Abstract:
A method of, and apparatus for, transferring material, which may be hydrocarbon exploration and production industry by-products in the form of drill cuttings, from a first location to a second location. A container is provided containing fluid and the material is transferred from a first location outside of the container to a second location inside the container. Fluid, which is typically air, is at least partially evacuated from within the container in order to facilitate progression of the material into the container.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a national stage filing under 35 USC §§ 365 &amp; 371 of International Application No. PCT/GB2005/001606, filed Apr. 27, 2005, which claims priority under the Paris Convention to United Kingdom Application No. GB 0409318.3, filed Apr. 27, 2004. The entire disclosures of these prior applications are incorporated herein by this reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to apparatus and a method for transporting material, and particularly but not exclusively relates to apparatus and a method for transporting non free flowing or relatively sticky paste-like materials such as those produced by hydrocarbon exploration and production operations. 
         [0003]    In the hydrocarbon exploration and production industry it is often necessary to transfer large quantities of material from, for example, a drill rig to a transport vessel in order that the material can then be transported to an on-shore location for further processing/disposal. The materials used in/created by drilling operations such as drill cuttings, pastes or sludge are often highly viscous substances which are therefore difficult to transport due to their cohesive properties. One way of transporting such materials is to empty them into a container or skip and then transport the container or skip onto a vessel; however maneuvering the container or skip around the rig, as required in such a method, presents a number of dangers to personnel operating on the rig. 
         [0004]    In order to transfer drill cuttings from the rig to the vessel more safely it is known to transfer the drill cuttings firstly to a number of large holding tanks. When the holding tanks are full, they are connected via tubing to transport tanks on board a transport vessel and transferred thereto using compressed air or a similar propellant in order to assist progression of the material along the tubing; however such systems can become blocked due to the difficulty in obtaining a large enough pressure differential along the long distance of tubing between the rig and the vessel. The tendency for highly viscous materials to stick together rather than to flow, combined with the fact that the long tubing has a tendency to sag thereby creating certain areas along the pipe where the flow of the highly viscous materials must act against gravity, makes blockages along the pipe more likely. 
       SUMMARY 
       [0005]    According to one aspect of the present invention there is provided a method of transferring material from a first location to a second location comprising the steps of:
       providing a container containing fluid;   transferring material from a first location outside of the container to a second location inside the container; and   at least partially evacuating fluid from within the container in order to facilitate progression of the material into the container.       
 
         [0009]    Preferably, the transfer of material from the first location to the second location and evacuating the fluid from the container are performed substantially simultaneously. 
         [0010]    Preferably, the method further comprises the step of transferring the material along a first conduit under application of pressure upstream of the material, in order to progress the material from a first location outside of the container to a second location inside the container. 
         [0011]    Preferably, the method further comprises the step of at least partially evacuating the fluid, which is preferably gaseous and is more preferably air, from the container along a second conduit in order to substantially create a vacuum within the container. 
         [0012]    Preferably, the fluid is at least partially evacuated from the container whilst substantially avoiding removal of the material from the container. 
         [0013]    Preferably, the method further comprises the step of providing a second container, which is typically upstream of the first container, where the second upstream container typically provides a temporary storage facility for material to be transported. 
         [0014]    Typically, the method further comprises the step of providing a first pumping means for pumping material which may be from a source of material into the second container under pressure such that the material may be deposited in the second container prior to being transferred to the first container. More preferably, pressure is applied to the second container and the material therein when the second container contains a desired level of material. More preferably, the second container is then emptied by evacuating at least a portion of the material within the second container, typically along a discharge conduit, which action is preferably assisted by the pressure applied to the second container. 
         [0015]    Preferably, the discharge conduit is in fluid communication with the first conduit via an intermediate or transfer pumping and/or vacuum generation means in order to allow the material from the second container to be conveyed to the first container. 
         [0016]    Typically, the first container is located on a transportation means such as a sea going vessel and the second container is located proximal to the first pumping means and also is preferably located proximal to a supply of the material such as a primary drill cuttings source such as on a drilling rig. Preferably, the intermediate or transfer pumping and/or vacuum generation means is located proximal to and downstream of the second container. Typically, a transfer conduit connects the intermediate or transfer pumping and/or vacuum generation means to the first container. 
         [0017]    Preferably, the material comprises drill cuttings. 
         [0018]    According to another aspect of the present invention there is provided material transfer apparatus comprising:
       a container containing fluid;   material transfer means adapted to transfer material from a first location outside the container to a second location inside the container; and   material urging means adapted to facilitate transfer of the material from the first location to the second location by at least partially evacuating fluid from within the container.       
 
         [0022]    Preferably, the material transfer means comprises a first tubular conduit which passes through an inlet portion of the container and more preferably further comprises an intermediate or transfer pumping and/or vacuum generation means connected thereto. 
         [0023]    Preferably, the intermediate or transfer pumping and/or vacuum generation means comprises a pump and a vacuum device and is adapted to be selectively switched between the pumping and vacuum producing modes as desired. 
         [0024]    Preferably, the intermediate or transfer pumping and/or vacuum generation means also comprises an intermediate storage tank and is typically located upstream of the container. 
         [0025]    Preferably, the material urging means comprises a second tubular conduit which passes through an outlet portion of the container and more preferably further comprises vacuum generation means connected thereto. 
         [0026]    Preferably, the inlet and outlet portions are spaced apart across a diameter of the first container in order to prevent material exiting the inlet portion from entering the outlet portion. Optionally, a filter may also be provided on the outlet portion to further prevent the material from entering the outlet portion and hence the vacuum generation means. Typically, the inlet and outlet portions are located toward the upper end of the first container. 
         [0027]    Typically, the fluid is gaseous and preferably is air. 
         [0028]    Typically, the material is a highly viscous material which is typically drill cuttings or similar hydrocarbon exploration and production industry by-products. 
         [0029]    Embodiments of the invention have the advantage that they allow material to be pumped by the intermediate or transfer pumping and/or vacuum generation means along the first conduit until it is expelled into the container from the inlet portion on the first conduit. The progression of the material along the first conduit and into the container is eased and/or assisted by the simultaneous substantial vacuum provided across the diameter of the container as provided by the second conduit and the vacuum generation means. 
         [0030]    Preferably, the apparatus further comprises a second container which contains material which has preferably been pressurised and which is typically located upstream from the first container and which is further preferably located upstream from the intermediate or transfer pumping and/or vacuum generation means. Typically, the second container is connected to the first container such that material may be transferred therebetween. More preferably, the connection between the first and second containers passes through at least a portion of the intermediate or transfer pumping and/or vacuum generation means. 
         [0031]    This allows a small amount (limited by the maximum volume of the intermediate or transfer pumping and/or vacuum generation means) of material to be sucked by the vacuum of the intermediate or transfer pumping and/or vacuum generation means from the second container and into an intermediate storage tank of the intermediate or transfer pumping and/or vacuum generation means. The pressurised contents of the second container typically assist in this regard by providing a positive pressure differential from the inside of the second container to the outside. When the intermediate storage tank is full the intermediate or transfer pumping and/or vacuum generation means is then switched either manually or automatically to its pumping mode in order to pump the contents of the intermediate storage tank into the first container (which is assisted by the vacuum produced in the first container by the second conduit and vacuum generation means). 
         [0032]    Typically, the first and/or second containers are large, silo-type containers which are typically cylindrical in shape. Preferably, the or each container is provided with a plurality of circumferentially arranged material chutes, preferably having a multi-sided (which in preferred embodiments is hexagonal) cross section, adapted to substantially prevent the material within the or each container from becoming compacted such that the material will no longer flow. Preferably, a separation device, which is preferably a cone having a multisided (which in preferred embodiments is hexagonal) cross section, is provided adjacent the chutes in order to substantially prevent large lumps of material from settling within the chutes. Alternatively, a standard conically shaped silo chute may be provided on the or each container. 
         [0033]    These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  is a schematic diagram showing the flow of drill cuttings through apparatus in accordance with the present invention; 
           [0035]      FIG. 2A  is a schematic front view diagram of a tank used in the apparatus of  FIG. 1 ; 
           [0036]      FIG. 2B  is a plan view of the top of the tank of  FIG. 2A  looking in the direction indicated by the reference lines B-B; 
           [0037]      FIG. 2C  is a partial cross-sectional side elevation of the tank of  FIG. 2A ; 
           [0038]      FIG. 2D  is a cross-sectional view of the valve arrangement on the bottom of the tank of  FIG. 2A  taken through the line C-C; 
           [0039]      FIG. 2E  is a partial cross-sectional view of the tank of  FIG. 2C  looking in the direction indicated by reference line D; and 
           [0040]      FIG. 2F  is a cross-sectional view of the tank of  FIG. 2E  taken through the line E-E showing the hexagonal chute and cone arrangement used in conjunction with a preferred embodiment of the apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    It is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention. The embodiments are described merely as examples of useful applications of the principles of the invention, which is not limited to any specific details of these embodiments. 
         [0042]    In the following description of the representative embodiments of the invention, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. 
         [0043]    Referring to  FIG. 1 , drill cutting material transportation apparatus  10  is provided. The apparatus  10  has a first vacuum/pump unit  12  connected to a holding tank  14  by a holding tank input pipe  16 . The holding tank  14  is connected to a second vacuum/pump unit  18  by a holding tank output pipe  20 . The second vacuum/pump unit  18  also connects to a transportation tank  22  via a transfer pipe  24 . A vacuum pipe  26  connects to a third vacuum/pump unit  28  and is in fluid communication with the inside of the transportation tank  22 . 
         [0044]    The vacuum/pump units  12 ,  18 ,  28  can be selectively switched between a vacuum mode which sucks material into an integrated transfer tank  30  and a pumping mode which blows material out of the integrated transfer tank  30  under pressure. The pressure differential required for both the vacuum and pumping modes is provided by an air compressor (not shown) attached to or integrated with the units  12 ,  18 ,  28 . An example of a preferred unit  12 ,  18 ,  28  able to provide such pumping and vacuum capabilities is the SUPAVAC™ system distributed worldwide for the oil and gas industry by ITS Drilling Services Limited of Aberdeen, UK, but the skilled reader will realise that other conventional vacuum/pump units may also be suitable although such other conventional vacuum/pump units may not operate as quickly nor as efficiently. 
         [0045]    The holding tank  14  and transportation tank  22  are large cylindrical tanks  14 ,  22  which are able to hold a relatively large volume of material. Typically, the holding tank  14  and transportation tank  22  are each able to hold around 15 m 3  to 20 m 3  Of material, though it should be noted that smaller or larger tanks could be used without affecting the overall operation of the apparatus  10 . 
         [0046]    The holding tank  14  is provided with an external upright pipe  32  which extends from the bottom of the tank  14  to the roof of the tank  14  at which point it terminates with an aperture  34 , such that the interior of the external upright pipe  32  is in fluid communication with the interior of the holding tank  14 . The bottom of the external upright pipe  32  is connected to the first vacuum unit  12  by the holding tank input pipe  16 . Though the upright pipe  32  is provided externally in the apparatus  10  shown in the Figures, it should be appreciated that this upright pipe may alternatively be provided internally. 
         [0047]    The bottom of the holding tank  14  may simply have a standard flat or conically shaped exit chute connected to outlet valves; however in the present and preferred embodiment (as best seen in  FIGS. 2C ,  2 E and  2 F) a number of hexagonal chutes  36  are provided around the circumference of the tank  14  bottom in a honeycomb arrangement. A cone  40  having a hexagonal cross section is also provided in the centre of the circumferentially arranged hexagonal chutes  36 , the purpose of which will be described subsequently. A suitable honeycomb shaped insert  36  is described in PCT Application No WO 00/55073, the contents of which are incorporated herein by reference. 
         [0048]    The lowermost point of each chute  36  is provided with an outlet discharge valve  38  connected to discharge tubes  42  which converge onto the end of the holding tank output pipe  20 . 
         [0049]    A substantial number of components on the transportation tank  22  are substantially the same as the holding tank  14  and will therefore not be described further. In the following description, where this applies the same reference numeral has been used with an additional A being suffixed to the reference numeral. 
         [0050]    Unlike the holding tank  14 , the discharge tubes  42 A of the transportation tank  22  are not connected to an output pipe in the arrangement shown in  FIG. 1 . In addition however, a further external upright pipe  44  is provided for the tank  22  opposite the external inlet upright pipe  32 A. A vacuum pipe inlet aperture  46  is provided on the upper end of the additional external upright pipe  44 , the purpose of which will be described subsequently. The additional external upright pipe  44  extends downwardly from the vacuum pipe inlet aperture  46  and connects to the vacuum pipe  26  which leads on to the third vacuum unit  28 . 
         [0051]    It should be noted that the length of the pipes  16 ,  20 ,  24 ,  26  in  FIG. 1  are not to scale and have been altered for clarity. Indeed the transfer pipe  24  must be long enough to allow material to be transported from the vacuum unit  18  adjacent the holding tank  14  located on the rig (not shown) to the transportation tank located on the supply vessel (not shown) and this distance is likely to vary in length per application or project, typically from 10 m to 200 m in length. 
         [0052]    In the following description the flow of drill cuttings throughout the apparatus  10  is illustrated by dark shaded arrows  48  on  FIG. 1  and the negative suction (or vacuum) pressure differential created by the vacuum units  12 ,  18 ,  28  is illustrated by the unshaded arrows  50 . 
         [0053]    In operation, the vacuum mode of the first vacuum unit  12  is switched on. This creates a vacuum in the tank  30  which sucks drill cuttings  48  into the tank  30 . It should be noted that the drill cuttings  48  are initially output from a primary drill cutting treatment equipment such as shale shaker/centrifuge etc. such as those typically used in drilling operations. The vacuum in the transfer tank  30  is sustained until the transfer tank  30  is filled with drill cuttings  48  which typically occurs when around 400 litres are contained within the tank  30 . When full, the transfer tank  30  can no longer suck drill cuttings  48  and must now be emptied. 
         [0054]    In order to empty the tank  30 , the first vacuum unit  12  is switched to its pumping mode. In its pumping mode, compressed air is introduced into the tank  30  by the compressor (not shown). The increased pressure within the tank  30  expels the drill cuttings  48  within the tank  30  into the holding tank input pipe  16 . The drill cuttings  48  are progressed up the upright pipe  32  due to pressure of compressed air in the tank  30  acting upon them until they reach the internal inlet aperture  34 , at which point the drill cuttings  48  enter the holding tank  14 . Gravity causes the drill cuttings  48  to fall toward the bottom of the tank  14  and in so doing begins to fill the holding tank  14  from the bottom upwards. 
         [0055]    Once the first vacuum unit  12  has expelled the contents of its tank  30  into the holding tank  14 , it is then switched back to vacuum mode (either automatically or by a manual operator) in order to refill with drill cuttings  48  from the shale shaker/centrifuge, etc. on the rig platform (not shown). Once filled with the next load of drill cuttings  48  the first vacuum unit  12  empties its contents into the tank  14  in a similar fashion as previously described. This cyclical filling and emptying of the tank  30  is repeated by the first vacuum unit  12  until the holding tank  14  is filled to a desired level determined by the user. The weight, and hence volume, of material within the holding tank  14  can be calculated by the user by subtracting the known empty weight of the holding tank  14  from the total weight of the holding tank  14  in operation whilst taking into account the effect of the specific gravity of the material (when calculating the volume). 
         [0056]    It should be noted that the vacuum units  12 ,  18 ,  28  have very few moving parts e.g. impellers etc. since these could be easily clogged up by the highly viscous material passing through the units. Instead, the vacuum units  12 ,  18 ,  28  mainly comprise chambers and valves (not shown) which, in conjunction with the compressed air supply can be manipulated to provide the necessary vacuum or pumping action as required. 
         [0057]    Though a single holding tank  14  is shown in  FIG. 1 , in order to increase the capacity of the rig for retaining drill cuttings  48  before they must be offloaded, the rig may have a number of holding tanks  14 . A typical number of holding tanks on the rig would be between 1 and 8 though more could be provided if the rig structure permits. When a number of holding tanks  14  are provided, the input pipe  16  is simply detached when the holding tank  14  to which it is connected is full, and is then reconnected to an empty holding tank  14 . 
         [0058]    When it is desired to transfer the contents of the holding tank  14  to, for example, a sea going supply vessel (not shown), one end of the holding tank output pipe  20  is connected to the discharge tubes  42  of the holding tank  14  to be emptied. The other end of the holding tank output pipe  20  is connected to the inlet of the second vacuum unit  18 . The remaining space within the top of the holding tank  14  is then pressurised (while the discharge valves  38  are closed) either using an additional pressure source such as a pneumatic pump or the air compressor or using the first vacuum unit  12  in its pump mode. This pressurised zone results in the contents of the holding tank  14  being urged towards the bottom of the tank  14 . The discharge valves  38  on the bottom of the holding tank  14  are then opened and the tank  30  on the second vacuum unit  18  is then filled by creating a vacuum in the tank  30  in a similar way to that previously described for the first vacuum unit  12 . The vacuum  50  created along the output pipe  20  by the second vacuum unit  18  (combined with the pressure exerted on the drill cuttings  48  within the holding tank  14  by the pressurised zone) draws the drill cuttings  48  from the holding tank  14 . When the tank  30  on the second vacuum unit  18  is filled with drill cuttings  48 , the vacuum unit is switched off in preparation for pumping the drill cuttings  48  into the transportation tank  22  located on, for example, the supply vessel. A number of these transportation tanks  22  may be provided on the supply vessel e.g. from 1 to 20 tanks in order to maximise the drill cutting transport capacity of the supply vessel. 
         [0059]    When the unit  18  is switched to pumping mode it begins to pump the drill cuttings  48  along the transfer pipe  24  by introducing compressed air into the tank  30 . While the drill cuttings  48  are being pumped along the transfer pipe  24 , the third vacuum unit  28  simultaneously operates in its vacuum mode in order to create a vacuum along the vacuum pipe  26 . The vacuum present in the vacuum pipe  26  is communicated to the inside of the transportation tank  22  due to the open end of the vacuum pipe  26  provided by the vacuum pipe inlet aperture  46 . The effect of the pumping action provided by the second vacuum unit  18  combined with the vacuum created in the transportation tank  22  provides a large pressure differential across the drill cuttings  48  travelling along the length of the transfer pipe  24 . The magnitude of this pressure differential is substantially greater than that obtainable by only performing one of the pumping or sucking operations and is ideally suited to ensuring that the viscous material e.g. drill cuttings (which have a tendency to stick together and block pipes components) continue to flow through the apparatus  10 . This is even true over the relatively long distance required to transfer the drill cuttings  48  (through the transfer pipe  24 ) from the rig platform to the supply vessel. 
         [0060]    When the drill cuttings  48  reach the internal inlet aperture  34 A they escape into the transportation tank  22  and fall under the action of gravity toward the bottom of the tank  22 . It should be noted that the pressure differential across the transportation tank inlet aperture  34 A and the vacuum pipe inlet aperture  46  is not great enough to suck the drill cuttings across the gap between these apertures. A filter may also be provided on the aperture  46  to further prevent the material from entering the aperture and hence the vacuum unit  28 . In this regard, when the drill cuttings  48  within the transportation tank  22  reach a certain level the transfer operation should be switched to another transportation tank (not shown) since if the transportation tank  22  is over filled, drill cuttings  48  would be more likely to enter the vacuum pipe  26 , which is undesirable. When each transportation tank  22  on the vessel has been filled to the desired level, the transportation tank input pipe  24  is disconnected and the vessel may proceed to the onshore based processing/disposal facility. 
         [0061]    The cone  40 ,  40 A in the holding tank  14  and transportation tank  22  respectively serve to divide the drill cuttings  48  falling from the inlets  34 ,  34 A between the chutes  36 ,  36 A. The relatively small cross section of the plurality of chutes  36 ,  36 A (when compared to the situation if only a single chute were located on the bottom of the tanks  14 ,  22 ) provide a number of smaller individual areas upon which the material above can press upon which makes hard packing of the drill cuttings located at the bottom of the tanks  14 ,  22  less likely. 
         [0062]    When the transportation tanks  22  are to be emptied the remaining space within the top of the transportation tank  22  can be pressurised (while the discharge valves  38 A are closed) either using an additional pressure source such as a pneumatic pump (not shown) or using the third vacuum unit  28  in the pump mode (and/or if it is available, the second unit  18 , as will be described subsequently). This pressurised zone results in the contents of the transportation tank  22  being urged towards the bottom of the tank  22  in a similar fashion to that previously described for the holding tank  14 . The discharge valves  38 A on the bottom of the transportation tank  22  are then opened and the contents either removed simply due to the pressurisation in the transportation tank  22  or by attaching it to a further vacuum unit (not shown). 
         [0063]    Modifications and improvements may be made to the embodiments hereinbefore described without departing from the scope of the invention. 
         [0064]    For instance, although the embodiment of the apparatus  10  described above is used to transfer drill cuttings, the apparatus  10  may be used to transfer any material which will flow through a pipe, and is particularly useful for transporting materials which would otherwise tend to become stuck in pipes. 
         [0065]    The vacuum units  12 ,  18  may be substituted with any vacuum unit, particularly those capable of both acting as a vacuum and as a pump without becoming clogged with the material passing though it. The vacuum unit  28  may be substituted by a unit capable of creating a powerful enough vacuum. 
         [0066]    Furthermore, the second vacuum/pumping unit  18  could instead be situated on the supply vessel rather than on the drilling rig; in this case, the transfer pipe would be regarded as pipe  20  (suitably lengthened) and the pipe  24  would be suitably shortened. 
         [0067]    Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are within the scope of the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.