APPARATUS

The present invention relates to treating, moving and removing particles in fluid- carrying apparatus. In one particular embodiment, the invention offers a method and means whereby solid contaminants can be removed from an interior surface of a pipeline.

Fluid-carrying apparatus, such as fluid transport pipes, storage tanks or containers, are widely known to be used in a number of industrial applications. In road constructions, materials may have to be transported from a storage location to a road location where a road surface may need to be built up. In the oil and gas industry, apparatus in the form of pipelines are used to move hydrocarbon products between locations often large distances apart. In addition, recovered oil and gas is typically transported via a sequence of pipe selections as they are pumped from the well, onto the well installation, and into pipeline for export to a refinery. Further, recovered hydrocarbons may be treated at a well installation or a refinery where the product may also be run though different kinds of tanks, for example, separation tanks to separate out different gases, or heavy and light oils.

In the production of oil and gas therefore, a hydrocarbon product will typically be passed through numerous pipe systems.

Over time, unwanted residues, waxes and dirt may build up inside the fluid- carrying apparatus. Solids which may be carried along with the fluid may fall out and be deposited inside the apparatus, and some substances may even become adhered to the inner surfaces of such apparatus.

These unwanted particles and residues may contaminate a product passing through a pipeline, and after a long-term build up may adversely affect the performance of a pipeline system. It is therefore desirable to periodically remove these particles and residues to clean out the system. It can also be desirable to treat a cleaned system with a coating to protect and resist build up of such residues.

From time to time therefore, the interiors of such pipeline systems need to be cleaned to remove both residues adhered to inner surfaces of the pipeline system, to collect up loose deposits which have settled out from the fluid, and to be treated with protective coatings.

There are a number of difficulties that arise with a view to cleaning such systems. For example, one problem is how to access the interior surfaces of the fluid-carrying apparatus. A further difficulty is how to perform the cleaning and/or treatment effectively.

At present, pipeline cleaning and treatment is often carried out using Pipeline Inspection Gauges (pigs), which are pumped through a pipeline. The pigs may be fitted with brushes or scrapers which extend to engage with interior surfaces of the pipeline to remove material. Material removed from the pipeline walls or deposited in the pipeline is pushed along the pipeline ahead of pig and removed at an access point further along the pipeline. Other elements may be used to coat a pipeline wall.

The pig technique has significant drawbacks. One difficulty is that the pig is designed with a specific diameter to engage a pipe section with a corresponding diameter. Thus, any one pig may not be suitable for cleaning or treatment where a pipeline diameter changes along its length, or where the pipeline transfers into other kinds of fluid carrying apparatus such as tanks in other parts of the system. Pigs are therefore susceptible to becoming stuck in a pipeline. This can be a particular problem where any debris is present in the pipeline.

In addition, due to pig elements having limited dimensions, the cleaning and/or treatment elements may not be effective at accessing and cleaning pits, dimples or creases which typically may be formed in inner surfaces of the pipeline.

Furthermore, pigs themselves typically need to be maintained and removed from the pipeline after use. To achieve this, a pig launching and receiving assembly may be provided which connects to the pipeline, and allows manual access to prepare, launch, replace or retrieve pigs. Such launching and retrieving operations can be inconvenient, time consuming and thus costly.

Another specific cleaning method involves a gel which is pumped through a pipeline. However, this technique is problematic because gels are highly viscous, such that particles or dirt removed from sides of a pipeline collects on an outer surface of the gel such that as the gel is moved along the collected dirt is further smeared against the interior pipe surfaces. Thus, after use of a gel, a second cleaning operation is often required to remove residues caused by use of the gel itself. In addition, the viscous nature of gels can give rise to blockages, particularly where material is pushed ahead of the gel and at restrictions in the pipeline system. Yet further, gels are expensive, and prohibitively so, if required to clean long-distance pipelines.

Yet further, removal of material build-ups in a pipe or tube system, for example, parafin wax build-up in an oil pipeline, is known to be carried out by passing specific solvents through the pipe to dissolve the material. However, this technique suffers in that solvent is often unevenly imparted to the pipe surface and it can be difficult to fully recover the solvent. Moreover, high volumes of solvent are often needed which can be costly.

Difficulties may also be encountered in connection with fluid-bearing pumps where solid particles, such as sand, are suspended in the fluid and settle out due to gravity, and can cause the pump to seize and stop functioning particularly when the pump is switched off. Solid particles that are settled out in this way may cause the pump to seize and stop running, and repair costs are typically high because pumps of this nature would typically need to be stripped down into component parts and replaced which is a time consuming process. In addition, dependent industrial processes may need to be halted while the pump is out of operation.

According to a first aspect of the invention, there is provided a clean-up fluid for cleaning fluid-carrying apparatus, the clean up fluid comprising a liquid and sufficient particles in admixture therewith to initiate a cleaning action in use within a fluid-carrying apparatus, wherein particles of fibre are dispersed in a volume of the liquid in an amount that does not exceed the particle-carrying capacity of that volume of liquid.

Such clean-up fluid may comprise abrasive particles and fibre particles in admixture in the liquid.

Therefore, the clean-up fluid can be applied to pick up and carry additional particles in the volume of liquid, such as contaminants, residues, sediments or other solids which may be present and/or deposited inside pipes, containers, settling tanks or other fluid-carrying apparatus. In this way, the clean-up fluid can clean away the additional particles.

The fibre particles and/or any such additional particles picked up by the fluid, may be suspended in the volume.

The fibre particles and/or any such additional particles picked up by the fluid, may be suspended in the volume.

The clean-up fluid may take the form of a slurry for being pumped through a pipeline, tubing, tank, container or other fluid-carrying apparatus to interact with interior surfaces of such fluid-carrying apparatus.

The clean-up fluid may comprise:

0.5-10% w/w fibre particles; and 90-99.5% w/w liquid.

The particles of fibre may comprise natural and/or synthetic fibre particles. More specifically, the natural and/or synthetic fibres may comprise plant fibres, paper fibres, and/or nylon, plastics, horsehair, and/or other fibres.

Preferably, the liquid comprises water. The liquid may comprise a saline liquid, such as salt water. The liquid may comprise an oil base, to take the form of an oil-based liquid.

The clean-up fluid may include a treatment agent for treating a surface of the fluid-carrying apparatus. The treatment agent may comprise a corrosion inhibitor or lubricant. The treatment agent may be adapted to apply a protective coating to the surface.

The clean-up fluid may include a solvent for treating a surface of the fluid- carrying apparatus.

In one embodiment, the clean-up fluid may be adapted to abrade an inner surface of a fluid-carrying apparatus. More specifically, the clean-up fluid may comprise abrasive particles. The abrasive particles may be adapted to abrasively remove said residues lining a pipeline wall, e.g. through a scraping action. The abrasive particles may be dispersed and/or suspended in the volume of the liquid. In this embodiment, the fibre particles dispersed in the volume of the liquid may provide support to allow the abrasive particles to be suspended in the volume. Thus, in use, the clean-up fluid can scrape off, agitate, and remove solid residues by the presence of abrasive particles, whilst the fibres dispersed in the volume allow particles that have been removed to be picked up and carried along the volume.

The clean-up fluid may comprise: 0.5-10% w/w/fibre particles;

0.5-10% w/w abrasive particles; and 80-99% w/w/ liquid.

The abrasive particles may comprise grit, sand, clays, quartz, diamond, and/or tungsten carbide particles. The abrasive particles may comprise particles of different dimensions, shapes, and/or sizes for facilitating cleaning of dimples or pits formed in a wall of a fluid-carrying apparatus and which may be of different scales.

The clean-up fluid is further adapted to permit the additional particles to be mixed into the volume in use. For example, the clean-up fluid may be adapted to act as a low viscosity fluid for facilitating mixing of additional particles into the volume. Thus, as the additional particles, such as solid residues, are removed and/or collected, the additional particles are readily mixed into the volume such that the clean-up fluid acquires a new constituency including the additional particles. In this way, the contaminant particles can effectively incorporated in the volume to be carried/transported with the clean-up fluid, e.g., upon being pumped through fluid-carrying apparatus.

In a specific embodiment, the clean-up fluid may take the form of a papier-mache mixture, wherein the liquid volume comprises water and the fibre particles comprise paper and/or newsprint-derived fibre particles in admixture.

The fluid-carrying apparatus may include pumps, tanks, containers, tubes, pipes or the like. According to a second aspect of the invention there is provided the use of a clean-up fluid according to the first aspect of the invention in the cleaning of fluid- carrying apparatus.

According to a third aspect of the invention, there is provided a method of cleaning fluid-carrying apparatus, the method comprising the steps of:

(a) mixing a liquid with fibre particles to form an admixture, the fibre particles being dispersed in a volume of the liquid in an amount that does not exceed the particle-carrying capacity of that volume of liquid; and (b) delivering the admixture into the fluid-carrying apparatus in a volume sufficient to carry additional particles encountered in the fluid-carrying apparatus in the delivered volume.

The method may comprise the step of adding abrasive particles to the admixture.

The fluid-carrying apparatus may include a pump, tank, tubing or the like.

The method may comprise the step of admixing constituents to form a low viscosity clean-up fluid. In this way, additional particles, such as contaminants, of the fluid-carrying apparatus are effectively admixed and can be carried with the volume of the clean-up fluid.

The method may comprise the step of pumping the clean-up fluid at pressure to force he clean-up fluid through the fluid-carrying apparatus for picking up additional particles such as residues or solid fallouts. The method may comprise the step of pumping the clean-up fluid into contact with interior surfaces of the fluid-carrying apparatus to scrape residue from the surfaces and/or collect and carry loosened residues.

The clean-up fluid may be a clean-up fluid according to the first aspect of the invention.

Other features of the third aspect of the invention may be defined with references to features of the first and second aspects. According to a fourth aspect of the invention, there is provided a method for transporting aggregate materials to a transport location, the method comprising the steps of:

(a) providing apparatus for containing aggregate materials; (b) mixing a liquid with fibre particles to form an admixture, the fibre particles being dispersed in a volume of the liquid in an amount that does not exceed the particle-carrying capacity of that volume of liquid; and (c) delivering the admixture to the apparatus in a volume sufficient to carry the aggregate materials in the volume; and (d) energising the delivered admixture to move the aggregate materials with respect to the apparatus to the transport location.

The apparatus may be tubing extending between a stockpile, container or other source of aggregate materials and a second location, which may be for example a road location, offloading location or other transport location. The aggregates may be road aggregates for use in constructing a road surface. Thus, the method may facilitate moving the road aggregates to a location where a road surface may need to be constructed.

The apparatus may include a pump. The pump may be adapted to energise the admixture.

Other features of the fourth aspect of the invention may be defined with reference to features or method steps of any one of the first to third aspects.

According to a further aspect of the invention, there is provided a treatment fluid comprising liquid and sufficient particles in admixture therewith for treating a fluid carrying apparatus, wherein particles of fibre are dispersed in a volume of the liquid in an amount that does not exceed the particle-carrying capacity of that volume of liquid.

The fluid may comprise a treatment agent for applying a protective coating to a surface of a fluid-carrying apparatus. The treatment agent may include a corrosion inhibitor.

The liquid and particles in admixture may initiate a cleaning action within fluid- carrying apparatus. The fluid-carrying apparatus may include a pump. Other features of this further aspect of the invention may be defined with reference to any one or more of the features and corresponding method steps as appropriate of the first to fourth aspects of the invention.

There will now be described, by way of example only, embodiments of the invention with reference to the following drawings, of which:

Figure 1 is a cross-sectional representation of a pipeline with a clean-up fluid being pumped though to remove loose solid particles from the pipeline according to an embodiment of the invention.

Figure 2 is a cross-sectional representation of a pipeline with a clean-up fluid being pumped though to remove solid residues formed inner walls of the pipeline according to a further embodiment; and

Figure 3 is a close up representation of different size sand particles of the cleanup fluid of Figure 2.

With reference firstly to Figure 1 , a fluid-carrying pipeline 10 is generally depicted. A clean-up fluid 12 introduced to the pipeline 10 is shown in Figure 1 in use whilst being delivered at pressure though the pipeline 10 in the direction of arrow 1 1 to remove loose solid particles 18 and clean the pipeline 10.

In this example, the clean up fluid 12 comprises water 14 (constituting a "liquid") and newspaper particles 16 (constituting "fibre particles") in admixture.

The newspaper particles 16 are dispersed in the water 14, and are present generally throughout its volume. In this case, the clean-up fluid is prepared from 1 % w/w of newspaper particles, and 99% w/w of water. The newspaper particles appear as "suspended" in the volume. The resulting distribution of newspaper particles allows loose solid particles 18 (constituting "additional particles"), which are lifted into the volume as the clean-up fluid is moved though the pipeline, to be suspended or carried along with the clean-up fluid, in the volume. The clean-up fluid 12 acts as a thick soup or "slurry" in the pipeline 10. However, its overall viscosity is low, and sufficiently so that the loose particles 18 are picked up, drawn and mixed into the volume of the fluid 12 as it is moved along the pipeline 10. Thus, the clean-up fluid 12 changes its composition and acquires further constituent particles as it progresses through the pipeline; the further particles 18 themselves and the newspaper particles 16 being in admixture in the water 14. The newspaper particles assist to carry or suspend the loose particles from the pipeline in the clean-up fluid.

In Figure 2, a pipeline 100 is shown generally with a clean-up fluid being pumped through in a similar manner to that described with reference to Figure 1 . In this example however, the clean-up fluid 1 12 is prepared in its initial constituency to comprise newspaper particles and additionally abrasive particles 122 in admixture in the volume of water 1 14. More specifically, the clean up fluid 1 12 is formed from a first volume comprising 99% w/w water 1 14 admixed with 1% w/w of newspaper particles 124 (identical to the clean-up fluid 12 described above), and a second volume of sand particles 122 (constituting the "abrasive particles") which is equal to the first volume.

The newspaper particles 1 16 assist to carry or suspend the sand particles 122 from the pipeline in the volume of water, and the clean-up fluid 1 12 as a whole acts as a slurry and functions in use in a similar manner as described in the Figure 1 example.

In addition, the clean-up fluid 1 12 in this example functions in use to scrape off unwanted residue or scale 126 coated or encrusted on an inner wall 120 of the pipeline 100. As the clean-up fluid 1 12 is pumped at pressure through the pipeline, the sand particles 122 scrape and abrade against the residue to remove it from the pipeline wall.

The scale or residue material that is removed from the pipeline wall is also mixed into the volume of water and carried through the pipeline in the volume along with the fluid. The solid loose particles acquired in the volume, along with the sand particles, and newspaper particles are again present in admixture in the volume of water.

With further reference to Figure 3, the sand particles 122 are shown in further detail. The particles have different sizes so that the composition can effectively clean the pits and dimples 130 formed in internal walls of the pipeline 120. This figure demonstrates that large sand particles 128 are not suitable for cleaning although they have a strong abrasive action themselves. Smaller abrasive particles 129 however can access smaller pits and dimples 130 to clean these more effectively.

The clean-up fluid as described in the present examples are prepared manually by measuring out appropriate amounts of the fibre particles, water and abrasive particles if required, locating these constituents together in a receptacle, and mixing these constituents by manual shaking or stirring. Of course, it will be appreciated that a mechanical arrangement could be used to automate these tasks and prepare sufficient quantities of the clean up fluid. The ingredients do not need to be added in any particular order.

In other embodiments, it will be understood that instead of water, an oil-based liquid is used. Further, it will be understood that other kinds of fibres or abrasive particles could be used in place of those described in the specific examples. In particular, it will be understood that although the examples describe the use of the cleanup fluid in connection with pipelines, it could equally be applied to clean other fluid- carrying apparatus, such as tanks, pumps, containers, or other apparatus.

In another example, the liquid and fibre particle admixture of Figure 1 includes a corrosion inhibitor in the liquid. The corrosion inhibitor has a "sticky" constituency allowing it to separate out from the fluid and adhere naturally to a surface of the pipeline when it comes into contact with the pipeline surface. Thus, as the fluid is pushed along the pipeline at a certain pressure such that the fluid makes contact with the sides a coating of protective corrosion inhibitor is applied evenly over the surface.

It will be appreciated that the corrosion inhibitor would typically be introduced to the fluid toward the end of a cleaning process, particularly after abrasives used to remove unwanted residues have been introduced and applied to the fluid. Thus, it will be appreciated more generally that the constituents of the fluids described herein may be introduced at different times as and when required for achieving particular cleaning or treatment effects.

In another example variant, a liquid and fibre particle admixture constituting the fluid 12, as referred to above with reference to Figure 1 , is used as a transport medium for carrying road aggregates from one location to another. In this example, a storage tank containing aggregate materials is provided at a roadside location, and the admixture is delivered to the tank and mixes with the aggregate materials so that the materials are carried in the volume of the liquid. The fluid including the aggregate is then pumped, to move the aggregates typically more readily than previously possible, from the tank to the road where the aggregate material can be evened out to form a road bed.

The present invention provides a number of advantages. The clean-up fluid having fibre particles and water in admixture provides a slurry-like admixture capable of picking up and carrying loose solids along the pipeline to remove them and clean the pipeline. In addition, providing the clean-up fluid with abrasive particles which are carried in a volume of the fluid and dispersed in the volume, allows scale built up on the inside surfaces of the pipeline to be scraped off, and also to be carried away in the volume to remove it from the pipeline.

Further, the unwanted particles and residues are readily mixed into and are dispersed in the volume of the fluid due to its low viscosity (as facilitated by the use of water), thus the clean-up fluid is an effective transport medium for particles and efficient at moving dirt away from the side surfaces of the pipeline, and away from the front of the flow. In turn, this helps to clean the pipeline in a single pumping process, potentially using a single batch of clean-up fluid, and to avoid blockages. In addition, components of the clean-up fluid are readily available and the technique is therefore cost effective, such that long-distance pipelines can be cleaned.

In examples where the fluid carrying apparatus includes a pump, the clean-up fluid described above is particularly effective at carrying with it solid particles so that they are prevented from settling out in the pump, thereby avoiding pump seizure.

In other examples, the clean-up fluid includes a solvent which helps to remove solids from the pipe surface. The solids which are removed are suspended in the fluid due to the presence of the fibre particles, and the fluid thereby forms a "solvent" slurry. This slurry is advantageous in that it ensures a relatively even application of the solvent to the pipe surface, decreases the amount and volume of the expensive solvent used, eases recovery of the solvent compared with prior art traditional solvent techniques.

Yet further, the ability of the clean-up fluid to support abrasive particles of various different sizes, along with its general flowability as described above, allows pits, creases, corners, dimples and areas around other irregularities in the fluid-carrying apparatus, to be effectively accessed, cleaned, and treated.

Various improvements and modifications may be made within the scope of the invention herein described. In particular, it will be appreciated that in other embodiments the water-to-fibre particle (e.g., newspaper particle) ratios indicated could differ from the specific example ratios referred to herein. For example, the clean up fluid may contain

5% w/w newspaper particles and 95% water. In other cases, the clean up fluid may contain 50% w/w of newspaper particles. The fibre-water composition used for a particular application will typically be dependent on the weight, size and suspendability of fibres selected, and the viscosity of fluid required.