CN117145388A - Suction anchor for ocean drilling and drilling method - Google Patents

Abstract

The application belongs to the technical field of ocean drilling, and particularly relates to an ocean drilling suction anchor and a drilling method. The application comprises a suction anchor cylinder, a sleeve assembly, a drainage mechanism and an exhaust mechanism; the drainage mechanism and the exhaust mechanism are communicated with the cylinder cavity and are respectively used for discharging gas and liquid in the cylinder cavity; the sleeve assembly is arranged along the axial direction of the suction anchor cylinder body, the sleeve assembly is provided with a drilling channel penetrating through the upper end and the lower end of the sleeve assembly, the upper end of the sleeve assembly penetrates through the top wall of the suction anchor cylinder body, the upper end of the sleeve assembly extends upwards compared with the upper surface of the suction anchor cylinder body, and the upper end of the sleeve assembly is also provided with a drilling installation mechanism which is used for being detachably connected with a drilling system; the lower end of the sleeve assembly is provided with a pre-inclined section close to the avoidance opening, and the pre-inclined section gradually deviates from the axis of the sleeve assembly from top to bottom. The suction anchor cylinder body disclosed by the application can be suitable for deep sea shallow layer well construction, and is more sufficient in development and utilization of deep sea shallow layer oil gas resources.

Description

Suction anchor for ocean drilling and drilling method

Technical Field

The application belongs to the technical field of ocean drilling, and particularly relates to an ocean drilling suction anchor and a drilling method.

Background

In recent years, the petroleum and petrochemical industry is rapidly developed, and advanced technologies are continuously emerging; the development of offshore oil exploration and natural gas development and utilization are increasingly important in industry development and national economy. With the great development of offshore oil and gas, the research of drilling technology is of great importance. Marine drilling refers to the general term for oil and gas exploration and development drilling operations in the marine area. According to sea area, the method is divided into: the drilling operation of shallow sea areas generally refers to sea areas close to coasts with water depths ranging from 2 m to 5 m; the drilling operation of the offshore area generally refers to a sea area with the periphery of the shallow sea area far away from the shore and the water depth of 5-450 m; the open sea drilling operation is generally directed to a sea area which is far from the coast and has a water depth of more than 450 m. Ocean drilling is generally divided into: (1) shallow water within 500 m; (2) 500 m-1500 m is deep water; (3) the ultra-deep water is more than 1500 m. The deep sea shallow layer is also provided with considerable oil and gas resources generally, but because the intensity of the deep sea shallow layer non-diagenetic stratum is not high, the soil is soft and the soil layer is thicker, if the surface layer conduit and drill bit equipment for drilling are directly adopted, collapse easily occurs in the drilling process, so that the well is difficult to build in the deep sea shallow layer. Moreover, when the wellbores drilled through vertical surface conduits and casings in the prior art have the same bottom hole depth, the well inclination angle of the wellbores is small (the well inclination angle is the degree of deviation of the bottom hole from the vertical direction, which means the level of the bottom hole is better as the well bottom hole is larger, namely, the well bottom hole is closer to 90 degrees), so that the exploitation and the utilization of deep sea shallow oil and gas resources are not ideal. Moreover, the installation of the existing marine drilling suction anchor is inconvenient, so that the use of the marine drilling suction anchor is limited.

Disclosure of Invention

Aiming at the defects that the development and utilization of deep-sea shallow oil gas resources are not ideal in the prior art, the installation of the existing ocean drilling suction anchor is inconvenient, the use of the ocean drilling suction anchor is limited, and the like, the application provides the ocean drilling suction anchor and a drilling method.

The application provides a suction anchor for ocean drilling, which comprises a suction anchor cylinder body, a sleeve assembly, a drainage mechanism and an exhaust mechanism; the drainage mechanism and the exhaust mechanism are communicated with the cylinder cavity and are respectively used for discharging gas and liquid in the cylinder cavity; the suction anchor cylinder body is axially provided with a cylinder cavity, and the bottom of the suction anchor cylinder body is provided with an avoidance opening communicated with the cylinder cavity; the sleeve assembly is arranged along the axial direction of the suction anchor cylinder body, the sleeve assembly is provided with a drilling channel penetrating through the upper end and the lower end of the sleeve assembly, the upper end of the sleeve assembly penetrates through the top wall of the suction anchor cylinder body, the upper end of the sleeve assembly extends upwards compared with the upper surface of the suction anchor cylinder body, the upper end of the sleeve assembly is also provided with a drilling installation mechanism, the installation mechanism is positioned outside the suction anchor cylinder body, the drilling installation mechanism is used for being detachably connected with a drilling system and installing the drilling system to the upper end of the sleeve assembly, and the drilling channel is used for the telescopic movement of a drilling tool assembly of the drilling system and the flow of drilling fluid of the drilling tool assembly; the lower end of the sleeve assembly is provided with a pre-inclined section close to the avoidance opening, and the pre-inclined section gradually deviates from the axis of the sleeve assembly from top to bottom.

The suction anchor cylinder body and the sleeve component are matched, the suction anchor cylinder body and the sleeve component can be suitable for deep sea shallow layer well construction, the lower end of the pre-inclined sleeve is bent in advance by a certain angle, the well inclination angle of a borehole drilled by the suction anchor cylinder body and the sleeve component is larger when the suction anchor cylinder body and the drill bit device are matched for use, and the suction anchor cylinder body and the sleeve component are more fully developed and utilized for deep sea shallow layer oil and gas resources. The upper end of the sleeve assembly is also provided with a drilling installation mechanism which is convenient for the installation of a drilling system, and the drainage mechanism and the exhaust mechanism are respectively used for exhausting the gas and the liquid in the cavity of the cylinder body so as to facilitate the installation of the suction anchor cylinder body and the sleeve assembly on the deep sea shallow layer.

Preferably, the sleeve assembly comprises a surface layer conduit arranged on the base disc cylinder body and a pre-inclined sleeve arranged in the surface layer conduit, wherein the axis of the surface layer conduit and the axis of the pre-inclined sleeve are matched with the axis of the base disc cylinder body, and the height of a lower end pipe orifice of the pre-inclined sleeve is matched with the height of the avoidance opening;

the pre-inclined section is formed by gradually deviating from the axis of the surface layer catheter from top to bottom at the lower end of the pre-inclined sleeve; or the pre-inclined section is formed by gradually deviating the same side of the axis of the surface layer catheter from top to bottom from the lower ends of the pre-inclined sleeve and the surface layer catheter.

Preferably, the mounting mechanism comprises a low pressure wellhead and a high pressure wellhead; the low-pressure wellhead is arranged at the upper end pipe orifice of the surface layer conduit, and the high-pressure wellhead is arranged at the upper end pipe orifice of the pre-inclined sleeve.

Preferably, the marine drilling suction anchor is used for deep sea shallow drilling with an earthen surface; at least two sleeve assemblies are arranged along the axle center of the sleeve assemblies.

In another aspect, the application provides a drilling method comprising a drilling system and a marine drilling suction anchor as described above; the drilling process comprises the following steps:

s1, enabling the marine drilling suction anchor to move downwards so as to avoid an opening, enabling the lower end of the marine drilling suction anchor to be placed in a deep sea shallow layer, enabling a pre-inclined section of the sleeve assembly to be inserted into the deep sea shallow layer, and respectively discharging gas and liquid in the cylinder cavity by a water discharging mechanism and an air discharging mechanism;

s2, connecting a drilling system with a drilling installation mechanism to enable the drilling system to be installed at the upper end of the sleeve assembly, enabling drilling fluid provided by the drilling system to circularly flow between a drilling channel of the sleeve assembly and the drilling system, enabling a drilling tool assembly of the drilling system to stretch and retract in the drilling channel of the sleeve assembly, and enabling the drilling tool assembly and the drilling fluid to be matched to drill deep sea shallow layers.

Preferably, in step S2, the drilling system further comprises a drilling platform, wherein during drilling, seawater is used as drilling fluid, the drilling fluid is sprayed downwards from the drilling platform along the drill rod of the drilling tool assembly to flush the well from the bottom of the drill bit, and then the drilling fluid is discharged upwards from the annular space between the drill rod and the sleeve from the sleeve assembly to the seawater, and the drilling system drills to the designed well depth of the first stage;

the first stage designs well cementation after well deep drilling, and installs the underwater blowout preventer to the sleeve assembly in a descending way, the top of the underwater blowout preventer is connected to a sea surface drilling platform through a marine riser, thereby forming a closed loop, continuing drilling until the target oil extraction well is completed, and adopting mud as drilling fluid in the continuous drilling process.

Preferably, the well drilling system respectively drills wells through the casing assemblies to form at least two target oil extraction shafts correspondingly, and the target oil extraction shafts and the corresponding casing assemblies form at least two wellheads for oil extraction.

Preferably, the wellhead at least comprises a first wellhead and a second wellhead, a christmas tree is installed in the second wellhead, and the second wellhead is communicated with the first wellhead through a high-pressure pipeline.

Preferably, the christmas tree is installed and the high pressure pipeline is installed by means of an underwater robot.

Preferably, the marine drilling suction anchor installation parameters are also checked by an underwater robot.

Drawings

The foregoing and other objects, features and advantages of the application will be apparent from the following more particular description of preferred embodiments of the application, as illustrated in the accompanying drawings. Like reference numerals refer to like parts throughout the drawings, and the drawings are not intentionally drawn to scale on actual size or the like, with emphasis on illustrating the principles of the application.

FIG. 1 is a schematic structural view of a marine drilling suction anchor provided by an embodiment of the present application;

FIG. 2 is a schematic structural view of a marine drilling suction anchor at another perspective provided by an embodiment of the present application;

FIG. 3 is a cross-sectional view of a marine drilling suction anchor according to an embodiment of the present application;

fig. 4 is a cross-sectional view of a marine drilling suction anchor according to a second embodiment of the present application.

Reference numerals illustrate:

suction anchor cylinder 101, suction anchor top cover 102, reinforcement rib 103, sleeve assembly 104, diagonal brace 105, drain hole 106, exhaust hole 107, drain pipe 108, pump interface 109, exhaust pipe 110, exhaust valve 111, lifting hanging ring 112, avoidance opening 113; low pressure wellhead 201, high pressure wellhead 202, pre-inclined casing 203, high strength cement 204, surface conduit 205, installation mechanism 206, and drilling passageway 207;

Detailed Description

In order that the application may be understood more fully, the application will be described with reference to the accompanying drawings.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to and integrated with the other element or intervening elements may also be present. The terms "mounted," "one end," "the other end," and the like are used herein for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Embodiment one:

1-3, the suction anchor for the marine drilling comprises a suction anchor cylinder 101 and a sleeve assembly 104 arranged along the axial direction of the suction anchor cylinder 101, wherein an avoidance opening 113 is formed in the bottom of the suction anchor cylinder 101, the upper end of the sleeve assembly 104 extends upwards compared with the upper end of the suction anchor cylinder 101, and an external connecting port is formed at the upper end of the sleeve assembly 104; the sleeve assembly 104 comprises a surface conduit 205 arranged on the suction anchor cylinder 101 and a pre-inclined sleeve 203 arranged in the surface conduit 205, wherein the lower end of the pre-inclined sleeve 203 gradually deviates from the axis of the surface conduit 205 from top to bottom, and the lower end of the pre-inclined sleeve 203 forms a part which is bent compared with the axis of the surface conduit 205; further, a coaxial section is formed at the upper end of the pre-inclined sleeve 203, a pre-inclined section is formed at the lower end of the pre-inclined sleeve 203, the upper end of the pre-inclined section is connected with the lower end of the coaxial section, the coaxial section and the surface layer catheter 205 are coaxial, the angle between the axis of the pre-inclined section and the axis of the surface layer catheter 205 facing downwards is within 5 degrees, and the angle is generally 1-5 degrees. The lower end pipe orifice of the pre-inclined sleeve 203 and the lower end pipe orifice of the surface layer conduit 205 are positioned at the avoidance opening 113 at the bottom of the suction anchor cylinder 101; the axis of the skin conduit 205 is adapted to the axis of the suction anchor cylinder 101, and generally the skin conduit 205 is parallel to the axis of the suction anchor cylinder 101.

The mounting mechanism 206 includes a low pressure wellhead 201 and a high pressure wellhead 202. The low pressure wellhead 201 and the high pressure wellhead 202 are connected to the suction anchor cylinder 101 to install a drilling system, which is also typically provided with interfaces for adapting to the low pressure wellhead 201 and the high pressure wellhead 202, respectively. The upper end pipe orifice of the surface conduit 205 is provided with a low-pressure well head 201, the low-pressure well head 201 is higher than the upper surface of the suction anchor cylinder 101, the upper end pipe orifice of the pre-inclined sleeve 203 is provided with a high-pressure well head 202, the high-pressure well head 202 is higher than the upper end pipe orifice of the pre-inclined sleeve 203, and the high-pressure well head 202 and the low-pressure well head 201 are mutually matched to form an external connecting port. Further, the inner wall of the low-pressure wellhead 201 is further formed with a mounting groove, the sleeve assembly 104 further comprises a mounting tooth block arranged in the mounting groove, the mounting tooth block is sleeved at the upper end of the pre-inclined sleeve 203, the upper end of the pre-inclined sleeve 203 and the upper end of the surface conduit 205 are fixedly connected through the mounting tooth block, a cement layer 204 is arranged between the outer side wall of the lower end of the pre-inclined sleeve 203 and the inner side wall of the lower end of the surface conduit 205, and high-strength cement is generally filled in the cement layer to fix the lower end of the pre-inclined sleeve 203 and the lower end of the surface conduit 205. Further, the height of the lower end nozzle of the pre-inclined sleeve 203 is H1, the height H2 of the lower end nozzle of the surface conduit 205, the height H3 of the bottom avoidance opening 113 of the suction anchor cylinder 101, H3-50mm is less than or equal to H1 and less than or equal to h3+50mm, H3-50mm is less than or equal to H2 and less than or equal to h3+50mm, and h1=h2=h3 generally, that is, the lower end nozzle of the pre-inclined sleeve 203, the lower end nozzle of the surface conduit 205 and the bottom avoidance opening 113 of the suction anchor cylinder 101 are coplanar.

The upper end of suction anchor barrel 101 is equipped with suction anchor top cap 102, and suction anchor top cap 102 has been seted up and has been run through the installation through-hole of suction anchor top cap 102 upper and lower surface, and the upper end of top layer pipe 205 runs through the installation through-hole and is connected with the installation through-hole, and the marine drilling suction anchor still includes bracing 105, and the one end of bracing 105 is connected with the peripheral wall of top layer pipe 205 upper end, and the other end is connected with the upper end of suction anchor top cap 102. The diagonal braces 105 are generally triangular iron members, and the two perpendicular end surfaces of the diagonal braces 105 are respectively connected with the outer side wall of the surface conduit 205 and the upper end surface of the suction anchor cap 102. The sleeve assembly 104 is secured to the suction anchor cylinder 101 by the cooperation of the diagonal braces 105 and the mounting holes. Further, the suction anchor top cover 102 is also provided with a drain hole 106 and a drain hole 106, and the drain hole 106 respectively penetrate through the upper surface and the lower surface of the suction anchor top cover 102; the marine drilling suction anchor further comprises a drain pipe 108, a pump joint 109, an exhaust pipe 110 and an exhaust valve 111, wherein one end of the drain pipe 108 is connected with the drain hole 106, the other end of the drain pipe is connected with the pump joint 109, one end of the exhaust pipe 110 is connected with the drain hole 106, and the other end of the exhaust pipe 110 is connected with the exhaust valve 111. The design of the drain hole 106, the drain pipe 108 and the pump connector 109 can pump out the water in the inner cavity of the suction anchor cylinder 101; the gas in the inner cavity of the suction anchor cylinder 101 can be released through the arrangement of the drain hole 106, the exhaust pipe 110 and the exhaust valve 111.

The ocean drilling suction anchor comprises two sleeve assemblies 104, the pipe orifices at the lower end parts of the two sleeve assemblies 104 are coplanar with the avoidance opening 113 at the bottom of the suction anchor cylinder 101, and the two sleeve assemblies 104 are arranged along the axis direction of the suction anchor cylinder 101. The provision of two casing assemblies 104 may provide two drilling stations. Further, the ocean drilling suction anchor further comprises a reinforcing rib plate 103, one end of the reinforcing rib plate 103 is connected with the inner wall of the suction anchor cylinder 101, and the other end of the reinforcing rib plate 103 is connected with the sleeve assembly 104; and/or the reinforcement rib 103 is connected at one end to one of the sleeve assemblies 104 and at the other end to the other sleeve assembly 104. The provision of the stiffening ribs 103 provides greater stability between the sleeve assemblies 104 and between the suction anchor cylinder 101.

Embodiment two:

a marine drilling suction anchor as shown in fig. 4, embodiment two differs from embodiment 1 in that the lower end of the surface conduit 205 is gradually deviated from the upper end axis of the surface conduit from top to bottom, and the pre-inclined section includes a pre-inclined portion of the lower end of the surface conduit 205 and a pre-inclined portion of the lower end of the pre-inclined sleeve 203. The upper end pipe orifice of the surface conduit 205 is provided with a low-pressure well head 201, the low-pressure well head 201 is higher than the upper surface of the suction anchor cylinder 101, the upper end pipe orifice of the pre-inclined sleeve 203 is provided with a high-pressure well head 202, the high-pressure well head 202 is higher than the upper end pipe orifice of the pre-inclined sleeve 203, and the high-pressure well head 202 and the low-pressure well head 201 are mutually matched to form an external connecting port. Further, the inner wall of the low-pressure wellhead 201 is further formed with a mounting groove, the sleeve assembly 104 further comprises a mounting tooth block arranged in the mounting groove, the mounting tooth block is sleeved at the upper end of the pre-inclined sleeve 203, the upper end of the pre-inclined sleeve 203 and the upper end of the surface conduit 205 are fixedly connected through the mounting tooth block, a cement layer 302 is arranged between the outer side wall of the lower end of the pre-inclined sleeve 203 and the inner side wall of the lower end of the surface conduit 205, and high-strength cement is generally filled in the cement layer to fix the lower end of the pre-inclined sleeve 203 and the lower end of the surface conduit 205. Further, the height of the lower end nozzle of the pre-inclined sleeve 203 is H1, the height H2 of the lower end nozzle of the surface conduit 205, the height H3 of the bottom avoidance opening 113 of the suction anchor cylinder 101, H3-50mm is less than or equal to H1 and less than or equal to h3+50mm, H3-50mm is less than or equal to H2 and less than or equal to h3+50mm, and h1=h2=h3 generally, that is, the lower end nozzle of the pre-inclined sleeve 203, the lower end nozzle of the surface conduit 205 and the bottom avoidance opening 113 of the suction anchor cylinder 101 are coplanar.

Compared with the first embodiment, the second embodiment is more suitable for wellhead establishment and oil gas development of underwater soft stratum, the lower soil intensity reduces the penetration resistance caused by the pre-inclination of the conduit, the pre-inclination structure with a larger angle enables the drilling string to approach 90 degrees in a shorter vertical depth range, the problem that shallow storage is difficult to develop is solved, and the flexibility of development is greatly increased.

Embodiment III:

in an embodiment of the application, a method of drilling is also provided, and generally includes installation of a suction anchor for marine drilling, and drilling of shallow deep sea by a drilling system. Taking two sets of sleeve assemblies as examples, the method comprises the following steps:

step 100: the marine borehole suction anchor is run in installed and inspected.

Step 200: the drilling assembly is run into the well completion from the first casing assembly, and the first casing assembly and the oil recovery well drilled therein form a first wellhead.

Step 300: and (5) lifting out the drilling tool assembly and the underwater blowout preventer, and transferring to a second casing assembly.

Step 400: and (3) running a drilling tool assembly from the second casing assembly to perform well drilling operation, wherein the second casing assembly and the oil production well drilled therein form a second wellhead.

Step 500: installing an underwater Christmas tree and putting into production.

And installing a suction anchor for ocean drilling. Step S1, the ocean drilling suction anchor is moved downwards to avoid the opening 113, the lower end of the ocean drilling suction anchor is placed in a deep sea shallow layer, the pre-inclined section of the sleeve assembly is inserted into the deep sea shallow layer, and the drainage mechanism and the exhaust mechanism respectively exhaust gas and liquid in the cylinder cavity. The method specifically comprises the following steps:

the gas in the inner cavity of the suction anchor cylinder 101 can be discharged through the arrangement of the drain hole 106, the exhaust pipe 110 and the exhaust valve 111 in the water-entering process of the drilling suction anchor, and the water in the inner cavity of the suction anchor cylinder 101 can be pumped out through the design of the drain hole 106, the drain pipe 108 and the pump connector 109 in the stratum-penetrating process, so that the suction anchor penetrates into the soil layer, and the marine drilling suction anchor can be well installed on the deep sea shallow layer. Because the lower end of the pre-inclined casing 203 is arranged in advance in an inclined way, the drill bit of the drilling equipment is inclined to a certain degree at the suction anchor of the ocean drilling, so that the well inclination angle of the well hole is larger during drilling, and the deep sea shallow oil and gas resource is developed and utilized more fully.

The method specifically comprises the following steps:

in an embodiment of the application, the running installation and inspection of the marine drilling suction anchor comprises the steps of:

step 101: the marine drilling suction anchor is carried to a predetermined sea area using an engineering vessel.

Step 102: the suction anchor is hung into water by a crane which is connected with a hanging ring 112 on the suction anchor top cover 102, and the gas in the inner cavity of the suction anchor cylinder 101 is discharged through an exhaust valve 111 in the water entering process.

Step 103: and the anchor cap 102 is placed on the sea bottom with the upward dodging opening 113 facing downward.

Step 104: the underwater robot is operated to carry a suction pump connecting pump interface 109, the suction pump is started, water in the inner cavity of the suction anchor cylinder 101 is pumped out, and then the suction anchor penetrates into the soil layer. And stopping after the device is lowered to the preset position.

Step 105: the underwater robot is maneuvered to disengage the crane from the lifting loop 112 on the suction anchor cap 102 and recover the lifting rigging and suction pump.

Step 106: and the underwater robot is used for checking the installation parameters of the suction anchors of the marine drilling, so that the safety and stability of subsequent operation are ensured.

In an embodiment of the present application, the drilling assembly is lowered from the first casing assembly to perform a drilling and completion operation, comprising the steps of:

step 201: the drill assembly is connected to the first casing assembly and the drill assembly string is slid in along the drilling channel 207 of the pre-inclined casing 203.

Step 202: and (4) directional well drilling is carried out according to a program until the well depth is designed in the first stage.

Step 203: and performing well cementation operation, and installing the underwater blowout preventer to the first casing assembly according to a program.

Step 204: and continuing drilling until the drilling depth is finished, and performing well completion operation.

In one embodiment, using the drilling pattern as described in steps 201-204, seawater is used as the drilling fluid in step 202 to assist in cleaning cuttings during drilling and draining from the first casing assembly into the seawater. After the well section is drilled, the well is fixed, the underwater blowout preventer is installed to a first sleeve assembly in a descending mode, a closed loop is formed by combining a water isolation pipe, mud is used as drilling fluid in the subsequent drilling process, rock debris is cleaned in the drilling process, and the mud is discharged to a drilling platform mud pit from the upper end of the water isolation pipe.

In one embodiment, using the drilling pattern of steps 201-204, seawater is used as the drilling fluid in step 202, during drilling, the drilling fluid is sprayed from the drilling platform down the drill pipe from the bottom of the drill bit, and the rock chips carrying the drill are returned upward from the annular space between the drill pipe and the casing, and discharged from the first casing assembly into the seawater. In step 203, the well is cemented after drilling, and a subsea blowout preventer is installed in a first casing assembly, and the top of the subsea blowout preventer is connected to a sea surface drilling platform through a riser, thereby forming a closed loop. The continued drilling process at step 204 uses mud as drilling fluid, which is sprayed down the drill pipe from the drilling platform and out the bottom of the drill bit, with the drilled rock cuttings returning up the annular space between the drill pipe and the casing, and being discharged from the upper end of the riser to the drilling platform.

The well drilling mode is suitable for the situation without well control risk, and can effectively improve the well drilling efficiency.

In another embodiment, the underwater blowout preventer is first installed to the first casing assembly, a closed loop is formed by combining a water isolation pipe, mud is used as drilling fluid in all subsequent drilling processes, rock debris is cleaned in the drilling processes, and the rock debris is discharged to a drilling platform mud pit from the upper end of the water isolation pipe.

The drilling mode is suitable for the conditions of narrow stratum pressure window and well control risk, and can ensure the operation safety to a large extent.

In an embodiment of the application, the drill assembly and the subsea blowout preventer are lifted and transferred to the casing assembly No. two, comprising the steps of:

step 301: and performing temporary well sealing treatment on the first casing assembly.

Step 302: the drill assembly is pulled out, the subsea blowout preventer is unlocked at the first casing assembly and pulled out through the drill pipe.

Step 303: and operating the underwater robot to cover the first sleeve assembly with the wellhead cap.

In an embodiment of the present application, the drilling operation performed by the second casing assembly and the drilling assembly comprises the following steps:

step 401: the drill assembly is connected to the second casing assembly and the drill assembly string is slid in along the drilling channel 207 of the pre-inclined casing 203.

Step 402: and (4) directional well drilling is carried out according to a program until the well depth is designed in the first stage.

Step 403: and (4) performing well cementation operation, and installing an underwater blowout preventer to the second casing assembly according to a program.

Step 404: and continuing drilling until the drilling depth is finished, and performing well completion operation.

Step 405: and (3) lifting out the drilling tool assembly, unlocking the underwater blowout preventer at the second casing assembly and lifting out through the drill rod.

In an embodiment of the application, installing and putting into production an underwater christmas tree specifically comprises the following steps:

step 501: and installing the underwater Christmas tree on the second sleeve assembly.

Step 502: and operating the underwater robot to communicate the first sleeve assembly with the second sleeve assembly.

Step 503: and (5) putting into production according to the production program.

Specifically, the underwater robot is controlled to be connected with the discharge hole of the wellhead cap of the first sleeve assembly and the one-way input valve of the underwater christmas tree through a high-pressure pipeline, and the produced fluid of the first sleeve assembly is converged into the underwater christmas tree through the pipeline and is extracted together with the produced fluid of the second sleeve assembly.

According to the method for installing the suction anchor in the ocean well and the matched drilling method, the two wellheads can be installed simultaneously, the drilling efficiency is improved, the combined production of the produced fluids of the two wells is realized based on the matched drilling method, and the double production is achieved under the cost of one production system. And can provide a foundation for the joint development of various marine oil and gas resources so as to improve the economic benefit.

In the present application, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description of the terms "preferred embodiment," "further embodiment," "other embodiments," or "specific examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.

Claims (10)

1. The suction anchor for the marine drilling is characterized by comprising a suction anchor cylinder, a sleeve assembly, a drainage mechanism and an exhaust mechanism; the drainage mechanism and the exhaust mechanism are communicated with the cylinder cavity and are respectively used for discharging gas and liquid in the cylinder cavity; the suction anchor cylinder body is axially provided with a cylinder cavity, and the bottom of the suction anchor cylinder body is provided with an avoidance opening communicated with the cylinder cavity; the sleeve assembly is arranged along the axial direction of the suction anchor cylinder body, the sleeve assembly is provided with a drilling channel penetrating through the upper end and the lower end of the sleeve assembly, the upper end of the sleeve assembly penetrates through the top wall of the suction anchor cylinder body, the upper end of the sleeve assembly extends upwards compared with the upper surface of the suction anchor cylinder body, the upper end of the sleeve assembly is also provided with a drilling installation mechanism, the installation mechanism is positioned outside the suction anchor cylinder body, the drilling installation mechanism is used for being detachably connected with a drilling system and installing the drilling system to the upper end of the sleeve assembly, and the drilling channel is used for the telescopic movement of a drilling tool assembly of the drilling system and the flow of drilling fluid of the drilling tool assembly; the lower end of the sleeve assembly is provided with a pre-inclined section close to the avoidance opening, and the pre-inclined section gradually deviates from the axis of the sleeve assembly from top to bottom.

2. The marine drilling suction anchor of claim 1, wherein the sleeve assembly comprises a surface conduit mounted on the base plate barrel and a pre-inclined sleeve disposed within the surface conduit, the axis of the surface conduit and the axis of the pre-inclined sleeve both being adapted to the axis of the base plate barrel, the height of the lower end nozzle of the pre-inclined sleeve and the height of the lower end nozzle of the surface conduit both being matched to the height of the relief opening;

the pre-inclined section is formed by gradually deviating from the axis of the surface layer catheter from top to bottom at the lower end of the pre-inclined sleeve; or the pre-inclined section is formed by gradually deviating the same side of the axis of the surface layer catheter from top to bottom from the lower ends of the pre-inclined sleeve and the surface layer catheter.

3. The marine drilling suction anchor of claim 2, wherein the mounting mechanism comprises a low pressure wellhead and a high pressure wellhead; the low-pressure wellhead is arranged at the upper end pipe orifice of the surface layer conduit, and the high-pressure wellhead is arranged at the upper end pipe orifice of the pre-inclined sleeve.

4. The marine drilling suction anchor of claim 1, wherein the marine drilling suction anchor is used for deep sea shallow drilling with an earthen surface; at least two sleeve assemblies are arranged along the axle center of the sleeve assemblies.

5. A method of drilling comprising a drilling system and the marine drilling suction anchor of claim 1; the drilling process comprises the following steps:

s1, enabling the marine drilling suction anchor to move downwards so as to avoid an opening, enabling the lower end of the marine drilling suction anchor to be placed in a deep sea shallow layer, enabling a pre-inclined section of the sleeve assembly to be inserted into the deep sea shallow layer, and respectively discharging gas and liquid in the cylinder cavity by a water discharging mechanism and an air discharging mechanism;

s2, connecting a drilling system with a drilling installation mechanism to enable the drilling system to be installed at the upper end of the sleeve assembly, enabling drilling fluid provided by the drilling system to circularly flow between a drilling channel of the sleeve assembly and the drilling system, enabling a drilling tool assembly of the drilling system to stretch and retract in the drilling channel of the sleeve assembly, and enabling the drilling tool assembly and the drilling fluid to be matched to drill deep sea shallow layers.

6. The drilling method of claim 5, wherein in step S2, the drilling system further comprises a drilling platform, wherein during drilling, seawater is used as drilling fluid, the drilling fluid is sprayed from the drilling platform downwards along the drill rod of the drilling tool assembly from the bottom of the drill bit to flush the well, and then the drilling fluid is discharged upwards from the annular space between the drill rod and the sleeve from the sleeve assembly to the seawater, and the drilling system drills to the first stage design well depth;

the first stage designs well cementation after well deep drilling, and installs the underwater blowout preventer to the sleeve assembly in a descending way, the top of the underwater blowout preventer is connected to a sea surface drilling platform through a marine riser, thereby forming a closed loop, continuing drilling until the target oil extraction well is completed, and adopting mud as drilling fluid in the continuous drilling process.

7. The drilling method of claim 6, wherein at least two of the casing assemblies are used for drilling wells, the drilling system respectively forming at least two target oil recovery wells through the casing assemblies, and the target oil recovery wells and the corresponding casing assemblies forming at least two wellheads for oil recovery.

8. The method of drilling as recited in claim 7 wherein the wellhead includes at least a first wellhead and a second wellhead, the second wellhead having a tree installed therein and the second wellhead and the first wellhead being in communication via a high pressure line.

9. The drilling method of claim 8, wherein the christmas tree is installed and the high pressure pipeline is installed by an underwater robot.

10. Drilling method according to any of claims 5 to 9, wherein the marine drilling suction anchor installation parameters are also checked by means of an underwater robot.