Bridge plug, classification method and performance detection method

Abstract

The invention belongs to the technical field of oil field exploration tools, and provides a bridge plug, a classification method and a performance detection method.The bridge plug is provided with an inner through hole along the axis, and the minimum aperture of the inner through hole is larger than or equal to 45% of the maximum outer diameter of the bridge plug and smaller than the maximum outer diameter of the bridge plug; the classification categories of the bridge plug comprise a structure type, an anchoring mode, a setting releasing mode, a deblocking mode, technical characteristics, a size, a working temperature, a solubility grade or a drillability grade, effective working time and rated working pressure; and the bridge plug is arranged in the oil casing. According to the bridge plug, the structural characteristics of the large-drift-diameter bridge plug are standardized, and a basis is provided for the structural characteristics of the large-drift-diameter bridge plug; by combining the technical characteristics of the large-drift-diameter bridge plug, the classification model and the detection method of the large-drift-diameter bridge plug are further standardized, the development and the technical progress of the product are promoted, the quality and the performance of the large-drift-diameter bridge plug are effectively improved, the actual working condition requirements are better met and adapted, and technical support is provided for staged fracturing construction.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield exploration tools, and in particular relates to a bridge plug, a classification method and a performance detection method. Background Art

[0002] In the development of unconventional oil and gas resources (shale gas, shale oil, tight oil, etc.) in China, more than 90% of them require reservoir transformation measures to obtain relatively ideal production capacity. "Pumping bridge plug + cluster perforation" and "horizontal well staged fracturing" are the core technical means for unconventional oil and gas reservoir transformation and production increase, and are widely used at home and abroad. As a new type of staged fracturing tool, large-diameter bridge plugs can improve the efficiency of fracturing construction, especially soluble large-diameter bridge plugs, which can quickly return or quickly dissolve to restore the full diameter of the wellbore after fracturing. It has the advantages of high operation timeliness, low comprehensive cost, reduced operation risk, shortened operation cycle, and rapid production. The application of bridge plugs in many national shale gas demonstration areas in China accounts for more than 80%, becoming a key tool for fracturing construction. With the continuous increase in the development of shale gas and shale oil in China, the number of horizontal wells and the number of single well sections have continued to rise, and the market demand and application scale of large-diameter bridge plugs have gradually expanded; large-diameter bridge plugs with the advantages of short length, large diameter, fast dissolution and low cost are becoming more and more widely used, and the total annual usage in China is also increasing, and the product is developing rapidly. The technical upgrading and large-scale promotion of volume fracturing technology and the increasingly complex construction conditions of shale gas fracturing have put forward higher requirements for product performance. However, there are some differences between the structural characteristics, technical parameters, and performance indicators of large-diameter bridge plugs and conventional bridge plugs. Therefore, it is necessary to systematically standardize and unify the structure, technical parameters, and performance indicators of large-diameter bridge plugs, so as to promote product development and technological progress and provide technical support for staged fracturing construction. Summary of the invention

[0003] In order to solve the problems in the background technology, the present invention proposes a bridge plug, a classification method and a performance detection method.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A bridge plug, wherein the bridge plug is provided with an inner through hole along an axis, wherein the minimum aperture of the inner through hole is greater than or equal to 45% of the maximum outer diameter of the bridge plug and is smaller than the maximum outer diameter of the bridge plug; the classification categories of the bridge plug include structural type, anchoring method, setting and releasing method, unsealing method, technical features, size, working temperature, solubility grade or drillability grade, effective working time and rated working pressure; the bridge plug is installed in an oil casing.

[0006] Furthermore, along the axial direction of the oil casing, the bridge plug includes a seal, a cone, a slip and a lower joint which are arranged in sequence;

[0007] The cone is provided with the smallest inner through hole along the axial direction;

[0008] The sealing member abuts against the opening of the inner through hole or cooperates with the smallest inner through hole;

[0009] A tapered hole is provided inside the slip, and the tapered hole is used to cooperate with the cone, and the oil casing is sleeved on the surface of the slip;

[0010] The lower joint abuts against the end of the slip away from the seal.

[0011] Furthermore, a sealing ring is installed on the conical surface of the cone, and when the slip is matched with the cone through the conical hole, the sealing ring abuts against the end of the slip.

[0012] Furthermore, along the axial direction of the slip, a hoop and a plurality of anchoring teeth are sequentially arranged on the surface of the slip.

[0013] Further, the sealing member is a sealing ball or a sealing plug;

[0014] When the sealing ball is matched with the cone, the sealing ball abuts against the opening of the stepped hole of the cone; when the sealing plug is matched with the cone, the sealing plug is matched with the stepped hole of the cone.

[0015] A classification method comprises the following steps:

[0016] Bridge plugs are classified by classification categories, including structural type, anchoring method, setting and releasing method, release method, technical characteristics, size, working temperature, solubility grade or drillability grade, effective working time and rated working pressure.

[0017] Further:

[0018] According to the structural type, the bridge plug includes compression type, expansion type, wedging type and combination type;

[0019] According to the anchoring method, the bridge plug includes single slip type, hanging slip type and double slip type;

[0020] According to the setting and releasing method, the bridge plug includes hydraulic setting type, lower pipe setting type, and lower tool setting type;

[0021] According to the unsealing method, the bridge plug includes lifting and releasing pipe string unsealing, drilling and milling unsealing, pressure regulation unsealing, dissolving unsealing and non-unsealing;

[0022] According to the technical features, the bridge plug includes insoluble, partially soluble and fully soluble;

[0023] When classifying by size, record the maximum outer diameter and minimum inner diameter of the bridge plug;

[0024] When classified according to the working temperature, the bridge plugs are classified into different working temperature ranges;

[0025] When classified according to rated working pressure, bridge plugs are classified into different rated working pressures;

[0026] When classified according to solubility levels, bridge plugs are classified into different dissolution times;

[0027] When classifying according to drillability level, bridge plugs are classified into different drilling and grinding times;

[0028] When classified by effective working time, the effective working time of the bridge plug for continuous pressure stabilization shall be recorded.

[0029] A performance testing method, applied to the above-mentioned bridge plug, comprises the following steps:

[0030] Check the appearance of the bridge plug and measure the size of the bridge plug;

[0031] Detect the setting and releasing performance of the bridge plug;

[0032] After the setting and releasing performance of the bridge plug is qualified, the normal temperature pressure bearing performance of the bridge plug is tested;

[0033] After the normal temperature pressure bearing performance of the bridge plug is qualified, the temperature resistance and pressure bearing performance of the bridge plug is tested;

[0034] Detect the stable sealing performance of the bridge plug;

[0035] After the stable sealing performance test of the bridge plug is qualified, the soluble performance test or the drillable performance test is selected according to the technical characteristics of the bridge plug.

[0036] Further, the appearance of the bridge plug is inspected and the size of the bridge plug is measured, including the following steps:

[0037] Check whether the bridge plug is deformed, whether there are cracks and scratches on the surface, and whether the threads of the bridge plug are damaged;

[0038] Measure the maximum outer diameter, minimum inner diameter, length and total weight of the bridge plug.

[0039] Further, testing the setting and releasing performance of the bridge plug includes the following steps:

[0040] The bridge plug is set and released. The bridge plug is set in the oil casing. If the setting tool is separated from the bridge plug and there is no tool jam or the bridge plug is half-set or not set, the release is successful and the setting and releasing performance of the bridge plug is qualified.

[0041] Record the setting and releasing force, derive the relationship curve between the setting and releasing force and time / displacement, and measure and calculate the actual setting stroke of the bridge plug;

[0042] Check the anchoring status of the bridge plug in the casing after it is set and released, the fit between the bridge plug and the inner wall of the casing, and verify and confirm the initial sealing condition.

[0043] Further, testing the normal temperature pressure bearing performance of the bridge plug includes the following steps:

[0044] Infuse the standard solution into the cavities at both ends of the bridge plug, exhaust all the air in the cavity at one end, increase the pressure at the upper end of the bridge plug to the rated working pressure, stabilize the pressure for 15 minutes after the pressure stabilizes, and record the pressure drop. The upper end is the end of the bridge plug corresponding to the seal;

[0045] Determine whether the pressure drop is less than or equal to 5% of the rated working pressure. If the pressure drop is less than or equal to 5% of the rated working pressure, the normal temperature pressure bearing performance of the bridge plug is determined to be qualified, and the "pressure-time" numerical curve is saved after the pressure is released;

[0046] If the pressure drop is greater than 5% of the rated working pressure, retesting is performed at most twice. If the pressure drop of all retests is greater than 5% of the rated working pressure, the normal temperature pressure bearing performance of the bridge plug is judged to be unqualified, and subsequent detection steps are stopped.

[0047] Further, testing the temperature and pressure resistance of the bridge plug includes the following steps:

[0048] Heat the bridge plug and casing to the working temperature and keep them warm;

[0049] The upper end of the bridge plug is pressurized to the rated working pressure, and the pressure change is observed. After the pressure stabilizes, the pressure is stabilized for 15 minutes, and the pressure drop is recorded. The pressure is released, and the numerical curve of "temperature-pressure-time" is saved; the upper end is the end of the bridge plug corresponding to the seal;

[0050] Determine whether the pressure drop is less than or equal to 5% of the rated working pressure. If so, the temperature and pressure resistance of the bridge plug is qualified; otherwise, the temperature and pressure resistance of the bridge plug is unqualified.

[0051] Further, testing the stable sealing performance of the bridge plug includes the following steps:

[0052] Keep the bridge plug at working temperature and rated working pressure and maintain constant pressure;

[0053] When a single pressure drop is no more than 5% of the rated working pressure and the total pressure drop is no more than 20% of the rated working pressure, the stable sealing performance of the bridge plug is determined to be qualified and recorded as the effective working time. Otherwise, the stable sealing performance of the bridge plug is unqualified; the effective working time is determined according to the corresponding different time levels and is selected from 8 to 48 hours;

[0054] The pressure relief saves the numerical curve of "temperature-pressure-time".

[0055] Further, the solubility test is performed, comprising the following steps:

[0056] Weigh the oil casing with the bridge plug set and record the initial weight;

[0057] Immerse the oil casing with the bridge plug in the standard solution and heat it to the working temperature for insulation;

[0058] Check and replenish the standard solution every 2h to 8h to ensure that the volume of the standard solution remains unchanged. Weigh and record every 24h. Replace the standard solution every 24h to 72h and record the time of bridge plug dissolution.

[0059] After the dissolution is completed, the residue of the bridge plug is filtered out, the mass of the residue is weighed, and the maximum length of the largest monomer of the residue in any direction is measured to determine the solubility level of the bridge plug.

[0060] Further, the drillability test is performed, including the following steps:

[0061] Drilling and grinding bridge plugs installed in oil casing;

[0062] The time from the start of drilling to the complete release of the bridge plug from the oil casing is recorded to determine the drillability level of the bridge plug.

[0063] Furthermore, the method also includes a step of testing the quick dissolution performance of the bridge plug:

[0064] Determine the technical characteristics of the bridge plug;

[0065] If the technical feature of the bridge plug is that it is partially soluble or fully soluble, then between the testing of the bridge plug's setting and releasing performance and the normal temperature pressure bearing performance or after the testing of the bridge plug's temperature and pressure resistance performance, the oil casing with the bridge plug installed shall be immersed in an acid solution or a solution with a potassium chloride mass of not less than 10% to 20%, and the time when the bridge plug is unsealed or falls off from the oil casing shall be recorded.

[0066] Beneficial effects of the present invention:

[0067] 1. The bridge plug of the present invention standardizes the structural characteristics of the large-diameter bridge plug, thereby providing a basis for the structural characteristics of the large-diameter bridge plug;

[0068] 2. The classification method of the present invention is conducive to standardizing and unifying the classification forms of large-diameter bridge plugs;

[0069] 3. The performance testing method of the present invention is conducive to providing a unified and standardized testing basis for the performance testing of large-diameter bridge plugs;

[0070] 4. The present invention combines the technical characteristics of large-diameter bridge plugs to further standardize the classification and model representation methods, performance indicators, technical requirements and testing methods of the products, promote product development and technological progress, effectively improve the quality and performance of large-diameter bridge plugs, better meet and adapt to actual working conditions, and provide technical support for staged fracturing construction.

[0071] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0073] Figure 1a Outputting a schematic structural diagram of the bridge plug of the present invention;

[0074] Figure 1b A schematic diagram of the bridge plug with a sealing ball of the present invention when it is set is shown;

[0075] Figure 1c A schematic diagram of the bridge plug with a sealing plug of the present invention when it is set is shown;

[0076] Figure 2 A flow chart showing the bridge plug classification representation method of the present invention is shown;

[0077] Figure 3 An example diagram showing a method for representing the model of the bridge plug of the present invention is shown;

[0078] Figure 4 A flow chart showing the classification method of the present invention is shown;

[0079] Figure 5 A flow chart of a method for detecting the performance of a bridge plug of the present invention is shown.

[0080] In the figure: 1. sealing ball; 2. cone; 3. sealing ring; 4. hoop; 5. slip; 501, tapered hole; 6. anchoring tooth; 7. lower joint; 8. oil casing; 9. sealing plug. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] like Figure 1a The figure shows a bridge plug, which includes a seal, a cone 2, a slip 5 and a lower joint 7 arranged in sequence along the axial direction. The cone 2 is provided with a through inner through hole (step hole) of a large diameter in the axial direction, and the minimum aperture of the inner through hole of the large diameter (the minimum inner diameter of the bridge plug) is not less than 45% of the maximum outer diameter of the bridge plug, and is smaller than the maximum outer diameter of the bridge plug. When the bridge plug is set, the seal abuts against the opening of the step hole or cooperates with the step hole. In addition, a tapered hole 501 is provided inside the slip 5, and the tapered hole 501 can cooperate with the cone 2 when setting, and the oil casing 8 is sleeved on the surface of the slip 5 when setting. The lower joint 7 abuts against the end of the slip 5 away from the seal.

[0083] It should be noted that Figure 1a The bridge plug is a large-diameter bridge plug. The characteristics of this type of bridge plug are: it is used to seal the space inside the oil casing 8 during staged fracturing and has a large inner diameter. Usually, the minimum inner diameter of the bridge plug should not be less than 45% of the maximum outer diameter of the bridge plug and should be smaller than the maximum outer diameter of the bridge plug.

[0084] It should be further explained that the slip 5 is composed of a plurality of petal structures with certain arc surfaces, and a plurality of petal structures are combined to form a tapered hole 501 .

[0085] In addition, a sealing ring 3 is installed on the conical surface of the cone 2. When the slip 5 is matched with the cone 2 through the conical hole 501, the sealing ring 3 will abut against the end of the slip 5. A hoop 4 and a plurality of anchor teeth 6 are sequentially arranged on the surface of the slip 5 along the axial direction of the slip 5, wherein the hoop 4 can improve the sealing performance of the oil casing 8 after the slip 5 is matched, and the anchor teeth 6 can anchor the slip 5 inside the oil casing 8.

[0086] Combination Figure 1a , Figure 1b and Figure 1c In some optional embodiments, the sealing member can be a sealing ball 1 or a sealing plug 9. When the sealing ball 1 is matched with the cone 2, the sealing ball 1 abuts against the opening of the step hole of the cone 2, and a chamfer that matches the sealing ball 1 can be provided at the opening of the step hole. If the sealing plug 9 is matched with the cone 2, the sealing plug 9 can be adapted to the step hole of the cone 2, and the two can match each other. In addition Figure 1b and Figure 1cThis is the state after the seal is set, and the lower joint falls off.

[0087] It should be noted that, usually, a large-diameter bridge plug should have at least two structural designs to prevent premature setting, anti-stuck, anti-drop, improve pumping efficiency, set flow channel, spare ball seat, auxiliary dissolution, etc. Usually, a thread or pin is provided at the inner hole of the lower joint 7. The sealing tool works and provides axial drive to drive the cone 2 to move axially. The sealing ring 3 and the slip assembly expand along the conical surface until they are close to the inner wall of the casing. During the continuous loading process, the anchoring teeth 6 bite into the inner wall of the casing to achieve setting, and then the axial force shears the thread or pin of the lower joint 7, and the sealing tool is separated from the bridge plug. The sealing ring 3 mainly seals the annulus between the cone 2 and the inner wall of the casing. After setting, the seal is put into the cone hole at the upper end of the cone 2 to block the inner hole channel of the bridge plug. The recommended sizes of large-diameter bridge plugs corresponding to commonly used oil casing 8 are shown in Table 1.

[0088] Table 1

[0089]

[0090] A classification method applied to Figure 1a-Figure 1c The bridge plug in the Figure 2 It can be seen that it includes the following steps:

[0091] Bridge plugs are classified by structural type, anchoring method, setting and releasing method, unsealing method, technical characteristics, size (maximum outer diameter × minimum inner diameter), working temperature, solubility grade or drillability grade, effective working time and rated working pressure, and finally the classification type of bridge plugs is determined.

[0092] Specifically, the structural type of large-diameter bridge plugs is classified by the sealing structure of the bridge plug, which is mainly divided into compression type, expansion type, wedge type and combination type; the classification code is represented by the capital letter of the first Chinese character of the sealing structure, that is, the classification code of the compression type is Y, the classification code of the expansion type is K, the classification code of the wedge type is X, and the classification code of the combination type is Z.

[0093] According to the classification of anchoring method, they are single slip type, hanging card type and double slip type. The codes are represented by numbers, that is, the classification code of single slip type is 2, the classification code of hanging card type is 3, and the classification code of double slip type is 4.

[0094] The classification of setting and releasing modes is as follows: hydraulic setting, tubing string setting, and tool setting. The codes are represented by numbers, i.e., the classification code for hydraulic setting is 2, the classification code for tubing string setting is 3, and the classification code for tool setting is 4.

[0095] The unsealing methods are classified into: pipe lifting and releasing unsealing, drilling and milling unsealing, pressure regulation unsealing, dissolving unsealing, and non-unsealing. The classification codes are represented by the numbers 1, 2, 3, 4, and 5 respectively.

[0096] The classification of technical characteristics is: insoluble, partially soluble, and fully soluble. The codes are represented by capital letters, that is, the classification code for insoluble is BR, the classification code for partially soluble is FR, and the classification code for fully soluble is QR. See Table 1 for details.

[0097] Table 2: Technical characteristics and classification codes

[0098] Technical feature name Insoluble Partially soluble Fully soluble Technical feature code BR FR QR

[0099] When classifying by size, record the maximum outer diameter and minimum inner diameter of the bridge plug. The maximum outer diameter and minimum inner diameter are the actual dimensions of the large-diameter bridge plug, expressed in millimeters.

[0100] When classified according to the working temperature, the bridge plug is classified into different working temperature ranges. The working temperature is the highest temperature that the bridge plug can withstand when it is stably sealed. The working temperature ranges from 20℃ to 200℃, and is divided into 8 temperature levels. The classification codes are represented by capital letters; that is, 20℃ to 40℃ is coded as C, 40℃ to 60℃ is coded as D, 60℃ to 80℃ is coded as L, 80℃ to 100℃ is coded as M, 100℃ to 125℃ is coded as G, 125℃ to 150℃ is coded as H, 150℃ to 175℃ is coded as S, and 175℃ to 200℃ is coded as E. See Table 3 for details.

[0101] Table 3: Operating temperature grade code

[0102]

[0103] When classified according to rated working pressure, the bridge plugs are classified into different rated working pressures. The rated working pressure is the pressure difference that the upper end of the bridge plug can stably withstand when the bridge plug is isolated in the oil casing 8. It is divided into 5 pressure levels within the range of 35MPa to 150MPa, namely: 35MPa, 50MPa, 70MPa, 105MPa, and 150MPa.

[0104] Stable sealing performance refers to the different times corresponding to the effective working time level of the bridge plug under certain working temperature and rated working pressure conditions. During the continuous pressure stabilization process within the effective working time, the single pressure drop is not greater than 5% of the rated working pressure, and the total pressure drop is not greater than 20% of the rated working pressure. The effective working time is the time when the bridge plug withstands the rated working pressure and continues to maintain the sealing pressure under the pre-set working temperature and other working conditions. It can be divided into 4 levels, namely: greater than or equal to 8 hours, greater than or equal to 16 hours, greater than or equal to 24 hours, and greater than or equal to 48 hours, and the codes are represented by the numbers 1, 2, 3, and 4 respectively.

[0105] When classified according to the solubility level, the bridge plug is classified into different dissolution times. The solubility level is characterized by the dissolution time, that is, the total time taken for the bridge plug to fully dissolve into a residue of a certain size under certain conditions. It can be divided into 4 levels, namely: less than or equal to 4 days, less than or equal to 8 days, less than or equal to 12 days, and less than or equal to 16 days, and the codes are represented by the numbers 1, 2, 3, and 4 respectively.

[0106] When classified according to drillability level, bridge plugs are classified into different drilling and grinding times. The drillability level is characterized by the drilling and grinding time, that is, under certain conditions (usually continuous drilling and grinding under the conditions of drilling pressure of 20kN to 30kN and rotation speed of 30r / min to 50r / min), the time to grind the bridge plug body into pieces and unseal it from the oil casing 8 can be divided into 4 levels, namely: less than or equal to 30 minutes, less than or equal to 60 minutes, less than or equal to 90 minutes, less than or equal to 120 minutes, and the codes are represented by the numbers 1, 2, 3, and 4 respectively.

[0107] like Figure 3 As shown, after classification in the above way, it can correspond to Figure 3 The position in the middle gives the classification number of the bridge plug. For example: Y432BR-106×55-G32-105 large-diameter bridge plug: indicates compression seal, double slip anchoring, tool setting, drilling and milling release, insoluble, maximum outer diameter 106mm, minimum inner diameter 55mm, working temperature range 100℃~125℃, effective working time greater than or equal to 24h, drilling and milling time less than or equal to 60min, rated working pressure 105MPa.

[0108] For example: K235QR-98×45-M21-70 large-diameter bridge plug: It is indicated as expansion seal, single slip anchor, lower tool sealing, dissolution and unsealing, fully soluble, maximum outer diameter 98mm, minimum inner diameter 45mm, working temperature range 80℃~100℃, effective sealing time greater than or equal to 16h, full dissolution time in standard solution less than or equal to 4d, and rated working pressure 70MPa.

[0109] A performance testing method, applied to Figure 1a-Figure 1c The bridge plug, such as Figure 4 It is shown that it includes the following steps:

[0110] S1: Check the appearance of the bridge plug and measure the size of the bridge plug.

[0111] S2: Check the setting and releasing performance of the bridge plug.

[0112] S3: After the setting and releasing performance of the bridge plug is qualified, the pressure bearing performance of the bridge plug at room temperature is tested.

[0113] S4: After the normal temperature pressure bearing performance of the bridge plug is qualified, the temperature resistance and pressure bearing performance of the bridge plug is tested.

[0114] S5: Check the stable sealing performance of the bridge plug.

[0115] S6: After the stable sealing performance test of the bridge plug is qualified, the soluble performance test or the drillable performance test is selected according to the technical characteristics of the bridge plug.

[0116] In addition, combined Figure 5 It can be seen that S1-S5 also include the step of testing the quick dissolution performance of the bridge plug:

[0117] First, the technical characteristics of the bridge plug are determined; if the technical characteristics of the bridge plug are partially soluble or fully soluble, then between the testing of the setting and releasing performance and the normal temperature pressure bearing performance of the bridge plug or after the testing of the temperature and pressure resistance of the bridge plug, the oil casing 8 installed with the bridge plug is immersed in an acid solution, and the time when the bridge plug is unsealed or falls off from the oil casing 8 is recorded, wherein unsealing refers to the seal losing its sealing ability and the slip 5 losing its anchoring ability, and falling off refers to the entire bridge plug being separated from the inner wall of the casing.

[0118] It should be noted that, for the rapid dissolution performance test of the large-diameter bridge plug with technical characteristics of partial dissolution and full dissolution, usually after the bridge plug is sealed in the oil pipe and before the normal temperature pressure bearing performance test is carried out, certain rapid dissolution treatment measures are taken, such as high-concentration chloride solution, acid solution, etc., so that the bridge plug can be quickly unsealed or fallen off from the oil casing 8. If necessary, the large-diameter bridge plug can also be selected to pass various performance index tests, and the performance test results can be recorded in the large-diameter bridge plug type inspection record table (as shown in Table 4), and based on the actual test data and judgment results.

[0119] Table 4: Large-diameter bridge plug inspection record

[0120]

[0121] The process of S1-S6 is further explained below.

[0122] Exemplarily, S1 includes the following steps:

[0123] S101: Check whether the bridge plug is deformed, whether there are cracks and scars on the surface, and whether the thread of the bridge plug is damaged; S102: Measure the maximum outer diameter, minimum inner diameter, length and total weight of the bridge plug.

[0124] It should be noted that S101 mainly ensures that the parts of the bridge plug are free of deformation, cracks and scars, and the threads of the slip 5 and the lower joint 7 are not damaged. In addition, when measuring the maximum outer diameter, minimum inner diameter and length of the bridge plug, the size is accurate to 0.1mm, and the bridge plug is weighed with a weighing instrument with a suitable range, and the weight is accurate to 0.1g.

[0125] Exemplarily, S2 includes the following steps:

[0126] S201: Setting the bridge plug in the oil casing 8, recording the setting release force, deriving a relationship curve between the setting release force and time / displacement, and measuring and calculating the actual setting stroke of the bridge plug;

[0127] S202: Check the anchoring state of the slip 5 in the oil casing 8 after the bridge plug is set and released, and the fit between the sealing ring 3 and the inner wall of the oil casing 8, and verify and confirm the initial sealing condition.

[0128] It should be noted that before performing S201, it is necessary to check the bridge plug, test oil casing 8 and the adapter, and related accessories of the sealing tool to ensure that there is no abnormality in the operation of the test sealing tool. Connect the tool according to the design requirements to ensure that the connection between the bridge plug and the adapter and the sealing tool is tight. After that, the electric or hydraulic device can be started to drive the sealing tool to seal the bridge plug in the test oil casing 8 and execute S201.

[0129] Exemplarily, S3 includes the following steps:

[0130] S301: Match the sealing member with the cone 2; for example, place the sealing ball 1 into the ball seat or rotate the sealing plug 9 into the stepped hole of the bridge plug.

[0131] S302: Pour standard solution into the cavities at both ends of the bridge plug, exhaust all the air in the upper cavity, pressurize the upper end of the bridge plug to the rated working pressure, observe the pressure change, stabilize the pressure after the pressure stabilizes (the stabilization time can be selected as 15 minutes), and record the pressure drop. The upper end is the end of the bridge plug corresponding to the seal.

[0132] S303: Determine whether the pressure drop is less than or equal to 5% of the rated working pressure. If the pressure drop is less than or equal to 5% of the rated working pressure, the normal temperature pressure bearing performance of the bridge plug is determined to be qualified, and the "pressure-time" numerical curve is saved after the pressure is released.

[0133] S304: If the pressure drop is greater than 5% of the rated working pressure, retest at most twice. If all retested pressure drops are greater than 5% of the rated working pressure, the normal temperature pressure bearing performance of the bridge plug is determined to be unqualified, and subsequent detection steps are stopped.

[0134] It should be noted that in S304, when the pressure drop value is greater than 5% and less than or equal to 10%, the upper end of the bridge plug can be pressurized to the rated working pressure, and a secondary normal temperature pressure bearing performance test can be performed. The pressure is maintained for 15 minutes, and the pressure drop is observed and recorded. If the pressure drop value is not greater than 5% of the rated working pressure, the next test link can be performed. The normal temperature pressure bearing performance test can be performed for a maximum of three pressure drop tests with a pressure of 15 minutes. If the requirements are not met for three times, the test is terminated by direct pressure relief, and it is judged as unqualified, and the next link of the test is not performed.

[0135] Exemplarily, S4 includes the following steps:

[0136] S401: Put the bridge plug and the oil casing 8 that have completed the normal temperature pressure bearing performance test into a heating device as a whole, heat it to the working temperature and keep it warm.

[0137] S402: Increase the pressure at the upper end of the bridge plug to the required rated working pressure, observe the pressure change, and after the pressure stabilizes, stabilize the pressure for 15 minutes, record the pressure drop, release the pressure, and save the "temperature-pressure-time" numerical curve; the upper end is the end of the bridge plug corresponding to the seal.

[0138] S403: Determine whether the pressure drop is less than or equal to 5% of the rated working pressure. If so, the heat and pressure resistance of the bridge plug is qualified; otherwise, the heat and pressure resistance of the bridge plug is unqualified.

[0139] It should be noted that in order to fully test the temperature resistance of the bridge plug, the highest temperature is usually selected for temperature and pressure resistance testing based on the working temperature index range of the bridge plug. For example, for a bridge plug with an working temperature grade of 80℃~100℃, 100℃ is selected as the temperature and pressure resistance condition.

[0140] It should be further explained that in S403, if the temperature and pressure resistance of the bridge plug is unqualified, the actual pressure drop value can be recorded for 15 minutes. However, if this indicator is judged as unqualified, stable sealing performance, dissolution / drilling removal tests, etc. can still be carried out.

[0141] Exemplarily, S5 includes the following steps:

[0142] The bridge plug is kept at the working temperature and rated working pressure and the pressure is continuously stabilized. During the continuous pressure stabilization process, the upper end of the bridge plug is not pressurized. When a single pressure drop is not greater than 5% of the rated working pressure, and the total pressure drop is not greater than 20% of the rated working pressure, the stable sealing performance of the bridge plug is determined to be qualified and recorded as the effective working time. Otherwise, the stable sealing performance of the bridge plug is unqualified. Subsequently, the pressure is released to save the numerical curve of "temperature-pressure-time". The upper end is one end of the bridge plug corresponding to the seal.

[0143] It should be noted that the effective working time is determined according to the corresponding different time levels and is selected from 8 to 48 hours.

[0144] Exemplarily, if S6 performs solubility testing, it includes the following steps:

[0145] S601a: Weigh the oil casing 8 with the bridge plug and record the initial weight. S602a: Immerse the oil casing 8 with the bridge plug in the standard solution and heat it to the working temperature for insulation. S603a: Keep immersing, check and replenish the standard solution every 2 to 8 hours to ensure that the volume of the standard solution remains unchanged, weigh and record every 24 hours, replace the standard solution every 24 to 72 hours, and record the dissolution time of the bridge plug; S604a: After the dissolution is completed, use a 4mm×4mm filter to filter out the residue of the bridge plug, weigh the mass of the residue and measure the maximum length of the largest monomer of the residue in any direction, and then determine the solubility level of the bridge plug.

[0146] It should be noted that in S601a, the oil casing 8 with the bridge plug is weighed and the initial weight is recorded, and the whole is placed in a dissolution test device, and a standard solution (acidic solution or a solution with a potassium chloride mass of not less than 10% to 20%) is configured in the dissolution test device to ensure that the standard solution can fully immerse the oil casing 8. In addition, when performing the solubility test, in order to fully test the solubility of the bridge plug, the lowest temperature is usually selected for the solubility test according to the working temperature index range of the bridge plug. For example, for a bridge plug with a working temperature level of 80°C to 100°C, 80°C is selected as the dissolution test condition.

[0147] Exemplarily, the drillability test in S6 includes the following steps:

[0148] S601b: Install the oil casing 8 with the bridge plug set on the drilling and milling test device. S602b: Drill out the set bridge plug according to the corresponding drilling and milling parameters, and record the time from the start of drilling and milling to the complete release of the bridge plug from the oil casing 8, so as to determine the drillability level of the bridge plug.

[0149] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bridge plug, characterized in that: The bridge plug is provided with an inner through hole along the axis, and the minimum aperture of the inner through hole is greater than or equal to 45% of the maximum outer diameter of the bridge plug, and smaller than the maximum outer diameter of the bridge plug; The classification categories of the bridge plug include structural type, anchoring method, setting and releasing method, unsealing method, technical characteristics, size, working temperature, solubility level or drillability level, effective working time and rated working pressure; The bridge plug is installed in the oil casing (8).

2. A bridge plug according to claim 1, characterized in that: Along the axial direction of the oil casing (8), the bridge plug comprises a sealing member, a cone (2), a slip (5) and a lower joint (7) which are arranged in sequence; The cone (2) is provided with the smallest inner through hole along the axial direction; The sealing member abuts against the opening of the inner through hole or cooperates with the smallest inner through hole; The slip (5) has a conical hole (501) formed inside, the conical hole (501) being used to cooperate with the cone (2), and the oil casing (8) is sleeved on the surface of the slip (5); The lower joint (7) abuts against the end of the slip (5) away from the sealing member.

3. A bridge plug according to claim 2, characterized in that: A sealing ring (3) is installed on the conical surface of the cone (2); when the slip (5) is matched with the cone (2) through the conical hole (501), the sealing ring (3) abuts against the end of the slip (5).

4. A bridge plug according to claim 3, characterized in that: Along the axial direction of the slip (5), a hoop (4) and a plurality of anchoring teeth (6) are sequentially arranged on the surface of the slip (5).

5. A bridge plug according to claim 2, characterized in that: The sealing element is a sealing ball (1) or a sealing plug (9); When the sealing ball (1) is matched with the cone (2), the sealing ball (1) abuts against the opening of the stepped hole of the cone (2); when the sealing plug (9) is matched with the cone (2), the sealing plug is matched with the stepped hole of the cone (2).

6. A classification method, characterized in that: The following steps are involved: Bridge plugs are classified by classification categories, including structural type, anchoring method, setting and releasing method, release method, technical characteristics, size, working temperature, solubility grade or drillability grade, effective working time and rated working pressure.

7. A classification method according to claim 6, characterized in that: According to the structural type, the bridge plug includes compression type, expansion type, wedging type and combination type; According to the anchoring method, the bridge plug includes single slip type, hanging slip type and double slip type; According to the setting and releasing method, the bridge plug includes hydraulic setting type, lower pipe setting type, and lower tool setting type; According to the unsealing method, the bridge plug includes lifting and releasing pipe string unsealing, drilling and milling unsealing, pressure regulation unsealing, dissolving unsealing and non-unsealing; According to the technical features, the bridge plug includes insoluble, partially soluble and fully soluble; When classifying by size, record the maximum outer diameter and minimum inner diameter of the bridge plug; When classified according to the operating temperature, the bridge plugs are classified into different operating temperature ranges; When classified according to rated working pressure, bridge plugs are classified into different rated working pressures; When classified according to solubility levels, bridge plugs are classified into different dissolution times; When classifying according to drillability level, bridge plugs are classified into different drilling and grinding times; When classified by effective working time, the effective working time of the bridge plug for continuous pressure stabilization shall be recorded.

8. A performance testing method, applied to the bridge plug according to any one of claims 1 to 5, characterized in that: The following steps are involved: Check the appearance of the bridge plug and measure the size of the bridge plug; Detect the setting and releasing performance of the bridge plug; After the setting and releasing performance of the bridge plug is qualified, the normal temperature pressure bearing performance of the bridge plug is tested; After the normal temperature pressure bearing performance of the bridge plug is qualified, the temperature resistance and pressure bearing performance of the bridge plug is tested; Detect the stable sealing performance of the bridge plug; After the stable sealing performance test of the bridge plug is qualified, the soluble performance test or the drillable performance test is selected according to the technical characteristics of the bridge plug.

9. A performance detection method according to claim 8, characterized in that: Check the appearance of the bridge plug and measure the size of the bridge plug, including the following steps: Check whether the bridge plug is deformed, whether there are cracks and scratches on the surface, and whether the threads of the bridge plug are damaged; Measure the maximum outer diameter, minimum inner diameter, length and total weight of the bridge plug.

10. A performance detection method according to claim 8, characterized in that: Testing the setting and releasing performance of the bridge plug includes the following steps: The bridge plug is set and released, and the bridge plug is set in the oil casing (8). If the setting tool is separated from the bridge plug and there is no tool jam or the bridge plug is half-set or not set, the release is successful and the setting and releasing performance of the bridge plug is qualified; Record the setting and releasing force, derive the relationship curve between the setting and releasing force and time / displacement, and measure and calculate the actual setting stroke of the bridge plug; Check the anchoring state of the bridge plug in the oil casing (8) after the bridge plug is set and released, and the fit between the bridge plug and the inner wall of the oil casing (8), and verify and confirm the initial sealing condition.

11. A performance detection method according to claim 8, characterized in that: Testing the normal temperature pressure bearing performance of the bridge plug includes the following steps: Infuse the standard solution into the cavities at both ends of the bridge plug, exhaust all the air in the cavity at one end, increase the pressure at the upper end of the bridge plug to the rated working pressure, stabilize the pressure for 15 minutes after the pressure stabilizes, and record the pressure drop. The upper end is the end of the bridge plug corresponding to the seal; Determine whether the pressure drop is less than or equal to 5% of the rated working pressure. If the pressure drop is less than or equal to 5% of the rated working pressure, the normal temperature pressure bearing performance of the bridge plug is determined to be qualified, and the "pressure-time" numerical curve is saved after pressure relief; If the pressure drop is greater than 5% of the rated working pressure, retesting is performed at most twice. If the pressure drop of all retests is greater than 5% of the rated working pressure, the normal temperature pressure bearing performance of the bridge plug is judged to be unqualified, and subsequent detection steps are stopped.

12. A performance detection method according to claim 8, characterized in that: Testing the temperature and pressure resistance of the bridge plug includes the following steps: Heating the bridge plug and the oil casing (8) to the working temperature and keeping them warm; The upper end of the bridge plug is pressurized to the rated working pressure, and the pressure change is observed. After the pressure stabilizes, the pressure is stabilized for 15 minutes, and the pressure drop is recorded. The pressure is released, and the numerical curve of "temperature-pressure-time" is saved; the upper end is the end of the bridge plug corresponding to the seal; Determine whether the pressure drop is less than or equal to 5% of the rated working pressure. If so, the temperature and pressure resistance of the bridge plug is qualified; otherwise, the temperature and pressure resistance of the bridge plug is unqualified.

13. A performance detection method according to claim 8, characterized in that: Testing the stable sealing performance of the bridge plug includes the following steps: Keep the bridge plug at working temperature and rated working pressure and maintain constant pressure; When a single pressure drop is no more than 5% of the rated working pressure and the total pressure drop is no more than 20% of the rated working pressure, the stable sealing performance of the bridge plug is determined to be qualified and recorded as the effective working time. Otherwise, the stable sealing performance of the bridge plug is unqualified; the effective working time is determined according to the corresponding different time levels and is selected from 8 to 48 hours; The pressure relief saves the "temperature-pressure-time" numerical curve.

14. A performance detection method according to claim 8, characterized in that: The solubility test includes the following steps: Weighing the oil casing (8) with the bridge plug set and recording the initial weight; The oil casing (8) with the bridge plug set is immersed in the standard solution, and the temperature is raised to the working temperature and kept warm; Check and replenish the standard solution every 2h to 8h to ensure that the volume of the standard solution remains unchanged. Weigh and record every 24h. Replace the standard solution every 24h to 72h and record the time of bridge plug dissolution. After the dissolution is completed, the residue of the bridge plug is filtered out, the mass of the residue is weighed, and the maximum length of the largest monomer of the residue in any direction is measured to determine the solubility level of the bridge plug.

15. A performance detection method according to claim 8, characterized in that: The drillability test includes the following steps: Drilling and grinding a bridge plug installed in the oil casing (8); The time from the start of drilling to the complete release of the bridge plug from the oil casing (8) is recorded to determine the drillability level of the bridge plug.

16. A performance detection method according to any one of claims 8 to 15, characterized in that: It also includes the quick dissolution performance test steps of the bridge plug: Determine the technical characteristics of the bridge plug; If the technical feature of the bridge plug is that it is partially soluble or fully soluble, between testing the setting and releasing performance and the pressure bearing performance at room temperature of the bridge plug or after testing the temperature and pressure bearing performance of the bridge plug, the oil casing (8) installed with the bridge plug is immersed in an acid solution or a solution containing potassium chloride of not less than 10% to 20% by mass, and the time when the bridge plug is unsealed or falls off from the oil casing (8) is recorded.

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