A method for gas kick control by integrating shut-in and absorption

Abstract

This application discloses an integrated gas invasion control method that combines inhibition and absorption, applied to wellbores experiencing gas invasion. The method includes the following steps: constructing a composite slurry column system in the wellbore, comprising, from bottom to top, a gas-intake slug and a gas-enhancing slug; the gas-intake slug converts free gas into a solid-phase adsorbed state or a liquid-phase dissolved state by adding gas-intake material to the drilling fluid, thereby reducing the gas volume in situ within the wellbore; the gas-enhancing slug triggers viscosity enhancement when residual gas enters by adding a gas-responsive material to the drilling fluid, increasing fluid resistance and mitigating gas slippage. This application achieves a synergistic gas control effect through a segmented composite slurry column system, first reducing gas volume through absorption and then increasing viscosity and reducing gas flow rate, enabling early proactive intervention in gas invasion, avoiding fluid instability and gas channeling risks, and improving well control success rate.

Description

Technical Field

[0001] This application relates to the field of oil drilling and production safety, and in particular to an integrated method for controlling gas intrusion by blocking and absorbing gas. Background Technology

[0002] With the intensified exploration and development of deep, ultra-deep, and unconventional oil and gas resources, the formation pressure systems encountered during drilling are becoming increasingly complex, with well-developed fluid intrusion channels such as formation micropores and fractures. During drilling, high-pressure gas is highly susceptible to intrusion into the wellbore through these formation channels. Due to the gas's extremely high compressibility and expansibility, its volume expands rapidly during its ascent, causing a rapid decrease in the wellbore fluid column pressure. Simultaneously, the gas diffuses extremely quickly, leaving a narrow window for emergency response, which can easily escalate into a blowout.

[0003] Currently, safety control measures after gas intrusion mainly include high-viscosity gas stagnation plugging, choke well control, or direct pumping of heavy mud for well control. However, high-viscosity gas stagnation plugging has problems such as complex preparation, difficulty in surface pumping, and high-temperature viscosity loss downhole. Choke well control is a passive response after gas reaches the shallow layer, lacking early active intervention for downhole gas. When using heavy mud for well control, due to the significant density difference between the upper heavy mud and the intruding gas and light mud below, Rayleigh-Taylor fluid instability is very likely to occur. The high-density weighting material settles rapidly under gravity, penetrating the light fluid interface, causing gas channeling, and preventing the heavy mud from establishing effective hydrostatic pressure.

[0004] In summary, existing gas invasion control methods are passive and simplistic, the interface of heavy slurry sealing is prone to instability, and there is a lack of early proactive intervention and in-situ consumption of downhole gas. Therefore, a new technical solution is needed to achieve proactive control of invading gas, improve gas invasion prevention and control capabilities, and increase well kill success rate. Summary of the Invention

[0005] This application provides an integrated gas invasion control method that combines inhibition and absorption. By constructing a composite slurry column system within the wellbore—characterized by "lower section reducing gas intake and upper section increasing viscosity upon encountering gas"—it achieves in-situ active consumption and high-viscosity inhibition and plugging of invading gas. Compared to traditional passive throttling or heavy slurry well control, this application avoids the risks of fluid instability and gas channeling caused by density differences, enabling early active intervention in gas invasion and thus improving the ability to control gas invasion risks and the success rate of well control.

[0006] This application provides an integrated gas intrusion control method that combines blocking and absorption, applied to wellbores experiencing gas intrusion, comprising the following steps: A composite slurry column system is constructed in the wellbore, the composite slurry column system comprising, from bottom to top, an intake slug and a gas-contaminated viscosity slug. The gas-absorbing plug converts free gas into solid-phase adsorbed state or liquid-phase dissolved state by adding gas-absorbing material to the drilling fluid, thereby reducing the gas volume in the wellbore in situ. The gas-responsive thickening slug increases viscosity by adding a gas-responsive material to the drilling fluid. When residual gas enters, it triggers thickening, increases fluid resistance, and slows down gas phase slippage.

[0007] Optionally, the gas-absorbing material includes a highly adsorbent or reactive material, which is selected from one or more of microencapsulated metal-organic framework materials and special organic amine gas absorbents; the special organic amine gas absorbent includes one or more mixtures of methyldiethanolamine, monoethanolamine, and diethanolamine.

[0008] Optionally, the gas-responsive material includes anionic polymerized triblock copolymers.

[0009] Optionally, the method further includes the following steps: adding a nano-blocking material to the composite slurry column system, wherein the nano-blocking material is used to block gas intrusion channels in the formation under positive pressure differential; the nano-blocking material is selected from one or more of surface-modified superhydrophilic nano-silica, nano-alumina, or nano-calcium carbonate, and its particle size distribution is 10-100 nm.

[0010] Optionally, the design length of the gas-injecting slug is determined by the following steps: calculating the expected total gas intrusion mass within the expected control operation time window, wherein the expected total gas intrusion mass includes the initial intrusion mass calculated based on the surface fluid level increment and the mass of gas continuously intruded into the formation during the operation; and determining the coupling relationship between the gas-injecting slug length and the material addition concentration based on the effective gas intake per unit mass of the gas-injecting material under bottom hole conditions, the gas-liquid dynamic contact efficiency coefficient, and the wellbore geometric parameters.

[0011] Optionally, the expected total gas intrusion mass is calculated using the following formula: ; in, The expected total gas intrusion mass is in kg; The atmospheric pressure at ground level is Pa. Let be the initial volume increment of the ground-level circulating pool, in m³; The molar mass of the intruding gas is expressed in kg / mol. The gas compressibility factor under standard ground operating conditions is dimensionless. Here is the universal gas constant, J / (mol·K); The ground temperature is constant, K; To determine the initial recovery slope of casing pressure during well shut-in ( The formation gas continuous mass intrusion rate, kg / s, is calculated by inversion using the wellbore gas-liquid two-phase flow model. s represents the expected control operation time window for implementing well control measures.

[0012] Optionally, the coupling relationship between the length of the intake septum plug and the material concentration is determined according to the following formula: ; In the formula, The design length of the intake septum plug is in meters (m). The concentration of the getter material in the getter septum is expressed in kg / m³. The inner diameter of the open-hole shaft or casing, in meters (m). The outer diameter of the center drill string, in meters; The effective air intake per unit mass of the air-absorbing material under bottom hole conditions, expressed in kg / kg. The gas-liquid dynamic contact efficiency coefficient ( The value ranges from 0.35 to 0.75.

[0013] Optionally, the design length of the gas-tightening slug should at least meet the time response criterion: the average slippage and upward movement time of the bubble within the gas-tightening slug should be greater than the complete thickening response time of the gas-responsive material.

[0014] Optionally, the minimum length of the gas-viscosifying slug is determined according to the following formula: ; In the formula, The design length of the gas-viscosified slug is given in meters. Let m be the minimum length of the gas-viscosified slug. The mean velocity of residual gas in the slug-based slurry is m / s; The time required for the material to fully thicken in response, as determined in indoor experiments, is expressed in seconds.

[0015] Optionally, the upper limit of the length of the intake septum plug satisfies: ; In the formula, The upper limit of the intake septum length, in meters; The sum of the lengths of the two sections of the plug, in meters; When the required intake slug length for the expected total gas intrusion mass exceeds the upper limit, the excess gas is allowed to move upward and is blocked by the gas-viscous slug.

[0016] This application has at least the following advantages: (1) By consuming part of the invading gas in situ through the intake sluice plug, the basis for gas phase expansion is greatly reduced, and early active intervention in gas invasion is achieved. The highly adsorbent or reactive material in the intake sluice plug can convert free gas into solid-phase adsorbed state or liquid-phase dissolved state, significantly reducing the gas phase volume in the wellbore, inhibiting gas phase expansion, and fundamentally reducing the risk of gas invasion.

[0017] (2) When the residual gas bubbles rise into the gas-tightening slug, they are blocked by the rapidly increasing high viscosity liquid, which effectively slows down the rising speed of the gas. The gas-responsive material in the gas-tightening slug triggers thickening when the gas enters, and the viscosity of the system increases rapidly, which increases the fluid resistance and slows down the rising speed of the residual gas phase, thus buying time for subsequent treatment.

[0018] (3) When the pressure drop generated by the upper slug restores the bottom of the well to an over-equilibrium state, the nano-plugging material or thickening product is squeezed into the gas-invaded formation under the drive of positive pressure differential, forming a dense filter cake isolation layer, cutting off the continuous gas intrusion channel. The nano-plugging material has a small particle size and can enter the formation micropores and fractures. Under the drive of positive pressure differential, it is forcibly squeezed into the gas-invaded formation, forming a dense filter cake isolation layer, physically blocking the gas intrusion channel, and cutting off the continuous gas intrusion from the source.

[0019] (4) It avoids the risks of fluid instability and gas channeling caused by density differences, and improves the ability to control gas invasion risks and the success rate of well control. This application achieves the synergistic gas control effect of "first absorbing and reducing volume, then increasing viscosity and reducing speed" by constructing a segmented composite mud column system. It avoids the "Rayleigh-Taylor" fluid instability phenomenon caused by the significant density difference between the upper heavy mud and the invading gas and light mud below in traditional heavy mud well control, effectively avoids the risk of gas channeling, and significantly improves the success rate of well control.

[0020] (5) This method can be applied to three working conditions: drilling control, gas blockage during drilling stoppage, and well control operations, and has wide applicability. Drilling control is suitable for drilling while preventing gas intrusion when the target layer or a high-risk gas intrusion layer is encountered; gas blockage during drilling stoppage is suitable for gas intrusion blockage during drilling stoppage conditions such as tripping in and out of the well and logging; well control operations are suitable for well control when there is no drill string in the wellbore and an empty well is formed. This method covers different working conditions of gas intrusion control and has strong practicality and promotion value. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the steps of an integrated gas intrusion control method that combines blocking and absorption in this embodiment. Figure 2 This is a schematic diagram showing the sequence of action of the intake plug and the gas-contaminated viscosity-increasing plug in this embodiment; Figure 3 This is a schematic diagram illustrating the implementation of drilling control in this embodiment; Figure 4This is a schematic diagram illustrating the implementation of the drilling stop gas blockage in this embodiment; Figure 5 This is a schematic diagram illustrating the implementation of the well control operation in this embodiment.

[0022] Attached reference numerals: 1. Intake plug; 2. Gas-contaminated plug; 3. Invading gas; 4. Center drill string; 5. Casing; 6. Annular flow channel; 7. Wellbore; 8. Formation gas intrusion channel. Detailed Implementation

[0023] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the scope of the present application.

[0024] It should be noted that the technical terms in the following embodiments are defined as follows: A gas-intake slug is a drilling fluid slug that converts free gas into a solid-phase adsorbed state or a liquid-phase dissolved state by adding highly adsorbent or reactive materials to the drilling fluid.

[0025] Gas-responsive slugs are drilling fluid slugs that are thickened when gas enters them by adding gas-responsive materials to the drilling fluid.

[0026] The composite slurry column system refers to a segmented drilling fluid system consisting of an air intake slug and an air-enhancing slug.

[0027] Please refer to Figure 1 As shown, this application provides an integrated gas intrusion control method that combines blocking and absorption, applied to wellbore 7 where gas intrusion occurs (e.g., Figure 3 (As shown), including the following steps: Step S1: Construct a composite slurry column system in wellbore 7. The composite slurry column system, from bottom to top, includes an intake slug 1 and a gas-tightening slug 2 (e.g., ...). Figure 2 (As shown).

[0028] Step S2: The gas-suction plug 1 converts free gas into solid-phase adsorbed state or liquid-phase dissolved state by adding gas-suction material to the drilling fluid, thereby reducing the gas volume in the wellbore 7 in situ.

[0029] Step S3, Gas-Resistant Viscosity Slug 2: By adding a gas-responsive material to the drilling fluid, viscosity is triggered when residual gas enters, increasing fluid resistance and slowing down gas phase slippage.

[0030] In this embodiment, a segmented composite slurry column system is employed to achieve a synergistic gas control effect of "first reducing volume through absorption, then increasing viscosity and slowing down." The intake sluice plug 1, located in the lower segment, directly contacts the intruding gas 3, reducing the gas phase volume in situ through physical adsorption or chemical absorption. The gas-enhancing sluice plug 2, located in the upper middle segment, triggers viscosity enhancement when residual gas rises, increasing fluid resistance and slowing the gas's upward velocity. This segmented layout ensures the efficient operation of each functional sluice plug, avoiding the problem of premature gas encapsulation by high-viscosity fluid leading to adsorption failure.

[0031] Each step is explained in detail below.

[0032] Step S1: Construct a composite slurry column system in the wellbore 7. The composite slurry column system includes, from bottom to top, an air intake plug 1 and an air-contaminated slurry plug 2.

[0033] Figure 2 This is a schematic diagram showing the sequence of action of the intake plug 1 and the gas-contaminated viscosity-increasing plug 2 in this embodiment; Figure 3 This is a schematic diagram illustrating the implementation of drilling control in this embodiment. Figure 3 The diagram mainly shows the process of pumping the composite slurry column system into the well through the central drill string 4, spraying it out from the bottom hole of the drill bit, and then returning upwards along the annular flow channel 6. It also shows the process of pumping in the air intake plug 1 and the air-enhancing slurry plug 2, as well as the effect after entering the annular flow channel 6, which is a dynamic and continuous circulation process.

[0034] Please refer to Figure 2 and Figure 3 As shown in this embodiment, it should be noted that when gas invasion occurs, an integrated slurry column system that combines blocking and absorption is constructed in the wellbore 7 to achieve in-situ intervention, migration control, and leakage channel sealing of the invading gas 3. To ensure the efficient operation of each function and avoid premature encapsulation of gas by high-viscosity fluid leading to adsorption failure, the composite slurry column system is divided into upper and lower parts. The first part is the gas-absorbing slug 1 located in the lower section, whose main function is to contact the invading gas 3 and reduce the amount of invading gas 3 through in-situ absorption, i.e., reduction. The second part is the gas-enhancing slug 2 located in the upper middle section, adjacent to it, whose main function is to increase fluid resistance, slow down the slippage of residual gas phase, and seal the formation pressure difference under static conditions.

[0035] Step S2: The gas-suction plug 1 converts free gas into solid-phase adsorbed state or liquid-phase dissolved state by adding gas-suction material to the drilling fluid, thereby reducing the gas volume in the wellbore 7 in situ. Please refer to Figure 2 and Figure 3As shown in this embodiment, it should be noted that the function of the gas-getting plug 1 is to directly contact and consume the intruding gas 3. By adding getter material to the drilling fluid, the free gas is converted into a solid-phase adsorbed state or a liquid-phase dissolved state, thereby reducing the gas phase volume in the wellbore 7 in situ and suppressing gas phase expansion. The getter material includes highly adsorbent or reactive materials, which can be selected from microencapsulated metal-organic framework materials (MOFs) or special organic amine gas absorbents. Specifically, special organic amine gas absorbents can be, but are not limited to, one or more mixtures of methyldiethanolamine (MDEA), monoethanolamine (MEA), and diethanolamine (DEA). Microencapsulated metal-organic framework materials (MOFs) physically adsorb gas molecules through their high specific surface area and pore structure, resulting in a large adsorption capacity; special organic amine absorbents absorb acidic gases (such as CO2 and H2S) through chemical reactions, resulting in a fast absorption rate.

[0036] Formation gas invasion is characterized by dynamic and continuous intrusion. To ensure sufficient slug capacity, it is first necessary to calculate the expected total gas invasion mass within the anticipated control operation time window. The anticipated control operation time window needs to be determined comprehensively based on the target well depth, drilling rate, circulation rate, tripping time, and kill fluid preparation cycle. Under conventional or deep well operation conditions, the anticipated operation time window is typically preset to 6–48 hours. For example, the normal drilling time window is approximately 12 hours, and the tripping time is approximately 48 hours. The specific time can be determined according to the drilling plan. This expected total gas invasion mass includes the initial invasion mass calculated based on the increase in surface fluid level, as well as the mass of gas continuously infiltrating the formation during the operation. The expected total gas invasion mass is calculated using the following formula: ; In the formula, The expected total gas intrusion mass is in kg; The atmospheric pressure at ground level is Pa. Let be the initial volume increment of the ground-level circulating pool, in m³; The molar mass of the intruding gas is expressed in kg / mol. The gas compressibility factor under standard ground operating conditions is dimensionless. Here is the universal gas constant, J / (mol·K); The ground temperature is constant, K; To determine the initial recovery slope of casing pressure during well shut-in ( The formation gas continuous mass intrusion rate, kg / s, was calculated by inversion using a wellbore gas-liquid two-phase flow model. The expected control operation time window for well control measures is s. Due to continuous formation gas intrusion, the casing pressure gauge reading on the surface will change after emergency well shut-in; data can be recorded on-site using instruments. Input into multiphase flow software can be reversed .

[0037] It should be noted that, under optimal conditions, the intake slug 1 must be able to completely absorb the aforementioned gas intrusion. Therefore, based on the effective gas intake per unit mass of the intake material under bottom hole conditions, the gas-liquid dynamic contact efficiency coefficient, and the wellbore geometric parameters, the coupling relationship between the design length of the intake slug 1 and the material concentration is determined. The coupling relationship between the length of the intake slug 1 and the material concentration is determined by the following formula: ; In the formula, The design length of the intake section plug 1 is in meters (m). The concentration of the getter material in the getter slug is expressed in kg / m³. For example, for microencapsulated MOFs, this concentration refers to the total mass of microcapsules added per unit volume of drilling fluid. The inner diameter of the open-hole shaft or casing, in meters (m). The outer diameter of the center drill string, in meters; The effective air intake per unit mass of the air-absorbing material under bottom hole conditions, expressed in kg / kg. The gas-liquid dynamic contact efficiency coefficient ( Gas-liquid dynamic contact efficiency coefficient The coefficient comprehensively characterizes the limitations of gas intrusion rate, fluid displacement, and wellbore trajectory on the absorption response. It is calibrated by measuring the ratio of actual gas absorption to static limit absorption under set dynamic conditions through multiphase flow tubing simulation experiments, or by interpolation from an empirical database. The value is usually taken as 0.35~0.75.

[0038] The concentration range of the getter material is determined by the dual criteria of "functional compliance" and "system compatibility". The upper limit of the concentration is based on the premise that its addition will not cause an abnormal surge in drilling fluid viscosity or damage the original rheological properties; the lower limit of the concentration is determined by the scale of gas intrusion and the required absorption rate under the corresponding operating conditions. In this embodiment, the preferred concentration of the getter material is 0.5% to 5.0% (mass fraction). This concentration range can balance the requirements for high-intensity gas intrusion absorption with wellbore fluid stability. The specific optimized value can be obtained through laboratory experiments based on the expected gas intrusion intensity of the target formation.

[0039] Step S3, Gas-Resistant Viscosity Slug 2: By adding a gas-responsive material to the drilling fluid, viscosity is triggered when residual gas enters, increasing fluid resistance and slowing down gas phase slippage.

[0040] Please refer to Figure 2 and Figure 3As shown in this embodiment, it should be noted that when gas intrusion continues and the gas ingress plug 1 is insufficient to absorb all the intruding gas 3, or when the length and concentration of the gas ingress plug 1 reach their upper limits but are still insufficient to absorb all the intruding gas 3 in the wellbore 7, the intruding gas 3 will continue to move upward. The upper limit of the concentration of the gas ingress plug 1 is determined based on solubility or compatibility, while the upper limit of the length needs to be determined based on the relative relationship between the gas ingress plug 1 and the gas-contaminated viscous plug 2. For example, before actual operation, the maximum dosage of the material to be added in the wellbore fluid environment is obtained through a high-temperature, high-pressure rheometer and static / dynamic compatibility experiments, and this is used as the upper limit of the concentration. (For example, the upper limit of the concentration of microencapsulated MOFs material is determined by the compatibility between the material and the drilling fluid base, ensuring that the addition does not cause an abnormal surge in drilling fluid viscosity or damage to the original rheological properties.)

[0041] In some embodiments, the core function of the gas-responsive thickening slug 2 is to slow down the slippage and ascent of residual gas phase. This thickening is triggered when intruding gas 3 enters the drilling fluid by adding a gas-responsive material. The gas-responsive material can be anionic polymerized triblock copolymer SEBS. SEBS is a gas-responsive thickening polymer; when intruding gas 3 enters, the conformation of the SEBS molecular chains changes, intermolecular interactions are enhanced, leading to a rapid increase in the system viscosity.

[0042] To ensure the effective functioning of the gas-induced viscosity-enhancing slug 2, its design length must comprehensively consider both time response and static pressure control criteria. As an example, the design length of the gas-induced viscosity-enhancing slug 2 is determined based on the gas slippage time and material reaction time. Specifically: First, based on the time response criterion, to ensure sufficient time for the gas to trigger the viscosity-enhancing reaction of the material, the initial design length of the gas-induced viscosity-enhancing slug 2 must satisfy the requirement that the average slippage and upward movement time of the bubble within it is greater than the complete viscosity-enhancing response time of the gas-responsive material. Its length is calculated as shown in the formula: ; In the formula, The design length of the gas-viscosifying slug 2 is in meters. Let m be the minimum length of the gas-viscosified plug 2; The mean velocity of residual gas in the slug-based slurry is m / s; The time required for the material to fully thicken in indoor experiments is s; this time is obtained by dynamic testing using a high-temperature, high-pressure rheometer under conditions of equal gas mixing.

[0043] To ensure the optimal function of the composite slug system, the dosage (concentration range and slug length) of the getter material and thickener (i.e., gas-responsive material) must be rationally optimized, and its total design length... The sum of the independently designed lengths of the two plug sections, i.e. This achieves the optimal comprehensive gas control effect of "first reducing volume, then increasing viscosity and slowing down". Therefore, the upper limit of the length of the intake septum plug 1 is shown in formula (4): ; In the formula, The upper limit of the length of the intake section plug 1, in meters; Let m be the total length of the two sections of the plug.

[0044] In some embodiments, the concentration range of the gas-responsive material is also determined by the dual criteria of "functional compliance" and "system compatibility". In this embodiment, the concentration of the gas-responsive material is preferably 1.0% to 3.0% (mass fraction). This concentration range ensures that the material produces sufficient thickening effect upon contact with gas, without affecting the pumpability of the slug.

[0045] In an embodiment, the control method of this application further includes the following steps: Step S4: Add nano-sealing material to the composite slurry column system to seal the formation gas intrusion channels.

[0046] In this embodiment, it should be noted that nano-blocking materials are added to the composite slurry column system to block formation gas intrusion channels. The nano-blocking materials can be selected from one or more of surface-modified superhydrophilic nano-silica, nano-alumina, and nano-calcium carbonate, with a preferred particle size distribution of 10–100 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, and 100 nm. These nano-blocking materials have small particle sizes, enabling them to enter formation gas intrusion channels 8 (e.g., Figure 3 (As shown) For example, formation micropores and fractures; superhydrophilic surface modification enhances the dispersibility of nano-plugging materials in water-based drilling fluids and their adsorption capacity on formation pore walls.

[0047] This composite grout column system can be applied in the following three ways depending on the working conditions: Application Method 1: Drilling-while-drilling control.

[0048] Please refer to Figure 3 As shown, Figure 3The arrows indicate the injection direction and flow direction of the composite slurry column system, flowing from the central drill string 4 to the annular channels 6 on both sides. When encountering the target layer or a high-risk gas invasion layer, the gas-enhancing slug 2 is injected first from top to bottom into the central drill string 4, followed by the gas-intake slug 1. The two slugs then circulate alternately into the wellbore 7. When the composite slurry column system returns to the annular channel 6 after being ejected from the drill bit, it forms the lower gas-intake slug 1 and the upper gas-enhancing slug 2. The ratio of gas-intake material to gas-responsive material is adjusted to avoid affecting the rheological properties of conventional drilling fluid, forming a gas invasion prevention system during drilling, achieving simultaneous prevention and dynamic suppression of gas invasion during drilling. The slug lengths can be equal, equivalent to the minimum length of the gas-enhancing slug 2. This alternating injection method ensures that the composite slurry column system of gas-intake slug 1 and gas-enhancing slug 2 is always present in the wellbore 7, enabling real-time control of potential gas invasion during drilling.

[0049] Application Method 2: Drilling Stop Gas Blockage.

[0050] Please refer to Figure 4 As shown, the main demonstration is the process of the composite slurry column system being returned into the annular flow channel 6 to cover the leaking gas layer and then stuck in the annular flow channel 6 as a static plug. The injection process is the same as that of the drilling control and will not be shown here. During drilling stop conditions such as tripping in and out of the well and logging, since the gas-absorbing plug 1 is in a static state, the gas-contaminated viscous plug 2 is located above the gas-absorbing plug 1, and the material addition ratio is based on the solubility as the upper limit. This composite slurry column system can be pumped alone to replace the conventional gas stagnation plug, or it can be used as a supplement to the conventional gas stagnation plug and mixed with it. When it can completely absorb the invading gas 3, the length of the gas-absorbing plug 1 needs to reach the length that can absorb all the gas, and the gas-contaminated viscous plug 2 can be equal to the minimum length; when it cannot completely absorb the gas 3, the gas-contaminated viscous plug 2 needs to exceed the minimum length, such as 1.5 to 2.0 times. At this time, in order to meet the hydrostatic pressure balance, the necessary length of the gas-absorbing plug 1 needs to be calculated by reverse solution through the pressure balance model. The calculation formula is shown in equation (5): ; In the formula: The design length of the intake section plug 1 is in meters (m). The target wellbore pressure required to stabilize the formation, Pa; The total depth of the wellbore is in meters (m). The length of the extended gas-contaminated septum plug 2 is in meters (m). The density of the intake plug 1 is kg / m³; The density of plug 2, which becomes viscous upon contact with air, is kg / m³. The density of conventional drilling fluid in the wellbore, in kg / m³; The acceleration due to gravity is taken as 9.8 m / s².

[0051] Application Method 3: Well Control Operations.

[0052] Please refer to Figure 5 As shown, when a well is formed without a central drill string 4 in the wellbore 7 and a well kill operation is performed, an integrated gas-absorbing and gas-receiving material (i.e., gas-absorbing material and gas-responding material) is added to the kill fluid and pumped into the wellbore. First, the gas-absorbing slug 1 is injected, followed by the gas-responding viscosity-enhancing slug 2, and then injected into the wellbore 7 alternately. The slug lengths can be equal, equal to the minimum length of the gas-responding viscosity-enhancing slug 2, and an appropriate amount of sealing material (i.e., nano-sealing material) is added. This method is suitable for well kill operations when a wellbore is formed without a central drill string 4 in the wellbore 7, effectively controlling the gas intrusion situation and improving the well kill success rate.

[0053] The implementation principle of this embodiment is as follows: By constructing a composite slurry column system of "gas intake reduction and viscosity enhancement and blockage" from bottom to top in the wellbore 7, and adding nano-sealing materials to dynamically block the formation gas invasion channel 8, active in-situ intervention and source-coordinated management of the invading gas 3 are achieved, thereby improving the ability to control gas invasion risks and the success rate of well control. Specifically: some of the invading gas 3 is consumed in situ by the gas intake sluice plug 1 in the lower part, greatly reducing the basis of gas phase expansion; when the residual gas bubbles rise into the gas-enhancing sluice plug 2 in the upper section, they are blocked by the rapidly increasing high-viscosity liquid. When the pressure drop generated by the upper sluice plug restores the bottom of the well to an over-equilibrium state, the appropriate proportion of nano-sealing materials or viscosity enhancement products in the system are forcibly squeezed into the gas-invading formation under the positive pressure difference, forming a single layer or multiple layers of adsorption on the formation pore wall, gradually accumulating to form a dense filter cake isolation layer, physically blocking the gas invasion channel and cutting off the continuous gas invasion channel. Compared to traditional passive throttling or heavy slurry killing techniques, this embodiment avoids the risks of fluid instability and gas channeling caused by density differences, thereby improving the ability to control gas intrusion risks and the success rate of well killing.

[0054] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for controlling gas intrusion by integrating inhibition and absorption, applied to wellbores experiencing gas intrusion, characterized in that, Includes the following steps: A composite slurry column system is constructed in the wellbore, the composite slurry column system comprising, from bottom to top, an intake slug and a gas-contaminated viscosity slug. The gas-absorbing plug converts free gas into solid-phase adsorbed state or liquid-phase dissolved state by adding gas-absorbing material to the drilling fluid, thereby reducing the gas volume in the wellbore in situ. The gas-responsive thickening slug increases viscosity by adding a gas-responsive material to the drilling fluid. When residual gas enters, it triggers thickening, increases fluid resistance, and slows down gas phase slippage.

2. The control method according to claim 1, characterized in that, The gas-absorbing material includes highly adsorbent or reactive materials, which are selected from one or more of microencapsulated metal-organic framework materials and special organic amine gas absorbents. The special organic amine gas absorbent includes one or more of methyldiethanolamine, monoethanolamine, and diethanolamine.

3. The control method according to claim 1, characterized in that, The gas-responsive material comprises anionic polymerized triblock copolymers.

4. The control method according to claim 1, characterized in that, It also includes the following steps: A nano-blocking material is added to the composite slurry column system. The nano-blocking material is used to block gas intrusion channels in the formation under positive pressure differential. The nano-blocking material is selected from one or more of surface-modified superhydrophilic nano-silica, nano-alumina, or nano-calcium carbonate, and its particle size distribution is 10-100 nm.

5. The control method according to claim 1, characterized in that, The design length of the intake section plug is determined through the following steps: Calculate the expected total gas intrusion mass within the expected control operation time window, wherein the expected total gas intrusion mass includes the initial intrusion mass calculated based on the increase in the surface liquid level and the mass of gas continuously intruding into the formation during the operation; Based on the effective gas intake per unit mass of the gas-absorbing material under bottom hole conditions, the gas-liquid dynamic contact efficiency coefficient, and wellbore geometric parameters, the coupling relationship between the gas-absorbing slug length and the material addition concentration is determined.

6. The control method according to claim 5, characterized in that, The expected total gas intrusion mass is calculated using the following formula: ； in, The expected total gas intrusion mass is in kg; The atmospheric pressure at ground level is Pa. Let be the initial volume increment of the ground-level circulating pool, in m³; The molar mass of the intruding gas is expressed in kg / mol. The gas compressibility factor under standard ground operating conditions is dimensionless. Here is the universal gas constant, J / (mol·K); The ground temperature is constant, K; To determine the initial recovery slope of casing pressure during well shut-in ( The formation gas continuous mass intrusion rate, kg / s, is calculated by inversion using the wellbore gas-liquid two-phase flow model. s represents the expected control operation time window for implementing well control measures.

7. The control method according to claim 6, characterized in that, The coupling relationship between the length of the intake septum plug and the material concentration is determined by the following formula: ； In the formula, The design length of the intake septum plug is in meters (m). The concentration of the getter material in the getter septum is expressed in kg / m³. The inner diameter of the open-hole shaft or casing, in meters (m). The outer diameter of the center drill string, in meters; The effective air intake per unit mass of the air-absorbing material under bottom hole conditions, expressed in kg / kg. The gas-liquid dynamic contact efficiency coefficient ( The value ranges from 0.35 to 0.

75.

8. The control method according to claim 3, characterized in that, The design length of the gas-tightening slug must at least meet the time response criterion: the average slippage and upward movement time of the bubble within the gas-tightening slug must be greater than the complete thickening response time of the gas-responsive material.

9. The control method according to claim 8, characterized in that, The minimum length of the gas-viscosifying slug is determined by the following formula: ； In the formula, The design length of the gas-viscosified slug is given in meters. Let m be the minimum length of the gas-viscosified slug. The mean velocity of residual gas in the slug-based slurry is m / s; The time required for the material to fully thicken in response, as determined in indoor experiments, is expressed in seconds.

10. The control method according to claim 9, characterized in that, The upper limit value of the length of the intake septum plug satisfies: ； In the formula, The upper limit of the intake septum length, in meters; The sum of the lengths of the two sections of the plug, in meters; When the required intake slug length for the expected total gas intrusion mass exceeds the upper limit, the excess gas is allowed to move upward and is blocked by the gas-viscous slug.

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