WO2005099856A2

WO2005099856A2 - An apparatus and a method for extracting granular and/or waxy material from a separation or other process vessel

Info

Publication number: WO2005099856A2
Application number: PCT/GB2005/001439
Authority: WO
Inventors: David Andrew Torrens Thomson; Alex Darling; Marc Forbes
Original assignee: Salamis Group Limited
Priority date: 2004-04-15
Filing date: 2005-04-15
Publication date: 2005-10-27
Also published as: GB0507629D0; GB0408419D0; WO2005099856A3; GB2414168A

Abstract

An apparatus for extracting granular or waxy material (12) from a production vessel (14), typically a separation vessel, is described. The apparatus includes an inlet/outlet (16) for allowing a lance (20) to enter the production vessel (14). The lance introduces a fluid, through a specially shaped nozzle (22), into said production vessel (14) to increase flowability of said granular or waxy material (12) which has settled at the bottom of the vessel (14). The apparatus includes one of more collection vessels (24) connected to the inlet/outlet (16) and is adapted to receive said granular or waxy material (12). In use the production vessel (14), inlet and outlet (16) are maintained under a pressure substantially the same as the working pressure of the production vessel (16) in order that the production vessel (16) can remain in operation during the extraction process. A hydraulic ram (26) for moving the lance (20) and a device (30) for retrieving the apparatus in the event of the lance (20) becoming stuck in the production vessel (14) are also described.

Description

An apparatus and a method for extracting granular and/or waxy material from a separation or other process vessel

The present invention relates to an apparatus and method for extracting granular and/or waxy material from a separation or other process vessel and relates particularly, but not exclusively, to the removal of sand from a separation vessel used on an oil production facility or as part of a crude oil production process. The invention also relates to a hydraulic ram and to a method and apparatus for retrieving a lance from a separator vessel.

It is a well known problem facing crude oil production facilities that sand can be extracted together with oil, gas and water from the oil reservoir. The presence of sand in the uplifted oil, water and gas, commonly termed the process fluids, causes major operational difficulties whether the oil is being uplifted offshore or on dry land. In particular, sand causes abrasion of and erosion to moving parts such as pumps and valves and to non-moving parts such as pipework. It also tends to cause constriction of the flow of the process fluids. As well as the cost of repairs, these problems result in oil pipeline operators applying restrictions on the proportion of sand, which they allow to be pumped through their pipelines from offshore oil facilities to onshore terminals, refineries and/or storage facilities.

Since the process fluids commonly contain significant amounts of oil, water and gas, it is normal practice for these fluids to be passed through various production vessels, including a separation vessel. In such a separation vessel the flow of the process fluids is slowed so that the immiscible elements of the fluids, the oil, water and gas have sufficient time to separate and be extracted. At the same time, the sand sinks through the oil and water layers and forms a layer at the bottom of the separation vessel. This layer of sand can then be removed. Layers of sand may also form in other productions vessels. Similarly higher density waxy materials, such as bitumen, may be present in the process fluids and may similarly congregate in layers at the bottom of process vessels.

The sand and waxy materials may be removed by extracting all of the oil, water and gas and entering the separation vessel to manually extract the layer of sand. This method suffers from the disadvantage that it requires the separation vessel to be shut down thereby causing the loss of production from the oil production faciiity. Furthermore, entry of personnel into a separation vessel has significant well known safety disadvantages.

The sand may also be removed by use of internally fitted sand jetting equipment which has been installed previously. This method uses pressurised water to fluidise the sand which is then drained from the vessel for treatment elsewhere. This method suffers from the disadvantage that it is permanently installed withϊ n the separator vessel and is often damaged before it is used.

An alternative extraction method is described in US6021787. In this method a lance is inserted into the sand layer and water is injected into the vessel. This causes the fluidisation of the sand which is extracted through an outlet, whi ch is generally the same pipe as the inlet through which the lance is inserted. This method also has the disadvantage that the separation vessel must be shut down before this operation can be undertaken. Such a cleaning operation may take a number of days and loss of production from an oil production facility for this period of time. This causes significant financial losses from the time during which the facility is shut down. As a result, the extraction of sand from the separation vessel is often only undertaken once every few years and therefore the separator may become significantly less efficient since its volume is effectively reduced by the presence of the layer of sand.

Preferred embodiments of the present invention seek to overcome problems with the prior art.

According to an aspect of the present invention, there is provided an apparatus for extracting granular or waxy material from a production vessel, typically a separation vessel, the apparatus comprising:- at least one inlet for allowing at least one lance to enter a production vessel; at least one lance for introducing at least one fluid into said production v& ssel to increase flowability of said granular or waxy material within said production vessel; at least one outlet for removal of granular or waxy material from said production vessel; and at least one collection vessel connected to at least one outlet and adapted to receive said granular or waxy material, wherein in use said production vessel, at least one said inlet and at least one said outlet are maintained under a pressure substantially the same as the working pressure of the production vessel.

By providing a pressurised inlet, through which a lance can be introduced into a production or separation vessel, and an outlet through which fluidised sand can b e extracted, the advantage is provided that the separation vessel can remain r n operation whilst sand is removed from the base of the separation vessel. With vessels of this type processing extracted fluids and producing 100,000 Barrels of crude oil per day or more, it is clear that there are significant advantages in being able to extract the sand from the vessel without the need to shut the vessel down an d incur significant losses in revenue. Furthermore, because the sand can be extracted from the separation vessel more frequently, it is possible to keep the volume of sand contained within the separation vessel down to a significantly lower level than was previously possible. This will in turn increase the efficiency of the separation vessel by effectively returning the volume within the vessel closer to the volume available in the clean condition. Therefore less sand will be carried through the separation vessel thereby reducing the wear on downstream components, which in turn wi II have a significant impact on the efficiency of and operating costs of the overa II process.

In a preferred embodiment at least one said lance comprises at least one hydraulically controlled device for moving at least one said lance between a working and a non-working position.

By using a hydraulically controlled lance, the advantage is provided that a standard and controlled force may be applied to the lance on insertion and removal from the separation vessel. This reduces the likelihood of the lance becoming caugh or entangled within the separation vessel. In the event that the lance does become entangled within the separation vessel, the extraction process would have to be stopped in order that the lance could be retrieved. As a result, it is clear thai: apparatus which assists in the consistent insertion and removal of the lance has significant advantages. The hydraulically controlled device may further comprise at least one high integrity mechanical seal through which at least one piston extends.

By using a hydraulically controlled device having a high integrity mechanical seal the advantage is provide that the seal, which is design to withstand the high pressure of hydraulic fluid within the device, can be utilised within the extraction apparatus at the high working pressure of the separation vessel. The seal can be described as acting like a valve, preventing fluids escaping the separation vessel, with a movable piston extending through it. Thus a hydraulic ram located outside the pressurised apparatus can be connected to the pressurised separation vessel and the high integrity mechanical seal prevents any leakage of the contents of the vessel. In the oil industry this is of particular importance since any such leakage, especially of gases, is likely to contravene safety standards and is therefore unacceptable.

In another preferred embodiment at least one said hydraulically controlled device comprises at least one hydraulic ram having:-

at least one cylinder having at least one first aperture and at least one second aperture;

at least one elongate piston having at least one respective first piston portion extending through at least one said first aperture and at least one respective second piston portion extending through at least one second aperture, wherein at least one said piston has at least one bore extending from said first piston portion to said second piston portion.

The apparatus may further comprise at least one retrieval device having:-

at least one gripping device for gripping at least one portion of a lance;

at least one cutting device for cutting said lance externally of the vessel and thereby forming a first portion of said lance at least partially contained within said vessel and a second portion of said lance at least partially external of said vessel;

at least one lance withdrawing device for withdrawing said second portion of said lance; at least one valve for preventing the flow of fluid along an inlet conduit; and

at least one inlet conduit separator for separating one portion of said inlet conduit from another.

By providing a method for severing a lance, when it is realised that the lance has become stuck within the separation vessel and cannot be removed, the lance being cut outside of the separation vessel and the external portion withdrawn allowing the isolation of the apparatus from the vessel, the advantage is provided that the separation vessel can continue to run until the next scheduled shutdown which may be several years. As previously mentioned, any period of time in which the process can remain running has significant revenue generating implications. Once the lance has been cut it can be replaced and the apparatus used elsewhere without having to leave it connected to the separator and maintain the pressure within it. The apparatus can be fitted with a new lance and nozzle and the vessel re-entered at another inlet to continue the process.

In a preferred embodiment at least one said lance withdrawing device comprises at least one hydraulically controlled device.

In a preferred embodiment, at least one said inlet and at least one said outlet comprise at least one conduit.

In another preferred embodiment in use at least one said collection vessel and the connecting system of pipework are maintained at substantially the same pressure as at least one said production vessel.

The apparatus may further comprise at least one choke. in a preferred embodiment said choke may be located between at least one said outlet and at least one said collection vessel for reducing the pressure of the granular or waxy material and fluid mix before it enters the collection vessel.

By locating a choke before the collection vessels, the advantage is provided that the apparatus can be used for production vessels which run at a higher pressure than the maximum pressure of the extraction apparatus. The choke may alternatively be located downstream of said collection vessel for controlling the rate of removal of granular or waxy material and fluid mix from at least one said outlet.

The apparatus may further comprise at least one gas removal system and said gas removal system may be located on at least one said collection vessel.

By providing a gas removal system, the advantage is provided that the apparatus may be connected to an operating separation vessel and be run on an oil extraction facility where normal health and safety practices are enforced. Small volumes of gas are regularly carried over in the produced water and must be safely contained.

According to another aspect of the present invention, there is provided a method of extracting granular or waxy material from a production vessel, typically a separation vessel, the method comprising the steps o - at least partially inserting at least one lance into a production vessel through at least one respective inlet; introducing at least one fluid, through said lance, into at least one layer of granular or waxy material and thereby causing at least a portion of said granular or waxy material to be expelled through at least one outlet, wherein the pressure in said production vessel, at least one said inlet and at least one said outlet are substantially the same as the working pressure of the production vessel.

In a preferred embodiment the method further comprises removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit by:-

gripping at least one portion of a lance;

cutting said lance externally of the production vessel, thereby forming a first portion of said lance at least partially contained within said vessel and a second portion of said lance at least partially external of said vessel;

withdrawing said second portion through at least one valve; closing at least one said valve; and

removing at least a portion of at least one said inlet.

In a preferred embodiment said lance is gripped within at least one said inlet conduit and between the portion of the lance that is cut and the production vessel.

In a preferred embodiment said first portion of said lance remains gripped after the lance has been cut.

According to a further aspect of the present invention, there is provided a method of removing a fluid injecting lance which extends into a production vessel through at least one inlet, the method comprising:- gripping at least one portion of a lance; cutting said lance externally of the production vessel, thereby forming a first portion of said lance at least partially contained within said vessel and a second portion of said lance at least partially external of said vessel; withdrawing said second portion through at least one valve; closing at least one said valve; and removing at least a portion of at least one said inlet conduit.

By providing a method for severing a lance, when it is realised that the lance has become stuck within the separation vessel and cannot be removed, the lance being cut outside of the separation vessel and the external portion withdrawn allowing the isolation of the apparatus from the vessel, the advantage is provided that the separation vessel can continue to run until the next scheduled shutdown which may be several years. As previously mentioned, any period of time in which the process can remain running has significant revenue generating implications. Once the lance has been cut it can be replaced and the apparatus used elsewhere without having to leave it connected to the separator and maintain the pressure within it. The apparatus can be fitted with a new (ance and nozzle and the vessel re-entered at another inlet to continue the process.

In a preferred embodiment, said lance is gripped within at least one said inlet conduit and between the portion of the lance that is cut and the production vessel.

In another preferred embodiment, said first portion of said lance remains gripped after the lance has been cut.

By gripping the first portion of the lance, after it is cut, the advantage is provided that the portion of the lance remaining in the separation vessel does not become dislodged and cannot interfere with the separation process.

According to another aspect of the present invention, there is provided an apparatus for removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit, the apparatus comprising:- at least one gripping device for gripping at least one portion of a lance; at least one cutting device for cutting said lance externally of the vessel and thereby forming a first portion of said lance at least partially contained within said vessel and a second portion of said lance at least partially external of said vessel; at least one lance withdrawing device for withdrawing said second portion of said lance; at least one valve for substantially preventing the flow of fluid along an inlet conduit; and at least one inlet conduit separator for separating one portion of said inlet conduit from another.

In a preferred embodiment, at least one said lance withdrawing device comprises at least one hydraulically controlled device.

According to a further aspect of the present invention, there is provided a hydraulic ram comprising:- at least one cylinder having at least one first aperture and at least one second aperture; at least one elongate piston having at least one respective first piston portion extending through at least one said first aperture and at least one respective second piston portion extending through at least one second aperture, wherein at least one said piston has at least one bore extending from said first piston portion to said second piston portion.

By providing a hydraulic ram containing a bore extending through a piston, the advantage is provided that the hydraulic ram can be used to control the insertion and extraction of the lance and the bore through the piston can carry the fluid which is introduced through the lance into the layer of sand. In particular, where the bore extends axially into one end of the piston, the advantage is provided that the connectors for the high pressure hoses which are connected to the piston can be attach axially. This in turn allows the piston to have a smaller diameter than if the high pressure hose was to be attached at right angles to the axis of the piston. This is because it would be necessary to flatten the curved surface of the piston so as to form a seal between the end of the hose and the piston. Furthermore, in order to provide sufficient turns of thread into the piston for the high pressure hose to successfully connect and sealed with piston, the piston diameter would have to be considerably greater still.

The hydraulic ram may further comprise at least one high integrity mechanical seal through which said piston extends.

Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense, in which:-

Figure 1 is a schematic view of an extraction apparatus of the present invention;

Figure 2a is a schematic sectional view of a pipeline embodying part of an extraction system of the present invention; Figure 2b is a schematic sectional view of a pipeline of an alternative embodiment to that shown in Figure 2a;

Figure 3 is a schematic view of the components forming a portion of the extraction apparatus of the present invention in the form of an inlet conduit;

Figure 4 is a side view of a sleeve "Y" piece used in the present invention;

Figure 5 is a series of views and sectional views of a nozzle formed on the end of a lance of an extraction system of the present invention;

Figures 6a and 6b are front and plan views respectively of a first blade portion of a cutting mechanism of the present invention;

Figures 6c and 6d are a side view and plan views respectively of a second blade portion of a cutting mechanism of the present invention;

Figure 6e is a side view of a cutting mechanism of the present invention;

Figures 6f, 6g and 6h are side, plan and end views the block within which the cutting mechanism of figures 6a to 6e are contained;

Figure 6i is an exploded view of a cutting mechanism of another embodiment of the invention shown in Figures 6a to 6f;

Figure 7a is a side view of a hydraulic ram of the present invention;

Figure 7b is a sectional view along the line A-A;

Figure 7c is an end view of the hydraulic ram of Figure 7a;

Figure 7d is a close up view of part of Figure 7b; and

Figure 8 is a front view of collection vessel of the present invention.

Referring to Figures 1 , 2a and 3, an apparatus 10 for extracting granular or waxy materials, typically sand 12, from a production vessel, in this instance a separation vessel or bulk separator 14, has an inlet conduit 16, which is attached to an inlet valve 18 on bulk separator 14. Bulk separator 14 is provided with further inlet valves 18. The apparatus 10 also has a flexible lance 20 with a head 22 which in use is inserted into the bulk separator 14 along inlet conduit 16 and through valve 18. The inlet conduit 16 also acts as an outlet for removal of the sand solids and fluids 12 and is connected to collection vessels 24a, 24b, 24c and 24d.

Lance 20 is used to introduce water under high pressure, through head 22, into sand 12. This fiuidises the sand and causes it to flow through inlet/outlet conduit 16 and valve 18.

Lance 20 is moved along inlet/outlet pipe 16 by use of hydraulic tool 26, which is provided with a high integrity mechanical seal 27. The lance 20 is introduced into inlet/outlet conduit 16 through a sleeved "Y" piece 28 and extends through a valve 30 and a crimp and shear assembly 32. As shown in Figure 4, the sleeved Y-piece 28 has an inlet 28a and a first pipe extending therefrom through which lance 20 is inserted. A second outlet 28c is connected to collection vessels 24a to 24d.

The high pressure water pumped along lance 20 and out of head 22 is controlled by high pressure water jetting unit 34. Reference to high pressure means water at a pressure higher than the pressure within the separator vessel. The high pressure water jetting unit 34 has an accompanying emergency shut down valve control unit 35 which controls emergency shut down valves 36, 37, 38 and 39.

A choke 40a may also be provided which allows for a difference in the working pressure of the bulk separator 14 and the collection vessels 24a to 24d. Further choke 40b and 40c may be included to control flow of water before it is returned to the separator vessel. A motive pump 41 may also be provided to pump the fluidised sand towards the collection vessels 24a to 24d.

With reference to Figures 1 and 8, collection vessels 24a to 24d are worked under the control of valve systems 42 and 44a to 44d. The collection vessel 24 shown in Figure 8 is a general example of any of the collection vessels 24 a to 24d shown in Figure 1. Selection of the collection vessels 24a to 24d is controlled by respective valve systems 44a to 44d. As the fluidised sand enters the collection vessel, through inlets 45a to 45d, it will typically predominantly contain sand with sufficient water to effect the fluidisation and limited but potentially significant levels of oil and gas. Once the solids have separated within the collection vessel, the oil and water mix is extracted through outlets 46a to 46d, under the control of valve systems 48a to 48d. Typically the water effluent with oil mixed therein is returned via motive pump 50 if necessary and control valve system 52 to the bulk separator 14. This may be done through inlet valves 54 into the bottom of the bulk separator. This would be advantageous where very little oil is present in the effluent since, as the water will enter the sand it will assist in the fluidisation of the sand layer 12. Alternatively, the effluent could be introduced into the bulk separator together with or adjacent to the main entry point (not shown) for the process fluids entering the bulk separator 14, or otherwise into the operator's system. In either of these two alternatives the entire system remains pressurised at the working pressure of the bulk separator. As a further alternative the effluent could be introduced into a lower pressure produced water handling system (not shown) which typically is present in oil processing facilities. The effluent from the collection vessel 24a to 24d may be removed and cleaned for returning to the environment by separate apparatus not forming part of the facility's existing oil separation system.

The collecting vessels 24a to 24d have respective pressure gauges 55 as well as gas removal systems, 56a to 56d, which may be connected into the existing gas processing system of the oil production facility or sent to a suitable vent or flare. By keeping the collecting vessels 24a to 24d at the pressure of the bulk separator gas removal requirements will be very minimal since the gas will remain dissolved in the water.

Once the collection vessels 24a to 24d are either full or the process has been completed, the solids can be extracted through outlets 58a to 58d.

During the sand extraction process, an acoustic monitor 60 or other similar instruments may be used to determine the thickness of the sand layer within the bulk separator.

Referring to Figure 5, nozzle 22 has a threaded inlet 70 for attachment to lance 20. Head 22 also typically has five threaded outlets 72a to 72e into which jetting nozzles (not shown) may be inserted. The angle through which the jetting nozzles expel water may be varied, typically ranging from 0 to 70°, dependent upon the conditions and internal architecture , within the separator vessel. Referring again to Figures 1, 2a and 8, in use inlet/outlet conduit 16 is connected to valve 18 which forms part of separation vessel 14. At the same time, at least one of the outputs 46a to 46d of collector vessels 24a to 24d are connected to at least one valve 54 and the gas removal systems 56a to 56d are connected to the gas control system at the facility. The connecting valve 18 may be slowly opened thereby gradually increasing the pressure within the sand extraction apparatus 10. Once the pressures within the bulk separator and the sand extraction apparatus 10 are substantially in equilibrium. The hydraulic control unit is activated so as to push the lance 20 from its non-working condition, in which the head 22 is located within inlet/outlet conduit 16 close to connection valve 18, to its working condition extending into the sand layer 12 in sand separator 14.

Once in this working condition, the high pressure jetting unit 34 is activated and potable or treated sea water is injected through the bore of the hydraulic too! 26 along lance 20 and out through jetting nozzles 72a to 72e in head 22. As a result of this introduction of fluid into sand layer 12, the sand becomes fluidised and passes through valve 18 and inlet/outlet conduit 16, running along the annular space formed between lance 20 and the sides of the inlet/outlet conduit 16, the lance 20 being much narrower than the internal bore of inlet/outlet conduit 16. The fluidised sand passes through crimp and shear mechanism 32 and through valve 30 passing through sleeved Y-piece 28 from inlet 28a to outlet 28c. The fluidised sand is unable to travel along outlet 28b because it ends in a dead end at the high integrity mechanical seal 27 of hydraulic tool 26. The fluidised sand passes through emergency shutdown valve 38 and if present through choke 40 where the pressure of the fluid passing therethrough may be reduced. The fluid may then be pumped using motive pump 41 into one of the collection vessels 24a to 24d. The intent of the pressurised system is to provide true on-line cleaning.

Where waxy materials are extracted from the vessel, steam or high pressure steam may be used instead of water to melt or reduce the viscosity of the materials thereby allowing them to flow into and through inlet/outlet conduit 16. The use of this process may require the conduit 16 and other parts between the separation vessel 14 and collection vessels 24a and 24d to be insulated against heat loss or even heated. The collection vessel to be used is selected by opening one of the valves 42 and one of valves 44a and 44b or 46c and 44d. Once the first collection vessel, for example 24a, is full, valve 44b is open and valve 44a shut off so that the second collection vessel 24b can be filled. Once the fluids in collection vessel 24a have settled, the outlet valve system 48a is opened and the liquid from collection vessel 24a can be pumped, by pump 50, along outlet 48a. The liquid effluent passes from pump 50 through emergency shutdown valve 37 and further valve 52 and passes back into bulk separator via valve 54. Throughout this process, gas vent 56a allows removal of gases which are typically returned to the facility's main gas maintenance system. Once the liquid component has been removed from collection vessel 24a, the sand remains in the collection vessel until the system is disconnected. The sand can then be extracted through outlet 58a from which it is cleaned to remove further oil and disposed of by a suitable known method.

It will be clear to the skilled person that although this apparatus would work with a single collection vessel, it is advantageous to have multiple collection vessels in order to allow a continuous process to run without stopping and waiting for a filled collection vessel to be emptied. Therefore two, or typically more, collection vessels are involved. Once sufficient sand 12 has been removed from around the first inlet valve 18, as determined by using acoustic monitoring system 60 or some other known method, the inlet/outlet conduit 16 is connected to the next inlet valve 18 of bulk separator 14 and the process repeated.

Thus it can be seen that the pressure of the bulk separator 14 can be maintained by maintaining pressure throughout the extraction apparatus and this is in particular the case where all effluents, with the exception of the extracted sand, are returned to the main processing system of the facility on w ich the bulk separator is located. Therefore, this apparatus provides an intervention process which is carried out on an operating vessel whilst maintaining the integrity of fluids, gases and pressure containment of the host production system.

Referring to Figures 2a and 6a to 6e, an apparatus 32 for severing a lance injecting fluid into a separation vessel includes a first blade portion 80 having a cutting surface 82 with shearing edges 84. The first cutting portion 80 also has channels 86 to receive guide pins 88, shown in Figure 6e. A second cutting portion 90 has cutting surfaces 92 and a recess 94 sized to receive first cutting portion 80. Apertures 96 receive guide pins 88. The assembly including first and second blade portions 80 and 90 and guide pins 88 is formed as a sealed unit within the inlet/outlet conduit 16, the bore of which is indicated in Figures 6d and 6e as 98. In figures 6f, 6g and 6h the block which contains the above described cutting mechanism is contained is shown. The bore 98 of inlet/outlet conduit 16 is shown perpendicular to bore 99 which contains the cutting mechanism.

The cutting apparatus 32 is only for use when the lance 20 becomes stuck within separation vessel 14 and cannot be removed. In this instance it would normally be necessary to either leave the sand extraction apparatus connected to the bulk separator, thus preventing its continued use until the lance can be freed. In order to free the lance it will be necessary to shut down the separator to gain access. It is therefore advantageous if the separator can be maintained under pressure and the sand extraction apparatus can be removed until such time as the trapped portion of the lance can be retrieved, which may not be for a period of several years at the next planned production shutdown.

If the lance 20 is stuck and cannot be removed, the cutting device 32 is activated by a hydraulic ram (not shown) which causes the first blade portion 80 to travel in a direction D, as shown in Figure 6e, so as to trap hose 20 within the V- shaped surface 82 of first blade portion 80.

The blade portion 80 continues in direction D and will enter into recess 94 of second blade portion 90 and a shearing force will be provided between the surfaces 92 and edges 84, thus cutting hose 20.

The whole process for removing the sand extraction apparatus from the bulk separator in the event that the lance 20 becomes trapped is as follows. The high pressure water jetting unit 34 will have been turned off before the attempted retraction of lance 20. Once the lance has been cut, it will be held in place by the gripping mechanism, this will prevent the lance from becoming loose and entering into the bulk separator. The cutting mechanism 32 is activated so as to cut lance 20 and the hydraulic control unit 26 can then be activated to withdraw the cut lance through valve 30. Once the cut end of the lance has passed valve 30, this valve can be closed and the sand extraction apparatus disconnected at valve 30 rather than valve 18 as would normally be the case. As a result, the closed valve 30 maintains the pressure within the bulk separator which can continue to function until it is finally shut down when retrieval of lance 20 may take place. Referring to Figures 2b and 6i, in an alternative embodiment, the cutting apparatus is divided into two distinct parts, namely a clamping or crimping part 32a and a cutting part 32b. The clamping part 32a is included to make sure that once the lance has been cut it cannot become dislodged from the position where it is stuck, enter the separation vessel and cause damage within that vessel. The cutting part 32b, which is located nearer the valve 30, cuts the lance so that the remainder of the apparatus can removed from the separation vessel. The cutting device has a V- shaped blade 80 which runs along guide 96 and cuts using a shearing cut against cutting surface 92. The blade 80 is controlled by piston rod 91 of hydraulic ram 93 which pushes the blade along bore 99, thereby crossing the bore 98 through which the lance 20 extends.

Referring to Figure 7a to 7d, the hydraulic control unit or hydraulic ram 26, which controls the insertion and withdrawal of lance20, has a cylinder 100 having a first aperture 102 and a second aperture 104. Ram 26 also has a piston 106 which has a piston rod 108 and piston head 110. Piston rod 108 has a first end 1 12 and a second end 1 14. A bore 115 extends axially along piston rod 108 from first end 1 12 to second end 1 14. Cylinder 100 has first and second inlets/outlets 116 and 118 which are connected to a hydraulic pump and allow hydraulic fluid to be passed in and out of the cylinder thereby moving piston head 110 thereby moving the whole piston 106.

Hydraulic ram 26 also includes a high integrity mechanical seal 1 18. Seal 118 includes a flange 120 for connection to the extraction apparatus. There is also a metal to metal high integrity seal 122 which accurately engages the outer surface or piston rod 108. Behind seal 122 is gland housing contain gland packing 124. The housing may be formed from phosphor bronze and the packing may be of the type provided by Klinger UK Limited known as Klinger TopLine K322. This high integrity seal 118 is able to withstand the pressure of the fluidised sand within the inlet/outlet conduit wh ich is typically at a pressure of 40 Bar (4 MPa) and can therefore be connected into the pressurised separating vessel. The fluids in the separating vessel cannot leak through the high integrity seal it being designed to withstand pressures in excess of those of the vessel, and thus the integrity of the vessel is maintained whilst allowing the lance to be inserted and withdrawn. ln use, first end 112 is connected to a high pressure jetting unit 34 and second end 114 is connected to lance 20. In the retracted position the piston head 110 is adjacent first inlet 116 and upon introduction of hydraulic fluid through inlet 116, piston head 110 moves towards second inlet 118. As a result, piston rod 108 moves in the same direction thereby pushing lance 20 into the separation vessel. This process is reversed by pumping hydraulic fluid into inlet 118 causing the head to move towards inlet 116. The cylindrical casing 126 extending from seal 1 18 to second aperture 104 of cylinder 100 is provided with a viewing window 128 which is used to determine the technical integrity of seal 118. Once the lance 20 has been pushed into position, high pressure fluid, generally water, can be pumped along bore 115 through lance 20 and into the pressurised separation vessel.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. For example this process and apparatus are not restricted to use within the oil industries and may be used in any production or processing system where granular or waxy materials are inclined to settle within production and process vessels, such as pharmaceutical production.

Claims

1. An apparatus for extracting granular or waxy material from a production vessel, typically a separation vessel, the apparatus comprising:-

at least one inlet for allowing at least one lance to enter a production vessel;

at least one lance for introducing at least one fluid into said production vessel to increase flowability of said granular or waxy material within said production vessel;

at least one outlet for removal of granular or waxy material from said production vessel; and

at least one collection vessel connected to at least one outlet and adapted to receive said granular or waxy material, wherein in use said production vessel, at least one said inlet and at least one said outlet are maintained under a pressure substantially the same as the working pressure of the production vessel.

2. An apparatus according to claim 1 , wherein at least one said lance comprises at least one hydraulically controlled device for moving at least one said lance between a working and a non-working position.

3. An apparatus according to claim 2, wherein at least one said hydraulically controlled device further comprises at least one high integrity mechanical seal through which at least one piston extends.

4. An apparatus according to claim 3, wherein at least one said hydraulically controlled device comprises at least one hydraulic ram having:-

5. An apparatus according to any one of the preceding claims, further comprising at least one retrieval device having :-

at least one gripping device for gripping at least one portion of a lance;

at least one lance withdrawing device for withdrawing said second portion of said lance;

at least one valve for substantially preventing the flow of fluid along an inlet conduit; and

6. An apparatus according to claim 5 wherein at least one said lance withdrawing device comprises at least one hydraulically controlled device.

7. An apparatus according to any one of the preceding claims, wherein at least one said inlet and at least one said outlet comprise at least one conduit.

8. An apparatus according to any one of the preceding claims, wherein in use at least one said collection vessel is maintained at substantially the same pressure as at least one said production vessel.

9. An apparatus according to any one of claims 1 to 7, further comprising at least one choke.

10. An apparatus according to claim 9, wherein at least one said choke is located between at least one said outlet and at least one said collection vessel for reducing the pressure of the granular or waxy material and fluid mix before it enters the collection vessel.

11. An apparatus according to claim 9, wherein at least one said choke is located downstream of said collection vessel for controlling the rate of removal of granular or waxy material and fluid mix from at least one outlet.

12. An apparatus according to any one of the preceding claims, further comprising at least one gas removal system.

13. An apparatus according to claim 12, wherein at least one said gas removal system is located on at least one said collection vessel.

14. An apparatus for extracting granular or waxy material from a production vessel, typically a separation vessel, substantially as hereinbefore described with reference to the accompanying drawings.

15. A method of extracting granular or waxy material from a production vessel, typically a separation vessel, the method comprising the steps of:-

at least partially inserting at least one lance into a production vessel through at least one respective inlet;

introducing at least one fluid, through said lance, into at least one layer of granular or waxy material and thereby causing at least a portion of said granular or waxy material to be expelled through at least one outlet, wherein the pressure in said production vessel, at least one said inlet and at least one said outlet are substantially the same as the working pressure of the production vessel.

16. A method according to claim 15, further comprising removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit by:-

gripping at least one portion of a lance;

cutting said lance externally of the production vessel , thereby forming a first portion of said lance at least partially contained within said vessel and a second portion of said lance at least partially external of said vessel;

removing at least a portion of at least one said inlet.

17. A method according to claim 16, wherein said lance is gripped within at least one said inlet conduit and between the portion of the lance that is cut and the production vessel.

18. A method according to claim 16 or 17, wherein said first portion of said lance remains gripped after the lance has been cut.

19. A method of extracting granular or waxy material from a production vessel, typically a separation vessel, substantially as hereinbefore described with reference to the accompanying drawings.

20. A method of removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit, the method comprising:-

gripping at least one portion of a lance;

withdrawing said second portion through at least one valve;

closing at least one said valve; and

removing at least a portion of at least one said inlet.

21. A method according to claim 20, wherein said lance is gripped within at least one said inlet conduit and between the portion of the lance that is cut and the production vessel.

22. A method according to claim 20 or 21 , wherein said first portion of said lance remains gripped after the lance has been cut.

23. A method of removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit substantially as hereinbefore described with reference to the accompanying drawings.

24. An apparatus for removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit, the apparatus comprising:-

at least one gripping device for gripping at least one portion of a lance;

25. An apparatus according to claim 24 wherein at least one said lance withdrawing device comprises at least one hydraulically controlled device.

26. An apparatus for removing a fluid injecting lance which extends into a production vessel through at least one inlet conduit substantially as hereinbefore described with reference to the accompanying drawings.

27. A hydraulic ram comprising:-

28. A hydraulic ram according to claim 27, further comprising at least one high integrity mechanical seal through which said piston extends.

29. A hydraulic ram substantially as hereinbefore described with reference to Figures 7a, b and c of the accompanying drawings.