US2594105A

US2594105A - System for gathering and loading oil from underwater oil wells

Info

Publication number: US2594105A
Application number: US27084A
Authority: US
Inventors: Richard G Watts
Original assignee: Socony Vacuum Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1948-05-14
Filing date: 1948-05-14
Publication date: 1952-04-22
Anticipated expiration: 1969-04-22

Description

April 22, 1952 R. G. WATTS 2,594,105 SYSTEM FOR GATHERING AND LOADING OIL FROM UNDERWATER OIL WELLS Filed May 14, 1948 STORAGE RECEIWNG ZHNK I ll

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INVEN TOR. g g Bid 1 A E? ML Q w 3 2 AGEZVT Patented Apr. 22, 1952 SYSTEM FOR GATHERING AND LOADING OIL FROM UNDERWATER OIL WELLS Richard G. Watts, Dallas, Tex., assignor, by mesne assignments, to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of' New York Application May 14, 1948, Serial No. 27,084

8 Claims.

This invention relates to the production of oil from underwater oil wells and relates more particularly to the gathering and the loading for transportation of oil produced from underwater oil wells.

In the operation of oil wells located on dry land, the oil produced from the well may be passed directly from the Christmas tree, 1. e., the valve and pipe arrangement at the top of the bore hole, to storage tanks to await transportation via pipe line or tank cars to an oil refinery. By providing suflicient storage capacity to compensate for fluctuations in the rate at which the oil may be transported in the pipe lines or loaded on the tank cars, a continuous rate of production of oil from the well may be maintained which is highly desirable from the standpoints of insuring the maximum total recovery of oil from the producing formation, maximum utility of pumps, valves, lines, etc., and stability of operation. The same considerations with respect to maintaining uniform rates of production apply to underwater, or off shore, oil wells and uniform rates of production may be maintained from these wells as from wells located on dry land by providing sufiicient storage capacity to compensate for fluctuations in the rate at which the oil may be transported to the refinery.

However, in the operation of underwater oil wells, particular problems of maintaining uniform rates of production arise from the peculiar nature of the location of the wells. Underwater pipe lines leading from the well to the shore are diflicult and expensive to lay and other means of transportation are economically more desirable. Transportation of oil from the Well to the shore by means of barges or tankers is economically favorable and to be preferred to pipe lines. However, where barges are employed, unfavorable weather conditions of high waves and winds frequently make it impossible to load the barges and therefore make it necessary to discontinue production or to provide sufficient storage capacity to handle continuous production for whatever may be the maximum period of adverse weather conditions. On the other hand, the provision of suificient storage capacity by means of conventional tanks positioned above the water on pilings is extremely costly, leaving little to choose, from an economic standpoint, between transportation by barges and transportation by pipe lines.

It is an object of this method to provide an economical method for transporting oil from underwater oil wells. It is another object of this invention to provide a method whereby oil from underwater oil wells may be economically transported by barges. It is another object of this invention to provide a method for gathering and loading oil from underwater oil wells. It is another object of this invention to provide an economical system for maintaining continuous production from underwater oil wells. It is another object of this invention to provide an apparatus for gathering and loading oil from underwater oil wells. These and other objects of the invention will become apparent from the following description thereof.

In accordance with the invention, oil from an underwater oil well is gathered from the well and stored in a storage tank positioned sufficiently below the surface of the water to be unaffected by wind and surface waves, said tank being maintained liquid full at all times, and drawing off oil from the storage tank to a transport barge as desired. By maintaining the storage tank liquid full at all times with either oil, water, or oil and water, and providing sufficient ballast, if necessary, the buoyancy effect of the surrounding water is overcome and the storage tank is thereby maintained in its underwater position. The storage tank is provided with an oil inlet line, an oil outlet line supported at a mooring dolphin, and provision is made to permit water to enter or leave the storage tank.

By providing a storage tank or a plurality of storage tanks positioned below the surface of the water, sufficient storage capacity may be obtained to handle production from a well for long periods of adverse weather conditions, when weather conditions and, by proper anchoring, the

storage tank will not be susceptible to movement or drifting by underwater currents.

The storage tank may be of any suitable type, such as a cylindrical tank. If desired, an oil transport barge, sunk to an underwater position, may be utilized as the storage tank. The tank may be positioned at the bottom of the body of water, where the bottom is hard, or may be permitted to sink into the bottom, where the bottom 3 is soft. If desired, the tank may be positioned intermediate to the bottom and the surface of the water, although in this case it will be necessary to provide anchoring means to provent the tank from rising to the surface where its overall specific gravity is less than that of the surrounding water, as where it is filled with oil, or hanging means, such as pilings sunk into the bottom, to prevent the tank from sinking to the bottom where its over-all specific gravity is greater than the surrounding water, as where it is filled with water. Ballast may be employed to maintain the over-all specific gravit of the tank above the specific gravity of the water whereby the tank will maintain its position at the bottom or sunk into the bottom, or prevented from rising if positioned intermediate to the bottom and the surface. Air tanks or the like may be provided to maintain the over-all specific gravity of the storage tank below that of the surrounding water whereby the tank will be prevented from sinking where it is positioned intermediate to the bottom and the surface.

In operation, oil from the well is passed into the storage tank through the oil inlet line, at a pressure in excess of the hydrostatic pressure of the surrounding water, and the water contained in the tank displaced. If the pressure of the well is not in excess of the hydrostatic pressure, a pump may be employed to provide the necessary pressure. The displaced water leaves the storage tank through a water line located at the bottom of the tank and this line is provided with a valve actuated by change in specific gravity of the liquid passing through to close the line and prevent loss of oil when all the water has been displaced. Preferably, a mechanically operated valve is also provided on the water outlet line to insure that no loss of oil is encountered in the event of failure of the specific gravity operated valve. The oil inlet line is provided with a check valve to prevent any flow of water from the storage tank to the oil well. The tank is provided with a pressure operated valve to open if excessive pressures develop within the tank, thereby preventing damage to the tank.

7 Oil is removed from the tank from an oil outlet line, supported by a mooring dolphin, to a transport barge. Since water has a higher specific gravity than oil and the oil in the tank is at the hydrostatic pressure of the surrounding water, the oil may flow to the barge without the assistance of pumps, where the tank is at a sufiicient depth. However, the use of a pump is desirable, in any case, in order to lessen the time required to load the transport barge; Water enters the tank, thereby displacing the oil being loaded on the barge, and the water may enter through the same line through which it leaves when displaced by the oil, or it may enter through a separate line. The oil outlet line is provided with a valve, actuated by change in the specific gravity of the liquid passing through, to close the line and prevent How of Water to the transport barge when all the oil has been removed from the tank. Where a separate water inlet line is employed, valve means should be provided to prevent loss of oil from the tank through this line.

Figure 1 is a plan view, schematically illustrating one embodiment of the invention. Figure 2 is a plan view, in section, schematically illustrating a valve which will permit passage of water but which will close when oil flows to it.

Figure 3 is a plan view, in section, schematically illustrating a valve which will permit passage of oil but which will close when water flows to it.

Referring now to Figure 1, producing platform i0 is supported on a plurality of pilesll sunk into the bottom 12. Casing I l from oil well 15. extends through the water I6 to platform IE] and is capped with the usual arrangement of valves, pipes, and gauges commonly referred to as a Christmas tree and represented here for purposes of simplification as valve I'I. Line [9 leads from valve [1 to storage receiving tank 20 positioned at the bottom of the body of water and carries oil from the well to the tank. Line I9 is provided with valve 21 which may be any suitable type of check valve permitting flow of 'fiuid into the tank but preventing fiow of fiuid from the tank back through line H) to the well. Water in the tank 29 is displaced by the incoming oil and flows from the tank through line 22 to the surrounding water. Line 22 is provided with valve 24 which permits passage of water but closes when oil begins to fiow through the line.

Details of valve 25 are schematically illustrated in Figure 2. Channel 25 leads to the tank and channel 26 leads to line 22. ..Direction of flow from the tank is indicated by the arrows. Ball 2'! has a specific gravity between the specific gravity of oil and water, for example, a specific gravity of about 0.90 and such specific gravity may be obtained by hollowing out a suitable volume of the interior of the ball, the hole for hollowing being preferably plugged thereafter to provide a ball having a smooth surface. Water flows through the channel 25 and through perforated cone-shaped disc 29 to channel 26. While water is flowing through the valve, the ball, being lighter than the water, will float and maintain its position in the center of the disc 29. However, when oil enters the valve, the ball, being heavier than the oil, will sink to its position as shown by dotted lines in throat 30 thereby stopping the flow of oil.

Line 22 is also provided with valve 3i in order to close line 22 in the event of failure of valve 24 or to prevent water from entering the tank should it be desired to fill the tank with air to raise it to the surface or otherwise. Valve 3! is operated by chain 32 connected to sprocket 34 mounted on the platform 10.

Tank 2%} is provided with a liquid level gauge 35 which may be of the electric resistance'type or other suitable type to indicate the level of the oil or water in the tank. Connection 36 leads to indicator 31 mounted on platform in whereby the liquid level may be read from the platform. Tank 20 is also provided with a pressure operated valve 39 which opens when the pressure in the tank exceeds a predetermined value in order to prevent damage to the tank.

Anchor chains 40 and 4| hold the tank between

piles

42 and 44. The

pilings

42 and 44 may also serve the purpose of guiding the tank to the surface where the tank is to be floated for repairs, removal to a new location, etc. Two

piles have been shown. However, it may be desirable to employ a larger number of piles. The piles may be driven such that their tops extend above the surface of the water as shown, or their tops may be below the surface of the water.

Oil is removed from tank 28 through line 45 provided with valve 46. As oil is removed from the tank, water enters through line 22, valve 24 permitting fiow of water into the tank. Valve 46 is of the specific gravity operated type and will close to prevent flow of water into line 45. Details of valve 46 are schematically illustrated in Figure 3. Channel 4'! leads from the tank and'channel 48 leads to line 45. Direction of flow from the tank is indicated by the arrows. Ball 49 is similar to ball 21 in valve 24 and will remain in the center of perforated coneshaped disc 50 while oil flows through the valve. When water fills the valve, ball 49 will float to the position indicated by dotted lines in throat 5| stopping the fiow of water.

Line 45 leads to the surface to mooring dolphin 52 supported on a pluraity of piles 54. Preferably, mooring dolphin 52 is located at a sufficient distance from producing platform I!) to reduce fire hazards by preventing spread of any fire from the mooring dolphin to the platform. Also, the mooring dolphin is located a sufficient distance from the producing platform and the

piles

42 and 44 to permit loading barge 55 to be moored at any position in a circle around the mooring dolphin. Pump 56 assists in removing oil from the tank and may be powered by a diesel, gas, or gasoline engine or by an electric motor. The oil from pump 56 goes through flexible loading line 51 from swivel 58 to barge 55. Buoy 59 supports line 51 at the surface of the water and drift of the buoy is prevented by anchor line 60 held taut by means of weight 6|. Valve 62, mechanically operated by chain 54 from sprocket 65, serves the purpose of closing line 45 when barge 55 has been loaded and disconnected from line 51 in order to prevent any loss of oil from line 51 by reason of hydrostatic pressure on the tank 20.

Having thus described my invention it will be understood that such description has been given by way of illustration and example only and not by way of limitation, reference for the latter purpose being had to the appended claims.

I claim:

1. The system for gathering and loading oil from an underwater oil well which comprises in combination a well head for said well, a storage tank positioned underwater at a sufficient depth to be unaffected by the moving forces of surface conditions of wind and waves, means for trans ferring oil from said well head to said storage tank, means associated with said last named means for preventing flow of fluid from said storage tank to said well head, means for permitting water surrounding said storage tank to enter and leave said storage tank, means associated with said last named means for permitting said water to enter and leave said storage tank but preventing flow of oil therethrough from said storage tank, a mooring dolphin, means supported by said mooring dolphin for transferring oil from said storage tank to a loading vessel, and means associated with said last named means for permitting flow of oil from said storage tank to a loading vessel but preventing fiow of water therethrough from said storage tank to a loading vessel.

2. The system for gathering and loading oil from an underwater oil well which comprises in combination a well head for said well, a storage tank positioned underwater at a suflicient depth to be unaffected by the moving forces of surface conditions of wind and waves, means for transferring oil from said well head to said storage tank, means associated with said last named means for preventing flow of fluid from said storage tank to said well head, means for permitting water surrounding said storage tank to enter and leave said storage tank, means associated with said last named means for permitting said water to enter and leave said storage tank but preventing flow of oil therethrough from said storage tank, a mooring dolphin, means supported by said mooring dolphin for transferring oil from said storage tank to a loading vessel, means associated with said means supported by said mooring dolphin for permitting .fiow of oil from said storage tank to a loading vessel but preventing flow of water therethrough from said storage tank to a loading vessel, and valve means associated with said means supported by said mooring dolphin for starting and stopping flow of fluid therethrough.

3. The system for gathering and loading oil from an underwater oil well which comprises in combination a well head for said well, a storage tank positioned underwater at a sufficient depth to be unaffected by the moving forces of surface conditions of wind and waves, means for transferring oil from said well head to said storage tank, means associated with said last named means for preventing fiow of fluid from said storage tank to said well head, means for permitting water surrounding said storage tank to enter and leave said storage tank, means associated with said last named means for permitting said water to enter and leave said storage tank but preventing flow of oil therethrough from said storage tank, a mooring dolphin, means for transferring oil from said storage tank to said mooring dolphin, means associated with said last named means for permitting flow of oil from said storage tank to said mooring dolphin but preventing flow of Water therethrough from said storage tank to said mooring dolphin, and means for transferring oil from said mooring dolphin to a loading vessel.

4. The system for gathering and loading oil from an underwater oil well which comprises in combination a well head for said oil well, a storage tank positioned underwater at a sufficient depth to be unaffected by the moving forces of surface conditions of wind and waves, an oil transfer line connecting said Well head and said storage tank, a check valve in said oil transfer line to prevent flow of fluid from said storage tank to said well head, a line to said storage tank open to the surrounding water, a valve in said line permitting flow of Water through said line to and. from said storage tank but preventing flow of oil through said line from said storage tank, a mooring dolphin, an oil transfer line connected to said storage tank and leading to said mooring dolphin, a valve in said last named oil transfer line permitting flow of oil through said line from said storage tank to said mooring dolphin but preventing fiow of water through said line from said storage tank to said mooring dolphin, and a loading line connected at said mooring dolphin to said last named oil transfer line.

5. The system for gathering and loading oil from an underwater oil well which comprises in combination a well head for said oil well, a storage tank positioned underwater at a sufficient depth to be unaffected by the moving forces of surface conditions of wind and waves, anchoring means associated with said storage tank to prevent drifting of said storage tank by underwater currents, an oil transfer line connecting said well head and said storage tank, a check valve in said oil transfer line to prevent flow of fluid from said storage tank to said well head, a line to said storage tank open to the surrounding water, a valve in said line permitting flow of Water through said line to and from said storage tank but preventing flow of oil through said line from said storage tank, a mooring dolphin, an oil transfer line connected to said storage tank and leading to said mooring dolphin, a valve in said last named oil transfer line permitting flow of oil through said line from said storage tank to said mooring dolphin but preventing fiow of water through said line from said storage tank to said mooring dolphin, and a loading line connected at said mooring dolphin to said last named oil transfer line.

6. The system for gathering and loading oil from an underwater oil well which comprises in combination a producing platform set on piles, a well head for said oil well on said producing platform, a storage tank positioned underwater adjacent to said platform and at a sufficient depth to be unaffected by the moving forces of surface conditions of Wind and Waves, means for transferring oil from said well head to said storage tank, means associated with said last named means for preventing flow of fluid from said storage tank to said well head, means for permitting water surrounding said storage tank to enter and leave said storage tank, means associated With said last named means for permitting flow of water to and from said storage tank but preventing flow of oil from said storage tank, a mooring dolphin, means for transferring oil from said storage tank to said mooring dolphin, means associated with said last named means for permitting flow of oil from said storage tank to said mooring dolphin but preventing flow of Water from said storage tank to said mooring dolphin, and means for transferring oil from said mooring dolphin to a loading vessel.

7. The system for gathering and loading oil from an underwater oil well which comprises in combination a producing platform set on piles, a Well head for said oil well on said producing platform, a storage tank positioned underwater adjacent to said platform and at a sufficient depth to be unaffected by the moving forces of surface conditions of wind and waves, an oil transfer line connecting said well head and said storage tank, a check valve in said oil transfer line to prevent flow of fluid from said storage tank to said well head, a line to said storage tank open to the surrounding water, a valve in said line permitting flow of Water through said line to and from said storage tank but preventing flow of oil through said line from said storage tank, a mooring dolphin, an oil transfer line connected to said storage tank and leading to said mooring dolphin, a valve in said last named oil transfer line permitting flow of oil through said line from said storage tank to said mooring dolphin but preventing flow of water through said line from said storage tank to said mooring dolphin, and a loading line connected at saidmooring dolphin to said last named oil transfer line.

8. The system for gathering and loading oil from an underwater oil well which comprises in combination a producing platform 'set on piles, a Well head for said oil well on said producing platform, a storage tank positioned underwater adjacent to said platform and at a suflicient depth to be unaffected by the moving forces of surface conditions of wind and waves, anchoring means associated with said storage tank to prevent drifting of said storage tank by underwater currents, an oil transfer line connecting said well head and said storage tank, a check valve in said oil transfer line to prevent flow of fluid from said storage tank to said well head, a line to said storage tank open to the surrounding water, a valve in said line permitting flow of water through said line to and from said storage tank but preventing flow of oil through said line from said storage tank, a mooring dolphin, an oil transfer line connected to said storage tank and leading to said mooring dolphin, a, valve in said last named oil transfer line permitting flow of oil through said line from said storage tank to said mooring dolphin but preventing flow of Water through said line from said storage tank to said mooring dolphin, and a, loading line connected at said mooring dolphin to said last named oil transfer line.

RICHARD G. WATTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS