valve and on to the vent/waste line. When the valve is placed into its second position (Inject), a fixed volume of the sample stream (previously contained within the external sample loop) is now urged by the carrier/mobile phase stream to move into the column.

[0040] The system further preferably comprises a low dead volume inline filter to remove particulates and insoluble materials such as asphlatenes. A length of high pressure tubing is also provided to facilitate mixing. There is also provided a narrow bore tubing inserted into a GC inlet (packed or Split/Splitless) or connected directly to the outlet narrow bore tubing in an On-Column manner. The system also comprises a gas chromatograph comprised of sample inlet, chromatographic separation columns to separate components of interest, a temperature programmable oven and suitable detectors, such as but not limited to Flame Ionization (FID) or Thermal Conductivity Detector (TCD). A data system is also provided capable of collecting a digital signal from the system's detectors and integration capabilities to produce peak heights and peak areas for the purpose of quantification by peak areas and identification by peak retention times.
[0041] The GC Split/Splitless inlet comprises, e.g., a silicone rubber septum with septum cap for receiving the outlet end of the narrow bore tubing. The inlet is further comprised of a septum purge line, and a split vent line, injector liner, an insulated inlet body containing a heating cartridge and thermocouple for temperature control.
[0042] The present disclosure provides an improvement over existing GC
injection systems due to the fact that geometry of the HPLC style valve coupled with the use of a narrow bore capillary transfer line negates the need to apply heat in order to vaporize or move the sample fluid from the injection valve to the column inlet or inlet splitter.
[0043] The system of the present disclosure avoids the necessity of enclosing the valve body in an oven with the attendant complications of thermocouples and temperature measurement circuitry to control the heat necessary to vaporize the sample.
Instead this system provides quantitative transfer of the sample fluid from the injection valve to the GC inlet 6, or directly on column at ambient temperatures.
[0044] Operation of the System [0045] The top portion of the valve body adjacent to the inlet port may be maintained at ambient or near ambient temperature. This prevents pre-vaporization of the sample before it reaches GC inlet or GC column. As the sample is moved to the inject position, the sample is "mobilized" carrier gas and swept into the GC inlet interface or directly on column by the injectant/carrier gas. Using a conventional split inlet allows the sample to be concentrated on the column by established temperature splitter management techniques and introduced into the column by the continued flow of carrier gases such as but not limited to Helium, Nitrogen, Argon, and Hydrogen. Temperature programming of the column, allows separation of components in the C6 to C44 range without heating the sample injection valve.
[0046] Utilizing the increased linear velocity and volumetric sweep of the carrier gas allows the "sample" to be introduced in a homogenous manner to the GC column, avoiding sample discrimination, and thereby obtaining clear, high definition chromatograms throughout a wide molecular weight range. In addition, this invention allows for accurate analysis of gasoline, diesel fuels, crude oils, condensates, and vacuum gas oils without any pre-volatilization caused by the application of external heat to the injection valve.
[0047] Figure 9 (top Chromatogram) shows a chromatogram of the packed column system contained in the external oven and the respective detector outputs i.e.
TCD and FID. The chromatograms clearly show baseline separation of all "Light Ends"
contained in the sample fluid. Figure 9 (bottom Chromatogram) show the chromatographic separation FID detection of Hexanes through C44. The pre column used was a Restek MTX capillary with a 0.53mm ID, boiling point column with a length of 30 meters and 1.5 micron film thickness. The packed column used was a 1/16" OD X 0.04"ID,

30' in length packed with 30 wt% DC200/500 on Chromsorb 80/120 mesh PAW. The Analytical column was a Restek MTX 0.53mm ID, boiling point column with a length of 30 meters and 1.5 micron film thickness. A four port HPLC style liquid injection valve was used with an internal volume of 0.32 micro liters. The chromatogram below spans from 0 to 60 min. A flame ionization detector (FID) was used for detection and integration and quantification was accomplished using ChromPerfect chromatography software. The sample fluid was a normally occurring "Black Oil", with an API
gravity of 33.70. The chromatogram displayed used the method of "baseline subtraction" to eliminate interferences from column bleed. The displayed chromatogram is annotated at every 5 normal paraffins intervals from Cl to C40. Regarding Figures 9a and 9b, the Y
Axis = Detector response in Mv, the X Axis = Time in minutes, Programmable Oven Profile = Initial Temp = 40 C, hold for 12.5 min, program oven temp at 15 C to 350 C, hold for 25 min Detection ¨ Flame Ionization (FID) with baseline subtraction.
The External Oven is operated in an Iso thermal manner @ 130 C, packed column carrier Gas ¨15 cc/min at 95 psi with Thermal conductivity Detection (TCD).
[0048] In another embodiment, the present disclosure is directed to the use of a length of micro bore high pressure tubing with outer diameters ("OD") ranging from 1/32"
to 1/16"
with inner diameters ("ID") ranging from 0.005" to 0.001". The length of tubing is used to connect the injection valve to the GC inlet and is kept at a nominal length (-12") to reduce unnecessary dead volume between the injection valve and the injector body. An inline micro fine filter is inserted between the exit of the sample injection valve and the entrance to the GC inlet or column to prevent plugging from particulates in the sample fluid or from the precipitation of insolubles such as asphlatenes.
[0049] The GC systems as described above can be employed with typical gas chromatography analytical methods.
[0050] For example, in one method, the sample outlet of the sample vessel (Sample Cylinder, PVT Cell or Down Hole Tool) is connected to the inlet of the high pressure SCF injection valve using a short (¨ 3') length of transfer tubing that is insulated and temperature controlled. In the case of a liquid sample, the temperature should be held slightly below the bubble point temperature of the sample fluid. In the case of a gas the temperature should be maintained slightly above the dew point temperature of the sample fluid. The injector valve is turned (e.g., clockwise) to the "load" position.
A metering valve is employed with the sample inlet and this metering valve is opened slightly. One can then "pad" the transfer line between the sample vessel and the gas chromatograph with technical grade methane or other suitable fluid at a pressure equal to that of the sample fluid in order to reduce the effect of a liquid flashing, or allowing a gas to retrograde when the sample valve is opened. The metering valve is then closed to "block in" the system keeping the sample fluid contained in a single phase. The sample valve is opened to allow the fluid to be in communication with the gas chromatograph.
During sample transfer the sample fluid should be maintained at constant temperature and pressure to avoid vaporization or condensation of the sample fluid.
[0051] Using the sampling system's metering valve, a small amount of sample (-2 cc) is slowly purged to inventory the sample transfer line and the sampling system's injection valve. Next, the injection valve is turned (clockwise) to the "Inject"
position thus allowing the valve's internal cavity or external sample loop to be placed in line with the SCF miscible injectant. Simultaneously, the start button is pressed on the gas chromatograph to start data collection which simultaneously starts the GC oven temperature program. The sample valve is then closed off and the sample metering valve is opened to flash any fluid that remains in the sample transfer line. The gas chromatograph is permitted to run to completion and the data is then processed in a manner consistent with industry accepted practices of peak area integration and component identification. Detector readings, i.e. peak areas and retention times, are evaluated in combination with sample size to identify components and determine the concentration of components within the sample fluid injected into the GC
inlet.
[0052] Integrated Gas to Oil Ratio (GOR) Apparatus [0053] In the high-pressure reservoir, fluids exist for the most part, in one phase. Upon exiting the well, the phases dissociate and therefore must be transported separately.
Therefore, the effluent hydrocarbons from the well head pass through a set of separators at different pressures which yield the optimum economical recovery of liquid and gaseous hydrocarbons; in an oil field, this equates to maximizing the produced liquid volume, i.e. minimizing the oil formation volume factor (Bo) and Gas-Oil-Ratio (GOR);
the opposite being true for a gas field. The described Integrated GOR
Apparatus accurately replicates a single Stage Flash, the results of which can also be utilized to validate theoretical models.
[0054] The GOR apparatus displayed in Figure 10 is capable of measuring the gas-oil ratio of pressurized fluid samples at standard conditions. The system comprises a ¨10cc pycnometer, a liquid trap, a gas outlet line that passively channels the flashed equilibrium gas from the liquids separation vessel through the Gas Chromatograph's injection valves and then on to a digital flow meter. In practice a pressurized fluid is transferred under pressure from a sample cylinder or PVT cell into a high pressure pycnometer of known volume. The weight of the pycnometer, empty and full is determined by placing the pycnometer on a three place balance. The density of the transferred fluid is then calculated from the mass of the fluid transferred to the pycnometer and the volume of the pycnometer. The captured fluid is allowed to "flash" to ambient conditions (typically 20 and one atmosphere) upon which the fluid separates into two distinct phases i.e.
equilibrium gas and equilibrium liquid. After the all the fluid in the pycnometer has been flashed, the total gas volume is read from the gasometer, while the dead oil volume is determined by knowing the weight of the equilibrium liquid and its specific gravity or density. The ratio of recovered volume of gas and liquid at standard conditions s are used to calculate the fluids GOR while the fluids shrinkage is determined by comparing the initial volume of liquid to the final recovered volume of liquid.
BRIEF SUMMARY OF DRAWINGS
[0055] Figure 1 depicts a schematic view of a typical prior art gas chromatographic system.
[0056] Figure 2 depicts a previous art four port injection valve.
[0057] Figure 3a depicts an example of typical prior art Gas Chromatograph injection valve, shown here as a four-port injection valve with fixed internal volume, in a first position A.
[0058] Figure 3b depicts an example of typical prior art Gas Chromatograph injection valve, shown here as a four-port injection valve with fixed internal volume, in a second position B.
[0059] Figure 4a depicts an example of typical prior art Gas Chromatograph injection valve, shown here as a six-port injection valve, with external sample loop, in a first position A.
[0060] Figure 4b depicts an example of typical prior art Gas Chromatograph injection valve, shown here as a six-port injection valve, with external sample loop, in a second position B.

[0061] Figure 5 shows a prior art four-port valve with heating collar or cylindrical heater element inserted within a sleeve which is wrapped around the valve body.
[0062] Figure 6 shows a High Pressure Injection Valve coupled to a Hp5890 Series II
split/splitless inlet.
[0063] Figure 7 and 8 details the configuration of the Multidimensional Gas Chromatographic system described herein.
[0064] Figures 9a and 9b are chromatograms of the packed column with TCD
[0065] Figure 10 shows the addition of an integrated External Flash Apparatus for the physical measurement of Gas to Oil Ratio (GOR) and Fluid Shrinkage ( Shrink Factor) [0066] References:
[0067] The following represents an exemplary list of U.S Patent references:
[0068] U.S. Patent 3120749 (Paglis etal.) (1964-02-11) entitled: "Gas Chromatography".
[0069] U.S. Patent 3559703 (Maul et al.) (1971-02-02) entitled "Fluid sample injector for gas chromatograph".
[0070] U.S. Patent 3889538 (Fingerle) (1975-06-17) entitled "Sample vaporizer for gas chromatography".
[0071] U.S. Patent 4429584 (Beyer et al.) (1984-02-07) entitled "Microprocessor controllable automatic sampler".
[0072] U.S. Patent 9234608 (Stearns et al.) (2016-01-12) entitled "Heated rotary valve for chromatography".
[0073] U.S. Patent 9316324 (Berndt) (2016-04-19) entitled "Shear valve with silicon carbide member.
[0074] All references referred to herein are incorporated herein by reference as providing teachings known within the prior art. It will be readily appreciated by one of ordinary skill in the art having the benefit of the present disclosure that the system can be used in any number of applications without departing from the spirit or intent of the claimed invention. While a preferred form of the invention has been shown in the drawings and the specifications, since variations in the preferred form will be apparent to those skilled in the art, the invention should not be construed as limited to the specific form shown and described. While the apparatus and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the process and system described herein without departing from the concept and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and concept of the invention. Those skilled in the art will recognize that the method and apparatus of the present invention has many applications, and that the present invention is not limited to the representative examples disclosed herein. Moreover, the scope of the present invention covers conventionally known variations and modifications to the system components described herein, as would be known by those skilled in the art.
While the apparatus and methods of this invention have been described in terms of preferred or illustrative embodiments, it will be apparent to those of skill in the art that variations may be applied to the process described herein without departing from the concept and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and concept of the invention as it is set out in the following claims.

Claims (8)

I Claim:

1. A Multidimensional Gas Chromatography System for analyzing ambient and pressurized fluids comprised of the following :
a. Temperature programmable oven b. External Isothermal oven c. A capillary chromatographic separation column located in the programmable oven to separate lights from heavies, d. A sample inlet external to the programmable oven in fluid communication with a three port stream selection valve.
e. First open end for introducing the sample into the separation pre column, f. A 2nd end for introducing the column effluent to the input of the stream selection valve, g. A transfer line that connects the stream select valve to the inlet of a six port valve contained in the external oven.
h. A six port valve with a large volume loop/trap to contain the "light ends" of the sample, i. A packed separation column contained in the external oven to separate the "light Ends" into its respective components.
j. The outlet of the packed column is in communication with a thermal conductivity detector that is placed in tandem with a flame ionization detector, k. A 2nd capillary analytical column coupled to the stream select valve, l. A stream selection valve that places the pre column in series with the analytical column.
m. A flame ionization detector connected to the outlet of the analytical column.
n. A data system capable of collecting a digital signal from the detectors, displaying the data as a series of peak heights and peak areas, and analyzing the data to perform data integration for the purpose of quantification by peak areas and identification by peak retention times o. A sample injection valve capable of operating leak free from sub ambient pressure to pressures exceeding 20,000 psi at temperatures slightly above ambient p. A low dead volume inline filter, q. A length of high pressure narrow bore tubing to facilitate mixing

2. The gas chromatography system of claim 1 wherein the transfer line connects the injection valve outlet to the inlet of a gas chromatograph or directly to the column inlet in an on column manner

3. The gas chromatography system of claim 1 wherein the sample injection valve further comprises an internal fixed volume.

4. The gas chromatography system of claim 1 wherein the sample injection valve further comprises an external fixed volume sample loop.

5. The gas chromatography system of claim 1 wherein the detectors are selected from the group consisting of: Flame Ionization (FID) or Thermal Conductivity Detector (TCD).

6. A gas chromatography analytical method comprising the steps of:
a. Connect the outlet of the sample vessel (Sample Cylinder, PVT
Cell or Down Hole Tool) to the inlet of the high pressure injection valve using a short (~ 3') length of transfer tubing that is insulated and temperature controlled. In the case of a liquid sample the temperature should be held slightly below the bubble point temperature of the sample fluid. In the case of a gas the temperature should be maintained slightly above the dew point temperature of the sample fluid.
b. Turn the injection valve counter clock wise to the "load" position.
c. Open the metering valve slightly.
d. "Pad" the transfer line between the sample vessel and the Gas Chromatograph with technical grade methane or other suitable fluid at a pressure equal to that of the sample fluid in order to reduce the effect of a liquid flashing, or allowing a gas to retrograde when the sample valve is opened.
e. Close the metering valve to "block in" the system keeping the sample fluid contained in a single phase f. Open the sample valve to allow the fluid to be in communication with the gas Chromatograph.
g. During sample transfer the sample fluid should be maintained at constant temperature and pressure to avoid vaporization or condensation of the sample fluid.
h. Using the sampling system's metering valve slowly purge a small amount of sample (-2 cc) to inventory the sample transfer line and the sampling system's injection valve.
i. Turn the injection valve to clock wise to the "Inject" position thus allowing the valve's internal cavity or external sample loop to be placed in line with the carrier gas j. Simultaneously press the start button on the gas chromatograph to start data collection which simultaneously starts the GC oven temperature program.
k. Close off the sample valve and open the sample metering valve to flash any fluid that remains in the sample transfer line.
l. Allow the Gas Chromatograph to run to completion and process the data in a manner consistent with industry accepted practices of peak area integration and component identification.
m. Detector readings, i.e. peak areas and retention times, are evaluated in combination with sample size to identify components and determine the concentration of components within the sample fluid injected into the GC inlet.

7. An integrated flash apparatus allowing for a single stage flash to atmospheric conditions for the determination of Gas to Oil Ratio (GOR) and fluid shrinkage

8. Provision for inclusion of a "Live Tee" (Dean Switch) downstream of the "Precolumn" and the three way stream select valve and upstream of the "Analytical" column. An auxiliary pressure control to maintain positive pressure on the "Live Tee" (Dean Switch). Auxiliary pressure control is to be programmable so that the pressure at the Live Tee can be adjusted to produce constant flow during oven temperature programming and at a desired point in the analysis the pressure on the Live Tee can be increased to provide forward flow through the "Analytical" Column and reversed flow through the "Precolumn", Injector and out the split vent.