MXPA99006313A - Hull construction - Google Patents

Abstract

There is referred to a hull construction for a single hull vessel (10), especially designed for drilling and production operations in largely stationary positions. The hull construction is characterised by a combination of individually known features:a) one or more open wells (26, 28, 30) extending through the hull for the inward and outward flow of water from below, b) one or more walls (36) of the well/the wells (26, 28, 30) comprise a number of water flow delaying elements in the form of:one or more bulges/lips (34), projecting outwards from the well wall (42), which in a region constrict the water-inflow area of the well (26, 28, 30), and/or a number of water-inflow delaying hollow spaces (42) which are flow connected with the well hollow space via perforations (44), and, c) that the outside of the hull comprises a longitudinal bulge/lip (34) projecting horizontally outwards preferably arranged below the water line (20) of the hull (10).

Description

HELMET CONSTRUCTION DESCRIPTION OF THE INVENTION The present invention relates to a construction of a hull for a vessel, especially a drilling vessel and / or production for hydrocarbons, as indicated in the introduction to the following claim 1. The invention also relates to the application of a construction of helmet according to the invention. The invention is especially related to the design of hulls for single hull boats which are provided to carry out operations at sea, and especially boats which are used for drilling oil wells and for the intervention and maintenance of this type of well. With the invention, the objective is to provide a hull shape for a vessel which returns to the vessel especially suitable for performing this type of well operations in deeper water and in the sea, so that the vessel can operate even in conditions of difficult weather which are generated by waves, ocean currents and winds. The hull design according to the invention will also be suitable for boats which are used for other common purposes where it is important to control the movements of the ship in waves, as an example in the production of boats for hydrocarbons and boats which carry out seismic investigations of formations below the seabed. Drilling in search of oil and gas is carried out either in floating drilling vessels or devices attached to the bottom. The known floating types of vessels may be either semi-submersible drilling rigs, which are referred to as "semisubmarines" or may comprise drilling rigs for this type of operation. Semi-submersible drilling rigs have had an extended application in regions of difficult climate at sea because this type of sounding has a particularly favorable response to movement with respect to waves. By favorable movements of the boat it is meant that the oscillations, that is to say the amplitudes, during the vertical movement, the rolling and the pitch are relatively small in big waves. It is very advantageous to obtain movements of small amplitude due to the fact that smaller demands can be made on the drilling equipment on board the probes. At the same time, the response cycle is prolonged, that is, usually 15-16 seconds or longer. For a ship which moves up and down in the waves, its response cycle is defined by the time elapsed from a maximum and the return to the same maximum. The long response cycles are favorable for the equipment which is supported on board the drilling vessel because the accelerations in the movements in this way become moderate, in some way which establishes less demands on the equipment on board. the sounding With respect to the response cycles, reference is made to the annex diagram where the characteristic movements of different boat constructions are compared during the different wave cycles that are presented. The favorable movements for the semi-submersible probes are due to the fact that these types of floating drilling devices consist of a series of vertical columns which break the waterline, and at the same time that the columns are structurally joined together by the cover of the device and by horizontal pontoons below the surface of the water. In this way, a waterline area of the semi-submersible platforms is obtained, which becomes less relative to the total flotation volume. Since the largest portion of wave forces arises in the waterline area, and decreases downward with depth, wave forces are reduced in these types of devices. In addition to the horizontal pontoons that have a favorable effect on the movements of vertical movement of the polling machine (the semisubmarine) because they function mainly as a brake in the vertical direction when the surrounding mass of water breaks and therefore provides a mass additional theoretical to the polling machine. further, it will be noted that by the natural waterline of the hull, it is meant a natural waterline when the hull has finally completed its devices, machinery, etc., for a vessel such as a drill ship or the like. For all types of floating drilling vessels, vertical oscillation movements are especially critical. This is due to the fact that the boats, during the operations, have a tube piercing bar which hangs in the drilling sounding of the boat and extends downwards, through the well. This bar is rigid, and in order to ensure that the movements of the bar to drill down through the well are not contracted by the movements of the boat, the boat is also provided with special devices which can compensate the movements of the boat. ship. These provisions, however, have limitations with respect to movements, accelerations and maximum oscillations, and this involves wishing to minimize the stresses on this equipment by accurately controlling the design of the hull of the vessel. In spite of their good movement characteristics, the semi-submersible probes have clear disadvantages with respect to the realization of effective drilling operations in terms of costs. A disadvantage is, for example, that the hull becomes very expensive to build since it is constituted by columns, pontoons, struts and decks. In addition, such semi-submersible probes are especially sensitive to displacements of the center of gravity, for example, when moving load on the cover. The biggest disadvantage, however, is that the total payload which can be placed on board is limited when taking into account the stability of the polling machine. This implies that a semi-submersible probe depends on the continuous supplies of consumable material during the drilling operation. This is normally carried out when supplying boats which are specially manufactured for this purpose. However, this is very expensive to carry out, because as a rule, a vessel is required to be available for the derrick at all times. In addition, when drilling operations are carried out at sea far from the coast, and possibly at a substantial distance from the nearest supply base, this involves a significant increase in costs. In addition, deep and long wells require additional supplies of supplied items which contribute to additional costs. If the supply lines are particularly long there may be a need for an additional supply ship in continuous operation. The initial semi-submersible polling machines had a payload capacity of approximately 2,000 tons, while today's modern semi-submersible polling machines have a payload capacity of more than 4,000 tons. A semisubmersible surveyor is usually anchored during offshore drilling operations, and 8-10 anchors are often placed at the same time. In addition to drilling boats with semisubmersible probes, they are also used as floating drilling vessels in the sea. These have the advantage that they can take considerably larger loads on board. A drilling ship can often carry the entire payload on board before it is placed in the sea in order to drill the well. This makes the drilling ship almost independent of supply vessel assistance. Although a semi-submersible sounding depends on tugs when it is to be transferred from one well to another, a boat can also travel with its own propulsion machinery. In those regions where you are far away from the nearest supply base, such as, for example, in the Far West, where oil is sought at sea several days a day from the supply base, such drilling boats have found wide application.

However, drilling ships have obvious limitations in terms of their field of application. Known drilling vessels are produced as conventional single-hulled vessels. This implies that they are very sensitive to larger waves since they have a less favorable motion response compared to the usual semi-submersible polling machines. These poor dynamic oceanic features for drilling have meant that drilling ships, despite their excellent carrying capacity, can not be used in more inhospitable regions such as the North Sea and the Atlantic Ocean. Drilling boats, however, have a high prevalence and application in more hospitable regions, where the waves are relatively small, for example in positions at sea outside of Brazil, Indonesia and the like. A drilling ship will have a relatively large waterline area compared to semi-submersible probes and is therefore more exposed to the forces of the probes compared to the probes. Although an anchored probe is almost not influenced by the direction of the environmental forces that occur in it, a drilling ship depends on being able to rotate with the weather at all times so that it is capable of reducing the forces to the same. that the ship is exposed. This implies that the drill ship must be equipped with a data-driven automatic positioning system which guarantees the relative position with respect to the well and the direction of the wind, waves and currents. The most important drawback with known drilling vessels is that they are sensitive to vertical oscillation movements which are generated by waves, both in terms of amplitude and cycle. Known drilling vessels have a length of 160-180 m and a typical width of 22-25 m. All of these types of boats have large parallel ship sides and have a normal vertical movement cycle of 7-8 seconds. This places moderate demands on the equipment to the extent that the oscillations of vertical movement are moderate. A normal maximum vertical movement for a drilling vessel is 7 m (ie 2 x amplitude), and this can theoretically be handled by known compensating systems. However, this is completely insufficient for regions with more difficult climates, where this type of boat can easily acquire vertical oscillation movements of 8-10 m depending on the height of the waves and the weather conditions. Theoretically, the simplest way to solve this problem would be to broaden the extreme values of the compensating system of the drilling rig, but with such short cycles this will mean great accelerations of the equipment with consequent forces and tensions which can lead to fractures and fatigue. Another theoretical way to solve this problem may be to increase the size of the boat. Possibly in combination with an increase in the capacity of the compensating system. For example, a ship that has a length of 300 m, a width of 40 m and a height of 25 m, can move with small amplitudes and have long movement cycles, in addition, it can have a significant load capacity. Therefore, such a vessel will theoretically be able to combine the movement characteristics of the semi-submersible surveyor and the loading capacity of the drill ship. However, this is a very expensive and impractical solution because the investment becomes very high, plus the need for motor power which must be installed to maintain the position on the well of a field which will be very large and Correspondingly, fuel costs will be high. In addition, a ship of this type would be very difficult to transfer and in practice it would be problematic to place supply bases where there is the possibility of taking provisions on board for the next cycle of operation. In order to be able to carry out drilling operations reliably and effectively, it is a particular need that the ship's own cycles of vertical movements are increased, and at the same time the vertical movement becomes as low as possible. The movements of the ship in roll and in certain degree of pitch also mean something, but they are less critical. It is known that the shape of the single-hull vessel will have an influence on the vertical movement response of the ship, both with respect to the cycle and the amplitude. Therefore, Japanese Patent Publication 57058584 discloses a hull design which will be capable of reducing a pitching movement of a single hull vessel. The shape of the hull that is described indicates a projection or longitudinal lip of the ship's hull below the waterline. This can also increase the ship's own vertical movement cycle. Other patent specifications have variations of the lip below the waterline, such as the patent NO number 4,829, the patent of the United States No. 2,327,660 and the patent of the United States number 4,372,240. Pond tests conducted by patent applicants have confirmed that the longitudinal lip below the waterline of the vessel can provide a positive effect on the movement pattern of the vessel for a large part of the wave spectrum, both with respect to to the cycle as to the amplitude. However, pond tests have also shown that for a small portion of the wave spectrum vertical movement will be able to be strongly reinforced if only the lip is present. A resonance arises around the natural vertical movement cycle of the boat itself, so that the amplitude (half of the maximum oscillation) in this region of the cycle will actually become larger with lips than without them. For a drilling ship this is a safety concern that is totally unacceptable. In practice this means that in many cases, such lips alone are not suitable for use in a drilling ship. In U.S. Patent 3,386,404, different helmet designs with lips are indicated, in combination with water which flows in and out of the partially enclosed spaces in the ship's hull. The partially enclosed spaces are placed on external sides of the ship. The patent publication highlights the theoretical foundations that water flowing in this way will be able to have a positive effect on the movements of a ship in difficult seas. The proposed practical design of a single-hulled ship (see Figure 6 in the patent publication) can possibly be exploited on a passenger ship or a commercial ship, however, it is completely unacceptable for use on a drilling ship. This is due to the fact that the proposed double spaces will occupy much of the vessel's utility volume. This can be compensated to some extent by making the boat larger, but this is a costly solution. However, the biggest problem is that modern ships for use in drilling and for the storage of crude oil will require a sealed double hull. Double helmets are a protection against contamination or collisions and groundings. This is not possible with the proposed solution without establishing a sealed third inner hull. However, this increases the weight of the steel and the costs of the ship additionally, something which ultimately is harmful to the payload of the ship. It has also been found that such spaces have other unfortunate side effects. Even if the inward / outward flow of water dampens vertical movements, the waves provide very large impulse and pull stresses on the hull. The corresponding conditions will be applied to the pontoon, which is known from GB-2,008,515. The divided lateral surfaces involve large horizontally directed pulling forces as well as lateral movements. The corresponding to the tank known as EKOFISK in the North Sea and which has such a construction is applied. Such external hollow spaces on the side of the hull in which water can flow in and out through perforations, affects in an unfavorable way the movement pattern in the waves of a floating construction, and is an impediment which is currently directly confirmed by Figure 4 of the patent publication of GB 2,257,664. Figure 4 of the patent clearly shows the effect of the perforations externally on the pontoon parts of the semi-submersible construction. The three curves represent the following: curve 30: pontoon sealed with water curve 31: perforations at 10% curve 32: perforations at 20% curve 33: perforations at 30% The figure shows that for most of the wave cycle interval that occurs frequently is 7-13 seconds, which will also apply to the North Sea, so that the perforations in the outer hull of the pontenes indicate a worsening of the response of the platform compared with a non-perforated pontoon, with with respect to the increasing wave cycles. In addition, this response increases the percentage of perforations, 30% of perforations provide a greater response compared to 10% of perforations. According to Fig. 4, the improvements (relative to the non-perforated curve 30) with the perforations shown first when the cycle exceeds approximately 16 seconds and then in the first number of higher perforations provides the best and lowest answer. But despite the fact that the perforations of the three curves are over 1.0 in response, that is to say that the entire wave cycle - interval for 14 seconds, the platform will have upward movement greater than the height of the wave, and with a factor of up to 1.15-1.35.

This means that it is unfavorable to place hollow spaces which are accessible through holes in the outer parts of the hull which are affected by the waves, and also provides strong horizontal pulling forces to the boat. U.S. Patent No. 3,386,404 also describes possible solutions for the use of the principle in semisubmarines (see Figure 7) and double hull vessels (see Figure 8). For semisubmarine sounding, the solution has little attraction due to the increased weight of the steel in a boat already sensitive to weight. Double-hull vessels are ill-suited to operate in difficult seas because it has been found that larger waves can lift the deck between the hulls, something which can produce large stresses on the entire hull construction. The proposed solution to dampen the upward movements in a double hull vessel therefore worsen the situation as the probes increase even more easily on the underside of the hull. The use of open ship walls on the ship (Eng. Moonpool) is well known, and is used, for example, in the transport of live fish and in a series of offshore vessels which are used to lift tools and equipment and then they go up and down from the seabed. The equipment, such as remotely controlled devices, maintenance implements, etc., can easily be lifted from the deck in this way, through the well and down to the sea floor. A typically large well for an inspection vessel for the North Sea has a horizontal hull opening of 3 x 5 m and up to 7 x 7 m. The size of 7 x 7 m is also a typical size for drilling ships built so far. Here it should be mentioned that the solution which is known from the patent publication DE 2526609. Here, the aim of the well however is not to be able to influence the movements of the ship at sea. Instead of this, it is specified that the well has as a function to be possible underwater operations in a protected manner against the impact of the waves, for example, for immersion equipment at the bottom of the sea. In addition, it is known that the vertical movements of the construction in the waves is a direct function of its waterline area. The most recent drilling rigs, which have not been planned for hospital waters such as the Gulf of Mexico, and which are longer than 220 m in length, are planned with 10 x 10 m wellbore openings for conventional operations. well or drilling. This is done in such a way that one can be in a position to lower large well frames down to the bottom of the sea and other heavy and large equipment through the well of the ship. If the boat is going to be very deep and will be able to operate with two chains of tubes at the same time, the wells of the ship have been indicated up to 10 x 20 m. The drilling rigs planned for the Gulf of Mexico have a length of approximately 220 m and a width of approximately 40 m. The waterline area in these ships is approximately 8,000 m2. A maximum ship pit of 200 m2 therefore constitutes approximately 2.5% of the total waterline area. In smaller drilling vessels, for example a length of 180 m, the width of the waterline of 35 m and a waterline area of 6,000 m2, the well of the ship which, for operational reasons, has an area of Well waterline of 200 m2. It will constitute 3.5% of the entire waterline area. An object of the present invention is to provide a hull design for a single hull vessel, especially for drilling and production vessels, where the above-mentioned drawbacks related to the movements of the vessel are completely or partially eliminated. It has now been found that a modification in the design and dimensions of these wells can be of great importance in order to be able to control the vertical movements of a drilling ship. The helmet design according to the present invention is characterized by features which are evident from the characterizing portion of claim 1 below.

The especially preferred constructions of the invention are defined by the dependent claims that follow it directed to the helmet. According to the present invention, the hull construction is applied to ships, especially boats for subsequent drilling and / or oil and gas production or for seismic investigations, where the movements of the hull must be cushioned, especially the vertical movements, such as consequence of a difficult sea. The hull construction according to the invention will be further explained in the following description when considering the attached figures which: Figures 1 and 2 show a modality of a drill ship in perspective and the lateral section, respectively, designed on the basis of the helmet construction according to the invention. Figure 3 shows a plan view of the hull construction according to figures 1 and 2. Figure 4 shows a cross section of the hull construction taken along the line XX of figure 3. Figure 5 shows a perspective section of an especially preferred design of the inner well wall. Figure 6 shows cross sections of four transparent designs of a lip.

Figure 7 shows a graphic representation of the relationship (vertical movement) between the vertical movements and the height of the waves of different types of vessels (single hull according to the invention, and two semi-submersible platforms of different sizes) as a Wave cycle function. The curves are of the same type as those shown in GB-2257664 mentioned above. In the different figures similar parts of the helmet designs will be given the same reference numbers. By way of introduction, reference is made to Figures 1 and 2, which show a perspective view and a side section, respectively, of a drill ship which is constructed based on the hull construction 10 in accordance with the invention. Figures 1 and 2 show a drilling ship having a hull 10 with a lateral portion 12 in the center, the horizontal keel portion 14 and a prow portion 16, and a stern portion 18. The central part 12 of the hull has mainly perpendicular ship sides. Figures 1 and 2 show a drilling ship with a derrick 22 from which an oil / gas well is drilled or operated which advances down to the sea floor 23, or is operated by means of a bar to drill 24 or similar equipment. The bar 24 extends from the derrick 22 of the ship downwards, through a vertically extending well 28, open upwards and downwards in the ship. In addition to the well 28, the ship comprises two additional similar wells 26, 30 (aft and forward respectively). All these wells 26, 28, 30 are dimensioned as explained in the above, in order to provide the ship with the desired characteristics of movement in the sea. According to the invention, the hull of the ship comprises one or more wells 26, 28, 30 in order to alter the vertical movements of the ship in a favorable manner. The wells are open, that is to say, they extend continuously from the upper deck vertically through the whole of the ship and towards the exit to the sea in the horizontal keel. When the boat begins to move in the waves, the water level in each well begins to fluctuate up and down as a vertically movable water column (at rest) in relation to the waterline level. The water will remain an upward distance in the well in a stationary condition and is adjusted to a normal level which is called the waterline level, and such a level is more clearly evident with the reference number 20 in Figure 4. several alternatives for the number and placement of the wells. According to a solution, and which is shown in Figures 1 to 3, the ship is equipped with three wells with mainly rectangular flat sections, and which extend longitudinally along the longitudinal axis of the ship. It has been found that a distribution or disposition of the wells, that is, the well area, is favorable along the middle section of the ship. From the following, the preferable number of wells as well as their length and width dimensions are evident. Alternatively, the ship may comprise a single longitudinal well, and which may have the same waterline area (see below) as the three wells 26, 28 and 30 together. The beginning with which the wells are designed with uniform and mainly perpendicular well walls 36. It is desirable that the installations on the seabed be operated from a deck of the ship by means of these wells. As an alternative to wells with a rectangular or square cross section, they can also be designed with other shapes in cross section such as oval, circular or other more irregular shapes. The shape of the precise cross section will be subject to variation in accordance with the current hull construction, so that, for example, it is adapted to the needs of frame construction. The normal waterline of the ship is illustrated in Figures 2 and 4 by the reference number 20. The area (cross-sectional area) which covers the ship in a horizontal plane through the waterline of the ship, is defined as the waterline area of the ship. The length of the well or wells should be considered close along the length of the waterline area of the well or wells in relation to the waterline area of the ship. It has been found that in order to provide an important effect, the waterline area of the ship's well must exceed approximately 8% of the total waterline area of the ship. At the same time, the waterline area in the well should not exceed approximately 30% with a consideration of the vessel's capacity when taking into account the payload on board in relation to the total dimensions of the ship. A waterline area in the well of approximately 15% is considered to be very favorable. When the boat is exposed to rippling waters, it will flow into the wells from the bottom when the boat sinks down in a wave, while the water runs out of the well when the wave comes out by itself under the boat. According to a preferred construction, the portion of the well which is brought into contact with the mass of water that flows inwardly or outwardly, comprises a medium which functions as a delay or brake of the flow of water inwardly and outwardly. of the well, and which in this way can further improve the ship's inertial resistance against vertical movements. Figure 5 shows two such means, one involving the lower portion of the walls 36 of the well constituted by a flange projecting essentially horizontally outwards, facing outwardly of the well wall 36, with a recess 32 The upper portion is mainly planar, so that a lip 34 is formed. The lip 34 extends mainly around the entire periphery 36 of the interior wall of the well and thus forms an entry opening restricted to the well from the bottom. In the lower part of the well wall 36, the lip 34 apparently also is in connection with the forward well 30 of the ship in figure 3. Instead of the lip extending continuously around the periphery as shown in the figure , it can be divided into several lips that project outwards mutually separated / lips or eyelashes. These lips that project outward can also be placed at different height levels on wall 36 of the ship's well. According to the invention, the well of the ship comprises an additional means which can retard the flow in and out of water in the well. This can be done by placing one or more additional spaces along the walls of the well in which the water can flow in and out of them, which in turn retards the outward flow and in the water to the well, and which consequently contribute additionally to improve the movements of the boat. The space or spaces are formed, with reference to Figures 4 and 5, by installing in the well a wall plate 40 parallel to each of the well walls 36 so that a flowable space 42 is established inwardly and outwardly. of water. The space 42 is defined by the well wall 36, the plate 40, the upper side surface 32 for the well lip 34, and can be opened upwards. The plate 40 comprises several through holes or openings 44. In figures 4 and 5 a perforated plate 40 is shown, that is, with a series of regular through holes 44 which connect the space 42 with the well present outwards. The plate 40 may alternatively comprise a series of larger holes placed in a lower part against the lip, while the plate also does not include openings. By means of these devices, a portion of the water which enters the well will flow through the holes 44 in the plate 40 and into the interior space 42 present behind. In this way you get a delay in the flow of water inside and out, into the well. This causes the damping of the boat preventing vertical movements from increasing. In addition, the tests referred to are discussed in more detail in the following. The depth (the distance) from the perforated wall 40 (44) with respect to the sealed pit wall / supporting wall of the ship (36) existing behind in the tests with a full scale ship, which has a length of 180 m, The waterline width of 35 m and a total waterline area of approximately 6,000 m2 can be up to 1.6 m. However, a good damping effect can be obtained even when the depth below the wall 40 varies. The depth with respect to the supporting wall 36 present in the rear part can also be in the region of 1-5 m. As is evident from Figures 1 to 3, the hull has a horizontal keel portion with an approximately flat bottom. Along the outer side of the horizontal keel also extends a continuous or split upper lip 32, which may have the same construction as the lips 32 of the well. From the lower sides, the side of the ship extends by means of introducing mainly vertical rising parts and forms the substantially horizontal flange oriented inwardly of the flat recess 32 to form the lip 34 oriented outward mainly horizontally. The lip 34 extends mainly along the entire length of the horizontal keel from the bow and back to the aft portion of the ship. As mentioned in the foregoing, the existence of such a lip, during individual circumstances, produces negative effects on the upward movement characteristics of the ship, and therefore such a lip is not mandatory in accordance with the present invention. However, it may be preferred in combination with one or more wells of the ship since such combination may provide a synergistic effect. The outer lip of the hull according to the invention is tensioned from the bow portion of the boat and towards the aft rear part of the boat when it is tilted by the underside of the stern which constitutes the natural extension of the extension. Preferably, the lip is designed far below the bottom / horizontal keel portion of the ship as possible. Alternatively, the cross sections of the lip for both the lips of the horizontal keel and for the lips 34 of the well are shown in Figure 6. According to one of these (see Figure 6a), the flange portion extends in cross section as a mainly horizontal surface outwardly from the ship side portion 12 so that it then extends perpendicularly and further in an arched shape which then forms a smooth transition to the portion of the stem Horizontally flat bottom of the boat. According to another design shown in Figure 6b, the lip is provided, instead of the above, with a rounded shape, designed in cross section as a hemispherical shape. In Figure 6c an additional construction of the boat lip is shown. According to this construction, the lip is tilted downward and outward from the perpendicular side (from the well) of the ship so that it extends rectilinearly downward in order to tilt inwardly and downwardly and subsequently so as to extend over the inner part of the underlying horizontal keel portion of the hull. In this way a polygon is formed, which resembles a trapezoid.

According to a further construction, according to Figure 6d, the lip comprises a mainly horizontal and straight upper side, in order to extend rectilinearly perpendicularly and horizontally in an additional way inwards and passing over the horizontal keel portion . This construction is the one shown in Figures 1 to 5. As is evident, the otherwise sharp edges are rounded. According to the invention, the horizontal keel of the hull has a mainly flat bottom side so that the vertical movements of the ship in the sea are susceptible to being damped as much as possible.

OPERATION OF PRACTICAL TESTS, DETERMINATION OF THE DIMENSIONAL RELATIONSHIPS IN THE DESIGN OF THE HELMET ACCORDING TO THE INVENTION These pond tests have shown that a lip below the waterline only on the ship's hull has a positive effect on the ship's vertical motion response for larger portions of the wave spectrum, but in part it has a strong effect negative for a smaller portion of the wave spectrum where vertical movement is, on the contrary, reinforced, in order to compensate for this unexpected and negative effect of the lip, deep pond tests have been conducted under the direction of the applicants the patent where, based on what has been provided, tests have been carried out on a dynamically seen hull shape, with a widening below the waterline with respect to the effect of the different wells on the ship. Wells in the boat are varied in size, design and placement. The results show that when the waterline area of the wells increases, the negative resonance effect is gradually eliminated. In addition to an increase in the waterline area in the wells of the ship, it contributes to an additional damping of the vertical movement and an extension of the vertical movement cycle of the ship. During the pond tests, a hull model was tested based on a boat with a length of 180 m, a waterline width of 35 m and a total waterline area of approximately 6,000 m2, which was likewise included by a lip below the 2.5 m waterline that projects horizontally outward, which extends from the bow of the boat to almost completely the stern. The tests show, by way of example, that the given lip in combination with a ship's well area of 900 m2 or approximately 15% of the total waterline area of the ship, is capable of providing a maximum vertical full motion damping of the ship. 60% at a height H (s) of significant wave of 3 m, and approximately 45% at H (s) = 5 m. At the same time, the natural intrinsic cycle of the ascending movement of the ship increases by 2.5 seconds. At H (s) = 7 m, the effect of the lip and the large well area of the ship is reduced by approximately 20%. The sea condition in the boreal portion of the North Sea is H (s) < 5 m during 95% of the year. It is under these conditions that a drilling ship will operate and then the damping of the movements of the ship is substantial. In extreme conditions at H (s) > 5 m with maximum waves exceeding 9-10 m, it is expected that the drilling ship will be largely in non-operational mode waiting for better weather conditions. This is due to the fact that high seas are followed, as a rule, by strong winds, something that in some way causes the crane and elevators team not to be able to operate. For the response of the ship regarding the influence of waves, the distribution of the well area along the middle section of the ship has shown that it is favorable. At the same time, this performance makes it possible to retain the resistance from the front to the back of the ship's hull and that the region of the well can be placed inside the inner beam of the ship's hull. A total well area of 976.8 m2, that is, the width b = 13.2 and a length 1 = approximately 74 m, placed in the middle part shows itself satisfying the requirements for operability necessary for the ship in the northern part of the Sea of Norway and at the same time the requirements regarding the resistance of the ship, its high load capacity for variable loads, stability and ease of construction are maintained. A further improvement is obtained by dividing a single well into several smaller and mutually separated wells, for example, two units of b = 13.2 m and 1 = 23.2 plus one unit with b = 13.2 m and 1 = 27.2. It is probably due to the fact that the well area is divided over a much longer length along the front and rear axle of the ship. With 3 separate wells you get the ability to build beams and beam berths between the wells, which can improve the overall strength of the boat. In addition, you will have the ability to avoid the problem with the transformation of larger waves from the front to the back inside the well areas. For drilling technical operations it is favorable that the conditions of the ocean inside the well of a ship be as calm as possible. A surprising effect which arises by dividing the area into 3 wells has shown to be that the two outer wells, ie, the front and rear wells 26, 30 cancel to some extent the waves within the central well 28 where it is considered to be They will carry out the drilling operations.

By installing the lips inside the wells below the waterline you get an additional damping of the movements of the boat. The lips are placed adjacent to the bottom of the boat, in the same way as the outer lips of the hull, and then installed as an annular rounded shape on all sides of the well area. In the pond tests, the lips inside the well have a full scale width in a horizontal direction of approximately 1.6 m, something which, for example, provides an opening hole of 10 x 24 m in the central well. It is considered that a practical horizontal size of the lips inside the well is approximately 1-5 m. The central well will be favorable with respect to the well of a ship for drilling operations, while the main function of the remaining wells will be to improve the movement characteristics of the ship, especially with respect to the response cycle. By installing a substantially vertical wall 40 over the lips within the wells, which has several openings or openings 44, a delay in the inward and outward flow of water into the well, and especially the flow of water inwardly, is obtained. and outwardly to the space 42 below the wall 40 (when each of the walls is "coated" such that the wall 40 and the space 42 in this manner form an annular hollow space which surrounds the well opening) .

This involves further improving the damping of the boat when approaching a vertical movement. In the tests a perforated / uniform holes wall was used, which has circular perforations which constitute approximately 25% of the area of the wall. The tests show that a desired damping effect can be obtained with different constructions of the wall, where it is estimated that the area of the openings / holes 44 of the wall should be about 10-30% of the combined area of the wall 40. In the tests, the depth of the perforated wall with respect to the supporting wall of the sealed ship present in the rear corresponds to a full-scale ship of approximately 1.6 m, that is, the wall 40 is anchored approximately further outwards on the surface 32 upper lip 34. A damping effect can be obtained even if the depth behind this wall is varied. A practical depth for the support wall present in the back, is considered to be in the range between 1 and 5 meters. The combined test results provide very favorable movements for the ship's vertical motion response, especially in the most important oceanic conditions, H (s) < 5m. , for drilling operations.

H (s) of the Wave T (p) of the Wave H (max) of the O Vertical Oscillation Vertical Maximum Oscillation Reduction 3 m 9 sec 5.8 m 0.95 m 60% 5 m 11 sec 9.6 m 3.2 m 45% 7 m 12.5 sec 13.5 m 6.4 m 20% where H (s) = significant wave height T (p) = wave cycle in seconds H (max) = maximum wave height According to the invention, the ship has on each side of the hull an expansion in a horizontal direction, in a measurement of up to 5.5 meters. It has been found that the expansions / lips on each side of the helmet in the range of 1.5-5 meters have a good cushioning effect on the vertical movements for the helmet. For example, the largest lateral middle parts of a width of 20 including the expansion / lip can be up to 60 meters, while the width of the side 20 in the middle part of the helmet above the expansion can be up to approximately 50 meters It is preferred that the side 20 on the side parts of the helmet have a width which constitutes 20-35% of the total length of the helmet. That is to say, a helmet which has a length of 180 meters can have lateral widths in the middle part of up to 63 meters. For such helmet, it is preferred that the lips / expansion on each side be at least 5 meters. According to a construction, the proportion is 22%, that is, for a container that has a total length of 160 meters, the width in the middle part is 35 meters. According to another preferred construction, the widths in the middle part, for a helmet that has a length of 180 meters, is approximately 40 meters, that is, 25% of the length, and the width of the helmet in the middle part more Large that includes the expansion is approximately 50 meters. For example, a helmet can have a width Bl of 40 meters including the lip on each side (i.e., each lip has its horizontal dimension / width greater than 2.5 meters), while the portion 12 of superimposed helmet has a width B2 of 35 meters, and where the portion of the upper hull (with the girder) has a width of 40 meters. The width B3 of the hull in the railing constitutes approximately the same amount of width (40 meters) as the width of the boat that includes the lip. As mentioned before, the length of the hull can be 100 meters, that is, the width can be up to 35% of the length. With a hull design as indicated in this description, the drawbacks which are described in the introduction of the present specification in relation to the previously known forms of hull for drill ships are eliminated. An objective and a defining characteristic in the development of the present invention has been to produce a new but nevertheless developed practical design and simple construction of a single helmet with favorable dynamic properties. Single-hulled vessels specifically have a number of economic advantages compared to semi-submarine drilling rigs. In addition to the operational advantages of being able to transport large payloads, they have good space on board for oil storage, etc., and the drill ship is much cheaper to build than a semisubmarine drill rig. A drilling rig built with a hull in accordance with the principles which are presented in this specification will be able to have a construction price of 60-70% of the construction of a semisubmarine surveyor of the same specifications. This means savings of several hundred million crowns per vessel. This is due to the fact that, for example, a ship is well known and presents little risk and is easily constructed. A ship can be built in many shipyards which do not want to acquire the risk of building a complicated semisubmarine surveyor.

Figure 7 shows a graphic representation of the relationship (vertical movement) between the vertical movements and the wave height for different types of containers (single hull, according to the invention, and two types of semi-submersible platforms, called SEMISUB 1 and SEMISUB 2) as a function of the wave cycle. Curve 1 shows the percentage distribution of wave cycles in the North Atlantic on an annual basis (the abscissa is read against the ordinate on the right). It will be evident that the wave cycle that occurs most frequently is approximately 9 seconds, with a presentation of approximately 16.9%. The wave cycles in the 7-13 second interval are the ones that occur most frequently. After 17 seconds, the curve becomes uniform and such cycles occur only rarely. Along the ordinate on the left, the function of vertical movement of a vessel in meters of vertical movement is presented and it is read in relation to the height of the wave in meters. The horizontal line marks the point where the vertical movement is the same as the height of the wave, that is, vertical movement HEAVE = 1.0 The designation HEAVE-RAO means "operator of amplitude of response, a mathematical function which describes the movements of the boat in the ascending movements as a function of the waves that are presented.

In the other three curves in the diagram, the response for a container according to the invention (ie, a ship with walls, inner lips, spaces including perforations and outer lips), and two numbered semisubmarine probes 1 and 2 are shown. (semi-submerged platforms of different size). It will be evident that in cycles of up to 6 seconds, the construction is almost stopped (response = 0). During the wave cycle interval that occurs most frequently, that is, up to 13 seconds, the three curves rise uniformly, but for the two semisubmarine probes the curve descends again forward to cycle 20-21, where it again occurs an ascending stage, and the curve goes to the answer line for HEAVE = 1.0. This means that the semisubmarine polling machines still oscillate with greater vertical movement than the wave itself, when the wave cycle exceeds approximately 21 seconds. Even if such large wave cycles occur rarely, they probably constitute 2-3 days of a year. Compared with this HEAVE-RAO value for the construction of the hull according to the invention therefore it will rise uniformly all the time with the wave cycle, but then the levels will not exceed the line 1.0.

The advantages which these curves show is that for a traditional single hull vessel one is able to obtain response values (HEAVE) in meters / meters which, over most of the wave spectrum, are as good as or better than the response for the semi-submersible platforms SEMISUBS 1 and 2. The wave cycle interval in which a single-hulled vessel has poorer responses than the SEMISUBS 1 and 2, that is, approximately 11-21 seconds, have the opposite or a probability of presentation, which is below 3% and decreases to 0%, on an annual basis. See the values for curve 1 (ordinate from the right). Such good response values previously have not been possible to obtain for single-hull vessels because such prior vessels have not been constructed in accordance with the invention, specifically a combination of internal through-wells where the walls comprise means to limit the flow of water inwards / outwards, in addition to the mounting of outer lips below the waterline on the hull. There are several advantages with helmet construction according to the invention. Applied as drilling and production vessels they can tolerate much larger deck loads compared to a conventional floating platform. It will be cheaper both its construction and operation, and are more flexible for transfers, and if necessary can be used without being anchored, and the need to provide boats to serve the drilling / production bank is much less than for a platform.

Claims (11)

1. A hull construction for a single-hull vessel, specially designed for drilling and production operations in mainly stationary position, the construction is characterized by the combination of the following individually known characteristics: a) one or more open wells that extend through of the hull for water flow in and out from the bottom, b) one or more walls of the well / wells comprising numerous elements for water flow retardation in the form of: one or more tabs / lips projecting towards outside the well wall which in one region prevents the water inflow area from the well and / or a number of hollow spaces that retard the inflow of water, which are connected for flow with the hollow space of the well by means of perforations, and c) where the exterior of the hull comprises a projection / longitudinal lip that projects horizontally outward preferably placed below the waterline of the hull.

2. The helmet according to claim 1, characterized in that the walls of the well form a lip projecting outwardly rounded throughout the well.

3. The hull shape according to one of claims 1 to 2, characterized in that several projections / lips projecting outwards mutually separated, possibly placed at different height levels in the wall of the ship's well.

. The hull shape according to claims 1 to 3, characterized in that, seen in cross-section, the lip extends from the wall of the well above: a) a flange extending horizontally in order to subsequently extend downwards and inward, towards the horizontal keel portion with a largely rounded circular portion, and / or b) as a downward sloping flange which is formed by stepwise graduation forming a polygon (trapezoidal) cross-section towards the keel portion horizontal horizontal and / or c) as an outstanding part having a circular cross section.

5. The hull shape according to claim 1, characterized in that the waterline area of the well constitutes 3-40%, preferably 8-30% and especially preferred 15-30%, and particularly preferably 15% of the Total waterline area of the ship.

6. The hull shape according to one of the preceding claims, characterized in that in a horizontal direction, the projections / lips project outwards from the walls of the well a distance in the range of 1.5-5 meters.

7. The hull shape according to claim 1, characterized in that for a boat with a length of approximately 180 meters, the projection / longitudinal lip projects on each side of the hull a distance of 1.5-5 meters outward from the side of the hull , and preferably at least 5 meters.

8. The hull shape according to one of the preceding claims, characterized in that, seen in cross section, the projection / lip extends from the wall of the well above: a) so that it extends horizontally the rim in order to subsequently extend downward and inward, towards the horizontal keel portion with a mainly rounded circular portion and / or b) as a downward inclined flange which is gradually graduated to form a polygon (trapezoidal) cross section towards the horizontal keel portion underlying and / or c) as an outstanding part with a circular cross section.

9. The hull shape according to one of the preceding claims, characterized in that the hollow space is formed by a plate which is placed mainly parallel to the well wall and at a distance from it, for example, placed upwards of the upper side of the shaft. lip, so that the well wall and lip and plate define a space in which a portion of the well water can flow in and out through several holes in the plate.

10. The hull shape according to claim 9, characterized in that the plate is a perforated wall / with holes, preferably with circular perforations, which constitute up to about 10-30% of the total wall area, and especially preferred openings / holes of the wall constitute approximately 25% of the combined area of the wall plate.

11. The use of the hull shape according to claims 1 to 11, for vessels, especially vessels for drilling after and / or production of oil and gas, or for seismic investigations where the movements of the vessel, especially movements, must be damped vertical as a result of the difficult sea. SUMMARY OF THE IN IN ION A hull construction is provided for a vessel (10) with a single hull, designed especially for drilling and production operations in largely stationary positions. The hull construction is characterized by a combination of individually known features: a) one or more open wells (26, 28, 30) extending through the hull for the flow in and out of water from below, b) one or more walls (36) of the well / wells (26, 28, 30) comprising several water flow retarding elements in the form of one or more projections / lips (34) projecting out of the wall (42). ) of well, which, in one region, limits the water inflow area of the well (26, 28, 30), and / or several hollow spaces (42) of water inflow delay which are connected to flow with the hollow space of the well by means of perforations (44) and c) the exterior of the hull comprises a longitudinal projection / lip (34) projecting horizontally outwards preferably positioned below the line (20) of flotation of the hull (10). ). 1/5 OR