An organic tracer, its preparation and a method for interwell tracing, and the use of polycyclic fatty ether compounds as organic tracers

Abstract

The present application relates to oilfield tracer technical field, disclose a kind of organic tracer and its preparation and interwell tracing method and the use of polycyclic fatty ether compound as organic tracer.The polycyclic fatty ether compound is used as organic tracer in the present application, and the interwell tracing method includes calculating and determining the dosage of organic tracer;Organic tracer is injected together with fracturing fluid during use;Sampling is carried out in monitoring well;Sample is standardized, detected and analyzed, and the output curve of organic tracer is drawn.The selected polycyclic fatty alcohol ether chemical tracer has the advantages of low dosage, small adsorption, high stability and low detection limit, and can be used for interwell tracing technology, effectively solving the problems of large dosage, high cost and serious environmental pollution of existing oilfield tracer.

Description

Technical Field

[0001] This invention relates to the field of oilfield tracer technology, and more specifically, to an organic tracer, its preparation method, an inter-well tracer method, and the use of polycyclic aliphatic ether compounds as organic tracers. 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] According to existing technology, as described in "Oilfield Tracer Technology" (Industrial Water Treatment, August 2007, Vol. 27, No. 8, Yu Ruixiang et al.), commonly used tracers in oilfields 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, existing chemical tracers suffer from drawbacks such as high dosage, large adsorption, easy degradation, and high detection limits. Further development of new chemical tracers is needed to overcome these shortcomings and thus enhance their application potential. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes an organic tracer, its preparation method, an inter-well tracking method, and the use of polycyclic aliphatic ether compounds as organic tracers. This invention discovers that the selected polycyclic aliphatic alcohol ether compounds as organic tracers have advantages such as low dosage, low adsorption, high stability, and low detection limit, enabling their use in inter-well tracking technology and effectively solving the problems of large dosage, high cost, and serious environmental pollution associated with existing oilfield tracers.

[0005] To solve the above technical problems, the present invention adopts the following technical solution.

[0006] One object of the present invention is to provide an organic tracer comprising at least one of polycyclic aliphatic ether compounds.

[0007] In the organic tracer described in this invention, preferably,

[0008] The polycyclic aliphatic ether compounds are aliphatic alcohol ether compounds containing a bridged ring structure.

[0009] Preferably,

[0010] The general structural formula of the fatty alcohol ether compounds containing the bridged ring structure is as follows:

[0011]

[0012] Wherein, (R1)n represents n R1 substituents on the bridge ring, and the n R1 substituents are the same or different, each independently selected from H, C1-C4 alkyl (such as methyl, ethyl, propyl, butyl), C1-C4 alkoxy, carbonyl or halogen.

[0013] The value of n is in the range of 0-9, preferably 0-5, more preferably 0-3, for example, it can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9; and when there are multiple R1 substituents, the R1 substituents can be attached to different carbon atoms respectively, or two carbon atoms can be attached to the same carbon atom.

[0014] R2 and R3 may be the same or different, and each is independently selected from hydrogen and C1-C4 alkyl groups.

[0015] In this invention, R1 substituent refers to the group that replaces the hydrogen atom on the bridge ring. That is, unless otherwise specified in this invention, there are no other substituents on the bridge ring except for R1, R2, and R3, and all of them are hydrogen atoms.

[0016] Preferably,

[0017] The C1-C4 alkyl groups are selected from either methyl or ethyl;

[0018] The alkoxy groups of C1-C4 are selected from either methoxy or ethoxy groups;

[0019] The halogen is selected from fluorine.

[0020] Preferably,

[0021] The fatty alcohol ether compounds containing bridged ring structures are selected from:

[0022] At least one of them.

[0023] Preferably,

[0024] The organic tracer also contains a solvent.

[0025] Preferably,

[0026] The solvent is an organic solvent, and more preferably, the organic solvent is selected from at least one of n-octane, ethyl acetate, ethanol or tetrahydrofuran.

[0027] Preferably,

[0028] The concentration range of the polycyclic aliphatic ether compound in the solvent is 0.5 wt% to 10 wt%.

[0029] In this invention, other substances commonly used in the art can also be added to the organic tracer according to the application requirements.

[0030] A second objective of this invention is to provide a method for preparing the organic tracer described in one objective of this invention. The preparation method includes the following steps: mixing a polycyclic aliphatic ether compound and optionally a solvent evenly to obtain the organic tracer.

[0031] A third objective of this invention is to provide an inter-well tracking method for the organic tracer described in one objective of this invention, wherein the inter-well tracking method includes:

[0032] The organic tracer was added to the injection well, and samples were then taken from the production well to plot the tracer production curve.

[0033] Preferably, the well-to-well tracing method includes:

[0034] (1) Calculate and determine the amount of organic tracer based on the average effective thickness of the oil layer, the porosity of the oil layer, the water saturation of the oil layer, the injection-production well spacing, and the highest value of the organic tracer production concentration.

[0035] (2) The organic tracer is injected together with the fracturing fluid during use;

[0036] (3) Take samples from the monitoring well;

[0037] (4) Standardize the processing of the samples, perform detection and analysis, and plot the production curve of the organic tracer.

[0038] Preferably, the formula for calculating the amount of the organic tracer is as follows:

[0039]

[0040] Where h is the average effective thickness of the oil layer, in meters; —Reservoir porosity, measured in darcy; S w —Water saturation of the oil reservoir, in %; C p，max —The highest concentration of the organic tracer produced (generally taken as more than 10 times the lowest detection limit concentration based on experience), in mg / L; α—Dispersion constant, wherein the value of α is 0.0005-0.003, preferably 0.001; L—Injection-production well distance, in m; m—Tracer dosage, in kg; and / or,

[0041] The sampling period for step (3) is 30 to 180 days.

[0042] In this invention, the typical dosage of the organic tracer is approximately tens to hundreds of kilograms. The organic tracer can be added to the injection well either as a single agent or in the form of a solution; the concentration of the organic tracer injected with the fracturing fluid needs to be determined according to the detection method, and it should meet the detection limit of the detection method.

[0043] More preferably, the present invention can specifically adopt the following technical solutions:

[0044] 1) Analyze the oilfield produced fluids and select tracers for the formation. The tracers for the formation are selected from compounds that are not present in the formation.

[0045] 2) Design and implementation plan;

[0046] 3) Calculate the amount of tracer to be added;

[0047] 4) Inject organic tracers into injection wells using pump trucks or other equipment;

[0048] 5) Take samples from the monitoring wells according to the established sampling procedure;

[0049] 6) Standardize the samples;

[0050] 7) Detect and analyze the produced fluid using appropriate analytical methods; the analytical methods used are conventional analytical methods in this field;

[0051] 8) Plot the tracer production curve;

[0052] 9) Simulation calculations were performed using conventional tracer numerical modeling software;

[0053] 10) Complete the comprehensive analysis and testing report.

[0054] A fourth objective of this invention is to provide the use of polycyclic aliphatic ether compounds as organic tracers, wherein the polycyclic aliphatic ether compounds are preferably fatty alcohol ether compounds containing a bridged ring structure; more preferably,

[0055] The general structural formula of the fatty alcohol ether compounds containing the bridged ring structure is as follows:

[0056]

[0057] Wherein, (R1)n represents n R1 substituents on the bridge ring, and the n R1 substituents are the same or different, each independently selected from one of C1-C4 alkyl, C1-C4 alkoxy, carbonyl or halogen;

[0058] The value of n ranges from 0 to 9, preferably from 0 to 5, and more preferably from 0 to 3;

[0059] R2 and R3 may be the same or different, and each is independently selected from hydrogen and C1-C4 alkyl groups.

[0060] In the intended use described in this invention, preferably,

[0061] The C1-C4 alkyl group is selected from one of methyl or ethyl; and / or,

[0062] The C1-C4 alkoxy groups are selected from one of methoxy or ethoxy; and / or,

[0063] The halogen is selected from fluorine.

[0064] In the intended use described in this invention, preferably,

[0065] The fatty alcohol ether compounds containing bridged ring structures are selected from:

[0066] At least one of them.

[0067] In the intended use described in this invention, preferably,

[0068] The organic tracer further comprises a solvent; the solvent is preferably an organic solvent, more preferably, the organic solvent is selected from at least one of n-octane, ethyl acetate, ethanol or tetrahydrofuran; most preferably, the concentration of the polycyclic aliphatic ether compound in the solvent is in the range of 0.5 wt% to 10 wt%.

[0069] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. 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 the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0070] Compared with the prior art, the present invention has at least the following advantages:

[0071] This invention discovers that fatty alcohol ether compounds containing bridged ring structures can be used as inter-well tracers. When used as organic tracers, they are highly sensitive and have low detection limits. Each tracer does not react directly with the others and does not interfere with each other, making them suitable for inter-well tracer technology in oil fields.

[0072] The organic tracer of the present invention requires a small dosage and the detection limit can reach 0.1 mg / L, which greatly reduces the amount of tracer used in oil fields. Excessive use can easily cause oil reservoir formation pollution. Attached Figure Description

[0073] Figure 1 This is the standard curve for the sensitivity detection of the organic tracer of the present invention;

[0074] Figure 2The results are from the sampled fluid during the field application of the organic tracer of the present invention.

[0075] in Figure 1 The unit of peak area is AU*min;

[0076] Figure 2 In the table, oiltracer1 represents the detection result of the organic tracer corresponding to compound 1, and oiltracer2 represents the detection result of the organic tracer corresponding to compound 3. Detailed Implementation

[0077] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. 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.

[0078] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0079] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0080] The raw materials used in the examples and comparative examples are all disclosed in the prior art and are commercially available; they can also be prepared according to the preparation methods disclosed in the prior art.

[0081] The formula for calculating the retention rate of organic tracers is: C 现有浓度 / C 初始浓度 C 现有浓度 C 初始浓度 HPLC-MS was used for detection.

[0082] Example 1

[0083] Prepare 100 mg / L n-octane solutions of the tracers listed in the table below, age them at 70°C in 50 mL pressure-bearing bombs, and take samples after 60 days of aging for concentration testing. Calculate the retention rate using the formula: C 现有浓度 / C 初始浓度 The experimental results are shown in Table 1:

[0084] Table 1

[0085]

[0086] Example 2

[0087] The tracers listed in the table below were prepared into 100 mg / L n-octane solutions, and salt solutions with different salinities were added, with a volume ratio of tracer solution to salt solution of 1:1. The solutions were aged at 70°C in a 50 mL pressure vessel for 30 days. Samples were taken for concentration testing, and the retention rate was calculated using the same formula as in Example 1. The experimental results are shown in Table 2. Table 2 shows that this type of tracer exhibits high salt tolerance and maintains consistent stability under different salinities.

[0088] Table 2

[0089]

[0090]

[0091] Example 3

[0092] Static adsorption experiments were conducted using a mixed solution of the following tracers prepared with n-octane, with each tracer sample having a concentration of 100 mg / L in the mixed solution; the results are shown in Table 3. In quartz sand or kaolin, the adsorption capacity of this type of tracer was less than 0.1 mg / g, which is low and avoids significant tracer loss in the formation.

[0093] Table 3

[0094]

[0095]

[0096] Example 4

[0097] The following tracers were prepared into a mixed solution using n-octane, with each tracer sample having a concentration of 100 mg / L. The mixed solution was then analyzed using liquid chromatography. The study aimed to determine whether these tracers would interfere with each other and affect 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.

[0098] Table 4

[0099]

[0100] Example 5

[0101] The following tracers were prepared into n-octane solutions with a concentration of approximately 100 mg / L and observed at 80°C to determine whether precipitation occurred. After 24 hours of high-temperature aging, the experimental results are shown in Table 5. The results indicate that these tracers have high solubility and do not precipitate.

[0102] Table 5

[0103]

[0104] Example 6

[0105] The tracers described below were prepared into n-octane solutions with a concentration of approximately 100 mg / L. Displacement experiments were conducted at 70°C using artificial cores 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 the tracers during the displacement experiments was calculated, and the experimental results are shown in Table 6. The displacement experiment results show that the organic tracers of this invention have low adsorption capacity in the core, indicating their potential as inter-well tracers.

[0106] Table 6

[0107]

[0108]

[0109] Example 7

[0110] Prepare n-octane solutions of approximately 100 mg / L using the tracers listed in the table below, adjusting the pH to 6.4 and 10.6 (using commonly available pH adjusters, such as very dilute sodium hydroxide solution). Aging is carried out at 70°C in a 50 mL pressure vessel. Samples are taken after 60 days of aging for concentration testing, and the retention rate is calculated using the formula: C 现有浓度 / C 初始浓度 The experimental results are shown in Table 7:

[0111] Table 7

[0112]

[0113] Example 8

[0114] The detection limit experiment was conducted using the organic tracer corresponding to compound 1. Nine different concentrations of the organic tracer solution were prepared: 0.05, 0.1, 0.3, 0.5, 1.0, 2.5, 5, 10, 25, and 50 mg / L. HPLC-MS was used for detection, and an analytical standard curve for this compound was constructed. Specific experimental results are shown in [link to results]. Figure 1 .

[0115] In the present invention Figure 1As can be seen, when the concentration of the prepared solution is further diluted from 0.1 mg / L to 0.05 mg / L, the linear trend is still observed at this concentration. However, the peak area is too low at lower concentrations, making accurate integration impossible. Therefore, the limit of detection is considered to be 0.1 mg / L.

[0116] Example 9

[0117] Field application experiment:

[0118] Two tracers were selected from two fracture sections at a fracturing site in a Shengli oilfield:

[0119] The first tracer is compound 1, and the second tracer is compound 3. Both are added to two fracture sections, one tracer for each section. The volume of fracturing fluid used in each section is 200 cubic meters. The formula for calculating the tracer dosage is as follows:

[0120]

[0121] Where h is the average effective thickness of the oil layer, in meters; —Reservoir porosity, measured in darcy (S) w —Water saturation of the oil reservoir, in %; C p，max —The highest concentration of the organic tracer produced (taken as 10 times the lowest detection limit), in mg / L; α—dispersion constant, where α is 0.001; L—injection-production well distance, in m; Calculations show that 10 kg of tracer is added to 200 cubic meters of fracturing fluid, and the tracer is injected along with the fracturing fluid. During production, samples are taken periodically for testing, with a sampling period of 30 days, and curves are plotted. The crude oil portion of the produced fluid is taken for pretreatment and HPLC-MS analysis to determine the tracer concentration. The produced fluid test results are shown below. Figure 2 .Depend on Figure 2 As can be seen from this, the backflow of the fracturing was good, and the injected tracer was detected on the 6th day.

[0122] The results above show that the organic tracer of the present invention has the advantages of low dosage, low adsorption, high stability, and low detection limit. It can be used in inter-well tracer technology and effectively solves the problems of large dosage, high cost, and serious environmental pollution of existing oilfield tracers.

[0123] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. The use of a polycyclic aliphatic ether compound as an organic tracer, characterized in that, The polycyclic aliphatic ether compounds are aliphatic alcohol ether compounds containing a bridged ring structure; The general structural formula of the fatty alcohol ether compounds containing the bridged ring structure is as follows: ； Wherein, (R1)n represents n R1 substituents on the bridge ring, and the n R1 substituents are the same or different, each independently selected from one of C1-C4 alkyl, C1-C4 alkoxy, and carbonyl groups; The value of n ranges from 0 to 3; R2 and R3 may be the same or different, and each is independently selected from hydrogen and C1-C4 alkyl groups.

2. The use according to claim 1, characterized in that, The C1-C4 alkyl group is selected from one of methyl or ethyl; and / or, The alkoxy groups of C1-C4 are selected from either methoxy or ethoxy.

3. The use of a polycyclic aliphatic ether compound as an organic tracer, characterized in that, The fatty alcohol ether compounds containing bridged ring structures are selected from: , , , , , or At least one of them.

4. The use according to claim 1 or 3, characterized in that, The organic tracer also contains a solvent.

5. The use according to claim 4, characterized in that, The solvent is an organic solvent.

6. The use according to claim 5, characterized in that, The organic solvent is selected from at least one of n-octane, ethyl acetate, ethanol, or tetrahydrofuran.

7. The use according to claim 6, characterized in that, The concentration range of the polycyclic aliphatic ether compound in the solvent is 0.5wt% to 10wt%.

8. An organic tracer comprising a solvent and a polycyclic aliphatic ether compound; wherein the polycyclic aliphatic ether compound is a fatty alcohol ether compound containing a bridged ring structure; the general structural formula of the fatty alcohol ether compound containing the bridged ring structure is as follows: ； in, (R1)n represents n R1 substituents on the bridge ring, and the n R1 substituents are the same or different, each independently selected from one of C1-C4 alkyl, C1-C4 alkoxy, and carbonyl groups; The value of n ranges from 0 to 3; R2 and R3 may be the same or different, and each is independently selected from hydrogen and C1-C4 alkyl groups.

9. The organic tracer according to claim 8, characterized in that, The C1-C4 alkyl group is selected from one of methyl or ethyl; and / or, The alkoxy groups of C1-C4 are selected from either methoxy or ethoxy.

10. An organic tracer, characterized in that, The organic tracer comprises a solvent and a polycyclic aliphatic ether compound; The fatty alcohol ether compounds containing bridged ring structures are selected from: , , , , , or At least one of them.

11. The organic tracer according to claim 8 or 10, characterized in that, The solvent is an organic solvent.

12. The organic tracer according to claim 11, characterized in that, The organic solvent is selected from at least one of n-octane, ethyl acetate, ethanol, or tetrahydrofuran.

13. The organic tracer according to claim 12, characterized in that, The concentration range of the polycyclic aliphatic ether compound in the solvent is 0.5wt% to 10wt%.

14. The method for preparing the organic tracer according to any one of claims 8-10 and 12-13, wherein the preparation method comprises the following steps: The organic tracer is prepared by uniformly mixing a polycyclic aliphatic ether compound with an optional solvent.

15. The method for inter-well tracking of an organic tracer according to any one of claims 8-10 and 12-13, comprising: The organic tracer was added to the injection well, and samples were then taken from the production well to plot the tracer production curve.

16. The well-to-well tracing method according to claim 15, characterized in that, Well-to-well tracing methods include: (1) Calculate and determine the amount of organic tracer to be added based on the average effective thickness of the oil layer, the porosity of the oil layer, the water saturation of the oil layer, the injection-production well spacing, and the highest value of the organic tracer production concentration. (2) During use, the organic tracer is injected together with the fracturing fluid; (3) Sampling was taken from the monitoring well; (4) Standardize the processing of the samples, perform detection and analysis, and plot the production curve of the organic tracer.

17. The well-to-well tracing method according to claim 16, characterized in that: The sampling period for step (3) is 30 to 180 days.

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