CN113863913B - Shale gas layer oxidation burst transformation method - Google Patents
Shale gas layer oxidation burst transformation method Download PDFInfo
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- 230000003647 oxidation Effects 0.000 title claims abstract description 53
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 53
- 238000011426 transformation method Methods 0.000 title claims abstract description 6
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 87
- 239000007789 gas Substances 0.000 claims abstract description 70
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 47
- 239000007788 liquid Substances 0.000 claims abstract description 36
- 238000004880 explosion Methods 0.000 claims abstract description 26
- 238000003421 catalytic decomposition reaction Methods 0.000 claims abstract description 23
- 230000001590 oxidative effect Effects 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 15
- 230000008569 process Effects 0.000 claims abstract description 8
- 230000009172 bursting Effects 0.000 claims abstract description 7
- 230000009466 transformation Effects 0.000 claims abstract description 6
- 238000002347 injection Methods 0.000 claims description 31
- 239000007924 injection Substances 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 239000000243 solution Substances 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000003292 glue Substances 0.000 claims description 10
- 230000015572 biosynthetic process Effects 0.000 claims description 9
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 238000002715 modification method Methods 0.000 claims description 9
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims description 8
- 230000006835 compression Effects 0.000 claims description 7
- 238000007906 compression Methods 0.000 claims description 7
- 230000003197 catalytic effect Effects 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 claims description 5
- 239000011435 rock Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000011259 mixed solution Substances 0.000 claims description 2
- 238000012856 packing Methods 0.000 claims description 2
- 239000007943 implant Substances 0.000 claims 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 9
- 239000001301 oxygen Substances 0.000 abstract description 9
- 229910052760 oxygen Inorganic materials 0.000 abstract description 9
- 239000011148 porous material Substances 0.000 abstract description 7
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- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
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- 229930195733 hydrocarbon Natural products 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/27—Methods for stimulating production by forming crevices or fractures by use of eroding chemicals, e.g. acids
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/263—Methods for stimulating production by forming crevices or fractures using explosives
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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- Engineering & Computer Science (AREA)
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- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical & Material Sciences (AREA)
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Abstract
The invention discloses a shale gas layer oxidation burst transformation method, which comprises the following steps: performing hydraulic fracturing transformation on a shale gas well to be fractured; in the hydraulic fracturing process, slickwater A, an oxidizing solution, gel-containing liquid slickwater, a catalytic decomposition solution and slickwater B are sequentially pumped in a slug type. According to the invention, methane gas released by fracturing of slickwater A is mixed with oxygen generated by decomposing hydrogen peroxide in an oxidizing solution to induce oxidation bursting, and a method for calculating the dosage of the fracturing solution and the wave and radius of the oxidation bursting is provided by integrating physical properties and chemical thermodynamic properties of shale, so that safe, efficient and harmless hydraulic fracture-explosion fracture-corrosion pore fracture multi-scale yield increase transformation is realized.
Description
Technical Field
The invention relates to a new yield-increasing transformation method in the technical field of oil and natural gas exploitation, in particular to a shale gas layer oxidation bursting transformation method.
Background
The shale reservoir stratum has the characteristics of compact base block, strong heterogeneity and the like, the pore throat of the base block mainly takes nanoscale organic matter pores and clay mineral inter-granular pores, the permeability of the base block is mainly between Nadarcy and micro Dadarcy, the shale gas seepage resistance is large, and adsorption/free gas coexists. Shale gas output needs to be subjected to a desorption-diffusion-seepage series process, however, the desorption-diffusion process of adsorbed gas in nano pores is slow, and free gas diffusion-seepage resistance is large, so that shale gas transmission capacity is extremely low, and an effective yield increase transformation technology is needed.
At present, horizontal well staged hydraulic fracturing is a main yield increasing and modifying means for shale oil and gas reservoirs, a shale base block is broken through hydraulic fracturing, and natural cracks are opened at the same time, so that a complex artificial crack network is formed in a gas reservoir, the seepage distance of gas from matrix pores to cracks is shortened, the drainage area is increased, and economic development of the shale gas reservoir is realized. However, shale reservoir recovery is generally low, and shale reservoir recovery is far lower than that of a conventional reservoir, and is only about 10% -16%. The recovery ratio of shale gas layers in North America regions is generally 5% -20%, and particularly the recovery ratio in Barnett regions is only about 10%. From a long-term development perspective, enhanced recovery is an inevitable option for shale oil and gas development.
Secondly, although the fracture network formed by the primary hydraulic fracturing is beneficial to improving the seepage capability of the shale gas layer, the difficult problem of low gas desorption-diffusion transmission capability in the pores of the matrix at the far ends of the fractures still cannot be solved, so that the gas supply capability of the shale matrix is far lower than the gas transmission capability in the fractures, the gas well yield at the initial stage of exploitation is decreased exponentially, the commercial exploitation period is shortened, the recovery ratio is reduced, and the development cost is increased.
Analysis suggests that improving the efficiency of methane gas production in shale-based blocks is primarily an increase in the diffusion rates of adsorbed and free gases. Because the shale matrix is compact, the microcracks become the main gas seepage channels, so that more microcracks are generated to shorten the diffusion path of methane gas in nanopores, and the method is a main idea for increasing the yield of the shale gas layer by hydraulic fracturing. The existing research shows that compared with hydraulic support fractures, the contact area between a non-support fracture formed by stress disturbance in the fracturing process and a shale foundation block is larger, and the seepage area in a wider range is controlled, so that the method has important significance for delaying the rapid decrement of the yield of the shale gas well. Therefore, on the basis of hydraulic fracturing, more unsupported cracks or secondary microcracks are obtained, and the method is one of important breakthrough openings for enhancing the fracturing modification effect and improving the shale gas recovery efficiency.
Disclosure of Invention
The invention aims to realize secondary reconstruction after shale gas lamination by generating local bursting at a fracturing well section based on the existing hydraulic fracturing technology so as to improve the fracture forming efficiency and the fracture density of the existing fracturing reconstruction method and supplement and enhance the existing fracturing reconstruction effect. In the invention, slickwater A-oxidizing liquid-gel-containing liquid slickwater-catalytic decomposition liquid-slickwater B is plug-injected into the middle section of the well-entering fracturing liquid, and methane gas released by fracturing of slickwater A is mixed with oxygen generated by decomposing hydrogen peroxide in the oxidizing liquid to induce oxidation burst, thereby realizing the effect of rapid, low-cost and harmless yield increase transformation.
The specific technical scheme of the invention is as follows:
a shale gas layer oxidation burst modification method comprises the following steps:
performing hydraulic fracturing transformation on the shale gas well to be fractured;
in the hydraulic fracturing process, slickwater A-oxidizing liquid-gel-containing liquid slickwater-catalytic decomposition liquid-slickwater B are sequentially pumped in a segmented plug type fluid state.
The slickwater A is mainly used for hydraulic fracturing and crack making, and part of methane gas is released;
the oxidizing liquid is a mixed liquid of hydrogen peroxide and dilute hydrochloric acid, and the dilute hydrochloric acid is used for preventing the hydrogen peroxide from decomposing in the shaft;
the injection amount of the glue-containing liquid slickwater is larger than the effective volume of the shaft, so that hydrogen peroxide in the shaft can completely enter a fracturing crack, and a catalytic decomposition agent in the catalytic decomposition liquid and the hydrogen peroxide in the oxidizing liquid can be prevented from reacting in the shaft in advance;
the catalytic decomposition liquid uses slickwater containing catalytic decomposition agent, and the catalytic decomposition agent comprises but is not limited to sodium hydroxide and manganese dioxide;
and the slickwater B seals and separates the oxidizing liquid, so that the local burst in the shale hydraulic fracture is generated at the end far away from the shaft, and the integrity of the shaft is prevented from being damaged.
As a preferred solution, the injection amount of slickwater a is calculated according to the following formula:
in the formula, V 1 Respectively the volume of the slickwater A; alpha is the leakage coefficient, and 1.0-1.5 is taken; d is the outer diameter of the sleeve; delta is the wall thickness of the sleeve; h is the well depth; l is the depth of explosion point; h is the height of a main hydraulic fracture; w is the width of the main fracture of the hydraulic fracture.
In a preferred embodiment, the oxidizing solution is a mixed solution of hydrogen peroxide and dilute hydrochloric acid.
As a preferred solution, the hydrogen peroxide injection mass and the oxidation burst wave and radius are calculated according to the following formula:
in the formula, P o Is the original formation pressure; sigma is rock tensile strength; phi is the dense gas layer porosity; r is the oxidation explosion wave radius; r is an ideal gas constant; z o Is the pre-oxidation decrepitation gas compression factor; z m Is a gas compression factor after oxidation explosion; t is o Original formation temperature, K; m is the hydrogen peroxide injection mass; m H2O2 Is the molar mass of hydrogen peroxide; m CH4 Is the molar mass of methane; c is the specific heat capacity of methane; q is the heating value of methane when the product is gaseous water.
As a preferred technical scheme, according to a calculation formula of the hydrogen peroxide injection mass and the oxidation burst wave sum radius, the hydrogen peroxide injection mass m is given, a unitary high-order equation of the oxidation burst wave sum radius r is obtained, and the unitary high-order equation of the oxidation burst wave sum radius r is solved to obtain the oxidation burst wave sum radius r;
or, according to a calculation formula of the hydrogen peroxide injection mass and the oxidation burst wave sum radius, giving the oxidation burst wave sum radius r to obtain a unitary high-order equation of the hydrogen peroxide injection mass m, and solving the unitary high-order equation of the hydrogen peroxide injection mass m to obtain the hydrogen peroxide injection mass m.
Preferably, the injection amount of the rubber-containing liquid slickwater is larger than the effective volume of the well bore.
As a preferred technical scheme, the injection amount of the slickwater containing glue solution is calculated according to the following formula:
in the formula, V 2 Is a slippery water body containing glue liquidAccumulating; beta is a safety coefficient, and is 1.0-1.5; d is the outer diameter of the sleeve; delta is the casing wall thickness and h is the well depth.
Preferably, the catalytic decomposition solution is prepared by adding a catalytic decomposition agent to the slick water, wherein the catalytic decomposition agent includes, but is not limited to, sodium hydroxide and manganese dioxide.
As a preferable embodiment, the injection amount of the catalytic decomposition liquid is calculated according to the following formula:
in the formula, V 4 Is a catalytic decomposition liquid; rho is the density of the slick water; and m is the hydrogen peroxide injection mass.
As a preferable technical scheme, the slickwater B is used for packing the oxidizing liquid, so that local bursting in a shale hydraulic fracture is generated at the end far away from a shaft, and the integrity of the shaft is prevented from being damaged;
calculating the injection amount of the slickwater B according to the following formula:
in the formula, V 5 Is the volume of slickwater B; d is the outer diameter of the sleeve; delta is the wall thickness of the sleeve; h is the well depth; l is the depth of explosion point; h is the height of a main hydraulic fracture; w is the width of the main fracture of the hydraulic fracture.
Has the advantages that:
(1) Increasing the seam web density and complexity. Based on the artificial fractures formed by hydraulic fracturing, oxidative decrepitation further increases fracture density and depth, thereby forming a more dense network of spherical fractures.
(2) The construction operation is convenient and safe. In the hydraulic fracturing process, the fracturing fluid is injected into a reservoir layer together with the conventional fracturing fluid in a segmented mode, and the oxidation burst is generated in the hydraulic fracture far away from a shaft due to the reasonable injection amount of the fracturing fluid.
(3) Fully utilizes chemical energy and has low economic cost. The composite action of high temperature and high pressure generated by explosion of combustible gas is combined to calculate the range of oxidative burst so as to provide guidance for process implementation, and meanwhile, the hydrogen peroxide solution is widely applied to multiple links of petroleum exploration and development, is relatively low in price, and effectively controls the economic cost of fracturing yield increase.
(4) The method is established on the existing hydraulic fracturing shale gas well, additional drilling is not needed, the required energy is derived from the oxygen generated by the decomposition of the hydrocarbon gas in the reservoir and the hydrogen peroxide, the exploitation cost of the shale oil gas is reduced, and the hydraulic fracturing reformation effect is further improved. When the scale of the same hydraulic fracturing is compared, the oxidative burst is cooperated with the hydraulic fracturing modification, so that the modification volume (SRV) of the reservoir is favorably improved; for a deeper shale gas reservoir (more than 3500 m), under the condition of poor hydraulic fracturing effect, the invention provides a new idea for effective development of deep shale gas.
Drawings
In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
Fig. 1 is a schematic illustration of the inflow of a working fluid during staged hydraulic fracturing of a shale gas formation horizontal well in accordance with an embodiment of the present invention;
FIG. 2 is a schematic illustration of a fracturing fluid influx and oxygen generation process after a first stage of hydraulic fracturing in accordance with an embodiment of the present invention;
FIG. 3 is a schematic illustration of a first stage shale gas layer oxidation decrepitation modification in accordance with an embodiment of the present invention;
in the figure, a-shale gas layer; b-slickwater B; c-catalyzing the decomposition liquid; d-slick water containing glue liquid; e-oxidizing liquid; f-slickwater A; g-bridge plug; h-horizontal well; i-hydraulic fracturing the main fracture; j-oxidizing liquid and catalytic decomposing liquid; k-oxide fracture network.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as upper, lower, left, right, front, and rear … …) in the embodiments of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In order to make the objects, technical solutions and advantages of the present invention more apparent, 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.
The invention will now be further described with reference to the accompanying drawings.
As shown in figure 1, the shale gas layer horizontal well is subjected to hydraulic fracturing modification according to the invention, working fluid entering the well is injected in a slug type in sequence, slickwater A (figure 1 f) is pumped in an early stage to perform hydraulic fracturing modification (figure 2), conditions are created for sufficient contact between the subsequently injected oxidizing fluid (figure 2 e) and the catalytic decomposition fluid (figure 2 c) in the artificial fracturing, and the slickwater containing glue (figure 2 d) is used for separating the oxidizing fluid and the catalytic decomposition fluid in a well bore. The oxidizing fluid is then displaced inside the fracture by pumping slickwater B (fig. 3B) to keep the oxidative burst away from the wellbore. Considering the pumping action during the fracturing, the methane content in the artificial fractures is constant, when the oxygen amount generated by the catalytic decomposition of the hydrogen peroxide solution reaches the range required by the shale oxidation and explosion, the mixed gas of methane and oxygen detonates at high temperature and high pressure to crack the shale base block to generate a fracture network (figure 3K), thereby realizing the secondary reconstruction of the reservoir.
Considering the difference in explosion limits when methane is mixed with different gases: under normal temperature and normal pressure, the explosion limit of methane in the air is about 5-15%; whereas in pure oxygen the explosion limit of methane is about 5.0% to 61%; the molecular thermal motion is more violent under high temperature and high pressure, the explosion limit of the methane-air mixture is 2.87% -64.40% at the temperature of 20MPa and 100 ℃, and the explosion theoretical critical oxygen content can be reduced to 5.74%. The injection amount of the hydrogen peroxide can be adjusted to reach the ratio value required by methane explosion.
In the embodiment of the invention, the amount of the fracturing fluid required by the oxidation burst is calculated by taking a deep shale gas well of the Longmaxi group in the Sichuan basin as an example.
(1) Slick water A
The using amount of the slickwater A is determined according to the position of an explosion point and the shape of a hydraulic fracture and is adjusted according to a small fracturing test.
In the formula, V 1 Respectively representing the volume of slickwater A and m3; alpha is the leakage coefficient, and is 1.0-1.5; d is the outer diameter of the sleeve, m; delta is the casing wall thickness, m; h is the well depth, m; l is the detonation depth, m; h is the height of a hydraulic fracturing main crack, m; w is the width of the main fracture of hydraulic fracturing, m.
The outer diameter of the casing is 139.7mm, the wall thickness is 12.7mm, the well bore is 5100m, the depth of a first explosion point is 70m, the height of a hydraulic fracturing main crack is 20m, the width of the hydraulic fracturing main crack is 0.03m, and the dosage of slickwater A is 164m 3 。
(2) Oxidizing liquid and oxidation burst spread
The oxidizing liquid is a mixed liquid of hydrogen peroxide and dilute hydrochloric acid (the mass concentration of the hydrogen peroxide is 20%), and the oxidation explosion occurs by two steps of mixed combustion reaction of oxygen, oxygen and methane generated by the decomposition of the hydrogen peroxide. The hydrogen peroxide injection quality determines a sweep range, namely the radius of an oxidation explosion crack network, the maximum explosion pressure generated when the mixture explodes can be determined in a proportional relation between the pressing force and the thermodynamic temperature and the mole number, and the hydrogen peroxide injection quality and the oxidation explosion sweep range are calculated as follows:
in the formula, P o Original formation pressure, pa; sigma is tensile strength of the rock, pa; phi is the compact gas layer porosity; r is the oxidation explosion wave radius, pa; r is ideal gas constant, 8.314J. Mol -1 ·K -1 ；Z o Is the pre-oxidation decrepitation gas compression factor; z m Is a gas compression factor after oxidation explosion; t is o Is the original formation temperature, K; m is the hydrogen peroxide injection mass, g; m H2O2 Hydrogen peroxide molar mass, 34g/mol; m is a group of CH4 Is the molar mass of methane, 16g/mol; c is the specific heat capacity of methane, and is 2.227 kJ/(kg. K); q is the calorific value of methane when the product is gaseous water, 50200kJ/kg.
According to the formula, given m, a unary high-order equation of r is obtained and solved through a dichotomy.
In the example, the original formation pressure was 66.8MPa, the tensile strength of the rock after hydration was 6.3MPa, the original formation temperature was 393K, the average porosity was 4.17%, the gas compression factors before and after the oxidation burst were 1.2, the amount of the oxidizing solution was 5000kg (1000 kg of hydrogen peroxide), and the oxidation burst wave radius was 8.5m.
(3) Slippery water containing glue solution
The glue-containing solution slickwater is used for squeezing the oxidizing solution into the stratum from the shaft and preventing the hydrogen peroxide from reacting with the catalyst in the shaft, and the using amount of the hydrogen peroxide is 1.2 times of the volume of the shaft.
In the formula, V 2 M3 is the slick water volume of the gel-containing solution; beta is a safety coefficient, and is 1.0 to 1.5.
The parameters are the same as those in the slickwater A, and the dosage of the slickwater containing the glue is 63m 3 。
(4) Catalytic decomposition liquid
The catalytic decomposing liquid uses slickwater containing catalytic decomposing agent, the volume of which is the same as that of the oxidizing liquid, and the catalytic decomposing agent includes but is not limited to sodium hydroxide and manganese dioxide.
In the formula, V 4 M3, a catalytic decomposition liquid; rho is the density of slick water, kg/m3.
The density of the slippery water is 1000kg/m 3 5m of catalytic decomposition liquid 3 。
(5) Slick water B
And the slickwater B is used for displacing hydrogen peroxide and a catalyst into the crack, so that an oxidation burst wave and a shaft are avoided, and the integrity of the shaft is protected.
In the formula, V 5 Is the volume of slickwater B, m 3 。
The other parameters are the same as those in the slickwater A, and the dosage of the slickwater B is 136m 3 。
According to the calculation method provided by the invention, the total dosage of 373m of the oxidation bursting fracturing fluid 3 And an oxidation explosion crack net is respectively generated at the positions of 70m on two wings of the shaft, and the radius of the crack net is 8.5m.
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 (9)
1. The shale gas layer oxidation burst transformation method is characterized by comprising the following steps: the method comprises the following steps:
performing hydraulic fracturing transformation on a shale gas well to be fractured;
in the hydraulic fracturing process, slickwater A-oxidizing liquid-gel-containing liquid slickwater-catalytic decomposition liquid-slickwater B are sequentially pumped in a slug type;
the charge of slickwater a was calculated according to the following formula:
in the formula, V 1 Is the volume of slickwater A; alpha is the leakage coefficient, and 1.0-1.5 is taken; d is the outer diameter of the sleeve; delta is the wall thickness of the sleeve; h is the well depth; l is the depth of explosion point; h is the height of a main hydraulic fracture; and W is the width of the main fracture of the hydraulic fracture.
2. The shale gas layer oxidation decrepitation modification method of claim 1, wherein: the oxidizing solution is a mixed solution of hydrogen peroxide and dilute hydrochloric acid.
3. The shale gas layer oxidation burst modification method of claim 2, wherein: the hydrogen peroxide implant mass and the oxidation burst wave and radius were calculated according to the following formula:
in the formula, P o Is the original formation pressure; sigma is rock tensile strength; phi isPorosity of the dense gas layer; r is the oxidation explosion wave radius; r is an ideal gas constant; z o Is the pre-oxidation decrepitation gas compression factor; z is a linear or branched member m Is a gas compression factor after oxidation explosion; t is o Is the original formation temperature, K; m is the hydrogen peroxide injection mass; m H2O2 Is hydrogen peroxide molar mass; m CH4 Is the molar mass of methane; c is the specific heat capacity of methane; q is the heating value of methane when the product is gaseous water.
4. The shale gas layer oxidation burst modification method of claim 3, wherein: according to a calculation formula of the hydrogen peroxide injection mass and the oxidation burst wave sum radius, giving the hydrogen peroxide injection mass m, obtaining a unitary high-order equation of the oxidation burst wave sum radius r, and solving the unitary high-order equation of the oxidation burst wave sum radius r to obtain the oxidation burst wave sum radius r;
or, according to a calculation formula of the hydrogen peroxide injection mass and the oxidation burst wave sum radius, giving the oxidation burst wave sum radius r to obtain a unitary high-order equation of the hydrogen peroxide injection mass m, and solving the unitary high-order equation of the hydrogen peroxide injection mass m to obtain the hydrogen peroxide injection mass m.
5. The shale gas layer oxidation burst modification method of claim 1, wherein: the injection amount of the glue-containing liquid slickwater is larger than the effective volume of the shaft.
6. The shale gas layer oxidation decrepitation modification method of claim 1 or 5, wherein: the amount of the slick water to be injected was calculated according to the following formula:
in the formula, V 2 Is the slippery water volume of the glue-containing liquid; beta is a safety coefficient, and is 1.0-1.5; d is the outer diameter of the sleeve; delta is the casing wall thickness and h is the well depth.
7. The shale gas layer oxidation burst modification method of claim 1, wherein: the catalytic decomposition liquid is prepared by adding a catalytic decomposing agent to the slick water, wherein the catalytic decomposing agent comprises but is not limited to sodium hydroxide and manganese dioxide.
8. The shale gas layer oxidation burst modification method of claim 3, wherein: calculating the injection amount of the catalytic decomposition liquid according to the following formula:
in the formula, V 4 Is a catalytic decomposition liquid; rho is the density of the slick water; and m is the hydrogen peroxide injection mass.
9. The shale gas layer oxidation burst modification method of claim 1, wherein: the slickwater B is used for packing the oxidizing liquid, so that the local bursting in the shale hydraulic fracture is generated at the end far away from the shaft, and the integrity of the shaft is prevented from being damaged;
calculating the injection amount of the slickwater B according to the following formula:
in the formula, V 5 Is the volume of slickwater B; d is the outer diameter of the sleeve; delta is the sleeve wall thickness; h is the well depth; l is the depth of explosion point; h is the height of a main hydraulic fracture; w is the width of the main fracture of the hydraulic fracture.
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| CN115324552A (en) * | 2022-09-21 | 2022-11-11 | 中国石油天然气集团有限公司 | Fracturing and crack-making method based on chemical reaction and reservoir fracturing modification method |
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