Method of limiting permeability of a matrix to limit liquid and / or gas inflow

Abstract

A method of limiting or reducing permeability of a matrix to liquid and / or gas inflow is described. The method includes limiting inflow of water, liquid and / or gas into passages such as cavities, fissures, voids and the like, encountered in formations such as geological formations though can be used to form barriers to water, liquid or gas flow through a matrix. The method includes steps of measuring one or more parameters relating to the matrix and selecting one or more components of a multi-component sealing composition with reference to the measured parameters. The selected components are introduced into the matrix where it is set or coagulated in a non-exothermic or low exothermic process to form a seal barrier. Also disclosed is a sealing composition comprising a coagulable polymer emulsion or colloid contactable with at least one selected additive which interacts with the polymer emulsion or colloid to form a coagulated mass for forming a sealing barrier in a non-exothermic or low exothermic setting process in which the polymer emulsion or colloid contains, prior to purposeful coagulation due to interaction with the selected additive, particles having a size distribution smaller than for Portland cement.

Description

METHOD OF LIMITING PERMEABILITY OF A MATRIX TO LIMIT LIQUID AND / OR GAS INFLOW FIELD OF THE INVENTION The present invention relates to a method of limiting or reducing 5 permeability of a matrix to liquid and / or gas inflow, including limiting inflow into passages such as cavities, fissures, voids, open features and pore spaces encountered in formations such as geological formations. The method may also be applied to sealing of passages in other situations such as construction, for example in tunnels, or forming sealing barriers to prevent fluid flow in other 10 situations. The method may also be used to form barriers to liquid or gas flow within a permeable matrix. BACKGROUND TO THE INVENTION Methods of attempting to substantially seal or otherwise reduce the permeability of a matrix such as concrete, rock or soil are known. For example, 15 regular cement based suspension grouts can be introduced into voids, opens spaces and pore spaces around a mine shaft in order to attempt to seal fissures or reduce the permeability of unconsolidated sand or soil around the shaft, thereby limiting liquid inflow into the shaft Typically, a volume of grout or sealing composition product is transported 20 to the site to be treated and applied to the passage or passages requiring sealing to prevent water inflow. Application typically involves pumping of grout to the passage or passages. Sealing composition which is generally premixed prior to delivery of the site often provides less than satisfactory results in terms of preventing or reducing water inflow. For example, injection or introduction of a 2s cement based grout, known to have suitable properties in sealing passages, can cause hydrofracturing if applied to an unconsolidated matrix such as sand or sandstone. This can create seams of grout within the matrix, leaving sections of unconsolidated matrix on either side of the created seams. Such an application has minimal impact on reducing the ability for water to pass through the matrix 30 and hence into a shaft that has been sunk through the matrix. There is also difficulty in use of premixed grouts in that setting time cannot be controlled or varied either at all or with any reliable degree of accuracy. This is CA 3005556 2018-05-22 2 detrimental in that known premixed grouts are generally capable only of providing a "one size fits all" sealing solution. Since there is such a wide range of conditions that can be experienced when seeking to limit permeability of a matrix so as to limit liquid inflow, a 'one size' approach to all types of inflow problems is 5 inherently unsuitable. Traditional and pre-mixed cement and bitumen based grouts can additionally fail to adequately penetrate the passage or passages to be sealed. At least part of this failure can be attributed to the sealing composition simply failing to penetrate through the matrix to a required depth, for example where 1 o passages are of small dimension. For example, cement sealants are suitable for sealing passages having dimension greater than 160 microns whereas leaks or slow seepage may occur through cracks or fissures having significantly smaller dimensions. Rate of setting of the sealing composition can also affect whether or not the sealing composition is able to adequately prevent or practically reduce 15 water inflow. For example, it is desirable when applying a grout to reduce permeability in a sand formation, that the grout can be able to permeate a suitable distance through the formation prior to setting. If setting occurs prematurely, the grout is unable to adequately penetrate the matrix and create sufficient adhesion of 20 particles in the matrix to form an effective seal to water inflow. Applicant's earlier patent AU 739427 utilises a composition which includes latex and wherein viscosity of the composition is increased with rate of shear as the composition penetrates into the passage. Whilst this can assist in controlling excessive grout spread within the matrix and help to ensure that the bulk of the 25 grout remains within the target zone of the matrix, it still presents a somewhat generic approach to controlling set times of the grout once introduced into the passage. Further, set time of the grout cannot be regulated or varied with any degree of reliability to accommodate, for example, specific needs or requirements of the application at hand. 30 Another known method of preventing or limiting water inflow into an excavation in a ground formation is the method of ground freezing. This method is often the preferred method of ground support in vertical shaft construction. The method utilises water in situ in pore spaces of the ground formation and freezes it so that the water acts as a bonding agent, fusing together particles of soil or rock CA 3005556 2018-05-22 3 to create a solid mass with substantial impermeability Whilst the ground is frozen, a concrete liner is usually constructed about the path of the shaft. Proper execution of this method, particularly at depth, is complex and requires substantial capital outlay. After freezing and construction of the concrete 5 liner and before the ground is permitted to thaw, absolute water tightness must be established in the concrete liner. If it is not water tight, seepage can dissolve matrix from behind the shaft lining, increasing the leakage path and ultimately flooding the mine. Salt mines in particular are known to be susceptible to this due to the salt dissolving and mines have been lost in this manner. 10 These aforementioned problems are also applicable and indeed may be more pronounced if it is desired to limit or reduce permeability of a matrix so as to reduce or limit flow of gas. For example, in a hydraulic fracturing (hydrofracturing) operation to extract hydrocarbon gas reserves from a reservoir, it may be desirable to limit the permeability of sections of ground surrounding the wellbore 15 so as to prevent undesirable or disadvantageous flow of gas. It may also be desired to seal passages or pore spaces in a ground formation to seal in hydrocarbon or other gases in oil and gas seams. Known methodologies for reducing permeability of the ground to prevent or limit this have thus far been found to be largely ineffective or unreliable. In view of the fact that there is ever 20 increasing reliance on methods such as hydrofracturing, there is an increased need for capacity to reliably contain gas within a formation and prevent ingress into inappropriate regions. It is therefore an object of the present invention to provide a method of limiting or reducing permeability of a matrix to limit or reduce liquid and / or gas 25 inflow, including limiting or reducing gas and / or liquid inflow within a passage in the matrix that reduces the aforementioned problems experienced with prior art methods. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a 30 method of limiting or reducing liquid and / or gas inflow through a permeable matrix, such as a geological formation, comprising measuring one or more parameters relating to said matrix and selecting one or more components of a multi-component sealing composition based on a polymer emulsion or colloid with reference to said measured parameters and introducing said components of said CA 3005556 2018-05-22 4 sealing composition into said permeable matrix where it is set or coagulated in a non-exothermic or low exothermic setting process to form a seal barrier. The method is particularly suited to limiting or reducing liquid inflow through a matrix Such liquids may for example include water, oil, solvents and other chemicals. 5 The method may also be used to prevent gas inflow through a matrix or to confine gas to a particular reservoir. Low or non-exothermic setting has potential benefits such as avoidance of premature setting, lower shrinkage and lower mechanical stresses in comparison to exothermic setting systems, for example as encountered with epoxy resins and 10 some polyurethane formulations. In addition, a concern with exothermic setting processes that cause non-linear polymer mass temperature increase and potential non-uniform curing can be addressed. The result is a seal barrier with more reliable barrier qualities. The sealing composition desirably includes a coagulable polymer emulsion 15 or colloid which is contacted with at least one selected additive which interacts with the polymer emulsion or colloid to form a sealing composition barrier to reduce or block liquid or gas flow through the matrix. The polymer emulsion or colloid desirably also contains, prior to purposeful coagulation, due to interaction with the at least one additive, particles having a size distribution smaller than for 20 Portland cement. In another embodiment, the present invention provides a sealing composition comprising a coagulable polymer emulsion or colloid contactable with at least one selected additive which interacts with said polymer emulsion or colloid to form a coagulated mass for forming a sealing barrier in a non-exothermic or low exothermic setting process, wherein said polymer 25 emulsion or colloid contains, prior to purposeful coagulation due to interaction with said at least one selected additive, particles having a size distribution smaller than for Portland cement. The particles include polymer particles and any additive particles present. Portland cement has a typical particle size distribution lying between 5 and 30 30 microns The desired polymer emulsion or colloid has a substantially smaller particle size distribution with average particle size in one embodiment being less than 5 microns, preferably less than 2 microns, most preferably less than about 1 micron. The polymer emulsion or colloid may comprise a substantial proportion of particles with uniform particle size, for example at about 1 micron. Such CA 3005556 2018-05-22 5 particle size distribution eases pumpability of the polymer emulsion or colloid, which can be described as a grout component, even into voids of narrow dimension, including passages narrower than 160 microns, allowing pumping costs to be optimised for the sealing application. 5 In a preferred embodiment of the present invention, the sealing composition, or grout, comprises at least one latex-based component and one or more further selected additives. It is preferred that the latex is natural latex, preferably of purity greater than 50 wt%, more preferably 60 wt% natural latex. In a particularly preferred embodiment, the sealing composition comprises a iatex 10 emulsion or colloid and lauric acid or a laurate compound; and at least one further selected additive. The at least one further additive is selected at least partially by reference to measured parameters of the site to be treated. However, latex based sealing compositions - despite advantages due to non-exothermic or low exothermic setting as described above - may not be 15 suitable for some situations. For example, in colder regions, where formation temperatures can be below -5°C, a non-latex sealing composition may be selected. In particular, it is desirable to select a non-latex sealing composition if the temperature of the ground or the surrounding site will be -12°C or less. It will be noted that this method is not confined to any particular species of sealing 20 composition. Latex sealing compositions may freeze at such low temperatures and this is undesirable. Steps can be taken to maintain latex sealing compositions above freezing temperature, for example by heating or adding freezing point depressants. The polymer emulsion or colloid desirably includes coagulation or setting 25 inhibitors to prevent setting of the composition under shear and promote flow into and permeation of the site to be treated prior to initiation of setting to form the sealing barrier. The desirable small particle size distribution of the polymer emulsion or colloid and any additives assists with flow and permeation into the matrix to be treated including very narrow passages that might not even be 30 subject to water leakage prior to sealing of larger passages, providing a significant advantage over cement Non-limiting examples of inhibitor additives are surfactants, such as cationic surfactants. Surfactants can prevent flocculation of latex upon introduction into the passage. At sites where water present in the CA 3005556 2018-05-22 6 passage has high salt concentrations, that is, the water is substantially brine, the water in the passage can be treated with an inhibitor additive to prevent early coagulation or setting of the surface composition in the passage. A non-limiting example of such an inhibitor additive is the proprietary product KT, which contains 5 a mixture of sodium phosphates and which when introduced to the passage as a solution, acts to prevent or slow down coagulation or setting of the sealing composition in the passage. The selected additive may also include a coagulation activator or curing agent to initiate or promote setting. Such activator or curing agent initiates a non- 10 exothermic or low-exothermic setting process. Non-limiting examples of these additives are alkaline compounds; plasticisers, carboxylic acids, borates, silicates, hydroxides as well as metal salts thereof. Further additives include water reducers and fluidifiers. Generally, though it is not intended to be limiting, the matrix may include 15 passages in the form of a cavity, fault, fissure, void or pore space through which fluid or gas may travel to cause leakage, flooding and / or contamination. The present method is particularly suitable to limiting or reducing water or gas inflow in geological formations surrounding mine shafts and other similar passages, although it is not intended to be limited to such applications. The present method 20 is equally applicable in any situation where it is desired to prevent or reduce liquid or gas inflow, such as building structures, underground excavations, waste disposal sites and foundations. The method may also be used to create barriers to liquid or gas inflow to or through a matrix. As noted above, such liquids may be other than water. 25 In particular, the present method includes measurement and analysis of parameters that are specific to the site that is to be treated and substantially at the time of site treatment. Preferably, the method includes measuring qualities of liquid, usually water, present within or flowing through the matrix to be sealed. Liquid present within the matrix is ideally collected and analysed to determine 30 properties such as pH, temperature, mineral content and salinity. Selection and concentration of components of the sealing composition, such as additives and inhibitors are then determined with reference to these site specific measurements in order to control the set time of the composition in the passage. CA 3005556 2018-05-22 7 In a particularly preferred embodiment of the invention, the method includes an additional step of measuring and / or analysing at least one component of the sealing composition and selecting further components with reference to said measurement or analysis of the at least one component. In particular, the 5 method includes analysis of a polymer or latex component of the sealing composition, whereupon one or more further additives are selected on the basis of variations in the latex, particularly variations that arise primarily due to the particular season that the latex has been harvested. Prior to, preferably immediately prior to, application of the sealing 10 composition or grout to the site to be treated, parameters of the site specific to the matrix are measured and analysed, particularly hydraulic and / or pneumatic parameters since the water or gas flow behaviour must be evaluated if effective sealing is to be achieved. Drilling and geological sampling techniques may be employed to do this. Said parameters may, and preferably do, include in situ 15 hydraulic conductivity testing to establish a series of baseline Lugeon values and to obtain an idea of the total aperture width of pervious features in the matrix; water take and dye testing to establish hydraulic conductivity of the passage or passages in the matrix; and presence or absence of flow conditions. These properties also provide an estimate of volume of sealing composition required for 20 sealing. This step also includes testing of properties of water present or flowing into the passage to be treated, particularly to test parameters such as pH, temperature, mineral content and salinity, which affect selection of the sealing composition to be used. Additional site conditions are also taken into consideration, such as temperature of the ground formation in and around the site 25 to be treated. Once hydraulic and / or pneumatic parameters are determined, the matrix is drilled to provide injection ports through which sealing composition is directed into the matrix. ln a particularly preferred embodiment of the invention, the method further 30 includes measuring and analysis of parameters following an initial application of the grout and optionally, following subsequent grouting application stages. One or more components of the sealing composition are modified, if necessary, in response to changes in said parameters. For example, the sealing composition for use in any second and subsequent applications to the site is modified in CA 3005556 2018-05-22 8 response to a) the formation of, or change in water or gas flow paths and water or gas flow through times within the matrix and / or b) to compensate for changes in the geology or other material properties of the matrix. In this regard, some sealing sites may have variable geology, variable permeability and variable requirements 5 for the formation of sealing barriers. Permeability measurements allow modification or adjustment of the set time of the grout introduced to the site in subsequent applications. In a preferred aspect, the method includes the step of introducing the sealing composition to the passage by injection. Preferably, components of the 1 o composition are introduced into the site independently such that the sealing composition is effectively composed in situ. That is, the sealing composition is a multi-component formulation wherein the various components are brought together and react therewith in situ in the passage. Desirably, components of the sealing composition are introduced into the 15 site by means of a suitable pump, preferably a multi-port pump, whereby the components are introduced via separate pump holes and associated injection points. Preferably, the pump is a displacement pump. Such pumping equipment and the ability to introduce components of the composition separately into the site advantageously enables a degree of control over introduction of the composition 20 to the passage to be sealed and hence control of setting time within the passage. In particular, it is advantageous that the pump be able to inject the composition into the passage at variable pressures, said pressure variation selected in response to changes in measured site specific hydraulic, pneumatic and chemical parameters. It is further preferred that the present method includes a primary 25 sealing composition injection phase and a secondary sealing composition injection phase. It is particularly preferred that the first injection phase introduce sealing composition into a passage with the flow of water or liquid or gas. The secondary injection phase preferably introduces sealing composition into the passage against water or gas flow, particularly once the water, liquid or gas inflow 30 has been arrested. The present invention therefore has, as an advantage, the ability to exercise control of set times of the sealing composition once introduced into the treatment site, allowing the composition to adequately permeate the encountered formations within the matrix a distance away from the injection point(s). Further, CA 3005556 2018-05-22 9 the desirably small particle size of particles within the polymer emulsion or colloid assist with permeation and desirable spread, both lateral and horizontal, of sealing composition within the matrix. An effective sealing barrier should result. In some sealing applications, it may be more convenient to have the ability 5 to introduce a single composition into a passage whilst still maintaining ability to vary or control the setting time of the composition in response to particular parameters or variables present at the site of application. In this respect, there is provided a further aspect of the present invention, which provides a method of limiting or reducing liquid or gas inflow through a matrix, such as, but not limited 10 to, a geological formation, with a sealing composition based on a polymer emulsion or colloid comprising a grout component; and a grout curing agent wherein a portion of grout component is mixed with a portion of grout curing agent, the ratio of grout component to curing agent being selected with reference to one or more parameters relating to said matrix, wherein the combined grout 15 component and curing agent are introduced into said passage where it is set or coagulated in a non-exothermic or low exothermic process to form a seal barrier, whereby rate of curing or setting of said grout component in said passage is controlled or varied by modifying the ratio of grout component to curing agent. This may also assist in temperature control during the non-exothermic or low 20 exothermic setting process. Particle density and size of particles within the emulsion or colloid may also be modified, while maintaining the desirably small particle size distribution, to vary curing rate or setting time. If particles have small size, a greater surface area is also generated, this positively affecting the flocculation / coagulation rate. 25 Desirably, coagulation or setting is initially delayed for a predetermined period of time. This is then followed by a relatively fast coagulation or setting of the sealing composition in situ in the matrix or passage being treated. That is, the time taken for the sealing composition to set or coagulate can be controllably delayed by modification of the ratio of grout component to curing agent to suit a 30 specific application. This can be achieved without uncontrollable temperature increase and disadvantages as described above. Preferably, the grout component is natural latex based such as a latex emulsion, colloid or aqueous dispersion. However, the grout component may also be a polymer based composition provided that such polymer composition CA 3005556 2018-05-22 10 can be cured in a non-exothermic or low exothermic curing process. Desirably, the grout component is aqueous to permit ready mixing with the curing agent The curing agent is comprised of one or more components, selected from agents capable of developing or reacting with the grout component to set or 5 coagulate the grout component in the matrix. To this effect, the curing agent desirably has a delayed setting or coagulation effect, so as to permit the combined mixture of grout component and curing agent to be pumped, injected or otherwise suitably introduced into the matrix and achieve sufficient penetration to form a sealing barrier to effect limitation of liquid or gas inflow. 10 In one embodiment of the invention, the curing agent is selected from agents that have the effect of lowering pH of the liquid. Preferably, lowering of pH occurs gradually over a period of time, the period of time being largely dependent on the ratio of grout component to curing agent. It is preferred that pH is lowered by generating acid via a reaction in-situ of the combined grout / curing agent 15 mixture. In the case of a latex based grout component being used, oxidation of an alcohol to a carboxylic acid within an aqueous latex dispersion is one such way to lower the pH as shown in the following equation: R OH + oxidising agent ➔ R-COOH 20 To this effect, the curing agent is in one preferred embodiment, an oxidising agent. The oxidising agent can be used to produce acids in the aqueous grout component upon addition thereto and mixing therewith. Nonlimiting examples of such an oxidising agent that can be used as the curing agent 25 are permanganate and chromium trioxide. According to a further preferred aspect of the present invention, the curing agent is selected from a class of alcohols referred to as polyols and may be a monomeric polyol, a diol, trial, tetrol or any other polymeric polyol. Non-limiting examples are monomeric polyols such as ethylene glycol or glycerine and 30 polymeric polyols such as polyethylene glycol. In a particularly preferred embodiment of the invention, the curing agent is a fatty acid ester of a polyol. Testing indicates that mixing a major portion of grout component with a minor portion of curing agent results in the initial formation of a small number of coagulates or solidified particles, whilst the majority proportion of the mixture CA 3005556 2018-05-22 1 1 remains in a liq u id form. The initially formed coagulates or particles act as an initiator or seed for formation of further coagulates or particles within the mixture which, over time, leads to coagulation or setting of substantially all of the mixture. Advantageously, modification of the ratio of grout component to curing 5 agent, for example by wt% has been found to enable control over the rate of setting. The grout component can therefore be combined with a predetermined quantity of curing agent, the quantity being determined largely with reference to parameters of the s ite or matrix to be treated, and introduced into the passage where it is set or coagulated in the passage at a rate that is optimal for that 1 o particular application. The present invention has particular utility in application to a matri x or ground formation, including soil, prior to excavation of a shaft or tunnel, such as excavated in mining operations. The method may also be applied to form perimeter sealing barriers and bunds whether to flow of water, other liquids (for 1 5 example oil or organic contaminants including solvents) and gases. The present invention advantageously is able to prevent or minimise water inflow i nto a shaft or tunnel being constructed in a ground formation in close proximity to a body of water, such as a river or aquifer. The present invention advantageously also enables minimisation or prevention of gas inflow into the s haft or tunnel or indeed 20 into any areas of the surrounding ground where it is not desired to permit gas to escape to. The method is conveniently controlled by a control unit which monitors site parameters such as those described above, and actuates equ ipment, such as pumps and valves to deliver the sealing composition to pre-determined locations. 25 D ETAILE D DESCRIPTION OF PREF ERRED EMBODIMENTS The present invention may be better understood from the following description of preferred embodiments and examples and with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a geological body , containing a shaft 30 having cracks or apertures in the matrix s urrounding the shaft that requires sealing to prevent or minimise water inflow into the shaft; Figure 2 is a front view of a section of a series of tubbing rings lining a shaft sunk into a matrix requiring treatment to limit water inflow into the shaft; CA 3005556 2018-05-22 12 Figure 3 is a cross-sectional view of a geological body with a mine shaft excavated therein and requiring treatment to limit water inflow, prior to any treatment; Figure 4 is a cross-sectional view of the geological body of Figure 3 being s treated to limit water inflow into the mine shaft in accordance with the present invention; Figure 5 is a cross-sectional view of the geological body of Figure 3, wherein a first further additive is introduced to the passage; and Figure 6 is a cross-sectional view of the geological body of Figure 3, 1 0 wherein a secondary injection phase of the sealing composition is undertaken The following description and examples are made primarily with reference to treatment of a geological body wherein a mineshaft is excavated, the mineshaft having cracks or apertures requiring sealing, primarily to prevent inflow of water. For example, water may be flowing or leaking into the m ineshaft through 1 5 passages in the form of cracks and fissures or through permeable unconsolidated matrix layers. However, the present invention is not limited to such applications and it should be understood that the present method may be successfully employed in a variety of situations where it is desired to stop or limit water inflow, such as, but not limited to, water inflows in deep and open cut mines, 20 underground dam sealing, underground silos and bunkers, basements, underground waste depository sites, salt mines and reservoirs and dams. The present method is equally applicable where it is desired to stop or limit gas flow such as, but not limited to gas leaking inappropriately from fractures in ground created as a result of a hydrofracturing operation. 2 5 Referring initially to Figures 1 and 2, there is shown a matrix 1 0, being a ground formation surrounding a mine shaft 1 4, where water penetrates through a fissure in surrounding rock and through pore spaces in an unconsolidated sand lens. Water is able to gain entry to the shaft 1 4 by passing through cracks in a wall of a tubbing segment 1 8, through fissures 1 6 between respective tubbing 30 segments 1 8 and through cold joints caused to form between the end of one concrete pour and the beginning of a new pour behind the tubbing segments 1 8, such as those depicted in Figure 2. In the construction of the shaft 1 4, the tubbings 1 8 act as a liner to the shaft 1 4 In known methods of shaft construction, it is typical to freeze the ground surrounding the shaft path in order to stabilise the CA 3005556 2018-05-22 13 ground formatio n . In this example, the present method is advantageously applied so that ground freezi ng becomes unnecessary a nd damage caused to the rock near the shaft 14 duri ng excavation activities can be repaired. I njection holes 20 are drilled i nto the matrix and through the tubbing 5 segments 1 8 at i ntervals around the face of the tubbing 1 8 i nside the shaft 14 The holes can be drilled either perpendicular to the face of the tubbing 1 8 or at an angle, such as 45°. To reduce cost, while allowi n g effective sealing, the layout of i njection holes 20 should min imise the number of i njection holes 20 required. To this end, i n jection holes 20 are i deally disposed at regular and substantially 10 equidistant intervals about the circumference of the tubbing 1 8. Injection ports 2 0 are drilled i n this manner about each tubbi n g segment 1 8 li n i ng the shaft 14. Any suitable drilli ng means can be used to create the i njection holes, such as by usi n g a percussive jackleg drill to drill t o the required depth. Percussive drilli ng may be necessary in hard rock formations. Rotary drilli ng is more suitable and i ncreases 15 the permeability of the formation. Samples of water present at the sealing site (site water) are collected from at least one area of leakage i n or aroun d the shaft 14. The water is tested to analyse chemi cal properties such as p H , temperature, mi neral content and sali n ity levels. Temperature of the ground formation at and around the site is also 20 measured. Hydraulic parameters of the matri x 1 0 must also be determi ned. The nature and extent of the hydraulic filed must be u nderstood if effective sealing i s to b e effected. In order to determi ne hydraulic parameters of con nectivity, penetration and spread of water i nflow, a suitable dye, such as a tracer dye, 25 hav i n g same flow characteristics as water but bei ng coloured so as to clearly contrast agai nst the shaft 14 and the site, i s i ntroduced i nto each of the i njection holes 20 . Seepage of the dye i nto the shaft 1 4 can be timed and visually assessed to determi ne permeation of water i nflow. Reporti ng of dye i ndicates where i nflow is occurri ng and where mai n water i n gress points are situated, for 30 example at the cold joi nts between concrete pours. Flow rate of the dye i s measured to determi ne flow properties of the dye within the matrix 1 0 when introduced at a particular rate and pressure. This g ives an i ndi cati on of the flow CA 3005556 2018-05-22 1 4 rates o f a solution o f the sealing composition, so that it can b e determi ned when to introduce suitable additives and at what concentrations. Having reference to para meters g round and water temperature, water p H , mineral content and salinity levels as well as flow properties o f water i n and s around the site and of temperature of the site , components and the respective concentrations of said components of the seal ing composition can be suitably selected. At sites where the temperature of the immediate and surrounding g round formation is less than about - 1 2°C, or over 1 00°c , the components of the seal ing 1 0 composition m ust b e selected accord ingly. For example, a cement based sealing composition can be selected preferentially over a latex-based sealing composition if the ground tem perature is too high. I t is also possible to use a combi nation of two d ifferent types of sealing composition. For example, a cement-based seal i ng composition can be used to bulk fi ll large voids and a latex-based sealing 1 5 composition can subsequently be used to fill smaller cracks and fissures. Steps can be taken to maintain a latex-based sealing composition above freezing temperature, for example by heating or add i ng freezing point depressants. Referring to the geotechnical assessment of the ground formation, particularly water permeability, standard cement o r m icrofine ( particles <30 20 m icron) is used. For exam p le, i f the size of the passage or apertures i n the formation is generally wider than 1 60 micron, the site can be treated with a standard cement composition. Apertures that are smal ler and which cause s low seepage, require a sealing composition having small particle distribution as described here. Additives and admixtures a re added to the cement based 2 5 composition to obtain desired rheology and set characteristics, having reference to the measured parameters of the site. Such additives may include latex. At a site where the temperature of the i m mediate and surrounding g round formation is - 1 2°C or greater, and water i nflow permeation testing indicates that there is presence of water flow conditions, it is desirable to use a m ulti- 30 component latex based c hemical composition, such as that described in Australian patent number 739427 . CA 3005556 2 0 1 8 -05-22 Date Rec;ue / Date Received 2024-02-12 1 5 Such a chemical composition ideally has a s a significant or bulk component, a latex emulsion or colloid, preferably at <30% of the total composition. Typically, the latex is provided in emulsion or colloidal suspension with water. It is preferred that the latex is a natural latex, as natural latex has 5 surprisingly been found to exhibit better sealing capabilities than synthetic variations and latex may also be cured in a non-exothermic or low exothermic setting process. Concentration of latex in water may be selected having reference to the chemical and hydraulic parameters determined in earlier steps of the method. The latex emulsion or colloidal suspension has a near uniform 1 0 dispersion of polymeric particles having a particle size distribution with 100% of polymer particles having size less than 2 microns, notably having average size about 1 micron. This particle size compares with a particle size range of 5 to 30 microns inorganic cement particles for Portland cement and a Tamcrete® product in which 58% of the inorganic particles have a particle size greater than 2 microns 15 and 100% of the inorganic particles have particle size less than 40 microns. The difference in particle sizing is beneficial for the selected latex emulsion based sealing composition since it can flow into and permeate fine cracks (i.e with dimension less, including significantly less, than 160 microns) at a lower pressure and without the risk of undesirable hydrofracturing that a cement based sealing 20 composition would indicate. Having reference to the aforementioned measured hydraulic parameters and chemical properties of the water and the site, one or more further additives are selected for combination with the latex emulsion for delivery to the passage to be treated. As the sealing composition is introduced into the water flowing 2 5 through the passage or passages requiring sealing and the sealing composition is carried throu gh the passage by the water, the water effectively becomes an ingredient in the sealing composition once it is introduced into the passage. The one or more further additives are therefore added to complement the chemistry of the water or to remedy chemical characteristics that can have an undesirable 30 effect on the sealing composition once introduced into the matrix. At sites having acidic water present within the matrix, setting or coagulation of the sealing composition may be prematurely induced upon introduction of the composition, whereupon the composition is unable to adequately permeate the matrix 10. If water analysis indicates a pH of value less CA 3005556 2018-05-22 1 6 than 7 , it is desirable to add an inhibitor component to alter the pH to an alkaline condition Such inhibitors are provided in alkaline solution generally above pH 10 or 1 1, so as to increase the pH of the water. These can include, for example, the kind found in detergents and soap like substances, non-limiting examples of 5 which are tripolyphosphate, the proprietary product KT (in powder or solubilised), which contains a mixture of sodium phosphates, or an alkaline potassium hydroxide ( KOH) . In treating a site that is acidic or slightly acidic, the inhibitor additive is injected or pumped into the passage and is combined with the latex component in situ within the passage. The degree of alkalinity of the inhibitor 1 0 additive is determined with reference to the p H measurement of the water. At sites where the water is particularly acidic, it is advantageous to first flush the passage with either a pH-neutral or alkaline solution, such as the proprietary product named C4 (product code XTMC4 1 36), which is a surfactant blend of surface acting agents, prior to introduction of any latex component so as 1 5 to increase t he pH of the water and thereby avoid premature setting within the passage. The introduction of such a component into the passage also permits the sealing composition to be pumped into the passage at a reduced pressure, since the introduction of this solution enhances the penetrability of the sealing composition in the passage irrespective of whether the matrix 1 0 is predominantly 20 a rock or soil formation. Conversely, it can be useful to acid flush the permeable features intersected by the injection holes 20 to displace the ground water therein. The flushing action assists to enhance the permeability of the ground formation and permits better penetration of the sealing composition once introduced. It is 25 typical to use a weak acid based stabiliser solution for this flushing purpose. However, other types of dilute acids can also be used, a non-limiting example of which is hydrochloric acid (HCI) . Introduction of an acid solution can advantageously open or re-open permeability of the formation of the matrix 1 0, effectively dissolving deposits of material that can otherwise impede travel of the 30 sealing composition within the permeable features of the matrix 10. At sites having water containing high salt content, such as may be experienced when sinking a shaft in a body of salt, premature setting or coagulation of the composition within the passages can also be experienced. Where water conductivity measurements indicate high salinity, it is desirable to CA 3005556 2018-05-22 17 introduce one or more inhibitor additives, such as those described above , that act to i nhibit setting or coagulation of the sealing composition within the passage. Alternatively or in addition , it can be advantageous to first treat the water within the passage to reduce salinity prior to introduction of the latex component. That 5 is, the passage is flushed so as to displace the grou nd water immediately prior to introduction of the compositio n . Prior t o introduction o f the customised sealing composition, co ntai ning compon e nts se lected with reference to the properties of the matrix 1 0, each injection hole 20 is water tested to establish a series of base line Lugeon values 1 o and obtain an idea of the total aperture width of the permeable features in the treatment site. This testing also provides an indication of the volumes of sealing composition likely to be req uired to seal these features so as to effectively seal them and prevent fl uid ingress and l eakage into the shaft 1 4. During initial phases of introduction of the multi-component composition 15 into the passage , the composition is form ulated to provide an extended set time so as to a l l ow for optimum spread and penetration of sealing compositio n into the formation. It is u ndesirable for the sealing composition to set too close to the injection port 20 as this then req u ires drillin g of further injection holes 20 in order to e nable introduction of additio nal composition . Ideal ly, introduction of the 20 sealing composition creates a l ateral grout spread over a distance which is more or l ess equal to the distance between the i njection hole 20 and the liner of the shaft 1 4, in this case the tubbing 1 6. At the very l east, grout spread should be sufficient to form overlapping grout cylinde rs around the shaft 1 4 . As introduction of the sealing composition into the passage, or n etwork of 25 passages within matrix 1 0 progresses, the set time is gradual ly reduced by addition of more activator additive. This e nables grout spread to be limited to within the target area, being the mini m u m area of the matrix 1 0 that req uires application of the sealing composition to minimise or limit water or other liq uid inflow, thereby minimising waste of sealing composition and u n n ecessary 30 distribution within the matrix of the gro u nd fo rmatio n. As the gro uting operation proceeds, the set sealing compositio n will block and fill ope n parts of the matrix, leading to a change in water flow paths and flowthrough times. It is therefore required that adjustments to the sealing composition set time be made in response to these changes . It is desirable then, that further CA 3005556 2018-05-22 1 8 measurements of hydraulic parameters of the matrix 1 0 and chemical properties of the water be made as the sealing composition is applied to the passage and modifications to the overall composition be made with reference to these measurements . If the apparent Lugeon value is not shown to decrease over time, 5 it means that the sealing composition is continuing to fill voids in the matrix. Based on volume of sealing composition already injected, set times of the sealing composition can be gradually reduced by, for example, adding greater quantities of activator additive or the same volume at a greater concentration. If the apparent Lugeon value shows decrease over time, it is indicative that the sealing 1 0 composition is in a permeation mode. The sealing composition can therefore continue to be introduced into the passage with no changes being made to set time. However, if measurements indicate that the apparent Lugeon value is decreasing at a rapid rate, adjustments are made to the individual components of the sealing composition to extend the setting time within the passage. 15 Injection of the sealing composition commences at the lowermost tubbing segment 1 8 within the shaft 1 4 and progressively moves upwards. Sealing composition is injected into a first injection hole 20 until such time as the sealing composition is observed in next injection hole 20 in that tubbing segment 1 8. Sealing composition is introduced into the second injection hole 20 and each 20 subsequent injection hole 20 until the entire circumference is treated. Injection of the sealing composition then moves upwardly to the next tubbing ring 1 8. However, the sealing composition can be injected into injection holes 20 in any particular order, so long as the sealing composition is able to fill the void between the outer circumference of the tubbing rings 1 8 and the surrounding ground. 25 With reference to the measured site hydraulic parameters and chemical properties of the water, sealing composition in the present example is injected into the passage with minimal pressure. It is desirable to maintain a low injection pressure so as to avoid any issue of hydro-fracturing of the surrounding matrix. In this application, the injection pressure desirably should not exceed 1 . 25 to 2. 5 30 times the hydrostatic head. Ideally the injection pressure is determined based on rock mechanics of the matrix at the site and with reference to the depth of the injection holes 20. Advantageously, inhibitor additive is introduced into the passage by means of a multi-port displacement pump. The multiport nature of the pump enables CA 3005556 2018-05-22 19 introdu ction of the individual components of the sealing composition so that they effectively only react with each other in situ within the passage. Injection of the components of the sealing composition is desirably increased from hydrostatic head to maximum pressure slowly and gradually. Typically , as water within the 5 passage is sealed off, the pressure will increase automatically . If necessary and particularly in order to avoid hydro-fracture of the surrounding ground formation, injection pressures, and if necessary sealing composition properties, are adj usted to suit the requirements of the specific site and with reference to measured parameters specific to the site, including the distance from the injection hole 20 it 10 is desired to distribute the sealing composition and form sealing barrier(s). Where the latex emulsion component is used, the sealing composition is injected into the water flowing or present in the passage via the various injection holes 20. As the latex component flows within the passage, it is activated at least partially by agitation, causing the sealing composition to coagulate to form a seal 1 5 within the passage o r network of passages within matrix 1 0. If measured flow conditions dictate, for example flow velocity is high, say 200L per second, a chemical activator component is added to increase the rate of coagulation and setting within the passage. Following an initial treatment phase where sealing composition is 20 introduced into the site and setting initiated and completed, it is highly desirable that at least a second treatment phase be conducted . It has been found that following treatment of a site with sealing composition, water often recharges from local aquifers and finds a new route, being a path of least resistance, into the shaft 14. Due to the disturbed flow path of the water, new leaks into the shaft 14 25 can occur and these must be dealt with accordingly . Steps as described above, being drilling of injection holes, analysis of site matrix with a suitable dye to assess permeation of water inflow and chemical analysis of site water are carried out. Having reference to these measured parameters, species of components and their concentrations are selected and introduced into the passage 30 substantially as described above. Referring now to Figure 3, there is shown a ground formation 100 wherein a t unnel 14 1 , such as a mine shaft, has been excavated underneath a body of water, such as an aquifer, flowing through the matrix 1 0 of the ground formation 100. Water inflow into the tunnel 1 4 1 must be stopped or limited so that the CA 3005556 2018-05-22 20 tunnel 1 4 1 does not flood. In this example, the tunnel 1 4 1 is an open formation, having no lining between the tunnel interior and the surrounding matrix 10, composed predominantly of rocks and unconsol idated formations including loose rocks. Thi s type of formation is susceptible to threat of hydro-fracturing and 5 potentially dangerous rockfalls or mudslides . As with the previous example, water take and dye tests are conducted to establish hydraulic conductivity of fissures within the matrix and contributing to water i nflow into the shaft. It has been found , in unconsolidated geological formations, that hydraulic fracturing can be a significant problem. Once open 1 o parts of water inflow fissures become plugged with set or coagulated sealing composi tion, the inflow will eventually become aperture limited, whereupon water velocity will increase and result in additional scouring within the matrix. This can also occur after a site has been successfully treated with the sealing compos ition. For this reason, it is desirable for the method to include a primary injection phase 15 (see Figures 4 and 5), where the sealing composition is introduced into the passage with the flow of water or gas via injection hole 20 1 ; and a secondary phase, where the sealing composition is introduced against the water flow once the i nflow into the tunnel 14 1 has seized (see Figure 6 ) . The two-phase application advantageously serves to create an impermeable curtain of sealing 20 composi tion as above described. As with the previous example, an in situ hydraulic conductivity test is conducted prior to introduction of any sealing composition into the passage. This establishes a series of baseline Lugeon values and provides an indication of total aperture width of pervious features within the matrix. Similarly, water in the site i s 25 tested for pH, temperature, mineral content and salinity levels . During injection of the sealing composition, it i s advantageous to reduce set times of the sealing composition in the passage as injection continues so as to prevent setting or coagulation of the sealing composition too close to the injection holes 20 1 and to achieve a lateral spread of sealing composition that is 30 sufficient to create an effective barrier to prevent water inflow into an excavation. At the commencement of i njection, the multiple components of the composition are i ntroduced and initially permitted to flow through and leak into the tunnel 14 1 ( Figure 4 ) . This permits measurement of an initial flow through time or resident time. CA 3005556 2018-05-22 2 1 I t i s the aim of the present method to attain a lateral spread of the sealing composition which is substantially the distance between the i njection hole 201 and the perimeter of the pervious featu re. l t i s also important to ensu re that the sealing composition does not set too close to the injection hole 20 1 as this will 5 then require drilling of additional holes and hence undesirable additional cost Setting time of the sealing composition is gradually reduced by introduction of greater quantities or greater strength of a suitable activator additive ( Figure 5), the type and composition of which is selected, as above described, with reference to the measured parameters specific to the site. Set time is reduced to the point 1 0 where the sealing composition no longer washes out of the pervious features of the matrix 100, but is rather bound within the matrix 100 to form a seal. Setting is non-exothermic avoiding issues such as premature setting, shrinkage and poor mechanical properties encountered with non-natural latex systems. Optionally, activator component can be introduced into the water flow via a 1 5 separate injection hole 20 1 to one or more other components of the sealing composition. For example, referring to Figure 5, in the instance where a latexbased sealing composition is employed, the latex component is introduced to the water flow via first i njection hole 20 1 a and activator component is introduced via second i nj ection hole 20 1 b. Injection hole 20 1 b intersects the passage 20 downstream from injection hole 20 1 a. In such a case, latex component is pumped into the water flow within the void or passage via injection hole 20 1 a, where it is carried towards the tunnel 14 1 by the water flow within the passage. Activator component is introduced into the passage via injection hole 20 1 b where it is mixed with latex component flowing downstream. The mixed sealing 2 5 composition is then set or coagu lated so as to form a seal barrier, preventing fu rther water inflow into tun nel 14 1 . A s indicated, it is desirable that a secondary injection o r sealing phase be undertaken, this phase being introduced against the water flow, as shown in Figure 6. If it is observed that d u ring the secondary injection phase, there is no 30 fu rther pressure build up at a given flow rate, it is indicative that the set composition is being pushed back too far into the matrix and the sealing composition is penetrating too far away from the target site, leading only to wastage of material. If this is the case, set time of the sealing composition should be gradually reduced by reduction in activator additive and / or increase in CA 3005556 2018-05-22 22 inhibitor additive into the matrix. For example, the pH of the composition in the matrix is transitioned from an acidic pH to a more alkaline pH . Referring to Figure 6, the secondary injection phase can be undertaken by opti onally drilling a further injection hole 2 0 1 c, which intersects the passage s upstream of the passage (now sealed with sealing composition). The latex component of the sealing composition is pumped via injection hole 2 0 1 a and is forced upstream within the passage since the downstream part has been sealed with sealing composition. Activator component is pumped into the passage via injection hole 2 0 1c where it is mixed with the latex component and the sealing 10 composition is caused to set. The primary injection phase, introducing and setting sealing composition downstream within the passage is therefore a reactive application of the sealing composition, to remedy water inflow into the tunnel 1 4 1 . Application of the sealing composition via the secondary phase, where it i s introdu ced upstream and against water flow, i s proactive treatment, where water 1 s scouring and hydrofracturing of the matrix 100 is prevented. The present invention is also particularly useful in proactive treatment of a formation prior to excavation, having the benefit that it is not necessary to have to deal with water inflows into the excavated mine shaft or other structures for that matter during mining. It will be understood that use of the method is not confined 20 to mining applications and it may for example be applied to civil engineering applications as well. The following example of application of the present method relates to a pre-excavation application to prevent water inflow into a shaft being constructed in a ground formation in close proximity to a large body of water, such as a river. In this example, the ground formation can often contain 25 significant quantities of fractured sandstone and unconsolidated sand layers. To obtain relevant geotechnical information regarding the site, a pilot hole is drilled within proximity of the planned shaft. Obtaining samples in this manner permits at least identification of the geological properties of the ground formation. In the event that the ground formation is found to consist mainly of sandstone and 30 unconsolidated sandstone, the properties of both types of matrix need to be accounted for when selecting the components of the sealing composition . To accommodate the possibility of vertical or sub-vertical fissures and / or saturated sand lenses being encountered during the mine shaft excavation, the sealing composition, once applied, should construct a curtain around the CA 3005556 2018-05-22 23 proposed path of the shaft in order to reduce permeability of the surrounding formation and minimise water inflow into the future shaft. A series of primary injection holes, preferably spaced equidistant around the proposed shaft perimeter, are drilled. Desirably, the primary injection holes are drilled offset from 5 the outside edge of the proposed shaft. Typically, about eight of these primary injection holes are drilled about the perimeter. It is desirable for a further number of secondary injection holes to be drilled to measure effectiveness of the application of the sealing composition during and after first application. The secondary injection holes are located substantially at a mid-point between the 10 primary injection holes. Each injection hole is drilled to a required depth, dictated by the proposed depth of the shaft. Each injection hole is also dri lled so as to be able to accommodate the insertion of a packer to enable pressure grouting at various stages of the application. Any suitable packer can be employed for this purpose. For example, a single, open ended inflatable packer can be suitable or 15 a double filament packer. Prior to selection of components and introduction of the sealing composition into the passage, each injection hole is water tested to establish a series of base line Lugeon permeability values and to obtain an idea of the total aperture width of the pervious features in the ground formation. Similarly, water 20 within injection holes is sampled and analysed to test parameters such as pH, salinity, mineral content and temperature. Following water testing activities, the injection holes and the pervious features intersected thereby can be flushed with a fluid, selected with reference to measured chemical properties of the ground water as described above, so as to 25 displace the ground water. Depending on conditions of the site, particularly pH of the water, it may be desirable to flush with a slightly acidic solution. The flushing action advantageously acts to enhance the permeability of the ground formation by altering the chemical conditions therein to suit the sealing composition, which assists in the formation of an appropriate curtain of set sealing composition. 30 Optionally, and with reference to the measured parameters of the site, a stabilising additive, being a surfactant blend of surface acting agents, such as detergent, is introduced into the matrix via the injection holes so as to enhance penetrability of the sealing composition by essentially acting as a lubricant within the passage. CA 3005556 2018-05-22 24 Selection of types and concentrations of the seal ing composition is made with reference to measured parameters of the site and the water flowing therein, substanti ally as described above in relation to earlier examples. As described above, once injection of the sealing composition into the passage is com menced, 5 careful and continuous assessment is requi red, to monitor, for example, changes in Lugeon permeability values and then to modify composition set time by modification of additives, substantially as described above. R esponse ti mes to adjustments in the make-up of the sealing composition are likely to be considerable in an application such as this, as the depth of the injection holes and 1 o of the passages being sealed i s li kely to be very deep. It is i mportant then, for changes to the composition to be gradual so as to avoid shot-gun refusals (premature setting of the sealing composition before it has been permitted to spread sufficiently) and loss of access to the pervious target zone. It is also desirable to modify the pressure at which components of the 15 composition are introduced into the passage with reference to the measured parameters relating to the site. I n the present instance, the mechanics, e.g. rock mechanics of the matrix will largely determine the suitable pressure to enable adequate penetration of the sealing composition in the matrix without causing damage such as hydrofracturing. 20 Having regard to measured parameters of the site and the water flowing therein, measured before, during and / or after any treatment of the site to prevent or minimise water inflow substant ially as described above, i t may be desirable or more convenient to treat the site by introduction of a single composition into the passage to be treated. In such an i nstance, it is still required to have the ability to 25 vary or control setting time of the composition, particularly in response to measured parameters or variables of or at the site. In such c ircumstances, an alternative embodiment of the present i nvention may be more suitable or convenient. In this embodi ment, the sealing composition is comprised of at least a 30 g rout component and a curing agent A major portion of grout component i s m ixed with a m inor portion o f curing agent prior to introduci ng the combination to the passage requiring sealing. That is, the combined g rout component and curing agent are i ntroduced into the passage where it is set or coagulated to form a seal. Advantageously and conveniently, the rate of or overall time taken for setting or CA 3005556 2018-05-22 25 coagulation of the combination i n the passage can be controlled or varied by modifying the ratio of grout component mixed with curing agent The grout component can be either latex based, such as a latex emulsion, colloid or aqueous dispersion; or can be a polymer based grout composition 5 having the same or similar particle size d istribution to that described above provided that setting is a non-exothermic or low exothermic process. In either case, the grout component is substantially aqueous, firstly to enable ready mixing with the curing agent and also to facilitate fluid movement of the combined grouUcuri ng agent i nto and through the passage to be treated. 1 0 The curing agent is selectable with reference to parameters of the site and to the specific constitution of the grout component, noting once again that the curing or setting process should be non-exothermic or low-exothermic. The curing agent is a composition or chemical that is capable of d eveloping or reacting with the grout to set or coagulate the grout component in the passage i n 1 5 a manner whereby setting or coagulation i s initially delayed. This permits the combined liquid mixture of grout and curing agent to be pumped, injected or otherwise introduced into the passage (such as has already been described above) whilst achievi ng sufficient penetration within the matrix or passage to effect limitation of liquid inflow. That is, the mixed grouUcuring agent must remain 2 0 i n a liquid form sufficiently long enough t o reach those regions o f the matrix or passage. The exact period of time required for the m ixture to remain liquid is dependent on measured site parameters, such as has been d iscussed above. The degree of penetration of the sealing composition in the matrix or passage i s also a determining factor i n deciding how long the mixture i s t o remain i n a liquid 2 5 state and this in turn can be deciding factor in selection of the curing agent for any particular application. I deally, curing or setting is initially delayed and is then followed, after a predetermi ned period of time, with a relatively fast setting of the sealing composition within the passage. Particularly if the grout component is a latex based composition which 30 cures in a non-exothermic process, the curing agent is desirably selected from agents that have the effect of lowering the pH of the liquid gradually over a period of time to a pH that effects complete setting or coagulation of the grout component. In the case of a latex based composition, this is typically a pH of CA 3005556 2018-05-22 26 about 3. The pH is lowered g radually by virtue of generation of acid i n-situ of the combined g rout / curing agent mixture. One such way of lowering the pH over time is by use of oxidising agent as the curing agent The oxidising agent can be used to produce acids in situ in the 5 aqueous g rout component. Non-li miting examples of suitable oxid ising agent for use as the curing agent are perm anganate and chro m i um trioxide. Polyols may also be used. Further description of curing agents and coagulation behaviour is provided in the Applicant's Australian Patent Application No. 201 32660 1 8 . 1 0 Modifications a n d variations a s would b e apparent to the skil led addressee are deemed to be within the scope of this invention. 15 CA 3005556 2 0 1 8 -05-22 Date Rec;ue / Date Received 2024-02-12

Claims

27 Claims 1. A method of limiting or reducing permeability of a permeable matrix to limit or reduce liquid or gas inflow within said permeable matrix, the method comprising measuring one or more parameters relating to said permeable matrix and selecting one or more components of a multi-component sealing composition based on a polymer emulsion or colloid with reference to said measured parameters and introducing said components of said sealing composition by pumping into said permeable matrix at a pressure varied in response to changes in the measured parameters relating to said permeable matrix; wherein measuring said parameters includes measurement of hydraulic parameters and measurement of at least one quality of liquid present within said permeable matrix; wherein said sealing composition is set or coagulated in a non-exothermic process to form a seal barrier by shear or by contacting said polymer emulsion or colloid with at least one selected additive; and wherein said polymer emulsion or colloid contains, prior to purposeful setting or coagulation whether due to shear or interaction with said at least one selected additive, particles of said polymer emulsion or colloid and particles of said at least one selected additive having a size distribution smaller than for Portland cement.

2. The method as claimed in claim 1 wherein said particles of said polymer emulsion or colloid and particles of said at least one selected additive, have a particle size distribution with average particle size being less than 5 microns.

3. The method as claimed in claim 2 wherein said polymer emulsion or colloid comprises a substantial proportion of particles with uniform particle size.

4. The method according to any one of claims 1 to 3, wherein said at least one quality of liquid is selected from the group consisting of pH, temperature, mineral content and salt content. CA 3005556 Date reçue / Received date 2024-12-09 28 5. The method according to any one of claims 1 to 4, wherein the hydraulic parameter includes at least one parameter selected from the group consisting of flow rate, matrix permeability, Lugeon values and hydraulic conductivity.

6. The method according to any one of claims 1 to 5, wherein the measured parameters include pneumatic parameters of said permeable matrix.

7. The method according to any one of claims 1 to 6, wherein the sealing composition is introduced into passages of said permeable matrix by a primary injection phase and a subsequent secondary injection phase.

8. The method according to claim 7, wherein the primary injection phase introduces sealing composition into the passage with the flow of liquid or gas in the passage.

9. The method according to claim 7 or 8, wherein the secondary injection phase introduces sealing composition into the passage against the flow of liquid or gas.

10. The method according to any one of claims 1 to 9, wherein components of the sealing composition are introduced into passages of said permeable matrix and react together in situ in the passage.

11. The method according to claim 10, wherein said passages have a dimension substantially narrower than 160 microns.

12. The method according to any one of claims 1 to 11, wherein the sealing composition is introduced into a ground formation prior to excavation of the ground formation.

13. The method according to any one of claims 1 to 12, wherein particle density and size of particles within the emulsion or colloid are modified, while maintaining said particle size distribution smaller than for Portland cement, to vary at least one of curing rate and setting time.

14. The method according to any one of claims 1 to 13, wherein coagulation or setting is initially delayed for a predetermined period of time. CA 3005556 Date reçue / Received date 2024-12-09 29 15. The method according to claim 14, wherein the initial delay of coagulation or setting is followed by a relatively fast coagulation or setting of the sealing composition in situ in the matrix or passage being treated.

16. The method according to any one of claims 1 to 15, wherein the polymer emulsion or colloid is latex based.

17. The method according to any one of claims 1 to 16, wherein said selected additive is selected from agents capable of developing or reacting with the polymer emulsion or colloid to set or coagulate the polymer emulsion or colloid in passages of said permeable matrix.

18. The method according to claim 17, wherein said selected additive is selected from agents that are able to lower pH.

19. The method according to claim 2, wherein said particles of said polymer emulsion or colloid, and said additive particles, have an average particle size less than 1 micron.

20. A sealing composition when used in a method according to any one of claims 1 to 19 comprising a pumpable coagulable polymer emulsion or colloid contactable with at least one selected additive which interacts with said polymer emulsion or colloid to form a coagulated mass for forming a sealing barrier in a non-exothermic setting process, wherein said polymer emulsion or colloid contains, prior to purposeful coagulation due to interaction with said at least one selected additive, particles of said polymer emulsion or colloid and selected additive particles, said particles having a size distribution smaller than for Portland cement. CA 3005556 Date reçue / Received date 2024-12-09