A quantitative calculation method for reservoir throat length based on constant-rate mercury intrusion porosimetry experiments

Abstract

This invention provides a quantitative calculation method for reservoir throat length based on constant-rate mercury intrusion porosimetry (CRMP) experiments, belonging to the field of oil and gas field development data information processing technology. The method includes: calculating the endpoint values ​​of the mercury intrusion intervals of each throat level based on CRMP experimental data; determining the mercury intrusion saturation of each throat level based on the endpoint values ​​of the interval radius and the mercury intrusion curve data determined by CRMP experiments; obtaining the mercury intrusion volume of each interval based on the calculated mercury intrusion saturation and the pore volume of the rock sample; calculating the mercury intrusion volume of a single throat interval using the interval mercury intrusion volume and the number of throats; and finally, quantitatively calculating the length of each throat level based on the throat radius. This invention provides a quantitative calculation method for throat length, offering a new technical approach for determining reservoir throat length and providing strong data support for research on reservoir throat length and its variation patterns, reservoir throat geometry, and reservoir throat network simulation.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development data information processing technology, and in particular to a method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion testing. Background Technology

[0002] As the core carrier for the storage and migration of oil, gas, and other mineral resources, reservoirs are fundamentally determined by the geometry of their internal pore-throat system, which directly impacts their permeability, storage capacity, and resource extraction efficiency. This makes them a core research focus in oil and gas geological exploration and development. Throats, as narrow channels connecting the pores within the reservoir, have openings and extensions that are key geometric parameters characterizing their permeability. These parameters directly control the flow path and migration efficiency of fluids within the reservoir, playing an irreplaceable role in reservoir evaluation, production prediction, and development scheme optimization. Among the core characteristic parameters of throats, the throat radius and throat length together constitute the basic indicators describing their geometry. Their synergistic effect determines the permeability resistance and fluid conduction efficiency of the throat. However, due to the small size (typically in the micrometer to nanometer range), dispersed spatial distribution, and tortuous three-dimensional morphology of reservoir throats, accurate characterization of their geometric parameters has always been a technical challenge in reservoir geology.

[0003] Currently, the testing and analysis methods for throat parameters mainly focus on one-dimensional mercury intrusion porosimetry (such as conventional mercury intrusion porosimetry and constant-rate mercury intrusion porosimetry) and two-dimensional electron microscopy (SEM) image observation (such as SEM and TEM). However, existing technologies still have significant limitations in the quantitative characterization of throat length: one-dimensional mercury intrusion porosimetry mainly reflects the connectivity and radius distribution of the throat through pressure-saturation curves, and its experimental principle is difficult to directly relate to the spatial extension distance of the throat, making it impossible to directly or indirectly deduce the throat length from experimental data; two-dimensional electron microscopy image observation can only obtain the projection shape of the throat on a two-dimensional plane, and cannot fully restore its three-dimensional meandering characteristics. Moreover, due to the limitations of the observation field and the randomness of sample preparation, it is difficult to achieve systematic and statistical quantitative analysis of throat lengths of different orders. The lack of quantitative data on throat length not only restricts people's comprehensive and in-depth understanding of the geometry of reservoir throats, but also directly affects the accurate construction of reservoir throat network models. Existing throat network simulations often employ simplified length assumptions (such as equal-length throats and empirical assignments), leading to significant deviations between simulation results and the actual seepage characteristics of reservoirs. This, in turn, affects the reliability of reservoir seepage mechanism analysis, production capacity prediction, and development scheme optimization. Summary of the Invention

[0004] The purpose of this invention is to provide a quantitative calculation method for reservoir throat length based on constant-rate mercury intrusion porosimetry (CRMP). By using information on the number of throats of different grades determined by CRMP and data on mercury ingress pressure curves in the throats, an innovative analytical calculation method for reservoir throat length based on CRMP is constructed. This solves the technical problem of unclear understanding of reservoir throat length caused by the difficulty in accurately measuring throat length in existing technologies, and enables quantitative calculation of reservoir throat length, providing strong support for reservoir research and oil and gas field development.

[0005] To achieve the above objectives, this invention proposes a method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry experiments, comprising the following steps:

[0006] Step S1: Based on the information on the radius and number of throats of different grades determined by the constant rate mercury intrusion test, calculate the endpoint value of the interval radius of the mercury intrusion interval in which each throat is located;

[0007] Step S2: Calculate the mercury inlet pressure endpoint values ​​for each throat based on the interval radius endpoint values ​​for each throat level;

[0008] Step S3: Based on the endpoint values ​​of the mercury inlet pressure in each throat level, and combined with the mercury inlet pressure curve data of the throat level determined by the constant rate mercury inlet pressure experiment, calculate the endpoint values ​​of the mercury inlet saturation in each throat level, and determine the mercury inlet saturation in each throat level.

[0009] Step S4: Calculate the mercury ingress volume of each throat based on the mercury saturation of each throat and the pore volume of the rock sample;

[0010] Step S5: Calculate the mercury ingress volume of a single throat at each level based on the information on the interval mercury ingress volume and the number of throats at each level.

[0011] Step S6: Calculate the length of each throat based on the mercury inlet volume and throat radius of each single throat.

[0012] Preferably, in step S1, the endpoint values ​​of the mercury inlet pressure for each stage of the throat are calculated using the following formula:

[0013] ;

[0014] ;

[0015] ;

[0016] in, For the first The lower limit of the radius of the mercury inlet interval where the primary throat is located. For the first The upper limit of the radius of the mercury inlet zone where the primary throat is located. For the first The radius of the larynx. For the first The radius of the larynx. For the first The radius of the larynx. The step length between each level of the throat. This is the count of valid larynx levels with a number of larynxes greater than zero.

[0017] Preferably, in step S2, the calculation formula is as follows, based on the interval radius endpoint values ​​of the throats at each level:

[0018] ;

[0019] ;

[0020] in, For the first The lower limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located. For the first The upper limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located. The surface tension of mercury, The angle for mercury wetting.

[0021] Preferably, step S3 includes the following steps:

[0022] Step S31: Based on the interval mercury inlet pressure endpoint values ​​of each throat level, search for the test interval on the throat mercury pressure curve where the interval mercury inlet pressure endpoint values ​​of each throat level lie in the mercury inlet pressure data column. Using the throat mercury inlet pressure and mercury saturation at two test points within this test interval, calculate the interval mercury inlet saturation endpoint values ​​of each throat level. The calculation formula is as follows:

[0023] ;

[0024] ;

[0025] in, For the first The lower limit of mercury saturation in the mercury inlet zone where the primary throat is located. For the first The upper limit of mercury saturation in the mercury inlet zone where the primary throat is located. The first value of the mercury inlet pressure endpoint on the throat mercury pressure curve that includes the interval of mercury inlet pressure values The first test interval Mercury inlet pressure at each test point The first value of the mercury inlet pressure endpoint on the throat mercury pressure curve that includes the interval of mercury inlet pressure values The first test interval Mercury inlet pressure at each test point On the laryngeal mercury intrusion curve The corresponding mercury saturation, On the laryngeal mercury intrusion curve The corresponding mercury saturation, This represents the total number of points in the laryngeal mercury porosimetry test.

[0026] Step S32: Based on the endpoint values ​​of the mercury saturation of each throat level, calculate the mercury saturation of each throat level using the following formula:

[0027] ;

[0028] in, For the first Mercury saturation in the mercury inlet zone where the throat is located.

[0029] Preferably, in step S4, the mercury ingress volume of each throat is calculated based on the mercury saturation of each throat and the pore volume of the rock sample. The calculation formula is as follows:

[0030] ;

[0031] in, For the first The mercury ingress volume within the mercury ingress zone where the primary throat is located. This represents the pore volume of the rock sample.

[0032] Preferably, in step S5, the mercury ingress volume of each individual throat is calculated using the following formula:

[0033] ;

[0034] in, For the first The volume of mercury entering the space within a single throat. For the first The number of larynxes.

[0035] Preferably, in step S6, based on the mercury inlet volume and throat radius of each individual throat, the individual throat is set as a curved circular tube of equal diameter, and a capillary model is used to calculate the length of each throat. The calculation formula is as follows:

[0036] ;

[0037] in, For the first Grade 1 throat length.

[0038] Therefore, this invention proposes a quantitative calculation method for reservoir throat length based on constant-rate mercury intrusion porosimetry experiments, the advantages of which are as follows:

[0039] (1) This invention constructs an analytical calculation method for reservoir throat length based on constant rate mercury intrusion test, which realizes the quantitative calculation of reservoir throat length for the first time, fills the gap in the existing technology in this field, and solves the technical problem that traditional experimental methods are difficult to accurately measure throat length.

[0040] (2) This invention makes full use of the existing throat radius, number and mercury intrusion curve data of constant rate mercury intrusion test, without adding extra experimental costs. The method is simple, easy to implement and highly operable, and is applicable to the calculation of throat length of various reservoir rock samples.

[0041] (3) The calculation results of this invention can accurately reflect the length distribution law of each level of throat (such as the power function relationship between throat radius and length), providing key data support for reservoir throat geometry research, throat network simulation, oil and gas seepage mechanism analysis and oil and gas field development scheme optimization, and has broad application prospects. Attached Figure Description

[0042] Figure 1 A schematic diagram of reservoir pores and throats;

[0043] Figure 2 A flowchart of a method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry experiments;

[0044] Figure 3 A histogram of throat tract distribution;

[0045] Figure 4 This is a mercury pressure curve of the larynx;

[0046] Figure 5 A schematic diagram of a throat capillary model;

[0047] Figure 6 This is a schematic diagram showing the relationship between the radius and length of the larynx. Detailed Implementation

[0048] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0049] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0050] Example 1

[0051] Throats are narrow channels connecting pores, with relatively small openings, controlling the reservoir's ability to filter fluids. Reservoir pores and throats, like... Figure 1 As shown. The area of ​​a certain oil field is known to be 5000 km². 2The main producing layer of the oilfield is the Chang 8 oil group of the Yanchang Formation in the Triassic system, which belongs to the delta front sedimentary deposits. The average porosity of the reservoir is 12.1%, and the average permeability is 1.19 x 10. -3 μm 2 This is a low-porosity, low-permeability reservoir. Taking the No. 10 rock sample (2056.0m) from Well Xi 105 in the Chang 8 oil group of this oilfield as an example, the constant-rate mercury intrusion porosimetry experimental data of this rock sample are shown in Table 1:

[0052] Table 1. Data from constant-rate mercury intrusion porosimetry experiments on rock samples

[0053]

[0054] Table 1 reflects the basic information of rock sample #10 and the results of throat detection, including a mercury saturation of 23.58% in the throat, a number of 5605 throats, and an average throat radius of 0.98µm.

[0055] like Figure 2 As shown, this invention proposes a method for quantitatively calculating the reservoir throat length based on constant-rate mercury intrusion porosimetry experiments, comprising the following steps:

[0056] Step S1: Based on the information on the radius and number of throats at different levels determined by the constant-rate mercury intrusion porosimetry experiment, calculate the endpoint values ​​of the interval radius of the mercury intrusion interval in which each level of throat is located. The results of constant-rate mercury intrusion porosimetry throat detection and the calculation results of throat parameters at each level are shown in Table 2.

[0057] Table 2. Results of constant-rate mercury injection laryngeal tract testing and calculation results of laryngeal parameters at each level.

[0058] (Continued)

[0059]

[0060] (Continued)

[0061]

[0062] (Continued)

[0063]

[0064] Based on the data in Table 2, a histogram of the distribution of throats in the rock samples was drawn, as shown below. Figure 3 As shown in the figure, the throat radius of the rock sample is distributed in the range of 0.1~1.5µm, showing a coarse skewed distribution. The peak number of throats appears at 1.3µm, with a total of 597 throats and an average throat radius of 0.98µm.

[0065] Table 2 shows the radius and number of throats of different grades. A total of 101 grades of throats with radii between 0 and 10 μm were detected using the constant-rate mercury porosimetry experiment. The throat radius step size was... Among them, the effective laryngeal tract order count with a number of larynxes greater than zero is: Based on the test results, the endpoint values ​​of the mercury inlet pressure for each level of the throat were calculated using the following formula:

[0066] ;

[0067] ;

[0068] ;

[0069] in, For the first The lower limit of the radius of the mercury inlet zone where the primary throat is located, in micrometers (μm). For the first The upper limit of the radius of the mercury inlet zone where the primary throat is located, in micrometers (μm). For the first The radius of the throat, measured in micrometers (μm). For the first The radius of the throat, measured in micrometers (μm). For the first The radius of the throat, measured in micrometers (μm). This refers to the step size between different levels of the throat, typically 0.1 μm. This is the count of valid larynx levels with a number of larynxes greater than zero.

[0070] Step S2: Based on the interval radius endpoint values ​​of each throat level, calculate the interval mercury inlet pressure endpoint values ​​of each throat level, specifically as follows:

[0071] Based on the interval radius endpoint values ​​of each throat level in Table 2, calculate the mercury inlet pressure endpoint values ​​of each throat level using the following formula:

[0072] ;

[0073] ;

[0074] in, For the first The lower limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located, in megapascals (MPa). For the first The upper limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located, in megapascals (MPa). The surface tension of mercury is 0.48 N / m. For the mercury-wetting angle, or .

[0075] The calculation results are shown in Table 2. The upper limit of the mercury inlet pressure in the interval is no greater than the maximum mercury inlet pressure of 6.2 MPa.

[0076] Step S3: Based on the endpoint values ​​of the mercury inlet pressure in each throat level, and combined with the mercury inlet pressure curve data of the throat level determined by the constant rate mercury inlet pressure experiment, calculate the endpoint values ​​of the mercury inlet saturation in each throat level, and determine the mercury inlet saturation in each throat level.

[0077] The constant-rate mercury intrusion porosimetry (MRP) throat pulse data are shown in Table 3, with a total of 277 test points. Based on the constant-rate mercury intrusion porosimetry throat pulse data in Table 3, the throat pulse data for this rock sample was plotted. Figure 4 As shown in the figure, the mercury saturation in the throat of the rock sample increases continuously with the increase of the mercury ingress pressure at the test point, forming a monotonically increasing curve. When the mercury ingress pressure reaches 6.2 MPa, the maximum mercury saturation of the rock sample is 23.58%.

[0078] Table 3. Data on constant-rate mercury intrusion porosimetry curves in the throat.

[0079]

[0080] (Continued)

[0081]

[0082] (Continued)

[0083]

[0084] (Continued)

[0085]

[0086] (Continued)

[0087]

[0088] (Continued)

[0089]

[0090] (Continued)

[0091]

[0092] (Continued)

[0093]

[0094] Step S31: Based on the interval mercury inlet pressure endpoint values ​​for each throat level in Table 2, search for the test interval on the throat mercury pressure curve where the interval mercury inlet pressure endpoint value for each throat level falls. Using the throat mercury inlet pressure and mercury saturation at two test points within this test interval, calculate the interval mercury inlet saturation endpoint value for each throat level. The calculation formula is as follows:

[0095] ;

[0096] ;

[0097] in, For the first The lower limit of mercury saturation in the mercury inlet zone where the primary throat is located. For the first The upper limit of mercury saturation in the mercury inlet zone where the primary throat is located. The first value of the mercury inlet pressure endpoint on the throat mercury pressure curve that includes the interval of mercury inlet pressure values The first test interval The mercury inlet pressure at each test point is expressed in megapascals (MPa). The first value of the mercury inlet pressure endpoint on the throat mercury pressure curve that includes the interval of mercury inlet pressure values The first test interval The mercury inlet pressure at each test point is expressed in megapascals (MPa). On the laryngeal mercury intrusion curve The corresponding mercury saturation, On the laryngeal mercury intrusion curve The corresponding mercury saturation, This represents the total number of points in the laryngeal mercury porosimetry test. ;

[0098] Step S32: Based on the endpoint values ​​of the mercury saturation of each throat level, calculate the mercury saturation of each throat level using the following formula:

[0099] ;

[0100] in, For the first The mercury saturation of the mercury inlet zone within the primary throat is shown in columns 8-10 of Table 8.

[0101] Step S4: Based on the mercury ingress saturation and rock sample pore volume of each throat level in Table 2, calculate the mercury ingress volume of each throat level. The calculation formula is as follows:

[0102] ;

[0103] in, For the first The mercury inlet volume of the mercury inlet interval where the primary throat is located, in mm. 3 , The volume of the rock sample pores is expressed in cm³. 3 The results are shown in Table 2.

[0104] Step S5: Based on the mercury ingress volume and number of throats at each level in Table 2, calculate the mercury ingress volume of a single throat at each level. The calculation formula is as follows:

[0105] ;

[0106] in, For the first The volume of mercury entering a single throat section, in cubic millimeters (mm). 3 , For the first The number of grade 1 larynxes, in units of individual larynxes, is calculated as shown in Table 2.

[0107] Step S6: Based on the mercury inlet volume and throat radius of each single throat level in Table 2, use the following method... Figure 5 The capillary model shown is used to calculate the length of each stage of the throat using the following formula:

[0108] ;

[0109] in, For the first The length of the throat, in meters, is calculated as shown in Table 2.

[0110] Based on the larynx radius and larynx length in Table 2, a graph showing the relationship between the larynx radius and larynx length was drawn, as follows: Figure 6 As shown in the figure, the smaller the reservoir throat radius, the larger the throat length, and the two exhibit a close power-law correlation, with the multiple correlation coefficient R0... 2 =0.9895.

[0111] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0112] Therefore, this invention addresses the problem of unclear understanding of reservoir throat length caused by the inability to accurately measure throat length using traditional one-dimensional mercury intrusion porosimetry (MIP) or two-dimensional electron microscopy (TEM) imaging methods. Utilizing information on the number of throats of different orders determined by constant-rate mercury intrusion porosimetry (CRMP) and data on mercury ingress pressure curves in the throats, this invention constructs an analytical calculation method for reservoir throat length based on CRMP. This method achieves quantitative calculation of reservoir throat length and reveals the variation law of reservoir throat length. This invention fills the gap in quantitative calculation methods for throat length, provides a new technical approach for determining reservoir throat length, and is simple, easy to implement, and highly operable. The calculation results can provide strong data support for research on reservoir throat length and its variation law, reservoir throat geometry, and reservoir throat network simulation, with broad application prospects.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry, characterized in that, Includes the following steps: Step S1: Based on the information on the radius and number of throats of different grades determined by the constant rate mercury intrusion test, calculate the endpoint value of the interval radius of the mercury intrusion interval in which each throat is located; Step S2: Calculate the mercury inlet pressure endpoint values ​​for each throat based on the interval radius endpoint values ​​for each throat level; Step S3: Based on the endpoint values ​​of the mercury inlet pressure in each throat level, and combined with the mercury inlet pressure curve data of the throat level determined by the constant rate mercury inlet pressure experiment, calculate the endpoint values ​​of the mercury inlet saturation in each throat level, and determine the mercury inlet saturation in each throat level. Step S4: Calculate the mercury ingress volume of each throat based on the mercury saturation of each throat and the pore volume of the rock sample; Step S5: Calculate the mercury ingress volume of a single throat at each level based on the information on the interval mercury ingress volume and the number of throats at each level. Step S6: Calculate the length of each throat based on the mercury inlet volume and throat radius of each single throat.

2. The method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry as described in claim 1, characterized in that: In step S1, the endpoint values ​​of the mercury inlet pressure for each stage of the throat are calculated using the following formula: ； ； ； in, For the first The lower limit of the radius of the mercury inlet interval where the primary throat is located. For the first The upper limit of the radius of the mercury inlet zone where the primary throat is located. For the first The radius of the larynx. For the first The radius of the larynx. For the first The radius of the larynx. The step length between each level of the throat. This is the count of valid larynx levels with a number of larynxes greater than zero.

3. The method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry according to claim 1, characterized in that: In step S2, the calculation formula is as follows, based on the interval radius endpoint values ​​of the throats at each level: ； ； in, For the first The lower limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located. For the first The upper limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located. The surface tension of mercury, For the mercury-wetting angle, For the first The lower limit of the radius of the mercury inlet interval where the primary throat is located. For the first The upper limit of the radius of the mercury inlet zone where the primary throat is located. This is the count of valid larynx levels with a number of larynxes greater than zero.

4. The method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry according to claim 1, characterized in that: Step S3 includes the following steps: Step S31: Based on the interval mercury inlet pressure endpoint values ​​of each throat level, search for the test interval on the throat mercury pressure curve where the interval mercury inlet pressure endpoint values ​​of each throat level lie in the mercury inlet pressure data column. Using the throat mercury inlet pressure and mercury saturation at two test points within this test interval, calculate the interval mercury inlet saturation endpoint values ​​of each throat level. The calculation formula is as follows: ； ； in, For the first The lower limit of mercury saturation in the mercury inlet zone where the primary throat is located. For the first The upper limit of mercury saturation in the mercury inlet zone where the primary throat is located. The first value of the mercury inlet pressure endpoint on the throat mercury pressure curve that includes the interval of mercury inlet pressure values The first test interval Mercury inlet pressure at each test point The first value of the mercury inlet pressure endpoint on the throat mercury pressure curve that includes the interval of mercury inlet pressure values The first test interval Mercury inlet pressure at each test point On the laryngeal mercury intrusion curve The corresponding mercury saturation, On the laryngeal mercury intrusion curve The corresponding mercury saturation, This represents the total number of points in the laryngeal mercury porosimetry test. For the first The lower limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located. For the first The upper limit of the mercury inlet pressure in the mercury inlet zone where the primary throat is located. Count the effective laryngeal levels when the number of laryngeal passages is greater than zero; Step S32: Based on the endpoint values ​​of the mercury saturation of each throat level, calculate the mercury saturation of each throat level using the following formula: ； in, For the first Mercury saturation in the mercury inlet zone where the primary throat is located. This is the count of valid larynx levels with a number of larynxes greater than zero.

5. The method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry according to claim 1, characterized in that: In step S4, the mercury ingress volume of each throat is calculated based on the mercury saturation of each throat and the pore volume of the rock sample. The calculation formula is as follows: ； in, For the first The mercury ingress volume within the mercury ingress zone where the primary throat is located. The pore volume of the rock sample. For the first Mercury saturation in the mercury inlet zone where the primary throat is located. This is the count of valid larynx levels with a number of larynxes greater than zero.

6. The method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry according to claim 1, characterized in that: In step S5, the mercury ingress volume of each individual throat is calculated using the following formula: ； in, For the first The volume of mercury entering the space within a single throat. For the first The mercury ingress volume within the mercury ingress zone where the primary throat is located. For the first The number of larynxes This is the count of valid larynx levels with a number of larynxes greater than zero.

7. The method for quantitatively calculating reservoir throat length based on constant-rate mercury intrusion porosimetry according to claim 1, characterized in that: In step S6, based on the mercury inlet volume and throat radius of each individual throat, the individual throat is set as a curved circular tube of equal diameter. Using a capillary model, the length of each throat is calculated using the following formula: ； in, For the first Grade 1 throat length, For the first The volume of mercury entering the space within a single throat. For the first The radius of the larynx. This is the count of valid larynx levels with a number of larynxes greater than zero.

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