WO2011064563A1

WO2011064563A1 - Method of handling waste material

Info

Publication number: WO2011064563A1
Application number: PCT/GB2010/051834
Authority: WO
Inventors: Patricia May Reid; Albert Fleming
Original assignee: Scotoil Services Limited
Priority date: 2009-11-30
Filing date: 2010-11-02
Publication date: 2011-06-03
Also published as: GB0920907D0

Abstract

A method of handling waste material is disclosed, the method comprising mixing a settable resin material with the waste material and allowing the settable resin material to change its configuration from a first fluid configuration to a second solid configuration, thereby embedding the waste material within the solid resin material to form a solid block so that the waste material is immobilised in the solid block of set resin material. The waste material typically comprises scale from one or more oil and/or gas wells, and also typically comprises naturally occurring radioactive material (NORM). The method allows the immobilising of contaminating substances in the waste material to render it safe, and typically resistant to leaching from the set resin material.

Description

METHOD OF HANDLING WASTE MATERIAL

This invention relates to a method of handling of material, particularly to the handling of waste material such as scale generated by or in an oil or gas well, and is especially applicable to the handling of waste material that is contaminated e.g. by naturally occurring radioactive material, although the method is generally applicable for the handling of other materials for disposal. Oil and gas wells generate valuable hydrocarbons, but also generate waste materials that need to be treated and disposed of. For example, during the drilling phase of the well, drill cuttings are generated, and during the production phase of the well, scale is generated. Scale typically builds up within well conduits and other equipment as a result of various factors including mixing of incompatible fluids, pressure changes, temperature changes, the presence of impurities or additives in downhole fluids, changes in their flow rates, or changes in pH or other qualities. Scale problems especially arise where hydrophilic fluids such as water are injected or otherwise exposed to hydrocarbon-containing production fluids.

Scale arises frequently in wells where water is injected into the formation. Injection of seawater into the reservoir is a common technique used to maintain production pressure during the life of the well. Mixing of the injected water with reservoir formation fluids often has the effect of altering the relative concentrations of certain ions such as barium and sulphate in the combined produced fluids leading to a super saturated condition, which often increases the tendency to form scale in the conduits guiding the produced fluids from the well. Under conditions of reducing temperature and pressure, this ion imbalance will often result in the deposit of salts and scales on the conduits and other equipment.

Scale generated within oil and gas wells is typically relatively insoluble, and can be un-reactive to solvents, acids and alkalis, and can therefore be resistant to chemical clean-up methods. Scale build-up over time gradually impacts on the volume of produced fluids and on oil production. Scale therefore has to be removed from the well equipment, for example, by blasting with high pressure fluids and/or abrasive materials to physically dislodge the scale from the equipment on which it is deposited.

This formation of scale on oil well equipment often has the effect of concentrating minute quantities of naturally occurring radioactive material (NORM), such as radioactive ions, within the scale that are naturally present at low levels in the produced fluids. Scale built up in this way will frequently contain high enough levels of NORM to require its classification as a radioactive substance, which can have implications for its removal and disposal. According to the present invention there is provided a method of handling waste material, the method comprising

- providing a settable resin material that is adapted to change from a first fluid configuration to a second solid configuration;

- mixing the settable resin material with the waste material when the settable resin material is in the first fluid configuration;

- allowing the settable resin material to change its configuration from the first fluid configuration to the second solid configuration, thereby embedding the waste material within the solid resin material to form a solid block comprising the waste material and the resin material; - wherein the solid block of set resin material immobilises the waste material.

Typically the method is applied to waste material from oil and/or gas wells, although waste material from other sources can be treated with the method.

Typically the material being treated is particulate in nature, or is ground up before mixing with the settable resin material. However, single large pieces of waste or contaminated equipment can optionally be treated as whole pieces. This allows the treatment of whole valves or tubes etc which have e.g. radioactive contamination engrained into or otherwise associated with the item (e.g. engrained into a surface of the item).

Certain embodiments of the invention are therefore useful in the treatment of whole contaminated items and parts thereof from the oil and gas industry, nuclear industry, and any activity that generates NORM waste e.g. the china clay industry and the zircon industry.

Typically the waste material comprises NORM.

Typically the material is scale, although other waste material, especially from oil and gas wells, can be treated using the method of the invention.

Typically the waste material can have a particle size of between 0 and 2mm, 2-3mm, 3-4mm, 4-5mm, 5-10mm, and above, although particles of the order of centimetres (e.g. 2.5 cm) are easily treatable by the method, as are larger particles. The waste material can be ground or otherwise reduced in size to within a typical range of 100-250 microns as an early step in the treatment, before the configuration change of the settable resin material, and typically before the mixing of the waste with the settable resin material, although the settable resin material can optionally be ground along with the waste prior to the configuration change, but typically after mixing. Optionally the settable resin material can comprise a cross-linking agent.

The settable resin material can optionally include a catalyst added before or during the step of the configuration change, to accelerate or initiate the configuration change in the settable resin material. Optionally the settable resin material does not undergo the configuration change to the set configuration in the absence of the catalyst. Typically the combination of the catalyst and the settable resin material is chosen such that the time between initiation and the completion of the configuration change in the settable resin material is relatively short, so that setting occurs as soon as possible after mixing, to minimise the extent to which the waste material settles out of dispersion in the settable resin material. In certain advantageous embodiments of the invention, the waste material is maintained away from the periphery of the solid block, so as to

encapsulate the waste material within the block as much as possible. For example, in some embodiments of the invention, a resin layer can be pre- lined in a drum or mould and allowed to set leaving a recess spaced away from the wall of the mould before the waste material is added.

In certain embodiments, the waste and the settable resin material are stirred to mix them, but typically the stirring or other mixing step is low impact, and does not entrain air within the mixture. It will be appreciated that the speed of stirring and the extent of agitation during this optional step will be dependent on the viscosity, particle size and other

characteristics of the materials being mixed and their relative quantities, and that it is not appropriate to define the limits of the speed or the geometry of the mixer, but that it is adequate to define these parameters with respect to the effect of the air bubbles entrained in the mixture.

Typically, a mixture of waste and settable resin material is mixed at a speed that does not entrain or generate bubbles within the mixture of settable resin material and waste.

Typically the settable resin material and the waste are poured into a mould after mixing together, but before setting of the settable resin material. The mould is typically a cuboidal shape, with a square or rectangular cross section. The mould can optionally incorporate protrusions to form recesses in the block, e.g. in one or more faces of the block, typically on opposite faces. Typically the mixture is poured into cuboidal moulds, of typical size of 200-10001. Optionally, moulds can have a typical volume of 10, 20, 50 or 1001.

The block can typically be formed as a building block, and can be used in construction after the settable resin material has set. The invention also provides a block for construction, the block comprising a waste material immobilised in a settable resin material and typically set in the shape of a regular block.

Typically the viscosity of the settable material and of the mixture of the waste material and the settable resin material is relatively high, to maintain the dispersed particles of waste materials in suspension within the settable resin material when the settable resin material is in the fluid phase, prior to setting. Advantageously, this means that particles of the waste material do not sink to the bottom or other peripheral areas of the block.

In some embodiments using resins as the settable agents, the settable resin material can comprise a thermosetting resin. A suitable thermosetting resin is polyester resin such as CRYSTIC-2-8500PA manufactured by Scott Bader Company Limited.

Suitable resins are generally hydrophilic, and unsaturated polyester resins are particularly suitable.

In some embodiments of the invention, the settable material can comprise a monomer or short chain polymer capable of forming a regular matrix structure throughout the block when set. A suitable resin in this regard is epoxy resin.

Vinylester resin is a useful alternative to polyester and epoxy materials in matrix or composite materials, and has a particularly low resin viscosity. Resins are especially useful for settable materials in embodiments of the present invention, as they can exhibit superior non-leachable properties than other settable materials, as the resin sets into a non-porous block that effectively retains more of the activity of the waste and restricts the amount of active waste that can leach from the set block. Resins with low molecular weight (e.g. between 80 and 300) can be especially useful, such as SYNOLITE 6060-P-1 (manufactured by DSM composite resins AG) because these can typically form tighter matrices throughout the block that can restrict leaching of the waste material. Resins can also exhibit a more uniform chemical composition than other settable materials and can result in blocks that are mechanically stronger, and that are more resistant to chemical reactions. Resin blocks are typically also more likely to retain their structural integrity and can accommodate a much wide range of filler ratios without affecting the resultant block's integrity. The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one embodiment can typically be combined alone or together with other features in different embodiments of the invention.

Various embodiments and aspects of the invention will now be described in detail. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, which illustrates a number of exemplary embodiments and aspects and implementations. The invention is also capable of other and different embodiments and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the examples are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as

"including", "comprising", "having", "containing" or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered

synonymous with the terms "including" or "containing" and is not intended to be solely an indication that the features following that term are exhaustive.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention. In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of", "consisting", "selected from the group of consisting of or "is" preceding the recitation of the composition, element or group of elements and vice versa.

All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein including (without limitations) components of the apparatus to collect cuttings are understood to include plural forms thereof and vice versa.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying examples.

Materials and methods

The contaminated waste used in the following examples was NORM scale. The NORM scale material typically comprises fragments of scale dislodged from pipelines and other oil well installations and equipment (for example, valves, connectors, pipes and filters, pumps, separators and subsea or topsides manifolds such as Christmas trees) that have been decontaminated during normal maintenance and cleaning operations. The fragments of scale material that are dislodged by the high pressure washing are typically of various different sizes and although treatment of different sizes of NORM scale fragments is entirely possible, the fragments are typically sorted into similar sizes, or optionally ground by passing the material over a 250 micron sieve, washing oversized material into a ball mill and grinding the oversized material until it passes through the sieve. The ball mill used in some examples is about 3m long, with a diameter of 0.914m and is run at around 20 rpm. The standard grinding time is 10-12 hours. This typically yields a sand-like material which when dried can flow like sand. The average useful particle size distribution for the ground NORM scale is around 50-150 microns, with a typical diameter of around 100 microns. The radioactivity of the NORM scale can vary from sample to sample in accordance with the prevailing levels of NORM in the environment from which the scale is obtained, but in typical sample, we achieve successful treatment of NORM scale having an initial activity of up to 10-200 Becquerels per gram.

Different resins can be used for the settable material. Methods of mixing resins are well known and need not be recited in detail. Resins are typically added to NORM scale that has been ground as described above and mixed until the NORM scale has been evenly dispersed throughout the resin. The objective is to obtain a mixture that had few gradients in local concentrations of NORM scale, so it is an advantage if setting occurs quickly after mixing. Mixing should not be so vigorous as to create excessive amounts of bubbles in the mixture, nor should setting occur so quickly that bubbles have no opportunity to dissipate. Bubbles are advantageously avoided in the set mixture. Typically this is achieved by using quick setting resins and mixing slowly e.g. 3-5 rpm for 10-20 minutes in e.g. a 5I drum with a large plough shaped rotary beater that covers substantially a whole circumference of the drum. When mixed but still fluid, the mixture is poured into containers and left to set. It is desirable that the viscosity of the mixture at this stage is relatively high, so that minimal settling of the scale occurs before setting. Typically the containers can be cuboidal, and we found that rectangular tubs with dimensions of 30x20x10cm were suitable, and allowed fairly easy handing of the blocks when set. The tubs can optionally be formed with inwardly pointing protrusions in the walls, which protrude into the resin and scale mixture during setting, and form recesses in the set blocks. Typically the protrusions can be formed in at least one of the faces of the tubs. This protrusion can create a recess or "frog" typically for retaining a bonding agent such as cement or the like if the block is to be used in construction. The tubs can clearly be of any dimensions, and the dimensions of bricks or blocks used in construction can be adopted, enabling the production of blocks that can optionally be used for construction after treatment.

Typical resins used as settable materials are polyester, vinylester and epoxy resins from Scott Bader Company Limited, Wollaston,

Wellingborough, UK, DSM Composite Resins AG, Stettemerstrasse 28, Switzerland, and Gurit (UK) Ltd, Newport, UK. Catalysts or curing agents used to initiate or accelerate the setting of the resins were typically MEKP (methyl ethyl ketone peroxide, also known as butanone peroxide), or benzoyl peroxide for the polyester and vinylester, from Scott Bader Company Limited, Wollaston, Wellingborough, UK, DSM Composite Resins AG, Stettemerstrasse 28, Switzerland, and Gurit (UK) Ltd,

Newport, UK. Resins are typically mixed with ground NORM scale as described above, then mixed with catalysts and then poured into containers such as the tubs mentioned above, and left to set.

The process of curing most resins using a catalyst is typically an exothermic process, which if uncontrolled can damage the resin or the block. Typically the ratios by weight of resin:scale are maintained relatively low, for example, within the range of 30:70 and 50:50 and typically relatively more scale is added to a mixture than resin. This tends to result in more controllable exothermic reactions than if the amount of resin is dominant, and also allows addition of higher volumes of catalyst to enable faster setting (and therefore less settling of the scale) without excessive heat generation. This also allows the advantage of a high ratio of waste material that can be encapsulated in a relatively small amount of resin, enabling economic as well as technical advantages. However, higher ratios of the resin to scale (e.g. above 50:50 such as 60:40, 70:30, 80:20 or more) can be used in certain embodiments.

Typically the amount of catalyst added is a balance between adding sufficient catalyst to solidify the block before the even dispersion of NORM scale can settle to the bottom of the container, but not so much that setting begins before adequate mixing, and/or the setting mixture generates excessive heat sufficient to damage the block. Typically catalyst is added to the mixture after mixing the scale and settable material together, and just before pouring into the moulds. Example 1

200ml of commercially available Epoxy resin (from Gurit (UK) Ltd,

Newport, UK) with a measured weight of 255g was combined with 20% NORM scale by weight (51 g) bringing the total weight of the mixture to 306g. The NORM-containing scale was obtained from pipeline washout and ground as described above. The resin and scale was mixed by hand using a spatula stirring the mixture until all the scale was encapsulated within the epoxy for approximately 1 -2 minutes and mixture was

heterogeneous and fluid. SP 106 Epoxy resin using 0.1 -1 .0% of a slow hardener was added to the resin at a ratio of 5:1 by volume of resin, equating to a total addition of 33ml of hardener. The epoxy/scale mix was combined with the hardener, again using a spatula, and hand mixed for a further 1 -2 minutes again insuring that the mixture was fluid and evenly mixed, upon which the mix was transferred to a rectangular mould of dimensions 210x1 10x65mm for curing. The mould had a protrusion on the base creating a recess in the moulded block. The mix had a relatively low viscosity, and poured easily. After 15-20 minutes following addition of the hardener, an exothermic reaction could be detected as temperature of the mix was increasing rapidly. The mix then started reacting violently with gas emissions visible from top of the mould. The mixture swelled in the mould while continuing to rise in temperature and then set rapidly. Total setting time for epoxy resin block was 35-45 minutes.

Due to resin expansion the block proved difficult to extract from the pot. The scale had been encapsulated adequately, but had noticeably settled at the bottom of the pot with the resin giving the sample a glass like finish with a fractured like appearance to expansion areas.

Example 2

200ml of commercially available vinylester resin mix (obtained from DSM Composite Resins AG, Stettemerstrasse 28, Switzerland, with a measured weight of 241 g was poured into a 500ml mixing vessel, and 20% (48g ) NORM scale was added by weight bringing total weight of mixture to 289g. The resin and scale was combined using a spatula as described above. 1 % by volume of resin of Methyl Ethane Ketone Peroxide (MEKP) was added, equating to a total addition of 2ml of catalyst. The vinylester /scale mix was combined with the catalyst, again using a spatula, and hand mixed for a further 1 -2 minutes until the mixture was fluid and

heterogeneous, and the mix was transferred to a container as described above for curing. The mixture had low viscosity, and poured easily.

After 60-75 minutes a slower exothermic reaction could be detected as temperature of the mix was increasing gradually. The temperature steadily increased until curing was complete. Total setting time for the vinylester resin block was 80-90 minutes.

After setting, it was observed that the resin had set without fractures, but the NORM scale was not fully encapsulated within the resin giving the block a poor finish with pit holes visible.

Example 3

200ml of polyester resin mix (obtained from DSM Composite Resins AG, Stettemerstrasse 28) was with a measured weight of 251 g was combined with 20% (50g) NORM scale by weight was added bringing the total weight of the mixture to 301 g. The resin and scale were combined by hand as described for examples 1 and 2, and 1 % by volume (2ml) of resin of MEKP was mixed into the sample, which was poured into a container as previously described. The mixture was slightly thicker than previous examples, and had a higher viscosity.

After 35-45 minutes a moderately slow exothermic reaction could be detected as temperature of the mix was increasing gradually. The temperature steadily increased until curing was complete. Total setting time for the polyester resin block was 50-60 minutes.

After curing it was observed that the NORM scale was fully encapsulated within the resin and seemed to be evenly distributed throughout the block, giving the block a smooth consistent matt finish on its outer surfaces. The block easily fell out of the mould due to the resin shrinkage during curing.

Example 4

300ml (377g) of polyester resin (as used in example 3) was combined with 100ml volume (1 14g) of NORM scale, hand mixed at room temperature using a spatula, and stirring the mixture until all the scale was

encapsulated within the resin for approximately 1 -2 minutes and mixture was fluid. 1 % (3ml) by volume of resin of Methyl Ethane Ketone Peroxide (MEKP) was added, and the mixture was hand mixed for a further 1 -2 minutes ensuring that the mixture was fluid and that the various

components were fully and evenly dispersed, whereupon the mix was transferred to a container for curing.

The reaction was observed, and after 35-45 minutes an exothermic reaction could be detected as temperature of the mix was increasing. The temperature steadily increased until curing was complete. Total setting time for epoxy resin block was 50-60 minutes.

After curing it was observed that the NORM scale was fully encapsulated within the resin and seemed evenly distributed giving the block a smooth consistent matt finish on its outer surface. The block easily fell out of the mould due to the resin shrinkage during curing. Example 5

Example 4 was repeated, using equal 200ml volumes of polyester resin (251 g) and NORM scale (228g), but after 35-45 minutes no exothermic reaction could be detected, so a further 1 % of MEKP catalyst was added to the mixture and using a spatula, hand mixed for a further 1 -2 minutes again ensuring that the mixture was fluid and evenly mixed.

20-30 mins following addition of the second batch of catalyst, an exothermic reaction could be detected as temperature of the mix was increasing. The temperature steadily increased until curing was complete. Total setting time for the polyester resin block was 70-80 minutes. The total catalyst added was 2% of the resin volume. After curing it was observed that the NORM scale was fully encapsulated within the resin and seemed to be evenly distributed giving the block a smooth consistent matt finish on its outer surface. The block easily fell out of the mould due to the resin shrinkage during curing. Example 6

Example 4 was repeated again, but using 100ml of polyester resin (126g) and 200ml volumes of NORM scale (228g). The mixture had a higher viscosity as a result of the increased ratio of resin to scale. 35-45 mins after addition of the catalyst and pouring into the mould, no exothermic reaction could be detected, so a further 1 % (1 ml) of MEKP catalyst was added and using a spatula, hand mixed for a further 1 -2 minutes ensuring that the mixture was fluid and evenly mixed. After 20-30 minutes an exothermic reaction could be detected as temperature of the mix was increasing. The temperature steadily increased until curing was complete. Total setting time for the polyester resin block was 70-80 minutes. The total catalyst added was 2% of resin volume.

After curing it was observed that the NORM scale was fully encapsulated within the resin with an even distribution, and a smooth consistent matt surface finish. The block easily fell out of the mould due to the resin shrinkage during curing.

Example 7

Example 5 was repeated, but using 100ml of polyester resin (126g) and 300ml (342g) quantities of NORM scale.

No exothermic reaction was detected within 45 mins after pouring, and a further 1 % (1 ml) of MEKP catalyst was added and using a spatula, hand mixed for a further 1 -2 minutes. After 20-30 minutes no exothermic reaction could be detected, and a further 1 % (1 ml) of MEKP catalyst was added and using a spatula, hand mixed for a further 1 -2 minutes, again ensuring that the mixture was fluid and evenly mixed. 20-30 mins following mixing, an exothermic reaction could be detected as temperature of the mix was increasing. The temperature steadily increased until curing was complete. Total setting time for the resin block was 1 15-125 minutes. The total catalyst added was 3% of resin volume. The mixture had a high viscosity, and poured slowly.

After curing it was observed that the NORM scale was fully encapsulated within the resin and seemed to be evenly distributed giving the block a smooth consistent matt surface finish, although a small amount of pits or bubbles could be seen on the surface. The block easily fell out of the mould due to the resin shrinkage during curing. Results

Results of examples 1 -7 are summarised in table 1 . Using the same mixing and measuring process for each, the polyester resin visually gave the best results for encapsulating the scale into a solid block, however all resins were capable of holding 20% of scale by weight. The vinylester gave a porous surface finish but scale was evenly distributed throughout. The epoxy gave a strongest reaction using this mixing process but had the best surface finish although settling of the scale was evident at the bottom of the mould.

The increased ratio of scale to resin allowed the advantage of controlling the strong exothermal reaction of the catalyst and resin, possibly allowing higher levels of catalyst to be used to speed up the reaction to prevent settling, without excessive exothermal reactions damaging the block.

Leachate tests 10cm x 5cm x 2cm blocks are removed from the mould, cured for 28 days and leachate tested typically by immersion in a sealed tank containing around 25-301 of water, which is typically stirred continuously and sampled monthly over a period of 6 months by withdrawing samples of up to 1000 ml. Samples of the water taken from the tank can be analysed for the presence of radionuclides that have leached from the block. Inevitably there will be loosely attached scale at the surface of the block which will leach quickly, and most soluble salts will leach from the block within the first couple of months. After this initial period of surface leaching the activity in the sampled water gives a more accurate indication of the extent to which the contaminated NORM scale is immobilised in the impervious resin block. Samples of water are typically assessed for radioactive label using an HPGe (High-Purity Germanium) Coaxial Low Energy Photon Gamma Spectrometer to collect gamma ray emissions from the sampled water using a scintillation counter (HPGe). In the Gamma Spectrometer, a multichannel analyzer separates the pulses based on pulse height, and the resulting data is used in known methodology to produce a gamma energy spectrum for each block, which provides an indication of the identity and activity of gamma emitters present in the source. The gamma spectrum is characteristic of the gamma-emitting nuclides. Since each radioactive material emits gammas of certain energy levels, each pulse height corresponds to a different type of atom.

Activity tests A series of further examples were run to determine the radioactivity in the treated samples.

Examples 8-14 Resin was combined with NORM scale in the volumes shown in table 2 below, and was hand mixed at room temperature using a spatula for approximately 1 -2 minutes. Catalyst was added, and the mixture was hand mixed for a further 1 -2 minutes ensuring that the mixture was fluid and that the various components were fully and evenly dispersed, whereupon the mix was transferred to a container for curing.

After a period of time (usually 30-45 mins) an exothermic reaction was detected as indicated by the increasing temperature of the mix. The temperature steadily increased until curing was complete. Total setting time for the resin block is shown in table 2. All the blocks used in examples 8-14 had an even dispersion of the NORM scale fully encapsulated within the resin giving all the blocks a smooth consistent matt finish on their outer surfaces.

The radioactivity of each of the blocks was then measured by inserting each block into a Gamma Spectrometer as described above in relation to the leachate tests. The low activities of the samples set out in table 2 typically remain immobilised within the blocks after stabilisation of the initial surface leaching phase.

Modifications and improvements can be incorporated without departing from the scope of the invention.

Table 2 Activity of sample blocks from examples 8-14

Settin %

Example Resin/ g Resin Scale Catalyst NORM Radioactivity number Cement Time (g) (g) % SCALE (Becquerels per gram)

Radium- Actinium - Lead - 226 228 210

8 0 0 50 0 100 0.97 0.21 7.64

2%

9 Polyester 40 10 MEKP 20 0.47 <0.05 4.25

2%

10 Polyester 30 20 MEKP 40 0.26 0.06 2.25

2%

1 1 Polyester 25 25 MEKP 50 0.19 <0.05 1.99

2%

12 Polyester 20 30 MEKP 60 0.58 0.15 4.08

2%

13 Vinylester 40 10 MEKP 20 0.14 0.1 1.68

2%

14 Epoxy 40 10 TETA 20 0.46 0.1 1 4.23

Claims

Claims:

1 A method of handling waste material, the method comprising

- allowing the settable resin material to change its configuration from the first fluid configuration to the second solid configuration, thereby embedding the waste material within the solid resin material to form a solid block comprising the waste material and the resin material;

- wherein the solid block of set resin material immobilises the waste material.

2 A method of handling waste material as claimed in claim 1 , wherein the waste material is taken from one or more oil and/or gas wells.

3 A method of handling waste material as claimed in any preceding claim, wherein the waste material comprises naturally occurring

radioactive material (NORM).

4 A method as claimed in claim 3 wherein the NORM is concentrated in the waste material prior to the treatment of the waste material.

5 A method as claimed in any preceding claim, wherein the waste material comprises scale.

6 A method as claimed in any preceding claim, wherein the resin material sets in response to exposure to a catalyst added to accelerate or initiate the configuration change in the resin material, and wherein the combination of the catalyst and the resin material is chosen such that the resin sets before the waste material settles out of dispersion in the resin material. 7 A method as claimed in any preceding claim wherein the waste material is maintained away from the periphery of the solid block during setting of the resin material.

8 A method as claimed in any preceding claim, wherein the resin material is mixed with the waste material at a speed that does not entrain or generate bubbles within the resin material.

9 A method as claimed in any preceding claim wherein the resin material and the waste are disposed in a mould after mixing together, but before setting of the resin material, wherein the mould has a cuboidal shape, with a square or rectangular cross section, and wherein the mould incorporates protrusions to form at least one recess in a face of the block.

10 A method of handling waste material as claimed in any preceding claim, wherein the material being treated is particulate.

1 1 A method of handling waste material as claimed in claim 10, wherein the waste material is ground into particles before setting of the resin material.

12 A method as claimed in claim 1 1 wherein the material is sorted into particles having a size range of 100-250um before the mixing of the waste with the resin material. 13 A method as claimed in any preceding claim, wherein the viscosity of the settable material and of the mixture of the waste material and the settable material is maintained at a level sufficient to maintain the dispersed particles of waste materials in suspension within the settable material when the settable material is in the fluid phase, prior to setting.

14 A method as claimed in any one of claims 1 -9 wherein the waste material comprises a contaminated piece of equipment which is embedded in the resin without being ground into particles.

15 A method as claimed in any preceding claim, wherein the settable resin material has a molecular weight within the range of 80 to 300.

16 A method as claimed in any preceding claim, wherein the weight ratio of resin:scale within a block is in a range of 30:70 to 50:50.

17 A block for construction, the block comprising a waste material immobilised in a settable resin material.