A well blowout control method based on wellhead methane adsorption

Abstract

The application provides a well blowout control method based on wellhead methane adsorption. In a key stage before well blowout, i.e. when overflow or well kick and other well control accidents occur, a high-density composite kill fluid is formed by compounding methane adsorption material with other necessary drilling fluid additives. Then, the composite kill fluid is injected into the wellbore through a special kill fluid injection device at a position 100-200 meters below the wellhead according to preset injection parameters. The method effectively suppresses the upward sliding of methane gas bubbles invading the wellbore by the high density of the kill fluid, and simultaneously absorbs the methane gas in the wellbore in real time by the methane adsorption material compounded therein. Through the dual action mechanism of density suppression and active adsorption, the method effectively controls the expansion of the gas column and the rise of the pressure in the early stage of gas invasion, thereby preventing the occurrence of well blowout or restraining the development of well blowout.

Description

Technical Field

[0001] The invention belongs to the technical field of blowout prevention in oil and gas drilling operations, and in particular relates to a blowout control method based on wellhead methane adsorption. Background Art

[0002] Wellbore safety and stability are crucial in drilling operations. In practice, gas intrusion is a common occurrence within the wellbore and a major factor contributing to safety incidents such as blowouts. Gas intrusion occurs when formation gases (such as methane molecules) enter the drilling fluid within the wellbore and rise with it during drilling. Methane, a major component of natural gas, has low density and high diffusivity, making it prone to accumulation within the wellbore, potentially leading to serious accidents such as blowouts. Encountering high-pressure gas formations is a common risk in oil and gas well drilling. When the drill bit penetrates a high-pressure gas formation, high-pressure gas rapidly intrudes into the wellbore, causing a sharp increase in wellbore pressure. If effective measures are not taken promptly, the gas will continue to propel the drilling fluid column above it outward with high momentum, potentially causing serious safety incidents such as kicks, uncontrolled blowouts, and even fires.

[0003] Traditional well control systems, centered around mechanical blowout preventers (BOPs) and drilling fluid density adjustment, are essentially passive, post-empty measures. BOP mechanical operation has a response delay of several seconds to tens of seconds, precious time enough for high-pressure gas to break through the fluid column and form a jet. While drilling fluid density adjustment can temporarily suppress gas intrusion, it cannot remove methane that has already entered the wellbore. Furthermore, in extreme operating conditions such as deepwater, ultra-high temperature, and high pressure, the narrow density window and the inability of the fluid column pressure gradient to match formation pressure often lead to a "no more adjustment" dilemma. This passive, "leak first, plug later" approach essentially postpones accident risks rather than eliminating them, and falls short of the "zero blowout" inherent safety philosophy of modern drilling. Therefore, there is an urgent need for new blowout control methods that can more proactively and rapidly intervene in the progression of gas intrusion, specifically effectively curbing blowouts at the critical point where gas approaches the wellhead. Summary of the Invention

[0004] In view of this, the present invention aims to propose a blowout control method based on wellhead methane adsorption to solve the technical problems of traditional well control methods such as passive remediation, delayed response, inability to remove methane gas that has invaded the wellbore, and suppression of gas column expansion and pressure rise in the early stage of gas invasion, which leads to the risk of blowout.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A blowout control method based on wellhead methane adsorption is provided. In the early stages of methane invasion, a high-density composite killing fluid is injected to achieve a dual mechanism of density suppression and active adsorption of methane gas molecules. The method comprises the following steps:

[0007] S1. Startup phase: Real-time monitoring of the methane concentration of the gas returning from the wellhead. When the methane concentration is ≥5%, the blowout control method is immediately started.

[0008] S2. Composite Kill Fluid Injection: Inject the composite kill fluid into the wellbore at a depth of 100-200 meters below the wellhead through coiled tubing or kill line to ensure full contact with the rising gas intrusion fluid; the composite kill fluid contains a methane adsorbent, a weighting agent, a dispersant, a fluid loss additive, a thickener, and water or a base fluid;

[0009] S3. Real-time monitoring and dynamic control of the injection process: During the injection of the composite killing fluid, the pressure, temperature, and methane gas concentration in the wellbore are monitored in real time, with a monitoring frequency of at least once per second. Based on the real-time monitoring data, the injection rate and / or injection pressure of the composite killing fluid are dynamically adjusted to maintain a stable flow pattern and uniform distribution of the killing fluid in the wellbore;

[0010] S4. Post-injection monitoring and effect confirmation: After the injection of the composite well-killing fluid is completed, the pressure changes in the wellbore are continuously monitored until the pressure change rate is less than ±0.1 MPa / minute and the continuous stability time exceeds 30 minutes, confirming that the blowout risk is effectively controlled.

[0011] Furthermore, the methane adsorption material is a hydrophobically modified 13X zeolite molecular sieve, a high specific surface area modified microporous activated carbon, and an organic metal framework material MOFs in a mass ratio of (10-12): (7-8): (2-3).

[0012] Furthermore, the hydrophobically modified 13X zeolite molecular sieve has a pore size of 9-10Å, a water contact angle greater than 130°, strong hydrophobicity, and a particle size of 1-5μm. It also has high framework rigidity and is resistant to high temperatures up to 200°C, salt, and shear. It is cost-effective and provides a basic adsorption capacity for methane adsorption in well killing fluids, ensuring system stability and cost control.

[0013] The pore size of high specific surface area modified microporous activated carbon is concentrated in the micropore range of less than 2 nm, with ultra-high specific surface area, water contact angle greater than 130°, strong hydrophobicity, particle size of 100-150μm, surface inertness, easy dispersion; the adsorption capacity per unit mass is the highest, with extremely high cost performance;

[0014] Organic metal frameworks (MOFs) have open metal sites and ultra-high specific surface area, and a small amount (<5%) can provide additional adsorption capacity in the high-pressure range of >5 MPa.

[0015] Furthermore, the weighting agent is selected from at least one of micronized hematite, micronized ilmenite, barite powder, and micro manganese ore powder; the dispersant is selected from at least one of lignin sulfonate and acrylic acid-sulfonate copolymer; the thickener is selected from at least one of xanthan gum, modified starch, modified cellulose, and hydroxypropyl guar gum; and the fluid loss additive is selected from at least one of polyanionic cellulose (PAC-R), hydrophobically modified nano-silica, and sulfonated asphalt.

[0016] Furthermore, the contents of the components in the composite well killing fluid are as follows, by mass percentage: methane adsorbent 18-25%, weighting agent 35-50%, dispersant 0.3-1.5%, thickener 0.8-2.0%, fluid loss additive 0.8-2.0%, and the balance water or base liquid;

[0017] The density of the composite well killing fluid is 2.0-2.5 g / cm³.

[0018] Furthermore, the composite well-killing fluid also contains, by mass percentage, 0.05-0.15% of a defoaming agent, 0.05-0.2% of a pH regulator, and 0-1% of a wetting agent; the defoaming agent is one of an organic silicon emulsion, a polyether-modified silicone oil, and a polysiloxane emulsion; the pH regulator is one of sodium hydroxide and magnesium oxide; and the wetting agent is one of ethoxylated alcohol, sulfomethyl ethyl glucoside, and polyether-modified silicone oil.

[0019] Furthermore, the total amount of the dispersant, thickener, fluid loss additive, defoamer, pH regulator and wetting agent added accounts for 2.5% to 3.5% of the total mass of the composite well killing fluid.

[0020] Furthermore, in step S2, the injection rate of the composite well-killing fluid is 0.5-3.0 m 3 / min, the injection pressure control range is 5-50 MPa, and does not exceed 80% of the formation fracture pressure. The single injection volume is 1.2-2.5 times the wellbore volume. During the injection process, the annular return velocity is ensured to be ≥0.8 m / s.

[0021] Furthermore, in step S3, dynamic adjustment adopts a closed-loop control algorithm: when the real-time monitored wellbore pressure fluctuation exceeds ±0.5 MPa, the temperature deviates from the base temperature by ±15°C (which may indicate abnormal downhole reaction or intensified gas invasion), the methane concentration is ≥3% or the methane content of the return fluid is ≥10% (volume fraction, indicating that gas invasion is not completely suppressed), the injection rate of the composite well killing fluid is automatically adjusted (0.5-3.0 m 3 / min) and pressure (5-50 MPa) to maintain a stable flow pattern in the wellbore.

[0022] Furthermore, the real-time monitoring data in steps S3 and S4 are synchronized to the control center via a wireless transmission system; the pressure monitoring equipment uses a high-precision sensor with an error of ≤±0.1% FS.

[0023] This invention utilizes high-performance methane adsorption materials to establish a "gas interception and reduction" barrier near the wellhead, constructing an innovative blowout control method. The core ideas of this method are: 1) at the critical moment before a blowout occurs, materials with high methane adsorption capacity are compounded with weighting agents and other well-killing fluid additives to form a high-density, multifunctional composite well-killing fluid; 2) at a distance of 100-200 meters from the wellhead, using specific well-killing fluid injection equipment, the composite well-killing fluid is injected into the wellbore according to pre-calculated injection parameters; 3) the high density of the well-killing fluid is used to suppress the continuously escaping and rising methane gas, while the high adsorption properties of the methane adsorption materials compounded in the well-killing fluid are simultaneously used to rapidly absorb the methane gas that has invaded the wellbore, achieving a dual-action mechanism of adsorption and suppression, thereby effectively controlling the blowout and avoiding the many risks and difficulties faced by traditional well control methods that require emergency treatment only after a blowout has occurred.

[0024] Compared with the prior art, the blowout control method based on wellhead methane adsorption described in the present invention has the following advantages:

[0025] (1) The blowout control method based on wellhead methane adsorption described in the present invention can break through the passive defense mode of traditional well control technology, realize active intervention in the early stage of gas invasion, and actively intervene in the (overflow / well kick stage) by injecting a composite well-killing fluid containing adsorption materials 100-200 meters below the wellhead. An "interception barrier" is established at the key link where the methane gas column approaches the wellhead, and the risk control node is advanced from "after the blowout occurs" to "early stage of gas invasion", avoiding the gas breaking through the liquid column to form a jet.

[0026] (2) The blowout control method based on wellhead methane adsorption described in the present invention integrates the dual mechanisms of "density suppression + active adsorption", which can not only suppress the slippage and rise of bubbles, but also adsorb dissolved and free methane molecules in real time, directly reduce the gas volume, and block the blowout chain reaction from the root. It is particularly suitable for deep water / ultra-high temperature and high pressure extreme working conditions where traditional methods "cannot adjust anything".

[0027] (3) The blowout control method based on wellhead methane adsorption described in the present invention includes three emergency prevention and control measures: precise wellhead intervention (injection in the key path of high-pressure gas invasion), material adaptability (hydrophobically modified zeolite (13X) and microporous activated carbon (MAC) still maintain high adsorption efficiency under high pressure / high salt environment), and compound system stability (addition of dispersants (lignin sulfonate, etc.) and thickeners (xanthan gum, etc.) to ensure uniform dispersion and long-term effect of adsorption materials). These measures can significantly reduce the probability of uncontrolled blowouts caused by BOP delay or density imbalance.

[0028] (4) The blowout control method based on wellhead methane adsorption described in the present invention has a simple process and can be directly implemented through existing well-killing fluid injection equipment without the need for new large-scale equipment; the material cost is low, adsorbents such as zeolite and activated carbon are mature in industrialization, and compound additives such as PAC-R fluid loss additive are all conventional reagents and are convenient and easy to obtain.

[0029] (5) The blowout control method based on wellhead methane adsorption described in the present invention can ensure personnel safety and reduce the escape emission of methane molecules, thereby complying with environmental protection regulations. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 Schematic diagram of the injection position of composite well-killing fluid. DETAILED DESCRIPTION

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Example 1

[0035] A blowout control method based on wellhead methane adsorption controls the initial stage of methane invasion by injecting a high-density composite killing fluid to achieve a dual mechanism of density suppression and active adsorption of methane gas molecules. The method specifically includes the following steps:

[0036] S1. Startup phase: Real-time monitoring of the methane concentration of the gas returning from the wellhead. When the concentration is ≥5%, the blowout control method is immediately started.

[0037] S2. Injection of composite killing fluid: Inject composite killing fluid at a depth of 100-200 meters below the wellhead through coiled tubing or killing pipeline. Figure 1 As shown, ensure that it is in full contact with the rising gas intrusion fluid;

[0038] The composite well killing fluid comprises, by mass percentage, 20% of methane adsorbent, 40% of weighting agent, 0.5% of dispersant, 1.2% of thickener, 1.2% of fluid loss additive, 0.075% of defoaming agent, 0.05% of pH regulator, and the balance of water;

[0039] Among them, the methane adsorption materials are hydrophobically modified 13X zeolite molecular sieve, high specific surface area modified microporous activated carbon, and organic metal framework material MOFs in a mass ratio of 10:7:3; the hydrophobically modified 13X zeolite molecular sieve has a pore size of about 10 Å, a water contact angle greater than 130°, and a particle size of 1-5 μm; the high specific surface area modified microporous activated carbon has a pore size of <2 nm, a water contact angle >130°, and a particle size of 100-150 μm; the organic metal framework MOFs has open metal sites and ultra-high specific surface area, and a small amount (<5%) can provide additional adsorption capacity in the high-pressure section of >5 MPa.

[0040] The weighting agent is barite powder, the dispersant is sodium lignin sulfonate, the thickener is xanthan gum, the fluid loss reducer is polyanionic cellulose, the defoaming agent is silicone emulsion, and the pH adjuster is sodium hydroxide.

[0041] The density of the composite killing fluid is 2.3g / cm³, and the injection displacement is dynamically controlled at 0.5-3.0 m 3 / min range (ensuring that the annular return velocity is ≥0.8 m / s), the injection pressure is 30 MPa (not exceeding 80% of the formation fracture pressure at the casing shoe), the single injection volume is 2.0 times the wellbore volume, and the gas content of the return fluid is monitored in real time to adjust the subsequent injection volume.

[0042] S3. Real-time monitoring and dynamic control of the injection process: During the injection of the composite killing fluid, high-precision sensors (Full Scale) with an error of ≤±0.1%FS monitor the wellbore pressure, temperature, and methane concentration every second. The data is synchronized to the control center via a wireless transmission system. A closed-loop control algorithm is used to dynamically adjust the injection displacement or pressure to ensure that the wellbore pressure fluctuation is ≤±0.5 MPa and the flow state is stable.

[0043] Dynamic adjustment uses a closed-loop control algorithm: when the real-time monitored wellbore pressure fluctuation exceeds ±0.5 MPa, the temperature deviates from the base temperature by ±15°C, the methane concentration is ≥3%, or the methane gas content of the return fluid is ≥10% by volume, the injection rate and pressure of the composite well-killing fluid are automatically adjusted to maintain a stable flow state in the wellbore.

[0044] S4. Post-injection monitoring and effect confirmation: After the injection of the composite well-killing fluid is completed, the wellbore pressure changes are continuously monitored (frequency ≥ 1 time / second). When the pressure change rate is less than ±0.1 MPa / minute and remains stable for more than 30 minutes, it is confirmed that the blowout risk has been eliminated.

[0045] Example 2

[0046] A blowout control method based on wellhead methane adsorption specifically comprises the following steps:

[0047] S1. Startup phase: Real-time monitoring of the methane concentration of the gas returning from the wellhead. When the concentration is ≥5%, the blowout control method is immediately started.

[0048] S2. Composite killing fluid injection: Inject composite killing fluid at a depth of 100-200 meters below the wellhead through coiled tubing or killing pipeline;

[0049] The composite well killing fluid comprises, by mass percentage, 21% of methane adsorbent, 45% of weighting agent, 1.0% of dispersant, 1.2% of thickener, 1.0% of fluid loss additive, 0.1% of defoaming agent, 0.1% of pH regulator, and the balance of water;

[0050] The methane adsorption materials are hydrophobically modified 13X zeolite molecular sieve, high specific surface area modified microporous activated carbon, and metal organic framework materials MOFs in a mass ratio of 11:8:2;

[0051] The weighting agent is micro manganese ore powder, the dispersant is AA / AMPS copolymer, the thickener is modified cellulose, the fluid loss additive is sulfonated asphalt, the defoamer is polyether modified silicone oil, and the pH adjuster is magnesium oxide.

[0052] The density of the composite killing fluid is 2.4g / cm³, and the injection displacement is dynamically controlled at 0.5-3.0 m 3 / min range (ensuring that the annular return velocity is ≥0.8 m / s), the injection pressure is 10 MPa (not exceeding 80% of the formation fracture pressure at the casing shoe), the single injection volume is 1.8 times the wellbore volume, and the gas content of the return fluid is monitored in real time to adjust the subsequent injection volume.

[0053] S3. Real-time monitoring and dynamic control of the injection process: During the injection of the composite killing fluid, high-precision sensors (Full Scale) with an error of ≤±0.1%FS monitor the wellbore pressure, temperature, and methane concentration every second. The data is synchronized to the control center via a wireless transmission system. A closed-loop control algorithm is used to dynamically adjust the injection displacement or pressure to ensure that the wellbore pressure fluctuation is ≤±0.5 MPa and the flow state is stable.

[0054] Dynamic adjustment uses a closed-loop control algorithm: when the real-time monitored wellbore pressure fluctuation exceeds ±0.5 MPa, the temperature deviates from the base temperature by ±15°C, the methane concentration is ≥3%, or the methane gas content of the return fluid is ≥10% by volume, the injection rate and pressure of the composite well-killing fluid are automatically adjusted to maintain a stable flow state in the wellbore.

[0055] S4. Post-injection monitoring and effect confirmation: After the injection of the composite well-killing fluid is completed, the wellbore pressure changes are continuously monitored (frequency ≥ 1 time / second). When the pressure change rate is less than ±0.1 MPa / minute and remains stable for more than 30 minutes, it is confirmed that the blowout risk has been eliminated.

[0056] Example 3

[0057] A blowout control method based on wellhead methane adsorption specifically comprises the following steps:

[0058] S1. Startup phase: Real-time monitoring of the methane concentration of the gas returning from the wellhead. When the concentration is ≥5%, the blowout control method is immediately started.

[0059] S2. Composite killing fluid injection: Inject composite killing fluid at a depth of 100-200 meters below the wellhead through coiled tubing or killing pipeline;

[0060] The composite well killing fluid comprises, by mass percentage, 20% methane adsorbent, 45% weighting agent, 0.6% dispersant, 1.0% thickener, 1.2% fluid loss additive, 0.12% defoamer, 0.05% pH regulator, 0.5% wetting agent, and the balance water;

[0061] The methane adsorption materials are hydrophobically modified 13X zeolite molecular sieve, high specific surface area modified microporous activated carbon, and metal organic framework materials MOFs in a mass ratio of 12:7:2;

[0062] The weighting agent is manganese ore powder (Mn3O4, density 4.8 g / cm³), the dispersant is AA / AMPS copolymer, the thickener is hydroxypropyl guar gum (HPG), the fluid loss additive is sulfonated asphalt, the defoamer is polysiloxane emulsion, the pH adjuster is sodium hydroxide, and the wetting agent is ethoxylated alcohol.

[0063] The density of the composite killing fluid is 2.5g / cm³, and the injection displacement is dynamically controlled at 0.5-3.0 m 3 / min range (ensuring that the annular return velocity is ≥0.8 m / s), the injection pressure is 50 MPa (not exceeding 80% of the formation fracture pressure at the casing shoe), the single injection volume is 2.5 times the wellbore volume, and the gas content of the return fluid is monitored in real time to adjust the subsequent injection volume.

[0064] S3. Real-time monitoring and dynamic control of the injection process: During the injection of the composite killing fluid, high-precision sensors (Full Scale) with an error of ≤±0.1%FS monitor the wellbore pressure, temperature, and methane concentration every second. The data is synchronized to the control center via a wireless transmission system. A closed-loop control algorithm is used to dynamically adjust the injection displacement or pressure to ensure that the wellbore pressure fluctuation is ≤±0.5 MPa and the flow state is stable.

[0065] Dynamic adjustment uses a closed-loop control algorithm: when the real-time monitored wellbore pressure fluctuation exceeds ±0.5 MPa, the temperature deviates from the base temperature by ±15°C, the methane concentration is ≥3%, or the methane gas content of the return fluid is ≥10% by volume, the injection rate and pressure of the composite well-killing fluid are automatically adjusted to maintain a stable flow state in the wellbore.

[0066] S4. Post-injection monitoring and effect confirmation: After the injection of the composite well-killing fluid is completed, the wellbore pressure changes are continuously monitored (frequency ≥ 1 time / second). When the pressure change rate is less than ±0.1 MPa / minute and remains stable for more than 30 minutes, it is confirmed that the blowout risk has been eliminated.

[0067] Experiment 1 Screening of methane adsorption materials

[0068] In order to screen materials with better methane molecule adsorption capacity, the following methane molecule adsorption performance studies were conducted:

[0069] Material A: The methane adsorption material is a hydrophobically modified 13X zeolite molecular sieve, a high specific surface area modified microporous activated carbon, and an organic metal framework material MOFs in a mass ratio of 10:7:3 (Example 1);

[0070] Material B: The methane adsorption material is a hydrophobically modified 13X zeolite molecular sieve, a high specific surface area modified microporous activated carbon, and an organic metal framework material MOFs in a mass ratio of 11:8:2 (Example 2);

[0071] Material C: The methane adsorption material is a hydrophobically modified 13X zeolite molecular sieve, a high specific surface area modified microporous activated carbon, and an organic metal framework material MOFs in a mass ratio of 12:7:2 (Example 3);

[0072] Material D: The methane adsorption material is a hydrophobically modified 13X zeolite molecular sieve, a high specific surface area modified microporous activated carbon, and an organic metal framework material MOFs in a mass ratio of 8:10:5;

[0073] Material E: Compared with Material A, the methane adsorption material removes the metal organic framework material MOFs and is composed of a hydrophobically modified 13X zeolite molecular sieve and a high specific surface area modified microporous activated carbon with a mass ratio of 10:7;

[0074] Material F: Compared with material A, the methane adsorption material removes the high specific surface area modified microporous activated carbon and is composed of hydrophobically modified 13X zeolite molecular sieve and organic metal framework material MOFs with a mass ratio of 10:3;

[0075] Material G: Compared with material A, the methane adsorption material removes the hydrophobically modified 13X zeolite molecular sieve and is a high specific surface area modified microporous activated carbon and organic metal framework material MOFs with a mass ratio of 7:3;

[0076] H material: Compared with A material, the methane adsorption material is molecular sieve MS-5A, high specific surface area modified microporous activated carbon, and organic metal framework material MOFs with a mass ratio of 10:7:3;

[0077] Material I: Compared with material A, the methane adsorption material is hydrophobically modified 13X zeolite molecular sieve, graphene aerogel GA-100, and organic metal framework material MOFs in a mass ratio of 10:7:3.

[0078] Evaluation experimental steps:

[0079] 1. Sample preparation: Accurately weigh the adsorbent sample, place it in a clean reactor, and pretreat it to remove impurities and moisture on the surface and pores of the adsorbent.

[0080] 2. Device assembly and leak detection: Connect the reactor to the static volumetric adsorption device, which usually includes high-precision pressure sensors, temperature sensors, vacuum pumps, gas storage tanks, and other components. Check the airtightness of the entire device to ensure there are no leaks.

[0081] 3. Vacuuming and degassing: Use a vacuum pump to vacuum the sample tube and the entire device to remove air and other impurities in the instrument. Vacuum until the pressure reaches less than 10 -3 Pa).

[0082] 4. Gas charging and adsorption: Fill the device with high-purity methane gas and record the initial pressure and temperature. Allow the methane gas to fully contact the adsorbent and reach adsorption equilibrium. Record the pressure and temperature at the adsorption equilibrium state.

[0083] 5. Data Calculation: Based on the ideal gas state equation pV = nRT, combined with the initial and equilibrium pressures, temperatures, and gas mass, the adsorbent's methane adsorption capacity is calculated. By varying the methane charge, multiple experiments are conducted and adsorption isotherms are plotted. When the adsorption capacity no longer increases significantly with increasing pressure, the corresponding adsorption capacity is considered saturated. Finally, the saturated adsorption capacity (wt%) is divided by the mass of the adsorbent.

[0084] Table 1 Comparison of methane adsorption capacity of adsorbents at 20 ℃ and 4 MPa

[0085] It can be concluded from Table 1 that the methane adsorption materials of materials A, B, and C configured according to the formula of this application have the best adsorption effect. The proportion of the methane adsorption material used in the DG material is not within the required range. The lack of any one of the methane adsorption materials will lead to a deterioration in the saturated adsorption capacity. Replacing any adsorption material with the HI material will also lead to a deterioration in the saturated adsorption capacity, which does not reach a good level.

[0086] The above experimental data and engineering design show that the present invention can significantly reduce the risk of methane enrichment in the wellbore in the early stage of gas invasion by optimizing the synergistic effect of the adsorption material ratio and the injection process, providing a new idea for well control in deep wells with high pressure gas layers.

[0087] In the blowout control method based on wellhead methane adsorption provided by the present invention, by optimizing the type and ratio of methane adsorption materials and combining them with other necessary drilling fluid additives to form a high-density composite well-killing fluid, the slippage and rise of methane bubbles in the wellbore can be effectively suppressed, and methane gas can be adsorbed in real time, thereby effectively controlling the expansion of the gas column and the increase in pressure in the early stages of gas invasion, preventing the occurrence of blowouts or curbing their development. This method meets the safety and efficiency requirements of blowout control technology in the field of blowout prevention technology in oil and gas drilling operations, and has theoretical feasibility and potential effectiveness in practical application.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A blowout control method based on wellhead methane adsorption, characterized in that: The method comprises the following steps: S1. Startup phase: Real-time monitoring of the methane concentration of the gas returning from the wellhead. When the methane concentration is ≥5%, the blowout control method is immediately started. S2. Composite Kill Fluid Injection: Inject the composite kill fluid into the wellbore at a depth of 100-200 meters below the wellhead through coiled tubing or kill line to ensure full contact with the rising gas intrusion fluid; the composite kill fluid contains a methane adsorbent, a weighting agent, a dispersant, a fluid loss additive, a thickener, and water or a base fluid; S3. Real-time monitoring and dynamic control of the injection process: During the injection of the composite killing fluid, the pressure, temperature, and methane gas concentration in the wellbore are monitored in real time, with a monitoring frequency of at least once per second. Based on the real-time monitoring data, the injection rate and / or injection pressure of the composite killing fluid are dynamically adjusted to maintain a stable flow pattern and uniform distribution of the killing fluid in the wellbore; S4. Post-injection monitoring and effect confirmation: After the injection of the composite killing fluid is completed, the pressure changes in the wellbore are continuously monitored until the pressure change rate is less than ±0.1 MPa / minute and the pressure remains stable for more than 30 minutes to confirm that the blowout risk has been effectively controlled; The methane adsorption material is a hydrophobically modified 13X zeolite molecular sieve, a high specific surface area modified microporous activated carbon, and an organic metal framework material MOFs in a mass ratio of (10-12): (7-8): (2-3); The hydrophobically modified 13X zeolite molecular sieve has a pore size of 9-10Å, a water contact angle greater than 130°, and a particle size of 1-5μm; The pore size of the high specific surface area modified microporous activated carbon is concentrated in the micropore range of less than 2 nm, the water contact angle is greater than 130°, and the particle size is 100-150 μm.

2. The blowout control method based on wellhead methane adsorption according to claim 1, characterized in that: The weighting agent is selected from at least one of micronized hematite, micronized ilmenite, barite powder, and micro manganese ore powder; the dispersant is selected from at least one of lignin sulfonate and acrylic acid-sulfonate copolymer; the thickener is selected from at least one of xanthan gum, modified starch, modified cellulose, and hydroxypropyl guar gum; and the fluid loss additive is selected from at least one of polyanionic cellulose, hydrophobically modified nano-silica, and sulfonated asphalt.

3. The blowout control method based on wellhead methane adsorption according to any one of claims 1-2, characterized in that: The contents of the components in the composite well killing fluid are as follows by mass percentage: methane adsorbent 18-25%, weighting agent 35-50%, dispersant 0.3-1.5%, thickener 0.8-2.0%, fluid loss additive 0.8-2.0%, and the balance water or base liquid; The density of the composite well killing fluid is 2.0-2.5 g / cm³.

4. The blowout control method based on wellhead methane adsorption according to claim 3, characterized in that: The composite well-killing fluid further comprises, by mass percentage, a defoaming agent of 0.05-0.15%, a pH regulator of 0.05-0.2%, and a wetting agent of 0-1%; the defoaming agent is one of an organosilicon emulsion, a polyether-modified silicone oil, and a polysiloxane emulsion; the pH regulator is one of sodium hydroxide and magnesium oxide; and the wetting agent is one of an ethoxylated alcohol, sulfomethyl ethyl glucoside, and a polyether-modified silicone oil.

5. The blowout control method based on wellhead methane adsorption according to claim 4, characterized in that: The total amount of the dispersant, thickener, fluid loss additive, defoamer, pH regulator and wetting agent added accounts for 2.5% to 3.5% of the total mass of the composite well-killing fluid.

6. The blowout control method based on wellhead methane adsorption according to claim 1, characterized in that: In step S2, the injection rate of the composite well-killing fluid is 0.5-3.0 m 3 / min, the injection pressure control range is 5-50 MPa, and does not exceed 80% of the formation fracture pressure. The single injection volume is 1.2-2.5 times the wellbore volume. During the injection process, the annular return velocity is ensured to be ≥0.8 m / s.

7. The blowout control method based on wellhead methane adsorption according to claim 1, characterized in that: In step S3, dynamic adjustment adopts a closed-loop control algorithm: when the real-time monitored wellbore pressure fluctuation exceeds ±0.5 MPa, the temperature deviates from the base temperature by ±15°C, the methane concentration is ≥3%, or the methane content of the return fluid is ≥10%, the injection rate and pressure of the composite well-killing fluid are automatically adjusted to maintain the stability of the flow state in the wellbore.

8. The blowout control method based on wellhead methane adsorption according to claim 1, characterized in that: The real-time monitoring data in steps S3 and S4 are synchronized to the control center via a wireless transmission system; the pressure monitoring equipment uses a high-precision sensor with an error of ≤±0.1%FS.

Images