AU2017100604A4 - Method of limiting or reducing permeability of a matrix to liquid or gas flow - Google Patents

Abstract

The present invention is directed to a method of limiting or reducing permeability of a matrix to limit or reduce liquid or gas inflow within a passage in the matrix, the method comprising delivering to said passage a coagulable polymer emulsion or colloid, preferably a latex emulsion or colloid, for contacting with at least one selected additive which interacts with said polymer emulsion or colloid to form a sealing composition barrier to reduce liquid or gas inflow within said passage, wherein said polymer 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. Fig 1. 38 ----... 42 32a

Description

1 2017100604 24 May 2017

METHOD OF LIMITING OR REDUCING PERMEABILITY OF A MATRIX TO

LIQUID OR GAS FLOW

Field of the Invention [0001] The present invention relates to a method of limiting or reducing permeability of a matrix to liquid or gas flow. The method may be used for sealing passages such as cavities, fissures and like formations as encountered, for example in geological bodies, for example in rocks surrounding mineshafts to prevent flow of water, other liquids or gases through the passages. 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 situations.

Background to the Invention [0002] From US Patent No. 4296932 is known a method of sealing faults or like passages in geological bodies situated close to mineshafts and like structures, wherein a sealing composition comprising a rubber latex and a bituminous material is used to seal the passages. Bituminous material is included in emulsion with the latex to prevent formation of a film in the latex when being injected. Such a film can form under even low pressure, limiting the depth of penetration into the fault. Such a film can also be easily broken due to the limited depth thereof.

[0003] However, it has been found that appropriate sealing of faults, cracks or like passages may require injection of sealing composition at very high pressures, such as in excess of 10 MPa and perhaps as high as 20 MPa. At these pressures, pure natural latex, being incapable of resisting hydrostatic pressure without setting is unsuitable as it cannot be handled in the pumping equipment capable of achieving the required order of pressure.

[0004] Thus, in these situations latex cannot be used and the cost and sealing advantages that latex might enjoy in other situations is lost. Further, it is not desirable to use bitumen in such high pressure applications as it is a difficult material to pump and is not of itself suitable as a sealing agent even though it may promote coagulation of latex. 2 2017100604 24 May 2017 [0005] The Applicant has developed latex based sealing compositions successfully used in a range of sealing applications, from mining applications through to civil engineering applications such as the repair of tunnels.

[0006] The Applicant’s Australian Patent No. 739427 discloses a method of sealing a passage in a body such as a geological formation with a seal composition comprising delivering under pressure into the passage an admixture of latex and one or more of the following components: a friction resistant material, an extreme pressure additive; and a plasticiser, these components in total being present in quantities not greater than about 1% by weight of the mixture. The components may typically include organic and/or inorganic origin viscosity enhancing materials, detergents and/or soap.

[0007] The Applicant’s Australian Patent No. 2009253842 discloses a method of sealing a passage in a body with a sealing composition comprising (a) a major proportion of a latex emulsion or colloid; and (b) a minor proportion of lauric acid or laurate compound; and (c) at least one further selected additive, ideally a latex coagulation inhibitor, wherein the sealing composition is pumped into the passage where it is set or coagulated to form a seal.

[0008] The Applicant’s Australian Patent No. 2013266018 discloses a method of limiting or reducing permeability of a matrix to liquid or gas flow including the 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.

[0009] The latex based sealing compositions described in these applications enable efficient sealing. However, permeation of sealing composition into a matrix including passages, fissures, faults, cavities or other voids is important to ensure sealing of voids possibly with small dimension. In this regard, and has been alluded to above, cements and bitumen have disadvantages for such application even though they are readily available and generally inexpensive sealing compositions. 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. 3 2017100604 24 May 2017 [0010] It is the 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 flow which addresses the above problems or provides a useful alternative.

Summary of the Invention [0011] With such an object in view, the present invention provides in one embodiment a method of limiting or reducing permeability of a matrix to limit or reduce liquid or gas inflow within a passage in the matrix, the method comprising delivering to said passage a coagulable polymer emulsion or colloid for contacting with at least one selected additive which interacts with said polymer emulsion or colloid to form a sealing composition barrier to reduce liquid or gas inflow within said passage, wherein said polymer 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.

[0012] 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, wherein said polymer 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.

[0013] The particles include polymer particles and any additive particles present.

[0014] Portland cement has a typical particle size distribution lying between 5 and 30 microns. The desired polymer emulsion or colloid has a particle size distribution substantially smaller with average particle size in one embodiment being less than 5 microns, preferably less than about 2 micron, 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. This particle size eases pumpability of the polymer or emulsion or colloid, which can be described as a grout component, even into voids of narrow dimension allowing pumping equipment costs to be optimised for the sealing application. 4 2017100604 24 May 2017 [0015] Advantageously, the sealing composition or grout comprises at least one latex-based component (i.e the grout component) and one or more selected additives. It is preferred that such 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 latex emulsion or colloid and lauric acid or laurate compound; and at least one further component which may include the selected additive. The at least one further component is advantageously selected at least partially by reference of measured parameters of the site to be treated, for example chemical, hydraulic and/or pneumatic parameters as discussed in more detail in the Applicant’s Australian Patent No. 2013266018, the contents of which are hereby incorporated herein by reference.

[0016] The polymer emulsion or colloid desirably includes coagulation or setting 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 within the passage. The 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 cracks that might not even be subject to water leakage prior to sealing of larger cracks or voids, 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 passage has high salt concentrations, that is, the water may be substantially brine, the water in the passage can be treated with an inhibitor additive to prevent early coagulation or setting of the sealing composition in the passage. A non-limiting example of such an additive is the proprietary product KT which contains 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.

[0017] The selected additive conveniently includes a coagulation activator or curing agent to initiate or promote setting. Non-limiting examples of these additives are alkaline compounds; plasticisers, carboxylic acids, borates, silicates and hydroxides as well as metal salts thereof. Further additives include water reducers and 5 2017100604 24 May 2017 fluidifiers. Such activators desirably initiate a non-exothermic setting process. It may be more convenient to have the ability to introduce a single composition into the passage whilst still desirably 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 case, the further selected additive conveniently includes a curing agent and the combined polymer emulsion or colloid and curing agent are introduced into the passage where it is set or coagulated to form a seal. Rate of curing or setting of polymer emulsion or colloid, i.e the grout component, may then be controlled or varied by modifying the ratio of grout component to curing agent. Particle density and size of particles within the emulsion or colloid may also be modified 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. The curing agent may be selected from the group consisting of agents that have the effect of lowering of the pH of the liquid; and oxidising agents such as permanganate and chromium trioxide. Other potential curing agents, including alcohols and polyols (such as monomeric polyols, diols, triols, tetrols and other polymeric polyols which may be used as curing agents in admixture with oxidising agents) are described in the Applicant’s Australian Patent No. 2013266018, incorporated herein by reference. Curing may be induced, in some instances, by selected equipment, for example being capable of irradiating and cross-linking the grout component.

[0018] Still further additives that may be included within the polymer emulsion or colloid improve flow properties, such as by viscosity enhancement. Such additives may be inorganic or organic in nature. Inorganic compounds have been mentioned above. Suitable organic compound additives are desirably hydrophilic and may include carboxylic acids, gums, polymers (in particular acrylates), carbohydrates (including for example proteins such as gelatin, polysaccharides or polysaccharide derivatives (particularly the alkyl cellulose family of polysaccharides). Low molecular weight, especially C1 to C3 alkyl, preferably saturated but alternatively unsaturated, and methyl and ethyl cellulose - hydroxylated or carboxyated if desired are suitable additives. Hydroxymethyl and hydroxyethyl cellulose (Walocel) is particularly preferred. Other polysaccharides and polysaccharide salts that may be used include 6 2017100604 24 May 2017 algins and pectins and alginates. Metal salts of polysaccharide derivatives, such as alginic acid, may be employed.

[0019] In a preferred aspect, the method includes the step of introducing the polymer emulsion and additive mixture to the passage by injection at high pressure. Desirably, components are introduced to the matrix by means of a suitable pump, preferably a multi-port pump, whereby separate components for the sealing composition are introduced via separate pump holes. Preferably the pump is a positive displacement pump. Further description of options for delivering the components of sealing compositions into the matrix is provided in the Applicant’s Australian Patent No. 2013266018, incorporated herein by reference. In summary, the present method has, as an advantage, the ability to exercise control of set times of the sealing composition once introduced to the treatment site, allowing the composition to adequately permeate the encountered formations within the matrix a distance away from the injection point(s). Again, the small particle size of particles within the polymer emulsion or colloid assist with permeation and desirable spread, both lateral and horizontal within the matrix.

[0020] The method is conveniently controlled by a control unit which monitors site parameters, such as those described above, and actuates equipment, such as pumps and valves, to deliver the sealing compositions to pre-determined locations.

Detailed Description of Preferred Embodiments [0021] The method and composition of the invention will be more fully understood from the following description of a preferred embodiment made with reference to the accompanying Figure 1 which is a schematic cross-sectional view of a matrix 10 in the form of a body, such as a geological formation, containing a mineshaft having cracks requiring sealing. For example, there may be a problem with water leakage through cracks and fissures into the mineshaft. If allowed to proceed unchecked, the mineshaft could be flooded with serious consequences.

[0022] As schematically shown in the Figure, water penetrates through a fissure in surrounding rock matrix 32 at a level 32a below the area in which water leakage occurs and passes through face 34 and cracks 30 and joints 30a in lining 31 to enter into the mineshaft 14. Analysis of the fault precedes any further steps in sealing to 2017100604 24 May 2017 7 prevent water leakage. Samples of water at the site are collected for analysis of chemical properties such as pH, temperature, mineral content and salinity levels. The water analysed as acidic.

[0023] Hydraulic parameters of the matrix 32 must also be determined. The nature and extent of the hydraulic field must be understood if effective sealing is to be effected. In order to determine hydraulic parameters of connectivity, penetration and spread of water inflow, a suitable tracer dye - having the same flow characteristics as water but being coloured so as to clearly contrast against the mineshaft 14 and the matrix 32 is introduced through suitable injection holes (not shown). Seepage of the dye into the mineshaft 14 can be timed and visually assessed to determine permeation of water inflow. Reporting of dye indicates where inflow is occurring and where main water ingress points are situated, for example at crack 30 and the joints 30a. Flow rate of the dye is measured to determine flow properties of the dye within matrix 32 when introduced at a particular rate and pressure. This gives an indication of the flow rates of a solution of the sealing composition, so that it can be determined when to introduce suitable additives and at what concentrations.

[0024] Having reference to parameters ground and water temperature, water pH, mineral content and salinity levels as well as flow properties of water in and through matrix 32 and crack 30, the sealing composition can be suitably selected. More description of a selection process for various matrix characteristics is provided in the Applicant’s Australian Patent No. 2013266018, incorporated by reference.

[0025] As most flows of water are likely to occur through fissures of larger dimension, it is desirable to seal cracks of large diameter prior to addressing water flows through smaller fissures or faults. An alternative, more preferable, approach is to address associated fissures or faults, especially where micro or small cracks are present, simultaneously through a curtain approach in which sealing composition is applied, in manner analogous to a curtain to seal the associated fissures and faults.

[0026] In a preferred method, a number of passages - in the example shown two passages 38 and 40 are drilled, by percussive or more preferably rotary drilling (to minimize prospects for hydrofracturing) through the lining 31 of the mineshaft 14 to 8 2017100604 24 May 2017 the fault below large fissures and cracks, for example crack 30. In this region, there also exist cracks of very narrow dimension, less than 160 microns and even smaller.

[0027] Sealing composition in the form of a natural latex colloid and further additives, as described below, is then injected into the fault via the lower passage 38 by means of a positive displacement pump of the kind suitable for generating the higher pressures required.

[0028] The selected grout component of the sealing composition contains a major proportion of a latex emulsion or colloid, having a near uniform dispersion of polymeric particles having a particle size distribution with 100% of polymer particles having size less than 2 microns, notably having 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 particle size greater than 2 microns 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 at lower pressure and without the risk of undesirable hydrofracturing that a cement based sealing composition would indicate. A minor proportion of the grout component of the sealing composition was comprised of a lauric acid salt, ammonium laurate, as well as further selected additives as described further below.

[0029] By ‘major proportion’ of latex emulsion or colloid is intended an emulsion or colloid containing sufficient latex to form an effective seal once the emulsion or colloid is in situ within the passages to be sealed (here crack 30) and setting or coagulation is initiated. Typically, latex will be supplied in emulsion or colloidal suspension with water. The preferred latex is a natural rubber latex such as is readily available from a number of sources in various grades. Latex emulsions of purity greater than 50%, 60% and above are preferred for the grout component of the exemplary sealing composition.

[0030] As to the lauric acid component, ammonium laurate, this makes up less than 0.05 wt% of the sealing composition, here less than 0.03 wt% of the sealing composition with the lauric acid component being introduced through presence of a 9 2017100604 24 May 2017 coconut oil component in sufficient quantity which is then converted to ammonium laurate as described below. The lauric acid component improves the properties of the latex emulsion when being handled, specifically inhibiting the coagulation of the latex thus making it easier to pump into the passage being filled. The Applicant has also found that the presence of ammonium laurate supports the function of other coagulation inhibitors present within the sealing composition.

[0031] However, miscibility of the latex emulsion in water is substantially improved by converting the lauric acid into ammonium laurate by mixing the natural latex emulsion or colloid with an ammonia/water (ammonium hydroxide) solution. To that end, ammonia or a source of ammonia may also be included within the sealing composition. This also tends to maintain pH in the strongly alkaline range, pH above about 10 assisting transport of sealing composition to the sealing site without coagulation.

[0032] It has also been found that the addition of alkaline potassium hydroxide (KOH) (or any commercially available degreaser containing monobutyl ether, ethylene glycol and/or non-ionic surfactants) to the latex helps reduce the mechanical stability time (MST) and increases the activation of the latex.

[0033] The latex composition includes further selected components of a nature to reduce coagulation during pumping to the desired site (crack 30 and other fine porous portions of matrix 32 requiring sealing) and, if desirable, to increase the pressure resistance and friction resistance of the latex based sealing composition. Two additives, potassium hydroxide and detergent powder (for example the proprietary product KT powder which contains a mixture of sodium phosphates), are pre-mixed, preferably in the dry state (noting the requirement for fine grinding to meet the below 2 micron size criterion) and introduced to an industrially available natural rubber latex emulsion of greater than 50 wt% latex purity. In current practical usage, the latex was sourced at 60 to 80% purity. Natural or synthetic latex emulsions may be employed optionally at higher purities but this is dictated by economics. Further to natural latex selection, that polymer particles most advantageously have 100% polymer particles sized less than 2 microns and natural latex is sourced and treated, if required, to meet this requirement. 10 2017100604 24 May 2017 [0034] Further description of additives and preparation are contained in the Applicant’s Australian Patent Nos. 2009253842 and 2013266018, the contents of which are incorporated herein by reference.

[0035] In one example, prior to pumping into matrix 10 - as described below -approximately 1260 kg (6-210 Kg drums) of latex containing a small amount of coconut oil (sufficient to achieve a lauric acid concentration of about 0.03 wt% in the final sealing composition) was mixed with an additive mixture comprising 2.5 kg of KT powder (coagulation inhibitor), ground to the required sizing and 1-5kg of KOH. While this ratio of addition is ideally to be adhered to, it is possible that additions between 1 -20 kg KOH and 1 -3 kg KT powder will provide some level of advantage in the application of the latex. Required quantities for the sealing application will be determined following measurement of the hydraulic parameters as mentioned above. As the hydraulic parameters are monitored using a computer control and data acquisition unit, quantities may be re-calculated and further sealing composition made available as required. A suitable control and data acquisition unit is described in United States Patent No. 6801814, the contents of which are hereby incorporated herein by reference.

[0036] The latex/inhibitor mixture was mixed with water/ammonia solution in amount sufficient to convert lauric acid present in the latex to ammonium laurate at concentration favouring miscibility of the sealing composition with water. At this point, the polymer particle size distribution is as required above and no purposeful coagulation as would be required for sealing has occurred.

[0037] The sealing composition is pumped to provide sealing at crack 30. If necessary the sealing composition may be pumped to the sealing site following pumping of an alkaline solution, such as KOH solution, through the sealing site, to ‘stabilise’ the site by displacing or neutralising chemical species that may cause premature setting or coagulation.

[0038] Pumping at high pressures from 0.1 MPa to 20 MPa and higher will enable sealing of large cracks, such as crack 30, though the particle size constraints on the latex composition would enable significantly lower pressures than for cementation to be used economically. Particular advantage would be expected for sealing of 11 2017100604 24 May 2017 smaller dimension cracks, say under 160 microns or less in dimension, the flow characteristics of the latex composition in terms of particle size constraints and viscosity - as well as the nature of further components - facilitating permeation into these smaller cracks.

[0039] Coagulation or setting of the sealing composition may be done in a number of ways.

Example 1 [0040] As a result of site water analysis in area surrounding the theoretical mineshaft 14 finding that rate of coagulation or setting may be promoted above in situ coagulation rate, especially noting the presence of coagulation inhibitors in the latex emulsion or colloid, it was found appropriate for a coagulation accelerator in the form of dilute acid, for example hydrochloric acid, to be injected or pumped through upper passage 40, i.e downstream of the point where the sealing composition is injected, to promote coagulation thereof at an appropriate time after pumping of the latex. Faster coagulation rates may be achieved by increasing acid concentration and this may be appropriate where water leakage rates are high (potentially on the order of hundreds of litres water flow per minute) and a quick seal is required. Acid is pumped into matrix 32 using a separate pump to the pump used for delivering the above described latex emulsion to the sealing site, crack 30 and cracks of narrow dimension as above described. Coagulation starts when pH is reduced below 6.5 by contact with the neutral water of crack 30 itself and the coagulation accelerator. The pH at completion of coagulation is typically about 3.

[0041 ] The volume and concentration of hydrochloric acid accelerator - or any other accelerator such as citric acid or calcium chloride - to be introduced must be carefully controlled otherwise sealing composition may block entry passages such as 38 and 40 before cracks are sealed. Any number of passages may be drilled through the mineshaft lining 31 into the faulty area to achieve the sealing of crack 30 and the neighbouring narrow cracks as well as any other neighbouring leaks, fissures, voids or like faults. Passages may be drilled in a pattern or formation to achieve sealing of such leaks. In one example, the latex emulsion may be introduced to one first passage through another passage intersecting the first. 2017100604 24 May 2017 12

Example 2 [0042] In a further example, the latex based composition, as above described, is not pumped directly into the matrix 32 through the passages 38 and 40 as shown in Fig. 1 but the passage 38, or any further passages (some of which may have very small dimension, or less than 160 microns) may be drilled such as to have a larger diameter close to the mineshaft 14 over a length sufficient to accommodate a packer. The packer is then brought into communication with the reciprocating pump via a valve means. The pump and valve may be actuated by the computer control unit described above so that the latex based composition is pumped into the crack, fissure or similar fault until the desired pressure is attained (as monitored by the control unit). At this point the control unit may switch the valve off and disable the pump. The operation is then continued as many times as is necessary to achieve the desired sealing as determined following monitoring of selected hydraulic parameters such as water flow rate downstream of the seal barrier. Pumping of the latex composition at pressures up to 10 MPa was conducted without significant coagulation of latex and pumping at pressures up to 40 MPa can also be conducted where the wall structure has sufficient strength. Good permeation behaviour is also expected.

Example 3 [0043] The latex emulsion or colloid, with polymer particle size range as above described, in this example contains a curing agent that has the effect of lowering the pH of the emulsion gradually over a period of time to a pH that effects complete setting or coagulation of the grout component. pH lowering occurs by virtue of acid generation in situ of the combined latex emulsion/curing agent mixture. An equal mass of potassium permanganate solution (40 g/L) and ethanol - EtOH - (the combination acting as curing agent) was combined with moderately saline water. This combined liquid was added to 60% of a latex emulsion sold under the proprietary name NOH20). Ratio of curing agent to grout component was modified to effect variation in rate of coagulation/setting of the sealing composition. The results are shown in Table 1. 13 2017100604 24 May 2017

Table 1: Setting/coagulation of latex based grout composition with curing agent (potassium permanganate solution and ethanol) Wt% in curing agent Time since mixing to achieve solid mass Saline water KMn04 solution EtOH 96 2.0 2.0 Some solid after 20 mins; mostly solid after 16 hours 92 4.0 4.0 Some solid after 20 mins; mostly solid after 16 hours 92 8.0 none Partly solid after 30 mins; soft solid after 10 days 92 (non-saline water) 8.0 none Thick liquid after 10 days [0044] The combination of potassium permanganate solution and ethanol as a curing agent can be used to set or coagulate grout component by reacting with the grout component and lowering the pH of the grout component dispersion. A soft solid coagulate resulted from adding this curing agent to the grout component approximately 30 minutes after mixing.

Example 4: Potassium permanganate and alcohol as curing agent with 60% latex based grout composition [0045] A combination of potassium permanganate and alcohol was used to coagulate or set a 60% latex based grout component (sold under the proprietary name N0H20). Rate of coagulation was altered by using a different alcohol to ethanol in combination with the permanganate solution. For example, it was 2017100604 24 May 2017 14 postulated that adding an alcohol with more than one hydroxyl (OH) group instead of ethanol could alter the coagulation delay time or increase the rigidity of the grout once set. To test this, several different liquid polyols were combined with permanganate solution and then added to and mixed with 60% latex based grout component. The results of this testing are shown in Table 2. Best overall coagulation in the proportions tested was achieved using ethylene glycol in combination with permanganate solution.

Table 2: Coagulation of 60% latex based grout component with potassium permanganate solution and various alcohols 60% grout Curing agent components Time since mixing to achieve solid mass (mins) wt% in mix wt% KMn04 solution Alcohol type (2.0 wt% of mix) 92.0 6.0 Ethanol 30 (soft) 92.0 6.0 Polyethylene glycol 60 (soft) 92.0 6.0 Ethylene glycol 60 (paste) 92.0 6.0 Polyvinyl acetate 5 (soft) 92.0 6.0 50% ethanol/ethylene glycol 30 (soft); firmer solid after 10 days 92.0 6.0 50% ethanol/polyol mix 5 (soft) [0046] Modifications and variations to the method and composition of the present invention may be apparent to skilled readers of this disclosure. Such modifications and variations are deemed within the scope of the present invention.

Claims (5)

1. Claims:

   1. A method of limiting or reducing permeability of a matrix to limit or reduce liquid or gas inflow within a passage in the matrix, the method comprising delivering to said passage a coagulable polymer emulsion or colloid for contacting with at least one selected additive which interacts with said polymer emulsion or colloid to form a sealing composition barrier to reduce liquid or gas inflow within said passage, wherein said polymer 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.
2. 2. 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, wherein said polymer 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.
3. 3. The method of claim 1 or the sealing composition of claim 2 wherein said coagulable polymer emulsion or colloid is a latex emulsion or colloid, preferably a natural latex emulsion or colloid.
4. 4. The method of claim 1 or 3 or the sealing composition of claim 2 or 3 wherein said particle size distribution contains 100 wt% of particles with size below 5 microns, preferably size below 2 microns, preferably size about or below 1 micron.
5. 5. The method of any one of claims 1 to 4 being controlled by a control unit which monitors site parameters and actuates equipment, such as pumps and valves, to deliver said sealing composition to pre-determined locations according to monitored site parameters.