Emergency rescue method and emergency response method for out-of-control blowout of underwater wellhead of offshore platform

Abstract

The invention provides an emergency rescue method and an emergency response method after out-of-control blowout of an underwater wellhead of an offshore platform, and the method comprises the steps: starting rescue well operation preparation, rescue well design and rescue well drilling operation based on an offshore underwater wellhead when out-of-control blowout of the wellhead occurs; starting oil spilling control; emergency response personnel mobilization and emergency equipment mobilization are carried out, and the following steps are carried out: S1, accident well area investigation; s2, evaluating the condition of an underwater wellhead; s3, performing ROV intervention operation; s4, carrying out underwater obstacle removing operation; s5, the emergency plugging device plugs the underwater wellhead; the emergency rescue method and the emergency response method provided by the invention are suitable for handling most offshore platform underwater wellhead blowout dangerous cases; according to the emergency rescue method and the emergency response method, the accident platform condition, the accident state, the personnel and equipment condition and the field environment factor are comprehensively considered, a method basis is provided for accident wellhead control and treatment, and the blank of the domestic offshore platform underwater wellhead well control emergency rescue method and technology is filled.

Description

Technical Field

[0001] The invention belongs to the field of well control for offshore drilling and completion operations, and in particular relates to a rescue method after an underwater wellhead blowout on an offshore platform is out of control. Background Art

[0002] The ocean is rich in oil and gas resources. The development of marine oil and gas has both broad prospects and huge risks and challenges. The offshore oil and gas exploitation operation area is far from the shore, the natural and climatic environment is harsh, and the personnel and facilities are concentrated. Once an accident such as a blowout explosion occurs, it is easy to produce a chain reaction. If it is not handled properly, it will cause casualties, environmental pollution and other major production safety accidents. In response to the potential risks of offshore oil and gas development, foreign countries have successively formulated a series of laws and regulations or standards and specifications to form a complete set of underwater wellhead offshore well control rescue processes, methods and technologies. As domestic offshore oil and gas development moves towards deep water, the risk of offshore oil and gas well control is more prominent, and there is an urgent need for a set of well control rescue methods suitable for underwater wellheads of domestic offshore platforms. Invention content

[0003] In view of this, the present invention aims to propose a rescue method and emergency response method after a blowout at an underwater wellhead of an offshore platform is out of control, so as to deal with the blowout at the underwater wellhead of the offshore platform, provide a methodological basis for the control and treatment of the accident wellhead, and fill the gap in the rescue methods and technologies for the wellhead control of underwater wellheads of domestic offshore platforms.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A rescue method for an underwater wellhead blowout on an offshore platform, based on an underwater wellhead, where a blowout is out of control, rescue well operation preparation, rescue well design and rescue well drilling operations are initiated; oil spill control is initiated; emergency response personnel and emergency equipment are mobilized, and the following steps are implemented:

[0006] S1. Investigation of the accident well area: the accident well area is investigated by underwater ROV, and the accident well area investigation includes determining the status of submarine equipment and facilities, the degree of wellhead damage and the location of oil spill;

[0007] S2. Underwater wellhead condition assessment: conducting underwater wellhead condition assessment based on the results of the accident well area survey;

[0008] S3, ROV intervention operation, according to the results of the accident well area survey and the underwater wellhead condition assessment results, the original blower control system is operated through ROV intervention to achieve re-control of the underwater blowout preventer;

[0009] S4, underwater obstacle removal operation, based on the results of the accident well area survey and the underwater wellhead condition assessment results, use obstacle removal tools or ROV system to remove objects near the accident wellhead that affect emergency rescue work, and establish an installation environment for the wellhead emergency plugging device;

[0010] S5. The emergency plugging device plugs the underwater wellhead. The wellhead emergency plugging device is installed and operated at the wellhead of the accident well to regain control of the wellhead. If the accident well cannot be shut down, the side diversion port of the wellhead emergency plugging device is used to divert and recover the blowout fluid, or the rescue well is cooperated to carry out well pressure operation.

[0011] Furthermore, when a blowout occurs at the wellhead and becomes uncontrolled, an emergency command group should be immediately established to command and implement the emergency rescue method.

[0012] Furthermore, the emergency response personnel mobilization includes: technical support personnel mobilization and maritime rescue team personnel mobilization; the emergency equipment mobilization includes the following steps: activating the underwater wellhead blowout preventer control system ROV intervention technology package and underwater emergency sealing system, underwater wellhead emergency disposal system equipment; activating the underwater oil spill disposal system, and preparing for the release of underwater oil spill chemical dispersants.

[0013] Furthermore, after the rescue well drilling operation, the following steps are also included:

[0014] A3.3. Well pressure: After the rescue well is connected to the accident well, the well is pressured to control the blowout of the accident well.

[0015] Furthermore, the oil spill control comprises the following steps:

[0016] A6. Underwater oil spill assessment: formulate and submit an application for the use of underwater crude oil dispersants based on the underwater oil spill conditions detected;

[0017] A6.1. Formulate an underwater crude oil dispersant release plan, which includes the release procedure, planned release area, release materials and the amount of release materials;

[0018] A6.2. Crude oil dispersant release equipment is in place, including an underwater oil spill chemical dispersant release system;

[0019] A6.3. For underwater oil spill control operations, the surface vessel station or the submarine pump station pumps the chemical dispersant to the submarine release distribution pipe, and then the dispersant is transported to each leakage point through the distribution pipe for injection and spraying.

[0020] Furthermore, in step S5, the diversion recovery operation includes the following steps: when the underwater wellhead is emergency sealed, if it is detected during the well shut-in operation that the pressure in the well exceeds the maximum pressure that can be tolerated to maintain the integrity of the wellbore, it is necessary to open the valve on the diversion blowout pipe of the sealing device to release the pressure to ensure the integrity of the wellbore; in order to reduce the pollution of the environment to the blowout oil spill, the fluid sprayed from the interface of the diversion blowout pipe line of the wellhead sealing device is collected on the surface ship through the underwater pipeline and manifold with a riser, and finally transported back to land for treatment through the deployment and connection of seabed and surface ships.

[0021] The present invention also provides an emergency response method after a blowout at an underwater wellhead of an offshore platform is out of control, comprising the emergency response method after a blowout at an underwater wellhead of an offshore platform is out of control, and further comprising the following steps:

[0022] B3. Establish technical support for equipment manufacturers. Equipment manufacturers shall formulate technical documents on equipment operation, maintenance, dynamic inspection and transportation deployment requirements based on the main technical specifications and structural characteristics of the equipment;

[0023] B5. Logistics and on-site inspections, develop guidance on how to arrange equipment transportation and communicate more effectively with transporters, so as to mobilize emergency response equipment more quickly;

[0024] B6. Establish a rescue well emergency plan and prepare a design and drilling document for drilling one or more rescue wells;

[0025] B7. Establish an underwater crude oil dispersant release plan and formulate operational instructions or plans for the release of crude oil dispersants during underwater oil spill disposal.

[0026] Furthermore, the emergency response method after an underwater wellhead blowout at an offshore platform is out of control also includes the following steps:

[0027] B1. Emergency response plan, formulate safe operation area control map for well control emergency response operations at sea accident well locations;

[0028] B2. Oil spill response plan: formulate and submit an application for the use of underwater crude oil dispersants according to the on-site underwater oil spill investigation;

[0029] B4. Source control emergency plan: formulate emergency equipment partial modification projects based on on-site survey feedback, mobilize corresponding technical expert groups or manufacturers, and carry out emergency design, manufacture or modification of equipment according to on-site conditions;

[0030] B8. Wellhead emergency plugging procedure: Based on the ROV intervention operation and obstacle clearance feedback information of the underwater blowout preventer control system, modify the underwater wellhead emergency plugging interface or install other auxiliary structures, and then formulate an underwater deployment plan.

[0031] Compared with the prior art, the rescue method after an underwater wellhead blowout on an offshore platform created by the present invention has the following advantages:

[0032] The rescue method and emergency response method created by the present invention are suitable for handling dangerous situations after blowouts at underwater wellheads of most offshore platforms; the rescue method and emergency response method comprehensively consider the conditions of the accident platform, the accident status, the conditions of personnel and equipment, and the on-site environmental factors, and formulate a rescue method flow chart and an emergency response method flow chart to deal with uncontrolled blowouts at underwater wellheads of offshore platforms, provide a methodological basis for controlling and handling accident wellheads, and fill the gap in domestic offshore platform underwater wellhead well control rescue methods and technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0034] Figure 1 A flow chart of a rescue method after an underwater wellhead blowout on an offshore platform as described in an embodiment of the present invention;

[0035] Figure 2 The present invention creates an emergency response flow chart after an underwater wellhead blowout on an offshore platform loses control as described in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] 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.

[0037] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0038] like Figure 1 As shown, a rescue method after a blowout at an underwater wellhead of an offshore platform is provided. Based on an underwater wellhead at sea, a blowout at the wellhead is out of control. The rescue well operation preparation A3, rescue well design A3.1 and rescue well drilling operation A3.2 are started; oil spill control is started; emergency response personnel mobilization A4 and emergency equipment mobilization A5 are carried out, and the following steps are implemented:

[0039] S1. Investigation of the accident well area: the accident well area is investigated by underwater ROV, and the accident well area investigation includes determining the status of submarine equipment and facilities, the degree of wellhead damage and the location of oil spill;

[0040] S2. Underwater wellhead condition assessment: conducting underwater wellhead condition assessment based on the results of the accident well area survey;

[0041] S3, ROV intervention operation, according to the results of the accident well area survey and the underwater wellhead condition assessment results, the original blowout control system is operated through ROV intervention, in order to achieve the re-control of the underwater blowout preventer; ROV is the abbreviation of Remotely Operated Vehicle, which is an important equipment for unmanned diving underwater operations and an underwater robot used for underwater observation, inspection and construction;

[0042] S4, underwater obstacle removal operation, based on the results of the accident well area survey and the underwater wellhead condition assessment results, use obstacle removal tools or ROV system to remove objects near the accident wellhead that affect emergency rescue work, and establish an installation environment for the wellhead emergency plugging device;

[0043] S5. The emergency plugging device plugs the underwater wellhead. The wellhead emergency plugging device is installed and operated at the wellhead of the accident well to regain control of the wellhead. If the accident well cannot be shut down, the side diversion port of the wellhead emergency plugging device is used to divert and recover the blowout fluid, or the rescue well is cooperated to carry out well pressure operation.

[0044] A method for emergency rescue after an underwater wellhead blowout on an offshore platform is out of control, wherein steps S1, S2 and S3 are combined to achieve a preliminary assessment and investigation of the accident site and equipment to determine the obstacle structures or equipment that can or must be removed, and provide accurate data for the subsequent step S4; the goal of the underwater obstacle removal operation in step S4 includes removing various objects that affect the safety of emergency response work above or near the accident wellhead, and, if necessary, also includes wellhead devices such as blowout preventers on the wellhead, so as to establish an environment capable of performing underwater intervention operations or installing wellhead emergency plugging devices, so as to shut in the well;

[0045] It is necessary to further explain that the rescue well, also known as the pressure relief well, is a well that is drilled at a certain distance from the accident well by using drilling equipment after a blowout accident occurs, and connected to the accident well. Through the rescue well, cementing, water flooding, dynamic well pressure and other methods are used to control the accident well.

[0046] like Figure 1 As shown, when a blowout occurs at the wellhead and becomes uncontrolled, an emergency command group A2 should be immediately established to command and implement the rescue method.

[0047] like Figure 1 As shown, the emergency response personnel mobilization A4 includes: technical support personnel mobilization A4.1 and maritime rescue team personnel mobilization A4.2; the emergency equipment mobilization includes the following steps: activating the underwater wellhead blowout preventer control system ROV intervention technology package and the underwater emergency sealing system, underwater wellhead emergency disposal system equipment; activating the underwater oil spill disposal system, and making preparations for the release of underwater oil spill chemical dispersants.

[0048] After the rescue well drilling operation A3.2, the following steps are also included:

[0049] A3.3. Well pressure: After the rescue well is connected to the accident well, the well is pressured to control the blowout of the accident well.

[0050] It should be further explained that: well killing refers to the process of controlling the wellhead back pressure and pumping in well killing fluid to remove the formation fluid invading the annular space and restore the downhole pressure balance.

[0051] like Figure 1 As shown, the oil spill control comprises the following steps:

[0052] A6. Underwater oil spill assessment: formulate and submit an application for the use of underwater crude oil dispersants based on the underwater oil spill conditions detected;

[0053] A6.1. Formulate an underwater crude oil dispersant release plan, which includes the release procedure, planned release area, release materials and the amount of release materials;

[0054] A6.2. Crude oil dispersant release equipment is in place, including an underwater oil spill chemical dispersant release system;

[0055] A6.3. For underwater oil spill control operations, the surface vessel station or the submarine pump station pumps the chemical dispersant to the submarine release distribution pipe, and then the dispersant is transported to each leakage point through the distribution pipe for injection and spraying.

[0056] In step S5, the diversion recovery operation includes the following steps: when the underwater wellhead is emergency plugged, if it is detected during the well shut-in operation that the pressure in the well exceeds the maximum pressure that can be tolerated to maintain the integrity of the wellbore, it is necessary to open the valve on the diversion blowout pipe line of the plugging device to release the pressure to ensure the integrity of the wellbore; in order to reduce the pollution of the environment to the blowout oil spill, the fluid ejected from the interface of the diversion blowout pipe line of the wellhead plugging device is collected to the surface ship through the underwater pipeline, manifold and riser through the deployment and connection of seabed and surface ships, and finally transported back to land for treatment.

[0057] like Figure 2 As shown, an emergency response method for an underwater wellhead blowout on an offshore platform includes the emergency rescue method for an underwater wellhead blowout on an offshore platform, and further includes the following steps:

[0058] B3. Establish technical support for equipment manufacturers. Equipment manufacturers shall formulate technical documents on equipment operation, maintenance, dynamic inspection and transportation deployment requirements based on the main technical specifications and structural characteristics of the equipment;

[0059] B5. Logistics and on-site inspections, develop guidance on how to arrange equipment transportation and communicate more effectively with transporters, so as to mobilize emergency response equipment more quickly;

[0060] B6. Establish a rescue well emergency plan and prepare a design and drilling document for drilling one or more rescue wells;

[0061] B7. Establish an underwater crude oil dispersant release plan and formulate operational instructions or plans for the release of crude oil dispersants during underwater oil spill disposal.

[0062] Furthermore, the emergency response method after an underwater wellhead blowout at an offshore platform is out of control also includes the following steps:

[0063] B1. Emergency response plan, formulate safe operation area control map for well control emergency response operations at sea accident well locations;

[0064] B2. Oil spill response plan: formulate and submit an application for the use of underwater crude oil dispersants according to the on-site underwater oil spill investigation;

[0065] B4. Source control emergency plan: formulate emergency equipment partial modification projects based on on-site survey feedback, mobilize corresponding technical expert groups or manufacturers, and carry out emergency design, manufacture or modification of equipment according to on-site conditions;

[0066] B8. Wellhead emergency plugging procedure: Based on the ROV intervention operation and obstacle clearance feedback information of the underwater blowout preventer control system, modify the underwater wellhead emergency plugging interface or install other auxiliary structures, and then formulate an underwater deployment plan.

[0067] As an example of the present invention, the rescue method and emergency response method process are as follows:

[0068] (1) Immediately establish an emergency command team A2 and a China National Offshore Oil Corporation Well Control Center emergency command team, and appoint internal commanders, liaison officers, and material organizers;

[0069] (2) Mobilization of emergency response personnel A4: Mobilize emergency response personnel and assemble according to the instructions of the accident handling management command group of the oil company;

[0070] (3) Emergency equipment mobilization A5, call up the contact list of external suppliers or technical partners, and send emergency response resource information consultation to relevant partners: rescue well technical support companies / institutions, emergency equipment modification / manufacturing factories, emergency equipment logistics and transportation organizations, etc.;

[0071] (4) Mobilization of technical support personnel A4.1: Confirm the shore-based technical support personnel, form an emergency response technical team, and send them to the accident handling management command team of the oil company, and form a technical support team for the accident handling command team with the drilling platform party;

[0072] (5) Mobilization of marine rescue team personnel A4.2: Confirm the marine rescue team personnel, form a marine emergency response operation team, and transfer them to the accident handling management general command team of the oil company. According to the instructions of the general command team, they are responsible for the deployment and operation of marine well control emergency response equipment;

[0073] (6) Survey the accident area S1, formulate a safe operation area control map B1 for the sea area accident well location and well control emergency response operations, and submit it to the accident disposal management general command team for review; the control map includes the control area, the entry path of the engineering vessel, the survey path, the deployment and installation of underwater equipment, the scheduled location of the rescue well operation well, and the emergency evacuation route, etc.;

[0074] (7) Subsea wellhead condition assessment S2: Based on the information of the underwater BOP group provided by the accident platform, the ROV intervention operation system documents of the underwater BOP control system and the underwater wellhead emergency plugging system of the China National Offshore Oil Corporation Well Control Center were reviewed. According to the data of the underwater BOP system, wellhead system and on-site survey feedback of the accident platform, the existing system documents were revised to ensure the correct operation of the ROV intervention control of the underwater BOP control system and the underwater wellhead emergency plugging during the emergency response operation;

[0075] (8) Source control emergency plan B4: Based on the feedback from the on-site survey, initiate the emergency equipment partial modification project B4, mobilize the corresponding technical expert group or manufacturer, and carry out emergency design, manufacture or modification of equipment (additional equipment, etc.) according to the on-site conditions;

[0076] (9) Logistics and transportation and on-site investigation B5: For blowout emergency response outside the South China Sea area, conduct an evaluation of the transportation efficiency of underwater emergency response equipment, and dismantle and subcontract transportation plans that may occur during the mobilization process (if necessary), follow the plan of the general command team, and contact relevant transportation agencies, lifting agencies, and sea, land and air transportation insurance plans;

[0077] (10) ROV intervention operation S3, arrange for the heavy ROV system and other survey equipment, underwater blowout preventer control system ROV intervention operation equipment to be loaded onto the designated engineering vessel, and select the equipment according to the preliminary on-site survey results and the accident wellhead equipment information (underwater allocation authority system, etc.). Load the ship according to the loading plan, and after the equipment handover procedures are completed, mobilize to the accident site operation area, arrive at the designated location of the on-site joint operation coordination group, and start participating in the secondary survey and underwater blowout preventer control system ROV intervention operation;

[0078] (11) Underwater oil spill situation assessment A6: According to the underwater oil spill situation at the scene, formulate and submit an application for the use of underwater crude oil dispersant B2, which includes the type and required amount of underwater crude oil dispersant, and mobilize the underwater crude oil dispersant release system equipment;

[0079] (12) Formulate underwater crude oil dispersant release plan A6.1. Based on the secondary survey information, formulate a plan for the use of underwater crude oil dispersant release engineering vessels and underwater obstacle removal equipment deployment vessels, and submit an application to the general command team;

[0080] (13) Crude oil dispersant release equipment is in place A6.2. According to the approved underwater oil spill crude oil dispersant release plan and underwater clearance plan, the corresponding equipment is dispatched for loading on board and then transported to the designated sea area;

[0081] (14) Underwater oil spill operations A6.3 and underwater clearance operations S4: Under the instructions of the on-site joint coordination operation team, carry out response operations in accordance with the underwater oil spill crude oil dispersant release plan and underwater clearance plan;

[0082] (15) Emergency plugging device plugs the underwater wellhead S5. The underwater wellhead emergency plugging system is mobilized. According to the feedback information of the underwater blowout preventer control system ROV intervention operation and obstacle clearance operation, the underwater wellhead emergency plugging interface is modified or other auxiliary structural parts are installed. According to the underwater deployment plan, the underwater wellhead emergency plugging system is loaded onto the designated engineering vessel and transported to the designated sea area as required. Deploy according to the instructions of the on-site joint operation coordination group to complete the wellhead plugging;

[0083] (16) Rescue well operation preparation A3: Based on the well location geological parameters provided by the oil company, the accident well design documents and operation records, and information such as drilling platform specifications, rescue well operation design and well control risk analysis and control can be carried out;

[0084] (17) Rescue Well Design A3.1. Submit rescue well support documents (personnel information, equipment information, etc.) to the incident management command team so that the oil company logistics and logistics team can make transportation arrangements and equipment installation and modification on the target platform;

[0085] (18) Rescue well design A3.1. Organize technical personnel to carry out rescue well modeling simulation calculation and analysis, complete the simulation analysis and risk identification and control of rescue well design, form rescue well design documents, and submit them to the accident disposal management command group for approval;

[0086] (19) Rescue well drilling operations A3.2. Install the equipment on the platform in accordance with the rescue well drilling operations of the oil company. After the platform reaches the designed well location, carry out drilling operations according to the approved rescue well design until the well is finally killed, so that the accident well is completely and effectively controlled.

[0087] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A rescue method for an underwater wellhead blowout on an offshore platform, based on an underwater wellhead at sea, characterized by: In the event of a blowout at the wellhead, the rescue well operation preparation (A3), rescue well design (A3.1) and rescue well drilling operation (A3.2) are initiated; oil spill control is initiated; emergency response personnel mobilization (A4) and emergency equipment mobilization (A5) are carried out, and the following steps are implemented: S1. Investigation of the accident well area: the accident well area is investigated by underwater ROV, and the accident well area investigation includes determining the status of submarine equipment and facilities, the degree of wellhead damage and the location of oil spill; S2. Underwater wellhead condition assessment: conducting underwater wellhead condition assessment based on the results of the accident well area survey; S3, ROV intervention operation, according to the results of the accident well area survey and the underwater wellhead condition assessment results, the original blower control system is operated through ROV intervention to achieve re-control of the underwater blowout preventer; S4, underwater obstacle removal operation, based on the results of the accident well area survey and the underwater wellhead condition assessment results, use obstacle removal tools or ROV system to remove objects near the accident wellhead that affect emergency rescue work, and establish an installation environment for the wellhead emergency plugging device; S5. The emergency plugging device plugs the underwater wellhead. The wellhead emergency plugging device is installed and operated at the wellhead of the accident well to regain control of the wellhead. If the accident well cannot be shut down, the side diversion port of the wellhead emergency plugging device is used to divert and recover the blowout fluid, or the rescue well is cooperated to carry out well pressure operation.

2. The method for rescuing an underwater wellhead blowout on an offshore platform according to claim 1, characterized in that: When a blowout occurs at the wellhead and the well is out of control, an emergency command group (A2) should be immediately established to command and implement the emergency rescue method.

3. The method for rescuing an underwater wellhead blowout on an offshore platform according to claim 1, characterized in that: The emergency response personnel mobilization (A4) includes: technical support personnel mobilization (A4.1) and maritime rescue team personnel mobilization (A4.2); the emergency equipment mobilization includes the following steps: activating the underwater wellhead blowout preventer control system ROV intervention technology package and the underwater emergency sealing system, underwater wellhead emergency disposal system equipment; activating the underwater oil spill disposal system, and preparing for the release of underwater oil spill chemical dispersants.

4. The emergency rescue method after an underwater wellhead blowout on an offshore platform according to claim 1 is characterized in that: After the rescue well drilling operation (A3.2), the following steps are also included: A3.

3. Well pressure: After the rescue well is connected to the accident well, the well is pressured to control the blowout of the accident well.

5. The method for rescuing an underwater wellhead blowout on an offshore platform according to claim 1, characterized in that: The oil spill control comprises the following steps: A6. Underwater oil spill assessment: formulate and submit an application for the use of underwater crude oil dispersants based on the underwater oil spill conditions detected; A6.

1. Formulate an underwater crude oil dispersant release plan, which includes the release procedure, planned release area, release materials and the amount of release materials; A6.

2. Crude oil dispersant release equipment is in place, including an underwater oil spill chemical dispersant release system; A6.

3. For underwater oil spill control operations, the surface vessel station or the submarine pump station pumps the chemical dispersant to the submarine release distribution pipe, and then the dispersant is transported to each leakage point through the distribution pipe for injection and spraying.

6. The method for rescuing an underwater wellhead blowout on an offshore platform according to claim 1, characterized in that: In step S5, the diversion recovery operation includes the following steps: when the underwater wellhead is emergency plugged, when it is detected during the well shut-in operation that the pressure in the well exceeds the maximum pressure that can be tolerated to maintain the integrity of the wellbore, it is necessary to open the valve on the diversion blowout pipe line of the plugging device to release the pressure to ensure the integrity of the wellbore; in order to reduce the pollution of the environment to the blowout oil spill, the fluid ejected from the interface of the diversion blowout pipe line of the wellhead plugging device is collected on the surface ship through the underwater pipeline, manifold and riser through the deployment and connection of seabed and surface ships, and finally transported back to land for treatment.

7. An emergency response method for an underwater wellhead blowout on an offshore platform, characterized in that: The method for rescuing an underwater wellhead blowout on an offshore platform according to any one of claims 1 to 6 further comprises the following steps: B3. Establish technical support for equipment manufacturers. Equipment manufacturers shall formulate technical documents on equipment operation, maintenance, dynamic inspection and transportation deployment requirements based on the main technical specifications and structural characteristics of the equipment; B5. Logistics and on-site inspections, develop guidance on how to arrange equipment transportation and communicate more effectively with transporters, so as to mobilize emergency response equipment more quickly; B6. Establish a rescue well emergency plan and prepare a design and drilling document for drilling one or more rescue wells; B7. Establish an underwater crude oil dispersant release plan and formulate operational instructions or plans for the release of crude oil dispersants during underwater oil spill disposal.

8. The emergency response method after an underwater wellhead blowout at an offshore platform according to claim 7 is characterized in that: The following steps are also included: B1. Emergency response plan, formulate safe operation area control map for well control emergency response operations at sea accident well locations; B2. Oil spill response plan: formulate and submit an application for the use of underwater crude oil dispersants according to the on-site underwater oil spill investigation; B4. Source control emergency plan: formulate emergency equipment partial modification projects based on on-site survey feedback, mobilize corresponding technical expert groups or manufacturers, and carry out emergency design, manufacture or modification of equipment according to on-site conditions; B8. Wellhead emergency plugging procedure: Based on the ROV intervention operation and obstacle clearance feedback information of the underwater blowout preventer control system, modify the underwater wellhead emergency plugging interface or install other auxiliary structures, and then formulate an underwater deployment plan.

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