JPS593626B2 - Semi-submerged housing unit station station - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semi-submersible oil tank used in a semi-floating state to extract and store oil offshore.
The present invention relates to an oil extraction/storage unit/station of the ubmersible type and an oil extraction/storage method.

Currently, the extraction of crude oil through offshore drilling is shifting from extraction in relatively shallow waters near the coast to extraction in deeper waters.

However, when extracting oil from deep waters, conditions are disadvantageous due to poor sea surface conditions due to waves and other factors. In the case of oil extraction near the coast where the water is relatively shallow, a fixed platform for drilling and treatment of the oil can be installed at that location very simply and economically. The oil can then be sent from that location to an oil refinery on the coast, where it undergoes further processing such as refining, or the oil can be transported from that factory. These days, in many cases, crude oil
eOil) is transferred directly to an oil tanker or barge.

Oil storage tanks are also located at some extraction locations. These tanks may be fixed, large-capacity oil storage units/stations erected on the seabed, floating on the surface of the sea, or consisting of floating tanks located near the surface of the sea. When oil is extracted in deep waters off the coast, drilling, extraction, and storage of crude oil becomes considerably difficult.

To date, no good method has been found to overcome this difficulty. In such offshore waters,
It is always impractical to lay pipelines to oil refineries on the coast, both technically and economically. Additionally, installing a submarine tank system that is completely submerged below the sea surface requires local and remote control, which is technically not easy. Water depth and sea surface conditions are major obstacles to fixing a platform on the seabed and installing a submarine tank. In such circumstances, a floating platform, i.e. a platform consisting of a submersible or semi-submersible floating tank with a small surface area and a relatively large internal capacity, is suitable. . However, the structures of tanta seen to date do not have sufficient resistance to the action of waves. Therefore, semi-submersible platforms are suitable for use in experimental drilling offshore, but
Since the conventional type lacks stability, it has been difficult in practice to store the crude oil pumped from an oil well. In addition, stations equipped with this platform can be used for multiple purposes such as oil extraction and storage, while maintaining position and maintaining a constant flow of water (Draft).
t) was inappropriate because it could not be sufficiently maintained. Further, the station was not configured to be able to move freely to a predetermined position. As a result, offshore drilling, extraction and storage can be carried out in one unitary station that can be used at any depth and regardless of the geological structure of the seabed. It was hoped that new technology could be developed.
Furthermore, the unit station is capable of extracting, storing, and transporting oil without causing oil leakage, with minimal power, and without the use of many auxiliary equipment, and is capable of connecting to large tankers. There was a need for something that had adequate storage capacity and could be manufactured at an economical cost. The present invention is applicable to offshore drilling, oil extraction,
The present invention also aims to provide a new method for oil storage and a semi-submersible oil extraction/storage unit/station therefor. The method according to the present invention and the preferred specific structure of the unit station will first be briefly described. The oil extraction/storage unit/station according to the present invention includes a boat-shaped body having a plurality of liquid-tight tanks. The tanks are fixedly attached in parallel to each other to form a fluid storage vessel whose upper and lower surfaces are liquid-tight. A strut is fixed to the upper surface of the central portion of the hull, and a platform is supported on the strut. The platform is designed to remain above water even when the hull is submerged to a predetermined water level. A plurality of column-shaped stabilizers are connected to each other by a universal joint as a connecting means, and are provided at the outer circumferential end of the boat-shaped body in an upright state at a distance from each other. These stabilizers serve to provide a restoring force to the hull in response to changes in the inclination angle of the hull, and also to provide a force for returning the hull to an upright position. The plurality of tanks include a first tank containing air and oil;
and a second group of tanks containing water and oil.

Each tank is equipped with fluid inlet and outlet connectors for introducing and discharging water, air, or oil. Additionally, fluid control means are provided for introducing and discharging fluid into each tank. First, in the first operation, the unit stage tank is towed to a desired offshore position, and at that point, a predetermined amount of seawater is introduced into the second group of tanks as ballast.

This reduces the buoyancy of the unit station and causes the hull, struts and stabilizers to sink to a predetermined water position. The hot water is placed on the top of the hull below the hot water of any ocean-going tanker. At this predetermined water level, oil is drawn into and stored in all tanks via the fluid control means. This oil is pumped through an oil distribution manifold to a water tank and an air tank. Therefore, water and air are released from each tank by the amount of oil that has been pumped in. The amount of oil distributed to the first and second groups of tanks corresponds to the amount necessary for the hull to maintain the same buoyancy, tightness position and attitude. The stored oil is then loaded from the tank via a central column and platform into a tanker waiting at sea, for example, by means of a pump drive. In this way, when oil is simultaneously pumped out of the first and second groups of tanks, air and water are instead drawn into the tanks. The air and water are introduced in exactly the proportions necessary to maintain a predetermined tight water position in the hull. It has been found that a good volume change ratio between the first and second groups of tanks with and without oil is about 2:9. As for the structure of the hull (a first group of tanks for air is arranged around a central pillar).

A second group of tanks containing water and oil is arranged concentrically around the first group of tanks. and,
Bulkhead-like supports are arranged radially to keep each tank in place. The upper platform is centrally supported by columns and contains equipment such as pumps, prime movers, and separators. The hull can be accessed from the platform via struts. On the upper platform, drilling equipment for offshore drilling will be installed. death,
After the excavation is complete, it can be removed and a retractable boom (BOOM) installed. This boom serves to support an oil delivery line that projects outward from the outer end of the tank for connection to a tanker, barge, or the like. Crude oil extracted from an oil well on the seabed enters a flexible rigid pipe (riser) connected to the proximal end of the central column, passes through a separator that separates gas and water, and is stored by fluid control means. sent to the tank.

The plurality of stabilizers protrude upwardly from the surface of the hull, with their tips extending just above the normal water surface position. These stabilizers exert an upward or downward force on the hull when the horizontal position changes. However, these stabilizers are not wave followers that respond to wave height. Additionally, these stabilizers may cause the ship to collide with floating ice or work boats. However, since these stabilizers are connected to the hull by a universal joint, they can rotate freely. Therefore, even if there is a collision, it will not suffer the same damage as a fixed container-like facility. These stabilizers also have stabilizing means inside them. That is, the means is provided inside and above the stabilizer and includes a tank filled with liquid and having a flow restriction member. And this means lengthens the normal period of vibration of the stabilizer. The means also serve to de-synchronize the period of the stabilizer with the period of the waves, so that the influence of the loads transmitted to the hull via the universal joint is reduced. Therefore, the stability of the submerged hull is even higher. Thus, in a specific configuration of the present invention, a semi-submersible ship consisting of a number of tanks equipped with a central column, a platform, and a column stabilizer is used for drilling, oil extraction, and oil storage. A hull form is provided which is sufficiently submerged to avoid being adversely affected by waves.

Since the hull has a low center of gravity and sufficient weight, it does not synchronize with the wave cycle. In addition, since the hull is equipped with a sufficiently large anchor and is dropped below the sea surface, the stability of the hull is further ensured, and swaying, pitching, rolling, etc. of the hull are suppressed as much as possible. It will be done. Each tank of the hull is completely enclosed by means for separating the oil from the water discharged from the tank;
It can be moved to another location in the event of a fire or explosion. In addition, the hull stores oil at a sufficient depth and has sufficient strength, so even in the unlikely event of a collision, there will be no oil leakage or tank rupture. The risk of such is extremely low. Hereinafter, the present invention will be explained in more detail according to embodiments shown in the drawings.

In the embodiments shown in FIGS. 1 to 4, the harvesting and
Storage unit station 10 includes a submersible fluid storage hull 12 having a plurality of separate tanks.

One end of the support column 16 is fixed to the center of the earth surface of the boat body 12. A platform 18 is supported at the upper end of the column 16. A number of independent column-like stabilizers 14 are fixed to the hull 12 by universal joints 22 which are connecting means. Each tank surrounded by the hull 12 has a fan shape.

The tanks are divided into a first group of tanks 80 containing air and oil, and a second group of tanks 84 containing water and oil as ballast. Regarding the structure of the tank, the inner tank 80 of the first group has steel partition wall members 76, 77, 78 and an upper wall member 7.
9 and a bottom wall member 81. The partition wall-like member 76 projects radially toward the outer end of the boat body 12. Further, the other partition wall-like members 77 and 78 have a cylindrical shape,
The arc portion constitutes the outer end and inner end of the first group of tanks 80 located inside. The second group of tanks 84 on the outside are constructed of pre-stressed concrete. The upper and lower surfaces of the hull 12 are also made of concrete, as is the outermost arc-shaped outer end surface 86. In this way, the first group of tanks 80 is subjected to a pressure different from and greater than the pressure of the surrounding seawater.
It has a stronger structure than the second group of tanks 84 that accommodate seawater as ballast. The opening in the inner part of the hull 12 is formed by a strut-like member that stands concentrically within the cylindrical bulkhead-like member 77 . A shaft 20 is arranged within the column 16 .
The shaft 20 is supported by a rope support member 21.
Furthermore, a recovery tank 72, a large number of connecting pipes and lines, etc. are arranged on the support column 16, as will be described in detail later. As shown in FIGS. 2 and 4, a hosepipe 42 projects through a first group of turns 80. As shown in FIGS. A plurality of anchor chains 44 are connected to hose pipes 42 and air leaders (Fa
irlead) 40 to the side of the column and reach the platform ohm 18. A conventional anchor actuation mechanism on the platform 18, such as a video controller, controls each of the anchor chains 44. Each anchor chain serves to maintain the unit station at a desired location, ie, near the oil well 32 on the seabed 34.
The fluid control means consists of line 98 and manifold connector 100.

The connector 100 connects oil to each tank 84 of the second group.
It is meant to be taken into the body and taken out of it. Lines 106 cooperate with connectors 108 to draw seawater into and out of each tank 84 of the second group. Line 102 and connector 104 cooperate with line 102 to define an air vent through the surface of tank 84 to direct air to tank 84.
It functions to take it into the tank and extract it from the tank. Lines 110 and connectors 112 are provided to draw oil into and out of tank 80. As shown in FIGS. 4 and 10, lines 110, 98
is connected to the manifold 1 via flow control valves 138 and 136.
18 sections 119 and 121, respectively. The valve 136 is a check valve for controlling the flow rate, and its function will be explained in detail later. A plurality of lines 106 communicate with a recovery tank 72, which has lines 116 in direct communication with the surrounding seawater. The operation of introducing air and water as ballast into the tank and the operation of storing and pumping oil from the tanks 80, 84 will now be described.

Water line 116, collection tank 72 and line 106
It is taken into tank 84 via. Air is introduced into tank 80 via line 102, which constitutes an air vent. When oil is stored in each tank, the oil is first received into the source line 30 from an oil well 32 below sea level. The oil is passed through a separator 127 in the upper platform 18. This separator 127 separates water and gas from oil. The separated water and gas are line 1
28 and 130, respectively. The oil is then
It is passed through pump 132, valve 134 and line 124 to section 119 on one side of manifold 118. A portion of the oil flows through each flow control valve 136 and line 98 into the second group of tanks 84 .
Other oils are also supplied to manifold valves 123, the other side 121 of manifold 118, and each flow control valve 138.
, into each tank 80 via line 110. When the oil enters the tank 84, the water in the tank flows into the surrounding sea in line 106 in proportion to the volume of oil that has flowed into the tank.
, valve 137, collection tank 72 and line 116. The recovery tank 72 serves to recover oil from water released into the sea by sedimentation.
Air within the tank 80 is extracted to the outside through an air vent line 102. In order to pump out the stored oil, the booster pumps 120, 125 are activated, which causes oil to flow from each tank 80, 84 to each section 121, 119, line 122, valve 123 under the manifold.
The oil is then sent to the oil feed line J through the pump 126 located above. Booster pump 120, 12
5 serves to raise the oil to platform 18. In the above operation, each tank 8
The air and water within 0.84 are in proportions to maintain the buoyancy of the hull 12 at a desired value and the desired tightness of the hull 12 in seawater.

The volume relationship is such that when water and air are replaced with oil at a predetermined ratio of about 2:9, the hull 12 maintains a constant buoyancy and a tight water position. It is desirable that the volume of tank 80 and the volume of tank 84 be in a ratio of approximately 2:9. Manifold 118 section 1
As the oil is separated from the oil contained in the tank 80, approximately 2:
9 at the same rate. Valve 123 is a general term for several valves. Two manifolds de section 11
The line connecting 9 and 121 substantially relieves the flow restriction between both sections when valve 123 is opened.

Further, the valve 123 is controlled by a known control mechanism 200 via a lie 7173. In addition, tanks 80, 84
At the same time, it can also be filled with oil. This oil filling ratio is 122:9, which can be achieved by any suitable method. As a method of filling oil: For example, each tank 84
or by providing line 98 with a diameter sufficiently larger than line 110 to allow oil to flow through each rhino in a 9:2 flow rate relationship in tank 80; Alternatively, any suitable means for achieving the appropriate flow relationship may be used, such as controlling the flow rate through each valve 136, 138. The valve openings of valves 136, 138 are selectively controlled via respective control lines 204 or 171 by a known control mechanism 200, such as a central control unit. Such simultaneous flow distribution method can also be applied when oil is removed from each tank by pumps 120, 125 under the control of valves 136, 138 and valve 123. During the work of taking out oil from each tank 84, water is added to the line 11 in each tank to replace the oil in the tank 84.
6 by the normal water pressure generated by the water depth. Therefore: When pump 132 is not operating, the check valves of valves 136 in line 98 ensure that water is not flowing to each tank 84 and manifold 11.
8 to each tank 80 for air. In the operation of taking out oil from the tanks 80, 84 by driving the ports 120, 125, the check valve portion of the valve 136 is kept open so that the oil can flow back. There is a need. In this condition, valve 123 is closed to prevent water from flowing back through manifold 118 from tank 84 to tank 80. valve 136
, 138 are adjusted when controlling the flow rate. Sufficient oil pressure is generated by the operation of sending oil to the tank 84 by driving the pump 132, and water flows from the tank 84 to the valve 1.
37. The opening and closing operations of the check valve portion of valve 136 and opening and closing of valve 123 may be performed manually or by automatic control means via lines 171, 173 from a central valve control unit.
Valve 137 in line 106 controls the amount and flow rate of water entering tantaur 84. In FIG. 5, the volume of the water ballast tank 84 is 9 compared to the two air tanks 80.
The state in which the ratio of

Such an arrangement ensures that the proportions of water and air acting as ballast in the hull 12 and unit station 10 and oil are always correct for the normal inherent gravity forces of seawater and crude oil. A known detector 170 for detecting the interface between water and oil is disposed in each tank 84, and signal output information from the detector 170 is transmitted on line 2.
02 to the central valve control mechanism 200.
A probe 164 is provided within tank 80 to detect the air/water interface and provides signal output information to central valve control mechanism 200 via control line 204 . A central valve control mechanism 200 controls the flow rate through each valve 136, 138 via a return control line 204 to maintain the relative oil volumes in all tanks 80, 84 at proper values. Furthermore, since the positions of the tanks 80 and 84 are balanced under the control of the central valve control mechanism 200, the overall posture of the hull 12 and unit station 10 is also balanced. Each of the columnar stabilizers 14 is constituted by an elongated cylindrical columnar member. One end of the columnar member is
The partition wall member 76 is connected to the upper surface of the boat body 12 by a universal joint 22 at a position near the end thereof.
In FIG. 11, the universal joint is located at the base portion 1;! '90, which member is secured to the upper surface of the bulkhead member 76, recessed within a layer 96 of concrete. The U-shaped saddle member 90 supports a shaft 95 on which a connector 88 is provided. The connector 88 is connected to a connector 92 by an axis 94 perpendicular to the axis 95, and the connector 92 is fixed to the columnar stabilizer 14. The universal joint 22 allows the stabilizer 14 to freely link relative to the hull 12. The columnar stabilizer 14 has a plurality of vertically juxtaposed and sealed compartments.

The upper compartment is divided into a central volume portion 140 and an outer ring-shaped volume portion 144 by a plurality of partition members. 150.Also, the volume portion 1
At the center of 44 and at both ends thereof, a buttful member 146 formed of a cylindrical pipe is arranged. The buttful member 146 includes side volume portions 156, 157,
It functions to restrict the flow of liquid 152 between 158 and 159. This limiting action stabilizes the stabilizer 14 and reduces the load transfer from the stabilizer to the hull 12 via the universal joint 22. In this way, the stabilizer 14 actively maintains positional stability even as the water surface level changes by exploiting the free surface effect of the water. Air is admitted to the lower chamber 154. The buffful member 146 changes the period of the swing of the stabilizer 14 caused by the action of waves, and moves the stabilizer 14 to the universal joint 2.
This serves to further reduce the burden of the load acting on the
When operating the unit station 10, first,
Each tank 84 is filled with a predetermined amount of ballast via valve 137, thereby maintaining the desired water position of the hull 12.

Valve 135 is opened as necessary to release air or gas from each tank. In this situation, the sixth
As shown in the Figures and FIG. 7, the stabilizer 14 is at rest on the top surface of the hull 12, but it may also be in a restrained, immovable position. A suitable vessel 52, such as a tugboat, is connected to the hull 12 by a line 50 and a connector 48;
The unit station 10 is towed to a predetermined location by the tug. Once the unit station 12 reaches a predetermined location, it is anchored there.
Then, each valve 137 is opened and seawater flows into the tank 84.
can be fully incorporated within. The introduced seawater brings the unit station 10 into a predetermined steady state of buoyancy. The hull 12 is submerged to a predetermined deep water position. Here, the buoyancy of the strut 16 relative to the buoyancy of the hull 12 and stabilizer 14 serves to maintain the hull 12 in a constant water condition. Valve 37 is closed and anchor chains are dropped as many times as necessary to prevent cross flow of unit station 12. A rigging system 54 is provided on the platform 18 in which a digging cable system is threaded through the shaft 20. When the unit station 10 is changed from the drilling operation to the oil extraction and storage condition, the rigging mechanism 5 is used.
4 is removed and a source line 30 is attached to the oil well 32. Thereby, oil is taken into each tank 80, 84 via separator 127 and manifold 118. During this oil intake, water and air are discharged from each tank to maintain a constant level of water in the hull 12. Thereafter, when the oil stored in the tank of the hull 12 is to be sent out from the tank, the platform 1
A suitable boo 62 is installed on the 8. The boom 62 has a counterweight 66 and a positioning roller 64.
The oil delivery line 70 is connected to the pump 126 by an upper delivery connector housing 66 . The boom 62 allows the oil line 70 to fully reach the tanker 60. In addition, the tanker is attached to line 5 for tethering.
0 and connector 48 can be connected to the hull 12. Tanker 60 due to buoy 58 in the stern
is maintained relative to the unit station 10. Furthermore, the relative size of the boom 62 shown in FIG. 9 and the digging rope mechanism 54 shown in FIG. 8 is merely shown schematically and does not represent the actual size. Please note that. In practice, the boom 62 will project a sufficient length beyond the outer end of the hull 12. For example, the unit station 10 is 10
If the structure is designed to have the capacity to store 1,000,000 barrels of oil, the outer diameter of the hull 12 is approximately 137 m (450 feet).
, the diameter of the inner bulkhead 78 is approximately 61 m (200 feet);
The height of the hull 12 is approximately 15.3 meters (50 feet), and the columnar stabilizer 14 has a diameter of approximately 7.6 meters (25 feet) and a length of approximately 27.5 meters (90 feet).

Note that the center of gravity of the hull 12 is always at its lowest point because seawater is always at the bottom of the tank 84 and oil is always at the bottom of the tank 80. Therefore, the unit station 10 is extremely stable.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view of the unit station according to the present invention, FIG. 2 is a side view of the connection mechanism below the sea surface, and FIG. 3 is a partially cutaway top view of the unit station shown in FIG. 1.
Figure 4 is an enlarged sectional view taken along line 4-4 in Figure 3. Figure 5 is a diagram of the tank connection section that schematically shows the fluid filling operation to maintain a steady state of buoyancy, and Figure 6 is a diagram that diagrammatically shows the initial working state in which the unit station is towed to the work site. Figure 7 is a diagram illustrating an intermediate work state in which the unit station is submerged; Figure 8 is a diagram illustrating a state in which the digging rope mechanism is installed on the unit station; Figure 9 10 is a diagram showing a state in which oil is stored in a unit station to be sent to a tanker, and FIG. 10 is a diagram schematically showing a fluid control system.
11 is an enlarged sectional view taken along line 11-11 in FIG. 3, and FIG. 12 is an enlarged sectional view taken along line 12-12 in FIG. 10...Collection/storage unit/station,
12...Hull body, 14...Stabilizer, 16...Strut, 18...Platform, 22...Universal joint, 32...oil well, 72...recovery tank 76...bulkhead member, 80...first
Group tank 84...2nd group tank, 88, 92...Connector, 118...
...Manifold, 136,138...Flow control valve.

Claims (1)

[Scope of Claims] 1. In an oil extraction and storage method in offshore oil drilling using a semi-submersible method, a ship-shaped body having a plurality of liquid-tight tanks fixed to each other in juxtaposition is sunk, and one of the tanks is Air at substantially atmospheric pressure is introduced into the first group of tanks, and seawater as ballast is introduced into the second group of tanks to prevent the hull from sinking to a predetermined level. The buoyancy of the oil extraction/storage unit/station is determined to maintain its position, and the air and seawater in the first and second groups of tanks are injected at a rate such that the hull maintains the balance of the tight water position. On the contrary, the oil extraction and storage method is characterized in that oil is introduced into the first and second groups of tanks at the same time. 2. The oil extraction and storage method according to claim 1, characterized in that the volumes of air and seawater introduced into the tank are in a ratio of approximately 2:9. 3 While maintaining the hull at the predetermined tight water position, oil is simultaneously taken out from the first and second groups of tanks, and air is introduced into the first group of tanks in place of the taken out oil, and air is introduced into the second group of tanks. The oil extraction and storage method according to claim 1, characterized in that seawater is introduced into the group's tank. 4. In an oil extraction/storage unit/station in offshore oil drilling using a semi-submersible method, a submersible integral ship-form body having upper and lower surfaces for fluid storage;
a plurality of liquid-tight tanks fixedly secured within the hull; a first group of tanks for containing air and oil; and a second group of tanks for containing water and oil.
each tank has a connector for fluid inflow/outflow;
introducing air into the first group of tanks through the connector and introducing water as ballast into the second group of tanks to provide buoyancy to the hull to maintain a predetermined tight water position; a fluid control device;
the fluid control device for introducing oil into the first and second groups of tanks and simultaneously discharging air and water from each tank while maintaining the hull in the predetermined tight water position; and a plurality of stabilizers arranged in an upright manner at the outer peripheral end of the hull, each of which is attached to the hull by a connecting member, and thereby capable of linking movement relative to the hull. oil extraction and storage unit/station.