A method for monitoring oil and gas well fracturing production profile using trace tracers

Abstract

The present invention provides a method for monitoring the production profile of oil and gas well fracturing using trace tracers. The method includes: determining the type and model of the trace tracer used in each fracturing section of the target well; determining the designed dosage, pumping timing and pumping speed of the trace tracer used in each fracturing section of the target well; wherein the pumping timing of the trace tracer is: injecting the water phase tracer in the pre-fluid stage and the sand-carrying fluid stage; when the sand-carrying fluid stage does not perform fracture extension, injecting the oil phase tracer and the gas phase tracer in the pre-fluid stage; when the sand-carrying fluid stage performs fracture extension, injecting the oil phase tracer and the gas phase tracer in the sand-carrying fluid stage; completing the injection operation of the trace tracer during the fracturing construction of each fracturing section of the target well; sampling the target well during the post-fracturing flowback and production process of the target well, thereby determining the model and content of the trace tracer contained in each sample, and then determining the production profile of each fracturing section of the target well in combination with the production data during the post-fracturing flowback and production process.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas well fracturing and production increase, and in particular relates to a method for monitoring an oil and gas well fracturing output profile by using a trace tracer. Background Art

[0002] During oil and gas field development, a large number of oil and gas wells require fracturing to be put into production. Multi-stage, multi-cluster, large-scale volume fracturing technology has gradually become the mainstream technology for fracturing development and production in oil and gas fields. Currently, multi-stage, multi-cluster, large-scale volume fracturing technology has many problems, such as the large construction scale, the large number of vehicle units involved, and high construction costs. Furthermore, the dynamic patterns of post-fracturing drainage and production are unclear, and there is insufficient understanding of the reservoir and targeted evaluation of process parameters.

[0003] To address the issue of unclear post-fracture drainage and production dynamics, tracers are often used to monitor the production profiles of various stages of oil and gas well fracturing. However, effective monitoring is often not possible using tracers, especially in tight oil and gas and shale oil and gas reservoirs.

[0004] Therefore, there is still a need to optimize the method of using tracers to monitor the production profile of oil and gas well fracturing, so as to better understand the production profile of oil and gas wells with the help of monitoring methods during post-fracturing drainage and production. This is crucial for optimizing geological and engineering design and achieving economical and efficient development of oil and gas wells. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for monitoring the fracturing production profile of oil and gas wells using trace tracers, which can effectively exert the monitoring function of the tracer and better obtain the fracturing production profile of oil and gas wells including tight oil and gas and shale oil and gas reservoirs.

[0006] To achieve the above object, the present invention provides a method for monitoring the production profile of oil and gas well fracturing using trace tracers, which comprises the following steps:

[0007] (1) Determine the type and model of tracer used in each fracturing stage of the target well;

[0008] The types of trace tracers used in each fracturing stage of the target well include: oil phase tracers and / or gas phase tracers, and water phase tracers;

[0009] (2) Determine the designed dosage, injection timing, and injection rate of trace tracer for each fracturing stage of the target well;

[0010] Among them, the pumping timing of the trace tracer used in each fracturing stage of the target well is:

[0011] The water phase tracer is injected during the pre-fluid stage and the sand-carrying fluid stage of the fracturing process in this fracturing section;

[0012] When the fracture extension is not carried out in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are injected in the pre-fluid stage during the fracturing process of the fracturing section;

[0013] When fracture extension is performed in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are injected in the sand-carrying fluid stage during the fracturing process of the fracturing section;

[0014] (3) During the fracturing construction of each fracturing section of the target well, the trace tracer injection operation is completed according to the determined trace tracer type and model, designed dosage, pumping timing and pumping speed;

[0015] (4) After the completion of the fracturing construction of each fracturing stage in the target well, during the post-fracturing flowback and production process, the target well sampling operation shall be carried out according to the designed sampling system;

[0016] (5) Testing each sample obtained from the target well sampling operation; determining the type and content of the trace tracer contained in each sample;

[0017] (6) Determine the production profile of each fracturing section of the target well based on the type and content of the trace tracer contained in each sample, as well as the output data during post-fracturing flowback and production.

[0018] In the above-mentioned method of monitoring the fracturing output profile of oil and gas wells using trace tracers, the injection timing of the tracers, especially the injection timing of the oil-phase tracers and the gas-phase tracers, is optimized, which can better ensure that the tracers fully enter all fracture-affected areas and more effectively play the monitoring role of the tracers. In the prior art, oil-phase tracers and gas-phase tracers are usually injected in the pre-stage. According to the research on fracturing simulation and fracture monitoring results, this method is applicable to fracturing tracer monitoring of medium and high permeability reservoirs, but has limitations when used for fracturing tracer monitoring of low permeability and ultra-low permeability reservoirs such as tight oil and gas, shale oil and gas. The reason is that low permeability and ultra-low permeability reservoirs not only extend fractures in the pre-fluid stage, but also further extend fractures in the sand-carrying fluid stage, and even fracture extension still exists after the pump is stopped. The tracer can only effectively play a monitoring role if it is ensured to fully enter all fracture-affected areas.

[0019] In the above method of monitoring the fracturing production profile of oil and gas wells using trace tracers, the oil phase tracer is only soluble in oil, the gas phase tracer is only soluble in gas, and the water phase tracer is only soluble in water. The oil phase tracer, gas phase tracer and water phase tracer do not interfere with each other.

[0020] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, specifically, in step (1), the type of trace tracer used in each fracturing stage of the target well is determined to satisfy:

[0021] The oil phase tracer model used in a fracturing stage of a target well is unique (i.e., only one type of oil phase tracer can be used), the gas phase tracer model used is unique (i.e., only one type of gas phase tracer can be used), and the water phase tracer model used is unique (i.e., only one type of water phase tracer can be used);

[0022] Different types of oil phase tracers, gas phase tracers, and water phase tracers are used in different fracturing stages of a target well;

[0023] The oil phase tracer model used in the target well is different from that of the adjacent wells, the gas phase tracer model used in the target well is different from that of the adjacent wells, and the water phase tracer model used in the target well is different from that of the adjacent wells.

[0024] In the above-mentioned method for monitoring the production profile of oil and gas well fracturing using a trace tracer, preferably, in the process of determining the specific type of trace tracer used in each fracturing stage of the target well in step (1), formation water in the target monitoring area of ​​the target well is sampled and analyzed, and the specific type of the appropriate trace tracer is selected based on the analysis results;

[0025] In this preferred technical solution, the types of trace elements contained in the formation water of the target well and the fracturing return fluid or produced water of the adjacent wells are determined by testing them, and the characterizing elements used in the testing of the selected target well trace tracer are different from the trace elements determined in the formation water of the target well and the fracturing return fluid or produced water of the adjacent wells.

[0026] In the above method of monitoring the production profile of oil and gas well fracturing using a trace tracer, preferably, the determined trace tracer satisfies at least one of the following conditions:

[0027] High detection accuracy, capable of monitoring at low dosage: 0.01-0.015% dosing concentration, detection accuracy reaches 10 -9- 10 -12 ;

[0028] Good shear resistance: 153℃, 170s -1 Shearing at the same rate for 60-90 minutes without changing performance;

[0029] Acid and alkali resistance: Applicable pH value: 3-12;

[0030] Long validity period: ≥500 days.

[0031] In the above method for monitoring the production profile of oil and gas well fracturing using a trace tracer, preferably, the trace tracer is a nano-particle trace tracer with ultra-low surface and interfacial tension characteristics; wherein the ultra-low surface and interfacial tension characteristics refer to the trace tracer having a surface tension of less than 2×10 -2 Ultra-low interfacial tension of mN / m.

[0032] In order to make the nano-particle trace tracer have ultra-low surface and interfacial tension characteristics, the nano-particle trace tracer can be surface treated during the production process; the surface of nano-particles with ultra-low surface and interfacial tension characteristics is easier to disperse and diffuse, which can better ensure the tracing effect.

[0033] In the above method of monitoring the production profile of oil and gas well fracturing using a trace tracer, preferably, the trace tracer is subjected to ultrasonic vibration before injection to achieve sufficient dispersion of the particles.

[0034] In the above-mentioned method for monitoring the fracturing output profile of an oil and gas well using a trace tracer, in order to facilitate the determination of the trace tracer model used in each fracturing stage of a target well, an oil-phase tracer model pool, a water-phase tracer model pool, and a gas-phase tracer model pool can be established respectively. When determining the trace tracer model used in each fracturing stage of a target well, the trace tracer model can be selected from the established oil-phase tracer model pool, the water-phase tracer model pool, and the gas-phase tracer model pool.

[0035] In a specific embodiment, the oil phase tracer is selected from 55 trace oil phase tracers, the gas phase tracer is selected from 42 trace gas phase tracers, and the water phase tracer is selected from 55 trace water phase tracers, which can meet the highest process requirements.

[0036] In the above-mentioned method for monitoring the production profile of oil and gas well fracturing using trace tracers, the oil phase tracers, gas phase tracers, and water phase tracers used are all trace tracers currently available in the art. Those skilled in the art can reasonably select appropriate oil phase tracers, gas phase tracers, and water phase tracers according to operational requirements, as long as the objectives of the present invention can be achieved.

[0037] Water phase tracers can be chemically synthesized rare earth element and metal element water phase tracers; oil phase tracers can be nano-capsule oil phase tracers with rare earth elements and metal elements encapsulated in lipophilic polymer capsules; gas phase tracers can be synthetic gas phase tracers of hydrocarbons, esters and alcohols, which can be vaporized and dispersed into the gas in the formation.

[0038] In the above-mentioned method for monitoring the fracturing output profile of an oil and gas well using a trace tracer, preferably, in step (2), when determining the pumping timing of the trace tracer used in each fracturing section of the target well, when a fracturing section of the target well is temporarily plugged and fractured during the fracturing process, the pumping timing of the trace tracer used in the fracturing section of the target well is:

[0039] The water phase tracer is injected in each pre-fluid stage and each sand-carrying fluid stage of the fracturing process of the fracturing section;

[0040] When the fracture extension is not carried out in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are respectively injected in each pre-fluid stage during the fracturing process of the fracturing section;

[0041] When the fracture is extended in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are respectively injected in each sand-carrying fluid stage during the fracturing process of the fracturing section;

[0042] Temporary plugging has become the main technology for volume fracturing in conventional oil and gas, tight oil and gas, and shale oil and gas. Conventional tracer injection timing has limitations for monitoring the temporary plugging fracturing process. Some perforation clusters or fracture areas are opened and expanded after temporary plugging. Conventional injection schemes can only monitor the fracture-affected areas before temporary plugging, and cannot monitor the newly opened fracture-affected areas after temporary plugging. In order to comprehensively and effectively monitor the newly opened fracture-affected areas before and after temporary plugging, the above-mentioned preferred technical scheme is proposed, which injects tracers before and after temporary plugging respectively to track the effect of new fractures after temporary plugging and evaluate the effectiveness of the temporary plugging process.

[0043] In the above-mentioned method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, in step (2), the water phase tracer is injected during the pre-fluid stage and the sand-carrying fluid stage, and the water phase tracer is injected throughout the pre-fluid stage and the sand-carrying fluid stage.

[0044] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, in step (2), the oil phase tracer and the gas phase tracer are injected during the pre-fluid stage. The oil phase tracer and the gas phase tracer are injected throughout the pre-fluid stage.

[0045] In the above-mentioned method for monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, in step (2), the oil phase tracer and the gas phase tracer are injected in the sand-carrying fluid stage, and the injection of the oil phase tracer and the gas phase tracer is started when sand is continuously added in the sand-carrying fluid stage and is stopped when 2 / 3 of the sand-carrying fluid is injected.

[0046] In the above-mentioned method for monitoring the fracturing output profile of an oil and gas well using a trace tracer, preferably, in step (2), in the process of determining the designed amount of the trace tracer used in each fracturing section of the target well, the designed amount of the water phase tracer is determined based on the heterogeneity characterization parameters of the formation in the fracturing section of the target well, the designed amount of the fracturing fluid, and the minimum detection limit of the water phase tracer concentration detection instrument;

[0047] More preferably, the designed dosage of the aqueous phase tracer is calculated according to the following formula (1):

[0048] A1=α·μ1·MDL1·V p ·ε1 Formula (1)

[0049] In formula (1), A1 is the designed dosage of the water phase tracer, in kg; α is the permeability variation coefficient, in dimensionless units; μ1 is the guarantee factor, in dimensionless units, usually ranging from 2 to 5; MDL1 is the minimum detection limit of the water phase tracer concentration detection instrument, in g / mL, usually greater than or equal to 1×10 -12 Less than 10×10 -12 (ppt level); V p The sum of the designed usage of the pre-fluid and the designed usage of the sand-carrying fluid in the target well, unit: m 3 ; ε1 is the unit conversion coefficient (the coefficient used to unify the units), which is 1000 here.

[0050] In the above-mentioned method for monitoring the production profile of oil and gas well fracturing using a trace tracer, preferably, in step (2), in the process of determining the design dosage of the trace tracer used in each fracturing section of the target well, the design dosage of the gas phase tracer is determined based on the heterogeneity characterization parameters of the formation in the fracturing section of the target well and the predicted daily gas production, as well as the monitoring time and the minimum detection limit of the gas phase tracer concentration detection instrument;

[0051] More preferably, the designed dosage of the gas phase tracer is calculated according to the following formula (2):

[0052] A2=α·μ2·MDL2·Q q ·T·ε2 Formula (2)

[0053] In formula (2), A2 is the designed dosage of gas phase tracer, unit is L; α is the permeability variation coefficient, unit is dimensionless; μ2 is the guarantee factor, unit is dimensionless, usually takes a value of 2-5; MDL2 is the minimum detection limit of the gas phase tracer concentration detection instrument, unit is dimensionless, usually takes a value greater than or equal to 1×10 -9 Less than 10×10 -9 (ppb level); Q q The predicted daily gas production of the target well in this fracturing section, unit: m 3 / d; T is the monitoring time, unit is d; ε2 is the unit conversion coefficient (the coefficient used to unify the units), which is 1 here.

[0054] In the above-mentioned method for monitoring the production profile of oil and gas well fracturing using a trace tracer, preferably, in step (2), in the process of determining the design dosage of the trace tracer used in each fracturing section of the target well, the design dosage of the oil phase tracer is determined based on the heterogeneity characterization parameters of the formation in the fracturing section of the target well and the predicted daily oil production as well as the monitoring time and the minimum detection limit of the oil phase tracer concentration detection instrument;

[0055] More preferably, the designed amount of the oil phase tracer is calculated according to the following formula (3):

[0056] A3=α·μ3·MDL3·Q q ·T·ε3 Formula (3)

[0057] In formula (3), A3 is the designed dosage of oil phase tracer, in kg; α is the permeability variation coefficient, in dimensionless units; μ2 is the guarantee factor, in dimensionless units, usually ranging from 2 to 5; MDL3 is the minimum detection limit of the oil phase tracer concentration detection instrument, in g / mL, usually greater than or equal to 1×10 -12 Less than 10×10 -12 (ppt level); Q q is the predicted daily oil production of the target well in the fracturing section, in t / d; T is the monitoring time, in d; ε3 is the unit conversion coefficient (to unify the coefficient used in the units), which is 10 here. 6 .

[0058] In the above preferred technical solution, the heterogeneity characterization parameter is introduced when determining the tracer dosage, which can better adapt to the strong heterogeneity characteristics of tight oil and gas and shale oil and gas reservoirs. The determined tracer dosage can better meet the tracing needs of reservoirs with strong heterogeneity.

[0059] In the above-mentioned method for monitoring the fracturing production profile of an oil and gas well using a trace tracer, specifically, the pumping rate of the trace tracer can be determined in a conventional manner; for example, the pumping rate can be determined based on the principle of uniform injection of the trace tracer during the injection period. Specifically, the trace tracer injection duration can be determined based on the pumping timing of the trace tracer, and then the average injection rate of the trace tracer can be determined based on the injection duration and the designed dosage of the trace tracer. For another example, the pumping rate can be determined based on the principle of constant concentration of the trace tracer in the fracturing fluid during the injection period. Specifically, the total injection amount of the fracturing fluid during the injection period of the trace tracer can be determined based on the pumping timing of the trace tracer and the designed injection rate of the fracturing fluid. The injection rate of the trace tracer can be determined based on the total injection amount of the fracturing fluid during the injection period of the trace tracer, the designed dosage of the trace tracer, and the designed injection rate of the fracturing fluid.

[0060] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, the sampling system specifically includes sampling time and frequency.

[0061] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, during the sampling operation, gas sampling is performed in the following manner:

[0062] Passing gas into a sampling container containing a solid adsorbent so that the gas passes through the solid adsorbent and is discharged from the sampling container (during this process, the gas flushes the solid adsorbent so that the gas-phase tracer in the gas is adsorbed in the solid adsorbent), stopping the gas passage after a specific time, and sealing the sampling container to complete the sampling; wherein the solid adsorbent is capable of adsorbing the gas-phase tracer in the gas;

[0063] More preferably, the gas is introduced for a specific time of 1 h to 2 h;

[0064] In one embodiment, the gas sampling step includes:

[0065] A. Connect the gas sampling pipeline: connect the gas inlet of the sampling container filled with solid adsorbent to the gas outlet of the metering separator, connect the gas outlet of the sampling container filled with solid adsorbent to the gas inlet of the hydrogen sulfide absorption cell, and connect the outlet of the hydrogen sulfide absorption cell to the built-in three-phase separator;

[0066] Wherein, the solid adsorbent is arranged between the gas inlet and the gas outlet of the sampling container;

[0067] Wherein, a pressure reducing valve is provided on the connecting pipeline between the gas outlet of the sampling container containing the solid adsorbent and the gas inlet of the hydrogen sulfide absorption tank;

[0068] B. Gas sampling:

[0069] Open the pressure reducing valve and the gas outlet switch of the metering separator, and let the gas pass into the sampling container filled with solid adsorbent. The gas passes through the solid adsorbent and is discharged from the sampling container (in this process, the gas flushes the solid adsorbent so that the gas phase tracer in the gas is adsorbed in the solid adsorbent). After the gas is passed for a specific time (1h-2h), close the gas outlet switch of the metering separator and seal the sampling container to complete the sampling;

[0070] Wherein, the solid adsorbent is capable of adsorbing a gas phase tracer in the gas;

[0071] The opening degree of the gas outlet switch of the metering separator can satisfy the requirement that the airflow flowing into the sampling container can just blow up the solid adsorbent in the sampling container;

[0072] Existing gas sampling is usually carried out by directly collecting gas samples. However, the instability of the airflow can easily affect the instantaneous sampling results, thereby affecting the monitoring and analysis results. In this preferred embodiment, the gas sampling method is improved and solid adsorption method is used for gas sampling, which avoids the error of single gas sampling and makes the results closer to the actual gas production profile.

[0073] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, specifically, in the sampling operation, oil sampling and water sampling can be carried out in a conventional manner;

[0074] For example, using blowdown sampling: taking water and / or oil samples directly at the blowdown pool outlet;

[0075] For example, sampling of a metering separator: after drilling a well, water samples and / or oil samples are taken at the liquid outlet of the metering separator.

[0076] In the above-mentioned method of monitoring the production profile of oil and gas well fracturing using trace tracers, the production profile of each fracturing stage of the target well can be determined by conventional technical means in the art based on the type and content of the trace tracer contained in each sample, as well as the production data during post-fracturing flowback and production.

[0077] In one embodiment, determining the production profile of each fracture stage of the target well based on the type and content of the trace tracer contained in each sample, as well as the production data during post-fracturing flowback and production, includes:

[0078] Based on the model and content of the trace tracer contained in each sample, as well as the output data during post-fracturing flowback and production, the water, oil, and / or gas production and production time variation of each fracturing section of the target well are determined, and then the water, oil, and / or gas production contribution rate of each fracturing section of the target well, that is, the contribution time variation, is determined, and then the production profile of each fracturing section of the target well during the sampling period is determined.

[0079] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, the method further comprises:

[0080] After the completion of each fracturing stage of the target well, during the post-fracturing flowback and production process, sampling operations are carried out in the adjacent wells of the target well according to the designed sampling system; each sample obtained from the sampling operation in the adjacent well of the target well is tested to determine the type and content of the trace tracer contained in each sample, thereby judging the interwell communication between the target well and the adjacent well;

[0081] Determining the interwell communication between the target well and the adjacent wells can provide a basis for optimizing the well spacing and fracture scale, which is conducive to optimizing and improving the overall development effect.

[0082] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, in the process of determining the type and content of the trace tracer contained in each sample, the type and content of the gas phase tracer can be determined using a gas chromatograph.

[0083] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, in the process of determining the type and content of the trace tracer contained in each sample, the type and content of the oil phase tracer can be determined using an inductively coupled plasma mass spectrometer.

[0084] In the above method of monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, in the process of determining the type and content of the trace tracer contained in each sample, the type and content of the water phase tracer can be determined using an inductively coupled plasma mass spectrometer.

[0085] In the above method for monitoring the production profile of oil and gas well fracturing using trace tracers, preferably, the equipment used in step (3) includes fracturing equipment and trace tracer injection equipment; wherein the trace tracer injection equipment includes a trace tracer storage tank and a trace tracer injection pump connected to the outlet of the trace tracer storage tank;

[0086] The pump outlet of the trace tracer injection pump is connected to the inlet of the mixing tank of the sand mixing truck of the fracturing equipment; and the fracturing equipment is connected to the target well;

[0087] More preferably, the fracturing equipment includes: a fracturing fluid storage tank, a sand tank, a sand mixing truck and a fracturing truck; the fracturing fluid outlet of the fracturing fluid storage tank is connected to the fracturing fluid inlet of the sand mixing truck, the sand outlet of the sand tank is connected to the sand inlet of the sand mixing truck, the fluid outlet of the sand mixing truck is connected to the fluid inlet of the fracturing truck through a low-pressure manifold, and the fluid outlet of the fracturing truck is connected to the wellhead of the target well through a high-pressure manifold.

[0088] The inventors of the present invention have focused on the extension characteristics of tight oil and gas, shale oil and gas fractures, combined with small-scale test fracturing analysis and post-fracturing pump stop fitting analysis, analyzed parameters such as liquid efficiency and filtration coefficient, optimized the injection timing of oil-phase tracers and gas-phase tracers, and formed the method provided by the present invention for monitoring the fracturing output profile of oil and gas wells using trace tracers. During the fracturing process, this method injects different oil, gas and water trace tracers into different fracturing sections, takes oil, gas and water samples during post-fracturing drainage and production, and detects and analyzes the tracer amount in the sample. The output profile is determined in combination with post-fracturing drainage and production data, providing reference and guidance for geological and engineering design, and continuously improving development effects. The method provided by the present invention for monitoring the fracturing output profile of oil and gas wells using trace tracers can effectively exert the monitoring function of tracers and better obtain the fracturing output profile of oil and gas wells including tight oil and gas and shale oil and gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 A process flow chart of a method for monitoring the production profile of oil and gas well fracturing using trace tracers provided in an embodiment of the present invention.

[0090] Figure 2 Schematic diagram of the equipment used in the embodiment of the present invention.

[0091] Figure 3A The figure is a schematic diagram of the process of fracturing construction in a certain fracturing section according to an embodiment of the present invention.

[0092] Figure 3B This is a schematic diagram of the process of fracturing construction in a certain fracturing section according to an embodiment of the present invention.

[0093] Figure 3C The figure is a schematic diagram of the process of fracturing construction in a certain fracturing section according to an embodiment of the present invention.

[0094] Figure 4A This is a production profile diagram of a target well monitored after pressure measurement using a gas-water two-phase tracer in Example 1 of the present invention.

[0095] Figure 4B This is the interpretation result of the liquid production of the target well production profile monitored by the gas-water two-phase tracer after pressure in Example 1 of the present invention.

[0096] Figure 4C This is the interpretation result of the gas production of the target well production profile monitored by the gas-water two-phase tracer after pressure in Example 1 of the present invention.

[0097] Figure 5A Schematic diagram of the inductively coupled plasma mass spectrometer used in Example 1 of the present invention.

[0098] Figure 5B This is a gas chromatograph diagram used in Example 1 of the present invention. DETAILED DESCRIPTION

[0099] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below in conjunction with the following specific embodiments, but they should not be construed as limiting the scope of implementation of the present invention.

[0100] A specific embodiment of the present invention provides a method for monitoring the production profile of oil and gas well fracturing using trace tracers, such as Figure 1 As shown, the method includes:

[0101] Step S1: determining the type and model of trace tracers used in each fracturing stage of the target well;

[0102] The types of trace tracers used in each fracturing stage of the target well include: oil phase tracers and / or gas phase tracers, and water phase tracers;

[0103] Step S2: determining the designed dosage, injection timing, and injection speed of the trace tracer used in each fracturing stage of the target well;

[0104] Among them, the pumping timing of the trace tracer used in each fracturing stage of the target well is:

[0105] The water phase tracer is injected during the pre-fluid stage and the sand-carrying fluid stage of the fracturing process in this fracturing section;

[0106] When the fracture extension is not carried out in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are injected in the pre-fluid stage during the fracturing process of the fracturing section;

[0107] When fracture extension is performed in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are injected in the sand-carrying fluid stage during the fracturing process of the fracturing section;

[0108] Step S3: During the fracturing construction of each fracturing stage of the target well, the trace tracer is injected according to the determined type and model, designed dosage, pumping timing and pumping speed of the trace tracer;

[0109] Step S4: After the target well completes the fracturing construction of each fracturing stage, during the post-fracturing flowback and production process, the target well is sampled according to the designed sampling system;

[0110] Step S5: testing each sample obtained from the target well sampling operation; determining the type and content of the trace tracer contained in each sample;

[0111] Step S6: Determine the production profile of each fracturing stage of the target well based on the type and content of the trace tracer contained in each sample, as well as the output data during post-fracturing flowback and production.

[0112] Furthermore, the oil phase tracer only dissolves in oil, the gas phase tracer only dissolves in gas, and the water phase tracer only dissolves in water. The oil phase tracer, the gas phase tracer, and the water phase tracer do not interfere with each other.

[0113] Furthermore, the model of the trace tracer used in each fracturing stage of the target well is determined to meet the following requirements:

[0114] The oil phase tracer model used in a fracturing stage of a target well is unique (i.e., only one type of oil phase tracer can be used), the gas phase tracer model used is unique (i.e., only one type of gas phase tracer can be used), and the water phase tracer model used is unique (i.e., only one type of water phase tracer can be used);

[0115] Different types of oil phase tracers, gas phase tracers, and water phase tracers are used in different fracturing stages of a target well;

[0116] The oil phase tracer model used in the target well is different from that of the adjacent wells, the gas phase tracer model used in the target well is different from that of the adjacent wells, and the water phase tracer model used in the target well is different from that of the adjacent wells.

[0117] Furthermore, in the process of determining the specific type of trace tracer to be used in each fracturing stage of the target well, the formation water in the target monitoring area of ​​the target well is sampled and analyzed, and the specific type of the appropriate trace tracer is selected based on the analysis results;

[0118] In this process, the types of trace elements contained in the formation water of the target well and the fracturing return fluid or produced water of the adjacent wells are determined by testing. The characterizing elements used in the testing of the selected target well trace tracer are different from the trace elements in the determined formation water of the target well and the fracturing return fluid or produced water of the adjacent wells.

[0119] Furthermore, the determined trace tracer satisfies at least one of the following conditions:

[0120] (1) High detection accuracy, capable of monitoring at low dosage: the dosage concentration is 0.01-0.015%, and the detection accuracy reaches 10 -9- 10 -12 ;

[0121] (2) Good shear resistance: 153℃, 170s -1 Shearing at the same rate for 60-90 minutes without changing performance;

[0122] (3) Acid and alkali resistance: Applicable pH value: 3-12;

[0123] (4) Long validity period: Validity period ≥ 500 days.

[0124] Furthermore, the trace tracer determined is a nano-particle trace tracer with ultra-low surface and interfacial tension characteristics; wherein the ultra-low surface and interfacial tension characteristics refer to the trace tracer having a surface tension of less than 2×10 -2 Ultra-low interfacial tension of mN / m.

[0125] Furthermore, the trace tracer is subjected to ultrasonic vibration before injection to achieve full dispersion of the particles.

[0126] Furthermore, an oil phase tracer model pool, a water phase tracer model pool, and a gas phase tracer model pool are established respectively. When determining the trace tracer model used in each fracturing stage of the target well, selection is made from the established oil phase tracer model pool, water phase tracer model pool, and gas phase tracer model pool;

[0127] Among them, the oil phase tracer is selected from 55 trace oil phase tracers, the gas phase tracer is selected from 42 trace gas phase tracers, and the water phase tracer is selected from 55 trace water phase tracers;

[0128] Among them, the oil phase tracer, gas phase tracer and water phase tracer are all trace tracers available in the art. Those skilled in the art can reasonably select appropriate oil phase tracers, gas phase tracers and water phase tracers according to the operational requirements, as long as they can achieve the purpose of the present invention;

[0129] For example, water-phase tracers can be selected from chemically synthesized rare earth elements and metal elements;

[0130] For example, the oil phase tracer can be a nano-capsule oil phase tracer containing rare earth elements and metal elements in lipophilic polymer capsules;

[0131] For example, the gas phase tracer may be a synthetic gas phase tracer of hydrocarbons, esters, or alcohols, which can be vaporized and dispersed into the gas in the formation.

[0132] Furthermore, when determining the pumping timing of the trace tracer used in each fracturing stage of the target well, when a fracturing stage of the target well is temporarily plugged and fracturing during the fracturing process, the pumping timing of the trace tracer used in the fracturing stage of the target well is:

[0133] The water phase tracer is injected in each pre-fluid stage and each sand-carrying fluid stage of the fracturing process of the fracturing section;

[0134] When the fracture extension is not carried out in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are respectively injected in each pre-fluid stage during the fracturing process of the fracturing section;

[0135] When fracture extension is performed in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and the gas phase tracer are respectively injected in each sand-carrying fluid stage during the fracturing process of the fracturing section.

[0136] Furthermore, the water phase tracer is injected during the pre-fluid stage and the sand-carrying fluid stage. The water phase tracer is injected during the entire pre-fluid stage and the entire sand-carrying fluid stage.

[0137] Furthermore, the oil phase tracer and the gas phase tracer are injected during the pre-pad stage. The oil phase tracer and the gas phase tracer are injected throughout the pre-pad stage.

[0138] Furthermore, the oil phase tracer and the gas phase tracer are injected in the sand carrying fluid stage. The oil phase tracer and the gas phase tracer are injected when sand is continuously added in the sand carrying fluid stage and the injection is stopped when 2 / 3 of the sand carrying fluid is injected.

[0139] In a specific embodiment, when the sand-carrying fluid stage of a certain fracturing section of a target well only performs fracture filling without fracture extension, and the fracturing section does not undergo temporary plugging fracturing, the injection timing of the trace tracer in the fracturing section of the target well is:

[0140] The water phase tracer is injected throughout the pre-fluid stage and the sand-carrying fluid stage of the fracturing process of the fracturing section (i.e., the water phase tracer is injected from the beginning of the pre-fluid injection until the sand-carrying fluid injection is completed and the water phase tracer injection is stopped);

[0141] The oil phase tracer and the gas phase tracer are injected throughout the pre-pad stage of the fracturing process of the fracturing section (i.e., the oil phase tracer and the gas phase tracer are injected from the beginning of the pre-pad injection until the pre-pad injection is completed and the oil phase tracer and the gas phase tracer are stopped);

[0142] like Figure 3A As shown, during the fracturing construction of the target well, the injection operation of the trace tracer is completed according to the determined type and model of the trace tracer, the designed dosage, the injection timing and the injection speed, including the following specific steps:

[0143] 1) Pre-pad stage: Starting from the pre-pad stage, water phase tracer injection is carried out according to the model, designed dosage and pumping speed of the water phase tracer; starting from the pre-pad stage, oil phase tracer and / or gas phase tracer injection is carried out according to the model, designed dosage and pumping speed of the oil phase tracer and / or gas phase tracer; at the end of the pre-pad stage, all oil phase tracer and / or gas phase tracer injection is completed, and the water phase tracer injection operation is continued;

[0144] 2) Sand-carrying fluid stage: During the sand-carrying fluid stage, the water-phase tracer injection operation is continued according to the model, designed dosage and pumping speed of the water-phase tracer. At the end of the sand-carrying fluid stage, all water-phase tracer injection is completed;

[0145] 3) Displacement fluid stage: Use fracturing fluid for displacement to ensure that all tracers enter the formation smoothly.

[0146] In a specific embodiment, when fracture extension occurs during the sand-carrying fluid stage of a certain fracturing section of a target well and temporary plugging fracturing is not performed on the fracturing section, the injection timing of the trace tracer in the fracturing section of the target well is:

[0147] The water phase tracer is injected throughout the pre-fluid stage and the sand-carrying fluid stage of the fracturing process of the fracturing section (i.e., the water phase tracer is injected from the beginning of the pre-fluid injection until the sand-carrying fluid injection is completed and the water phase tracer injection is stopped);

[0148] The oil phase tracer and gas phase tracer are injected when the sand is continuously added in the sand carrying fluid stage and the injection is stopped when 2 / 3 of the sand carrying fluid is injected;

[0149] like Figure 3B As shown, during the fracturing construction of the target well, the injection operation of the trace tracer is completed according to the determined type and model of the trace tracer, the designed dosage, the injection timing and the injection speed, including the following specific steps:

[0150] 1) Pre-pad stage: Starting from the pre-pad stage, water-phase tracer injection is carried out according to the model, designed dosage and pumping speed of the water-phase tracer; the water-phase tracer injection operation is continued at the end of the pre-pad stage;

[0151] 2) Sand-carrying fluid stage: During the sand-carrying fluid stage, the water-phase tracer injection operation is continued according to the model, designed dosage and pumping speed of the water-phase tracer. At the end of the sand-carrying fluid stage, all water-phase tracer injection is completed. During the continuous sand addition in the sand-carrying fluid stage, the oil-phase tracer and / or gas-phase tracer injection is started according to the model, designed dosage and pumping speed of the oil-phase tracer and / or gas-phase tracer. The oil-phase tracer and / or gas-phase tracer injection is stopped when 2 / 3 of the sand-carrying fluid volume has been injected, and all oil-phase tracer and / or gas-phase tracer injection is completed.

[0152] 3) Displacement fluid stage: Use fracturing fluid for displacement to ensure that all tracers enter the formation smoothly.

[0153] In a specific embodiment, when fracture extension is performed in the sand-carrying fluid stage during the fracturing process of a certain fracturing section of a target well and a temporary plugging fracturing is performed on the fracturing section, the injection timing of the trace tracer in the fracturing section of the target well is:

[0154] The water-phase tracer is injected throughout the two pre-flush stages and the two sand-carrying fluid stages of the fracturing process of the fracturing section (i.e., the water-phase tracer is injected from the first pre-flush injection until the first sand-carrying fluid injection is completed and then stopped; the water-phase tracer is injected from the second pre-flush injection until the second sand-carrying fluid injection is completed and then stopped);

[0155] The oil phase tracer and the gas phase tracer are injected from the time of continuous sand addition in the two sand carrying fluid stages until 2 / 3 of the sand carrying fluid volume is injected and then the injection is stopped (i.e., the oil phase tracer and the gas phase tracer are injected from the time of continuous sand addition in the first sand carrying fluid stage until 2 / 3 of the sand carrying fluid volume is injected and then the injection of the oil phase tracer and the gas phase tracer is stopped; the oil phase tracer and the gas phase tracer are injected from the time of continuous sand addition in the second sand carrying fluid stage until 2 / 3 of the sand carrying fluid volume is injected and then the injection of the oil phase tracer and the gas phase tracer is stopped);

[0156] like Figure 3C As shown, during the fracturing construction of the target well, the injection operation of the trace tracer is completed according to the determined type and model of the trace tracer, the designed dosage, the injection timing and the injection speed, including the following specific steps:

[0157] 1) Pre-pad stage: Starting from the pre-pad stage, water-phase tracer injection is carried out according to the model, designed dosage and pumping speed of the water-phase tracer; the water-phase tracer injection operation is continued at the end of the pre-pad stage;

[0158] 2) Sand-carrying fluid stage: During the sand-carrying fluid stage, continue to inject the water-phase tracer according to the model, designed dosage, and pumping speed of the water-phase tracer, and stop injecting the water-phase tracer at the end of the sand-carrying fluid stage; during the continuous sand addition in the sand-carrying fluid stage, start injecting the oil-phase tracer and / or gas-phase tracer according to the model, designed dosage, and pumping speed of the oil-phase tracer and / or gas-phase tracer, and stop injecting the oil-phase tracer and / or gas-phase tracer when 2 / 3 of the sand-carrying fluid volume has been injected;

[0159] 3) Temporary plugging stage between layers (sections): Temporary plugging balls (agents) are used to temporarily plug the sand-filled reformed perforation clusters or seams, and pressurize new perforation clusters;

[0160] 4) Pre-pad stage: Starting from the pre-pad stage, water-phase tracer injection is carried out according to the model, designed dosage and pumping speed of the water-phase tracer; the water-phase tracer injection operation is continued at the end of the pre-pad stage;

[0161] 5) Sand-carrying fluid stage: During the sand-carrying fluid stage, the water-phase tracer injection operation is continued according to the model, designed dosage, and pumping speed of the water-phase tracer. The water-phase tracer injection is stopped at the end of the sand-carrying fluid stage, and all water-phase tracer injections are completed. During the sand-carrying fluid stage, when sand is continuously added, the oil-phase tracer and / or gas-phase tracer injection is started according to the model, designed dosage, and pumping speed of the oil-phase tracer and / or gas-phase tracer. The oil-phase tracer and / or gas-phase tracer injection is stopped when 2 / 3 of the sand-carrying fluid volume is injected, and all oil-phase tracer and / or gas-phase tracer injections are completed.

[0162] 6) Displacement fluid stage: Use fracturing fluid for displacement to ensure that all tracers enter the formation smoothly.

[0163] Furthermore, in determining the designed dosage of the trace tracer used in each fracturing stage of the target well, the designed dosage of the water phase tracer is determined based on the heterogeneity characterization parameters of the formation in the fracturing stage of the target well, the designed dosage of the fracturing fluid, and the minimum detection limit of the water phase tracer concentration detection instrument;

[0164] Furthermore, the designed dosage of the aqueous phase tracer is calculated according to the following formula:

[0165] A1=α·μ1·MDL1·V p ·ε1

[0166] Where A1 is the designed dosage of the water phase tracer, in kg; α is the coefficient of variation of permeability, in dimensionless units; μ1 is the guarantee factor, in dimensionless units, usually ranging from 2 to 5; MDL1 is the minimum detection limit of the water phase tracer concentration detection instrument, in g / mL, usually greater than or equal to 1×10 -12 Less than 10×10 -12 (ppt level); V p The sum of the designed usage of the pre-fluid and the designed usage of the sand-carrying fluid for the target well in the fracturing section, unit: m 3 ; ε1 is the unit conversion coefficient (the coefficient used to unify the units), which is taken as 1000 here.

[0167] Furthermore, in determining the design dosage of the trace tracer used in each fracturing stage of the target well, the design dosage of the gas phase tracer is determined based on the heterogeneity characterization parameters of the formation in the fracturing stage of the target well, the predicted daily gas production, the monitoring time, and the minimum detection limit of the gas phase tracer concentration detection instrument;

[0168] Furthermore, the designed dosage of the gas phase tracer is calculated according to the following formula:

[0169] A2=α·μ2·MDL2·Q q ·T·ε2

[0170] Where A2 is the designed dosage of the gas phase tracer, in L; α is the coefficient of variation of permeability, in dimensionless units; μ2 is the guarantee factor, in dimensionless units, usually ranging from 2 to 5; MDL2 is the minimum detection limit of the gas phase tracer concentration detection instrument, in dimensionless units, usually ranging from 1×10 -9 Less than 10×10 -9 (ppb level); Q q The predicted daily gas production of the target well in this fracturing section, unit: m 3 / d; T is the monitoring time, unit is d; ε2 is the unit conversion coefficient (the coefficient used to unify the units), which is 1 here.

[0171] Furthermore, in determining the design dosage of the trace tracer used in each fracturing stage of the target well, the design dosage of the oil phase tracer is determined based on the heterogeneity characterization parameters of the formation in the fracturing stage of the target well, the predicted daily oil production, the monitoring time, and the minimum detection limit of the oil phase tracer concentration detection instrument;

[0172] Furthermore, the designed dosage of the oil phase tracer is calculated according to the following formula:

[0173] A3=α·μ3·MDL3·Q q ·T·ε3

[0174] Where A3 is the designed dosage of oil phase tracer, in kg; α is the coefficient of variation of permeability, in dimensionless units; μ2 is the guarantee factor, in dimensionless units, usually ranging from 2 to 5; MDL3 is the minimum detection limit of the oil phase tracer concentration detection instrument, in dimensionless units, usually ranging from 1×10 -12 Less than 10×10 -12 (ppt level); Q q is the predicted daily oil production of the target well in the fracturing section, in t / d; T is the monitoring time, in d; ε3 is the unit conversion coefficient (to unify the coefficient used in the units), which is 10 here. 6 .

[0175] Furthermore, the pumping speed of the trace tracer can be determined in a conventional manner; for example, the pumping speed can be determined based on the principle of uniform injection of the trace tracer during the injection period. Specifically, the trace tracer injection time can be determined based on the pumping timing of the trace tracer, and then the average injection speed of the trace tracer can be determined based on the injection time and the designed dosage of the trace tracer. For another example, the pumping speed can be determined based on the principle of constant concentration of the trace tracer in the fracturing fluid during the injection period. Specifically, the total injection amount of the fracturing fluid during the injection period of the trace tracer can be determined based on the pumping timing of the trace tracer and the designed injection speed of the fracturing fluid. The injection speed of the trace tracer can be determined based on the total injection amount of the fracturing fluid during the injection period of the trace tracer, the designed dosage of the trace tracer and the designed injection speed of the fracturing fluid.

[0176] Furthermore, the sampling system includes the sampling time and frequency;

[0177] For example, water sample: return liquid volume 40m 3 Take one;

[0178] Gas sample: gas production 10000m 3 Take one;

[0179] Oil sample: flowback volume 40m 3 Take one;

[0180] For example, water samples: 1-15 days, 4 times / day, sampling once every 6 hours; 16-30 days, 2 times / day, sampling once every 12 hours; after 30 days, 1 time / day, sampling once every 24 hours;

[0181] Oil sampling: 1-15 days, 4 times / day, 1 sampling every 6 hours; 16-30 days, 2 times / day, 1 sampling every 12 hours; after 30 days, 1 time / day, 24 hours;

[0182] Gas sampling: 1-15 days, 4 times / day, sampling once every 6 hours; 16-30 days, 2 times / day, sampling once every 12 hours; after 30 days, 1 time / day, sampling once every 24 hours.

[0183] Furthermore, in the sampling operation, gas sampling is performed in the following manner:

[0184] Passing gas into a sampling container containing a solid adsorbent so that the gas passes through the solid adsorbent and is discharged from the sampling container (during this process, the gas flushes the solid adsorbent so that the gas-phase tracer in the gas is adsorbed in the solid adsorbent), stopping the gas passage after a specific time, and sealing the sampling container to complete the sampling; wherein the solid adsorbent is capable of adsorbing the gas-phase tracer in the gas;

[0185] Furthermore, the gas is introduced for a specific time of 1 h to 2 h;

[0186] For example, gas sampling steps include:

[0187] A. Connect the gas sampling pipeline: connect the gas inlet of the sampling container filled with solid adsorbent to the gas outlet of the metering separator, connect the gas outlet of the sampling container filled with solid adsorbent to the gas inlet of the hydrogen sulfide absorption cell, and connect the outlet of the hydrogen sulfide absorption cell to the built-in three-phase separator;

[0188] Wherein, the solid adsorbent is arranged between the gas inlet and the gas outlet of the sampling container;

[0189] Wherein, a pressure reducing valve is provided on the connecting pipeline between the gas outlet of the sampling container containing the solid adsorbent and the gas inlet of the hydrogen sulfide absorption tank;

[0190] B. Gas sampling:

[0191] Open the pressure reducing valve and the gas outlet switch of the metering separator, and let the gas pass into the sampling container filled with solid adsorbent. The gas passes through the solid adsorbent and is discharged from the sampling container (in this process, the gas flushes the solid adsorbent so that the gas phase tracer in the gas is adsorbed in the solid adsorbent). After the gas is passed for a specific time (1h-2h), close the gas outlet switch of the metering separator and seal the sampling container to complete the sampling;

[0192] Wherein, the solid adsorbent is capable of adsorbing a gas phase tracer in the gas;

[0193] The opening degree of the gas outlet switch of the metering separator can satisfy the requirement that the airflow flowing into the sampling container can just blow up the solid adsorbent in the sampling container;

[0194] Existing gas sampling is usually carried out by directly collecting gas samples. However, the instability of the airflow can easily affect the instantaneous sampling results, thereby affecting the monitoring and analysis results. In this preferred embodiment, the gas sampling method is improved and solid adsorption method is used for gas sampling, which avoids the error of single gas sampling and makes the results closer to the actual gas production profile.

[0195] Furthermore, in the sampling operation, oil sampling and water sampling can be carried out in a conventional manner;

[0196] For example, using blowdown sampling: taking water and / or oil samples directly at the blowdown pool outlet;

[0197] For example, sampling of a metering separator: after drilling a well, water samples and / or oil samples are taken at the liquid outlet of the metering separator.

[0198] Furthermore, the production profile of each fracturing stage of the target well can be determined by conventional techniques in the art based on the type and content of the trace tracer contained in each sample, as well as the output data during post-fracturing flowback and production.

[0199] For example, based on the type and content of trace tracers contained in each sample, as well as the output data during post-fracturing flowback and production, the output profile of each fracturing stage of the target well is determined to include:

[0200] Based on the type and content of the trace tracer contained in each sample, as well as the output data during post-fracturing flowback and production, the water, oil, and / or gas production and the time-varying production of each fractured section of the target well are determined, and then the water, oil, and / or gas production contribution rate, i.e., the time-varying contribution, of each fractured section of the target well is determined, and then the production profile of each fractured section of the target well during the sampling period is determined;

[0201] The output data during post-pressure flowback and production are preferably the output data during sampling operations, including the production rate and cumulative production of oil, water, and / or gas, including wellhead pressure and time.

[0202] Furthermore, the method further comprises:

[0203] After the completion of each fracturing stage of the target well, during the post-fracturing flowback and production process, sampling operations are carried out in the adjacent wells of the target well according to the designed sampling system; each sample obtained from the sampling operation in the adjacent well of the target well is tested to determine the type and content of the trace tracer contained in each sample, thereby judging the interwell communication between the target well and the adjacent well;

[0204] Determining the interwell communication between the target well and the adjacent wells can provide a basis for optimizing the well spacing and fracture scale, which is conducive to optimizing and improving the overall development effect.

[0205] Furthermore, in the process of determining the type and content of the trace tracer contained in each sample, the type and content of the gas phase tracer can be determined using a gas chromatograph.

[0206] Furthermore, in the process of determining the type and content of the trace tracer contained in each sample, the type and content of the oil phase tracer can be determined using an inductively coupled plasma mass spectrometer.

[0207] Furthermore, in the process of determining the type and content of the trace tracer contained in each sample, the type and content of the aqueous phase tracer can be determined using an inductively coupled plasma mass spectrometer.

[0208] Furthermore, if Figure 2As shown, the equipment used in step S3 includes fracturing equipment and trace tracer injection equipment; wherein, the trace tracer injection equipment includes a trace tracer storage tank and a trace tracer injection pump connected to the outlet of the trace tracer storage tank;

[0209] The pump outlet of the trace tracer injection pump is connected to the inlet of the mixing tank of the sand mixing truck of the fracturing equipment; and the fracturing equipment is connected to the target well;

[0210] More preferably, the fracturing equipment includes: a fracturing fluid storage tank, a sand tank, a sand mixing truck and a fracturing truck; the fracturing fluid outlet of the fracturing fluid storage tank is connected to the fracturing fluid inlet of the sand mixing truck, the sand outlet of the sand tank is connected to the sand inlet of the sand mixing truck, the fluid outlet of the sand mixing truck is connected to the fluid inlet of the fracturing truck via a low-pressure manifold, and the fluid outlet of the fracturing truck is connected to the wellhead of the target well via a high-pressure manifold;

[0211] Among them, the fracturing equipment may further include fire trucks, ambulances, blowers, instrument vehicles, wind vanes, blower lines, etc.

[0212] Example 1

[0213] This embodiment provides a method for monitoring the production profile of oil and gas well fracturing using trace tracers.

[0214] The target well is a tight gas well with a total of 23 fracturing stages. During the fracturing process, crack extension will occur in each fracturing stage of the target well during the sand-carrying fluid stage.

[0215] The method includes:

[0216] 1. Project design:

[0217] 1. Determine the type and model of trace tracer used in each fracturing stage of the target well;

[0218] The types of trace tracers used in each fracturing stage of the target well include: gas phase tracers and water phase tracers;

[0219] Sampling and analysis of formation water in the target well and target monitoring area are performed. Based on the analysis results, the specific model of the appropriate trace tracer is selected. The determined trace tracer meets the following conditions:

[0220] (1) High detection accuracy, capable of monitoring at low dosage: the dosage concentration is 0.01-0.015%, and the detection accuracy reaches 10 -9- 10 -12 ;

[0221] (2) Good shear resistance: 153℃, 170s -1 Shearing at the same rate for 60-90 minutes without changing performance;

[0222] (3) Acid and alkali resistance: Applicable pH value: 3-12;

[0223] (4) Long validity period: ≥500 days;

[0224] (5) Nano-particle trace tracers with ultra-low surface and interfacial tension characteristics; wherein the ultra-low surface and interfacial tension characteristics refer to trace tracers with a surface tension of less than 2×10 -2 Ultra-low interfacial tension of mN / m;

[0225] (6) Only one type of gas phase tracer can be used in one fracturing section of the target well, and only one type of water phase tracer can be used in one fracturing section;

[0226] (7) The characterizing elements used in the analysis of the selected trace tracer are different from the types of trace elements contained in the formation water of the target monitoring area of ​​the target well;

[0227] Different types of gas phase tracers and water phase tracers were used in different fracturing stages of the target well;

[0228] The gas phase tracer model used in the target well is different from that in the adjacent wells, and the water phase tracer model used is different from that in the adjacent wells;

[0229] The 23 fracturing stages of the target well in this embodiment require a total of 23 gas-phase tracers and 23 water-phase tracers (the gas-phase tracers and water-phase tracers used in this embodiment are trace tracers used in the art), and each fracturing stage requires one gas-phase tracer and one water-phase tracer.

[0230] 2. Determine the designed dosage, injection timing, and injection rate of trace tracer for each fracturing stage of the target well;

[0231] The designed dosage of the aqueous phase tracer is calculated according to the following formula:

[0232] A1=α·μ1·MDL1·V p ·ε1

[0233] Where A1 is the designed dosage of the water phase tracer, in kg; α is the permeability variation coefficient, in dimensionless units; μ1 is the guarantee factor, in dimensionless units, with a value of 2; MDL1 is the minimum detection limit of the water phase tracer concentration detection instrument, in g / mL, with a value of 10 -12 ; V p The sum of the designed usage of the pre-fluid and the designed usage of the sand-carrying fluid for the target well in the fracturing section, unit: m 3 ; ε1 is the unit conversion coefficient (the coefficient used to unify the units), which is taken as 1000 here;

[0234] The designed dosage of gas phase tracer is calculated according to the following formula:

[0235] A2=α·μ2·MDL2·Q q ·T·ε2

[0236] Where A2 is the designed dosage of the gas phase tracer, in L; α is the coefficient of variation of permeability, in dimensionless units; μ2 is the guarantee factor, in dimensionless units, with a value of 2; MDL2 is the minimum detection limit of the gas phase tracer concentration detection instrument, in dimensionless units, with a value of 10 -9 ;Q q The predicted daily gas production of the target well in this fracturing section, unit: m 3 / d; T is the monitoring time, unit is d; ε2 is the unit conversion coefficient, here it is 1;

[0237] Among them, the pumping timing of the trace tracer used in each fracturing stage of the target well is:

[0238] For each fracturing section that does not require temporary plugging during the fracturing process:

[0239] The water phase tracer is injected throughout the pre-fluid stage and the sand-carrying fluid stage of the fracturing process of the fracturing section (i.e., the water phase tracer is injected from the beginning of the pre-fluid injection until the sand-carrying fluid injection is completed and the water phase tracer injection is stopped);

[0240] The gas phase tracer is injected when the sand is continuously added in the sand-carrying fluid stage and is stopped when 2 / 3 of the sand-carrying fluid is injected;

[0241] For each fracturing section that needs temporary plugging during the fracturing process:

[0242] The water phase tracer is injected throughout the entire pre-fluid stage and the entire sand-carrying fluid stage of the fracturing process of the fracturing section (i.e., in each fracturing, the water phase tracer is injected from the beginning of the pre-fluid injection until the sand-carrying fluid injection is completed and the water phase tracer injection is stopped);

[0243] The gas phase tracer is injected when the sand is continuously added in each sand-carrying fluid stage and stops when 2 / 3 of the sand-carrying fluid is injected;

[0244] The pumping rate is determined in a conventional manner; specifically, the pumping rate is determined based on the principle that the concentration of the trace tracer in the fracturing fluid is constant during the injection period, the total injection amount of the fracturing fluid during the trace tracer injection period is determined based on the pumping timing of the trace tracer and the designed injection rate of the fracturing fluid, and the injection rate of the trace tracer is determined based on the total injection amount of the fracturing fluid during the trace tracer injection period, the designed dosage of the trace tracer, and the designed injection rate of the fracturing fluid.

[0245] 3. Based on the type and model of trace tracers used in each fracturing section of the target well, as well as the designed dosage, pumping timing and pumping speed of the trace tracers used in each fracturing section of the target well, a tracer injection construction instruction manual for the fracturing process is formulated to guide the tracer injection operation.

[0246] 2. Preparation before construction:

[0247] 1. Confirm the construction well number, layer position, pumping procedure, etc. with the on-site construction commander.

[0248] 2. Preparation of materials and supporting injection:

[0249] (1) All tracers used are prepared in advance and placed in trace tracer storage tanks for easy on-site pumping;

[0250] (2) Prepare the tracer injection pumps: two BT600 peristaltic pumps with built-in 12V power supply and flow rate range of 0-4000ml / min;

[0251] Prepare auxiliary and supporting equipment: connect the injection line of the peristaltic pump, gloves, etc.;

[0252] (3) Device connection:

[0253] like Figure 2 As shown, the fracturing equipment is connected: the fracturing equipment includes a fracturing fluid storage tank, a sand tank, a sand mixing truck and a fracturing truck; the fracturing fluid outlet of the fracturing fluid storage tank is connected to the fracturing fluid inlet of the sand mixing truck, the sand outlet of the sand tank is connected to the sand inlet of the sand mixing truck, the fluid outlet of the sand mixing truck is connected to the fluid inlet of the fracturing truck via a low-pressure manifold, and the fluid outlet of the fracturing truck is connected to the wellhead of the target well via a high-pressure manifold;

[0254] Place a trace tracer storage tank (the trace tracer stock solution stored in the trace tracer storage tank has been subjected to ultrasonic vibration) next to a sand mixing truck for fracturing equipment, connect the outlet of the trace tracer storage tank to the pump inlet of a trace tracer injection pump, and connect the pump outlet of the trace tracer injection pump to the mixing tank inlet of the sand mixing truck for fracturing equipment;

[0255] The connection of the trace tracer injection pump must comply with the injection pump operating procedures:

[0256] ① Check whether the injection pump is damaged and whether the power supply voltage display is normal;

[0257] ② Connect the pipeline according to the forward and reverse signs;

[0258] ③Fix the open end of the output pipeline to prevent the pipeline from falling when the liquid sprays out;

[0259] ④ Turn on the power and wait for the injection pump to pass the self-test;

[0260] ⑤ Set the flow rate to 100ml / min, 1000ml / min, and 3000ml / min to test the injection pump;

[0261] ⑥ Input flow rate according to design requirements;

[0262] ⑦ After the injection is completed, flush the pipeline in time to prevent cross contamination.

[0263] 3. Construction steps:

[0264] During the fracturing operation of each fracturing section of the target well, the trace tracer injection operation shall be completed according to the tracer injection operation instruction during the fracturing process. In order to ensure the efficient operation, during the construction process:

[0265] (1) Technician 1 is in the fracturing command vehicle and keeps in touch with the target well management and fracturing operators at all times;

[0266] (2) Technician 2 is responsible for controlling the tracer injection pump and communicating with Technician 1 at any time;

[0267] (3) Technician 2 follows the instructions of Technician 1 and is responsible for the injection and preparation of trace tracers;

[0268] (4) Technician 1 is also responsible for filling in the on-site construction record sheet; the on-site construction record sheet shall include the date, time, injection volume of fracturing fluid, amount of sand added, injection volume of water phase tracer, injection volume of gas phase tracer and remarks of each fracturing stage tracer injection.

[0269] 4. Finishing after construction:

[0270] 1. After the construction is completed, recycle the pipelines and organize the equipment.

[0271] 2. The target well management party and the construction party provide each construction curve and data to technician 1.

[0272] 5. Sampling operation:

[0273] 1. Determine sampling requirements: filter the sample, seal it in a standard sampling bottle, mark the number, date, well number, and keep sampling records;

[0274] Among them, water sampling records include sampling bottle number, sampling time, wellhead pressure, flowback rate, and cumulative flowback volume; gas sampling records include sampling bottle number, sampling time, wellhead pressure, gas production rate, and cumulative gas production volume;

[0275] 2. Determine the sampling system:

[0276] Water samples: 1-15 days, 4 times / day, sampling once every 6 hours; 16-30 days, 2 times / day, sampling once every 12 hours; after 30 days, 1 time / day, sampling once every 24 hours;

[0277] Gas sampling: 1-15 days, 4 times / day, sampling once every 6 hours; 16-30 days, 2 times / day, sampling once every 12 hours; after 30 days, 1 time / day, sampling once every 24 hours;

[0278] 3. After the completion of the fracturing construction of each fracturing stage in the target well, during the post-fracturing flowback and production process, sampling operations shall be carried out in accordance with the designed sampling system and sampling requirements and the sampling records shall be filled out; the sampling procedures are as follows:

[0279] (1) Water sample:

[0280] During the flowback process, spray sampling is used: water samples are taken directly from the spray outlet of the spray pool;

[0281] During the production process, sampling is performed using a metering separator: water samples are taken at the liquid outlet of the metering separator;

[0282] (2) Gas sample:

[0283] A. Connect the gas sampling pipeline: connect the gas inlet of the sampling container filled with solid adsorbent to the gas outlet of the metering separator, connect the gas outlet of the sampling container filled with solid adsorbent to the gas inlet of the hydrogen sulfide absorption cell, and connect the outlet of the hydrogen sulfide absorption cell to the built-in three-phase separator;

[0284] Wherein, the solid adsorbent is arranged between the gas inlet and the gas outlet of the sampling container;

[0285] Wherein, a pressure reducing valve is provided on the connecting pipeline between the gas outlet of the sampling container containing the solid adsorbent and the gas inlet of the hydrogen sulfide absorption tank;

[0286] B. Gas sampling:

[0287] Open the pressure reducing valve and the gas outlet switch of the metering separator, and let the gas pass into the sampling container filled with solid adsorbent. The gas passes through the solid adsorbent and is discharged from the sampling container (in this process, the gas flushes the solid adsorbent so that the gas phase tracer in the gas is adsorbed in the solid adsorbent). After the gas is passed for a specific time of 1 hour, close the gas outlet switch of the metering separator and seal the sampling container to complete the sampling;

[0288] Wherein, the solid adsorbent is capable of adsorbing a gas phase tracer in the gas;

[0289] The opening degree of the gas outlet switch of the metering separator can be such that the airflow flowing into the sampling container can just blow up the solid adsorbent in the sampling container.

[0290] 6. Data Collation and Interpretation

[0291] 1. Organize the records of the construction phase and sampling operation phase.

[0292] 2. Test each sample obtained from the target well sampling operation to determine the type and content of the trace tracer contained in each sample; specifically:

[0293] Analyze the content of various tracers in each bottle of sample;

[0294] Plot the concentration change curve of each tracer over time;

[0295] Plot the time-dependent curves of all tracers;

[0296] Among them, the type and content of the aqueous phase tracer can be determined by using an inductively coupled plasma mass spectrometer (such as Figure 5A )conduct;

[0297] Among them, the type and content of the gas phase tracer can be determined by using a gas chromatograph (such as Figure 5B )conduct.

[0298] 3. Data interpretation

[0299] Interpretation is based on records from the construction and sampling phases, time-varying curves of all tracers, post-pressure flowback and production data from the target well (i.e., the target well commissioning construction curve, including construction curve diagrams and data tables), and the target well's geological data;

[0300] The geological data of the target well includes:

[0301] a. Geological development data of this block;

[0302] b. Basic drilling data and logging data of the target well;

[0303] c. Interpretation results table of target wells;

[0304] d. Production geological design and production process design.

[0305] The interpretation results include:

[0306] ① Flowback curve of each fracturing stage;

[0307] ② Analysis and evaluation of flowback trends in each fracturing stage;

[0308] ③Evaluation of gas and liquid contribution rate of each fracturing stage;

[0309] ④ Target well production profile; the results are as follows Figure 4A 、 Figure 4B 、 Figure 4C shown

[0310] ⑤ Comparative evaluation of the production capacity, stimulation parameters and physical properties of each fracturing stage.

Claims

1. A method for monitoring the production profile of an oil and gas well fracturing using a trace tracer, comprising the following steps: (1) Determine the type and model of tracer used in each fracturing stage of the target well; The types of trace tracers used in each fracturing stage of the target well include: oil phase tracers and / or gas phase tracers, and water phase tracers; (2) Determine the designed dosage, injection timing, and injection rate of trace tracer for each fracturing stage of the target well; Among them, the pumping timing of the trace tracer used in each fracturing stage of the target well is: The water phase tracer is injected throughout the fracturing process of this fracturing section during the pre-fluid stage and the sand-carrying fluid stage; When the fracture extension is not performed during the sand-carrying fluid stage of the fracturing process of the fracturing section, the oil phase tracer and / or the gas phase tracer are injected throughout the pre-fluid stage of the fracturing process of the fracturing section; When the fracture is extended in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and / or gas phase tracer is injected when sand is continuously added in the sand-carrying fluid stage during the fracturing process of the fracturing section and the injection is stopped when 2 / 3 of the sand-carrying fluid volume is injected; (3) During the fracturing construction of each fracturing section of the target well, the trace tracer injection operation is completed according to the determined trace tracer type and model, designed dosage, pumping timing and pumping speed; (4) After the completion of the fracturing construction of each fracturing stage in the target well, during the post-fracturing flowback and production process, the target well sampling operation shall be carried out according to the designed sampling system; (5) Testing each sample obtained from the target well sampling operation; determining the type and content of the trace tracer contained in each sample; (6) Determine the production profile of each fracturing stage of the target well based on the type and content of the trace tracer contained in each sample, as well as the output data during post-fracturing flowback and production; Wherein, in step (2), when determining the pumping timing of the trace tracer used in each fracturing section of the target well, when a fracturing section of the target well is temporarily plugged and fractured during the fracturing process, the pumping timing of the trace tracer used in the fracturing section of the target well is: The water phase tracer is injected in each pre-fluid stage and each sand-carrying fluid stage of the fracturing process of the fracturing section; When no fracture extension is performed in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and / or the gas phase tracer are respectively injected in each pre-fluid stage during the fracturing process of the fracturing section; When fracture extension is performed in the sand-carrying fluid stage during the fracturing process of the fracturing section, the oil phase tracer and / or gas phase tracer are respectively injected in each sand-carrying fluid stage during the fracturing process of the fracturing section.

2. The method according to claim 1, wherein The designed dosage of the aqueous phase tracer is calculated according to the following formula (1): A1 = a·μ1·MDL1·V p ·e1 expression(1) In formula (1), A1 is the designed dosage of water phase tracer, unit is kg; α is the coefficient of variation of permeability, unit is dimensionless; μ1 is the guarantee factor, unit is dimensionless, and the value is 2-5; MDL1 is the minimum detection limit of the aqueous phase tracer concentration detection instrument, unit is g / mL; V p The sum of the designed usage of the pre-fluid and the designed usage of the sand-carrying fluid for the target well in the fracturing section, unit: m 3 ; ε1 is the unit conversion coefficient.

3. The method according to claim 1, wherein The designed dosage of the gas phase tracer is calculated according to the following formula (2): A2 = α·μ2·MDL2·Q q ·T·ε2 Equation (2) In formula (2), A2 is the design dosage of gas phase tracer, unit is L; α is the permeability variation coefficient, unit is dimensionless; μ2 is the guarantee coefficient, unit is dimensionless, and the value is 2-5; MDL2 is the minimum detection limit of the gas phase tracer concentration detection instrument, unit is dimensionless; Q q The predicted daily gas production of the target well in this fracturing section, unit: m 3 / d; T is the monitoring time, unit is d; ε2 is the unit conversion coefficient.

4. The method according to claim 1, wherein The designed dosage of the oil phase tracer is calculated according to the following formula (3): A3= a·μ3·MDL3·Q L ·T·ε3 formula(3) In formula (3), A3 is the design dosage of oil phase tracer, unit is kg; α is the permeability variation coefficient, unit is dimensionless; μ3 is the guarantee factor, unit is dimensionless, and the value ranges from 2 to 5; MDL3 is the minimum detection limit of the oil phase tracer concentration detection instrument, unit is dimensionless; Q L is the predicted daily oil production of the target well in the fracturing section, in t / d; T is the monitoring time, in d; ε3 is the unit conversion coefficient.

5. The method according to claim 1, wherein During the sampling operation, gas sampling is carried out in the following manner: The gas is introduced into a sampling container containing a solid adsorbent so that the gas passes through the solid adsorbent and is discharged from the sampling container. After the gas is introduced for a specific time, the gas introduction is stopped and the sampling container is sealed to complete the sampling; wherein, the solid adsorbent can adsorb the gas phase tracer in the gas.

6. The method according to claim 5, wherein: The specific time for the gas to be introduced is 1 hour to 2 hours.

7. The method according to claim 1, wherein The method further comprises: After completing the fracturing construction of each fracturing section in the target well, during the post-fracturing flowback and production process, sampling operations are carried out at the target well's adjacent wells according to the designed sampling system; each sample obtained from the sampling operation at the target well's adjacent wells is tested to determine the type and content of the trace tracer contained in each sample, thereby judging the inter-well communication between the target well and the adjacent wells.

8. The method according to claim 1, wherein In the process of determining the type and content of the trace tracer contained in each sample, the type and content of the oil phase tracer can be determined using an inductively coupled plasma mass spectrometer.

9. The method according to claim 1, wherein: In the process of determining the type and content of the trace tracer contained in each sample, the type and content of the aqueous phase tracer can be determined using an inductively coupled plasma mass spectrometer.

10. The method according to claim 1, wherein The trace tracer is a nano-particle trace tracer with ultra-low surface and interfacial tension characteristics; wherein the ultra-low surface and interfacial tension characteristics refer to the trace tracer having a surface tension of less than 2×10 -2 Ultra-low interfacial tension of mN / m; The tracer was ultrasonically agitated before injection.

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