CN113857224B - Multiphase extraction soil restoration method after fracturing construction of soil layer microcirculation structure - Google Patents
Multiphase extraction soil restoration method after fracturing construction of soil layer microcirculation structure Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
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Abstract
The invention relates to the field of soil remediation, and discloses a multiphase extraction soil remediation method after a soil layer microcirculation structure is constructed by fracturing, which comprises the following steps: 1) Drilling at least two groups of fracturing well mechanisms on the soil area polluted by the organic matters, and injecting fracturing media into the fracturing soil in the soil area through one group of fracturing well mechanisms so as to form fracturing gaps around the fracturing well mechanisms; 2) Performing multiphase extraction through the remaining groups of fracturing well mechanisms to obtain an extract, wherein the number of groups of fracturing well mechanisms injected with the fracturing medium is smaller than the total number of groups of fracturing well mechanisms; the fracturing medium satisfies during injection into the soil region: the initial pressure is 0.2 Mpa-5.0 Mpa, and the flow speed of the fracturing medium in the fracturing well mechanism is 0.2-10 m/s; the injection amount of the fracturing medium per cubic meter of the soil area (5) is 5-10L. The method can greatly reduce the cost of soil remediation and shorten the remediation time.
Description
Technical Field
The invention relates to the field of soil treatment, in particular to a method for restoring multiphase extraction soil after a soil layer microcirculation structure is constructed by fracturing.
Background
Along with the improvement of national economic level and the transformation of production concept, the environmental protection index of enterprises such as petrochemical industry is continuously improved. Petrochemical enterprises have the unavoidable situation that part of crude oil and finished oil directly or indirectly flow into soil. Soil organic pollution mainly originates from leakage in petroleum development, transportation and storage processes, unreasonable discharge in chemical product processing and use, landfill leachate leakage, sudden chemical leakage and the like. The pollution of organic soil has profound effects, and has bad results, which lead to death of plants and microorganisms and even harm to human health. The organic matters can pollute the underground water along with the transfer of soil moisture.
At present, aiming at soil organic matter pollution, a multiphase extraction method is a relatively advanced restoration method, steam, hot air and the like are adopted in the multiphase extraction process to promote volatilization of organic matters in soil, and then gas is extracted from the soil in the same extraction well or adjacent extraction wells to carry out innocent treatment, as reported in CN108339842A, a soil gas phase extraction system and a method based on combined injection of water vapor and hot air can act on a shaft wall and a soil layer shallow around the shaft wall, but when soil viscosity is large and soil air permeability is poor, the coverage area of the extraction well is small, so that the extraction effect is greatly influenced.
However, the permeability of contaminated soil tends to be greatly reduced, sometimes even with severe hardening, resulting in the difficulty of multiphase extraction between extraction wells to produce the desired effect of multiphase extraction.
In addition, since the soil area where each extraction well can act is small, so that a great number of extraction wells are needed for soil remediation, the conventional multiphase extraction method has the defects of time consumption, labor consumption and poor effect.
Disclosure of Invention
The invention aims to solve the problems of poor extraction effect and high extraction well number requirement existing in the existing multiphase extraction method.
In order to achieve the above purpose, the invention provides a method for restoring multiphase extraction soil after fracturing to construct a soil layer microcirculation structure, which comprises the following steps:
1) Drilling at least two groups of fracturing well mechanisms on the soil area polluted by the organic matters, injecting fracturing medium into the fracturing soil in the soil area through at least one group of fracturing well mechanisms so as to form fracturing gaps around the fracturing well mechanisms;
2) Performing multiphase extraction through the remaining groups of fracturing well mechanisms to obtain an extract;
wherein the number of groups of the fracturing well mechanisms into which the fracturing medium is injected is less than the total number of groups of the fracturing well mechanisms; the fracturing medium satisfies during injection into the soil region: the initial pressure is 0.2 Mpa-2.0 Mpa, and the flow speed of the fracturing medium in the fracturing well mechanism is 0.2-10 m/s; the injection amount of the fracturing medium per cubic meter of the soil area is 1-10L.
Preferably, the fracturing well unit comprises at least a 2-stage fracturing well, and the step of drilling the fracturing well unit in step 1) comprises: and drilling a next stage of fracturing well from the well wall of the previous stage.
Preferably, the fracturing well unit comprises a primary well and a secondary well, and the step of drilling the fracturing well unit in step 1) comprises: the secondary well is drilled from below and in the middle of the primary well.
Preferably, the step of drilling at least one set of frac well means in step 1) further comprises: the fracturing well mechanism is reinforced in a manner that a sleeve is preferably arranged on the inner wall of the fracturing well mechanism.
Preferably, the step of drilling the fracturing well unit in step 1) further comprises: drilling a fracturing medium discharge hole in the well wall of the fracturing well mechanism.
Preferably, step 1) further comprises: and arranging a fracturing nozzle on the fracturing medium discharge hole so that the fracturing medium can be injected into the soil area through the fracturing nozzle.
Preferably, step 1) further comprises: a fracturing direction control unit, preferably a nozzle, is provided in the soil region.
Preferably, step 1) further comprises: and arranging a fracturing unit at the top of the fracturing well mechanism, and injecting the fracturing medium into the fracturing well mechanism by the fracturing unit.
Preferably, the drilling step is performed in one pass and/or in multiple passes.
Preferably, the density of the fracturing medium discharge holes on the fracturing well mechanism is 1-10 per cubic meter of the soil area (5), and the aperture of the fracturing medium discharge holes is 0.1-10 mm.
Preferably, the number of the fracturing well mechanisms is at least two, and the distance between two adjacent fracturing well mechanisms is 5-10 m.
Preferably, the average width of the fracturing gap is 0.1-10 mm by controlling the injection conditions of the fracturing medium.
Preferably, the fracturing medium comprises at least one of a liquid, a gas and a gel, preferably guanidine gum and/or air.
Preferably, the fracturing medium further comprises a particulate material.
Preferably, the particulate material has at least one of adsorption, absorption and chemical reaction capability.
Preferably, after the fracturing medium completes fracturing the soil, the method further comprises draining the fracturing medium out of the soil or leaving the fracturing medium in the soil.
Preferably, at least 2 adjacent fracturing gaps are communicated to form a gap grid.
Preferably, the number of the fracturing well units is at least three, the method further comprising: injecting a fracturing medium into the fracturing soil in the soil area through at least one group of fracturing well mechanisms, and performing multiphase extraction on the fracturing soil through the fracturing well mechanisms injected with the fracturing medium.
Preferably, step 2) comprises: before the multiphase extraction is carried out, the step 2) further comprises: an implant is injected into the fracturing well mechanism.
Preferably, the injectate is selected from at least one of steam, gas, leacheate, and colloid.
Preferably, the implant is a high temperature gas at 120-200 ℃.
Preferably, the injectate is steam at 130-140 ℃.
Preferably, the injection rate of the implant is 8-20m 3 /h。
Preferably at 100m 3 The injection amount of the high-temperature gas is 1-5m based on the soil region 5 3 。
Preferably, the multi-phase extraction is performed under negative pressure or the multi-phase extraction is performed under the pressure of the injectant itself.
Preferably, the multiphase extraction is carried out at a pressure of-0.1 Mpa to-0.01 Mpa.
Preferably, the fracturing well mechanism for injecting the injection object is an injection well, and the fracturing well mechanism for carrying out the multiphase extraction is an extraction well; the injection well and the extraction well are the same fracturing well mechanism and/or the injection well and the extraction well are different fracturing well mechanisms.
Preferably, the injection well and extraction well are the same fracturing well unit, and after the injection of the injectant is completed, the method further comprises: sealing the injection well, and sequentially connecting and extracting the injection well and the extraction mechanism.
Preferably, the injection well and extraction well are different said fracturing well mechanisms, the method further comprising: and injecting the injection object into the injection well, and sequentially connecting and extracting an extraction mechanism with the extraction well.
Preferably, the implant is injected into the injection well by an injection unit.
Preferably, the time for a single said multi-phase extraction is 20-30 hours.
Preferably, the total number of said multiphase extractions is between 5 and 50, preferably between 5 and 10.
Preferably, the total number of times of the multi-phase extraction is controlled so that the content of the contaminating organic matters in the soil area after the multi-phase extraction is 2-100mg/Kg.
Preferably, the method further comprises: the extract is subjected to a post-treatment.
Preferably, the post-treatment comprises: and separating the extract to obtain organic gas, sediment and wastewater, and performing harmless treatment on the organic gas.
Preferably, the post-treatment comprises: and (3) carrying out water washing and cooling on the extract, carrying out three-phase separation in a three-phase separator to obtain organic gas, sediment and wastewater, and then collecting the organic gas into a waste gas treatment device for harmless treatment.
Preferably, the innocent treatment is selected from at least one of absorption, adsorption, water washing, alkali washing, membrane separation, catalytic oxidation, regenerative combustion, direct combustion, plasma technology treatment, chemical oxidation and microorganism treatment.
According to the technical scheme, the method provided by the invention has the advantages that the soil around at least one group of fracturing well mechanisms is fractured through the fracturing medium to form fracturing gaps, the fracturing medium is not injected into the remaining groups of fracturing well mechanisms, and a circulation channel can be formed by means of the fracturing gaps in the multiphase extraction process so as to improve the circulation efficiency of the material flowing to the remaining groups of fracturing well mechanisms; in particular, the inventors optimize the mass flow efficiency by controlling the pressure, rate and injection amount of the fracturing medium. Therefore, in the multiphase extraction process, the polluted organic matters can be desorbed with soil particles under the negative pressure condition, and then enter the circulation channel to be extracted.
Meanwhile, the existence of the circulation channel can increase the soil area of each extraction well, so that the number of the extraction wells can be reduced, and the cost is greatly reduced. Therefore, the method can greatly reduce the cost of soil remediation and shorten the remediation time.
In addition, in the invention, the injection and in-situ extraction of the fracturing medium are not carried out in the same fracturing well mechanism, but different shafts are communicated through fracturing gaps by a shaft and transverse fracturing method, so as to form a network structure inside the soil. The preferred extraction method is as follows: the method can inject air, steam, leacheate and other mediums into one shaft, and extract the mediums from other shafts, so that the effect is better than that of directly extracting the mediums in a single extraction well.
Compared with the existing in-situ extraction mode, the in-situ extraction (in-situ extraction is only for soil, only the extraction which is carried out without digging the soil is in-situ extraction), has high efficiency and large coverage area of an extraction well, and can promote the effect by injecting steam, nitrogen, hot air and the like in the extraction process.
Drawings
FIG. 1 is a schematic diagram of the operation of a preferred embodiment of frac soil in a method for multiphase extraction soil remediation after frac construction of a soil layer microcirculation structure provided by the invention;
FIG. 2 is a schematic diagram of the operation of a drilling and fracturing well mechanism and a preferred embodiment of multiphase extraction in the method for multiphase extraction soil remediation after fracturing a constructed soil layer microcirculation structure provided by the invention;
FIG. 3 is a state diagram of the particulate material in a fracturing gap provided by the present invention;
fig. 4 is an operation schematic diagram of a well drilling and fracturing mechanism in the method for repairing multiphase extraction soil after fracturing and constructing a soil layer microcirculation structure.
Description of the reference numerals
1. Injection unit 2, extraction well
3. Injection well 4, particulate material
5. Soil region 7, three-phase separator
8. Exhaust gas treatment device 9 and injection article
10. Extract 11, discharge line
12. Primary well 13 and secondary well
14. Fracturing gap 16 and fracturing nozzle
21. Fracturing unit
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In the present invention, unless otherwise indicated, the terms "top" and "bottom" and the like are used merely to denote orientations of the terms in a normal use state or are commonly understood by those skilled in the art, and should not be construed as limitations of the terms.
The invention provides a method for restoring multiphase extraction soil after fracturing construction of a soil layer microcirculation structure, which is shown in figures 1-2 and 4 and comprises the following steps:
1) Drilling at least two groups of fracturing well mechanisms on the soil area 5 polluted by the organic matters, injecting fracturing medium into the fracturing soil in the soil area 5 through at least one group of fracturing well mechanisms so as to form fracturing gaps 14 around the fracturing well mechanisms;
2) Performing multiphase extraction through the remaining groups of fracturing well mechanisms to obtain an extract;
wherein the number of groups of the fracturing well mechanisms into which the fracturing medium is injected is less than the total number of groups of the fracturing well mechanisms; the fracturing medium satisfies during injection into the soil region: the initial pressure is 0.2 Mpa-5.0 Mpa, and the flow speed of the fracturing medium in the fracturing well mechanism is 0.2-10 m/s; the injection amount of the fracturing medium per cubic meter of the soil area 5 is 1-10L.
In the above method, in order to increase the application range of the method, it is preferable that the contaminated organic matter when the soil region 5 is not repaired is selected from at least one of benzene compounds, gasoline and diesel oil, carbon tetrachloride, and other organic matter.
Meanwhile, in order to further secure the extraction effect of the method, it is preferable that the content of the contaminating organic matter per Kg of the soil region 5 is 5 to 100g when the soil region 5 is not repaired.
In the present invention, in order to further enhance the multiphase extraction effect, preferably, the fracturing well means comprises at least 2-stage fracturing well, and the step of drilling the fracturing well means in step 1) comprises: drilling a next-stage fracturing well from the well wall of the previous stage; thus, by providing the fracturing well mechanism to include at least 2 stages of fracturing wells, the fracturing medium is sufficiently contacted with the soil to allow the density of the fracturing slots 14 to be sufficiently high to allow for more optimal results of multi-phase extraction. Wherein, from the two aspects of cost and multiphase extraction effect comprehensive, preferably, the fracturing well mechanism comprises a primary well 12 and a secondary well 13, and the step of drilling the fracturing well mechanism in the step 1) comprises the following steps: a secondary well 13 is drilled from below and in the middle of the primary well 12.
In the present invention, in order to further improve the structural stability of the fracturing well units, preferably, the step of drilling at least one group of fracturing well units in step 1) further comprises: the fracturing well mechanism is reinforced in a manner that a sleeve is preferably arranged on the inner wall of the fracturing well mechanism. Therefore, the structural stability of the fracturing well mechanism can be improved in a reinforcing mode, and further the orderly progress of fracturing soil and multiphase extraction is effectively ensured.
In the present invention, in order to further improve the formation efficiency of the fracturing gap 14, preferably, the step of drilling the fracturing well mechanism in step 1) further includes: and drilling a fracturing medium discharge hole on the well wall of the fracturing well mechanism in a blasting pulse mode. The fracturing medium is instantaneously discharged and sprayed out from the medium under the high pressure condition and rapidly spreads around to form blasting pulse.
In the present invention, in order to further improve the formation efficiency of the fracturing gap 14, preferably, step 1) further includes: disposing a fracturing nozzle 16 over the fracturing medium exit aperture to enable fracturing medium to be injected into the soil region 5 through the fracturing nozzle 16; the formation of the fracturing gaps 14 in the soil in the form of blasting pulses by means of the fracturing nozzles 16 is thereby enabled, which greatly improves the efficiency of the formation of the fracturing gaps 14.
In the present invention, in the process of fracturing the soil, the fracturing slits 14 can be formed by means of micro-slits in the soil, but in order to obtain directional fracturing slits 14, so as to facilitate the regulation of the direction of the flow channel, preferably, step 1) further comprises: arranging a fracturing direction control unit in the soil area 5, wherein the fracturing direction control unit is preferably a nozzle; this enables the directional formation of the fracturing gap 14 by the nozzle.
In addition, in the present invention, the fracturing medium can be directly injected into the fracturing well mechanism, but in order to further facilitate uniform injection while effectively pressurizing the fracturing medium, preferably, step 1) further includes: setting a fracturing unit 21 on the top of a fracturing well mechanism, and injecting a fracturing medium into the fracturing well mechanism by the fracturing unit 21; thus, the fracturing unit 21 on the one hand serves to pressurise and on the other hand can serve to transport the fracturing medium.
In the present invention, it is preferable that the drilling step is completed at one time and/or intermittently performed a plurality of times in consideration of the specific progress of the construction and the difficulty level of the construction.
In the present invention, in order to further enhance the effect of the multiphase extraction, it is preferable that the density of the fracturing medium discharge holes on the fracturing well mechanism is 1 to 20 per cubic meter of the soil area 5, and the aperture of the fracturing medium discharge holes is 0.1 to 10mm.
In the present invention, from the viewpoint of both the effect of the multiphase extraction and the operation cost, it is preferable that the number of the fracturing well units is at least two, and the distance between the adjacent two fracturing well units is 5 to 10m. The distance between two adjacent fracturing well mechanisms is the distance between the circle centers of the top parts of the two adjacent fracturing well mechanisms.
In the present invention, in order to further enhance the effect of the multi-phase extraction, it is preferable to control the injection condition of the fracturing medium so that the average width of the fracturing gap 14 is 0.1 to 10mm.
In the present invention, in order to further enhance the fracturing effect, preferably, the fracturing medium includes at least one of a liquid, a gas, and a colloid, more preferably guanidine gum and/or air.
In the above method, in order to increase the mechanical strength of the fracturing gap 14, the fracturing medium preferably further comprises a particulate material; as shown in fig. 3, the particulate material helps to fill in the cracks after fracturing, avoiding collapse of the cracks after fracturing and during extraction. Wherein, in order to further promote the conversion and movement of organic matter in the soil, it is preferable that the particulate material has at least one of adsorption, absorption and chemical reaction-enabling function; preferably, the particulate material has an average particle size of 1mm to 5mm; more preferably, the amount of particulate matter used is 1-10kg per cubic meter of said soil area 5.
In the present invention, the process of fracturing the soil can be completed once or intermittently performed several times, and it is preferable that the method further comprises discharging the fracturing medium out of the soil or leaving the fracturing medium in the soil after the fracturing medium completes fracturing the soil in consideration of the specific circumstances of the construction.
In the process of fracturing the soil, cracks are generated in soil layers among different fracturing well mechanisms, and finally the fractured cracks are interwoven or mutually close to form mutually communicated circulation channels or mutually close semi-communication networks, so that the possibility is created for circulation of substances in the soil. To further facilitate material flow, preferably, at least 2 adjacent fracturing slots 14 are in communication to form a slotted grid.
Of course, in addition to the above-described flow channels, it is preferable that two adjacent fracturing slots 14 are not communicated with each other in order to further enhance the multiphase extraction effect. However, under the pressure of multiphase extraction, the fully communicated flow channels between the fracturing slits 14 are finally formed, so that the effect of multiphase extraction is not affected, and the fracturing cost is reduced.
In order to further improve the efficiency of multiphase extraction on the basis of the above embodiment, preferably, the number of the fracturing well units is at least three, and the method further includes: a fracturing medium is injected into the fractured soil in the soil zone 5 through at least one group of the fracturing well mechanisms, and multiphase extraction is performed through the fracturing well mechanisms injected with the fracturing medium. Therefore, the in-situ extraction can be performed after the third group of fracturing well mechanisms complete the soil fracturing, so that the extraction efficiency is further accelerated.
In the present invention, in order to further enhance the multiphase extraction effect, preferably, the fracturing well means for injecting the fracturing medium into the soil zone 5 is a fracturing well, the method further comprising: completing fracturing soil, and performing multiphase extraction through the fracturing well; namely, the fracturing well mechanism is used as an injection well 3, an injection object 9 is injected into the injection well 3, then the fracturing well mechanism is used as an extraction well 2, and the extraction well 2 is subjected to multiphase extraction to obtain an extract 10. The desorption process of the organic matters and soil particles can be accelerated after the injection 9 is fully contacted with the soil, and the extraction effect can be greatly improved by re-extraction on the basis. Of course, extraction can be performed without using the implant 9, and this embodiment is as follows: after the fracturing medium is subjected to fracturing, directly extracting by virtue of the fracturing medium; or the fracturing medium is directly subjected to direct multiphase extraction on the soil region 5 after being discharged out of the soil, negative pressure is generated in the extraction process, and polluted organic matters can be desorbed from soil particles under the negative pressure condition to form gas phase to be extracted, so that the injection 9 is saved, the operation flow is further shortened, and the cost is reduced.
In the present invention, the frac well means can be arranged in any arrangement in the contaminated soil area, with the placement of the injection wells and extraction wells being such that the circulation network extends throughout the contaminated soil space as much as possible.
In the present invention, in order to further enhance the injection effect of the injection material 9 and thereby enable the injection material 9 to sufficiently fill the fracturing gaps 14, preferably, the injection material 9 is selected from at least one of steam, gas, leacheate, and colloid; more preferably, the implant is a high temperature gas at 120 ℃ to 200 ℃; further preferably, the injectate 9 is steam at 130-140 ℃.
In the present invention, for the further promotionHigh injection effect of the implant 9, preferably the implant 9 has an injection rate of 8-20m 3 /h; more preferably at 100m 3 The injection amount of the high-temperature gas is 1-5m based on the soil region 5 3 。
In the present invention, in order to further enhance the effect of the multi-phase extraction, it is preferable that the multi-phase extraction is performed under a negative pressure or the multi-phase extraction is performed under a pressure of the implant 9 itself; more preferably, the heterogeneous extraction is carried out at a pressure of-0.1 MPa to-0.01 MPa.
In the present invention, the fracturing well means for injecting the injector 9 is an injection well 3, and the fracturing well means for performing the multiphase extraction is an extraction well 2; in the present invention, any one or more primary wells may be selected as the injection well, and any one or more primary wells may be selected as the extraction well. For soil areas 5 of different topography, it is preferred that the injection well 3 and the extraction well 2 are the same fracturing well means and/or that the injection well 3 and the extraction well 2 are different fracturing well means. Wherein, as long as the number of the fracturing well mechanisms is more than 3, one implementation mode is carried out simultaneously, and specifically, the injection well 3 and the extraction well 2 are both first fracturing well mechanisms; another embodiment can also be performed simultaneously: the injection well 3 and the extraction well 2 adopt a second fracturing well mechanism and a third fracturing well mechanism respectively; thereby effectively improving the extraction effect and efficiency.
In the above embodiment, in order to further improve the extraction effect, it is preferable that the injection well 3 and the extraction well 2 are the same fracturing well mechanism, and after the injection of the injection material 9 is completed, the method further includes: the injection well 3 is sealed, and then the injection well 3 and the extraction mechanism are connected in sequence to perform extraction.
Similarly, to further enhance the extraction effect, it is preferred that the injection well 3 and the extraction well 2 are different fracturing well units, the method further comprising: the injection material 9 is injected into the injection well 3, and then the extraction mechanism and the extraction well 2 are connected in sequence to perform extraction.
In the present invention, in order to facilitate pressurization and conveyance of the implant 9, it is preferable that the implant 9 is injected into the injection well 3 through the injection unit 1. Thus, the injection unit 1 can perform both pressurization and transportation functions.
In the present invention, in order to further improve the extraction effect, preferably, the time of single multi-phase extraction is 20 to 30 hours; preferably, the total number of multi-phase extractions is from 5 to 50, preferably from 5 to 10. More preferably, the total number of multi-phase extractions is controlled such that the content of contaminating organic matter in the soil area 5 after multi-phase extraction is 2-100mg/Kg.
In the present invention, in order to make the method more environmentally friendly, it is preferable that the method further comprises: the extract 10 is subjected to a post-treatment. Preferably, the post-treatment comprises: the extract 10 is separated to obtain organic gas, sediment and wastewater, and then the organic gas is subjected to harmless treatment.
In order to further improve the effects of three-phase separation and innocent treatment, the post-treatment preferably includes: the extract 10 is subjected to water washing and cooling, and is subjected to three-phase separation in a three-phase separator 7 to obtain organic gas, sediment and wastewater, and then the organic gas is collected into a waste gas treatment device 8 for innocent treatment;
in addition, in order to further enhance the effect of the innocent treatment, it is preferable that the innocent treatment is at least one selected from the group consisting of absorption, adsorption, water washing, alkali washing, membrane separation, catalytic oxidation, regenerative combustion, direct combustion, plasma technology treatment, chemical oxidation, and microbial treatment.
The invention will be described in detail below by way of examples. In the examples below, the detection of the content of contaminating organic compounds was determined by the post-extraction gas chromatography test method. Soil zone 5 is an experimental soil module that satisfies the following conditions: the total content of organic pollutants is 5g/kg, and the organic pollutants are formed by 10: 9: toluene in 1 weight ratio: hexane: methyl mercaptan; the soil depth is 15m; the soil is clay.
Example 1
(1) Drilling an extraction well: as shown in fig. 4 (only one primary well 12 is depicted in fig. 4, the other primary wells 12 have been omitted for simplicity of the drawing), at least two primary wells 12 are drilled on the soil area 5; the distance between adjacent primary wells 12 is 5m.
(2) Fracturing soil gas: as shown in fig. 1 and 2, the wall of the extraction well of step (1) is drilled at an angle of 90 °, and the secondary well 13 is obtained by transverse fracturing with guanidine gum as a fracturing fluid.
(3) And (3) construction of a circulation network: as shown in fig. 2, a fracturing medium discharge hole is drilled on the wall of the secondary well 13, and a blasting pulse mode is adopted in the secondary well 13 to impact the soil layer, so that the soil is cracked by pulse gas, and gaps and a gap network are generated in the soil. The fracturing medium adopted during impact is air, and the process constructs a gap network for connecting two longitudinal extraction wells. Wherein the fracturing medium, during injection into the soil zone 5, satisfies: the initial pressure is 1.5Mpa, and the flow rate of the fracturing medium in the primary well is 2m/s; the density of the fracturing medium discharge holes on the fracturing well mechanism is 2 per m 3 The injection amount of the fracturing medium in the soil area 5 per cubic meter is 10L, and the aperture of the fracturing medium discharge hole is 1mm; the average width of the fracture gap 14 was 2.8mm.
(4) Multiphase extraction: as shown in FIG. 2, one of the primary wells was used as an injection well at 10m 3 A flow rate of/h, and injecting high-temperature steam at 135 ℃ into the well (the injection amount of the high-temperature steam per cubic meter of the soil region 5 is 0.01m 3 ). The other primary well is connected with an extraction device, and the polluted soil layer is subjected to negative pressure extraction operation at the extraction well head under the pressure of-0.09 Mpa. The organic matters blown by the injected steam are extracted from the soil, the extracted mixture of waste gas and waste liquid enters a three-phase separator 7 for three-phase separation, and organic matters gas, sediment and waste water are obtained and discharged through a discharge pipeline 11.
(5) And (3) subsequent treatment: the extracted waste gas is treated by adopting a coupling technology of combining membrane separation and adsorption, and then is discharged after reaching the standard.
(6) Repeating the operation of the step (3) and the step (4) for 5 times, carrying out multiphase extraction, and carrying out 24 hours of each extraction, wherein the content of organic pollutants in the restored soil is 79mg/Kg.
Example 2
The procedure of example 1 was followed, except that the distance between two adjacent frac well means was 8m, and the frac medium, during injection into the soil zone 5, satisfied: the initial pressure is 5Mpa, the flow speed of the fracturing medium in the fracturing well mechanism is 10m/s, and the density of the fracturing medium discharge holes on the fracturing well mechanism is 10 per m 3 The aperture of the fracturing medium discharge hole is 1mm, the injection amount of the fracturing medium in each cubic meter of the soil area 5 is 2L, and the average width of the fracturing gap 14 is 1mm.
Finally, the content of organic pollutants in the restored soil is 56mg/Kg through detection.
Example 3
The procedure of example 1 was followed, except that the distance between two adjacent frac well means was 10m, and the frac medium satisfied during injection into the soil zone 5: the initial pressure is 0.5Mpa, the flow rate of the fracturing medium in the fracturing well mechanism is 0.2m/s, and the density of the fracturing medium discharge holes on the fracturing well mechanism is 20 per m 3 The aperture of the fracturing medium discharge hole is 10mm, the injection amount of the fracturing medium in each cubic meter of the soil area 5 is 8L, and the average width of the fracturing gap 14 is 2.8mm.
Finally, the content of organic pollutants in the restored soil is 33mg/Kg through detection.
Example 4
The procedure of example 1 was followed, except that in step (4), high-temperature steam of 135℃was not injected into one of the injection wells, but the other extraction well was directly connected to the extraction apparatus to conduct multi-phase extraction.
Finally, the content of organic pollutants in the restored soil is 1158mg/Kg through detection.
Example 5
The procedure of example 1 was followed, except that as shown in FIG. 3, the fracturing medium was doped with particulate matter 4 (sand) having an average particle size of 2mm; the injection amount of the particulate matter into the soil region 5 was 5Kg/m 3 。
Finally, the content of organic pollutants in the restored soil is 8mg/Kg through detection.
Comparative example 1
The procedure of example 1 was followed, except that step (2) was not performed, and the distance between two adjacent frac well mechanisms was 12m.
After the operation is finished, the content of organic pollutants in the restored soil is 2570 mg/Kg through detection.
Comparative example 2
The procedure of example 1 was followed, except that the fracturing medium satisfied during injection into the soil zone 5: the initial pressure was 0.5Mpa, the flow rate of the fracturing medium in the fracturing well mechanism was 12m/s, and the injection amount of the fracturing medium per cubic meter of the soil area 5 was 1L.
After the operation is finished, the content of organic pollutants in the restored soil is 1541mg/Kg through detection. Thus, the injection amount of the fracturing medium is too small, the fracturing effect is poor, and the extraction effect is poor.
Comparative example 3
The procedure of example 1 was followed, except that the fracturing medium satisfied during injection into the soil zone 5: the initial pressure was 0.1Mpa, the flow rate of the fracturing medium in the fracturing well mechanism was 1.0m/s, and the injection amount of the fracturing medium per cubic meter of the soil area 5 was 12L.
After the operation is finished, the content of organic pollutants in the restored soil is 1404mg/Kg through detection. It can be seen that the injection effect is poor due to too small pressure, resulting in poor extraction effect.
Comparative example 4
The process of example 1 was followed, except that the density of fracturing medium exit holes on the fracturing well mechanism was 1/m 3 And the aperture of the fracturing medium discharge hole is 12mm.
After the operation is finished, the content of organic pollutants in the restored soil is 1450mg/Kg through detection. Therefore, the pressure mechanism has low density, the fracturing aperture is not proper, the fracturing effect is poor, and the expected effect cannot be achieved after extraction.
Comparative example 5
The process of example 1 was followed, except that the density of fracturing medium exit holes on the fracturing well unit was 20 per m 3 And the aperture of the fracturing medium discharge hole is 0.01mm in soil.
After the operation is finished, the content of organic pollutants in the restored soil is 1290mg/Kg through detection. It can be seen that too small a hole diameter of the discharge hole results in poor fracturing effect.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (33)
1. A method for multi-phase extraction soil remediation after fracturing a constructed soil layer microcirculation structure, which is characterized by comprising the following steps:
1) Drilling at least two groups of fracturing well mechanisms on the soil area (5) polluted by the organic matters, injecting fracturing media into the soil in the soil area (5) through at least one group of fracturing well mechanisms so as to form fracturing gaps (14) around the fracturing well mechanisms;
2) Injecting an injector (9) into the fracturing well mechanism, and performing multiphase extraction through the remaining groups of fracturing well mechanisms to obtain an extract (10); the injection material is steam at 130-140deg.C, and the injection rate of the injection material (9) is 8-20m 3 /h；
Wherein the number of groups of the fracturing well mechanisms into which the fracturing medium is injected is less than the total number of groups of the fracturing well mechanisms; the fracturing medium, during injection into the soil zone (5), satisfies: the initial pressure is 0.2 Mpa-5.0 Mpa, and the flow speed of the fracturing medium in the fracturing well mechanism is 0.2-10 m/s; the injection amount of the fracturing medium per cubic meter of the soil area (5) is 1-10L;
the density of the fracturing medium discharge holes on the fracturing well mechanism is 1-20 per cubic meter of the soil area (5), and the aperture of the fracturing medium discharge holes is 0.1-10 mm.
2. The method of claim 1, wherein the frac well means comprises at least a grade 2 frac well, and the step of drilling the frac well means in step 1) comprises: and drilling a next stage of fracturing well from the well wall of the previous stage.
3. The method according to claim 1 or 2, wherein the fracturing well unit comprises a primary well (12) and a secondary well (13), and the step of drilling the fracturing well unit in step 1) comprises: the secondary well (13) is drilled from below the middle of the primary well (12).
4. The method of claim 1 or 2, wherein the step of drilling at least one set of frac well means in step 1) further comprises: and reinforcing the fracturing well mechanism.
5. The method of claim 4, wherein the strengthening is by disposing a casing on an inner wall of the frac well mechanism.
6. The method of claim 1 or 2, wherein the step of drilling the fracking well mechanism in step 1) further comprises: drilling a fracturing medium discharge hole in the well wall of the fracturing well mechanism.
7. The method according to claim 1 or 2, wherein step 1) further comprises: a fracturing nozzle (16) is provided on the fracturing medium discharge aperture to enable the fracturing medium to be injected into the soil region (5) through the fracturing nozzle (16).
8. The method according to claim 1 or 2, wherein step 1) further comprises: and arranging a fracturing direction control unit in the soil area (5), wherein the fracturing direction control unit is a nozzle.
9. The method according to claim 1 or 2, wherein step 1) further comprises: a fracturing unit (21) is arranged on top of the fracturing well mechanism, and the fracturing unit (21) injects the fracturing medium into the fracturing well mechanism.
10. The method according to claim 1 or 2, wherein the drilling step is performed in one pass and/or in multiple pauses.
11. The method according to claim 1 or 2, wherein the number of fracturing well units is at least two, and the distance between two adjacent fracturing well units is 5-10 m.
12. A method according to claim 1 or 2, characterized in that the average width of the fracturing gap (14) is made to be 0.1-10 mm by controlling the injection conditions of the fracturing medium.
13. The method of claim 1 or 2, wherein the fracturing medium comprises at least one of a liquid, a gas, and a colloid.
14. The method of claim 1 or 2, wherein the fracturing medium is guanidine gum and/or air.
15. The method of claim 13, wherein the fracturing medium further comprises a particulate material.
16. The method of claim 15, wherein the particulate material has at least one of adsorption, absorption, and chemical reaction capability.
17. The method of claim 1 or 2, wherein after the fracturing medium completes fracturing the soil, the method further comprises draining the fracturing medium out of the soil or leaving the fracturing medium in the soil.
18. A method according to claim 1 or 2, characterized in that the communication between adjacent at least 2 of said fracturing slits (14) forms a slit grid.
19. The method of claim 1 or 2, wherein the number of frac well mechanisms is at least three, the method further comprising: injecting a fracturing medium into the fracturing soil in the soil area (5) through at least one group of fracturing well mechanisms, and performing multiphase extraction on the fracturing soil through the fracturing well mechanisms injected with the fracturing medium.
20. The method according to claim 1, characterized in that the multiphase extraction is carried out under negative pressure or the multiphase extraction is carried out under self-contained pressure of the injectant (9).
21. The process according to claim 1, wherein the multiphase extraction is carried out at a pressure of-0.1 Mpa to-0.01 Mpa.
22. The method according to claim 1, characterized in that the fracturing well means into which the injectant (9) is injected is an injection well (3) and the fracturing well means into which the multiphase extraction is performed is an extraction well (2); the injection well (3) and the extraction well (2) are the same fracturing well mechanism, and/or the injection well (3) and the extraction well (2) are different fracturing well mechanisms.
23. The method according to claim 22, wherein the injection well (3) and extraction well (2) are the same fracturing well unit, the method further comprising, after the injection of the injectant (9) is completed: and sealing the injection well (3), and sequentially connecting and extracting the injection well (3) and the extraction mechanism.
24. The method according to claim 22, wherein the injection well (3) and extraction well (2) are different said fracturing well mechanisms, the method further comprising: and injecting the injection object (9) into the injection well (3), and sequentially connecting and extracting an extraction mechanism with the extraction well (2).
25. Method according to claim 23 or 24, characterized in that the injectate (9) is injected into the injection well (3) by means of an injection unit (1).
26. The method according to claim 1 or 2, characterized in that the time for a single multi-phase extraction is 20-30 hours.
27. The method according to claim 1 or 2, characterized in that the total number of multi-phase extractions is 5-50.
28. The method of claim 26, wherein the total number of multi-phase extractions is between 5 and 10.
29. A method according to claim 1 or 2, characterized in that the total number of multiphase extractions is controlled such that the content of contaminating organic matter in the soil area (5) after the multiphase extraction is 2-100mg/Kg.
30. The method according to claim 1 or 2, characterized in that the method further comprises: the extract (10) is subjected to a post-treatment.
31. A method according to claim 30, characterized in that the extract (10) is separated to obtain organic gases, sediment and waste water, and the organic gases are subjected to a harmless treatment.
32. The method of claim 31, wherein the post-processing comprises: and (3) carrying out water washing and cooling on the extract (10), carrying out three-phase separation in a three-phase separator (7) to obtain organic gas, sediment and wastewater, and then collecting the organic gas into an exhaust gas treatment device (8) for harmless treatment.
33. The method of claim 31 or 32, wherein the innocuous treatment is selected from at least one of absorption, adsorption, water washing, alkaline washing, membrane separation, catalytic oxidation, regenerative combustion, direct combustion, plasma technology treatment, chemical oxidation, and microbiological treatment.
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