Treatment of contaminated water in clays and the like
First Claim
1. Procedure for treating contaminated groundwater, including the steps of:
- taking a sample of the ground containing the contaminated groundwater;
establishing the nature of the contaminant, and selecting a suitable treatment material;
proceeding with the following steps responsive to the selected treatment material being of the kind that will bring about a chemical breakdown of the contaminant when the contaminant is located, at a point of breakdown, in close physical proximity to the treatment material, being breakdown of the kind wherein;
(a) the contaminant is chemically converted into a relatively non-contaminating substance, (b) the concentration of the contaminant at the point of breakdown is substantially depleted by the breakdown, and (c) the effective concentration of the treatment material at the point of breakdown is unaffected or affected only very slowly by the breakdown;
determining the nature of the ground, and proceeding with the following steps responsive to a determination that the ground comprises large blocks of low permeability material (LPM), and the large LPM blocks are intercalated with cracks or other zones of higher permeability;
determining the concentration (CC-i) of the contaminant at an interior point of the LPM block, located a distance L from the nearest point on the boundary of the block;
carrying out measurements and calculations to determine the passive diffusion rate of the contaminant (PDR-C) in the LPM block, being the rate at which the concentration of the contaminant at the point changes over time as a function of the concentration gradient of the contaminant (CG-C) at that point;
providing conditions whereby passive diffusion of the contaminant towards the boundary of the block can take place;
proceeding with the following steps in response to a need to reduce the size, being the dimensions L, of the blocks;
providing a fracturing fluid, comprising a mixture of the treatment material with e carrier fluid;
establishing a concentration of treatment material (CTM-H) that can be injected into the fracks in the fracturing fluid, and forming the mixture to that concentration;
carrying out measurements and calculations to determine the extent of the treatment area, being the area of the contaminated LPM;
drilling boreholes at intervals over the treatment area;
fracturing the ground around the holes, so as to form fracks, by injecting the fracturing fluid under pressure into the boreholes;
spacing the boreholes a pitch distance apart over the treatment area such that the fracks overlap laterally;
establishing a mathematical model, based on the PDR-C, for enabling a theoretical prediction to be made of the relationship between the distance L and the time period taken for CC-i to drop to a safe concentration (CC-safe);
assigning an acceptable time period T for the CC-i to fall to CC-safe;
from the model, computing the distance L corresponding to that time period T;
forming a plurality of the fracks in the borehole, spaced a distance V apart, where V is no more than L;
after fracturing, maintaining passive conditions in the fracks at the point of breakdown;
wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the input of flow-inducing energy.
1 Assignment
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Accused Products
Abstract
The treatment system involves the use of hydrofracturing in drilled boreholes over the treatment area. The hydrofracturing fluid contains treatment material, of the kind that causes chemical breakdown of the contaminant. The breakdown leads to a contaminant concentration of zero in the hydrofracks, and therefore the contaminant diffuses towards the hydrofracks, where it is in turn broken down. Calculations and measurements indicate whether natural cracks in the ground are far enough apart to make hydrofracturing worthwhile. A formula indicates, from an assessment of diffusion coefficients, etc, whether the contaminant will be rendered safe within a given time period.
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Citations
24 Claims
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1. Procedure for treating contaminated groundwater, including the steps of:
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taking a sample of the ground containing the contaminated groundwater; establishing the nature of the contaminant, and selecting a suitable treatment material; proceeding with the following steps responsive to the selected treatment material being of the kind that will bring about a chemical breakdown of the contaminant when the contaminant is located, at a point of breakdown, in close physical proximity to the treatment material, being breakdown of the kind wherein;
(a) the contaminant is chemically converted into a relatively non-contaminating substance, (b) the concentration of the contaminant at the point of breakdown is substantially depleted by the breakdown, and (c) the effective concentration of the treatment material at the point of breakdown is unaffected or affected only very slowly by the breakdown;determining the nature of the ground, and proceeding with the following steps responsive to a determination that the ground comprises large blocks of low permeability material (LPM), and the large LPM blocks are intercalated with cracks or other zones of higher permeability; determining the concentration (CC-i) of the contaminant at an interior point of the LPM block, located a distance L from the nearest point on the boundary of the block; carrying out measurements and calculations to determine the passive diffusion rate of the contaminant (PDR-C) in the LPM block, being the rate at which the concentration of the contaminant at the point changes over time as a function of the concentration gradient of the contaminant (CG-C) at that point; providing conditions whereby passive diffusion of the contaminant towards the boundary of the block can take place; proceeding with the following steps in response to a need to reduce the size, being the dimensions L, of the blocks; providing a fracturing fluid, comprising a mixture of the treatment material with e carrier fluid; establishing a concentration of treatment material (CTM-H) that can be injected into the fracks in the fracturing fluid, and forming the mixture to that concentration; carrying out measurements and calculations to determine the extent of the treatment area, being the area of the contaminated LPM; drilling boreholes at intervals over the treatment area; fracturing the ground around the holes, so as to form fracks, by injecting the fracturing fluid under pressure into the boreholes; spacing the boreholes a pitch distance apart over the treatment area such that the fracks overlap laterally; establishing a mathematical model, based on the PDR-C, for enabling a theoretical prediction to be made of the relationship between the distance L and the time period taken for CC-i to drop to a safe concentration (CC-safe); assigning an acceptable time period T for the CC-i to fall to CC-safe; from the model, computing the distance L corresponding to that time period T; forming a plurality of the fracks in the borehole, spaced a distance V apart, where V is no more than L; after fracturing, maintaining passive conditions in the fracks at the point of breakdown; wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the input of flow-inducing energy. - View Dependent Claims (2, 3, 4, 5)
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6. Procedure for treating contaminated groundwater, including the steps of:
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establishing the nature of the contaminant in the ground, and selecting a suitable treatment material; determining the nature of the ground, and proceeding with the following steps in response to the ground comprising large blocks of low permeability material (LPM), the contaminant being present within the large LPM blocks, and the large LPM blocks are intercalated with cracks or other zones of higher permeability; providing conditions whereby passive diffusion of the contaminant from the interior towards the boundary of the block can take place; proceeding with the following steps in response to an assessed need to reduce the size of the blocks; providing a hydrofracturing liquid, comprising a mixture of the treatment material with a carrier liquid; establishing a concentration of treatment material that can be injected into the hydrofracks in the hydrofracturing fluid, and forming the mixture to that concentration; carrying out measurements and calculations to determine the extent of the treatment area, being the area of the ground containing the contaminated LPM; drilling boreholes at intervals over the treatment area; hydrofracturing the ground around the holes, so as to form hydrofracks, by injecting the hydrofracturing liquid under pressure from the surface into the boreholes; spacing the boreholes a pitch distance apart over the treatment area such that the hydrofracks overlap laterally; forming the hydrofracks in the boreholes a distance V apart; after hydrofracturing, and thereafter, maintaining passive conditions in the hydrofracks at the point of breakdown, wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the input of flow-inducing energy; and keeping the groundwater still and unmoving within the hydrofracks.
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7. Procedure for injecting a treatment material into a treatment area of ground containing a contaminant, and comprising low permeability material, wherein:
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the procedure includes the step of drilling boreholes at intervals over the treatment area; the procedure includes the step of providing hydrofracturing liquid, comprising a mixture of the treatment material with a carrier liquid; the procedure includes the step of hydrofracturing the ground around the holes, so as to form hydrofracks, by injecting the hydrofracturing liquid, which contains the treatment material, under pressure, into the boreholes; after hydrofracturing, and thereafter, maintaining passive conditions in the hydrofracks, wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the input of flow-inducing energy; and keeping the groundwater still and unmoving within the hydrofracks.
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8. Procedure for injecting a treatment material into a treatment area of ground containing a contaminant, and comprising low permeability material, wherein:
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the treatment material is in the liquid phase, which includes non-aqueous phase liquids and liquids dissolved in water; the procedure includes the step of drilling boreholes at intervals over the treatment area; the procedure includes the step of providing fracturing fluid, comprising a mixture of the treatment material with e carrier fluid; the procedure includes the step of fracturing the ground around the holes, so as to form fracks, by injecting the fracturing fluid, which contains the treatment material, under pressure, into the boreholes; after fracturing, and thereafter, maintaining passive conditions in the fracks, wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the Input of flow-inducing energy; and keeping the groundwater still and unmoving within the cracks. - View Dependent Claims (9, 10)
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11. Procedure for treating slowly-moving contaminated groundwater, comprising the steps of:
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establishing the nature of the contaminant in the ground, and selecting a suitable treatment material, the selected treatment material being of the kind that will bring about a chemical breakdown of the contaminant when the contaminant is located, at a point of breakdown, in close physical proximity to the treatment material, being breakdown of the kind wherein;
(a) the contaminant is chemically converted into a relatively non-contaminating substance, (b) the concentration of the contaminant at the point of breakdown is substantially depleted by the breakdown, and (c) the effective concentration of the treatment material at the point of breakdown is unaffected or affected only relatively slowly by the breakdown;determining the direction end speed of movement of a plume of the contaminant in the groundwater; establishing a treatment zone in the ground, in the path of the plume; determining the nature of the ground in the treatment zone, and proceeding with the following steps in response to the ground comprising large blocks of low permeability material (LPM); carrying out measurements and calculations to determine the extent of the treatment zone; drilling boreholes at intervals over the treatment zone; proceeding with the following steps in response to an assessed need to reduce the size of the blocks; providing a ground-fracturing fluid; fracturing the ground around the holes, so as to form fracks, by injecting the ground-fracturing fluid under pressure from the surface into the boreholes; spacing the boreholes a pitch distance apart over the treatment zone, such that the fracks overlap laterally; in each borehole, forming the fracks in the borehole a vertical distance V apart, the fracks comprising cracks, within the LPM, of relatively high permeability, whereby the large blocks of LPM are broken up; Injecting the treatment material, at a suitable concentration, into the fracks, whereby the treatment material is transferred into, and remains in, the fracks; after fracturing, and thereafter, maintaining passive conditions in the fracks at the point of breakdown, wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the input of flow-inducing energy; whereby the said contaminants in the slowly-moving groundwater moving naturally through the treatment zone are broken down.
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12. Procedure for treating contaminated groundwater, comprising the steps of:
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establishing the nature of the contaminant in the ground, and selecting a suitable treatment material, the selected treatment material being of the kind that will bring about a chemical breakdown of the contaminant when the contaminant is located, at a point of breakdown, in close physical proximity to the treatment material, being breakdown of the kind wherein;
(a) the contaminant is chemically converted into a relatively non-contaminating substance, (b) the concentration of the contaminant at the point of breakdown is substantially depleted by the breakdown, and (c) the effective concentration of the treatment material at the point of breakdown is unaffected or affected only relatively slowly by the breakdown;establishing a treatment zone; determining the nature of the ground in the treatment zone, and proceeding with the following steps In response to the ground comprising large blocks of low permeability material (LPM); carrying out measurements and calculations to determine the extent of the treatment zone;
drilling boreholes at intervals over the treatment zone;proceeding with the following steps In response to an assessed need to reduce the size of the blocks; providing a ground-fracturing fluid; fracturing the ground around the boreholes, so as to form fracks, by Injecting the ground-fracturing fluid under pressure from the surface into the boreholes; spacing the boreholes a pitch distance apart over the treatment zone, such that the fracks overlap laterally; in each borehole, forming the fracks in the borehole a vertical distance V apart, the fracks comprising cracks, within the LPM, of relatively high permeability, whereby the large blocks of LPM are broken up; injecting the treatment material, at a suitable concentration, into the fracks, whereby the treatment material is transferred into, and remains in, the fracks; after fracturing, end thereafter, maintaining passive conditions in the fracks at the point of breakdown, wherein the passive conditions are such that, under the passive conditions, passive diffusion of the contaminant towards the boundaries of the LPM blocks takes place, substantially without the input of flow-inducing energy; whereby the said contaminants in the groundwater in the treatment zone are broken down. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification