NO338221B1 - System for transporting cuttings - Google Patents

Abstract

A method and apparatus for processing drill cuttings, the method comprising obtaining drill cuttings from at least one of a shale shaker, hydrocyclone, centrifuge or drill cuttings dryer (801), measuring the moisture content of the drill cuttings preferably with a moisture sensor (821) to obtain a moisture value, comparing the moisture value to a predetermined threshold and conveying the drill cuttings in a dry cuttings route (825) if the moisture value is below the predetermined threshold or conveying the drill cuttings in a wet cuttings route (810) if the moisture value is above the threshold.

Description

SYSTEM FOR TRANSPORTING DRILLING CUTTINGS

The present invention relates to a system for transporting drilling cuttings from drilling cuttings processing equipment to a storage tank, and in particular, but not exclusively, for transporting wet drilling cuttings produced in the design of an oil or gas well, or for drying wet drilling cuttings before transporting the drilling cuttings over a considerable distance, and then transport the dry cuttings.

When drilling a borehole for an oil or gas well, a drill bit is arranged at the end of a drill string, and this is then rotated to drill the borehole. A drilling fluid known as "drilling mud" is pumped through the drill string to the bit to lubricate the bit. The drilling mud is also used to carry the cuttings produced by the drill bit and other solids to the surface through an annulus formed between the drill string and the borehole. The drilling mud contains expensive, synthetic, oil-based lubricants, and it is therefore common to recover and reuse the used drilling mud, but this requires that the solid components be removed from the drilling mud. This is achieved by treating the drilling fluid. The first part of the process is to separate the solids from the solids-saturated drilling fluid. This is achieved, at least in part, by the use of a vibration separator, such as the vibration screening devices described in US 5,265,730, WO 96/33792 and WO 98/16328. Process equipment for further processing, such as centrifuges and hydrocyclones, can be used to clean the sludge of solids. The solid components are covered by pollutants and residues.

The solid components that come out of this process, in this document called "drilling cuttings", are treated to remove essentially all residues and pollutants from the solid components. The solids can then be disposed of in a landfill or by dumping it in the sea in the area where the solids came from. Alternatively, the solid can be used as material in the building and construction industry or for other industrial applications. The solid components are usually treated on land, using methods such as those described in e.g. the present applicant's corresponding PCT application, Publication No. WO 03/062591. This process equipment may be located near an oil or gas platform. Alternatively, the process equipment can be located on land, far away from an offshore oil platform or far from a land-based rig. The solid components must therefore be transported from the outlet of the vibrating sieves, centrifuges and hydrocyclones, and to the equipment that will process the solid components. In some previously known systems, oily drilling cuttings are loaded into vessels, containers or drilling cuttings boxes that are lifted aboard supply ships. This can alternatively be partly carried out using a chute where a driven transport screw is arranged which transports the wet solid to storage tanks. Such a system is described in the present applicant's corresponding PCT application, publication no. WO 03/021074. After processing in a vibration screening device, drilling cuttings can contain approx.

10 to 20% by weight moisture (oil, water).

Today, it is often desirable and/or a statutory requirement that recovered drilling cuttings be transported to a treatment facility on land to remove the essentials of all oil and all pollutants, so that the drilling cuttings can be disposed of or used in an environmentally friendly and safe manner. Environmental bodies around the world are approaching a "zero discharge in pps" policy when it comes to offshore platforms. It is common for drilling on an offshore oil platform to take place continuously, and cuttings are stored on the platforms until they can be transported away using so-called supply ships, which pick up the oil-containing cuttings and transport them to another location for further processing. There is a need for efficient storage of oil-containing drilling cuttings on the platform, and also a need for efficient storage of the drilling cuttings on board supply ships. The solids can be added to a fluid such as water, so that a slurry is formed. The slurry can be pumped into ships, trucks, containers or sacks for transport to the treatment site. Alternatively or additionally, the wet solid from the storage tanks can be transported through pipes using compressed gas, as described in PCT publication no. WO 00/76889.

Previous publications describe various methods for transporting dry solids with low slurry density and low particle density, and non-continuous transport of wet material with high slurry density and high particle density, using continuous positive pneumatic pressure. Many low density slurries will typically have air-entrained particles with a specific gravity of less than 1.0. Previous publications describe various methods using suction transport of solids with high particle density and low particle density.

Thus, the problem of transporting, buffering and storing material with low slurry density and high particle density, and especially, but not exclusively, drilling cuttings from oil fields and other oily/wet waste materials, is handled by using a continuous, positive pneumatic pressure.

WO 00/76889 describes a system according to the introduction to claim 1, where drill cuttings are transported in the form of a non-free-flowing mass, where the system comprises a pressure tank with an outlet part shaped like a conical funnel, where the cone angle is sufficient to cause a mass flow. The cuttings are stored on a platform and on board a supply ship in ISO-sized storage tanks with a conically shaped funnel outlet, so that the ISO-sized tanks can be emptied from the platform to the ship and from the ship to the port. These ISO tanks are very tall and the amount of cuttings stored in them is limited due to the lower converging parts of the tanks.

German patent no. DE 40 10 676 describes an apparatus for transporting sewage sludge or concrete. The apparatus comprises a pressure tank with an inlet opening and a screw conveyor underneath. There are paddles that act as agitators and forcibly fill the screw conveyor through an opening in the pressure tank. The screw conveyor moves the sewage sludge or concrete into a nozzle where compressed air is used to move the sewage sludge or concrete in an uninterrupted flow through a pipe.

British Patent No. GB-A-2 330 600 describes a system for transporting drilling cuttings from a platform to land. The system includes the steps where the oily cuttings are mixed with a mud to form a slurry; the slurry is stored in holding tanks on the platform; and then the slurry is pumped to holding tanks on a ship for transport to shore.

WO 03/021074 describes, among other things, an apparatus for the transport of solid waste substances, where the apparatus comprises an upstream supply device for waste substances; a feeding device that transports waste materials from the waste supply device and to a compressed air conveyor, which compressed air conveyor comprises a pipe where the waste materials are transferred from the feeding device to a downstream waste collector, and where said pipe is connected to at least one blocking sensor and an electronic data processing device that processes output data from the blocking sensor.

WO 82/03066 describes a method of unblocking a conveyor for particulate materials, comprising introducing air into the tube at several spaced locations to reduce the length of the blocking material.

US-A-6,585,115, Reddoch, Baker Hughes Incorporated, describes several methods and apparatus for transferring "dry" cuttings from oil and gas wells, including: 1. A fluid separator having a chamber and a vertically aligned helical screw therein. A vacuum is used to draw the cake into the chamber. The sawdust is obtained from the overflow from a vibrating sieve. The helical screw compresses the cuttings to extract more fluid from it, and this fluid is forced out through the screen surrounding the helical screw. A valve is located below the helical screw to selectively separate out dry cake. The dry cake is preferably further dried to less than 3% by weight of fluid using a centrifuge. 2. A screw pump, gas pumping means, progressive cavity pump and positive displacement pump to move cake around an oil platform.

US-A-6,345,672, Dietzen, describes a method and apparatus for removing drilling cuttings from an oil and gas drilling rig, the apparatus comprising a horizontal cylindrical tank of circular cross-section which has a twist drill located longitudinally in the bottom of the tank to move cuttings towards a outlet port and draw it with vacuum through an outlet tube connected to the outlet port. Compressed air is injected into the discharge pipe to assist the flow of cuttings through it. Drilling cuttings can be ground before being stored in tanks. The tanks can be located on a rig or a supply ship, or they can be floating and towed by a tugboat.

US-A_6,045,070, Davenport, describes an apparatus for treating drilling cuttings, and

particularly re-injection of cuttings, as the apparatus comprises a sorting mill with a funnel into which the drill cuttings are fed from the end of the screw conveyor. A mud carrier fluid and viscosity-promoting polymer are added to the drill cuttings in the funnel. The solids in the sludge are ground in the grinder. A displacement pump is used to transport the sludge from the screening mill to the injection pump to re-inject the sludge back into the well or to be ground again. It is also described, although not in connection with processing drilling cuttings, a compressed air conveyor.

GB-A-2,318,370, Stewart, describes a method and apparatus for disposing of drill cuttings, the apparatus comprising a vibrating screen, a screw filter press for removing excess cuttings from the drill cuttings and a transport container with rods mounted on a rotating shaft. The transport container also has a screw conveyor located at the bottom of the transport container in a chute having an outlet valve located at the end. The transport container is transported to an unloading place on the rig, as the cuttings are released from the container, formed into a drilling mud and injected into a well again.

EP-A-0,662,436, Groffman, discloses a container for sewage sludge in which the container has a flat bottom, an outlet opening therein and a scraping sliding frame for moving the sludge on the flat bottom into the opening. A screw conveyor is placed in a channel below the outlet opening.

DE4010676, Ihlefeld, describes a pressure vessel for containing wet cement, the vessel having a screw conveyor at the bottom leading to an outlet opening which is connected to a pipe. A positive compressed air fluid is supplied through a concentric piece between the outlet opening and the pipe to push the cement through the pipe.

According to the present invention, a system is provided for transporting cuttings from cuttings processing equipment to a storage tank, the system comprising a small pressure tank and at least one storage tank, the small pressure tank containing cuttings material and gas under positive pressure, a source of compressed gas, an inlet for compressed gas for to apply pressurized gas to the drilling cuttings material, the small pressure tank having a first opening through which drilling cuttings material can be fed into the small pressure tank, and a second opening through which drilling cuttings material can flow out of the small pressure tank and into a positive compressed air transport channel for transporting the drilling cuttings material to said at least one storage tank, in that said at least one storage tank comprises a pressure tank that accommodates drilling cuttings material and gas under positive pressure, a pressurized gas inlet to the storage tank to apply pressurized gas to the drilling cuttings material, in that the pressure tank has a first storage tank opening through which drilling cuttings material can be fed into pressurized the anchor and a second storage tank opening through which drilling cuttings material can pass out of the pressure tank. The characteristic feature of the invention is that the system further comprises a rotary drill which is inside the small pressure tank and which is movable in the vicinity of the second opening, the small pressure tank further comprising two sides which slope towards each other to facilitate the passage of the exposed drill cuttings for compressed gas through the second opening into said positive compressed air transport channel and a mechanical movement device in the storage tank, the storage tank's direction of movement comprising a movement element in the storage tank and a storage tank twist drill inside the pressure tank, where the twist drill can be moved close to the second storage tank opening to make it easier for the cuttings material exposed to compressed gas to flow through the second storage tank opening.

Also described herein is an apparatus for selective storage of drilling cuttings material, preferably during the process of transporting drilling cuttings, comprising a tank with a first opening through which drilling cuttings material can be fed into the tank, and a second opening through which drilling cuttings material can be fed out of the tank, characterized by the apparatus further comprises a movement device, the movement device comprising a movement element in the tank, which can be moved near the second opening to make it easier for the cuttings material to flow into the second opening. The movement device is preferably a mechanical movement device.

The system preferably further comprises a box for receiving cuttings material that flows through the second opening, the box having a cuttings outlet which is connected to a transport channel. The box can be any space into which the cuttings can fall or be pushed down on the way into the transport channel. The box can form part of the transport channel. The transport channel can be a rigid pipe or a flexible hose, preferably with a diameter of between 50 and 200 mm, more preferably 100 to 150 mm, and most preferably approx. 125 mm in diameter.

It is an advantage if the system also includes a compressed gas inlet where compressed gas can be used against the cuttings to facilitate the movement of the cuttings through the cuttings outlet. The compressed gas inlet is preferably in line with the cuttings outlet. The gas is preferably air or an inert gas such as nitrogen. It is an advantage if the storage tank's compressed gas inlet is located in the pressure tank, to allow gas under positive pressure to flow therein to prevent cuttings from being blown back from the casing into the pressure tank during emptying. Thus, an inlet for compensating compressed air is preferably placed in the pressure tank to provide an even pressure which prevents drilling cuttings from being blown back from the box and into the storage tank during emptying. The equalization pressure is preferably equal to the pressure in the box, but the equalization pressure can be slightly lower or higher than the pressure in the box.

It is an advantage if the small pressure tank and the storage tank have been pressure tested to withstand a working pressure of at least 2 bar, more preferably at least 4 bar and most preferably at least 7 bar. The storage tank preferably further comprises an air valve which prevents the tank from being overloaded by the pressure in the tank.

A transport channel is essentially kept full and thus makes it possible to maintain a steady supply or dosage rate. The transport channel can be supplemented in certain aspects

drilling cuttings in such doses that the transport channel is full, so that the drilling cuttings move along the transport channel as one long mud plug. Alternatively, the drill cuttings can form a plurality of plugs along the transport channel, separated by pockets of pneumatic fluid. This is controlled through the speed at which the drill cuttings are dropped or pushed into the transport channel, known as dosage rate or dosage amount. The dosing rate is dictated by, among other things, the consistency of the drill cuttings, the pneumatic pressure used against the drill cuttings, and the diameter of the transport channel, so that a predetermined transport rate is achieved. In a preferred embodiment, a quantity of thirty tonnes of drilling cuttings is transported per hour from the storage tank, through the transport channel and on to a receiving location.

The cuttings stored in the storage tank can be dry or wet. Wet cuttings contain water and/or oil. Wet cuttings can be free-flowing, non-free-flowing or pasty. Drilling cuttings are often wet after being processed in a vibrating screening device. The drilling cuttings can be dried using a vortex dryer, as described in this document, to produce essentially dry drilling cuttings which in some aspects can be free-flowing, solid components that follow Newton's laws of flow.

It is an advantage if the movement device further comprises a drive device which is connected to the movement element in order to move the movement element. The second storage tank opening preferably has a length, and the movement element comprises an elongated element with a length which is preferably substantially equal to or greater than the length of the second opening. It is an advantage if the elongate element has an edge which is shaped so that it facilitates the movement of drilling cuttings material to the other opening. The elongate element preferably has a front edge which is bevelled to make it easier for the elongate element to move under a pile of drill cuttings, and a rear edge which is designed so that it picks up drill cuttings to move them towards the other opening, i.e. the rear edge is preferably at right angles to the direction of movement of the elongated element, it can be step-shaped and/or concave, advantageously has a bucket edge for shoveling drill cuttings into the opening, and is most preferably a sliding frame.

The second storage tank opening preferably has a width, and the movement element can be moved back and forth across the width. It is an advantage if the movement element comprises a frame with a steering shaft which is attached to at least one curved outer peripheral part. The movement element preferably comprises a frame with an outer peripheral part which is essentially eye-shaped. Alternatively, a rack with a drive or a rotating disc with an arm placed on its circumference can be used to convert a turning movement into a reciprocating movement, in the same way as a crankshaft in a car engine. Such a thrust element can be used in many different tanks, including but not limited to a mass flow funnel, a core flow funnel, a flat-bottomed funnel, a so-called "chisel plane" type flow-through tank, or a conical tank.

The twist drill can form part of a screw conveyor, and can be any type of screw that moves drill cuttings. The twist drill is preferably placed under the second opening. The rotary drill is preferably placed in a chute. The chute can have a cover to prevent drilling cuttings from entering the chute when the device is out of use for a long time. The cover can optionally be moved with the movement element. The cover can be perforated or non-perforated. The box is preferably located at the outlet end of the drill. It is an advantage if the device also includes a motor that rotates the drill. It is an advantage if the device further comprises fingers which may be knife-like, placed at the end of the drill, to make it easier to detach the cuttings from the drill and preferably to make it easier to break up lumps of cuttings. The rotary drill preferably comprises at least one blade with a constant pitch. The drill can advantageously or alternatively include at least one blade with a variable pitch.

It is an advantage if the system further comprises a cover which is chosen to be used to cover the second storage tank opening. The cover preferably covers the second opening pneumatically. It is an advantage if the cover is made of a sieve, so that it is possible for gas to flow through. The cover is preferably connected to the direction of movement and moves with it.

The storage tank preferably has an essentially flat interior bottom. The storage tank bottom can be flat and/or mainly horizontal. By using a non-conical funnel or pressure tank in some embodiments according to the present invention, bridging can be prevented and reduced compared to the bridging that can occur in some conical tanks. In one aspect, the sliding element(s) is/are substantially flat (flat), so that they can be slid over a flat bottom. In some aspects, the push element is rigid. The flat bottom is preferably circular and has a diameter of between 1.5 and 4 metres, and in one specific embodiment has a diameter of 2.7 metres. The flat bottom or the lower part of the tank can be provided with a plurality of small air holes that let compressed air through to supply air to the cuttings, so that it is easier to transport the cuttings through the other opening or down a chute if such exists .

It is an advantage if the storage tank has at least one essentially vertical wall. The storage tank preferably has a dome-shaped top. It is an advantage if the storage tank is essentially cylindrical with an essentially circular bottom, where the second opening goes through the essentially circular bottom.

It is an advantage if a valve is arranged in the first opening which controls the inflow of drilling cuttings. The valve can be of the type described in GB-A-1 539 079 or US-A-3 586 383.

The first storage tank opening preferably has a non-return valve which prevents drilling cuttings from flowing out through the first storage tank opening.

The small pressure tank may be of any suitable type to facilitate the passage of cuttings material; wedge-shaped, plane-flow, chisel-shaped (chiseL), pyramidal, square or other.

The pressure tank preferably has a conical funnel section. The conical funnel part advantageously has a cone angle and forms a lower part of the tank, and the cone angle is below the critical value necessary to achieve a mass flow of drilling cuttings material.

It is an advantage if the small pressure tank has a capacity of between 0.15 cubic meters and one cubic meter, so that the small pressure tank is preferably not used to store drilling cuttings, but is used for continuous transport of drilling cuttings. The small pressure tank can be as small as 0.05 and 0.2 cubic meters.

The storage tank preferably has a capacity of at least three cubic metres, as it is preferably used to store drilling cuttings, either on a platform or on a barge, boat, truck, train or in a storage area on land. The storage tank is usually between 10 and 30 cubic metres, and most preferably between 12 and 16 cubic metres.

It is an advantage if the system also includes a moisture meter that measures the moisture content in the drill cuttings. The system preferably further comprises a funnel, where the moisture meter is placed in the funnel. It is an advantage if the moisture meter is located in the small pressure tank. The system preferably further comprises a control unit which collects data from the moisture meter, and a device which diverts the drill cuttings as a reaction to the data. The device preferably comprises a diversion valve which diverts the drill cuttings. It is an advantage if the device comprises a screw conveyor, preferably with a motor that drives the screw conveyor, and which can optionally rotate the conveyor clockwise and counter-clockwise to reverse the drilling cuttings transport from a first direction to a second, opposite direction.

It is an advantage if the storage tank stores wet cuttings. Preferably, the system further comprises a storage tank for storing dry drilling cuttings. It is an advantage if the storage tank for storing dry cuttings is the internal bulk tank on a drilling rig. The storage tank for storing dry cuttings is preferably the internal hold of a ship or barge. The storage tank for storing dry drilling cuttings is preferably a further storage tank according to the invention.

It is an advantage if the storage tank according to the present invention is fed using a blowing tank. Alternatively, in addition to or instead of blow tank(s), a pump, such as a displacement pump or a cement pump (or pumps), may be used to move the drill cuttings, for example from vibrating screens or a chute or a vortex dryer to the storage tanks. The floor area and total available space around vibration screening devices is often limited, and the storage tanks or containers that will contain the drilling cuttings are therefore often placed relatively far from the screening devices, usually several tens or hundreds of meters.

In order to provide a better understanding of the present invention, reference will now be made by way of example to the accompanying drawings, where: Fig. IA shows a storage tank for a system according to the present invention, seen from above and along line I-1 in Figure IB; Fig. IB is a cross-section of the storage tank of Fig. IA, seen from the side; Fig. 1C shows another embodiment of a storage tank according to the present invention, seen from the same angle as Fig. IA; Fig. ID is a top plan view of an alternative part for the storage tank shown in Fig. IA; Fig. 2 is a schematic diagram showing the system according to the invention in operation; Fig. 3 is a schematic cross-section showing a previously known feed tank used in a system which is not part of the present invention; Fig. 3A is a cross-section of a small pressure tank of a system according to the present invention seen from the side; Fig. 3B is an end view and fig. 3C is a side view of the small pressure tank shown in Figure 3A; Fig. 4 is a schematic side view of a tank in a system which is not part of the present invention; Fig. 5A is a cross-section, taken along line VA-VA, of a frame part shown in Fig. IA; Figs. 5B to 5D are alternative forms of the cross-section of the frame part for the storage tank of Fig. IA; Fig. 6 is a schematic diagram of a storage tank arrangement according to the present invention; Fig. 7A and 7B are sectional perspectives of a further embodiment of a storage tank according to the present invention seen from above, showing steps in its use; Fig. 7C is a sectional perspective of a further embodiment of a storage tank according to the present invention seen from above; Fig. 7D is a cross-section of the storage tank of Fig. 7C seen from the side, without drilling cuttings in; Fig. 7E is a cross-section of the storage tank of Fig. 7A seen from the side, with drilling cuttings in; Fig. 8A is a schematic side view of part of a system according to the present invention; Fig. 8B shows a part of a system shown in Fig. 8A seen from above; Fig. 9A is a schematic diagram of a small pressure tank according to the present invention; Fig. 9B is an end view of a portion of the small pressure tank of Fig. 9A; Fig. 9C is a side view of a portion of the small pressure tank of Fig. 9A; Figs. 10, 13 and 15 are schematic diagrams showing systems according to the present invention

invention; and

Figs. 11, 12 and 14 are schematic diagrams showing a feeding device for a small pressure tank in

a system according to the present invention.

Referring to figures IA and IB, a storage tank 1 of a system according to the present invention has a generally cylindrical pressure tank 2 with a circular cross-section, a generally circular, flat bottom 3 and a dome-shaped top 4. flat bottom 3 and the dome-shaped top can be designed in one piece with or welded to the wall of the pressure tank 2.

The pressure tank 2 can be made of steel of the type defined by British Standard 1501 224-49B, and can be designed to withstand an operating pressure of between one and 20 bar, and in one particular aspect seven bar. The dome-shaped top 4 optionally has an inlet 5 with an attached supply line 6, which in one particular aspect has a diameter of 52 mm (two inches), for supplying pressurized gas such as air and/or nitrogen and/or a other inert gas, which is used against the top of the drill bit DC in the tank. The dome-shaped top 4 is also provided with a cuttings inlet 7 which is provided with a valve 8, for example a gate valve or a full flow (full bore) ball valve, which can be manual or remotely controlled, for example by means of a stepper motor. Alternatively, the drill cuttings can be introduced through the inlet 7 using any known system, for example, but not limited to, a conveyor system.

The cuttings inlet 7 has, in one particular aspect, an internal diameter of 125 mm (five inches). The flat base 3 has an opening 9. The opening 9 can have any suitable shape, seen from above, and is, as shown, usually rectangular. A tube 10 has an opening which fits together with and is fixed around the circumference of the opening 9 in the flat bottom 3, so that a pressure-tight closure is formed. The pipe 10 can be welded to or otherwise designed with the flat bottom 3. The pipe 10 optionally accommodates a twist drill, which in one aspect is a screw conveyor 11 which is rotatably mounted in the pipe 10 and is driven by means of a hydraulic motor 12 with variable rpm.

The motor 12 can alternatively be electric, petrol-driven, pneumatic or driven in some other way. The screw conveyor 11 has a shaft 13 and a spiral or helical shape

blade 14. The helical blade 14 has, in one aspect, a diameter of between 150 mm and 600 mm (six and 24 inches), and in one particular aspect has a diameter of between 350 mm and 400 mm (14 and 16 inches). The shaft 13 has a first end which is connected to the hydraulic motor 12 with variable speed, and a second end which is rotatably arranged in a bearing 15 in an end wall 16 in the pipe 10. The pipe 10 extends past the outer edge of the flat bottom 3. The helical blade 14 runs essentially across the entire diameter of the flat bottom 3 and extends into a part of the tube 10 which extends past the outer edge of the flat bottom 3, where the blade ends. In some aspects where there is no drilling device or conveyor 11, pressurized gas in the tank is used to convey the material in the tank to the outlet opening.

Four, six or more radially projecting fingers 17 (two shown) extending from the shaft 13 (or may be connected to the inside of the tube 10) are spaced from the end of the helical blade 14. The part of the tube 10 which protruding beyond the outer edge of the flat bottom 3, has an outlet box 18 with a lower chamber 18a, where a compressed gas inlet 19 is arranged under the end of the helical blade 14. The outlet box 18 tapers from an upper part which has a width of substantially equal to the diameter of the pipe 10, to a smaller width that substantially equals the diameter of an outlet 20. The air supply inlet 19 leads into the lower chamber 18a in the outlet box 18 and lies in line with a cuttings outlet 20. The cuttings outlet 20 has one particular aspect has an internal diameter of 125 mm (five inches) and is attached to a drill cuttings conveyor (not shown) of the same or similar internal diameter, where this may be a flexible hose or a rigid pipe.

Inside the pressure tank 2, a sliding frame 21 is placed on the flat bottom 3 around opening 9. The sliding frame 21 can have any desired shape, seen from above, which helps to move drilling cuttings towards the opening 9. In one aspect, the frame 21 has two symmetrical curved parts 22 and 23 which make an eye shape arranged on four arms 24 which are connected to a central part 25. The curvature in the two symmetrical curved parts is slightly less than the curvature along the outer edge of the flat bottom 3. External edges 27 of the two symmetrical, curved parts 22 and 23 and of the four arms 24 are beveled in one aspect, while internal edges 28 (see figure 5A) which face the opening 9, are at right angles to the plane of the flat bottom 3. The curved parts 22, 23 have a flat underside 29. The bevel cutting angle is in some aspects between 45 and 20 degrees in relation to the flat underside 29. This can be clearly seen in figure 5A. It is within the scope of the present invention for a frame or part to be of such size and configured to move over the opening 9 of any shape, for example but not limited to a part 102 as shown in Figure 1C, or a substantially circular frame, as shown at frame 21a in Figure ID. The opening 9 can have any desired shape with any desired width and length; and, as shown, may be approximately the same width as the drilling device located below the opening (or the drilling device may be slightly wider than the opening).

A hydraulically operated piston and cylinder assembly 26 is connected at one end to the wall or flat bottom 3 of the pressure tank 2, and at its other end to the slide frame 21, to cause the slide frame 21 to move back and forth across the flat bottom 3 within the pressure tank's 2 boundaries, as shown by the arrow. Alternatively, some of the frame's movement device can be located outside the tank.

The curved parts 22 and 23 may have different profiles so that they can slide under the drill cuttings DC as they move away from the opening 9, and act as a rake or a bucket that scoops, digs or moves the drill cuttings into the discharge opening 9. In one aspect, the space around the conveyor 11 in the pipe 10 is kept essentially full, so that a uniform dosing rate can be maintained, depending on the speed of rotation of the conveyor 11, during the transport of drilling cuttings from the storage tank.

Figures 5A to 5D show an exemplary, but not the only possible list of alternatives for the curved parts 22, 23. Figure 5b shows a curved part 22 (part 23 is equivalent) with a beveled front side 31 and a concave back side 32. Figure 5C shows a curved part 22 (or 23) with a bevelled front side 32 and a stepped rear side 33 with a shoulder 34. Figure 5D shows the curved part 22 (or 23) with a stepped front side 35 and a slightly angled rear side 36, so that in use, an acute angle is formed between the angled back 36 and the flat bottom 3.

The storage tank 1 is in one aspect attached to a skid frame (skid) not shown to facilitate the transport of the storage tank 1 on trucks, supply ships, railcars, and on land and offshore platforms. The skid frame may also comprise a frame surrounding the storage tank 1, which may be of a standard ISO size to make it easier to transport on ships, trains and trucks equipped with fasteners with ISO distances. The height of the storage tank 1 mounted on the skid frame is in one aspect 3.26 meters, the length of the skid frame is 3.95 meters and the width is 2.9 meters. It should be noted that the height of the tank is very small compared to the internal volume.

A pressure relief valve 8a is placed on the pressure tank 2 and is set to between 10% and 20% above normal operating pressure, which is preferably seven bars. There may also be a removable and/or movable hatch 8b in the wall of the pressure tank 2 which provides access for inspection, inspection and maintenance.

Figure 1C shows a storage tank corresponding to storage tank 1, except that instead of a sliding frame 21, this has a raking device 100 and associated movement device. Like reference numbers indicate like parts. The raking device 100 (or the sliding frame 21 etc.) can be used with any tank or container described in this document. The rake device 100 has a part 102 on a shaft 104 which is moved back and forth over the opening 9 by means of a movement device 110. A drive mechanism 112 (for example any suitable motor, or reciprocating mechanism such as, but (not limited to, a piston/cylinder assembly such as that of Figure IA) moves the shaft 104 back and forth to move the member 102 over the opening 9, so that the drill bit moves more easily down the opening 9. Optionally, a vibration mechanism 114 outside the tank 2 can vibrate the shaft 104 to vibrate the part 102 and/or induce vibrations in the drill bit through the tank 2. A vibration mechanism 106 may possibly be arranged on the shaft 104 inside the tank 2 to vibrate the shaft 104 and the part 102, so that the drill bit moves more easily. Optionally, a vibration mechanism 108 on the part 102 can promote movement in the drill cuttings.

With reference to figure 2, wet cuttings come from a number of vibration screening devices 50 on a drilling platform.

The sieved, wet drilling cuttings fall from the sieves in the vibrating screening devices 50 into a chute 48. The wet drilling cuttings are moved along the chute 48 using a screw conveyor or a conveyor belt, or fall directly into a funnel. Wet cuttings are optionally fed into a dryer (not shown), such as a vortex dryer or a dryer of the type described in GB-A-2 297 702 to remove a significant amount of moisture. This is described in more detail in the corresponding PCT publication no. WO2004/083597 (PCT application no. PCT/GB2004/000762) and in the corresponding American application with serial number US 10/764 825, submitted by the present applicant. Under certain conditions, the moisture content in the cuttings is reduced to between one and five percent by weight, and under other conditions down to one percent by weight. "Wet" cuttings typically have an oil content of five percent or more, and "dry" cuttings have an oil content of less than five percent.

The wet or dry cuttings fall straight into a funnel 51 in a blow tank 52, shown in more detail in figure 3 which shows a system which is not part of the present invention. The blow tank 52 can be of the type described in GB-A-1 564 311. A valve 53, which can be of the type described in GB-A-1 539 079 is placed between the funnel 51 and a small pressure tank 54 as in one aspect has a capacity of approx. 0.3 cubic meters, although the capacity in other aspects is between 0.1 and one cubic meter; or larger or smaller. The size of the small pressure tank is in some designs dependent on how much space is available near the vibrating screening devices, and/or the number of cycles necessary to transfer the material at, for example, a rate of 30 tonnes per hour. hour. The small pressure tank 54 has a part 55 in the shape of a truncated cone. An air inlet 56 is arranged in an upper part of a wall in the pressure tank 54, and a cylindrical part 57 with a circular cross-section is arranged between the valve 53 and the wall in the part 55, which leaves a small annular gap 58 where compressed air can flow from the air inlet 56 into in the lot 55 with the shape of a truncated cone. This aspect is also described in US-A-3 586 383, in the name of William Trythall. A further valve 59 (which is optional) is arranged at the outlet end of the section 55, between the small pressure tank and a supply line 60. The further valve 59 can be of the same type as valve 53. The supply line 60 can be a flexible hose or a rigid pipe, and in one aspect has an internal diameter of 125 mm (five inches). In one embodiment, the further valve 59 can be omitted.

In one aspect, the valve 53 and the further valve 59 operate in cycles that are essentially phase-shifted, so that the valve 53 is open so that the small pressure tank 54 can be filled with drilling cuttings that moves by natural fall from the funnel 51, while the valve 59 is closed to prevent drilling cuttings from flowing into the supply line 60. The valve 53 is closed, so that a charge of drilling cuttings is trapped in the small pressure tank 54. The further valve 59 is opened. In one aspect, air at a pressure of between one and eight bar flows into the small pressure tank through slot 58 and puts the top of the cuttings charge under a positive pressure, so that a charge of cuttings can be pushed out into supply line 60. The further valve 59 can be opened with a small delay, so that the pressure can build up in the small pressure tank 54 before the valve is opened. The portion 55 having the shape of a truncated cone can be inclined to effect a mass flow, which is well known in the prior art, for example as described in publication US-A-3 604 758. Alternatively, the inner wall of the part having the shape of a truncated cone, be coated with a friction-reducing material, such as plastic, fiberglass, PTFE or a paint or varnish. The part 55 can alternatively be designed as a chisel, pyramid, wedge, transition or with a square opening. So to speak, the entire charge flows out into the supply line, and then the cycle repeats. Many cycles may occur per minute. The supply line 60 leads to the inlet 7 to the storage tank 1, which is located on the offshore platform 49 or close to the rig if it is a land-based rig, for example within 100-300 meters, although it can be located up to many kilometers (for example three or more ) away.

In use, the storage tank 1 is vented to the atmosphere, either by using a valve or by disconnecting the air supply line 6 from the air inlet 5. Cuttings charges flow into the storage tank 1 through the supply line 60 from the blow tank 52, and gradually fill the storage tank 1. The storage tank 1 can in one aspect take up to 12 cubic meters of drilling cuttings, but in other aspects can be of such a size that it can take between five and 20 cubic metres. When the storage tank 1 is full or nearly full, a valve (not shown) is opened in the supply line to divert the cuttings charges to another storage tank 61. Alternatively, the supply line can be disconnected from the cuttings inlet 7 and connected to the cuttings inlet of another storage tank 61. It can be arranged several storage tanks forming a series of 62 storage tanks.

At a convenient time when the supply ship or the vehicle that will transport the cuttings is in the vicinity of the row of storage tanks 62, for example when a supply ship 64 is moored at or less than three - four hundred meters from the offshore platform, one end of a flexible hose is connected 63 to one of the storage tanks 1, 61. The other end of the flexible hose 63 is connected to at least one storage tank 65 in a row 66 of storage tanks on board the supply ship 64. The storage tank 65 is in one aspect of the type described with reference to figure IA to ID. The flexible hose 63 can be equipped with flotation collars 67 to prevent it sinking into the sea.

Air supplied from a compressor not shown at approx. seven bar, and in another aspect four bar, is supplied through air supply hose 6, and into through the air inlet 5 to a space above the drill shaft surface in the pressure tank 2. The variable speed hydraulic motor 12 is activated to drive the screw conveyor 11. Air at, for example, approx. seven bar or slightly less, is supplied through an air inlet 19 in the outlet box 18. The same or a slightly lower pressure in the lower chamber 18a of the outlet box 18, compared to the pressure exerted over the cuttings, prevents the cuttings from being pushed backwards by the screw conveyor 11 and back into the pressure tank 2. The hydraulic piston-and-cylinder assembly 26 is activated to push the slide frame 21 back and forth to more easily move the drill cuttings into opening 9. The beveled edges on the side of the slide frame parts 22, 23, 24 ensure that when moving away from the opening 9, the parts of the sliding frame slide under the drill bit; and when moving towards the opening 9, the surfaces on the opposite side, which are either at right angles or have a bucket shape, pull the drill cuttings towards the opening 9. The drill cuttings move through the opening 9 and into the screw conveyor 11, which transports the drill cuttings further towards the lower chamber 18a in outlet box 18. Towards the end of the screw conveyor, a double spiral blade can be arranged which makes it easier to break up the drill cuttings. There can also be arranged fingers 17 which more easily break up the drill cuttings, which then fall into the discharge box 18 and are driven forward through the opening 20, into the flexible hose 63, and into the storage tank 65 on the supply ship 64.

The supply ship then transports the filled storage tanks 66 to shore. The storage tanks can be lifted by the supply ship 64 and placed on railway wagons, trucks with flatbed wagons

or right in the processing plant. Alternatively, the drilling cuttings can be released in the same way as that described above for the transfer of drilling cuttings from an offshore platform to the supply ship 64.

Figure 4 shows an alternative feed tank 70, which can be used instead of the blow tank 52 shown in Figure 3A in a system that is not part of the present invention. The tank 70 has a cuttings inlet 71 which leads from a funnel or other container (not shown) into a pressure tank 72 through a filling valve 73. The lower end of the pressure tank 72 is provided with a part 74 in the shape of a truncated cone, which leads to an outlet opening 75. The outlet opening has an outlet valve 76 which selectively opens and closes the opening 75. The outlet valve 76 and the filling valve 73 are in a fixed relationship to each other via a piston 77 which extends from the outlet valve 76 through the filling valve 73 and to a working cylinder 78. The piston 77 can is actuated pneumatically, hydraulically or by the use of a stepper motor to open and close the filling valve 73 and the discharge valve 76, which are arranged so that they operate essentially in an unsynchronized (phase-shifted) manner. An air inlet 81 is arranged at the top of the small pressure tank 72 where air is supplied under pressure, for example approx. seven bar, although it can be supplied at a pressure of between one and ten bar. Air holes 79 are arranged in the wall of part 74, so that cuttings are prevented from sticking to the wall, and to prevent bridging in the cuttings around the outlet opening. Radially from the piston 77 in the small pressure tank 72, fingers or stiff hairs/brushes 80 extend which are moved up and down together with the valves to brush away any drill cuttings that are stuck to the wall or have formed a bridge around the outlet opening (with the exception of the stiff hairs 80, the tank 70 is similar to a previously known tank).

In use, the filling valve 73 and the outlet valve 76 operate in cycles that are essentially not synchronous, so that the filling valve 73 is open so that the small pressure tank 72 can be filled with drilling cuttings that moves by natural fall from the funnel 51, while the outlet valve 75 is closed to prevent cuttings from entering the supply line 60. The filling valve 73 is closed, so that a cuttings charge is trapped in the small pressure tank 72. The discharge valve 76 is opened by activation of the piston 77, which closes the filling valve 73. Air at a pressure of, for example, between one and eight bar flows into the small pressure tank 72 and exerts an overpressure against the top of the cuttings charge to push a charge of cuttings out into the supply line 60. With a relatively small pressure tank, the valves can go through several cycles within a minute. With a pressure tank of 0.3 cubic metres, the valves will go through one or two cycles per minute or every other minute. The supply line 60 leads (as in Figure 2) to the inlet 7 of the storage tank 1, which is located on the offshore platform 49 or close to the rig if it is a land-based rig, for example less than 300 meters away, although it may be up to three or four kilometers away. Necessary ventilation is provided via a ventilation line 82.

This type of feed tank 70 was manufactured by Klockner-Becroit and is shown and described on pages 290-291 of the textbook "Pneumatic Conveying of Solids - a theoretical and practical approach", by Klinzing and Marcus, published in 1997.

Figure 6 shows a system 150 that brings improvements to systems and apparatus described herein, and also to systems described in US Patent 6,702,539, issued March 9, 2004, British Patent Application No. 9913909, filed June 16, 1999; US Patent Application 10/018,124, filed as application PCT/GB00/02158 on June 14, 2000, and European Patent EP 1,187,783 Bl, published on September 24, 2003.

Drilling cuttings flow through a pipe 157 and into containers 151. Each container 151 has a lower, cone-shaped part 155 with a lower opening 158. Near each opening 158 is a device 160 (which is similar to any device or any system described in this document, and which facilitates the movement of drilling cuttings from a tank or a container, for example, but not limited to the device described in figures IA to ID, for example with a movable frame 21 and/or a movable element 102 and associated movement mechanisms). The devices 160 move cuttings into a pipe 159 (for example, like pipe 19, US Patent 6,702,539) from which the cuttings can be fed into any suitable tank or container for transport, such as storage tanks 1 or the containers 31 shown in US-A-6 702 539. The containers 31 in said US-A-6 702 539 can have devices such as device 160 to facilitate the movement of the cuttings.

Compressed gas (for example air and/or nitrogen or another inert gas) can optionally be introduced into the tanks 151 at the same time as or after drilling cuttings have flowed into the tanks 151 through line 157. Compressed gas can optionally be introduced into the tanks 151 through a line 161 and is used against and/or over the drill cuttings, as previously described and/or discussed for any embodiment described in this document. Optionally, compressed gas is used against the devices 160 through lines 162, as described above in the system on figure IA. Compressed gas can optionally be used inside conduit 159 with one or more devices 163 to facilitate the flow of drilling cuttings material through conduit 159. Each of the devices 160 can optionally have a movement element (for example similar to frame 21 or element 102) which makes it easier to move cuttings out of tanks 151.

Figures 3A to 3C show a cuttings feeding device 470 for use in a preferred embodiment of the present invention (for example, from vibrating screeners or dryers to storage tanks), which has a small pressure tank 472 with a non-conical lower portion 474 having two inclined pages 475. In certain aspects, the small pressure tank has a capacity of between 0.15 cubic meters and one cubic meter, and in one particular aspect 0.33 cubic meters. Cuttings flow into the small pressure tank 472 from an overhead inlet funnel 476 through an opening 477. An inlet valve 478 (for example, a dome valve) selectively controls the inflow of cuttings into the small pressure tank 472, and in one aspect delivers a predetermined charge of cuttings, in one aspect for example 0.15 cubic meters to one cubic meter, and in one particular aspect 0.3 cubic meters.

Optionally, a movement element 482 (for example, similar to the above-mentioned movement element 102 or frame 21) can be moved by means of a movement device 484 (shown schematically; for example, any movement device described in

this document) to make it easier to move drill cuttings to and through opening 479 and out of the tank. A twisting device 480 is used (for example as any twisting device described in this document, and in one aspect similar to the conveyor 11, figure IA) with the small pressure tank 472.

Figures 7A, 7B and 7E show a storage tank 200 according to the present invention, which tank has a pressure tank 202 (for example similar to the storage tank 2, Figure IA) with a domed top 204, a generally cylindrical wall 206 and a bottom 208 Drilling cuttings 220 is fed into the tank 202 via an inlet 210 where the flow is controlled by a valve 212. Valve 212 can simply be a check valve of the flap type, which lets cuttings into the pressure tank 202, but does not let cuttings or compressed air out of the pressure tank 202. Optionally, compressed gas can be introduced through a gas inlet 214.

A frame 230 (for example corresponding to the frame 21, figure IA) is pushed over the bottom 208. The frame 230 includes a solid closing element 232, but this can be perforated or made of a screening material. The closing element 232 will selectively close an opening 234 in the bottom 208, where this opening is located above a screw conveyor 236 (similar to the conveyor 11, figure IA) which is rotatably mounted in a tube 240.

As shown in Figure 7A, the closing element 232 will stop, inhibit or reduce the flow of the screw conveyor 236 when the movement device 250 is in the fully retracted position. This closed position is assumed when the storage tank 200 contains drilling cuttings to be stored, to prevent drilling cuttings from being left in the screw conveyor pipe

240. If drilling cuttings are left in the screw conveyor 236 for too long, there is a risk that the drilling cuttings may settle and inhibit or prevent rotation of the screw conveyor when the tank is to be emptied of drilling cuttings. This closed position is also assumed when the storage tank 200 is empty, to prevent cuttings from falling into the screw conveyor 236 and being compressed in the screw conveyor 236. As shown in Figure 7B, the frame has been moved by means of movement device 250 (similar to any movement device described herein), and the opening 234 is no longer closed, and receives material flowing down from the tank 202. The flow of cuttings from the tank 202 to a cuttings outlet end 242 of the pipe 240 is facilitated by means of screw conveyor 236.

As shown by means of arrows 263 in Figure 7E, the conveyor 236 can be driven in reverse to circulate drilling cuttings in the tank 202, so that a more even cuttings mass is obtained. The arrows 264 indicate rotation of the screw conveyor 236 in the direction that causes cuttings to move from the tank 202.

The pipe 240 may optionally have an inclined end plate 247 which makes the drill cuttings move more easily towards the conveyor 236, and to facilitate the movement of the drill cuttings into and

inside the tank 202 when the conveyor is driven in reverse. The pipe 240 can optionally have an inclined end plate 248 placed near the outlet end which presses material down into an outlet chamber 245 and out of the pipe 240. Compressed gas can optionally be supplied in an inlet 243 to accelerate the movement of the cuttings from the outlet chamber and out of the outlet end 242 of the pipe 240.

As shown in Figures 7C and 7D, a storage tank 500 has a pressure tank 502 (for example

similar to the storage tank 2, figure IA) with a dome-shaped top 504, an essentially cylindrical side wall 506 and a bottom 508, and further comprises a plurality of air nozzles 561 through a bottom 508, through which nozzles compressed gas is injected into a tank 502 (in certain aspects upwards and/or downwards in the conveyor 536). The compressed gas supply to the nozzles 561 can be the same as to the inlet 514, or a separate compressed gas supply can be used. Figures 7C and 7D do not show the inlets for air and cuttings. The pressure fluid through the nozzles 561 can be at the same or a higher pressure than the pressure used to transport the cuttings. The cuttings are supplied with air by using a pressurized fluid through nozzles 561. This is important when dry cuttings are stored in the pressure tank 502. The dry cuttings are supplied with air and moved out through the screw conveyor 536. When the cuttings are supplied with air, they behave more like a fluid, and thus the transport of the cuttings becomes more predictable. It may also facilitate the removal of blockages in the conveyor, and may also be used to flush/clean the screw conveyor 536 at any convenient time, such as when the storage tank 500 is empty. The storage tank 500 may optionally include a plurality of air nozzles 562 which project into the pipe 540 and supply the pipe 540 with compressed gas to accelerate the movement of the cuttings, to prevent the cuttings from being compressed and unmanageable plug formations occurring. In one particular aspect, there is a plurality of air nozzles along the entire length of the tube 540. When the closure element 532 is in the closed position, air will penetrate past the edges of the closure element 532 (and, if perforated, through any perforations therein) and ventilate the drill cuttings moving past the frame 530.

A sliding frame (eg, similar to frame 230, Figure 7A) for handling wet cuttings, dry cuttings, or cuttings carrying moisture, allows the discharge rate (from the discharge end 242) to be regulated by regulating the amount of material flowing into the conveyor 236 Adding air to the cuttings, for example cuttings that have been dried using a dryer, facilitates the movement of the cuttings by making the cuttings behave more like a fluid, and makes the cuttings run more predictable.

Figure 8A shows an apparatus 600 in a preferred embodiment of a system according to the present invention for storing and transporting drilling cuttings [which may be wet, dry or carry with it moisture (steam)], where the apparatus optionally has a vortex dryer 610, feeding device 620 and a transport system 650. The vortex dryer 610 supplies drilling cuttings to the feeding device 620. The feeding device 620 has a small pressure tank 622 which delivers drilling cuttings to the conveyor 632. The feeding system 620 may in some aspects be similar to the device shown in Figure 3B.

Referring to Figure 8A, pressurized gas to facilitate the cuttings transport is supplied from a pressurized gas supply 602 through a line 627 to the small pressure tank 622, which is identical to the feeding device 470 shown in Figures 3A to 3C. Compressed gas from line 627 flows in a line 612 (where the flow is regulated by a valve 615) to an outlet box 624. A small amount of compressed gas is applied to the top of the small pressure tank 622 through valve 616 to prevent cuttings from being blown back into the small the pressure tank 622 from a feed auger at the bottom of the small pressure tank 622, which feed auger leads drill cuttings to the outlet box 624. Drill cuttings coming out of the outlet box 624 are driven by the pressure gas into and through the conveyor 632, from which the drill cuttings flow to the storage tank as the storage tank 1 which shown in Figure IA, or to a previously known drilling cuttings box placed on a platform, on land or on board a ship.

A plurality of pressure monitors 640 are spaced along the conveyor 632, and all include a pressure gauge and interface with a control system, such as a programmable logic controller (PLS) 680. A plurality of gas injection devices 690 are spaced along the conveyor 632, and selectively injects pressurized gas into the conveyor 632 under control of the PLC unit 680. The devices 690 are supplied with gas through a line 613. A valve 614 regulates the flow in line 613. Valves 614, 615, 616 are connected to and controlled by using the PLC unit 680. The motor-driven feed screw in device 600 is connected to and controlled using the PLC unit 680.

Each device 690 includes a check valve 691 through which air flows and into a conveyor 632, the check valves 691 preventing drill cuttings from flowing into and blocking pneumatic line 613; a controllable valve 692 which selectively regulates the flow of fluid into the conveyor 632; and a control valve 693 which selectively lets pressurized fluid through and into the conveyor 632 when the pressure difference between the line 613 and the pressure at point 640 is less than a predetermined difference, so that the pressure drop through the conveyor is kept constant.

The monitoring and regulation system provides maximum throughput in a safe manner, i.e. avoiding clogging and solids being pushed into a conveyor in an uncontrolled manner. The use of devices 690 and 640 ensures, in one aspect, that the cuttings "flow freely" and move in the conveyor 632. The pressure is monitored at strategic points along its entire length. The observed pressures are maintained by varying the drill bit feed rate and/or auxiliary air flow for consistent (and in some aspects optional) performance. In order to reduce the total pressure drop over the length of the conveyor 632 to a minimum, the length and/or density of a conveyor 632 which is in dense phase flow mode is regulated, whereby the entire cross-section of the conveyor is filled.

The denser a plug is, the higher the friction at the wall, and consequently higher pressure is required to drive the plug down through the conveyor 632. In addition, the relationship between plug length and the pressure required to drive a plug forward is exponential tielt, i.e. that the pressure required to drive a series of plugs separated by "pads" of air is much less than that required to drive a single plug of a length equal to the sum of the plug lengths in the series of plugs.

The feeding device 620 feeds measured plugs of drilling cuttings into the conveyor 632, which plugs have a size determined from the screw or twist drill's external diameter, shaft size and pitch. The feed rate is directly proportional to the speed of rotation of the screw. Local supply of air in the transport/discharge chamber ensures that the drill bit "flows freely", and the auger's speed control/stop/start function, which is controlled by the 680 PLC unit, provides precise control of the plug formation. This regulation is based on the pressure regime in the conveyor 632, which is strongly dependent on the flow form.

In one aspect, nominal set points are used in the conveyor 632 in terms of maximum pressure drop across the conveyor 632, where one is set to a low dilute phase value, for example two bar, which is used for dried cuttings, and the other, higher, to non-dried cuttings, for example four bar. In one particular aspect, the drill cuttings move in heavy phase through the conveyor at approx. 10 m/s; and in a thin or diluted phase, the drill cuttings move through the conveyor at approx. 30 m/s. The PLC unit 680 increases the screw speed to the speed necessary to feed the conveyor 632 in such a way that the pressure drop is maintained at a certain level between the units 690. For example; with four units 690 placed at an equal distance from each other along the length of a straight conveyor 632, the conveyor 632 is fed with a measured amount of cuttings from the feeder 620. The air supply 602 is activated, and the cuttings plug moves along the conveyor. For example, the starting pressure is set to four bar, and it is expected that the pressure at the end of the conveyor will be slightly above atmospheric when the plug reaches the end. The units 690 regulate the pressure in the line so that there is a relatively constant pressure drop between the units 690. The pressure drop is, for example, 0.5 bar between each unit, so that the pressure after the first unit 690 is regulated to 3.5 bar, after the second unit to 3.0 bar, after the third unit to 2.5 bar, and after the fourth unit to 2 bar, so that the pressure at the end of the conveyor 632 is expected to be approx. 1.5 bar, and one knows with a reasonable degree of certainty that the plug will come out of the end of the conveyor and enter the storage tank. If the pressure drop is within a certain percentage, for example 30%, and in one aspect 15%, and in one particular aspect 10% of what is expected, the regulator will open the line 613 and release compressed air, which is regulated by means of the regulator 693, into in the conveyor at the correct pressure.

A standard "PID loop" (Proportional-Integral-Differential) is used, so that if the pressure drop exceeds the desired set point, the speed of the feed screw will be reduced or stopped accordingly. Feedback from the pressure monitors 640 along the conveyor, strategically placed slightly upstream of pipe bends/vertical rises or other areas where turbulence is known to occur in the channel, is used to activate auxiliary air valves in the device 690 if this becomes necessary. An auxiliary air valve is placed at a turbulence point downstream of a pressure monitor, and if the pressure at the monitor falls below a certain percentage value in relation to the sensor located directly upstream of it, for example 80%, air will be supplied directly from source 602 via bypass line 613, which runs along the entire length of the channel, and into the associated auxiliary point. The pressure setting for the auxiliary air is set, for example, to 90% of the pressure value at the monitor 640 located directly upstream, and if this pressure is reached, auxiliary air will also be sent to the next injection point directly downstream, and so on. Each of the valves 691 can supply gas to an associated gas injection nozzle 699 (see, for example, Figure 8B).

Figures 9A to 9C show a feeding device 700 in a preferred embodiment of the system according to the present invention, similar to the feeding device 470 shown in Figure 3B, and which further comprises a funnel 720 with a vibration motor 725 that vibrates the buffer funnel part 721, and a further air injector 722 and a modified outlet box 753. A control system 701 is connected to sensors in the funnel part 721 and the pressure tank part 740. The funnel 720 comprises the buffer funnel 721; an optional vibration motor

722 which vibrates the buffer funnel 721 and its contents; an expansion joint 722; and a valve 723 in an outlet opening 724, which regulates the flow of drilling cuttings from the funnel 721 to the storage tank system 740. The transport device 700 is used, for example, to transport drilling cuttings from vibration screening devices to storage tanks, and in one particular aspect, the pressure tank 740 has a storage capacity of only approx. 0.3 cubic meters.

The pressure tank portion 740 may be like the pressure tanks of Figures IA, 3B-D, 7A and 8A. The pressure tank part 740 includes the small pressure tank 742 which receives cuttings through an inlet 743. A vent valve 744 will selectively vent the small pressure tank 742 and a relief valve 475 will selectively depressurize the small pressure tank 742 at a preset level. A conveyor 750 transports cuttings from the small pressure tank 742 to a discharge box 751, and the cuttings flows out a discharge end 752 of a pipe 753 to flow into a channel (not shown; for example, as channel 632, Figure 8A). A motor/gear system 760 rotates the conveyor 750.

Compressed gas from a source 770 is delivered in a line 771 to an inlet 772 on the outlet box 753; in a line 773 to an inlet 774 on the outlet end 752 of the outlet box 753; in a line 775 to an inlet 776 on the outlet box 751; and in a line 777 to an inlet 778 on the small pressure tank 742. The inlet 778 can have a very small diameter, as this should only equalize the pressure in the small pressure tank 742 with the pressure in the box 751 or in the outlet end 752. Each of the lines has a non-return valve 779. The funnel 721 can optionally be placed on insulation mounts or vibration-resistant mounts 782.

All the operating components in the transport device 700 are in connection (see dashed line) with a control unit 701 (for example as the control unit 680, figure 8A).

Each of the lines 771, 773, 777 has an on-off valve for flow regulation, respectively 771a, 773a, 777a (for example similar to valves 692); a pressure regulator, respectively 771b, 773b, 777b (similar to pressure units 690; the pressure is set manually or with the help of the control system, as the setting pressure in reality determines the highest working pressure in the system, for example two bar for dry cuttings or four bar for wet cuttings from the vibrating sight devices); and flow control valves, respectively 771c, 773c, 777c, which regulate the rate of pressure change (can be, for example, needle valves, throttle discs or similar devices).

Via line 777, gas is fed to the small pressure tank 742 at a pressure equal to the pressure in the gas that is fed to the outlet box 753 in line 771, and in the gas that is fed to the outlet box 751 in line 773, so that the pressure drop across the conveyor (feed screw) 750 will be minimal. The feed rate for drilling cuttings from system 700 is therefore determined by conveyor 750's rotational speed. In one aspect, gas is introduced downstream of a discharge valve 752a in line 773. With the discharge valve 752a closed, the small pressure tank 742 can be vented to the atmosphere, allowing the small pressure tank 742 to be refilled while cuttings are transported downstream of the discharge end 752.

The control system shown in Figures 9A to 9C can be used for any feeding device or storage tank described in this document.

Figure 10 shows a system 800 according to the present invention, with a drilling cuttings dryer 801 that dries drilling cuttings, for example a vortex dryer or a drilling cuttings dryer of the type described in GB-A-2 297 702. The vortex dryer 801 can be placed and fed immediately below the discharge end of a vibrating screening apparatus (not shown) or at the end of a chute (not shown) fed by a plurality of vibrating screening devices (not shown). The cuttings to be dried are, however, dried in the cuttings dryer 801 for a specific time or within a limited time interval. If the drilling cuttings are very wet, for example because the vibration screening devices have been exposed to "boundary particle clogging", where a large amount of drilling fluid will wash over the vibration screening device and into the cuttings dryer together with the cuttings, all or parts of the drilling cuttings will not be dry enough for transport with the pressure tank, or it will require further drying, further processing or storage and transport in or from a special storage tank. Thus, a transport system 802 with rotary drills 803, 804, which is driven by means of a motor/gear system 805, will selectively deliver drilling cuttings to a storage tank 810 or to a pressurized feeding device 820, on the basis of measurements carried out using a moisture sensor 821 (or sensors). Non-wet cuttings go to the pressurized feeder 820; if "wet" cuttings are detected, the drills will be reversed and the cuttings will be taken to storage tank 810 (which may be similar to storage tank 1). A sensor (or sensors) 821 reads the moisture content in the drill cuttings. If the sensor 821 reads "wet" cuttings (for example with a moisture content of one, three or five percent), the rotary drill is reversed and the cuttings are fed to the storage tank 810 for "wet" cuttings; and if

the cuttings is dry (for example, less than five percent moisture or oil content), the rotary drill is set in forward motion and the cuttings are delivered to the pressurized feed device 820, which blows the cuttings to box 825 pre-dry cuttings, which may be equal to the cuttings storage tank 1. In one particular arrangement, the cuttings will after it has been transported to the storage tank 810, could be transported to the box 825 for dry cuttings. Optionally, the sensor 821 may have a protective shield 821a for components outside a funnel and a protective shield 821b for components 821c inside a funnel (which applies to any humidity sensor or sensing device in any system described herein). Such a screen 821b protects sensor components

821c against drilling cuttings falling down a funnel. Multiple sensors 821 placed at intervals around the funnel 822 may be used (which applies to any system according to the present invention with sensor devices). In some aspects, such sensors are effective with a cuttings quantity that is at least 2.5 cm (one inch) thick and has an area of at least 20 to 26 square centimeters (three to four square inches). Such sensors can provide continuous readings for a more accurate application in a control system 829 that controls communication with components of the system 800, as indicated by dashed lines.

The control system 829 can switch the cuttings flow from system 825 (for example for sufficiently dry cuttings) and to system 810 (for example for relatively wet cuttings). In any system described herein, a first storage device or a "dry" storage device may be a storage tank, the hold of a ship, or a hold or reservoir on board a platform or in one or more platform legs. Such a storage device can, regardless of its shape and according to the present invention, have an overpressure system and a bottom supply system for air, so that the drilling cuttings material can be supplied with air from below (for example through a perforated bottom plate or element), which gives a material in a diluted phase, which is easier to transport. In one particular aspect, the humidity sensors are models MCT 300, MCT 600 and MCT 101-T from Process Sensors Corporation, Milford, Massachusetts, USA. As with any pressurized tank in any system herein, a cuttings tank 820a in system 800 may have a volume of between 0.05 m<3> and 0.2 m<3>. Figure 11 shows a system 830 according to the present invention, where a conveyor 831 driven by means of a motor/gear system 832 feeds drilling cuttings into two vortex dryers 833. Drilling cuttings that are processed in the vortex dryers 833 are fed into a hopper 835 in a feeding system 836 (similar to system 820, Figure 10) by means of a transport system 834. One of the vortex dryers 833 has a sieve which is stopped if the cuttings particles have a "limit size" ("limit size" means that the cuttings particles produced during drilling have a size distribution equal to the size distribution of the mesh openings of the sieves in the vibrating sieve apparatus; boundary grains can get stuck in the sieve openings and stop the sieve), and then wet drilling cuttings will flow out of the vortex dryer. A sensor 831 notices this, and it sends a signal to the second vortex dryer, which is then switched on, and which has a screen with a different mesh size than the first vortex dryer and can thus handle this particle size. The system 836 produces treated drilling cuttings which flows out into a channel 837. Figure 12 shows a system 850 according to the present invention, corresponding to the system in Figure 11, with a transport system 851 driven by means of a motor/gear system 852, which transports cuttings from vibration screening devices, hydrocyclones and/or centrifuges to a vortex dryer 853 which in turn delivers dried cuttings to a feeding device 856 (similar to the feeding device 836) via a chute 845, where the feeding device feeds the cuttings into an outlet channel 857. Beneath the vortex dryers 853 are hoppers 854 which feeds the feeding device 856. Figure 13 shows a system 900 according to the present invention for a drilling platform R, where the drilling cuttings (for example from vibration screening devices, centrifuges) flows to a feeding device 906 (similar to feeding device 820, 836, 856) with a vortex drying 907. The feeding device 906 processes the drill cuttings and feeds it into a storage tank (which can be of the type that is v ist on Figure IA, 1C or 7A). If the reading from the moisture sensor in the feeding device 906 shows that the drill cuttings are dry, a control unit (not shown) sends the flow of drilling cuttings from the feeding device 906 either to the internal bulk storage 910 in the platform R, or to an internal hold 911 in the supply ship B (if a supply ship is available). If the reading from the moisture sensor shows that the cuttings are wet, the control unit sends the flow of cuttings to storage tank 1 for wet cuttings on platform R or on board ship B. The bulk storage units built into platform R and the internal hold of supply ship B can handle dry bulk material, but not wet bulk material. By assessing how dry the cuttings are, it is therefore possible to send the cuttings to storage in the internal bulk storage units 910 built into the platform R, or in the internal hold 911 in the supply vessel B. The wet cuttings can be filled and stored in a storage tank of the type shown in Figure 1, or reprocessed in a cuttings dryer such as a vortex dryer or a cuttings dryer of the type described in WO 2004/000762 and GB-A-2 297 702, and then the moisture is measured on new. Figure 14 shows a system 920 according to the present invention, where vibrating screening devices 921 feed cuttings material onto a screw conveyor or conveyor belt 922, which leads the material to a vortex dryer 923 which delivers dried material to a pressurized screw feed device 924 (similar to the feed screw device shown in figures 8A, 9A and 10 to 12). Material processed through the pressurized feed screw device 924 flows out and is carried on in line 925. Fluid recovered from the vortex dryer 923 flows in a line 926 to a storage tank 927, from where it is pumped by a pump 928 to a centrifuge 930 via a line 929. Solids from the centrifuge 930 are carried away in a line 931 for disposal, and liquid is pumped into a line 932 to a storage tank 933. A pump 934 pumps liquid from

the storage tank 933, either in a line 939 to a sludge return system 935 (with a valve 936 closed and a valve 938 open); or back to the vortex dryer 923 in a line 937 (with valve 936 open and valve 938 closed).

Figure 15 shows a preferred embodiment 950 of the system according to the present invention, where a pressurized feed screw device 952 selectively feeds drilling cuttings material to a storage tank 953 dried drilling cuttings material or to a "wet" storage tank 954. A moisture meter 955 located in the funnel 968, reads the moisture content of the cuttings material, and control unit 960, which is connected to the moisture meter 955, controls a diverter valve 956 in such a way that a sufficiently dry cuttings goes to the storage tank 953 with flow to the "wet" tank system 954 closed; and wet cuttings go to the "wet" tank system 954 with flow to the storage tank 953 closed. Optionally, each storage tank 953 can have its own associated diverter valve 957, so that the flow to each box is selectively controlled using the control unit 960.

In some aspects, the pressurized feed screw device 952 is similar to the device of Figure 8A; the wet storage tank 954 is similar to the wet storage tank of Figure 10; and the storage tanks 953 are similar to the storage tanks of Figures 1B, 3B and 10. The control unit 960 controls the motors of each of the conveyors in the system 950.

In each of the systems in figures 10 to 15, there is an appropriate control system that controls the various components and is connected to the humidity sensors, valves, conveyors and motors.

Claims (38)

1. System for transporting cuttings from cuttings processing equipment to a storage tank (500), the system comprising a small pressure tank (472) and at least one storage tank (500), the small pressure tank containing cuttings material and gas under positive pressure, a source of pressurized gas ( 611), an inlet (616) for pressurized gas to apply pressurized gas to the cuttings material, the small pressure tank (472) having a first opening (743) through which cuttings material can be fed into the small pressure tank (472), and a second opening (752) through which cuttings material can flow out of the small pressure tank (472) and into a positive compressed air transport channel (837) for transporting the cuttings material to said at least one storage tank (500), said at least one storage tank (500) comprising a pressure tank (2) that accommodates drilling cuttings material and gas under positive pressure, a pressurized gas inlet (5) to the storage tank to apply pressurized gas to the drilling cuttings material, the pressure tank (2) having a first storage tank opening (7) where nom drilling cuttings material can be fed into the pressure tank (2) and a second storage tank opening (9) through which drilling cuttings material can pass out of the pressure tank (2), characterized in that the system further comprises a twist drill (750) which is inside the small pressure tank (472) and which is movable in the vicinity of the second opening (752), the small pressure tank (472) further comprising two sides (475) which slope towards each other to facilitate passage of the drill cuttings material which is exposed to pressurized gas through the second opening (752) into said positive compressed air transport channel (837) and a mechanical movement device (21, 26) in the storage tank, the storage tank movement device comprising a movement element (21) in the storage tank and a storage tank twist drill (11) inside the pressure tank (2), where the twist drill can be moved close to the second storage tank opening (9) to make it easier for the drill cuttings exposed to pressurized gas to flow through the second storage tank opening (9). 2. System according to claim 1, where it further comprises a box (18) for receiving the cuttings material flowing through the second storage tank opening (9), the box having a cuttings outlet (20) for connection to a further air pressure transport channel (63) with positive Print. 3. System according to claim 2, where it further comprises a conveyor compressed gas inlet (19) where compressed gas is used against the cuttings to facilitate the movement of the cuttings through said cuttings outlet (20). 4. System according to claim 3, where the storage tank pressure gas inlet (5) is located in the pressure tank (2) to allow gas under positive pressure to flow therein to prevent drilling cuttings from being blown back into the pressure tank (2) from the casing (18) below outflow. 5. System according to any of the preceding claims, wherein the small pressure tank (472) and the pressure tank (2) have undergone pressure testing to withstand a working pressure of at least two bar positive pressure. 6. System according to any one of claims 1-4, wherein the small pressure tank (472) and the pressure tank (2) have undergone pressure testing to withstand a working pressure of at least four bar positive pressure. 7. System according to any one of claims 1-4, wherein the small pressure tank (472) and the pressure tank (2) have undergone pressure testing to withstand a working pressure of at least seven bar positive pressure. 8. System according to any one of the preceding claims, wherein the second storage tank opening (9) has a length, and the movement element (21) comprises an elongated element (22) of essentially the same length as or greater length than the length of the other opening (9). 9. System according to claim 8, where said elongated element (22) has an edge which is shaped so that it facilitates the movement of drill cuttings towards the second opening. 10. System according to any one of the preceding claims, where the second storage tank opening (9) has a width, and the movement element (21) can be moved back and forth over said width. 11. System according to any one of the preceding claims, where the movement element (21) comprises a frame (21) with a control shaft (25) which is connected to at least one curved outer edge part (22). 12. System according to any one of the preceding claims, where the movement element (21) comprises a frame (22) with an essentially eye-shaped outer edge portion. 13. System according to any one of the preceding claims, where said storage tank twist drill (11) is placed under said second opening (9). 14. System according to claim 13, where said storage tank's twist drill (11) is placed in a chute (10). 15. System according to any one of the preceding claims, further comprising a motor for rotating said storage tank twist drill (11). 16. System according to any one of the preceding claims, further comprising a motor for rotating said twist drill (750). 17. System according to any one of the preceding claims, further comprising fingers (17) located at the end of the storage tank twist drill (11) to facilitate the release of said drill cuttings from said storage tank twist drill (11). 18. System according to any one of the preceding claims, wherein said storage tank twist drill (11) comprises at least one blade (14) with constant pitch or variable pitch. 19. System according to any one of the preceding claims, wherein it further comprises an air valve (8a) to prevent the storage tank (2) from being over-pressurized. 20. System according to any one of the preceding claims, where it further comprises a cover (532) for selectively covering said second storage tank opening (9). 21. System according to any one of the preceding claims, where the storage tank (2) essentially has a flat inner bottom (3). 22. System according to any one of the preceding claims, wherein said storage tank (2) has a substantially vertical wall. 23. System according to any one of the preceding claims, wherein said storage tank (2) has a domed top (4). 24. System according to any one of the preceding claims, wherein the storage tank (2) has a generally cylindrical shape with a generally circular bottom (3), wherein the second storage tank opening (9) passes through the generally circular bottom (3) . 25. System according to any one of the preceding claims, wherein said first opening (743) of the small pressure tank (500) contains a valve (478) for regulating the cuttings inflow. 26. System according to any one of the preceding claims, wherein said first storage tank opening (7) has a non-return valve (8) which prevents drilling cuttings from flowing out through the first storage tank opening (7). 27. System according to any one of the preceding claims, wherein said small pressure tank (472) has a capacity of between 0.15 cubic meters and one cubic meter. 28. System according to any one of the preceding claims, where said storage tank (2) has a capacity of at least three cubic metres. 29. System according to any one of the preceding claims, where it further comprises a moisture sensor (821, 831, 955) which reads the moisture content of drilling cuttings. 30. System according to claim 29, where it further comprises a funnel (835), and where said humidity sensor (821, 831, 955) is placed in said funnel (835). 31. System according to claim 29, where said humidity sensor is placed inside the small pressure tank. 32. System according to claim 29, 30 or 31, where it further comprises a control unit (701) which collects data from said humidity sensor (821, 831, 955), and a device (802, 805, 956, 957) which diverts the drill cuttings as a reaction to the data. 33. System according to claim 32, where said device (956, 957) comprises one or both of: a diverter valve (956, 957) which diverts said drill cuttings; a screw conveyor (802). 34. System according to any one of claims 29 to 33, wherein said at least one storage tank (500) is for storing wet drilling cuttings, the system further comprising a further storage tank (800) for storing dry drilling cuttings. 35. System according to any of the preceding claims, wherein said storage tank for storing dry cuttings is an internal bulk storage in a drilling platform or the internal hold of a ship or barge. 36. System according to claim 1, where it further comprises a box (624) for receiving the cuttings material that flows through the small pressure tank's (622) second opening, the box having a cuttings outlet for connection to said air pressure transport channel (632) with positive pressure . 37. System according to claim 36, where it further comprises a conveyor compressed gas inlet (627) where pressurized gas is used against the cuttings to facilitate the movement of the cuttings through said cuttings outlet. 38. System according to claim 37, wherein the storage tank pressure gas inlet (616) is located in the small pressure tank (622) to allow gas under positive pressure to flow therein to prevent cuttings from being blown back into the small pressure tank (622) from the case (624) during outflow.