FIELD OF THE INVENTION

The present invention in general, relates to a method and device for discharging particulate material generated, particularly during offshore exploration and production operations.

Particularly, the present invention relates to a method and device for discharging particulate material more efficiently and rapidly, for their final disposal so that drilling waste management can be done in a technically perfect manner. More particularly, the present invention relates to a method for discharging particulate material generated from exploration and production operations according to the preamble of claim 1 and to a device according to the preamble of claim 9.

TECHNICAL BACKGROUND OF THE INVENTION

It is known that during on/off shore drilling operations, drill wastes such as drill cuttings, chemicals, metallic wear materials, petroleum residuals and the like are generated. All these are generally particulate material, sometimes paste-like, heavy and sticky.

With intensification of mandatory environmental regulations for disposal of such drill cuttings and the like, (hereinafter all such material is referred to as drill cuttings/particulate material for the sake of brevity) particularly in on/off-shore environments, need for efficient disposal of these drill cuttings have cropped up.

It is known that traditionally such drill cuttings were disposed by filling up boxes or skips on the rig and thereafter crane lifting and dropping on boats for transportation, treatment and final disposal. However, crane lifting and filling up of boxes are not only expensive, but also this technology is not perfect in respect of health, safety and environment risks.

More particularly, crane operation is almost impossible in the high seas and during hostile weather, leading to halting of removal of such waste. Crane operations of boxes or skips are also prone to spillage of particulate material, in the marine environment. Incomplete removal of drill cuttings and incidents of spillage, disturb the health of workers involved on the rig and pollute the marine environment. Large number of boxes also cause occupying of valuable deck space needed for other deck cargo.

The above disadvantages, led to the development of new technologies for disposal of drill cuttings. For example, International PCT published specification numbered WO 00/76889, discloses a method of conveying a non-free flowing paste comprising loading the paste into a container and applying a compressed gas to the container, to cause the material to flow out of the container into storage assembly, located on a transport vessel. However, this document does not teach how to get rid of bridge created when only material in the center move out and leave material near the vessel wall or plug that generates inside the vessel completely blocking the outlet, on application of compressed gas to the particulate material, temporarily stored within the vessel.

Attempts have been made to solve the problem narrated in the preceding paragraph, by applying tanks which are subjected to vibration, once formation of such bridges or plugs are developed in the drill cuttings, within the tanks. This technology is not full proof in respect of complete removal of such plugs which in turn leads to inefficient removal of particulate material into the storage tanks on transporting vessels. Hence, this technology involves increased productive time as well. The same is true for another known technology, which applies a cylindrical tank with a rotating knife arrangement, that discharge into an auger. This technology also face acute plugging problem.

In general, prior art has no teaching on substantial prevention of plugging of particulate material, within the temporary storage unit, during application of compressed air. No teaching is also there to simultaneously ensure efficient evacuation of particulate material into the units on transportation vessels, for final disposal of these drill wastes. The present invention provides a methodology and a device that specifically solves the two problems as mentioned in the preceding paragraph. Precisely, the bridging and plugging problem is substantially sorted out and simultaneously, efficient discharge of particulate material into storage tanks on the transport vessel is also ensured.

OBJECTS OF THE INVENTION

It is the prime object of the present invention to provide a method and a device for efficient discharging of particulate material generated from exploration and production operations, which substantially nullify bridging and plugging of materials and ensures efficient discharge of particulate material into storage tanks on the transport vessel. It is another object of the present invention to provide a method and a device for efficient discharging of particulate material generated from exploration and production operations which is not only rapid and cost effective, but also simultaneously efficient. It is yet another object of the present invention to provide a method and device for discharging particulate material more efficiently and rapidly, such that drilling waste management can be done in a technically perfect manner complying with environmental regulations. It is a further object of the present invention to provide a device for discharging particulate material which has a simple construction, occupies substantially low deck space and is easy to replace, install and uninstall. All through the specification including the claims, the words "vessel", "tank/container", "particulate material/drill cuttings", "evacuation tank/blower", "storage tank", "valve", "frame", "vibrations/micro-vibrations", "dampers", "flat/cylindrical", "conical hopper" are to be interpreted in the broadest sense of the respective terms and includes all similar items/devices/methods in the field known by other terms, as may be clear to persons skilled in the art.

Restriction/limitation, if any, referred to in the specification, is solely by way of example and understanding the present invention.

SUMMARY OF THE INVENTION According to one aspect of the present invention, it provides a method for discharging particulate material generated during exploration and production operations. The method comprises allowing particulate material to enter at least one container having a storage tank with a top portion and a bottom portion. A control valve at the bottom portion of the tank is kept closed during such inflow of particulate material into the tank. In the event of opening the control valve for allowing particulate material to get discharged from the tank into an evacuation unit, operatively connected to the lower portion of the valve, the tank is simultaneously vibrated by means of vibration means such as motors. These motors are connected directly to the tank and due to such vibrations; the particulate material is discharged freely from the lower portion of the tank into the evacuation unit. The evacuation of material from the evacuation unit to a transportation vessel is enhanced by airflow in a cyclone motion, created by the evacuation unit due to its configuration. Preferably, particulate material is allowed to enter the container by means of inlet pipes and during such filling of material, excess air is vented out through an air outlet bend that runs into an air outlet vent and the inlet pipes are closed during passage of particulate material into the evacuation unit . More preferably, the air outlet vent is closed during material inflow from the tank, into the evacuation unit and air is blown through the inlet pipe lines and the vibrations created in the tank are prevented from being transferred to the frame and thus to the base by dampers, which are suitably located so as to suspend the upper portion and the lower portion of the tank, on a frame structure.

Even more preferably, the evacuation unit is a pneumatic blower, which creates a predetermined recoil pressure inside the tank for removing all left over material along the walls of the tank, once the discharging of material from the tank into the blower is over and the control valve is open.

Most preferably, when the pneumatic blower is full, the control valve is closed and the vibration motors are stopped and air pressure is increased by compressing air inside the blower via its air inlet pipe by opening an air inlet valve and when sufficient working discharge pressure is achieved the material and air are discharged out of the blower via its material outlet pipe by opening a material outlet valve , for feeding into storage tanks on a transportation vessel.

To enhance the process of feeding particulate material to the storage tanks on the transportation vessel, as soon as the pneumatic blower is empty the material outlet valve is closed and air is compressed continuously via the material outlet pipe, until the material reach the transportation vessel.

Immediately as the material outlet valve is closed, the next filling cycle is started by opening the valve to refill the pneumatic blower from the lower portion of the tank and the same steps of filling and discharging are repeated.

Another aspect of the present invention provides a device for discharging particulate material generated during exploration and production operations. It comprises a container having a storage tank with a top portion and a bottom portion, the bottom portion has a control valve for stopping or discharging of material from the bottom portion of the tank. Vibration means such as motors are connected directly to the tank for vibrating the tank during discharging material from the bottom portion of the tank into an evacuation unit operatively connected to the lower portion of the control valve. The evacuation unit has a configuration such that during evacuation of material through it to a transportation vessel, cyclone motion can be effected.

BRIEF DESCRIPTION OF THE DRAWINGS

Having described the main features of the invention above, a more detailed and non-limiting description of a preferred embodiment, with reference to the drawings is provided below.

Figure 1 is a front view of the device according to the preferred embodiment of the present invention described.

Figure 2 is an exploded front view of the preferred embodiment shown in figure 1 without the frame structure and without the inlet and outlet pipes for the sake of clear understanding.

DETAILED DESCRIPTION OF THE INVENTION

The following describes the preferred embodiment of the present invention illustrated in figures 1 and 2, which is purely exemplary for the sake of understanding the invention and non-limiting.

In all the figures, like reference numerals represent like features. Further, when in the following it is referred to "top", "bottom", "upward", "downward", "above" or "below", "right hand side " or "left hand side" , "upper portion", "lower portion" and similar terms, this is strictly referring to an orientation with reference to the sea bed, where the sea bed is considered to be horizontal and at the bottom.

It should also be understood that the orientation of the various components and their numbers might be otherwise than shown in the drawings, without deviating from the principle of the invention.

Figure 1 illustrates a schematic front view of the device A. It comprises of a storage tank, for temporarily storing particulate material. The upper portion of this tank is a cylindrical bulk tank 16a, while the lower portion is conical 16b.

The lower end of the conical portion 16b of the tank has an extension joint 7. The latter at its lower end has a control valve 8, which connects at its bottom portion with a pneumatic blower 10.

The tank in its entirety and the other features (hereinafter sometimes referred together as tank unit or device) as described in the two preceding paragraphs are made in one piece and all these are suspended on frame 14, by means of dampers 5. In the embodiment shown in figure 1 , the dampers 5 are located close to the middle portion of the cylindrical portion 16a and close to the lower portion of the cone 16b so that the entire tank unit is perfectly suspended on the frame 14. However, it should be understood that the positions of these dampers may vary, depending upon the structure of the frame 14 and the tank unit and all these fall within the scope of the present invention.

Since, the entire device is made in one piece; it occupies minimum base area on the rig/ship. This aspect also ensures that the device is easy to carry, replace, install and uninstall. The equipment is built on shore and is transported out to the rigs or ships by supply vessels.

These dampers 5 are actually vibration dampers as it would be clear from the functioning of the device, as explained later. Vibration means such as motors 6 are provided at the two sides of the conical portion 16b at its lower end. These are essentially in direct contact with the tank and can be located in other positions as well. The motors 6 are adjustable, in respect of frequency and amplitude. The functions of these motors 6 have been explained later.

Pipe inlet 1 enter into the top portion of the cylindrical part 16a by means of an inlet bend 2. These bring particulate material into the tank. The air outlet bent 3 originating from the top portion of the tank, connects to an air outlet vent 4. These release the excess air during filling up of the tank with particulate material. Detailed functions of all these have been explained later.

From figure 1 it would be clear that the inlet pipes 1 , 2 and the air outlet vents 3, 4 are placed on opposing sides of the cylindrical portion 16a, at its top portion along both sides of the frame 14. This is done to prevent entrainment of particles of drill cuttings, into the air vent 4.

The tank unit along with the frame 14 is placed on the rig/ship, for temporary storage and then for transportation of particulate material/drill cuttings, for its final disposal. The frame 14 is locked at its four corners, with suitable locks 15.

For transportation of material from the blower 10 to a storage tank/container (not shown) on a transport vessel (not shown), the blower 10 has a suitable configuration. This configuration enhances the transportation of material by generating cyclone motion. This configuration would be clear from figures 1 and 2. Referring again to figure 1 , the blower 10 has a conical cross-section.

At one side of the blower 10, there is an air inlet pipe 12, through which compressed air is thrust inside the blower 10. The air inlet valve 9 controls opening and closing of the air inlet pipe 12. On the other side of the blower 10 there is material outlet pipe 13, opening and closing of which is controlled by the material outlet valve 1 1 . Further, there is a bypass line (17) and corresponding bypass valve (17) provided between the air inlet tube (12) and the material outlet pipe (13), whose functions will be described more detailed later.

Figure 2 is an exploded view of the tank unit in its entirety. The inlet and outlet pipes and the frame 14 are not shown for better understanding. Figure 2 clearly illustrates the structure of the tank unit, as explained with reference to figure 1 hereinbefore. The top portion 16a of the tank is cylindrical and the lower portion is a conical chute 16b. Top end of the expansion joint 7 is connected to the lower end of the cone 16b while its lower end is connected to the control valve 8, the latter at its bottom end being connected to the top end of the blower 10. The position of the vibration dampers 5 and the vibration motors 6 are also clear. Since the vibration motors 6 are in contact with the tank so the vibration produced is more efficiently conveyed into the tank unit.

Figure 2 also makes it clear that the device with all connections at the bottom are made in one piece and hence occupies minimum base space on the rig or on the ship. That apart, figure 2 makes it clear that the device A (see Fig. 1 ), can be easily carried, replaced, installed and uninstalled for its being in one piece as explained before. The control valve 8 in figure 2 is shown as a dome valve. However, the invention is not restricted to this and it may be knife valve as well or any other type of valve as known to persons skilled in the art.

Referring again to figure 1 drill cuttings (drilling mud and/or drilling fluid)/ particulate material from a preceding sieving and cleaning step, is fed to the top portion of the cylindrical unit 16a by means of the inlet pipe 1. The purpose of the tank 16a, 16b, which is usually placed on a drilling installation rig/drilling ship or FPSO, is to store the drill cuttings for further transport to other containers e.g. on board a supply vessel or other ship for transport to shore. Since the device most often, but not necessarily, is placed on a drilling rig the whole device is placed in a frame 14 in order to hoist the whole device onto or from a deck. The compact embodiment is to achieve as little "footprint" as possible on the deck, due to space limitations. In the shown embodiment, the inlet tube 1 goes from the bottom of the device to the top of the closed bulk tank 16, but this arrangement is a secondary feature in order to get all the inlets and outlets in the bottom of the whole structure when used as on a drilling rig/drilling ship and so on. Now the entire functioning is explained sequentially with reference to the figures 1 and 2. As stated before, the sieved and cleared material is transported into the tank via the material inlet pipe 1 through the material inlet bend 2 and into the tank. The transportation air is ventilated out via the material outlet bend 3 and further through the material outlet pipe 4. The material is then temporary stored in the tank, keeping the control valve 8 closed, until a typical transportation vessel arrives on location.

Once a transportation vessel arrives, the material is first moved down into the pneumatic blower 10. This process is enabled as the control valve 8 is opened between the conical hopper 16b and the pneumatic blower 10. Immediately and simultaneously, the vibration motors 6 start and create vibrations into the tank 16a, 16b. This is possible as the tank is suspended in the tank frame 14 via the vibration dampers 5. The material is vibrated free from the tank wall (both from the walls of the cylindrical tank 16a and the conical hopper 16b) and with help from gravity and moves through the valve 8 and into the pneumatic blower 10. Hence, this get rids substantially of the formation of bridge/plugs within the tank. This aspect of making the temporary storage tank dynamic simultaneously, with emptying of material from the tank is unique. The vibration motors 6 being in contact with the tank, particularly with the lower portion of the tank, facilitates this unique aspect.

The vibration dampers 5 ensure that the vibrations created in the tank are prevented from being transferred to the frame 14 and thus to the deck. This is also facilitated by the expansion joint 7 at the lower end of the conical chute 16b. Rubber or other resilient material are incorporated within these features to prevent the vibration to enter valve 8 and pneumatic blower 10 below.

The material movement from bulk tank 16 to pneumatic blower 10 is preferably assisted by closing the vent air outlet pipe 4 and blowing air through the material inlet pipe 1 , while the control valve 8 is open and the micro vibrations created by the motors 6 are on. Another unique aspect is that the pneumatic blower 10 creates an assisting recoil pressure to create a particle lift off pressure/movement to help release the material from the walls of the cylindrical portion 16a and also from the walls of the conical hopper 16b. This is achieved by continuing to blow air into the pneumatic blower 10 through the air inlet 12 by opening the air inlet valve 9, after the material has been discharged into the blower 10 from the tank and material outlet valve 1 1 has been closed. The recoil pressure is monitored, varied and controlled depending on effect required. When the pneumatic blower 10 is full, the control valve 8 is closed, vibration motors 6 are stopped and compressed air pumped in via the air inlet pipe 12 by opening the air inlet valve 9. When sufficient working discharge pressure is achieved the material and air is discharged out via the material outlet pipe 13 by opening the material outlet valve 1 1 . The material evacuation happens in a cyclone motion due to the inside configuration of the pneumatic blower 10. All these constitute another unique aspect of the present invention.

As soon as the pneumatic blower 10 is empty, the material outlet valve 1 1 is closed and the compressor(not shown) continues feeding air via the air inlet pipe 12, then via bypass valve (18) and a bypass pipe (17) to outlet pipe 13 (not shown) and then through the material outlet pipe 13, until the material reach the transportation vessel. The material outlet pipe 13 is so configured such that, even if the material outlet valve 1 1 is closed, it will continue to allow passage of air through the bypass pipe.

Immediately as the material outlet valve 1 1 is closed the next filling cycle start by opening valve 8 to refill the pneumatic blower 10 from the vibrating tank 16a, 16b and the process is repeated as before.

From the description hereinbefore it would be clear to persons skilled in the art that all objectives of the invention have been achieved. Further, only one device A has been illustrated and described. In reality, there can be many such devices all functioning in the same way and the present invention embraces such arrangement as well.

The present invention has been described with reference to a preferred embodiment and some drawings for the sake of understanding only and it should be clear to persons skilled in the art that the present invention includes all legitimate modifications within the ambit of what has been described hereinbefore and claimed in the appended claims.

The device according to present invention can also be used as temporary storage for other processes as mechanical dryers, pelletizers and thermal dryers of the material on/off location.