A delayed tracer capsule and method of use thereof

Abstract

The application discloses a delayed tracer capsule and a use method thereof, and belongs to the technical field of oilfield production dynamic monitoring. The delayed tracer capsule and the use method thereof disclosed by the application can gather solid tracers and strong magnetic particles in the capsule body, can place the tracers in a target layer without polluting a wellbore, can accurately extract a tracer base of a workover well, and can effectively prevent the inaccuracy of base recording caused by the injection of common tracers, and cannot judge whether sealing is successful. The application can accurately judge whether sealing of a casing damage sealing well is successful, and provides data support for the next measures of an oil production well.

Description

Technical Field

[0001] This invention belongs to the field of oilfield production dynamic monitoring technology, specifically relating to a deferred tracer capsule and its usage method. Background Technology

[0002] Tracer monitoring technology is widely used in the dynamic analysis of injection-production well groups, and can effectively determine connectivity relationships. Generally, tracer inter-well monitoring technology involves injecting one or more water-soluble tracers either generally or in layers into the injection well, sampling surrounding wells expected to be connected, analyzing the tracer concentration in the water samples, plotting tracer production curves based on the detection results, and using tracer interpretation software to fit and analyze the tracer production curves to interpret reservoir parameters, thereby obtaining information about reservoir heterogeneity.

[0003] With the development of fracturing technology, tracers are used to assess fracture closure in fracturing wells. In multi-stage fracturing operations, different tracers are typically injected into the fracturing fluid in stages to reach different fracturing sections. The tracers flow into the fracture along with the fracturing fluid. After fracturing, the tracers are flowed back along with the fracturing fluid and subsequent well production. The tracer concentration is periodically sampled at the surface. By classifying and analyzing the tracer samples in the produced fluid and measuring their concentration, a curve showing the tracer flowback concentration over time can be obtained. This flowback concentration curve is often used to evaluate the fracturing fluid flowback efficiency, cleaning efficiency, and the production contribution rate of each fracturing stage. Furthermore, since different characteristic parameters of the post-fracturing fracture lead to different tracer flowback concentration curves, the tracer flowback concentration curve also contains, to some extent, the parametric characteristics of the post-fracturing fracture. Analyzing tracer flowback curves and using theoretical research and practical field applications to inversely calculate post-fracturing fracture morphology, obtain relevant fracture parameters, and calculate production capacity can be used to evaluate various fracturing parameters (physical and mechanical parameters of the fracturing section), guiding reservoir evaluation, geological design, fracturing design, and the design of reasonable operating procedures. Regarding the use of tracers, patent CN202011005732.1 describes injecting the dissolved tracer into the formation from the injection well and extracting it from the production well to monitor well connectivity. Patent CN201910645239.7 aims to prevent secondary contamination during transportation, packaging, and use through a completely sealed process.

[0004] However, in older oilfields that have been developed for many years, many wells suffer from casing damage due to the long time the casing has been in the well. Casing damage is the result of a combination of physical and chemical factors, manifesting as plastic deformation, rupture, or corrosion perforation of the casing during development due to external forces or corrosion. Water seepage from the damaged point can lead to sudden water flooding of the oil well, severely restricting normal production. To ensure normal production, cementing and packers are typically used to seal the damaged points, but the success of the sealing cannot be determined. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a delayed tracer capsule and its usage method to solve the technical problem that it is impossible to accurately determine whether the plugging is successful during oil production.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] The present invention discloses a delayed tracer capsule, comprising a solid tracer 2, strong magnetic particles 3 and a capsule body 1. The solid tracer 2 and the strong magnetic particles 3 are mixed and aggregated in the capsule body 1, and the volume ratio of the solid tracer 2 to the strong magnetic particles 3 is 2:1 to 3:1.

[0008] Furthermore, the capsule 1 dissolves in 5-7 days at the target layer temperature, releasing the solid tracer 2 from the capsule 1.

[0009] Furthermore, the temperature of the target layer is 100~120℃.

[0010] Furthermore, the temperature of the target layer is 60~70℃.

[0011] The present invention also discloses a method for using the above-mentioned delayed tracer capsule, comprising the following steps:

[0012] The delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then it is lowered into the well to plug the casing layer.

[0013] Furthermore, there are multiple deferred tracer capsules placed between the dual packers 4.

[0014] Furthermore, if the water cut of the well where the casing has been plugged increases after the deferred tracer capsule dissolves in the well, the tracer content can be detected at the wellhead to determine whether the double-sealing has failed.

[0015] Furthermore, the temperature of the sealing layer is 110°C.

[0016] Furthermore, the double packer 4 is located between the tubing 5 and the casing 6 in the well.

[0017] Furthermore, the double packer 4 is located above the casing perforation 7.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention discloses a delayed tracer capsule, which aggregates a solid tracer and strong magnetic particles within the capsule body. This allows for tracer delivery to the target formation without contaminating the wellbore, accurately extracting the tracer substrate from the working well. This effectively prevents inaccurate substrate acquisition during conventional tracer injection, thus avoiding the inability to determine successful plugging. When the delayed tracer capsule is placed at the location of a double-sealing casing failure, after a period of time, the capsule dissolves and accumulates between the two seals. If the water cut in the well suddenly increases, the tracer content at the wellhead can be detected to determine whether the double-sealing has failed.

[0020] This invention also discloses a method for using the aforementioned delayed tracer capsules. Strong magnetic particles are mixed into the capsule tracer, causing the capsule tracer to be strongly adsorbed onto the tubing between the two seals at the surface. When the tubing is lowered, the tracer is lowered into the well along with the tubing, thereby accurately lowering it to a predetermined position between the two seals. The presence or absence of a double seal plugging failure can be determined by detecting the tracer content at the wellhead. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the delayed tracer capsule of the present invention;

[0022] Figure 2 This is a schematic diagram showing the state of the delayed tracer capsule of the present invention during use;

[0023] Figure 3 This is a flowchart illustrating the use of the delayed tracer capsules of the present invention.

[0024] Wherein: 1-capsule body; 2-solid tracer; 3-strong magnetic particles; 4-double packer; 5-oil pipe; 6-casing; 7-casing perforation. Detailed Implementation

[0025] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0026] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0027] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0028] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0029] like Figure 1 As shown, the present invention provides a delayed tracer capsule, comprising a solid tracer 2, strong magnetic particles 3 and a capsule body 1, wherein the solid tracer 2 and the strong magnetic particles 3 are mixed and aggregated inside.

[0030] When in use, depending on the temperature of the oil and gas reservoir, capsule 1 can dissolve in 5-7 days at the target layer temperature, releasing the solid tracer 2 inside capsule 1.

[0031] Meanwhile, the powerful magnetic particles 3 in the capsule 1 can be adsorbed onto the tubing between the double packers 4 before deployment, and then lowered into the well along with the tubing to accurately reach the designated position between the double packers.

[0032] In use, the delayed tracer capsule of this invention does not enter the formation but remains between the two packers 4, primarily for monitoring packer failure. This allows for accurate assessment of the success of well sealing due to casing damage, providing data support for subsequent well operations.

[0033] like Figure 2 As shown, the delayed tracer capsule is positioned between the two packers 4 during use. The two packers 4 are located between the tubing 5 and the casing 6 in the well, in the casing damage sealing layer. At the same time, the two packers 4 are located above the casing perforation 7.

[0034] like Figure 3 As shown, this invention also discloses a method for using the aforementioned delayed tracer capsule. The delayed tracer capsule disclosed in this invention is designed for determining whether a double-sealing blockade has failed, and includes the following steps:

[0035] S1: First, place the capsule body 1 between the double packers 4;

[0036] S2: Subsequently, due to the action of the strong magnetic particles 3, the capsule 1 is adsorbed onto the column between the double packers 4;

[0037] S3: It was then lowered into the well along with the casing layer to plug the damaged layer;

[0038] S4: Due to the dissolution effect of capsule 1, if the water content of the well where the casing is damaged increases, the tracer content at the wellhead will be detected to determine whether the double sealing has failed.

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0040] The present invention discloses a delayed tracer capsule, comprising a solid tracer 2, strong magnetic particles 3 and a capsule body 1. The solid tracer 2 and the strong magnetic particles 3 are mixed and aggregated in the capsule body 1, and the volume ratio of the solid tracer 2 to the strong magnetic particles 3 is 2:1 to 3:1.

[0041] Preferably, the capsule 1 dissolves in 5-7 days at the target layer temperature, releasing the solid tracer 2 from the capsule 1.

[0042] Preferably, the capsule body 1 is dissolved in the target layer at a temperature of 100~120°C.

[0043] Preferably, the capsule body 1 is dissolved in the target layer at a temperature of 60~70°C.

[0044] A method of using a delayed tracer capsule includes the following steps:

[0045] Solid tracer 2 and strong magnetic particles 3 are mixed at a mass ratio of 2:1 and then aggregated in capsule body 1 to obtain a delayed tracer capsule.

[0046] The obtained multiple delayed tracer capsules were then placed between the two packers 4, so that the capsule body 1 was adsorbed onto the tubing between the two packers 4, and then they were all lowered into the well to plug the casing layer.

[0047] If the water cut of the well where the casing has been plugged increases after the delayed tracer capsule dissolves in the well, the tracer content can be detected at the wellhead to determine whether the double-sealing has failed.

[0048] Example 1

[0049] A method of using a delayed tracer capsule includes the following steps:

[0050] The delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then it is lowered into the well to plug the casing layer.

[0051] Example 2

[0052] A method of using a delayed tracer capsule includes the following steps:

[0053] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing damage layer. In this embodiment, multiple delayed tracer capsules 1 are placed between the two packers 4.

[0054] Example 3

[0055] A method of using a delayed tracer capsule includes the following steps:

[0056] In a preferred embodiment, the delayed tracer capsules are placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then they are lowered into the well together to plug the casing damage layer. In this embodiment, eight delayed tracer capsules 1 are placed between the two packers 4.

[0057] Example 4

[0058] A method of using a delayed tracer capsule includes the following steps:

[0059] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, causing the capsule body 1 to adhere to the tubing between the two packers 4, and then lowered into the well to plug the casing layer. The temperature of the casing layer is 100°C; the capsule body 1 dissolves after 5 days.

[0060] Example 5

[0061] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing string between the two packers 4, and then they are lowered into the well together to plug the casing damage layer. In this embodiment, the two packers 4 are located between the tubing 5 and the casing 6 in the well, and the two packers 4 are located above the casing perforation 7.

[0062] Example 6

[0063] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 119°C.

[0064] Example 7

[0065] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 109°C.

[0066] Example 8

[0067] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the volume ratio of solid tracer 2 to strong magnetic particles 3 is 3:1.

[0068] Example 9

[0069] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the volume ratio of solid tracer 2 to strong magnetic particles 3 is 1.5:1.

[0070] Example 10

[0071] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the volume ratio of solid tracer 2 to strong magnetic particles 3 is 1.8:1.

[0072] Example 11

[0073] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the volume ratio of solid tracer 2 to strong magnetic particles 3 is 1.9:1.

[0074] Example 12

[0075] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then they are lowered into the well to plug the casing damage layer. In this embodiment, if the water cut of the plugged casing oil well increases after the delayed tracer capsule dissolves in the well, the tracer content is detected at the wellhead to determine whether the double-packing has failed.

[0076] Example 13

[0077] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 50°C.

[0078] Example 14

[0079] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 55°C.

[0080] Example 15

[0081] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 58°C.

[0082] Example 16

[0083] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 60°C.

[0084] Example 17

[0085] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 110°C.

[0086] Example 18

[0087] In a preferred embodiment, the delayed tracer capsule is placed between the two packers 4, so that the capsule body 1 is adsorbed onto the tubing between the two packers 4, and then lowered into the well together to plug the casing layer. In this embodiment, the temperature of the casing layer is 110°C, and the number of delayed tracer capsules 1 is eight.

[0088] This invention encapsulates the tracer within a capsule to form a delayed tracer. This allows for the delivery of the tracer to the target formation without contaminating the wellbore, accurately extracting the tracer substrate from the working well. This effectively prevents inaccurate substrate acquisition during conventional tracer injection, which can lead to inaccurate determination of successful plugging. 2. The delayed tracer is placed at the location of the double-sealing casing failure. After a period of time, the capsule dissolves and accumulates between the two seals. If the water cut in the well suddenly increases due to the casing failure, the tracer content can be detected at the wellhead to determine if the double-sealing has failed.

[0089] The present invention uses capsules with slow-dissolving properties. Depending on the temperature of the oil and gas reservoir, the capsules can dissolve in 5-7 days at the target layer temperature, releasing the solid tracer 2 inside the capsules.

[0090] This invention requires the delayed tracer capsule to be accurately placed between the two seals. Therefore, strong magnetic particles 3 are mixed into the solid tracer 2. On the ground, the delayed tracer capsule is strongly adsorbed onto the tubing between the two seals by the strong magnetic particles 3. When the tubing is lowered, it is lowered downhole along with the tubing, thus accurately lowering it to the determined position between the two seals.

[0091] Depending on the temperature of the target layer under different oil well conditions in different regions, the capsule body of the delayed tracer capsule disclosed in this invention can be selectively applied to meet the temperature of the target layer under different oil well conditions and can achieve dissolution at a specific time.

[0092] The delayed tracer capsule disclosed in this invention does not enter the formation and remains between the two packers, primarily for monitoring whether the packer has failed.

[0093] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method of using a delayed tracer capsule, characterized in that, A deferred tracer capsule is used; the deferred tracer capsule includes a solid tracer (2), strong magnetic particles (3) and a capsule body (1), the solid tracer (2) and strong magnetic particles (3) are mixed and aggregated in the capsule body (1), the volume ratio of the solid tracer (2) and strong magnetic particles (3) is 2:1 to 3:1; the capsule body (1) dissolves in 5 to 7 days at the target layer temperature, releasing the solid tracer (2) in the capsule body (1). Includes the following steps: The delayed tracer capsule is placed between the two packers (4), so that the capsule body (1) is adsorbed onto the tubing between the two packers (4), and then they are lowered into the well together to plug the casing layer. If the water cut of the well where the casing is plugged increases after the delayed tracer capsule dissolves in the well, the tracer content can be detected at the wellhead to determine whether the double-sealing has failed. During use, the delayed tracer capsule does not enter the formation and remains between the double packers (4).

2. The method of using a delayed tracer capsule according to claim 1, characterized in that, The temperature of the target layer is 100~120℃.

3. The method of using a delayed tracer capsule according to claim 1, characterized in that, The temperature of the target layer is 60~70℃.

4. The method of using a delayed tracer capsule according to claim 1, characterized in that, The deferred tracer capsules placed between the double packers (4) are multiple.

5. The method of using a delayed tracer capsule according to claim 1, characterized in that, The temperature of the sealing layer is 110℃.

6. The method of using a delayed tracer capsule according to claim 1, characterized in that, The double packer (4) is located between the tubing (5) and the casing (6) in the well.

7. The method of using a delayed tracer capsule according to claim 6, characterized in that, The double packer (4) is located above the casing perforation (7).

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