A method of construction for offshore pipeline butt joining

Abstract

A construction method for offshore pipeline butt joint, comprising the following steps: determining whether the drill bit of the directional drill has drilled to the emergence point; after the drill bit drills to the emergence point, preliminarily detecting the emergence area of the drill bit by using a magnetic force detection device; inflating the channel reserved for the drill rod of the directional drill by an air compressor at the starting point of the directional drill; when the bubbles come out from the head of the drill bit, a diver dives to find the accurate position of the drill bit and marks it; the drill bit continues to drill forward until the drill bit emerges from the sea level; the pipe pulling head of the bottom pipe laying is pulled from the side far away from the directional drill to the area near the drill bit, and then is lifted by the crane on the barge connection platform; the butt joint of the bottom pipe laying and the drill bit is completed on the barge connection platform, and then the bottom pipe laying and the drill bit after butt joint are lowered to the designated position. The construction method for offshore pipeline butt joint can quickly complete the butt joint operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of offshore water pipeline laying, in particular to a construction method for offshore pipeline butt joint. BACKGROUND

[0002] In the process of laying water pipeline to the island in the sea through the channel, when different construction technologies are used for submarine pipeline laying construction, the water pipeline laying is carried out from both sides of the coast respectively by using two technologies, when the pipeline laying construction reaches the specified butt joint position, the butt joint operation on the sea is needed, and the offshore pipeline laying is difficult to realize the fast and accurate pipeline butt joint operation due to the complex submarine topography and surrounding environmental conditions.

[0003] Taking a submarine water pipeline project in Wenzhou Dongtou District as an example, the pipeline laying is a combination of directional drilling and bottom drag, when the butt joint of the pipeline is carried out on the sea, the directional drilling is drilled from the starting point on the coast, and is always below the submarine mud surface by about 15 meters, when the directional drilling reaches the unearthing point, the drag pipe head of the bottom drag is connected with the drill bit of the directional drilling, and finally the pipeline on the side of the bottom drag is back dragged with the drill bit of the directional drilling, so as to realize the laying of the pipeline.

[0004] Due to the long distance of the pipeline laying area in the beach section, large tidal range, short construction period, crossing the main channel, and the existence of submarine optical cable and breeding area in the laying area, the unearthing point of the drill bit of the directional drilling needs to be accurately positioned, due to the long construction distance of the directional drilling in the project, about 2.8km, there is a certain deviation in the positioning accuracy of the drill rod positioning device of the directional drilling equipment itself, and the drill bit of the directional drilling may be distributed below the submarine mud surface when it reaches the unearthing point, so the conventional detection instrument is difficult to accurately determine the unearthing point of the drill bit of the directional drilling, which increases the difficulty of the butt joint of the pipeline.

[0005] Since the project is offshore pipeline laying construction, there are channels and water aquaculture areas in the surrounding sea area of the pipeline laying, the channel is not interrupted, the laying area is beach sea area, the water quality is relatively turbid, and there is more silt soil on the seabed, when the drill bit reaches the unearthing point, if the drill bit directly continues to drill out from the silt surface, the position is difficult to be positioned in a short time (if other measurement equipment is not used, only the positioning system of the directional drilling itself is used for positioning, the positioning is not accurate, and the error is large; if other measurement equipment is used, the range is large, and about 2-3 days of time is needed, which leads to a large warning area, long channel closure time and unpredictable influence and danger to the water aquaculture area (since it is difficult to control the accuracy of the initial drilling of the drill bit, it is more stable to be below the silt surface when reaching the unearthing point). SUMMARY

[0006] The technical problem solved by the present application is to provide a construction method for offshore pipeline butt joint, aiming at the situation that the drilling point of the drill bit is below the seabed silt surface when the directional drilling and bottom drag combined pipe laying construction is adopted, the detection instrument is difficult to accurately detect, the drilling point of the directional drill bit can be quickly and accurately found, the butt joint of the pipeline is realized, and the influence of long time construction on the channel traffic and offshore aquaculture area caused by searching for the drill bit is avoided.

[0007] To solve the above technical problem, the technical solution adopted by the present application is:

[0008] A construction method for offshore pipeline butt joint, comprising the following steps:

[0009] Step 1: determining whether the drill bit of the directional drill has drilled to the drilling point;

[0010] Step 2: when the drill bit drills to the drilling point, the drilling area of the drill bit is preliminarily detected by using a magnetic force detection device;

[0011] Step 3: the channel reserved for the drill rod of the directional drill is inflated by the air compressor at the starting point of the directional drill; when the bubbles come out from the head of the drill bit, the accurate position of the drill bit is found by the diver and marked;

[0012] Step 4: the drill bit continues to drill forward until the drill bit is exposed to the sea level; the pipe dragging head of the bottom drag pipe laying is dragged to the area near the drill bit from the side far away from the directional drill, and then is lifted by the crane on the barge connection platform;

[0013] Step 5: the butt joint of the bottom drag pipe laying and the drill bit is completed on the barge connection platform, and then the connected bottom drag pipe laying and drill bit are placed to the designated position.

[0014] In step 1, whether the drill bit has drilled to the drilling point is determined by the mud pressure, thrust and drill rod length; when the drill bit drills to the drilling point, the drill bit is located above the seabed surface and in the silt layer below the seabed silt surface, and the distance between the drill bit and the seabed silt surface is 1 m to 2 m.

[0015] In step 2, when the drill bit drills to the drilling point, the drill bit is located above the seabed surface and below the seabed silt surface, the barge connection platform measures back and forth multiple times according to the preliminarily determined sea area of the pipeline and perpendicular to the pipeline direction, the line spacing is 15 m, and the data information of each measurement is recorded.

[0016] In step 2, before detection, the magnetic force detection device is kept apart from the barge connection platform, the GPS positioning instrument is connected with the magnetic force detection device, and the receiver of the GPS positioning instrument is fixedly installed at the streamer towing point of the magnetic force detection device.

[0017] In step 2, before detection, the streamer of the magnetic force detection device is bound with a floating ball.

[0018] In step 3, when the air compressor is inflated, the drill bit slowly drills into and penetrates the silt layer to extend to the seabed silt surface.

[0019] In step 3, when the diver descends, the distance and direction of the drill bit to the water surface are further determined to obtain the accurate position of the drill bit, and the drill bit is bound with a lifting belt.

[0020] In step 3, the specific time of inflation is determined according to the pressure during drilling, and inflation is started when the seabed silt layer is about to be exposed.

[0021] In step 5, after the drill bit is connected with the pipe head of the bottom drag pipe and placed, the directional drilling is dragged to the bottom drag pipe, the bottom drag pipe is guided to the right side of the directional drilling position, and the pipeline laying is completed.

[0022] A construction method for offshore pipeline butt joint, comprising the following steps:

[0023] The present application provides a construction method for offshore pipeline butt joint, which has the following technical effects:

[0024] 1) In view of the complex environmental conditions such as marine aquaculture area and channel passage, when the drill bit of the directional drill reaches the unearthing point, the drill bit of the directional drill drills out of the seabed surface, but there is still a certain thickness of silt on the surface due to the fact that it is still in the beach area, on the basis of the positioning of the directional drill itself, the magnetic field generated by the magnetic force detection device is measured multiple times along the pipe laying direction, on the one hand, the area where the drill bit is located can be preliminarily obtained, and the positioning interval of the drill bit is reduced; on the other hand, through the measurement of the magnetic force detection device, the running track of the drill bit of the directional drill can be further understood, and the position of the final unearthing point can be determined, thereby further improving the accuracy of the unearthing point of the drill bit of the directional drill below the silt surface.

[0025] 2) On the basis of the positioning of the magnetic force detection device, the channel reserved for the drill rod of the directional drill is inflated by the air compressor at the starting point of the directional drill, the bubble of the drill bit of the directional drill can directly and accurately position the unearthing point of the drill bit of the directional drill, the positioning of the unearthing point of the drill bit of the directional drill can be greatly shortened, and the connection efficiency between the pipe head of the bottom drag pipe and the drill bit of the directional drill can be improved.

[0026] 3) After the drill bit of the directional drill confirms the unearthing point and the track, the pipe head of the bottom drag pipe and the drill bit of the directional drill are respectively salvaged and lifted to the barge connection platform, the quick connection of the directional drill and the pipe head is carried out on the platform, and the risk of offshore pipeline butt joint is reduced.

[0027] 4), the prior art encountered drill bit to reach the point of unearthing, if the construction environment of the project is not very complex, there is no channel and aquaculture area, when the drill bit is in the silt, the drill directly drills out the silt interface, relies on the positioning device system of the directional drilling itself and the diver to determine the unearthing point of the pipeline, which needs 2-3 days; the method can greatly shorten the time, and the position of the pipeline can be determined and the butt joint can be realized within 1 day, the influence of the surrounding complex environment is reduced; especially in the face of complex environment such as the existence of roadway and aquaculture area, the effect is particularly obvious. BRIEF DESCRIPTION OF DRAWINGS

[0028] The present application will be further described below in combination with the drawings and examples:

[0029] Figure 1 It is a schematic diagram of the drill bit of the directional drilling drilling to the unearthing point (the sea bottom silt layer is not drawn).

[0030] Figure 2 It is Figure 1 a detailed view of the drill bit located at the unearthing point.

[0031] Figure 3 It is a schematic diagram of the air bubble blowing by the air compressor in the present application (the sea bottom silt layer is not drawn).

[0032] Figure 4 It is a schematic diagram of the butt joint of the bottom towed pipe and the drill bit in the present application (the sea bottom silt layer is not drawn).

[0033] Figure 5 It is a schematic diagram of the directional drilling back dragging the bottom towed pipe in the present application (the sea bottom silt layer is not drawn).

[0034] In the figure: barge connection platform 1, directional drilling 2, drill bit 3, drill rod 4, magnetic detection equipment 5, floating ball 6, bottom towed pipe 7, pulley 8, ground a, sea level b, sea bed surface c, soil entry point d, unearthing point f, butt joint point g, sea bottom silt surface v. DETAILED DESCRIPTION

[0035] As Figures 1-4 shown, a construction method for offshore pipeline butt joint, comprising the following steps:

[0036] Step 1: The drill bit 3 of the directional drilling 2 determines whether it has drilled to the unearthing point according to the mud pressure, thrust, drill rod length, etc. When the drill bit 3 drills to the unearthing point, the drill bit 3 is located above the sea bed surface c and in the silt layer below the sea bottom silt surface v, and the distance between the drill bit 3 and the sea bottom silt surface v is 1 m-2 m. At this time, the magnetic detection equipment (magnetic force meter) is used to detect the unearthing position of the drill bit 3.

[0037] Step 2: In order to reduce the influence of magnetic objects such as generators on the detection accuracy of the magnetometer at the barge connection platform 1 (survey ship), a professional survey ship is used, and the magnetometer is placed 20 meters away from the tail of the survey ship. The GPS positioning instrument is connected with the magnetometer, and the plane position is positioned by the GPS positioning instrument. In order to reduce the positioning error of the measurement data, the GPS receiver is fixedly installed at the towing point of the magnetic detection equipment 5 (magnetometer); in order to avoid the sinking of the magnetic detection equipment into the seabed, the floating ball 6 is tied near the cable of the magnetometer.

[0038] Step 3: The survey ship measures multiple times back and forth in the sea area preliminarily determined by the pipeline, and the measuring line spacing is 15m. The data information of each measurement is recorded.

[0039] Step 4: The preliminary position information of the drill bit 3 is determined by using the magnetic detection equipment, and the drill bit 3 is preliminarily determined to be within the magnetic detection area L (the range of area L is 10-15m). The drill bit 3 mainly relies on the magnetic detection equipment under the silt layer, and when the preliminary position is determined, the drill bit 3 slowly drills into and penetrates the silt layer to extend out of the silt surface v of the seabed. At the same time, the channel reserved by the air compressor for the drill rod 4 of the directional drill 2 at the starting point is inflated.

[0040] When the bubbles come out from the head of the drill bit 3 of the directional drill 2, the diver dives to find the drill bit 3, further judges the distance and direction of the drill bit to the water surface, and obtains the accurate position of the drill bit 3. At the same time, the hoisting belt of the drill bit 3 is tied, which is convenient for subsequent hoisting and docking of the drill bit 3.

[0041] In step 4, the specific time of inflation is determined according to the pressure during drilling. The inflation is started when the seabed silt layer is about to be exposed.

[0042] Step 5: The drill bit 3 of the starting point directional drill continues to drill forward until the drill bit 3 is exposed above the sea level b. The pipe head of the bottom drag pipe 7 is towed to the area near the drill bit 3 by the tugboat, and then the pipe head of the bottom drag pipe 7 is lifted by the crane on the barge connection platform 1. The drill rod, the drill tool, the divider and the bottom drag pipe 7 (main pipeline) are connected on the barge connection platform 1. The connected bottom drag pipe 7 and the drill bit 3 are placed to the designated position by the crane on the barge connection platform 1. Thus the docking is completed.

[0043] After the drill bit 3 and the pipe head of the bottom drag pipe 7 are docked and placed, the directional drill 2 drags the bottom drag pipe 7 to the right side of the position of the directional drill 2, and the pipeline laying is completed.

Claims

1. A method of construction for offshore pipeline butt joining, characterised in that, The method comprises the following steps: Step 1: determining whether the drill bit (3) of the directional drill (2) has drilled to the emergence point; Step 2: after the drill bit (3) drills to the emergence point, preliminarily detecting the emergence area of the drill bit (3) by using a magnetic detection device (5); Step 3: inflating the channel reserved for the drill rod (4) of the directional drill (2) at the starting point of the directional drill (2) by using an air compressor; when the bubbles come out from the head of the drill bit (3), a diver dives to find the accurate position of the drill bit (3) and makes a mark; Step 4: the drill bit (3) continues to drill forward until the drill bit (3) emerges from the sea level; the pipe head of the bottom towed pipe (7) is towed to the area near the drill bit (3) from the side far away from the directional drill (2) and is hoisted by the crane on the barge connection platform (1); Step 5: completing the butt joint of the bottom towed pipe (7) and the drill bit (3) on the barge connection platform (1), and then lowering the bottom towed pipe (7) connected with the drill bit (3) to the designated position.

2. A method of construction for the butt joining of offshore pipelines according to claim 1 characterised in that: In step 1, whether the drill bit (3) has drilled to the emergence point is determined by the mud pressure, the thrust, and the length of the drill rod; when the drill bit (3) drills to the emergence point, the drill bit (3) is located above the sea bed and below the sea bottom silt, and the distance between the drill bit (3) and the sea bottom silt is 1m to 2m.

3. A method of construction for the butt joining of offshore pipelines according to claim 1 characterised in that: In step 2, when the drill bit (3) drills to the emergence point, the drill bit (3) is located above the sea bed and below the sea bottom silt, the barge connection platform (1) measures back and forth multiple times according to the preliminarily determined sea area of the pipeline and perpendicular to the pipeline direction, the distance between the measuring lines is 15m, and the data information of each measurement is recorded.

4. A method of construction for the butt joining of offshore pipelines according to claim 1 characterised in that: In step 2, before detection, the magnetic detection device (5) is kept apart from the barge connection platform (1), a GPS positioning instrument is connected with the magnetic detection device (5), and the receiver of the GPS positioning instrument is fixedly installed at the tow point of the tow cable of the magnetic detection device (5).

5. A method of construction for the butt joining of offshore pipelines according to claim 1 characterised in that: In step 2, before detection, the tow cable of the magnetic detection device (5) is bound with a float (6).

6. A method of construction for the butt joining of offshore pipelines according to claim 1 wherein: In step 3, when the air compressor inflates, the drill bit (3) slowly drills and penetrates the silt layer to extend out of the sea bottom silt.

7. A method of construction for the butt joining of offshore pipelines according to claim 1 wherein: In step 3, when the diver dives, the distance of the drill bit to the water surface and the trend are further judged, the accurate position of the drill bit (3) is obtained, and the drill bit (3) is bound with a hoisting belt.

8. A method of construction for the butt joining of offshore pipelines according to claim 1 wherein: In step 3, the specific time of inflation is determined according to the pressure during drilling, and the inflation is started when the sea bottom silt layer is about to be penetrated.

9. A method of construction for the butt joining of offshore pipelines according to claim 1 wherein: In step 5, after the drill bit (3) is butt jointed with the pipe head of the bottom towed pipe (7) and placed, the directional drill (2) pulls back the bottom towed pipe (7) to lead the bottom towed pipe (7) to the position of the right directional drill (2), and the pipeline laying is completed.

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