Storage type isotope water absorption profile tracking logging and interpretation method

Abstract

The invention provides a storage type isotope water absorption profile tracking well logging and interpretation method. The well logging method comprises the steps that 11, isotope water absorption profile well logging related information is prepared; 12, calculating simulated migration time when the isotope reaches different underground positions; and 13, determining proper logging time for logging by referring to the simulated migration time. The well logging and interpretation method comprises the following steps: step 21, recording a well logging curve of an isotope in an underground migration process; step 22, judging and explaining the water absorption capacity of each layer; step 23, carrying out inversion calculation on the isotope simulation migration time by utilizing the water absorption capacity of each layer explained in the step 22; and step 24, verifying an interpretation result by using the isotope simulation migration time inversely calculated in the step 23. According to the storage type isotope water absorption profile tracking logging and interpretation method, the problem of blind measurement of steel wire storage logging is effectively solved, the influences of isotope contamination and stratum large pore channels can be effectively reduced, and the interpretation data quality is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield development, and particularly to a storage-type isotope water absorption profile tracing logging and interpretation method. Background Art

[0002] Radioactive isotope water absorption profile logging is a major logging project for dynamic monitoring. After the isotope tracer is released, it is necessary to wait for the tracer to fully accumulate in each perforation layer along with the flow of the injected water before measuring the isotope curve. If the isotope curve is measured too early, the tracer has not reached the formation; or if the waiting time is too long and the isotope curve logging is measured too late, a part of the small-particle-size tracer will enter the deep formation and the isotope display amplitude will become smaller. Both of these situations affect the accuracy of the isotope logging data. Especially for the storage-type water absorption profile logging, due to "blind logging", a more reasonable isotope logging time setting is required. The conventional isotope water absorption profile data interpretation method calculates the water absorption volume of each layer by the amount of isotope tracer accumulated in the formation, but the size of the formation pore channels and isotope contamination have a great impact on the accuracy of the data.

[0003] In the Chinese patent application with the application number: CN99113053.7, it relates to an isotope water absorption profile logging method, which can measure the highest peak value of the curve when the isotope just enters the high water absorption layer. By using a simple calculation method, the water absorption profile can be accurately calculated. The influence caused by the large pore channels that prevent the downhole tool from measuring the high-amplitude isotope layer or contamination is eliminated. The accuracy and precision of the isotope water absorption profile logging curve are improved. Its construction process is simple and easy to operate, and it is especially suitable for on-site popularization and application. However, this method is only suitable for direct-reading logging; it is difficult to capture the moment when the isotope amplitude changes the most in each layer when there are multiple layers.

[0004] In the "Method for Reducing Contamination in Isotope Water Absorption Profile Logging" (Proceedings of the 2014 International Conference on Reservoir Monitoring and Management (2014ICRSM), 2014-07), through the analysis of a large amount of actual data, the main three types of contamination in isotope water absorption profile logging are obtained, namely, the isotope is not evenly mixed, the specific gravity is too large resulting in sinking contamination, and tool and collar contamination. Methods for reducing contamination by changing the isotope release position, changing the specific gravity of isotope particles, and putting cold balls are tried. The test results show that the accuracy of the data can be effectively improved. However, this method is effective in reducing contamination, but it cannot solve the "blind logging" time setting problem of storage logging and cannot solve the influence of large pore channels.

[0005] In "Research on Tracer Injection Profile Logging Technology" (Proceedings of the 2021 International Conference on Oil and Gas Field Exploration and Development (Volume II), October 20, 2021), the traditional isotope water absorption profile uses the isotope area superposition method to obtain the relative water absorption of each layer, which can reflect the water absorption rhythm of the water absorption layer and judge the phenomena such as channeling and leakage outside the pipe. The advantages are combined with the advantages of the liquid tracer water absorption profile test, which calculates the flow rate by continuously monitoring the depth and time of the liquid isotope migrating in the well, can effectively avoid the influence of contamination and retention on the peak reading, and the obtained fluid velocity is more accurate, thus forming the tracer injection profile logging technology. However, for this technology, two processes need to be tested in one well, and the test cost is high; liquid tracer logging is difficult for large flow rate and multi-layer testing, not easy to promote, and has low adaptability; there is great environmental protection pressure in the application of liquid isotopes.

[0006] All of the above existing technologies are quite different from the present invention and cannot solve the technical problems we want to solve. Therefore, we have invented a new method for storing isotope water absorption profile tracing logging and interpretation. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for radioactive isotope water absorption profile logging applicable to oilfield injection wells, which has good application and promotion prospects and significant economic and social benefits.

[0008] The purpose of the present invention can be achieved by the following technical measures: The method for storing isotope water absorption profile tracing logging includes:

[0009] Step 11: Prepare the relevant data for isotope water absorption profile logging;

[0010] Step 12: Calculate the simulated migration time for the isotope to reach different positions downhole;

[0011] Step 13: Determine the appropriate logging time for logging with reference to the simulated migration time.

[0012] The purpose of the present invention can also be achieved by the following technical measures:

[0013] In step 11, the relevant data for isotope water absorption profile logging includes: logging task book, injection string structure and dimensions, perforated interval, injection volume, injection pressure, type and salinity of injected water ions.

[0014] In step 12, the simulated migration time is the time for the tracer to migrate from the release point to different positions downhole. Different positions downhole generally use the depth of downhole tools and the upper and lower boundaries of the water injection layer.

[0015] In step 12, the method of segmenting is used to calculate the simulated migration time, including: the calculation method for the simulated migration time of general injection wells and the calculation method for the simulated migration time of separate injection wells.

[0016] In step 12, the calculation formula for the simulated migration time of the general water injection well is as follows:

[0017]

[0018] T1 i = T2 i -th i 1 << i << n

[0019] T1 i : The time for the isotope to migrate to the first interface of the i-th layer;

[0020] T2 i : The time for the isotope to migrate to the second interface of the i-th layer;

[0021] t0: The migration time of the isotope from the release point to the bell mouth;

[0022] tl1: The migration time between the bell mouth and the first layer;

[0023] th1: The migration time of the isotope within the first perforated layer;

[0024] tl i : The migration time between the (i - 1)-th layer and the i-th layer of the isotope, i ≥ 2;

[0025] th i : The migration time of the isotope within the i-th perforated layer, 1 ≤ i ≤ n;

[0026] n: The total number of layers within the section.

[0027] In step 12, the calculation formula for the simulated migration time of the separate water injection well is as follows:

[0028]

[0029] T1 i = T2 i -th i 1 << i << n

[0030] T1 i : The time for the isotope to migrate to the first interface of the i-th layer of the k-th water distributor;

[0031] T2 i : The time for the isotope to migrate to the second interface of the i-th layer of the k-th water distributor;

[0032] th i : The migration time of the isotope within the i-th perforated layer of the k-th water distributor;

[0033] tl i:Migration time between the (i-1)-th layer and the i-th layer of the k-th water distributor for isotopes, where i≥2;

[0034] tl1: Migration time from the k-th water distributor to the corresponding 1st layer;

[0035] tt1: Time for the isotope to migrate from the release point Y to the first water distributor;

[0036] tt i : Migration time from the (j-1)-th water distributor to the j-th water distributor section, where j≥2;

[0037] n: Total number of layers within a section;

[0038] m: Number of water distributors.

[0039] In step 12, different water absorption models are used to calculate the simulated migration time, so as to change the water injection volume of each layer of the injection well, and calculate the time for the isotope to reach each layer under various conditions, providing a theoretical basis for setting the time of the memory-type isotope water absorption profile logging.

[0040] In step 12, a few typical models are adopted for different water absorption models. The typical models mainly include: (1) Average model: The water absorption volume of each layer is the same; (2) Uniform flow model: The water injection intensity of each layer is the same; (3) Single-layer water absorption ratio longest time model: Calculate the longest tracer arrival time of each layer when the water absorption volume of each layer is a certain ratio; (4) Determine the most likely water absorption ratio model according to the previous year's logging data and formation characteristics, and thus obtain the probable time range for the isotope of the injection well to reach each layer, providing a theoretical basis for setting the time of the memory-type isotope water absorption profile logging.

[0041] In step 13, determine the appropriate logging time for logging with reference to the simulated migration time calculated in step 12, and record the logging curve during the downhole migration process of the isotope.

[0042] The object of the present invention can also be achieved by the following technical measures: A memory-type isotope water absorption profile tracing logging and interpretation method, which includes:

[0043] Step 21, record the logging curve during the downhole migration process of the isotope;

[0044] Step 22, judge and interpret the water absorption volume of each layer;

[0045] Step 23, inversely calculate the simulated migration time of the isotope by using the water absorption volume of each layer interpreted in step 22;

[0046] Step 24, verify the interpretation result by using the simulated migration time of the isotope inversely calculated in step 23.

[0047] The object of the present invention can also be achieved by the following technical measures:

[0048] In step 21, during the downhole isotope migration process, record the curves of isotope migration at multiple different time periods and the curves of the isotope being relatively stationary at each layer.

[0049] In step 22, based on the isotope migration curves and the conventional filtration product method of the isotope water absorption profile, preliminarily judge and interpret the water absorption volume of each layer.

[0050] In step 23, using the interpretation result of step 22, adopt the simulated migration time calculation method in step 12 of claim 1 to inversely calculate the simulated migration time for the isotope tracer to reach different positions downhole.

[0051] In step 24, by comparing the actual migration time for the isotope tracer to reach different positions downhole in the tracing logging with the simulated migration time calculated in step 23, verify whether the interpretation result conforms to the actual migration time law of the isotope. If it conforms, it indicates that the interpretation result conforms to the actual situation. If it does not conform, in combination with other situations, adjust the parameters as appropriate to correct the influence of the formation pore size and isotope contamination on the data until the actual dynamic migration time and the simulated migration time are basically the same.

[0052] Compared with the prior art, the present invention has the following technical advantages:

[0053] 1. Effectively solve the "blind measurement" problem of wireline storage logging.

[0054] The calculation of the simulated migration time of the isotope water absorption profile changes the on-site construction of storage logging from relying on experience in the past to relying on technology, improves the logging success rate, and ensures the quality of logging data.

[0055] 2. The quality of the interpreted data is improved.

[0056] The comprehensive interpretation method combining isotope static and dynamic data corrects the water absorption volume of each layer calculated by the conventional isotope filtration product method, reduces the influence of the formation pore size and isotope contamination on the data, and can greatly improve the accuracy of the interpretation of the water absorption profile data, belonging to the advanced level in the country. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of a general water injection string with the bell mouth below the water injection layer in a specific embodiment of the present invention;

[0058] Figure 2 It is a schematic diagram of a stratified water injection string in a specific embodiment of the present invention;

[0059] Figure 3 It is a schematic diagram of a well string in a specific embodiment of the present invention;

[0060] Figure 4 Pipe string diagram of a certain well in a specific embodiment of the present invention;

[0061] Figure 5 Tracing log curve diagram of a certain well in a specific embodiment of the present invention;

[0062] Figure 6 Isotope water absorption profile interpretation result diagram of a certain well in a specific embodiment of the present invention.

[0063] Figure 7 Flow chart of a specific embodiment of the stored isotope water absorption profile tracing logging method of the present invention;

[0064] Figure 8 Flow chart of a specific embodiment of the stored isotope water absorption profile tracing logging and interpretation method of the present invention;

[0065] In the figure, 1 is the casing, 2 is the tubing, 3 is the flared opening, 4 is the packer, 5 is the water distributor, Y is the tracer release point, Z1, Z2, Z n Perforated layers, namely the 1#, 2#, and 7# perforated layers. Detailed implementation manners

[0066] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0067] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0068] Figure 7 Flow chart of a specific embodiment of the stored isotope water absorption profile tracing logging method of the present invention. The stored isotope water absorption profile tracing logging method of the present invention includes:

[0069] Step 11: Prepare relevant data for isotope water absorption profile logging;

[0070] Step 12: Calculate the simulated migration time for the isotope to reach different positions downhole;

[0071] Step 13: Determine the appropriate logging time for logging with reference to the simulated migration time.

[0072] In step 11, the relevant data of isotope water absorption profile logging includes the logging task sheet, the structure and size of the injection string, the perforated interval, the injection volume, the injection pressure, the type and salinity of the injected water ions, etc.

[0073] In step 12, the simulated migration time is the time for the tracer to migrate from the release point to different positions in the wellbore. Different positions in the wellbore generally use the depth of downhole tools and the upper and lower boundaries of the injection layers.

[0074] In step 13, determine the appropriate logging time for logging based on the simulated migration time calculated in step 12, and record the logging curve during the migration process of the isotope in the wellbore.

[0075] The time for the isotope tracer to reach different positions in the wellbore from the release depth depends on the release depth of the isotope tracer, the total injection volume, the structure of the downhole string, and the water absorption ratio of each layer. The release depth of the isotope tracer, the injection string in the wellbore, and the total injection volume are determined before logging. Therefore, for a specific well, the time for the tracer to reach each formation only relates to the water absorption volume of each layer. When the water absorption volume of each layer changes, the time for the tracer to reach each layer also changes accordingly. Different water absorption conditions correspond to different tracer arrival times, thus forming a range of simulated migration times for the tracer to reach each layer. Based on the simulated migration time and the range of simulated migration times, it provides a basis for setting the tracking logging time and reduces the unreasonable situation of setting the storage-type water absorption profile logging time.

[0076] 1. Calculation method for simulated migration time of general injection wells

[0077] For example Figure 1 , take the general injection string with the flared mouth below the injection layer as an example.

[0078] Let the actual total injection volume of the whole well be Q, and the static sedimentation velocity of the isotope be v f [[ID=!22]]There are n perforated intervals Z1, Z2, …… Zn n , the water absorption volume of each layer is q1, q2 …… qn n , the inner diameter of the tubing is d ti , the outer diameter is d te , the inner diameter of the casing is d ci , the thickness of each layer is h1, h2, …… hn n , the distance between each layer is L1, L2 …… Ln n , L1 is the distance from layer Z1 to the flared mouth, and the isotope release position is Y, and the distance from Y to the flared mouth is L0.

[0079] Inner diameter area of the tubing:

[0080] Annular area between tubing and casing:

[0081] (1) Calculation of interlayer flow velocity

[0082] Z i and Z i+1 Interlayer flow velocity v i+1 =(Q - (q1 + q2 + … + q i-1 )) / S j -v f

[0083] 1 ≤ i ≤ n - 1;

[0084] The flow velocity v1 between Z1 and the bell mouth = Q / S j -v f ;

[0085] (2) Calculation of intra - layer flow velocity

[0086] Assume that the water absorption within each layer is uniform. Then the average migration velocity of the isotope within the layer is the average of the velocities at the lower and upper bounds of the layer. That is:

[0087] Z n Average intra - layer flow velocity vz n = v n / 2;

[0088] Z i Average intra - layer flow velocity vz i =(v i + v i+1 ) / 2 1 ≤ i ≤ n - 1;

[0089] (3) Calculation of flow velocity in the tubing

[0090] V t = Q / S t + v f ;

[0091] (4) Calculation of migration time of isotope reaching different positions

[0092] Knowing the migration velocity and length of each section, the time for the isotope to migrate to different positions can be calculated by accumulation.

[0093] th1 = L1 / vz1;

[0094] tl1 = L1 / v1

[0095] ……

[0096] th i = h i / vz i 1 ≤ i ≤ n;

[0097] tl i = L i / v i1 ≤ i ≤ n:

[0098] ……

[0099] t0 = L0 / V t ;

[0100] Then:

[0101]

[0102] T1 i = T2 i -th i 1 << i << n

[0103] T1 i : The time for the isotope to migrate to the first interface of the i-th layer;

[0104] T2 i : The time for the isotope to migrate to the second interface of the i-th layer;

[0105] t0: The migration time of the isotope from the release point to the bell mouth;

[0106] tl1: The migration time between the bell mouth and the first layer;

[0107] th1: The migration time of the isotope within the first perforated layer;

[0108] tl i : The migration time between the (i - 1)-th layer and the i-th layer of the isotope, i ≥ 2;

[0109] th i : The migration time of the isotope within the i-th perforated layer; 1 ≤ i ≤ n

[0110] n: The total number of layers.

[0111] (5) For the case where the water injection layer is below the bell mouth or there are water injection layers both above and below the bell mouth, the calculation method in (1)-(4) can also be used to calculate the simulated migration time of the isotope at different positions in each segment.

[0112] 2. Calculation method for the simulated migration time of a separate water injection well

[0113] Such as Figure 2 , a separate water injection string with m water distributors, which are P1, P2,...P k ...P m , and the upper and lower segments of each layer corresponding to the water distributor are calculated separately. Let there be n water injection layers corresponding above the k-th water distributor.

[0114] (1) Calculation of the isotope migration time in the tubing

[0115] The isotope is released at position Y. Different from general water injection, the migration time of the isotope in the tubing string is considered. Let the water injection volumes of each water distributor be Q1, Q2, … Q k … Q m , the distance between the isotope release position Y and the first water distributor is Lp1, the distance between the first water distributor and the second water distributor is Lp2, and so on. The distance between the (k - 1)th and the kth water distributors is Lp k , and the still - water sedimentation velocity of the isotope is v f , then:

[0116] The velocity of the isotope migrating from the release point Y to the first water distributor: vt1 = Q / S t + v f

[0117] The time for the isotope to migrate from the release point Y to the first water distributor: tt1 = Lp1 / vt1

[0118] The migration velocity from the first water distributor to the second water distributor: vt2=(Q - Q1) / S t + v f

[0119] The migration time from the first water distributor to the second water distributor: tt2 = Lp2 / vt2

[0120] And so on:

[0121] The migration velocity from the (k - 1)th water distributor to the kth water distributor:

[0122] vt k =(Q - Q1 - … Q k-1 ) / S t + v f

[0123] The migration time from the (k - 1)th water distributor to the kth water distributor:

[0124] tt k = Lp k / vt k

[0125] (2) Calculation of the isotope migration time in the annulus section

[0126] The calculation method is the same as that of general water injection 1. Change the total well water injection volume Q to the total water injection volume Q of each layer in the calculated section k , then the migration time of the isotope at different positions in each section can be calculated using the sectional method in 1.

[0127] (3) Calculation formula for the migration time of the isotope reaching different positions

[0128]

[0129] T1 i = T2 i -th i 1 << i << n

[0130] T1 i : The time when the isotope migrates to the first interface of the i-th layer above the k-th water distributor;

[0131] T2 i : The time when the isotope migrates to the second interface of the i-th layer above the k-th water distributor;

[0132] th i : The migration time of the isotope in the i-th perforated layer above the k-th water distributor;

[0133] tl i : The migration time of the isotope between the (i - 1)-th layer and the i-th layer above the k-th water distributor, i ≥ 2;

[0134] tl1: The migration time between the k-th water distributor and the first layer above it;

[0135] tt1: The time when the isotope migrates from the release point Y to the first water distributor;

[0136] tt j : The migration time from the (j - 1)-th water distributor to the j-th water distributor section, j ≥ 2;

[0137] n: The total number of layers in the section;

[0138] m: The number of water distributors.

[0139] Similarly, the isotope migration time at different positions within the section below the i-th water distributor can be calculated. Thus, the isotope migration time corresponding to any water distributor at any different position in the water injection well with separate injection can be calculated.

[0140] In step 12, different water absorption models are used in the simulation of the migration time calculation to change the water injection volume of each layer in the water injection well, and the time when the isotope reaches each layer is calculated under various conditions. This provides a theoretical basis for setting the time of the memory-type isotope water absorption profile logging.

[0141] In step 12, a few typical models are adopted for different water absorption models. The typical models mainly include: (1) Average model: The water absorption volume of each layer is the same; (2) Uniform flow model: The water injection intensity of each layer is the same; (3) Single-layer water absorption ratio longest time model: The longest tracer arrival time of each layer is calculated when the water absorption volume of each layer can be 40%, 20%, and 10% respectively; (4) The most likely water absorption ratio model is determined according to the previous logging data and formation characteristics.

[0142] By using different models to change the water injection volume of each layer of the water injection well and calculating the time for the isotope to reach each layer under various conditions using the aforementioned simulated migration time calculation method, the probable time range for the isotope in the water injection well to reach different positions downhole can be obtained, providing a theoretical basis for setting the time for the memory isotope water absorption profile logging.

[0143] In step 13, determine the appropriate logging time for logging with reference to the simulated migration time calculated in step 12, and record the logging curves during the downhole migration of the isotope.

[0144] As Figure 8 shown, Figure 8 is a flow chart of a specific embodiment of the memory isotope water absorption profile tracing logging and interpretation method of the present invention. The memory isotope water absorption profile tracing logging and interpretation method includes:

[0145] Step 21, record the logging curves during the downhole migration of the isotope.

[0146] Step 22, judge and interpret the water absorption volume of each layer.

[0147] Step 23, inversely calculate the simulated migration time of the isotope by using the water absorption volume of each layer interpreted in step 22.

[0148] Step 24, verify the interpretation result by using the simulated migration time of the isotope inversely calculated in step 23.

[0149] In step 21, during the downhole migration of the isotope, record multiple curves during the isotope migration at different time periods and the curves when the isotope reaches relative rest at each layer. The tracing logging can refer to the previous Figure 7 .

[0150] In step 22, preliminarily judge and interpret the water absorption volume of each layer according to the isotope migration curve and the conventional filtering product method of the isotope water absorption profile.

[0151] Step 23, inversely calculate the simulated migration time of the isotope tracer reaching different positions downhole by using the interpretation result of step 22 and the simulated migration time calculation method in step 12 of claim 1.

[0152] For the simulation calculation method at different depth positions other than the upper and lower bounds of the layer, the position depth for calculating the simulated migration time can be set to the upper or lower bound of the non-water-absorbing layer to calculate the time, and the simulated migration time calculation method in step 12 can also be used.

[0153] Step 24: By comparing the actual time when the isotope tracer in the tracing logging reaches different positions downhole with the simulated migration time calculated in Step 23, verify whether the interpretation result conforms to the actual migration time law of the isotope. If it conforms, it indicates that the interpretation result conforms to the actual situation. If not, considering other circumstances, adjust the parameters as appropriate to correct the influence of factors such as formation pore size and isotope contamination on the data until the actual dynamic migration time is basically consistent with the simulated migration time.

[0154] The following are several specific embodiments of applying the present invention

[0155] Embodiment 1

[0156] In a specific implementation manner 1 of applying the present invention, a method for calculating the simulated migration time of a general water injection well.

[0157] For example Figure 3 :

[0158] There are n1 water injection intervals above the bell mouth and n2 water injection intervals below the bell mouth. The total number of water injection layers is:

[0159] N = n1 + n2

[0160] Then, using Figure 7 the calculation formula for the simulated migration time of the general water injection well in

[0161]

[0162] T1 i = T2 i -th i 1 << i << n1

[0163] T1 i : The time when the isotope migrates to the first interface of the i-th layer above the bell mouth;

[0164] T2 i : The time when the isotope migrates to the second interface of the i-th layer above the bell mouth;

[0165] t0: The migration time of the isotope release point to the bell mouth;

[0166] tl1: The migration time between the bell mouth and the first layer above the bell mouth;

[0167] tl i : The migration time of the isotope between the (i - 1)-th layer and the i-th layer above the bell mouth, i ≥ 2;

[0168] th i : The migration time of the isotope within the i-th perforated layer above the bell mouth; 1 ≤ i ≤ n1

[0169] n1: Figure 3 Total number of layers above the bellmouth

[0170] The simulated migration time of the section below the bellmouth is calculated as:

[0171]

[0172] T1 i = T2 i -th i 1 << i << n2

[0173] T1 i : Migration time of the isotope to the first interface of the i-th layer below the bellmouth;

[0174] T2 i : Migration time of the isotope to the second interface of the i-th layer below the bellmouth;

[0175] t0: Migration time of the isotope release point to the bellmouth;

[0176] tl1: Migration time between the bellmouth and the first layer below the bellmouth;

[0177] tl i : Migration time of the isotope between the (i - 1)-th layer and the i-th layer below the bellmouth, i ≥ 2;

[0178] th i : Migration time of the isotope within the i-th perforated layer below the bellmouth; 1 ≤ i ≤ n2

[0179] n2: Figure 3 Total number of layers below the bellmouth

[0180] Thus, the simulated migration time of all water injection layers of this well can be calculated.

[0181] Example 2

[0182] In a specific implementation manner 1 of applying the present invention, the memory isotope water absorption profile tracing logging and interpretation method includes:

[0183] In step 12, a few typical models are adopted for different water absorption models. The typical models mainly include: (1) Average model: The water absorption amount of each layer is the same; (2) Uniform flow model: The water injection intensity of each layer is the same; (3) Single-layer water absorption ratio longest time model: Calculate the longest tracer arrival time of each layer when the water absorption amount of each layer can be 40%, 20%, and 10% respectively; (4) Determine the most likely water absorption ratio model according to previous logging data and formation characteristics.

[0184] By using different models to change the water injection volume of each layer in the water injection well and calculating the time for the isotope to reach each layer under various conditions using the aforementioned simulated migration time calculation method, the probable time range for the isotope in the water injection well to reach different positions downhole can be obtained, providing a theoretical basis for setting the time for the memory isotope water absorption profile logging.

[0185] For the isotope water absorption profile logging, the water absorption volume of each layer can be calculated by the area method only after the isotope tracer has fully filtered and deposited on the formation after reaching each formation. Therefore, knowing the time for the tracer to reach each formation is of great guiding significance for the memory logging operation. The time for the isotope tracer to reach different positions downhole from the release depth depends on the release depth of the isotope tracer, the total water injection volume, the downhole string structure, and the water absorption ratio of each layer. Since the release depth of the isotope tracer, the downhole water injection string, and the total water injection volume are determined before the logging, for a specific well, the time for the tracer to reach each formation is only related to the water absorption volume of each layer. When the water absorption volume of each layer changes, the time for the tracer to reach each layer also changes accordingly. Different water absorption conditions correspond to different tracer arrival times, thus forming a time range for the tracer to reach each layer.

[0186] Isotope logging should not only capture the layers with fast water absorption. Especially for large pore channels, if the logging waiting time is too long, a large part of the isotope may enter the formation. It is also necessary to measure the layers with small water absorption. Four main models are selected to calculate the tracer arrival time to comprehensively understand the tracer time range, so as to provide a basis for determining a reasonable tracking logging time and improve the logging quality and success rate.

[0187] 1. Average model: When the water absorption volume of each layer is the same, i.e.:

[0188] q i =Q / N

[0189] q i —— Water injection volume per single layer, unit: m³ / day.

[0190] N—— Total number of layers;

[0191] Q—— Actual water injection volume, unit: m³ / day;

[0192] 2. Uniform flow model: When the injection intensity of each layer is the same and the water absorption ratio is calculated according to the length of the interval, the water absorption volume of each layer is:

[0193] q i =Q·l i / l t

[0194] l i —— Length of the i-th perforation interval;

[0195] l t —— Total length of the perforation intervals.

[0196] Average model and uniform flow model: Provide the most likely time range. Since water injection wells mostly absorb water in several layers in most cases, it reflects the general situation and provides the logging time under normal circumstances.

[0197] 3. Single-layer water absorption ratio longest time model: Calculate the longest tracer arrival time for each layer according to the water absorption amount of each layer being 40%, 20%, and 10% respectively.

[0198] The single-layer water absorption ratio longest time model reflects extreme cases and provides a reference for the longest logging waiting time.

[0199] For example Figure 1 :

[0200] Z n The longest migration time for the water absorption amount of layer Z accounting for 40% of the whole well is from Z2 to Z n-1 When neither absorbs water and the water absorption of layer Z1 accounts for 60% of the whole well, which is an extreme case. By analogy, such extreme cases can also be found for other layers.

[0201] 4. Determine the most likely water absorption ratio model based on previous logging data and formation characteristics.

[0202] Embodiment 3

[0203] In a specific Embodiment 3 of applying the present invention, the memory isotope water absorption profile tracing logging method for wells includes the following steps:

[0204] Step 11, Prepare relevant data for isotope water absorption profile logging;

[0205] Step 12, Calculate the simulated migration time for the isotope to reach different positions downhole;

[0206] Step 13, Determine the appropriate logging time for logging with reference to the simulated migration time.

[0207] Example: The well string diagram of XXX can be seen in Figure 4 , Casing 5 1 / 2, tubing 2 7 / 8, bell mouth depth 3177 meters, surface water meter injection 60 cubic meters per day. The data of each perforated layer is shown in Table 1:

[0208] The calculated migration time of the typical model is shown in Table 2. The previous logging data of this well shows that each layer absorbs water, and the time for the isotope to reach each layer in the average and uniform flow models is less than 60 minutes. The appropriate tracing logging time determined using the simulated migration time is:

[0209] Release isotopes at 3070 meters. After a 5-minute interval, measure the first isotope tracing curve. Trace the isotopes in the tubing, calculate and correct the actual water injection volume of the whole well, and the logging takes 14 minutes. After a 40-minute interval, measure the second isotope curve, mainly tracing the migration of isotopes between layers, and the logging takes 14 minutes. After a 10-minute interval, measure the third isotope curve, mainly showing the static curve of isotope filtration after injection into the water injection layer. See the logging curves in Figure 4 . The first isotope curve 1 traced the migration of the isotope curve in the tubing, the second isotope curve 2 traced the migration of the isotope between layers, and the third isotope curve 3 showed that the isotopes had basically reached each water injection layer. The appropriate tracing logging time was determined by using the simulated migration time method.

[0210] Table 1 Data Sheet of Perforated Interval of Well XXX

[0211]

[0212] Table 2 Calculation Data Sheet of Migration Time of Typical Model of Well XXX

[0213]

[0214]

[0215] Example 4

[0216] In a specific Example 4 of applying the present invention, the memory isotope water absorption profile tracing logging and interpretation method includes:

[0217] Step 21, record the logging curves during the downhole migration process of the isotopes.

[0218] Step 22, judge and interpret the water absorption volume of each layer.

[0219] Step 23, inversely calculate the simulated migration time of the isotopes by using the water absorption volume of each layer interpreted in Step 22.

[0220] Step 24, verify the interpretation results by using the simulated migration time of the isotopes inversely calculated in Step 23.

[0221] Based on the tracing logging curves in Example 3, judge and interpret the water absorption volume of each layer according to the isotope migration curve and the conventional filtration method of the isotope water absorption profile. There is isotope contamination in this well, and isotope contamination correction is carried out. The water absorption of each layer is calculated by using the conventional isotope filtration method as shown in Table 3:

[0222] There are 3 isotope tracing curves in this well, such as Figure 5 , and there are a total of two isotope migration fronts. According to the isotope simulated migration time calculation method, the data in Table 3 are inversely calculated for the isotope simulated migration time and compared with the actual logging isotope front time, as shown in Table 4:

[0223] Table 4 shows that the simulated migration time of the isotope front of the isotope curve 1 in the tubing is smaller than the actual logging time, indicating that the total well injection volume shown by the surface water meter is on the high side. Since the isotope migration in the tubing is only related to the total well injection volume in the tubing, the total well water volume Q is calculated to be 53 cubic meters per day using the isotope migration distance and time in the tubing. The total well injection volume is corrected, and then the simulated migration time is inversely calculated based on the results of the conventional interpretation, as shown in Table 5.

[0224] The calculated isotope front values between the casing and the formation in Table 5 are all larger than the actual values, indicating that the water absorption of Layer 7 is on the high side and there is contamination above Layer 7. By correcting the contamination correction value, the water absorption of Layer 7 is reduced. When the water absorption of each layer is as shown in Table 6, the simulated migration time of the isotope front obtained by inverse calculation is basically consistent with the measured isotope migration time, as shown in Table 7, indicating that the actual total well injection volume and the calculated water absorption of each injection layer in Table 6 are accurate. The final interpretation results are shown in Figure 6 .

[0225] Table 3 calculates the water absorption of each layer using the conventional isotope filtration product method.

[0226] Interval 1# 2# 7# Water Absorption Ratio % 9 19.6 71.4 <![CDATA[Water absorption m 3 > 5.4 11.76 42.84

[0227] Table 4 Comparison of the inverse simulated migration time and the actual logging time based on Table 3

[0228] Isotope Front Actual Logging Arrival Time (m) Simulated Calculation Arrival Time (m) Isotope Curve 1 in Tubing - Isotope Front 8 7 Isotope Curve 2 between Casing and Annulus - Isotope Front 67.7 66.8

[0229] Table 5 Comparison of the inverse simulated migration time and the actual logging time after correcting the total well injection volume

[0230] Isotope Front Actual Logging Arrival Time (m) Simulated Calculation Arrival Time (m) Isotope Curve 1 in Tubing - Isotope Front 8 8 Isotope Curve 2 between Casing and Annulus - Isotope Front 67.7 77.6

[0231] Table 6 Water absorption table for each layer

[0232] 1# 2# 7# Water Absorption Ratio % 9.83 27.03 63.14 Water Absorption Volume m3 5.21 14.33 33.47

[0233] Table 7 Comparison of the inverse simulated migration time and the actual logging time from Table 6

[0234] Isotope Front Actual Logging Arrival Time (m) Simulated Calculation Arrival Time (m) Isotope Curve 1 in Tubing - Isotope Front 8 8 Isotope Curve 2 between Casing and Annulus - Isotope Front 67.7 67.9

[0235] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0236] Except for the technical features described in the specification, the rest are known technologies to those skilled in the art.

Claims

1. A storage-type isotope water absorption profile tracking logging method, characterized in that, The storage-type isotope water absorption profile tracking logging method includes: Step 11: Prepare the relevant data for isotope water absorption profile logging; Step 12: Calculate the simulated migration time for the isotope to reach different positions downhole; Step 13: Determine the appropriate logging time for logging with reference to the simulated migration time.

2. The storage isotope water absorption profile tracing logging method according to claim 1, characterized in that, In Step 11, the relevant data for isotope water absorption profile logging includes: the logging task book, the structure and dimensions of the injection string, the perforated interval, the injection volume, the injection pressure, the ion type and salinity of the injected water.

3. The storage-type isotope water absorption profile tracing logging method according to claim 1, characterized in that, In Step 12, the simulated migration time is the time for the tracer to migrate from the release point to different positions downhole. Different positions downhole generally use the depth of downhole tools and the upper and lower bounds of the water injection layers.

4. The storage-type isotope water absorption profile tracing logging method according to claim 1, characterized in that, In Step 12, a segmented method is used to calculate the simulated migration time, including: the calculation method for the simulated migration time of a general water injection well and the calculation method for the simulated migration time of a separately-injected well.

5. The storage-type isotope water absorption profile tracing logging method according to claim 4, characterized in that In Step 12, the calculation formula for the simulated migration time of a general water injection well is: T1 i = T2 i -th i 1 << i << n T1 i : Time when the isotope migrates to the first interface of the i-th layer; T2 i : Time for the isotope to migrate to the second interface of the i-th layer; t0: The migration time from the isotope release point to the bell mouth; tl1: The migration time between the bell mouth and the first layer; th1: The migration time of the isotope within the first perforated layer; tl i : Migration time between the (i - 1)-th and the i-th isotope layers, where i ≥ 2; th i : Migration time within the i-th perforation layer of the isotope, where 1 ≤ i ≤ n; n: The total number of layers within the segment.

6. The storage-type isotope water absorption profile tracing logging method according to claim 4, characterized in that, In Step 12, the calculation formula for the simulated migration time of a separately-injected well is: T1 i = T2 i -th i 1 << i << n T1 i : Time for the isotope to migrate to the first interface of the first layer of the k-th water distributor; T2 i : Time when the isotope migrates to the second interface of the i-th layer of the k-th water distributor; th i : Migration time in the i-th perforation interval of the k-th water distributor of the isotope tl i : Migration time between the (i - 1)-th layer and the i-th layer of the k-th water distributor for isotopes, where i ≥ 2; tl1: The migration time between the k-th water distributor and the corresponding first layer; tt1: The time for the isotope to migrate from the release point Y to the first water distributor; tt j : Migration time from the (j - 1)-th water distributor to the j-th water distributor section, j ≥ 2; n: The total number of layers within the segment; m: The number of water distributors.

7. The storage isotope water absorption profile tracing logging method according to claim 1, characterized in that, In Step 12, different water absorption models are used in the calculation of the simulated migration time to change the injection volume of each layer of the water injection well, and calculate the time for the isotope to reach each layer under various conditions, providing a theoretical basis for setting the time for storage-type isotope water absorption profile logging.

8. The storage isotope water absorption profile tracing logging method according to claim 7, characterized in that In Step 12, a few typical models are used for different water absorption models. The typical models mainly include: (1) The average model: The water absorption volume of each layer is the same; (2) The uniform flow model: The injection intensity of each layer is the same; (3) The single-layer water absorption ratio longest time model: Calculate the longest tracer arrival time for each layer when the water absorption volume of each layer is a certain proportion respectively; (4) Determine the most likely water absorption ratio model based on previous years' logging data and formation characteristics, and thus obtain the probable time range for the isotope to reach each layer of the water injection well, providing a theoretical basis for setting the time for storage-type isotope water absorption profile logging.

9. The storage-type isotope water absorption profile tracing logging method according to claim 1, characterized in that In Step 13, determine the appropriate logging time for logging with reference to the simulated migration time calculated in Step 12, and record the logging curves during the downhole migration of the isotope.

10. Storage-type isotope water absorption profile tracing logging and interpretation method, characterized in that The storage-type isotope water absorption profile tracking logging and interpretation method includes: Step 21: Record the logging curves during the downhole migration of the isotope; Step 22: Judge and interpret the water absorption volume of each layer; Step 23: Inversely calculate the simulated migration time of the isotope using the water absorption volume of each layer interpreted in Step 22; Step 24: Verify the interpretation results using the simulated migration time of the isotope inversely calculated in Step 23.

11. The storage isotope water absorption profile tracing logging and interpretation method according to claim 10, characterized in that, In Step 21, during the downhole migration of the isotope, record multiple curves during the isotope migration at different time periods and the curves when the isotope is relatively stationary at each layer.

12. The storage isotope water absorption profile tracing logging and interpretation method according to claim 10, characterized in that, In Step 22, preliminarily judge and interpret the water absorption volume of each layer based on the isotope migration curve and the conventional filtering method of the isotope water absorption profile.

13. The storage-type isotope water absorption profile tracing logging and interpretation method according to claim 10, wherein In step 23, using the interpretation result of step 22, the simulated migration time of the isotope tracer reaching different positions in the wellbore is inversely calculated by the simulated migration time calculation method in step 12 of claim 1.

14. The storage isotope water absorption profile tracing logging and interpretation method according to claim 10, characterized in that, In step 24, by comparing the actual time when the isotope tracer reaches different positions in the wellbore in the logging with the simulated migration time calculated in step 23, it is verified whether the interpretation result conforms to the actual migration time law of the isotope. If it conforms, it indicates that the interpretation result conforms to the actual situation. If it does not conform, combined with other situations, the parameters are adjusted as appropriate to correct the influence of the formation pore size and isotope contamination on the data until the actual dynamic migration time and the simulated migration time are basically consistent.

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