JP2014081233A - Tracer testing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tracer testing method that realizes efficient acquisition of data for accurately identifying parameters relating to advection, dispersion and matrix dispersion in a crack.SOLUTION: A tracer testing method includes: a main testing step S2 for executing multi-tracer testing by injecting a tracer solution, in which a first tracer substance and a second tracer substance are dissolved, into a sample collected from a target bedrock; and a supplementary testing step S4 for executing tracer testing by injecting a tracer solution, in which a third tracer substance different from the first and second tracer substances is dissolved, into the sample at a flow rate different from that in the main testing step S2. The first and third tracer substances are made of non-absorptive tracer substances having mutually equal molecular diffusion coefficients, and the second tracer substance is made of a non-absorptive tracer substance having a molecular diffusion coefficient different from that of the first tracer substance.

Description

  The present invention relates to a tracer test method.

  As a test method to grasp the mass transfer characteristics in rock mass with cracks, tracer solution containing tracer substance is infiltrated from the water injection surface of the rock sample, and the time change of the tracer concentration of the tracer solution flowing out from the discharge surface is measured. There is a tracer test (see, for example, Patent Document 1).

  For example, various parameters related to the movement of pollutants are acquired by conducting a tracer test on the target rocks for radioactive waste geological disposal, and the rocks that make up the natural barrier are analyzed by numerical analysis based on the acquired parameters. An evaluation may be performed.

In the tracer test for rock mass, the crack opening width and the dispersion coefficient in the crack, which are parameters related to advection / dispersion in the crack, which is the main migration path of material, are obtained. However, in rocks with a high porosity such as sedimentary rocks, in addition to these parameters, it is necessary to obtain parameters (matrix diffusion coefficient) related to diffusion from cracks to the rock matrix (matrix).
Here, the advection in the crack means the movement of the substance due to the flow of groundwater, and the dispersion in the crack means the spread of the substance caused by the inhomogeneity of the flow path and flow velocity of the substance in the crack. Refers to the movement of a substance by a concentration gradient. In the tracer test for bedrock, advection and dispersion mainly in the cracks are dominant, but some of the substances moving in the cracks move into the matrix due to diffusion from the cracks to the matrix part. The movement speed of the substance is apparently delayed.

  The three parameters of the crack opening width, the dispersion coefficient in the crack, and the matrix diffusion coefficient are the time-dependent data of the tracer concentration of the tracer solution flowing out from the discharge surface measured by the tracer test (hereinafter referred to as “breakthrough curve”). ) And the solution of the governing equation considering the advection / dispersion and matrix diffusion in the crack. However, it is difficult to determine the three parameters of the crack opening width, the dispersion coefficient in the crack, and the matrix diffusion coefficient at a time from one breakthrough curve data obtained by a single tracer test. Therefore, conventionally, a method of performing a plurality of tracer tests by changing the injection amount of the tracer solution (hereinafter referred to as “multi-flow rate test”), or simultaneously injecting a plurality of tracer solutions having different molecular diffusion coefficients in water. A plurality of breakthrough curve data were obtained by a method (hereinafter referred to as “multitracer test”), and these three parameters were obtained by matching them simultaneously.

  Here, the matching between the breakthrough curve and the solution of the governing equation means that using the solution of the governing equation, the breakthrough obtained from the theoretical curve calculated by sequentially changing the combination of the three parameters and the tracer test. This is to compare the overcurve and find the combination of the three parameters when the breakthrough curve obtained from the tracer test and the theoretical curve are the best match.

JP 2006-64394 A

  However, in order to obtain the above three parameters by a multi-flow rate test or a multi-tracer test, at least one breakthrough curve data among a plurality of obtained breakthrough curve data is obtained from the obtained three parameters. It is necessary to determine the injection flow rate of the tracer solution according to the range by a test performed under appropriately adjusted conditions. If the test is not performed under conditions where the injection flow rate is appropriately adjusted, the three parameters cannot be uniquely determined even if the multi-flow rate test or the multi-tracer test is performed. This is because, among the above three parameters, the sensitivity given to the test result by the difference in crack opening width is particularly low (the shape of the curve of the tracer concentration with time does not change even if the parameter changes).

  Originally, since the above three parameters are unknown parameters, there is a case where an accurate range of the values cannot be estimated in advance. For this reason, all of the plurality of breakthrough curve data acquired by the multi-flow rate test or the multi-tracer test may not be obtained from a test performed under an appropriate flow rate condition. In this case, it was necessary to review the flow conditions and perform the same test again. However, when a retest is carried out, it takes a lot of time and labor to clean the sample and prepare for the test, and therefore development of a more efficient test method has been desired.

  The present invention has been made to solve such problems, and it is effective to use breakthrough curve data for accurately identifying the three parameters of the crack opening width, the dispersion coefficient in the crack, and the matrix diffusion coefficient. It is an object to provide a tracer test method that can be obtained well.

  In order to solve the above-mentioned problem, the invention according to claim 1 performs a multi-tracer test by injecting a tracer solution in which a first tracer substance and a second tracer substance are dissolved into a sample collected from a target rock. And a tracer solution in which a third tracer substance, which is a different tracer substance from the first tracer substance and the second tracer substance, is dissolved in the sample at a flow rate different from that in the main test process. A tracer test method comprising a supplementary test step of performing a tracer test by injecting, wherein the first tracer substance and the third tracer substance have a molecular diffusion coefficient equivalent to each other. The second tracer material has a different molecular diffusion coefficient than the first tracer material. It is characterized by consisting of non-adsorbing tracer substance that.

  According to such a tracer test method, it is possible to efficiently obtain breakthrough curve data capable of accurately identifying parameters by combining the test results of the main test process and the test results of the supplementary test process.

Prior to the main test step, a preparation step for setting the injection flow rate of the tracer solution in the main test step is provided. In the preparation step, among the three parameters, the crack opening width and the matrix diffusion are included. estimating a range of coefficients, the estimated parameters fit to equation 1 to determine the injection flow rate Q _f which α is a dimensionless parameter becomes smaller than the reference value. Here, the dimensionless parameter α represents the ratio of T ₀ and T ₀ ² A ² as shown in Equation 1. Under the condition that α is excessive, the matching of the above three parameters The sensitivity of the crack opening width is reduced, and the above three parameters cannot be determined. Note that T ₀ is an average residence time due to advection in the crack, and A is a migration parameter due to matrix diffusion, which are represented by equations 2 and 3 below.

  The method for estimating the three parameters in the preparation process includes, for example, a method of performing a preliminary test using another sample collected from the vicinity of the sample to be a tracer test, However, the method is not limited to this, and any means may be used.

The invention according to claim 2 is the tracer test method according to claim 1, wherein the injection flow rate of the tracer solution in the supplementary test step is set after the main test step and before the supplementary test step. A flow rate condition setting step for setting, and in the flow rate condition setting step, the result obtained in the multi-tracer test is applied to Equation 1, and an injection flow rate Q _f such that the dimensionless parameter α is below a reference value is set. set, in said supplementary testing process is characterized by carrying out the tracer tests with the infusion rate Q _f more injection flow rate.

  The invention according to claim 3 is the tracer test method according to claim 1 or 2, wherein one of halogen ion iodide ion, bromine ion or chloride ion is used as the first tracer. A tracer substance is used, one of the remaining two is the third tracer substance, and pentafluorobenzoic acid is the second tracer substance. By doing so, it is possible to measure the concentration of the tracer solution even if the tracer test in the supplementary test step is performed without washing the sample after the multitracer test in the main test step.

  According to the tracer test method of the present invention, it is possible to efficiently obtain breakthrough curve data for accurately identifying the three parameters of the crack opening width, the dispersion coefficient in the crack, and the matrix diffusion coefficient.

It is a flowchart which shows the procedure of the tracer test method which concerns on embodiment of this invention. It is a graph which shows an example of the breakthrough curve in which matrix diffusion occurs, and an example of a breakthrough curve in which matrix diffusion does not occur. (A) is a breakthrough curve up to time t = t _0.5 , and (b) is a breakthrough curve in which the injection flow rate of (a) is 1/10. It is a graph which shows the concept of a density change rate. It is a graph which shows the relationship between density change rate and (alpha). (A) is a breakthrough curve based on the multitracer test result of this test process, (b) is a breakthrough curve based on the tracer test of the supplementary test process, and (c) is the first tracer substance in the multitracer test of this test process. FIG. 6 is a breakthrough curve by a third tracer substance in a tracer test of a supplementary test process. It is a schematic diagram which shows the test device of a tracer test.

  As shown in FIG. 1, the tracer test method according to the embodiment of the present invention includes a preparation step S1, a main test step S2, a flow rate condition setting step S3, and a supplementary test step S4. The parameter identification S5 identifies the final values of the three parameters of the crack opening width, the dispersion coefficient in the crack, and the matrix diffusion coefficient from the multitracer test result of the main test process and the tracer test result of the supplementary test process. It is a process.

Preparation process S1 is a process of setting the injection flow rate of the tracer solution from the estimated value of the estimated value and the diffusion coefficient of the rock matrix part (matrix diffusion coefficient) D _m crack opening width 2b in the subject rock. In the setting of infusion rate, and crack opening width, the estimated value of the matrix diffusion coefficient by applying the formula 1, to determine the injection flow rate Q _f which α is smaller than the reference value.

  Here, the method for setting the injection flow rate using Equation 1 described above is for setting the test conditions in consideration of the balance between the advection in the crack and the matrix diffusion among the movement of the tracer solution in the sample under test. Is the method.

FIG. 2 shows an example of a breakthrough curve when matrix diffusion does not occur and when matrix diffusion occurs. For simplicity, FIG. 2 is calculated using Equation 4, which is the theoretical solution of the governing equation (equation with D _f = 0 in Equation 7) ignoring the dispersion in the crack. As shown in FIG. 2, if no dispersion within the crack occurs, and no matrix diffusion occurs, the concentration of the tracer solution discharged through the crack in the sample is that of the tracer solution injected at time t = T ₀ . The concentration increases (c _f / c ₀ = 1.0, where c _f is the concentration of the tracer solution discharged from the sample and c _{0 is} the concentration of the tracer solution injected into the sample). On the other hand, when matrix diffusion occurs, the substance in the crack moves to the matrix part and is stored due to diffusion from the crack to the matrix part while passing through the crack. Is gradually increased from time t = T ₀ onward, and at time t = t _0.5 shown in Formula 5, it rises to ½ of the concentration of the injected tracer solution. Here, T ₀ is an average residence time due to advection in the crack, and T ₀ ² A ² is a delay time due to matrix diffusion, which are expressed as in Expression 15 and Expression 18. Note that t _0.5 in Equation 5 can be obtained by changing c _f / c ₀ in Equation 4 to 0.5 and modifying t. In addition, 1.1 included in Equation 5 is a constant approximately obtained by back calculation of the complementary error function.

FIG. 3 (a) shows a breakthrough curve up to time t = t _0.5 calculated using the equation 4 under the conditions in Table 1. FIG. FIG. 3 also shows changes in the breakthrough curve when only the opening width is changed twice. FIG. 3B shows the result of calculation under the same conditions as in FIG. 3A except that the injection flow rate in FIG. 3A is reduced to 1/10. As shown in FIG. 3, case1 large infusion rate _{Q f,} the change in breakthrough curves for change in the same two times the aperture width is greater than the case2. This difference can be explained as follows in relation to the ratio of the average residence time T ₀ due to advection in the crack and the delay time T ₀ ² A ² due to matrix diffusion. From Expressions 15 and 18, since the injection flow rate Q _f has a relationship of T ₀ ∝1 / Q _f and T ₀ ² A ² ∝1 / Q _f ² , when the injection flow rate Q _f changes, T The ratio of ₀ and T ₀ ² A ² (= α) changes. Since the opening width 2b has a relationship of T ₀ ０2b and is not related to T ₀ ² A ² , the change in the opening width is the time axis direction of the curve corresponding to the change in T ₀ as shown in FIG. Appears as a translation to. In case 2 where the injection flow rate is small, T ₀ is extremely small with respect to the time t _0.5 of interest (that is, T ₀ << T ₀ ² A ² ), so the amount of change in the curve with respect to the change in the opening width is small. It is relatively small. Therefore, under conditions where the injection flow rate is small and the delay time T ₀ ² A ² due to matrix diffusion is excessive with respect to the residence time T ₀ (that is, when α is excessive), It can be said that the sensitivity becomes small and it is difficult to identify a unique parameter.

In order to set a condition in which α is not excessive, the concentration change rate of Equation 6 can be used. FIG. 4 shows the concept of density change rate. The density change rate is a density change rate at time t with respect to a change of γ times the aperture width, and is a value considered as one index of the sensitivity of the aperture width. In Equation 6, c ₁ is a relative concentration (c _f / c ₀ ) in the crack at time t, and c ₂ is a relative concentration (c _f / c ₀ ) at the same time t when the opening width is increased by γ times. is there. As shown in FIG. 4, when paying attention to time t = t _0.5 , substituting Expression 5 into Expressions 11 to 14 can obtain c ₁ and c ₂ of Expression 6, and the density change rate is expressed as α It can be seen that it is expressed by a function of P _e and γ.
Incidentally, Peclet number P _e is a parameter related to the variance of the crack, represented by below formula 16.

FIG. 5 shows the relationship between the density change rate and α with respect to a change in opening width twice (γ = 2.0) when focusing on time t = t _0.5 . FIG. 5 shows three cases of P _e = 1, 10, 100. As shown in FIG. 5, although to varying degrees by the scope of P _e, the concentration change rate is larger as the dimensionless parameter alpha is decreased, alpha becomes more sensitive opening width is can be seen that significantly less. Therefore, based on the relationship of the concentration change rate α in FIG. 5, by providing the reference value of α of Equation 1, it is possible to determine an appropriate infusion rate Q _f. For example, if the density change rate necessary for identifying the aperture width is determined from the measurement accuracy and resolution of the density sensor, and the reference value of α is determined from the relationship between the density change rate and α in FIG. 5 (for example, α < 5), an appropriate injection flow rate _Qf condition can be obtained from Equation 1.

This test process S2 is a process in which a multitracer test is performed by injecting a tracer solution in which two or more kinds of tracer substances are dissolved into the sample 2 collected from the target rock (see FIG. 7).
In the multi-tracer test, a tracer solution in which the first tracer substance and the second tracer substance are dissolved is used.

  The multitracer test of the present embodiment is performed based on the injection flow rate condition determined in the preparation step S1.

  In the present embodiment, iodide ion of halogen ion is used as the first tracer material, but the first tracer material is not limited to iodide ion, for example, bromide ion or chloride of halogen ion. It may be an ion.

The second tracer material comprises a non-adsorbing tracer material having a molecular diffusion coefficient different from that of the first tracer material.
In this embodiment, pentafluorobenzoic acid is used as the second tracer material, but other tracer materials may be used.

When the multi-tracer test is completed, as shown in FIG. 6 (a), two breakthrough curves (breakthrough curve BTC1 obtained from the first tracer substance, obtained from the second tracer substance from the test result) A breakthrough curve BTC2) is created, and the obtained breakthrough curves BTC1 and BTC2 are matched with Equation 11 which is the solution of the governing equations of Equations 7 and 8, and the opening width 2b of the crack in the target rock, the longitudinal direction within the crack The values of the dispersion length α _L and the matrix diffusion coefficient D _m are provisionally determined.

Expressions 7 and 8 are governing equations expressed in consideration of the advection / dispersion phenomenon in the parallel plate crack and the matrix diffusion phenomenon in the direction perpendicular to the crack. Here, the concentration of the tracer solution of c _f the crack, c _m is the coordinate axes of the concentration of the tracer solution in the matrix, x is the coordinate axes of the flow direction of the crack, y is a direction perpendicular to the flow of the crack, t is time, v _f is the flow velocity in the crack, D _f is the dispersion coefficient in the crack, _nm is the porosity of the matrix part, D _m is the matrix diffusion coefficient, and b is 1/2 of the crack opening width (2b: crack (Opening width), α _L is the longitudinal dispersion length in the crack, τ is the bending degree of the rock matrix portion, and D _d is the molecular diffusion coefficient of the solute in free water.

  The governing equations of Equation 7 and Equation 8 can derive the theoretical solution shown in Equation 11 by giving the following initial conditions and boundary conditions.

Here, c ₀ represents the concentration of the tracer solution to be injected, and ξ represents an integral variable.
Y, T, and l are represented by Expression 12, Expression 13, and Expression 14, respectively.

Here, T ₀ is the average residence time in the cracking, P _e is the Peclet number, A is migration parameters by matrix diffusion, respectively formula 15 is expressed by the equation 16 and equation 17.

  Here, L is the length of the crack in the flow direction (tracer transition distance), W is the width of the crack (not the opening width), and is a known parameter determined from the dimensions of the sample.

The delay time T ₀ ² A ² due to matrix diffusion in Equation 5 can be expressed as Equation 18 from Equations 15 and 17.

In matching the tracer test results, first, T ₀ , P _e , and A are obtained by matching the breakthrough curve obtained from the tracer test with the theoretical solution of Expression 11, and the final expression is obtained from the relational expressions of Expressions 15-17. Then, the crack opening width 2b, the dispersion length α _L in the crack, and the matrix diffusion coefficient D _m are obtained. Here, originally also porosity n _m of the matrix portion in the formula 17 is unknown parameter, in this test method, n _m is handled as known parameters.

The matching of the two breakthrough curves (BTC1, BTC2) obtained from the multitracer test is a combination of parameters (T ₀ , P _e , A) that can fit the two breakthrough curves (BTC1, BTC2) simultaneously. And the crack opening width 2b, the dispersion length α _L in the crack, and the matrix diffusion coefficient D _m are calculated from the relational expressions of Expressions 15-17.

In the case of the multitracer test, T ₀ , P _e , and A of two tracer substances having different molecular diffusion coefficients D _d can be expressed by the relationship of Equations 19 to 22 depending on the relationship of the ratio of D _d. it can. Therefore, in the case of the multitracer test, a combination of parameters (T ₀ , P _e , A) that can fit two obtained breakthrough curves at the same time and satisfy the relationship of Expressions 19 to 22 is used. The crack opening width 2b, the dispersion length α _L in the crack, and the matrix diffusion coefficient D _m are calculated from the relational expressions of Expressions 15 to 17.

The flow rate condition setting step S3 verifies the validity of the crack opening width 2b, the rock matrix dispersion length α _L and the matrix diffusion coefficient D _m tentatively determined from the result of the main test step S2, and a supplementary test. It is a step of setting the flow rate condition of the step.

In the flow rate condition setting step S3, the dimension of the dimensionless parameter α is calculated by applying the crack opening width 2b, the dispersion length α _L in the crack, and the matrix diffusion coefficient D _m obtained in the multitracer test to the equation 1, and α is the reference. It is checked whether or not the value exceeds the value, and an injection flow rate Q _f is determined so that α calculated based on Equation 1 does not exceed the reference value.

Here, since the crack opening width 2b, the dispersion length α _L in the crack, and the matrix diffusion coefficient D _m estimated in the preparation step S1 are only estimated values, the crack opening width 2b obtained in the multitracer test, In many cases, the dispersion length α _L does not always match the matrix diffusion coefficient D _m . In the flow rate condition setting step S3, the dimensionless parameter α is calculated by applying the crack opening width 2b, the dispersion length α _L in the crack, and the matrix diffusion coefficient D _m obtained in the multitracer test to Equation 1, and α is prepared. It is checked whether or not the reference value set in step S1 has been exceeded, and the injection flow rate _Qf is determined again so that α does not exceed the reference value.

The supplementary test step S4 is a step of performing a tracer test on the same sample as the sample 2 that has been subjected to the multitracer test in the main test step S2.
The tracer test is performed under the injection flow rate condition determined in the flow rate condition setting step S3.

The third tracer material is composed of a non-adsorbing tracer material different from the first tracer material, but has a molecular diffusion coefficient equivalent to that of the first tracer material.
When iodide ions are used as the first tracer substance, bromine ions or chloride ions are used as the third tracer substance, and chloride ions are used as the first tracer substance. , Iodide ions or bromine ions are used as the third tracer material.

Although the flow rate of the tracer solution in the tracer test is different from the flow rate of the tracer solution in this test process, the first tracer substance and the third tracer substance have the same molecular diffusion coefficient. It can be considered that a plurality of tracer tests (multi-flow rate tests) with different flow rates are being performed.
In this embodiment, the flow rate of the tracer solution in the supplementary test process is larger than the flow rate of the tracer solution in the main test process, but the magnitude of the flow rate in both test processes is not limited.

  When the tracer test is completed, a breakthrough curve (BTC3) is created from the result of the tracer test, as shown in FIG.

The parameter identification S5 is obtained by matching the three breakthrough curves obtained from the result of the test step S2 and the supplementary test step S4 with the theoretical solution of the governing equation (Equation 11). This is a step of finally determining values for each of the longitudinal dispersion length α _L and the matrix diffusion coefficient D _m .

  Note that the tracer test performed in the supplementary test step S4 is performed under a flow rate condition with high sensitivity of the opening width 2b (for example, a condition such that α <5), and therefore the breakthrough curves BTC1, BTC2 and If the three breakthrough curves of BTC3 are matched simultaneously, the three parameters including the opening width 2b can be uniquely determined.

  Of the three breakthrough curves BTC1 to BTC3, BTC1 and BTC2 obtained in this test step S2 are the results of the multitracer test. Can be simultaneously fitted, and parameters satisfying the relations of equations 19 to 22 can be obtained. Further, the BTC3 obtained in the supplementary test step S4 can be treated as a multi-flow rate test performed at different flow rates when combined with the breakthrough curve BTC1 obtained for the first tracer substance in the main test step S2. (See (c) of FIG. 6). Therefore, a combination of parameters that can fit BTC1 and BTC3 at the same time and satisfies the relations of Expressions 23 to 26 may be obtained.

Multi For flow testing, varying only the injection flow rate Q _f tracer solution, since such molecular diffusion coefficient of the tracer substance to the sample or use of interest is the same condition, the injection flow rate Q _f and the varying T ₀ , P _e , A can be expressed as in Expressions 23 to 26 depending on the relationship with the rate of change of the injection flow rate Q _f .

In the parameter identification S5, the three breakthrough curves BTC1 to BTC3 are matched with the theoretical solution (formula 11) of the governing equation, and the three breakthrough curves BTC1 to BTC3 can be fitted simultaneously. ˜22, and combinations of parameters (T ₀ , P _e , A) that satisfy the relational expressions of Expressions 23 to 26 are obtained, and the opening width 2b of the crack in the target rock is calculated from the relational expressions of Expressions 15 to 17 The longitudinal dispersion length α _L and the matrix diffusion coefficient D _m are calculated.

As described above, according to the tracer test method of the present embodiment, since the plurality of breakthrough curves obtained by the multitracer test and the supplemental tracer test performed on the same sample are used, Three mass transfer parameters consisting of the dispersion coefficient in the crack and the matrix diffusion coefficient can be uniquely determined.
In other words, by combining the results of two or more tracer tests performed by changing the flow rate of the tracer solution and the multi-tracer test results of simultaneously injecting two or more kinds of tracer substances, efficient and accurate parameter identification is possible. It becomes possible.

  By using these three mass transfer parameters, it is possible to grasp the movement state of the solute in the target rock, and for example, it can be used when appropriately predicting the movement state of the pollutant.

  Moreover, since the tracer test in the supplementary test process can be performed under appropriate test conditions using the result of the multitracer test in the main test process, a more reliable test result can be obtained.

  Since different tracer substances are used as the tracer substance used in the multi-tracer test in the main test process and the tracer test in the supplementary test process, even if the tracer test is performed without washing the sample after the multi-tracer test, It is possible to measure the concentration of the solution. Therefore, the labor required for cleaning the sample can be omitted.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Boring core 2 Test sample 3 Crack S1 Preparatory process S2 Main test process S3 Flow rate setting process S4 Supplementary test process

Claims (3)

A test process for performing a multi-tracer test by injecting a tracer solution in which a first tracer substance and a second tracer substance are dissolved into a sample collected from a target rock,
A tracer solution in which a third tracer substance, which is a different tracer substance from the first tracer substance and the second tracer substance, is injected into the sample at a flow rate different from the main test step. A tracer test method comprising:
The first tracer material and the third tracer material are composed of non-adsorbing tracer materials having molecular diffusion coefficients equivalent to each other;
The tracer test method, wherein the second tracer substance comprises a non-adsorbing tracer substance having a molecular diffusion coefficient different from that of the first tracer substance. After the main test step and before the supplementary test step, a flow rate condition setting step for setting an injection flow rate of the tracer solution in the supplementary test step is provided,
In the flow rate condition setting step, the result obtained in the multitracer test is applied to Equation 1 to set the injection flow rate Q _f so that the dimensionless parameter α is lower than the reference value,
In the supplementary study process, which comprises carrying out the tracer tests with the infusion rate Q _f more injection flow rate, the tracer test method according to claim 1.

One of the halide ion iodide ion, bromine ion or chloride ion is the first tracer material, and one of the remaining two is the third tracer material,
The tracer test method according to claim 1, wherein pentafluorobenzoic acid is used as the second tracer substance.

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