A quinoline-based chemical tracer for multi-stage fracturing, a tracing method, a fracturing fluid and uses thereof

Abstract

The application discloses a quinoline chemical tracer for multi-stage fracturing, a tracing method, a fracturing fluid and an application. The quinoline chemical tracer for multi-stage fracturing has a structural formula as shown in the specification, wherein R1, R2, R3, R4, R5, R6 and R7 are the same or different and are independently one of H, methyl, methoxy, ethyl, ethoxy, NO2 and fluorine. The quinoline chemical tracer has the advantages of high sensitivity, low detection limit, strong temperature resistance, high stability under the conditions of room temperature to 80 DEG C and 0-50000 mg / L of mineralization degree, strong anti-adsorption capacity, no interference between each tracer, suitability for many harsh formation conditions, application in oilfield multi-stage fracturing tracing technology and potential application in interwell tracing technology.

Description

Technical Field

[0001] This invention relates to the field of oilfield drilling technology, specifically to a quinoline-based chemical tracer for multi-stage fracturing, a tracer method, a fracturing fluid, and its applications. Background Technology

[0002] Tracing technology can be divided into inter-well tracing, single-well tracing, and multi-stage fracturing tracers, depending on the application scenario. The types and performance of tracers used vary depending on the purpose of use.

[0003] Commonly used tracers in oil fields include chemical tracers, radioactive isotope tracers, non-radioactive isotope tracers, and trace substance tracers. Traditional chemical tracers are diverse, including inorganic salts, low molecular weight alcohols, and fuels. However, traditional chemical tracers suffer from drawbacks such as high dosage, high adsorption, easy degradation, and high detection limits. If these drawbacks can be overcome, chemical tracers will have new application potential. Summary of the Invention

[0004] To address the challenges of large dosage, high cost, and severe environmental pollution associated with existing oilfield tracers, this invention proposes a quinoline-based chemical tracer for multi-stage fracturing, a tracer method, a fracturing fluid, and its applications. This invention provides a quinoline-based chemical tracer with a low detection limit, suitable for inter-well tracer technology. The tracer described in this invention exhibits high stability at temperatures ranging from room temperature to 80°C and at salinity levels from 0 to 50,000 mg / L, making it suitable for many demanding formations. The quinoline-based chemical tracer of this invention possesses advantages such as strong temperature resistance, strong anti-adsorption capacity, and no interference between different components. This novel quinoline-based chemical tracer opens up a completely new category of chemical tracers and, containing an aromatic ring, possesses ultraviolet absorption properties, thus allowing for the use of more monitoring methods to identify this type of compound.

[0005] One objective of this invention is to provide a quinoline-based chemical tracer for multi-stage fracturing, with the following structural formula:

[0006]

[0007] Among them, R1, R2, R3, R4, R5, R6, and R7 may be the same or different, and are independently one of the elements H, methyl, methoxy, ethyl, ethoxy, NO2, and fluorine.

[0008] In a preferred embodiment of the present invention,

[0009] In the structural formula, R1, R2, R3, R4, R6 and R7 are all H, and R5 is one of H, methyl, methoxy, ethyl, ethoxy, NO2 and fluorine.

[0010] In a preferred embodiment of the present invention,

[0011] The quinoline chemical tracer is at least one of 4-methylquinoline, 4-methoxyquinoline, 4-fluoroquinoline, and 4-ethylquinoline.

[0012] The second objective of this invention is to provide a multi-stage fracturing tracer method using a quinoline-based chemical tracer, comprising the steps of adding the quinoline-based chemical tracer into an injection well, subsequently sampling in a monitoring well, and plotting a tracer production curve.

[0013] In a preferred embodiment of the present invention,

[0014] The quinoline-based chemical tracer is added to the injection well either as a single agent or in the form of a tracer solution.

[0015] In a preferred embodiment of the present invention,

[0016] The concentration range of the tracer solution is 0.05–500 mg / L, preferably 1–500 mg / L, and more preferably 1–50 mg / L.

[0017] In a preferred embodiment of the present invention,

[0018] The method includes:

[0019] (1) Select a tracer that matches the fracturing conditions;

[0020] (2) Calculate and determine the amount of tracer based on the number of fracturing stages, the instrument's minimum detection limit, the amount of fracturing fluid used, and the formation properties;

[0021] (3) The tracer is injected along with the fracturing fluid during the fracturing process;

[0022] (4) Sampling is carried out at monitoring wells, with a sampling cycle of 15 to 60 days;

[0023] (5) Standardize the processing, detection and analysis of the samples, and plot the tracer production curve.

[0024] In a preferred embodiment of the present invention,

[0025] In step 4), a peristaltic pump can be used during the injection process to inject the tracer together with the fracturing fluid.

[0026] The present invention can specifically adopt the following technical solutions:

[0027] 1) Analyze the fracturing fluid and produced water of the oilfield and select tracers for the formation. The tracers used for the formation are selected from compounds that are not contained in the formation.

[0028] 2) Design and implementation plan;

[0029] 3) Calculate the amount of tracer to be added: Based on the number of fracturing stages, the instrument's minimum detection limit, the amount of fracturing fluid used, and the formation properties, calculate and determine the amount of tracer to be added;

[0030] 4) Use pump trucks or other equipment to inject tracers along with the fracturing fluid during the fracturing process;

[0031] 5) Sampling shall be carried out in accordance with the established sampling system, with a sampling cycle of 15 to 60 days;

[0032] 6) Standardize the samples;

[0033] 7) Detect and analyze the produced fluid using appropriate analytical methods; the analytical methods used are conventional analytical methods in this field;

[0034] 8) Plot the tracer production curve;

[0035] 9) Simulation calculations were performed using conventional tracer numerical modeling software;

[0036] 10) Complete the comprehensive analysis and testing report.

[0037] A third objective of this invention is to provide a fracturing fluid containing a quinoline-based chemical tracer, which is one of the objectives of this invention.

[0038] In a preferred embodiment of the present invention,

[0039] The amount of the quinoline-based chemical tracer used is 0.0005 to 0.05 wt% of the fracturing fluid, preferably 0.005 to 0.01 wt%.

[0040] The fourth objective of this invention is to provide an application of the fracturing fluid of the third objective of this invention in multi-stage fracturing.

[0041] The fifth objective of this invention is to provide a use of quinoline compounds as chemical tracers in multi-stage fracturing, wherein the structural formula of the quinoline compound is as follows:

[0042]

[0043] Among them, R1, R2, R3, R4, R5, R6, and R7 may be the same or different, and are independently one of the elements H, methyl, methoxy, ethyl, ethoxy, NO2, and fluorine.

[0044] In a preferred embodiment of the present invention,

[0045] In the structural formula, R1, R2, R3, R4, R6 and R7 are all H, and R5 is one of H, methyl, methoxy, ethyl, ethoxy, NO2 and fluorine.

[0046] In a preferred embodiment of the present invention,

[0047] The quinoline compound is at least one of 4-methylquinoline, 4-methoxyquinoline, 4-fluoroquinoline, and 4-ethylquinoline.

[0048] In a preferred embodiment of the present invention,

[0049] The described use includes the steps of adding the quinoline compound as a tracer into the injection well, subsequently sampling in the monitoring well, and plotting the tracer production curve; preferably,

[0050] The quinoline compounds are added to the injection well either alone or in solution form; and / or

[0051] The concentration range of the solution is 0.05–500 mg / L, preferably 1–500 mg / L, and more preferably 1–50 mg / L.

[0052] The beneficial effects of this invention are:

[0053] The novel quinoline-based chemical tracers of this invention exhibit high detection sensitivity and low detection limits. Each tracer does not interfere with the others, making them suitable for use in multi-stage fracturing tracer technology in oilfields and also possessing potential for application in inter-well tracer technology. Excessive usage can easily lead to reservoir formation contamination. The novel quinoline-based chemical tracers of this invention require smaller dosages, with a detection limit as low as 0.05 mg / L, significantly reducing the amount of tracers used in oilfields. These novel quinoline-based chemical tracers of this invention open up a completely new category of chemical tracers and, containing aromatic rings, possess properties such as ultraviolet absorption, thus allowing for the use of more monitoring methods to identify this type of compound. Attached Figure Description

[0054] Figure 1 This is the analytical standard curve obtained from the detection limit experiment using 4-methylquinoline in Example 6;

[0055] The horizontal axis represents the concentration of a single tracer (mg / L), and the vertical axis represents the peak area on the chromatogram (Au*min). Detailed Implementation

[0056] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0057] All raw materials used in the examples are commercially available, and some of the raw materials are sourced from the following sources:

[0058] 4-Methylquinoline CAS: 491-35-0, Brand: Maclean

[0059] 4-Methoxyquinoline CAS: 607-31-8, Brand: Shanghai Yuanye Biotechnology

[0060] 4-Fluoroquinoline CAS: 394-70-7, Brand: Bailingwei

[0061] 4-Ethylquinoline CAS: 19020-26-9, Brand: MOLCORE

[0062] In this invention, the quinoline-based chemical tracer used for multi-stage fracturing has the following structural formula:

[0063]

[0064] Wherein, R1, R2, R3, R4, R5, R6, and R7 may be the same or different, and are independently one of the elements H, methyl, methoxy, ethyl, ethoxy, NO2, and fluorine; preferably,

[0065] In the above structural formula, R1, R2, R3, R4, R6, and R7 are all H, and R5 is one of H, methyl, methoxy, ethyl, ethoxy, NO2, and fluorine; more preferably,

[0066] The quinoline chemical tracer is at least one of 4-methylquinoline, 4-methoxyquinoline, 4-fluoroquinoline, and 4-ethylquinoline.

[0067] Specific examples of the above-mentioned quinoline-based chemical tracers are as follows:

[0068] Example 1

[0069] The experimental samples were prepared as a n-octane solution with a concentration of approximately 100 mg / L and aged at 80°C in a 50 mL pressure vessel. Samples were taken after 60 days of aging for concentration testing, and the retention rate was calculated. The experimental results are shown in Table 1.

[0070] Table 1

[0071]

[0072] Example 2

[0073] The experimental sample was prepared as a n-octane solution with a concentration of approximately 100 mg / L, and then salt solutions of different salinities were added at a volume ratio of 1:1. The solution was aged at 80°C in a 50 mL pressure vessel for 30 days. Samples were taken for concentration testing, and the retention rate was calculated. The experimental results are shown in Table 2. The table shows that this type of tracer exhibits high salt tolerance and maintains consistent stability under different salinities.

[0074] Table 2

[0075]

[0076] Example 3

[0077] Static adsorption experiments were conducted using a mixed solution of four tracers at 100 mg / L, and the results are shown in Table 3. In quartz sand or kaolin, the adsorption capacity of these tracers was less than 0.5 mg / g, which is low and avoids significant tracer loss in the formation.

[0078] Table 3

[0079]

[0080] Example 4

[0081] Quinoline tracers were prepared into a mixed solution using n-octane, with each sample concentration of 100 mg / L. The mixed solution was then analyzed using liquid chromatography. The aim was to determine whether these tracers interfered with each other and affected the detection results. The experimental results are shown in Table 4. The results indicate that the detection results of this type of tracer in the mixed solution are close to those of the prepared concentration, demonstrating that the mutual interference between these tracers is minimal.

[0082] Table 4

[0083]

[0084] Example 5

[0085] The experimental sample was prepared as a n-octane solution with a concentration of approximately 100 mg / L and a displacement experiment was conducted at 80°C using an artificial core with a permeability of 500 mD. A fixed volume of solution was injected into the core, and the produced fluid was collected for concentration analysis. The retention rate of this type of tracer during the displacement experiment was calculated. The displacement experiment results show that the adsorption capacity of this type of tracer in the core is relatively low, indicating its potential as a tracer.

[0086] Table 5

[0087]

[0088] Example 6

[0089] 4-Methylquinoline was selected for detection limit experiments. Seven different concentrations of tracer solutions (0.05, 0.1, 1.0, 2.5, 5, 10, and 25 mg / L) were prepared, and HPLC-MS was used for detection. An analytical standard curve for this compound was constructed. Specific experimental results are shown in [link to results]. Figure 1 .Depend on Figure 1 It can be seen that this type of tracer has a good linear relationship, can be quantitatively analyzed and monitored, and has a detection limit of less than 0.05 mg / L. Therefore, the detection limit of the method used is at least 0.05 mg / L.

[0090] As can be seen from Examples 1-6, the quinoline-based chemical tracers of the present invention are highly sensitive and have a low detection limit, reaching 0.05 mg / L. They also exhibit strong temperature resistance, demonstrating high stability at temperatures ranging from room temperature to 80 degrees Celsius and at mineralization levels from 0 to 50,000 mg / L. Furthermore, they possess strong anti-adsorption capabilities, and each tracer does not interfere with the others. They are suitable for formations with many harsh conditions and can be used in oilfield multi-stage fracturing tracer technology, with the potential to be applied in inter-well tracer technology.

[0091] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0092] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0093] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0094] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0095] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0096] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A multi-stage fracturing tracer method using quinoline-based chemical tracers, comprising the steps of adding the quinoline-based chemical tracer into an injection well, subsequently sampling in a monitoring well, and plotting a tracer production curve; The quinoline-based chemical tracer has the following structural formula: ； in, R1, R2, R3, R4, R6, and R7 are all H, and R5 is one of H, methyl, methoxy, ethyl, ethoxy, NO2, or fluorine.

2. The method as described in claim 1, characterized in that: The quinoline chemical tracer is at least one of 4-methylquinoline, 4-methoxyquinoline, 4-fluoroquinoline, and 4-ethylquinoline.

3. The method as described in claim 1, characterized in that: The quinoline-based chemical tracer is added to the injection well either alone or in the form of a tracer solution.

4. The method as described in claim 3, characterized in that: The concentration range of the tracer solution is 0.05~500 mg / L.

5. The method as described in claim 4, characterized in that: The concentration range of the tracer solution is 1~500 mg / L.

6. The method as described in claim 5, characterized in that: The concentration range of the tracer solution is 1~50 mg / L.

7. The method according to any one of claims 1 to 6, characterized in that... The method includes: (1) Select a tracer that matches the fracturing conditions; (2) Calculate and determine the amount of tracer based on the number of fracturing stages, the instrument's minimum detection limit, the amount of fracturing fluid used, and the formation properties; (3) The tracer is injected along with the fracturing fluid during the fracturing process; (4) Sampling is carried out at the monitoring wells, with a sampling period of 15 to 60 days; (5) Standardize the processing, detection and analysis of the samples, and plot the tracer production curve.

8. A fracturing fluid comprising the fluid as claimed in claim 1 7. Quinoline-based chemical tracers as described in any of the above.

9. The fracturing fluid as described in claim 8, characterized in that: The amount of the quinoline-based chemical tracer used is 0.0005~0.05 wt% of the fracturing fluid.

10. The fracturing fluid as described in claim 9, characterized in that: The amount of the quinoline-based chemical tracer used is 0.005~0.01 wt% of the fracturing fluid.

11. A method as claimed in claim 8 Application of any of the fracturing fluids described in 10 in multi-stage fracturing.

12. The use of a quinoline compound as a chemical tracer for multi-stage fracturing, said quinoline compound having the following structural formula: ； in, R1, R2, R3, R4, R6, and R7 are all H, and R5 is one of H, methyl, methoxy, ethyl, ethoxy, NO2, or fluorine.

13. The use as described in claim 12, characterized in that: The quinoline compound is at least one of 4-methylquinoline, 4-methoxyquinoline, 4-fluoroquinoline, and 4-ethylquinoline.

14. The use as described in any one of claims 12-13, characterized in that: The method includes the steps of adding the quinoline compound as a tracer into the injection well, then sampling in the monitoring well, and plotting the tracer production curve.

15. The use as described in claim 14, characterized in that: The quinoline compounds are added to the injection well either alone or in solution form; and / or The concentration range of the solution is 0.05~500 mg / L.

16. The use as described in claim 15, characterized in that: The concentration range of the solution is 1~500 mg / L.

17. The use as described in claim 16, characterized in that: The concentration range of the solution is 1~50 mg / L.

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