CN114989804A - Method for determining using amount of oxidizing liquid based on fracturing modification effect of shale gas layer - Google Patents
Method for determining using amount of oxidizing liquid based on fracturing modification effect of shale gas layer Download PDFInfo
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- 230000001590 oxidative effect Effects 0.000 title claims abstract description 68
- 239000007788 liquid Substances 0.000 title claims abstract description 49
- 230000000694 effects Effects 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000004048 modification Effects 0.000 title claims abstract description 20
- 238000012986 modification Methods 0.000 title claims abstract description 20
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 claims abstract description 63
- 239000011028 pyrite Substances 0.000 claims abstract description 62
- 229910052683 pyrite Inorganic materials 0.000 claims abstract description 62
- 229910000514 dolomite Inorganic materials 0.000 claims abstract description 60
- 239000010459 dolomite Substances 0.000 claims abstract description 60
- 230000003647 oxidation Effects 0.000 claims abstract description 60
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 60
- 229910021532 Calcite Inorganic materials 0.000 claims abstract description 59
- QBWCMBCROVPCKQ-UHFFFAOYSA-N chlorous acid Chemical compound OCl=O QBWCMBCROVPCKQ-UHFFFAOYSA-N 0.000 claims abstract description 47
- 229910001919 chlorite Inorganic materials 0.000 claims abstract description 46
- 229910052619 chlorite group Inorganic materials 0.000 claims abstract description 46
- 230000009466 transformation Effects 0.000 claims abstract description 22
- 230000003628 erosive effect Effects 0.000 claims abstract description 20
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 15
- 239000011707 mineral Substances 0.000 claims abstract description 15
- 238000002474 experimental method Methods 0.000 claims abstract description 5
- 230000007246 mechanism Effects 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 56
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 55
- 230000009471 action Effects 0.000 claims description 28
- 239000000126 substance Substances 0.000 claims description 28
- 235000013351 cheese Nutrition 0.000 claims description 19
- RVKQPVNRSGDRKC-UHFFFAOYSA-N OCl=O.OCl=O Chemical compound OCl=O.OCl=O RVKQPVNRSGDRKC-UHFFFAOYSA-N 0.000 claims description 16
- 239000012530 fluid Substances 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 9
- -1 polypropylene Polymers 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 230000007797 corrosion Effects 0.000 claims description 8
- 238000005260 corrosion Methods 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 239000006228 supernatant Substances 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- 239000011148 porous material Substances 0.000 claims description 4
- 239000004743 Polypropylene Substances 0.000 claims description 3
- 238000004458 analytical method Methods 0.000 claims description 3
- 239000003638 chemical reducing agent Substances 0.000 claims description 3
- 239000004927 clay Substances 0.000 claims description 3
- 239000008367 deionised water Substances 0.000 claims description 3
- 229910021641 deionized water Inorganic materials 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 239000012982 microporous membrane Substances 0.000 claims description 3
- 229920001155 polypropylene Polymers 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- 238000012216 screening Methods 0.000 claims description 3
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- 239000003381 stabilizer Substances 0.000 claims description 3
- 239000004575 stone Substances 0.000 claims description 3
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- 230000000996 additive effect Effects 0.000 claims description 2
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- 239000000243 solution Substances 0.000 description 9
- 230000001965 increasing effect Effects 0.000 description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 230000035699 permeability Effects 0.000 description 4
- 239000002253 acid Substances 0.000 description 2
- 229910001748 carbonate mineral Inorganic materials 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
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Abstract
The invention relates to an oxidizing liquid dosage determination method based on a shale gas layer fracturing modification effect, which comprises the following steps: the method comprises the steps of calculating the volume of an induced crack according to the volume ratio of a main crack to the induced crack in hydraulic fracturing, setting the oxidation transformation effect of a shale gas layer, calculating the volume of a secondary crack in each section of the oxidation transformation of the shale gas layer, obtaining the volume contribution rate of calcite, pyrite, dolomite, chlorite and kerogen in oxidation and erosion shale according to an indoor experiment, calculating the quantity of five mineral components, and calculating the consumption of an oxidizing liquid according to the chemical reaction equation of the pyrite, the calcite, the dolomite and the oxidizing liquid and the chemical reaction mechanism of the kerogen, the chlorite and the oxidizing liquid and the stoichiometric number ratio. The method disclosed by the invention is combined with the oxidative modification to expand the fracturing effect, the input-output ratio is calculated, the economic benefit of the shale gas well is effectively improved, the amount of the solid phase reduced by the oxidative modification shale gas layer is specifically calculated, the effect of the oxidative modification shale gas layer is effectively evaluated, the calculation is rapid, and the accuracy is high.
Description
Technical Field
The invention relates to the technical field of yield increasing transformation of petroleum and natural gas, and relates to a method for determining the using amount of an oxidizing liquid based on a fracturing transformation effect of a shale gas layer.
Background
Shale gas is unconventional natural gas, the resource quantity is huge, the exploitation prospect is wide, but a shale reservoir is compact, the permeability is low, the permeability of a base block is mainly from NaDaxi to MiDaxi, the heterogeneity is strong, the seepage resistance of the shale gas is huge, so that the shale gas transmission capability is extremely low, the existing horizontal well staged hydraulic fracturing technology for exploiting shale gas has serious problems, the shale gas layer recovery ratio is low, the gas well yield is decreased rapidly, the cost is high, and the economic benefit is low, so that an effective yield-increasing transformation technology is urgently needed for exploitation of shale gas.
In order to solve the problems, Chinese patent CN 105484717B proposes a method for improving the permeability of an organic-rich shale matrix, which mainly comprises adding an oxidizing solution into an injection liquid of a shale gas layer to oxidize and corrode organic matters and pyrite in a shale reservoir and to dissolve carbonate minerals in an acid manner to form corrosion pores, so that the permeability of the shale matrix is improved, and the yield-increasing efficiency is cooperatively exerted with hydraulic fracturing. However, the amount of the oxidizing solution is not specified in the patent, which makes it difficult to actually realize the engineering application.
Disclosure of Invention
The purpose of the invention is: on the basis of the existing hydraulic fracturing, an oxidizing liquid is added into a fracturing fluid pad fluid to oxidize and erode kerogen, pyrite and chlorite in a shale reservoir, acid is generated to further dissolve carbonate minerals such as calcite and dolomite to generate eroded cracks, the consumption of the oxidizing liquid required by each section of staged fracturing of the horizontal well is calculated on the basis of setting the fracturing effect of the shale gas reservoir, and the fracturing fluid pad fluid is pumped in a sequential slug type of slickwater, oxidizing liquid and slickwater in practical engineering application, so that the yield-increasing transformation effect with rapidness, low cost and no damage is realized.
In order to achieve the above object, the object of the present invention is achieved by the following technical measures:
a method for determining the usage amount of an oxidizing liquid based on the fracturing modification effect of a shale gas layer comprises the following steps:
(1) acquiring the total volume of cracks generated by a shale gas layer under the hydraulic fracturing transformation action according to the adjacent well data and the geological condition numerical simulation result;
(2) calculating the volume of the induced fracture according to the volume ratio between the main fracture and the induced fracture in the hydraulic fracturing;
(3) setting the oxidation transformation effect of the shale gas layer, and calculating the volume of a secondary crack generated by oxidation transformation of each section of the shale gas layer by combining the induced crack volume, namely the volume of the shale gas layer consumed by the action of each section of the oxidation liquid;
(4) the volume contribution rates of calcite, pyrite, dolomite, chlorite and kerogen in the shale under the action of the oxidizing liquid are obtained through experiments, and the volume consumed by the five mineral components is calculated by combining the total volume of the shale gas layer consumed by the action of the oxidizing liquid, namely the erosion volume required to be provided by the five mineral components respectively to achieve the set oxidation transformation effect, and then the volume is converted into the amount of substances of the five mineral components;
(5) according to the chemical reaction equation of the action of the pyrite, the calcite, the dolomite and the oxidizing liquid and the chemical reaction mechanism of the action of the kerogen, the chlorite and the oxidizing liquid, the amount of substances of the oxidizing liquid required to be consumed by the five mineral components is calculated by using stoichiometric ratio, and further the volume of the oxidizing liquid required to be consumed is obtained.
The total volume of the cracks generated by the shale gas layer under the hydraulic fracturing transformation effect is numerically simulated mainly through adjacent well data and geological conditions, the single well crack volume is predicted, and a scheme is formulated.
The volume contribution rate of calcite, pyrite, dolomite, chlorite and kerogen in the shale gas layer under the action of the oxidizing solution is obtained by an indoor experiment, and the method comprises the following steps:
(1) taking a shale sample on site, drying, crushing and screening, taking a shale powder sample, and weighing the masses of calcite, pyrite, dolomite, chlorite and kerogen respectively;
(2) fully mixing a shale powder sample and an excessive hydrogen peroxide solution in a polypropylene centrifugal tube;
(3) shaking the centrifugal tube in a constant-temperature water bath at the reservoir temperature for a certain time;
(4) centrifuging the test tube after reaction, separating supernatant and residues, and filtering the supernatant through a microporous membrane for water chemical analysis;
(5) washing the residue with deionized water, centrifuging repeatedly to remove dissolved salts, drying at reservoir temperature, collecting and weighing to obtain dissolved components with mass reduction of calcite, pyrite, kerogen, dolomite and chlorite respectively m 1 、m 2 、m 3 、m 4 、m 5 。
(6) The volume contributions of calcite, pyrite, kerogen, dolomite and chlorite were calculated according to the following formula:
in the formula, V 4 Pore volume, cm, of corrosion generated for oxidative modification of shale in laboratory experiments 3 (ii) a a is the volume contribution rate,%, of the reconstructed calcite by oxidation; b is the volume contribution rate of the oxidized and reformed pyrite percent; c is the volume contribution rate of kerogen oxidized and reformed in percent; d is the volume contribution rate,%, of the oxidized and reformed dolomite; e is the volume contribution rate of the oxidized and reformed chlorite,%; rho Calcite Is calcite density; rho Pyrite Is the pyrite density; rho Root of cheese Is the kerogen density; rho Dolomite Is the dolomite density; rho Chlorite (chlorite) Is the chlorite density.
The chemical reaction equation of the action of the pyrite, the calcite and the dolomite with the oxidizing liquid is as follows:
CaCO 3 +2H + →Ca 2+ +CO 2 +H 2 O
CaMg(CO 3 ) 2 +4H + →Ca 2+ +Mg 2+ +2CO 2 +2H 2 O
the chemical reaction mechanism of the kerogen and the oxidizing liquid mainly takes the breakage of chemical bonds of C-O and C ═ O, and the chemical reaction mechanism of the chlorite and the oxidizing liquid takes Fe 2+ Is oxidized into Fe 3+ Mainly, Fe in chlorite 2+ In the form of FeO.
As a preferred technical scheme, the oxidizing agent in the oxidizing solution is a main reaction consumable and is hydrogen peroxide; and is matched with a resistance reducing agent, a discharge aiding agent and a clay stabilizer; in the hydraulic fracturing process, the oxidizing liquid is placed in the pad fluid.
As a preferred technical scheme, the volume of the hydraulic fracture inducing crack and the volume of the shale gas layer consumed by each section of oxidizing fluid are calculated according to the following formula:
in the formula, V 1 Induced fracture volume for hydraulic fracturing, m 3 ；V c Total volume of cracks m generated in shale gas layer under hydraulic fracturing reconstruction effect 3 ；V 2 Consuming the total volume of shale gas layer, m, for the action of oxidizing fluid 3 (ii) a x is the set shale gas layer oxidation transformation effect; v 3 The volume of a shale gas layer is consumed for the action of each section of oxidizing liquid in the staged fracturing of the horizontal well, and m is 3 (ii) a y is the number of staged fracturing sections of the horizontal well; z is the volume fraction between the main and induced fractures of the hydraulic fracture.
As a preferred technical scheme, the erosion volume and the amount of the corresponding substances which are respectively required to be provided by the five mineral components to achieve the set oxidative modification effect are calculated according to the following formula:
V calcite ＝aV 3 
V Pyrite ＝bV 3 
V Root of cheese ＝cV 3 
V Dolomite ＝dV 3 
V Chlorite (chlorite) ＝eV 3 
In the formula, V Calcite Erosion volume provided by calcite under Oxidation, m 3 ；n Calcite The amount of calcite consumed by oxidation, mol; m Calcite Is the molar mass of calcite; v Pyrite Corrosion volume, m, provided for pyrite under oxidation 3 ；n Pyrite The amount of the consumed substances of the pyrite under the oxidation action, mol; m Pyrite Is the molar mass of pyrite; v Root of cheese Erosion volume, m, provided for kerogen under oxidation 3 ；n Root of cheese The amount of material consumed by kerogen under oxidation, mol; m Root of cheese Is the molar mass of kerogen; v Dolomite Erosion volume, m, provided for dolomite under oxidation 3 ；n Dolomite The amount of the consumed substance of dolomite under the oxidation action, mol; m is a group of Dolomite Is the molar mass of dolomite; v Chlorite (chlorite) Erosion volume, m, provided for chlorite under oxidation 3 ；n Chlorite (chlorite) The amount of material consumed by chlorite under oxidation, mol; m Chlorite (chlorite) Is the molar mass of chlorite.
As a preferred technical solution, the amount and volume of the substances of the oxidizing liquid to be consumed by the five minerals are calculated according to the following formula:
n(H + ) 1 ＝361.1n chlorite stone +n Pyrite +n Root of cheese
n(H + ) 2 ＝2n Calcite +4n Dolomite
In the formula, n (H) + ) 1 For the reaction of hydrogen peroxide with chlorite, pyrite and kerogen to produce H + Amount of substance(s), mol; n (H) + ) 2 H is required for the consumption of calcite and dolomite + Amount of substance(s), mol;
the amount of hydrogen peroxide consuming material, mol, required to produce the corresponding oxidation modification volume;
is the density of hydrogen peroxide;
is the molar mass of hydrogen peroxide.
The beneficial effects are that:
(1) the amount of the oxidizing liquid is calculated by theoretical derivation, the method is simple, the calculation is rapid, and the accuracy is high;
(2) the fracturing effect is enlarged by combining with the oxidation transformation, the using amount of the oxidation liquid is adjusted at any time according to the field condition, the input-output ratio is calculated, and the economic benefit of the shale gas well is effectively improved;
(3) the amount of solid phases such as calcite, dolomite, chlorite, pyrite and the like can be effectively reduced by oxidizing the reformed shale gas layer, and the method can realize specific calculation and effectively evaluate the effect of oxidizing the reformed shale gas layer.
Drawings
FIG. 1 is a flow chart of a method for determining the amount of an oxidizing fluid based on the fracturing reformation effect of a shale gas layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments; it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the embodiment of the invention, the use amount of the oxidizing liquid based on the fracturing modification effect of the shale gas layer is calculated by taking a deep shale gas well of the Longmaxi group in Sichuan as an example.
(1) Volume of secondary crack generated by each stage of oxidation transformation
In the formula, V 1 Induced fracture volume for hydraulic fracturing, m 3 ；V c Total volume of cracks m generated in shale gas layer under hydraulic fracturing reconstruction effect 3 ；V 2 Consuming the total volume of shale gas layer, m, for the action of oxidizing fluid 3 (ii) a x is the set shale gas layer oxidation transformation effect; v 3 The volume of a shale gas layer is consumed for the action of each section of oxidizing liquid in the staged fracturing of the horizontal well, and m is 3 (ii) a y is the number of staged fracturing sections of the horizontal well; z is the volume fraction between the main and induced fractures of the hydraulic fracture.
The total volume of the cracks generated by the shale gas layer under the hydraulic fracturing transformation effect is 454m 3 Hydraulic fracturingInduced fracture volume is 227m 3 Setting the oxidation transformation effect of a shale gas layer to be 30%, setting the number of staged fracturing sections of a horizontal well to be 9, and setting the volume ratio of a main hydraulic fracturing crack to an induced crack to be 1: 1; each section of oxidation transformation generates a secondary crack with the volume of 25.22m 3 。
(2) Volume contribution rate of five minerals under action of oxidizing liquid
1) Taking a shale sample on site, drying, crushing and screening until the grain size is less than 75 mu m, and taking 1g of shale powder sample, and respectively weighing the masses of calcite, pyrite, dolomite, chlorite and kerogen;
2) fully mixing 1g of shale powder sample with 20mL of hydrogen peroxide solution in a 50mL polypropylene centrifuge tube;
3) the concentration of hydrogen peroxide is 1mol/L, and the centrifuge tube is shaken in a constant temperature water bath at 65 ℃ for 48 hours;
4) centrifuging the tube at 4000rpm for 2min after reaction, separating supernatant and residue, and filtering the supernatant through a microporous membrane for water chemical analysis;
5) washing the residue with deionized water, centrifuging at 4000rpm for 2min, repeating for 3 times to remove dissolved salts, drying at 65 deg.C for 36 hr, collecting and weighing to obtain dissolved components with mass reduction of calcite, pyrite, kerogen, dolomite and chlorite respectively of m 1 、m 2 、m 3 、m 4 、m 5 。
6) The volume contributions of calcite, pyrite, kerogen, dolomite and chlorite were calculated according to the following formula:
in the formula, V 4 Pore volume etched in cm generated for oxidative modification of 1g of shale 3 (ii) a a is the volume contribution rate,%, of the reconstructed calcite by oxidation; b is oxygenThe volume contribution rate of the chemically transformed pyrite is percent; c is the volume contribution rate of kerogen oxidized and reformed in percent; d is the volume contribution rate,%, of the oxidized and reformed dolomite; e is the volume contribution rate of the oxidized and reformed chlorite; rho Calcite The density of the calcite is 2.7g/cm 3 ；ρ Pyrite Taking 4.9g/cm as pyrite density 3 ；ρ Root of cheese Taking 1.5g/cm as kerogen density 3 ；ρ Dolomite Taking the density of dolomite as 2.85g/cm 3 ；ρ Chlorite (chlorite) The chlorite density is 3.6g/cm 3 。
The volume contribution rate of the oxidized and modified calcite is 62.84%, the volume contribution rate of the oxidized and modified pyrite is 13.44%, the volume contribution rate of the oxidized and modified kerogen is 12.87%, the volume contribution rate of the oxidized and modified dolomite is 5.18%, and the volume contribution rate of the oxidized and modified chlorite is 5.67%.
(3) The amounts of the five mineral components to be provided separately
V Calcite ＝aV 3 
V Pyrite ＝bV 3 
V Root of cheese ＝cV 3 
V Dolomite ＝dV 3 
V Chlorite stone ＝eV 3 
In the formula, V Calcite Eroding body for calcite under oxidationProduct of m 3 ；n Calcite The amount of calcite consumed by oxidation, mol; m Calcite Taking 100g/mol as the molar mass of calcite; v Pyrite Corrosion volume, m, provided for pyrite under oxidation 3 ；n Pyrite The amount of the consumed substances of the pyrite under the oxidation action, mol; m Pyrite Taking 120g/mol as the molar mass of the pyrite; v Root of cheese Erosion volume, m, provided for kerogen under oxidation 3 ；n Root of cheese The amount of material consumed by kerogen under oxidation, mol; m Root of cheese Taking 30g/mol as the molar mass of kerogen; v Dolomite Erosion volume, m, provided for dolomite under oxidation 3 ；n Dolomite The amount of the consumed substance of dolomite under the oxidation action, mol; m Dolomite Taking 184.4g/mol as the molar mass of dolomite; v Chlorite (chlorite) Erosion volume, m, provided for chlorite under oxidation 3 ；n Chlorite (chlorite) The amount of material consumed by chlorite under oxidation, mol; m is a group of Chlorite (chlorite) 72g/mol is taken as the molar mass of chlorite.
The erosion volume provided by calcite under oxidation is 15.848m 3 (ii) a The corrosion volume provided by pyrite under oxidation is 3.39m 3 (ii) a The erosion volume provided by kerogen under oxidation is 3.246m 3 (ii) a The erosion volume provided by dolomite under oxidation is 1.3064m 3 (ii) a The erosion volume provided by chlorite under oxidation is 1.43m 3 。
(4) Amount of oxidizing liquid
n(H + ) 1 ＝361.1n Chlorite (chlorite) +n Pyrite +n Root of cheese
n(H + ) 2 ＝2n Calcite +4n Dolomite
In the formula, n (H) + ) 1 For the reaction of hydrogen peroxide with chlorite, pyrite and kerogen to produce H + Amount of substance(s), mol; n (H) + ) 2 H is required for the consumption of calcite and dolomite + Amount of substance(s), mol;
the amount of hydrogen peroxide consuming material, mol, required to produce the corresponding oxidation modification volume;
the density of hydrogen peroxide was 1.463g/cm 3 ；
34g/mol are taken as the molar mass of hydrogen peroxide.
Reaction of hydrogen peroxide with chlorite, pyrite, and kerogen to produce H + The amount of (A) is 7787662.5mol, H is required for the consumption of calcite and dolomite + The amount of substance(s) of (2) is 281946.6 mol; it can be derived that: generally, hydrogen peroxide reacts with chlorite, pyrite, and kerogen to produce H + The amount of the substance(s) of (a) is much greater than the amount of the substance(s) requiring H + for the consumption of calcite and dolomite, and therefore the situation where the amount of the H + producing substance(s) is insufficient is not considered; the volume of hydrogen peroxide required for consuming pyrite was 7.237933m 3 The volume of hydrogen peroxide required for kerogen consumption was 2.2632m 3 The volume of hydrogen peroxide required for chlorite consumption was 0.24927m 3 。
The consumption of each section of pad fluid in the shale gas well subsection hydraulic fracturing is 100m 3 And 9.75m is added according to the calculation result 3 The hydrogen peroxide is prepared into an oxidizing solution consisting of 9.75 percent of hydrogen peroxide, 0.05 percent of resistance reducing agent, 0.05 percent of cleanup additive and 1 percent of clay stabilizer in field application, and the oxidizing solution-slickwater are pumped in sequence, so that the effect of expanding the fracturing is 30 percent.
In addition, in practical application, the price of 30 percent hydrogen peroxide in each part is about 700 yuan, and the calculation is combined to calculate that each stage of fracturing needs 30 percent hydrogen peroxide of 32.5m 3 The cost of the oxidation liquid added to each stage of fracturing is calculated to be about 2.5 ten thousand yuan, and the cost of a single well is increased by 22.5 ten thousand yuan.
The average daily output of shale gas wells in the region is 10000m 3 The yield increasing effect is about 25 percent under the condition of expanding the fracturing effect by 30 percent according to the adjacent well data and the numerical simulation result of the geological condition, and the daily yield increasing effect is 2500m 3 Combining with shale gas subsidy standard of 0.2 yuan/m 3 The income is increased by 500 yuan per day, and the root is recovered within 450 days.
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (6)
1. A method for determining the usage amount of an oxidizing liquid based on the fracturing modification effect of a shale gas layer is characterized by comprising the following steps:
(1) acquiring the total volume of cracks generated by a shale gas layer under the hydraulic fracturing transformation action according to the adjacent well data and the geological condition numerical simulation result;
(2) calculating the volume of the induced fracture according to the volume ratio between the main fracture and the induced fracture in the hydraulic fracturing;
(3) setting the oxidation transformation effect of the shale gas layer, and calculating the volume of a secondary crack generated by oxidation transformation of each section of the shale gas layer by combining the induced crack volume, namely the volume of the shale gas layer consumed by the action of each section of the oxidation liquid;
(4) volume contribution rates of calcite, pyrite, dolomite, chlorite and kerogen in shale under the action of the oxidizing liquid are obtained through experiments, and the volume consumed by the five mineral components is calculated by combining the total volume of the shale gas layer consumed by the action of the oxidizing liquid, namely, the erosion volumes required to be provided by the five mineral components respectively and achieving the set oxidation modification effect, so that the volumes are converted into the quantities of substances of the five mineral components;
(5) according to the chemical reaction equation of the action of the pyrite, the calcite, the dolomite and the oxidizing liquid and the chemical reaction mechanism of the action of the kerogen, the chlorite and the oxidizing liquid, the amount of substances of the oxidizing liquid required to be consumed by the five mineral components is calculated by using stoichiometric ratio, and further the volume of the oxidizing liquid required to be consumed is obtained.
2. The method for determining the amount of the oxidizing liquid based on the fracturing reformation effect of the shale gas layer as claimed in claim 1, wherein the method comprises the following steps: the oxidant in the oxidizing liquid is a main reaction consumable and is hydrogen peroxide; and adding resistance reducing agent, cleanup additive and clay stabilizer, and placing the oxidizing liquid in the pad fluid during the hydraulic fracturing process.
3. The method for determining the amount of the oxidizing liquid based on the fracturing reformation effect of the shale gas layer as claimed in claim 1, wherein the method comprises the following steps: calculating the volume of the hydraulic fracturing induced fracture and the volume of the shale gas layer consumed by each section of oxidizing fluid according to the following formula:
in the formula, V 1 Induced fracture volume for hydraulic fracturing, m 3 ；V c Total volume of cracks m generated in shale gas layer under hydraulic fracturing reconstruction effect 3 ；V 2 Consuming the total volume of shale gas layer, m, for the action of oxidizing fluid 3 (ii) a x is the set shale gas layer oxidation transformation effect; v 3 The volume of a shale gas layer is consumed for the action of each section of oxidizing liquid in the staged fracturing of the horizontal well, and m is 3 (ii) a y is a horizontal wellThe number of staged fracturing stages; z is the volume fraction between the main and induced fractures of the hydraulic fracture.
4. The method for determining the amount of the oxidizing liquid based on the fracturing reformation effect of the shale gas layer as claimed in claim 1, wherein the method comprises the following steps: the volume contribution rate of calcite, pyrite, dolomite, chlorite and kerogen in the shale gas layer under the action of the oxidizing solution is obtained by an indoor experiment, and the method comprises the following steps:
(1) taking a shale sample on site, drying, crushing and screening, taking a shale powder sample, and weighing the masses of calcite, pyrite, dolomite, chlorite and kerogen respectively;
(2) fully mixing a shale powder sample and an excessive hydrogen peroxide solution in a polypropylene centrifugal tube;
(3) shaking the centrifugal tube in a constant-temperature water bath at the reservoir temperature for a certain time;
(4) centrifuging the test tube after reaction, separating supernatant and residues, and filtering the supernatant through a microporous membrane for water chemical analysis;
(5) washing the residue with deionized water, centrifuging repeatedly to remove dissolved salts, drying at reservoir temperature, collecting and weighing to obtain dissolved components with mass reduction of calcite, pyrite, kerogen, dolomite and chlorite respectively m 1 、m 2 、m 3 、m 4 、m 5 。
(6) The volume contributions of calcite, pyrite, kerogen, dolomite and chlorite were calculated according to the following formula:
in the formula, V 4 Pore volume, cm, of corrosion generated for oxidative modification of shale in laboratory experiments 3 (ii) a a is the volume contribution rate,%, of the calcite subjected to oxidative modification; b is the volume contribution rate of the oxidized and reformed pyrite percent; c is the volume contribution rate of kerogen oxidized and reformed in percent; d is the volume contribution rate,%, of the oxidized and reformed dolomite; e is the volume contribution rate of the oxidized and reformed chlorite,%; ρ is a unit of a gradient Calcite Is calcite density; rho Pyrite Is the pyrite density; rho Root of cheese Is the kerogen density; rho Dolomite Is the dolomite density; rho Chlorite stone Is the chlorite density.
5. The method for determining the amount of the oxidizing liquid based on the fracturing reformation effect of the shale gas layer as claimed in claim 1, wherein the method comprises the following steps: calculating the erosion volume and the corresponding substance amount which are respectively required to be provided by the five mineral components to achieve the set oxidation modification effect according to the following formula:
V calcite ＝aV 3 
V Pyrite ＝bV 3 
V Root of cheese ＝cV 3 
V Dolomite ＝dV 3 
V Chlorite (chlorite) ＝eV 3 
In the formula, V Calcite Erosion volume, m, provided for calcite under oxidation 3 ；n Calcite The amount of calcite consumed by oxidation, mol; m is a group of Calcite Is the molar mass of calcite; v Pyrite Corrosion volume, m, provided for pyrite under oxidation 3 ；n Pyrite The amount of the consumed substances of the pyrite under the oxidation action, mol; m Pyrite Is the molar mass of pyrite; v Root of cheese Eroding volume, m, provided for kerogen under oxidation 3 ；n Root of cheese The amount of material consumed by kerogen under oxidation, mol; m Root of cheese Is the molar mass of kerogen; v Dolomite Corrosion volume, m, provided for dolomite under oxidation 3 ；n Dolomite The amount of the consumed substance of dolomite under the oxidation action, mol; m Dolomite Is the molar mass of dolomite; v Chlorite (chlorite) Erosion volume, m, provided for chlorite under oxidation 3 ；n Chlorite (chlorite) The amount of material consumed by chlorite under oxidation, mol; m Chlorite (chlorite) Is the molar mass of chlorite.
6. The method for determining the amount of the oxidizing liquid based on the fracturing reformation effect of the shale gas layer as claimed in claim 1, wherein the method comprises the following steps: the amount and volume of the substances of the oxidizing liquid required to be consumed by the five minerals are calculated according to the following formula:
n(H + ) 1 ＝361.1n chlorite (chlorite) +n Pyrite +n Root of cheese
n(H + ) 2 ＝2n Calcite +4n Dolomite
n H2O2 ＝7.5n Pyrite +0.5n Chlorite (chlorite) +2n Root of cheese
In the formula, n (H) + ) 1 For the reaction of hydrogen peroxide with chlorite, pyrite and kerogen to produce H + Amount of substance(s), mol; n (H) + ) 2 To consumeCalcite and dolomite require H + Amount of substance(s), mol; n is H2O2 The amount of hydrogen peroxide consuming material, mol, required to produce the corresponding oxidation modification volume; rho H2O2 Is the density of hydrogen peroxide; m H2O2 Is the molar mass of hydrogen peroxide.
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