Automatic tuning of drilling platform gas chromatograms

Abstract

A method for tuning a drilling platform gas chromatography apparatus includes acquiring a chromatogram of a gas sample using a drilling platform GC apparatus at a nominal column temperature and a nominal carrier gas flow rate. The gas sample comprises at least a first light alkane gas and a second light alkane gas (C1 and Cn). And extracting the C1 elution time and the Cn elution time from the obtained chromatogram. And determining an optimal column temperature according to the nominal column temperature, the extracted C1 elution time and the extracted Cn elution time. An optimal carrier gas flow rate is determined as a function of the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, and the extracted C1 elution time. The GC device is then configured to make GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow velocity.

Description

Cross-references to related applications

[0001] none. Background Technology

[0002] During drilling into underground wellbores, circulating drilling fluid typically brings formation fluids and dissolved formation gases to the surface. These gases may be released through the drill bit as it cuts through the formation and can include various alkane gases such as methane (C1), ethane (C2), propane (C3), butane (C4), and pentane (C5), as well as olefins and alcohols. During drilling, the released gas flow is typically assessed at the surface to determine the composition of dissolved gases in the drilling fluid. Such measurements provide valuable information to mud loggers and can offer insights into the maturity and properties of hydrocarbons in the reservoir, the separation and oil quality of the sections being drilled, and information about production areas, lithological variations, reservoir history, or caprock effectiveness.

[0003] Gas chromatography (GC) is frequently used to separate and analyze released gases. In some operations, continuous measurements are taken during drilling to quantify light hydrocarbon compounds (e.g., C1-C5 or C1-C8 alkanes) for a richer and more complete analysis. GC equipment parameterization is typically done manually in the field by adjusting the setpoints of pressure regulators, needle valves, and the GC furnace. These adjustments are necessary to achieve optimal chromatographic resolution for a given equipment, type of chromatographic analysis, gases present in the gas stream, and process conditions. Parameterization and adjustments are time-consuming and require highly skilled GC personnel, who are typically not present on drilling rigs. Furthermore, even when parameterization and adjustments are performed, the resulting parameters and adjustments may be operator-dependent and susceptible to human error.

[0004] The industry needs to improve GC parameterization methods, especially automated methods that can be implemented on drilling platforms. Attached Figure Description

[0005] To gain a more complete understanding of the disclosed subject matter and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings: Figure 1 An example drilling rig including the disclosed gas chromatography equipment is depicted.

[0006] Figure 2 Depicting Figure 1 Another view of a portion of the surface system shown above.

[0007] Figure 3 An example gas chromatography apparatus is described.

[0008] Figure 4 An example column assembly is depicted, in which multiple columns are connected to a multi-port valve.

[0009] Figure 5 Depicting including Figure 4 The block diagram above shows an example GC device with a column assembly.

[0010] Figure 6 Depicting Figure 5 The above shows a schematic diagram of a GC device.

[0011] Figure 7 A flowchart is depicted for an example method for tuning GC devices.

[0012] Figure 8 A flowchart is shown for another example method for tuning GC devices.

[0013] Figure 9 A flowchart is depicted illustrating a method for quality control checks of GC parameters used to perform computations.

[0014] Figure 10A and Figure 10B Example chromatograms obtained with corresponding gas samples are depicted, the gas samples including C1 to C5 alkane gases (10A) and C1 to C8 alkane gases (10B). Detailed Implementation

[0015] This invention discloses a method and system for parameterizing (or tuning) a gas chromatography (GC) apparatus at a drilling platform. An example implementation includes acquiring a chromatogram of a gas sample using a drilling platform GC apparatus at a nominal column temperature and a nominal carrier gas flow rate. The gas sample includes at least a first light alkane gas and a second light alkane gas (C1 and Cn). Elution times for C1 and Cn are extracted from the acquired chromatogram. An optimal column temperature is determined based on the nominal column temperature and the extracted C1 and Cn elution times. An optimal carrier gas flow rate is determined based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, and the extracted C1 elution time. The GC apparatus is then configured to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

[0016] Figure 1An example drilling rig 20 is depicted, including the disclosed GC device 100, which can be configured to automatically perform parameterization at a drilling platform. The drilling rig 20 may be positioned above subsurface formations (not shown). The drilling rig 20 may include, for example, a derrick and lifting equipment (also not shown) for raising and lowering a drill string 30, as shown, which extends into a wellbore 40 and includes, for example, a drill bit 32 and one or more downhole measurement tools 38 (e.g., logging-while-drilling tools or measurement-while-drilling tools) in a bottom hole assembly (BHA) above the drill bit 32. The BHA may also include other tools, such as steering tools (e.g., rotary steering tools) and mud motors. The disclosed embodiments are not limited to any particular BHA configuration.

[0017] The drilling rig 20 also includes a surface system 50 for controlling the flow of drilling fluid used on the rig (e.g., when drilling through the wellbore 40). In the illustrated example rig, drilling fluid 35 can be pumped downhole, for example, via a conventional mud pump 57 (as depicted at 92). Drilling fluid 35 can be pumped, for example, via riser 58 and mud hose 59 en route to drill string 30. Drilling fluid 35 typically emerges from drill string 30 at or near drill bit 32, creating an upwelling flow 94 of mud through the wellbore annulus 42 (the annular space between the drill string and the wellbore wall). In recirculating cases, drilling fluid 35 then flows through return line 52 to mud pool system 56. It should be understood that the terms drilling fluid and mud are used synonymously herein.

[0018] The circulating drilling fluid 35 serves several functions during drilling operations, one of which is to carry drill cuttings 45 to the surface (in the upwelling 94). Drill cuttings 45 are typically removed from the returning mud via a shale vibrating screen 55 (or other similar solids control equipment) in a return pipe (e.g., directly upstream of the mud pit 56).

[0019] Gases released or generated during drilling can also be carried to the surface while circulating drilling fluid 35. As is known to those skilled in the art, formation gases can be released into the wellbore 40 via drilling processes (e.g., by mechanical action of the drill bit to crush formation rock) and can also migrate into the wellbore 40, for example, via fractures in the formation rock. Drilling processes may also generate gases, for example, via drill bit metamorphism (DBM). Once in the wellbore, the gases can be transported to the surface via drilling fluid (in upward-flowing fluid 94). These gases may be dissolved in the mud or present as bubbles and are typically removed from the drilling fluid, for example, via one or more degassers 54 located in or near a shale sluice tank 53, directly upstream of the shale vibrating screen 55 in the example figure. It should be understood that the disclosed embodiments are not limited to gas sampling methods. Drill cuttings 45 and extracted gases are typically examined at the surface to aid drilling operations and to assess the formations and reservoirs traversed by the wellbore.

[0020] Further reference Figure 1 The drilling rig 20 may also include a testing facility 60 (e.g., a mud logging system or laboratory trailer including one or more instruments suitable for various measurements of sampled gases in the drilling fluid). In the depicted embodiment, the testing facility 60 includes a GC instrument 100 configured to measure formation gas composition. Of course, the testing facility 60 may also include numerous other testing instruments known to those skilled in the art.

[0021] Of course, it should be understood that, despite Figure 1 A land-based drilling rig 20 is depicted, but the disclosed embodiments are equally applicable to both land-based and offshore drilling rigs. As is known to those skilled in the art, offshore drilling rigs typically comprise a platform deployed atop a riser extending from the seabed to the water surface. The drill string extends downward from the platform, through the riser, and into the wellbore via a blowout preventer (BOP) located on the seabed. The disclosed embodiments are clearly not limited in these respects.

[0022] Figure 2 Another view depicting a portion of the surface system 50 is shown. As described above, the return conduit 52 is configured to deliver drilling fluid 35 (sometimes including air bubbles 37) from the wellbore 40 to the mud pit 56. For example, the example system 50 includes a degasser 54 deployed, for example, within or near a water collection tank 53 located directly upstream of the shale vibrating screen 55 and the mud pit 56. In this example configuration, the degasser 54 is configured to remove gas from the drilling fluid flowing out of the wellbore 40 (referred to in the industry as gas venting). It should be understood that the disclosed embodiments are not limited in this respect. For example, the degasser 54 may include a first degasser configured to perform gas venting measurements, and a second degasser deployed downstream of the mud pump for performing gas intake measurements.

[0023] It should be understood that the disclosed embodiments are not limited to the use of the depicted degasser. Alternative embodiments may also (or additionally) utilize gas probes located within conduit 52 or at the surface of well 40. In example embodiments, the degasser (or multiple degassers) 54 may be directly connected via piping to a mud logging apparatus or drilling platform laboratory 60 (e.g., as shown at FIG. 65) for example, to automate the delivery of sampled gas for compositional testing.

[0024] It should be understood that system 50 may include virtually any suitable degasser (or degasser unit) 54, such as vacuum degassers, centrifugal degassers, and impeller degassers. Degasser unit 54 may also be configured to heat drilling fluid 35 to promote enhanced degassing of the fluid. The disclosed embodiments are not limited in the type of degasser used. Furthermore, although not depicted, system 50 may include one or more pumps (e.g., suction pumps or pressure booster pumps) configured to pump sampled gas from degasser unit 54 and / or gas probe to laboratory 60. Of course, the disclosed embodiments are not limited in any sampling, pumping, or gas delivery configuration.

[0025] Figure 3 An example GC apparatus 100 is depicted, including a gas sample injection port 142 configured to deliver a gas sample into a column assembly 120, which includes a pre-cut column 124 and a GC main column 126. The GC apparatus 100 also includes a carrier gas supply 175, such as a supply of compressed nitrogen, argon, helium, or air. The injected gas sample may be mixed with the carrier gas and delivered through the column assembly 120. The GC apparatus may also optionally include a trapping column 122 in series with the pre-cut column and configured to remove interfering compounds, such as alcohols, from the gas stream. The pre-cut column 124 may be configured to remove heavy hydrocarbon compounds with a carbon number above a threshold, such as C6, C8, or C10 and above. The main column 126 includes a stationary phase and may be configured to separate various gaseous compounds in the gas sample such that they arrive at detector 160 at different elution times, for example, such that C1 arrives before C2, which arrives before C3, and so on. The detector may include virtually any suitable GC detector, such as a flame ionization detector (FID detector), a TC detector, or a mass spectrometer. Furthermore, while the example GC apparatus 100 includes a trapping column 122 and a pre-cut column 124, it should be understood that the disclosed embodiments are not limited in this respect. The disclosed embodiments are equally well applicable to GC apparatuses that include only a main column or GC apparatuses that include both a main column and a pre-cut column.

[0026] Figure 4 An example column assembly 120 (e.g., including a main column and pre-cut columns) deployed around a mandrel 121 is depicted (the columns are not depicted separately in this figure). These columns are in fluid communication with a multi-port (e.g., 10-port) valve 128. As described in more detail below, the multi-port valve 128 enables gas samples to be guided through the various columns to a detector 160 (…). Figure 2 The depicted column assembly 120 may optionally include one or more heating elements (also not shown) deployed on the mandrel 121. The heating elements enable the temperature of the mandrel and column to be controlled and / or maintained at any temperature, for example, up to about 200°C.

[0027] Figure 5Depicting including Figure 3 The block diagram above shows an example GC device 100 with column assembly 120. As depicted, the column assembly is deployed within a GC housing 102. The device also includes a flow manifold 130 in fluid communication with a multi-port valve 128. The flow manifold 130 may include, for example, multiple controllable valves, pressure regulators, and flow regulators (not shown). In the depicted embodiment, the flow manifold is in fluid communication with the multi-port valve 128 via multiple flow passages at 132, with an external exhaust port at 134, multiple gas inlet ports at 140, and a GC detector 160 at 136. The inlet ports may include, for example, a gas sample injection port 142, a carrier gas injection port 145, and a backflow injection port 148.

[0028] The GC device 100 may also include an electronic controller 150 configured to control the positions of the detector 160, flow manifold 130, injection port, and multi-port valve 128. The controller 150 may be configured to perform the following (see reference below). Figure 7 , Figure 8 and Figure 9 Methods 200, 250, and 300 are described in more detail. It should be understood that the controller may include computer hardware and software configured to cause the GC device to perform the functions described above. The hardware may include one or more processors (e.g., microprocessors) that are connected to one or more data storage devices (e.g., hard disk drives or solid-state drives) and a user interface. It should also be understood that the disclosed embodiments may include processor-executable instructions stored in the data storage device. Of course, the disclosed embodiments are not limited to the use or configuration of any particular computer hardware and / or software.

[0029] Figure 6 Depicting Figure 5 A schematic diagram of the GC device shown above. As depicted, in this example embodiment, the trap column 122, pre-cut column 124, and main column 126 are in fluid communication with a multi-port valve 128. Specifically, the trap column 122 and pre-cut column 124 are connected in series and in fluid communication with ports 1 and 8 of the multi-port valve 128. The main column 126 is in fluid communication with port 7 and detector 160. In this particular embodiment, the carrier gas supply 175 is in fluid communication with ports 6 and 9. In an alternative embodiment, the carrier gas supply may be in fluid communication with port 6, and a separate gas supply (such as backflushing gas) may be in fluid communication with port 9. The gas sample injection port 142 is in fluid communication with port 4. The sample collection loop 170 is in fluid communication with ports 2 and 5. Ports 3 and 10 are exhaust ports. The depicted example GC device 100 also includes multiple pressure regulators 137 and flow regulators 138, as well as an exhaust line 134.

[0030] like Figures 3 to 6As shown, the drilling platform GC analyzer (such as...) Figures 3 to 6 A GC instrument (100) is a complex instrument. In GC measurements, process parameters such as carrier gas flow rate, column temperature, and injection and backflushing times are adjusted to achieve elution of all target components (e.g., C1 to C5 or C1 to C8) within a specified cycle time. Commercial GC instruments used on drilling rigs have standard hardware configurations; however, optimal settings often vary from analyzer to analyzer (even if nominal settings are the same). For example, manufacturing differences, GC column aging, and gas supply quality can all affect optimal settings.

[0031] An example of manufacturing variation is the effective cross-section of a GC column, which can differ between different columns (or between different batches of columns). Nominally identical columns, operating under the same conditions (including the same carrier gas, gas flow rate, and temperature) and having the same column length (and model), often have different elution times for the relevant gases (such as C1 to C5 or C1 to C8) in oilfield GC measurements. Typically, the carrier gas rate must be adjusted to achieve similar elution times.

[0032] Another example of manufacturing variability is inconsistent column coating thickness, a typical characteristic of porous layer-open tube (PLOT) columns. This variability leads to differences in carrier gas rates and inter-column retention times. Furthermore, the quality of the carrier gas supply (especially when air is used) and column aging can significantly affect column retention times and observed elution times. Carrier gas rates and column temperatures are typically adjusted during the analyzer's lifespan. Sometimes, injection and backflushing times also need to be adjusted to achieve specified elution times. As mentioned earlier, these adjustments are very time-consuming and often require highly trained personnel. The industry needs parametric methods (especially automated methods) to obtain chromatograms with pre-specified relevant oilfield gas elution characteristics.

[0033] Turn now Figure 7A flowchart of an example GC parameterization method (a method for tuning a GC device) 200 is depicted. The method includes obtaining a chromatogram of a gas sample at 202 with nominal column temperature and carrier gas flow rate settings. The gas sample may be a calibration sample, for example, comprising various relevant alkane gases. For example, the gas sample may be a calibration sample comprising a standard calibration mixture of C1 to C5 gases (such as C1, C2, C3, iC4, nC4, iC5, and nC5 gases). In another example, the gas sample may be a calibration sample comprising a standard calibration mixture of C1 to C8 gases (such as C1, C2, C3, iC4, nC4, iC5, nC5, nC6, benzene, nC7, toluene, and nC8). Those skilled in the art will understand that in this gas nomenclature, the numbers represent the number of carbon atoms in the alkane gas. In an advantageous embodiment, the gas sample comprises at least C1 and Cn gases, where n is 5, 6, 7, or 8. This can be achieved by setting the carrier gas flow rate (e.g., measured using a mass flow meter) and column temperature to nominal settings and injecting a gas sample into the column assembly (e.g., via...). Figure 3 The chromatogram is obtained by using the injection port 142 in the detector. The detector output can then be plotted over time to provide a chromatogram.

[0034] At position 204, the elution times of C1 and Cn at the nominal GC setting can be extracted from the obtained chromatogram, for example, using peak extraction techniques known to those skilled in the art. and Then, at 206, the optimal column temperature can be calculated based on the extracted C1 and Cn elution times. For example, only the nominal retention factor is considered. It can be calculated based on the following mathematical relationship: For example, the optimal temperature can be calculated using the following mathematical formula. : in Indicates the nominal temperature. It is a known constant, and The retention factor, representing the expected value, can be given as follows: in and This indicates the expected elution time for C1 and Cn gases in the gas sample.

[0035] At point 208, the optimal carrier gas flow rate can be calculated based on the nominal carrier gas flow rate, the calculated optimal temperature, and the nominal temperature. In an example embodiment, the ratio of the optimal carrier gas flow rate to the nominal carrier gas flow rate can be inversely proportional to the ratio of the optimal temperature to the nominal temperature. In an example embodiment, the ratio of the optimal carrier gas flow rate to the nominal carrier gas flow rate can also be inversely proportional to the ratio of the desired C1 elution time to the C1 elution time measured in the chromatogram obtained at point 202. For example, the optimal carrier gas flow rate can be calculated based on the following mathematical relationship. : in These are constants related to the configuration of the GC equipment and can be determined, for example, by empirically obtaining two or more chromatograms at constant temperature and correspondingly different flow rates. In GC equipment commonly used in oilfield applications, .

[0036] Continue to refer to Figure 7 Method 200 may also optionally include calculating the optimal gas sample injection time and backflushing time for GC measurement at 210. In the example implementation, the optimal injection time... It can be calculated, for example, as follows: in This indicates the expected total cycle time or the time between consecutive GC measurements, and This represents the time fraction of the injected gas sample within the precut column and the main column. For a given column configuration, the fraction... It is usually a constant. Backwash time It can be calculated as the difference between the cycle time and the injection time, for example, as shown below: At 212, the GC device can be reconfigured to use the calculated optimal parameter values ​​when performing GC measurements (optimal temperature calculated at 206, optimal carrier gas flow rate calculated at 208, and optional injection and backflushing times calculated at 210).

[0037] Figure 8 A flowchart of another example GC parameterization method 250 is depicted. This method includes obtaining a chromatogram of a gas sample at 252 with nominal column temperature and carrier gas flow rate settings (e.g., as described above in reference method 200 and...). Figure 7 (As described above). The chromatograms obtained can be evaluated at 254 points to automatically calculate the optimal column temperature, optimal carrier gas flow rate, and optimal gas sample injection time, for example, as referenced above. Figure 7The optimal parameters can be set in the GC device at point 256, and further optimization (e.g., quality control checks) can be performed at point 258 to evaluate and optionally adjust the parameters calculated at point 256. Performing quality control checks includes obtaining at least one additional chromatogram (QC chromatogram) and evaluating the chromatogram to determine if further adjustments are needed to any one or more of the optimal carrier gas flow rate, optimal column temperature, and optimal gas sample injection time.

[0038] Figure 9 Describing the use of in Figure 8 The flowchart of an example method 300 is shown at 260 of method 250, where a quality control check of the calculated parameters is performed. At 302, a first QC chromatogram of the gas sample is obtained using the calculated optimal column temperature and carrier gas flow rate settings, which are used in method 200 or 250. Figure 7 and Figure 8 One of the following must be determined. As mentioned above, the gas sample can be a calibration sample, for example, a mixture comprising various relevant alkane gases, such as C1 to C5 or C1 to C8 gases. Then, the quality control method can be as follows: Figure 9 As shown above.

[0039] At 304, the elution time of the C1 peak can be extracted from the first QC chromatogram and compared with a predetermined C1 threshold range to determine whether the C1 elution time is within the tolerance limit of the desired elution time. When the C1 elution time exceeds the predetermined or desired C1 threshold range, the previously calculated optimal carrier gas flow rate can be adjusted at 306. The optimal carrier gas flow rate can be adjusted manually or automatically; for example, when the C1 elution time is less than the threshold range, the carrier gas flow rate can be decreased (adjusted downwards), and when the C1 elution time is greater than the threshold range, the carrier gas flow rate can be increased (adjusted upwards). In an example embodiment, the optimal carrier gas flow rate can be automatically adjusted by a predetermined small value. In other example embodiments, the optimal carrier gas flow rate can be adjusted by an amount proportional to the difference between the measured C1 elution time and the desired C1 elution time, as shown below: in This indicates an adjustment to the optimal carrier gas flow rate. This indicates the difference between the measured C1 elution time and the expected C1 elution time, and This represents the proportionality constant. The method can then be reverted to 302 to obtain another first QC chromatogram.

[0040] When the C1 elution time is within a predetermined range at 304, the elution time of the Cn peak can be extracted from the chromatogram and compared with a predetermined Cn threshold range at 308 to determine whether the Cn elution time is within the tolerance limit of the desired elution time. When the Cn elution time exceeds the predetermined or desired Cn threshold range, the previously calculated optimal column temperature can be adjusted at 310. The optimal column temperature can be adjusted manually or automatically; for example, when the Cn elution time is less than the threshold range, the column temperature can be decreased (adjusted downwards), and when the Cn elution time is greater than the threshold range, the column temperature can be increased (adjusted upwards). In an example embodiment, the optimal column temperature can be automatically adjusted by a predetermined small value. In other example embodiments, the optimal column temperature can be adjusted by an amount proportional to the difference between the measured Cn elution time and the desired Cn elution time, as shown below: in This indicates the adjustment to the optimal column temperature. This indicates the difference between the measured Cn elution time and the expected Cn elution time, and This represents the proportionality constant. The method can then be reverted to 302 to obtain another first QC chromatogram.

[0041] When the Cn elution time is within a predetermined range at 308, a second QC chromatogram can be obtained at 312 using a sample injection time that is greater than the optimal injection time used when obtaining the first QC chromatogram at 302. The first and second peak heights (or amplitudes) of Cn peaks An1 and An2 can be extracted from the corresponding first and second QC chromatograms and compared at 314. When the difference between the Cn amplitude An2 in the second QC chromatogram and the Cn amplitude An1 in the first QC chromatogram exceeds a threshold (i.e., when An2 - An1 is less than the threshold), the sample injection time can be increased at 316. Otherwise, the QC procedure can be completed at 318, and GC parameters can be used in mud logging operations.

[0042] The sample injection time can be adjusted manually or automatically. In the example implementation, the sample injection time can be automatically increased by a predetermined small value. In other example implementations, the sample injection time can be increased by an amount proportional to the difference in Cn peak amplitude, as shown below: in This indicates an adjustment to the sample injection time. This indicates the amplitude difference between Cn peaks, and This represents the proportionality constant. The method can then be reverted to 302 and 312 to obtain another set of first and second QC chromatograms.

[0043] It should be understood that Figures 7 to 9 Methods 200, 250, and 300 can be advantageously performed at the drilling platform (e.g., automatically). Furthermore, GC tuning can be performed at virtually any suitable maintenance interval, or as needed, without requiring highly specialized personnel. For example, GC tuning can be performed at regular QC intervals, such as weekly, monthly, bi-monthly, quarterly, semi-annually, or annually, depending on the nature of the deployment and / or the characteristics of the GC measurement indicator.

[0044] Continue to refer to Figures 7 to 9 It should be understood that the gas sample can include virtually any suitable gas sample, but advantageously includes gas samples (such as calibration samples) of various alkane gases found in downhole oil and gas reservoirs. For example, as described above, the gas sample can be a calibration sample, including a standard calibration mixture of C1, C2, C3, iC4, nC4, iC5, and nC5 gases. In another example, the gas sample can be a calibration sample, including a standard calibration mixture of C1 to C8 gases (it will be readily understood by those skilled in the art that in this nomenclature, the numbers indicate the number of carbon atoms in the alkane gas, e.g., C1 is methane, C2 is ethane, and so on). In an advantageous embodiment, the gas sample includes at least C1 and Cn gases, where n is 5, 6, 7, or 8.

[0045] Figure 10A and Figure 10B Example chromatograms obtained using corresponding gas samples, including C1 to C5 alkane gases (10A) and C1 to C8 alkane gases (10B), are depicted. Figure 10A In the example chromatogram depicted, the peaks of C1, C2, C3, iC4, nC4, iC5, and nC5 are plotted at 402, 404, 406, 408, 410, 412, and 414. Figure 10B In the example chromatogram depicted, the peaks of C1, C2, C3, iC4, nC4, iC5, nC5, nC6, benzene, nC7, toluene, and nC8 are depicted at positions 422, 424, 426, 428, 430, 432, 434, 436, 438, 440, 442, and 444. It should be understood that the depicted chromatogram is merely an example, and the disclosed embodiments are not limited to any particular mixture containing alkane gases or any particular gas sample in any particular gas proportion. Those skilled in the art can readily extract the elution times and peak heights of individual or all gas peaks in the depicted chromatogram.

[0046] It should be understood that this disclosure includes numerous embodiments. These embodiments include, but are not limited to, the following embodiments.

[0047] In a first embodiment, a method for tuning operating parameters in a gas chromatography (GC) apparatus at a drilling platform includes: providing a GC apparatus at the drilling platform, the GC apparatus including at least a pre-cut column, a main column, and a detector in fluid communication with the main column, the main column being configured to separate light alkane gases in a wellbore gas stream; obtaining a chromatogram of a gas sample using the GC apparatus under specified nominal parameter settings, the gas sample including at least a first light alkane gas and a second light alkane gas (C1 and Cn), the specified nominal parameter settings including at least a nominal column temperature and a nominal carrier gas flow rate; extracting C1 elution time and Cn elution time from the obtained chromatogram; calculating an optimal column temperature based on the nominal column temperature and the extracted C1 elution time and Cn elution time; calculating an optimal carrier gas flow rate based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, and the extracted C1 elution time; and configuring the GC apparatus to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

[0048] The second implementation scheme may include the first implementation scheme, wherein the extraction, calculation of the optimal column temperature, calculation of the optimal carrier gas flow rate, and configuration of the GC device are performed automatically.

[0049] The third implementation scheme may include any one of the first to second implementation schemes, wherein calculating the optimal column temperature further includes: calculating a measured retention coefficient based on the extracted C1 elution time and Cn elution time; calculating a desired retention coefficient based on the desired C1 elution time and Cn elution time; and calculating the optimal column temperature based on the nominal column temperature, the measured retention coefficient, and the desired retention coefficient.

[0050] The fourth implementation scheme may include the third implementation scheme, wherein the optimal carrier gas flow rate is calculated based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, the extracted C1 elution time, and the desired C1 elution time.

[0051] The fifth embodiment may include the fourth embodiment, wherein the optimal carrier gas flow rate is calculated using the following mathematical relationship: in This indicates the optimal carrier gas flow rate. This indicates the nominal carrier gas flow rate. This indicates the optimal column temperature. This indicates the nominal column temperature. and This indicates the extracted C1 elution time and the desired C1 elution time. This represents a constant associated with the GC device.

[0052] The sixth embodiment may include any one of the first to fifth embodiments, further comprising: obtaining a second chromatogram of a gas sample using a GC device at a calculated optimal column temperature and a calculated optimal carrier gas flow rate; extracting the C1 elution time from the second chromatogram; comparing the extracted C1 elution time from the second chromatogram with a desired C1 elution time range; and adjusting the optimal carrier gas flow rate downward when the C1 elution time from the second chromatogram is less than the desired C1 elution time range, and adjusting the optimal carrier gas flow rate upward when the C1 elution time from the second chromatogram is greater than the desired C1 elution time range.

[0053] The seventh embodiment may include any one of the first to sixth embodiments, further comprising: obtaining a second chromatogram of a gas sample using a GC device at a calculated optimal column temperature and a calculated optimal carrier gas flow rate; extracting the Cn elution time from the second chromatogram; comparing the extracted Cn elution time from the second chromatogram with a desired Cn elution time range; and adjusting the optimal column temperature downward when the Cn elution time from the second chromatogram is less than the desired Cn elution time range, and adjusting the optimal column temperature upward when the Cn elution time from the second chromatogram is greater than the desired Cn elution time range.

[0054] The eighth embodiment may include any one of the first to seventh embodiments, and further includes: calculating the sample injection time based on the desired measurement cycle time and the pre-cut fraction, the pre-cut fraction being the time fraction of the gas sample in the pre-cut column; and calculating the backwash time as the difference between the desired measurement cycle time and the calculated sample injection time.

[0055] The ninth embodiment may include the eighth embodiment, which further includes: obtaining a second chromatogram of a gas sample using a GC device at a calculated optimal column temperature, a calculated optimal carrier gas flow rate, and a calculated sample injection time; obtaining a third chromatogram of the gas sample using the GC device at a calculated optimal column temperature, a calculated optimal carrier gas flow rate, and an injection time greater than the calculated sample injection time; extracting the amplitude of the Cn peak from the second chromatogram and the third chromatogram; comparing the amplitudes of the Cn peaks from the second chromatogram and the third chromatogram; and adjusting the calculated sample injection time upward when the amplitude of the Cn peak from the second chromatogram is less than the amplitude of the Cn peak from the third chromatogram.

[0056] The tenth embodiment may include any one of the first to ninth embodiments, wherein the light alkane gas includes at least C1 to C5 gas, and Cn is C5.

[0057] The eleventh embodiment may include any one of the first to tenth embodiments, wherein the light alkane gas includes at least C1 to C8 gas, and Cn is C8.

[0058] In a twelfth embodiment, a gas chromatography (GC) apparatus configured for use on a drilling rig and configured to obtain a chromatogram of a gas sample containing at least a first light alkane gas and a second light alkane gas (C1 and Cn) includes: a pre-cut column, a main column, and a GC detector in fluid communication with said main column; and an electronic controller configured to: obtain a chromatogram of the gas sample at a specified nominal column temperature and a specified nominal carrier gas flow rate; extract C1 elution time and Cn elution time from the obtained chromatogram; calculate an optimal column temperature based on the nominal column temperature and the extracted C1 elution time and extracted Cn elution time; calculate an optimal carrier gas flow rate based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, and the extracted C1 elution time; and reconfigure the GC apparatus to perform GC measurements using said calculated optimal column temperature and said calculated optimal carrier gas flow rate.

[0059] The thirteenth embodiment may include the twelfth embodiment, wherein the electronic controller is configured to automatically calculate the optimal column temperature, calculate the optimal carrier gas flow rate, and reconfigure the GC device to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

[0060] The fourteenth embodiment may include any one of the twelfth to thirteenth embodiments, wherein the electronic controller is configured to calculate the optimal carrier gas flow rate using the following mathematical relationship: in This indicates the optimal carrier gas flow rate. This indicates the nominal carrier gas flow rate. This indicates the optimal column temperature. This indicates the nominal column temperature. and This indicates the extracted C1 elution time and the desired C1 elution time. This represents a constant associated with the GC device.

[0061] The fifteenth embodiment may include any one of the twelfth to fourteenth embodiments, wherein the electronic controller is further configured to: calculate a sample injection time based on a desired measurement cycle time and a pre-cut fraction, the pre-cut fraction being the time fraction of the gas sample in the pre-cut column; and calculate a backflushing time as the difference between the desired measurement cycle time and the calculated sample injection time.

[0062] In a sixteenth embodiment, a method for tuning operating parameters in a gas chromatography (GC) apparatus at a drilling platform includes: providing a GC apparatus at the drilling platform, the GC apparatus comprising at least a pre-cut column, a main column, and a detector in fluid communication with the main column, the main column being configured to separate at least a first light alkane gas and a second light alkane gas (C1 and Cn) in a wellbore gas stream; inputting desired C1 elution times and desired Cn elution times into the GC apparatus; causing the GC apparatus to obtain a chromatogram of a gas sample comprising at least a C1 alkane gas and a Cn alkane gas at predetermined nominal parameter settings, the predetermined nominal parameter settings being... The setup includes at least a nominal column temperature and a nominal carrier gas flow rate; automatically extracts C1 elution time and Cn elution time from the obtained chromatogram; automatically calculates an optimal column temperature based on the nominal column temperature, the extracted C1 elution time, the extracted Cn elution time, and the input desired C1 elution time; automatically calculates an optimal carrier gas flow rate based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, the extracted C1 elution time, and the desired C1 elution time; and automatically configures the GC device to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

[0063] The seventeenth embodiment may include the sixteenth embodiment, further comprising: causing the GC apparatus to obtain a second chromatogram of a gas sample using the calculated optimal column temperature and the calculated optimal carrier gas flow rate; automatically extracting the C1 elution time from the second chromatogram; automatically comparing the extracted C1 elution time from the second chromatogram with a desired C1 elution time; and automatically adjusting the optimal carrier gas flow rate when the difference between the extracted C1 elution time from the second chromatogram and the desired C1 elution time exceeds a threshold.

[0064] The eighteenth embodiment may include the seventeenth embodiment, further comprising: extracting Cn elution time from the second chromatogram; comparing the extracted Cn elution time from the second chromatogram with a desired Cn elution time; and adjusting the optimal column temperature when the difference between the Cn elution time from the second chromatogram and the desired Cn elution time exceeds a threshold.

[0065] The nineteenth embodiment may include the eighteenth embodiment, further comprising: calculating a sample injection time based on a desired measurement cycle time and a pre-cut fraction, the pre-cut fraction being the time fraction of the gas sample in the pre-cut column, wherein the second chromatogram is obtained using the calculated sample injection time; causing the GC device to obtain a third chromatogram of the gas sample using the calculated optimal column temperature, the calculated optimal carrier gas flow rate, and an injection time greater than the calculated sample injection time; automatically extracting the amplitude of the Cn peak from each of the second and third chromatograms; comparing the extracted amplitudes of the Cn peak from the second and third chromatograms; and adjusting the calculated sample injection time upward when the amplitude of the Cn peak from the second chromatogram is less than the amplitude of the Cn peak from the third chromatogram.

[0066] The twentieth embodiment may include any one of the sixteenth to nineteenth embodiments, wherein the light alkane gas comprises: at least C1 to C5 gas, and Cn is C5; or at least C1 to C8 gas, and Cn is C8.

[0067] While the automatic tuning of gas chromatograms for drilling platforms has been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.

Claims

1. A method for tuning operating parameters in a gas chromatography (GC) instrument for a drilling platform, the method comprising: A GC device is provided at the drilling platform, the GC device including at least a pre-cut column, a main column and a detector in fluid communication with the main column, the main column being configured to separate light alkane gas from the wellbore gas flow; Under specified nominal parameter settings, the GC device is used to obtain a chromatogram of a gas sample, the gas sample including at least a first light alkane gas and a second light alkane gas (C1 and Cn), and the specified nominal parameter settings include at least a nominal column temperature and a nominal carrier gas flow rate; Extract the elution times of C1 and Cn from the obtained chromatogram; The optimal column temperature is calculated based on the nominal column temperature, the extraction C1 elution time, and the extraction Cn elution time. The optimal carrier gas flow rate is calculated based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, and the extracted C1 elution time; and Configure the GC device to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

2. The method of claim 1, wherein the extraction, the calculation of the optimal column temperature, the calculation of the optimal carrier gas flow rate, and the configuration of the GC device are performed automatically.

3. The method of claim 1, wherein calculating the optimal column temperature further comprises: The retention coefficient was calculated based on the elution time of the extracted C1 and the elution time of the extracted Cn. Calculate the expected retention factor based on the expected C1 elution time and the expected Cn elution time; as well as The optimal column temperature is calculated based on the nominal column temperature, the measured retention factor, and the desired retention factor.

4. The method of claim 3, wherein the optimal carrier gas flow rate is calculated based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, the extracted C1 elution time, and the desired C1 elution time.

5. The method of claim 4, wherein the optimal carrier gas velocity is calculated using the following mathematical formula: wherein represents the optimal carrier gas flow rate, represents the nominal carrier gas flow rate, represents the optimal column temperature, represents the nominal column temperature, and represents the extracted Ci elution time and the expected Ci elution time, and represents a constant related to the GC device.

6. The method of claim 1, further comprising: At the calculated optimal column temperature and the calculated optimal carrier gas flow rate, a second chromatogram of the gas sample was obtained using the GC device; Extract C1 elution time from the second chromatogram; The C1 elution time extracted from the second chromatogram is compared with the desired C1 elution time range; and When the C1 elution time from the second chromatogram is less than the desired C1 elution time range, the optimal carrier gas flow rate is adjusted downwards; and when the C1 elution time from the second chromatogram is greater than the desired C1 elution time range, the optimal carrier gas flow rate is adjusted upwards.

7. The method of claim 1, further comprising: At the calculated optimal column temperature and the calculated optimal carrier gas flow rate, a second chromatogram of the gas sample was obtained using the GC device; Extract Cn from the second chromatogram using the elution time; The elution time of the extracted Cn from the second chromatogram is compared with the expected range of Cn elution times; as well as When the Cn elution time from the second chromatogram is less than the desired Cn elution time range, the optimal column temperature is adjusted downwards; and when the Cn elution time from the second chromatogram is greater than the desired Cn elution time range, the optimal column temperature is adjusted upwards.

8. The method of claim 1, further comprising: The sample injection time is calculated based on the desired measurement cycle time and the pre-cut fraction, where the pre-cut fraction is the time fraction of the gas sample in the pre-cut column; and The backwash time is calculated as the difference between the expected measurement cycle time and the calculated sample injection time.

9. The method of claim 8, further comprising: At the calculated optimal column temperature, the calculated optimal carrier gas flow rate, and the calculated sample injection time, a second chromatogram of the gas sample is obtained using the GC device; A third chromatogram of the gas sample is obtained using the GC device at the calculated optimal column temperature, the calculated optimal carrier gas flow rate, and an injection time greater than the calculated sample injection time. Extract the amplitude of the Cn peak from the second and third chromatograms; Compare the amplitudes of the Cn peaks from the second and third chromatograms; as well as When the amplitude of the Cn peak from the second chromatogram is less than the amplitude of the Cn peak from the third chromatogram, the calculated sample injection time is adjusted upward.

10. The method of claim 1, wherein the light alkane gas comprises at least C1 to C5 gas, and Cn is C5.

11. The method of claim 1, wherein the light alkane gas comprises at least C1 to C8 gas, and Cn is C8.

12. A gas chromatography (GC) apparatus configured for use on a drilling rig and configured to obtain a chromatogram of a gas sample containing at least a light alkane gas, the apparatus comprising: Pre-cut column, main column, and GC detector in fluid communication with the main column; as well as Electronic controller, the electronic controller being configured to: At the specified nominal column temperature and the specified nominal carrier gas flow rate, a chromatogram of the gas sample was obtained; Extract the elution times of C1 and Cn from the obtained chromatogram; The optimal column temperature is calculated based on the nominal column temperature, the extraction C1 elution time, and the extraction Cn elution time. The optimal carrier gas flow rate is calculated based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, and the extracted C1 elution time. as well as The GC device is reconfigured to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

13. The GC device of claim 12, wherein the electronic controller is configured to automatically calculate the optimal column temperature, calculate the optimal carrier gas flow rate, and reconfigure the GC device to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

14. The GC device of claim 12, wherein the electronic controller is configured to calculate the optimal carrier gas flow rate using the following mathematical formula: wherein represents the optimal carrier gas flow rate, represents the nominal carrier gas flow rate, represents the optimal column temperature, represents the nominal column temperature, and represents that the extracted Ci elution time and the expected Ci elution time are known constants, and represents a constant related to the GC device.

15. The GC device of claim 12, wherein the electronic controller is further configured to: The sample injection time is calculated based on the desired measurement cycle time and the pre-cut fraction, where the pre-cut fraction is the time fraction of the gas sample in the pre-cut column; and The backwash time is calculated as the difference between the expected measurement cycle time and the calculated sample injection time.

16. A method for tuning operating parameters in a gas chromatography (GC) apparatus at a drilling platform, the method comprising: A GC device is provided at the drilling platform, the GC device including at least a pre-cut column, a main column and a detector in fluid communication with the main column, the main column being configured to separate light alkane gas from the wellbore gas flow; The desired C1 elution time and the desired Cn elution time are input into the GC device; This causes the GC device to obtain a chromatogram of a gas sample under specified nominal parameter settings, the gas sample including at least C1 alkane gas and Cn alkane gas, the specified nominal parameter settings including at least nominal column temperature and nominal carrier gas flow rate; The C1 elution time and Cn elution time are automatically extracted from the obtained chromatogram; The optimal column temperature is automatically calculated based on the nominal column temperature, the extracted C1 elution time, the extracted Cn elution time, and the input desired C1 elution time and the input desired Cn elution time. The optimal carrier gas flow rate is automatically calculated based on the nominal carrier gas flow rate, the nominal column temperature, the calculated optimal column temperature, the extracted C1 elution time, and the desired C1 elution time; and The GC device is automatically configured to perform GC measurements using the calculated optimal column temperature and the calculated optimal carrier gas flow rate.

17. The method of claim 16, further comprising: This causes the GC device to obtain a second chromatogram of the gas sample using the calculated optimal column temperature and the calculated optimal carrier gas flow rate; The C1 elution time is automatically extracted from the second chromatogram; The extracted C1 elution time from the second chromatogram is automatically compared with the desired C1 elution time; as well as When the difference between the extracted C1 elution time from the second chromatogram and the desired C1 elution time exceeds a threshold, the optimal carrier gas flow rate is automatically adjusted.

18. The method of claim 17, further comprising: Extract Cn from the second chromatogram using the elution time; The extraction Cn elution time from the second chromatogram is compared with the expected Cn elution time; as well as When the difference between the Cn elution time from the second chromatogram and the desired Cn elution time exceeds a threshold, the optimal column temperature is adjusted.

19. The method of claim 18, further comprising: The sample injection time is calculated based on the desired measurement cycle time and the pre-cut fraction, where the pre-cut fraction is the time fraction of the gas sample in the pre-cut column, and the second chromatogram is obtained using the calculated sample injection time; This causes the GC device to obtain a third chromatogram of the gas sample using the calculated optimal column temperature, the calculated optimal carrier gas flow rate, and an injection time greater than the calculated sample injection time; The amplitude of the Cn peak is automatically extracted from each of the second and third chromatograms; Compare the amplitude of the extracted Cn peak from the second chromatogram and the third chromatogram; as well as When the amplitude of the Cn peak from the second chromatogram is less than the amplitude of the Cn peak from the third chromatogram, the calculated sample injection time is adjusted upward.

20. The method of claim 16, wherein the light alkane gas comprises: At least C1 to C5 gases, and Cn is C5; or At least C1 to C8 gases, and Cn is C8.

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