CN117688781A - Methane blasting composite hydraulic fracturing method - Google Patents
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 422
- 238000005422 blasting Methods 0.000 title claims abstract description 149
- 239000002131 composite material Substances 0.000 title claims abstract description 103
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000010276 construction Methods 0.000 claims abstract description 115
- 238000004880 explosion Methods 0.000 claims abstract description 73
- 238000004088 simulation Methods 0.000 claims abstract description 53
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- 230000009466 transformation Effects 0.000 claims abstract description 26
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- 238000002485 combustion reaction Methods 0.000 claims abstract description 17
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- 239000012530 fluid Substances 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 15
- 238000005086 pumping Methods 0.000 claims description 12
- 239000002360 explosive Substances 0.000 claims description 9
- 239000011435 rock Substances 0.000 claims description 9
- 238000006073 displacement reaction Methods 0.000 claims description 7
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- 238000005474 detonation Methods 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 4
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- 238000000638 solvent extraction Methods 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 23
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- 238000011084 recovery Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- E—FIXED CONSTRUCTIONS
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Abstract
The invention discloses a methane blasting composite hydraulic fracturing method, which comprises the following steps: obtaining geological data of a vertical well or a horizontal well of a target reservoir; inputting the geological data into a preset geological modeling model, dividing grids, and endowing each coordinate position block unit with an attribute so as to establish a methane blasting model of a target reservoir; respectively inputting a plurality of groups of methane explosion initial values into the methane explosion model, and outputting a simulation result of the corresponding methane explosion, wherein the methane explosion initial values comprise initial values of the amount of methane substances and the ratio of methane to combustion improver; drawing a first dynamic relation diagram between methane explosion construction parameters and evaluation indexes according to an input methane explosion initial value and an output simulation result, wherein the evaluation indexes are reservoir fracture transformation volumes in the simulation result; and screening out the methane blasting construction parameters according to the first dynamic relation diagram and the transformation effect on the target reservoir.
Description
Technical Field
The invention relates to the technical field of oil and gas field exploitation, in particular to a methane blasting composite hydraulic fracturing method.
Background
With the rapid increase of energy demand in China, the production and development of domestic conventional oil and gas reservoirs cannot meet the requirements of domestic economic high-speed development, deep reservoirs have the characteristics of high confining pressure, high stress difference, high fracture pressure and the like, and the problems of non-fracture, difficult crack initiation, single crack form, small reservoir modification volume and the like easily occur in conventional hydraulic fracturing modification. The explosion fracturing technology has the advantages of simple operation, high peak pressure, breakthrough of the concentration of the earth stress around the well, formation of a complex fracture network which is not controlled by the earth stress, and the like, and can be just suitable for the front induced fracturing of the deep unconventional reservoir hydraulic fracturing.
Based on the above, researchers have proposed a kind of compound fracturing yield increasing technological method that combines the explosion fracturing and hydraulic fracturing, namely first produce the radial self-supporting crack that is not controlled by the ground stress in the interval of goal, reduce Zhou Polie pressure of well and subsequent hydraulic fracturing and initiate the pressure of cracking at the same time, then carry on the hydraulic fracturing of large discharge capacity, form near-well multi-crack, far-well multi-main comprehensive transformation effect of seam, thus improve the single well reservoir transformation volume of unconventional reservoir effectively, and then improve the single well output.
The methane in-situ blasting fracturing technology is used as the latest technology, methane naturally produced in adjacent gas wells is used as fuel, and methane and different kinds of combustion promoters are injected into a reservoir to achieve a preset proportion and blasting pressure, so that peak pressure and pressure loading rate lower than blasting fracturing but higher than conventional hydraulic fracturing are generated in a shaft, a self-supporting near-well multi-fracture system is generated, the near-well fracture diversion capability is improved, and the novel technology is used for promoting efficient development of shale gas in China. The method has the advantages of no water, no propping agent, no pollution, low cost, no need of manually implanting other blasting materials, low construction risk and the like. However, how to efficiently and economically finish the methane blasting composite hydraulic fracturing construction of specific well in the oilfield site is a great difficulty, and the optimization design of specific construction parameters in the methane blasting composite hydraulic fracturing process is not yet perfect.
The foregoing is provided merely for the purpose of facilitating understanding of the technical solutions of the present invention and is not intended to represent an admission that the foregoing is prior art.
Disclosure of Invention
The invention mainly aims to provide a methane blasting composite hydraulic fracturing method which aims to solve the problems.
In order to achieve the above purpose, the invention provides a methane blasting composite hydraulic fracturing method, which comprises the following steps:
obtaining geological data of a vertical well or a horizontal well of a target reservoir;
inputting the geological data into a preset geological modeling model, dividing grids, and endowing each coordinate position block unit with an attribute so as to establish a methane blasting model of a target reservoir;
respectively inputting a plurality of groups of methane explosion initial values into the methane explosion model, and outputting a simulation result of the corresponding methane explosion, wherein the methane explosion initial values comprise initial values of the amount of methane substances and the ratio of methane to combustion improver;
drawing a first dynamic relation diagram between methane explosion construction parameters and evaluation indexes according to an input methane explosion initial value and an output simulation result, wherein the evaluation indexes are reservoir fracture transformation volumes in the simulation result;
screening out methane blasting construction parameters according to the first dynamic relation diagram and the transformation effect of the target reservoir;
inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, and repartitioning grids to establish a hydraulic fracturing initial model;
inputting a plurality of groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir in the initial hydraulic fracturing model respectively, and outputting a corresponding methane blasting composite hydraulic fracturing simulation result, wherein the initial construction parameters comprise initial pumping displacement and initial fracturing fluid viscosity;
drawing a second dynamic relation diagram of the construction parameters and the methane blasting composite hydraulic fracturing simulation result according to the input multiple groups of initial construction parameters and the methane blasting composite hydraulic fracturing simulation result;
screening out the construction parameters of methane combustion and explosion composite hydraulic fracturing according to the second dynamic relation diagram;
and carrying out methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters.
Preferably, in the methane blasting composite hydraulic fracturing method, the step of performing methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters comprises the following steps:
determining key parameters of methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters;
and carrying out methane blasting composite hydraulic fracturing construction according to the key parameters.
Preferably, in the methane-explosion composite hydraulic fracturing method, the step of inputting the geological data into a preset geological modeling model and dividing grids to endow each coordinate position with block unit attribute so as to establish a methane-explosion model of a target reservoir comprises the following steps:
inputting the geological data into a preset geological modeling model, endowing each coordinate position block unit attribute with a partitioning network, and establishing a methane blasting model of a target reservoir based on the Langdao blasting source model.
Preferably, in the methane-explosion composite hydraulic fracturing method, the Langdao source model comprises two stages, namely a high-pressure expansion stage and a low-pressure expansion stage, and the formula is as follows:
；
wherein,；
；
gamma and gamma 1 Taking 3 and 4/3 for adiabatic indexes respectively;
p、p 0 and p k The real-time pressure, the average detonation pressure and the two-section adiabatic expansion process limit pressure of the explosive gas are respectively shown in Pa;
V、V 0 and V k Respectively the real-time volume of the explosive gas, the initial volume of the explosive source and the limit volume of two adiabatic expansion processes, and the unit m 3 ；
p w The pressure of methane gas in the explosion source space before explosion is shown as a unit Pa;
m is the molar mass of methane, in g/mol;
d is the explosion speed, and the unit is m/s;
r is an ideal gas constant, and takes on a value 8.314;
t is the thermodynamic temperature, unit K;
Q w the heat of detonation per unit mass, unit J/kg.
Preferably, in the methane blasting composite hydraulic fracturing method, the geological data comprises the depth and thickness of a target reservoir, three-way ground stress, the permeability of a reservoir matrix, physical and mechanical parameters of stratum rock and natural fracture parameters.
Preferably, in the methane blasting composite hydraulic fracturing method, the step of inputting the screened methane blasting construction parameters, the wellbore parameters and the geological data into a preset geological modeling model and repartitioning grids to establish a hydraulic fracturing initial model comprises the following steps:
inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, re-dividing grids, and adding flow boundary conditions formed by the KGD hydraulic fracturing model to establish a hydraulic fracturing initial model;
wherein, KGD hydraulic fracturing model includes:
；
l (t) is the half length of the split seam;
t is time;
W 0 (t) is the width of the seam at the wellhead;
v is the rock poisson ratio;
e is a rock matrix elastic model, gpa;
μ is the fracturing fluid viscosity, mpa.s;
q 0 for pumping speed of fracturing fluid, m 3 /s。
Preferably, in the methane blasting composite hydraulic fracturing method, multiple groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir are respectively input into the hydraulic fracturing initial model, and in the step of outputting a corresponding methane blasting composite hydraulic fracturing simulation result, the methane blasting composite hydraulic fracturing simulation result comprises a composite fracturing reservoir transformation volume.
Preferably, in the methane blasting composite hydraulic fracturing method, the step of screening the methane blasting composite hydraulic fracturing construction parameters according to the second dynamic relation diagram includes:
screening out the methane blasting composite hydraulic fracturing construction parameters according to the second dynamic relation diagram and a preset rule;
the preset rule comprises that the value of the optimal composite fracturing reservoir reconstruction volume is 1.0-1.2 times of the preset reservoir reconstruction volume of the adjacent well of the same oil field block; and determining the construction parameters of the screened methane blasting composite hydraulic fracturing according to the transformation volume of the optimal composite fracturing reservoir.
The invention has at least the following beneficial effects:
the geological data of a vertical well or a horizontal well of a target reservoir are obtained; inputting the geological data into a preset geological modeling model, dividing grids, and endowing each coordinate position block unit with an attribute so as to establish a methane blasting model of a target reservoir; respectively inputting a plurality of groups of methane explosion initial values into the methane explosion model, and outputting a simulation result of the corresponding methane explosion, wherein the methane explosion initial values comprise initial values of the amount of methane substances and the ratio of methane to combustion improver; drawing a first dynamic relation diagram between methane explosion construction parameters and evaluation indexes according to an input methane explosion initial value and an output simulation result, wherein the evaluation indexes are reservoir fracture transformation volumes in the simulation result; screening out methane blasting construction parameters according to the first dynamic relation diagram and the transformation effect of the target reservoir; inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, and repartitioning grids to establish a hydraulic fracturing initial model; inputting a plurality of groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir in the initial hydraulic fracturing model respectively, and outputting a corresponding methane blasting composite hydraulic fracturing simulation result, wherein the initial construction parameters comprise initial pumping displacement and initial fracturing fluid viscosity; drawing a second dynamic relation diagram of the construction parameters and the methane blasting composite hydraulic fracturing simulation result according to the input multiple groups of initial construction parameters and the methane blasting composite hydraulic fracturing simulation result; screening out the construction parameters of methane combustion and explosion composite hydraulic fracturing according to the second dynamic relation diagram; and carrying out methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters, so that the methane blasting composite hydraulic fracturing construction of specific well times is completed with high efficiency and high economic benefit, and the specific construction parameters in the methane blasting composite hydraulic fracturing process are optimally designed.
Further, through drilling and logging data of the earlier exploratory well, a sufficiently large reservoir geological three-dimensional numerical model is established, and the optimal fracturing construction scale with the most economic benefit after the fracturing cost is considered is optimized, so that the full utilization of a reservoir is ensured, and the yield and recovery ratio of deep reservoir shale gas reservoirs and tight reservoirs are effectively improved.
Furthermore, the conventional hydraulic fracturing can only press a long main seam perpendicular to the horizontal minimum main stress, the crack shape is single, and the reservoir transformation volume is smaller; the methane blasting composite hydraulic fracturing technology provided by the invention can effectively reduce the fracturing pressure near the well wall, form near-well multi-crack and far-well multi-main-crack comprehensive transformation effects, and effectively increase the transformation volume of a reservoir. According to the related field application practice, on the premise of the same fracturing fluid discharge capacity and fracturing construction cost, after the methane blasting composite hydraulic fracturing technology is applied to a single well, the daily oil yield increase of the single well is 1.5-2 times that of the single well in the same block well subjected to conventional hydraulic fracturing, and under the condition of the same fracturing cost, the single well yield increase effect is extremely remarkable.
Drawings
FIG. 1 is a schematic diagram of the methane blasting fracturing simulation parameter optimization of the invention;
FIG. 2 is a graph of the dynamic relationship between the volume of the layer reform and the fracturing fluid dosage of the present invention;
FIG. 3 is a schematic diagram of the composite fracturing simulation results of the present invention;
fig. 4 is a flow chart of the methane blasting composite hydraulic fracturing method provided by the invention.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
In the embodiment of the invention, the term "and/or" describes the association relation of the association objects, which means that three relations can exist, for example, a and/or B can be expressed as follows: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
The term "plurality" in embodiments of the present invention means two or more, and other adjectives are similar.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be understood by those of ordinary skill in the art that in various embodiments of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the claimed technical solution of the present invention can be realized without these technical details and various changes and modifications based on the following embodiments. The following embodiments are divided for convenience of description, and should not be construed as limiting the specific implementation of the present invention, and the embodiments can be mutually combined and referred to without contradiction.
The invention provides a methane blasting composite hydraulic fracturing method, referring to fig. 1, comprising the following steps:
step S01, geological data of a vertical well or a horizontal well of a target reservoir are obtained;
in particular, basic exploration and three-dimensional geological data of a vertical or horizontal well of a target reservoir may be obtained from drilling and logging data to obtain geological data of the vertical or horizontal well of the target reservoir, wherein the geological data includes, but is not limited to, reservoir depth and thickness of interest, three-way earth stress, reservoir matrix permeability, formation petrophysical mechanical parameters (Young's modulus Poisson's ratio), natural fracture parameters, and the like.
Step S02, inputting the geological data into a preset geological modeling model, dividing grids, and endowing each coordinate position block unit with an attribute so as to establish a methane blasting model of a target reservoir;
it should be understood that the preset geologic modeling model may be, but is not limited to, a mechanical model, such as GDEM, which may be a national institute of mechanical software, academy of sciences, china. The GDEM software is composed of a CDEM continuous-discontinuous model, wherein basic units are divided into blocks and interfaces, grids are divided among the block units, the grids are cut to form a virtual interface, and a pull-shear half spring is arranged on the interface unit and used for transmitting mechanical information and realizing material fracture expansion simulation. And judging that cracks appear when the springs are broken.
More specifically, the step S02 includes:
and step S021, inputting the geological data into a preset geological modeling model, endowing each coordinate position block unit attribute with a partitioning network, and establishing a methane explosion model of the target reservoir based on the Langdao explosion source model.
The invention establishes the methane blasting model of the target reservoir based on the Lang-channel blasting source model, and takes the condition limited by the Lang-channel blasting source model as a limiting condition.
More specifically, the Landmark explosion source model takes methane explosion as an adiabatic expansion process by neglecting heat exchange between explosion gas and surrounding medium, and the limiting condition of the Landmark explosion source model comprises two stages, namely a high-pressure expansion stage (p > p k ) And a low pressure expansion stage (p < p) k ) The formula is as follows:
；
wherein,；
；
gamma and gamma 1 Taking 3 and 4/3 for adiabatic indexes respectively;
p、p 0 and p k The real-time pressure, the average detonation pressure and the two-section adiabatic expansion process limit pressure of the explosive gas are respectively shown in Pa;
V、V 0 and V k Respectively the real-time volume of the explosive gas, the initial volume of the explosive source and the limit volume of two adiabatic expansion processes, and the unit m 3 ；
p w The pressure of methane gas in the explosion source space before explosion is shown as a unit Pa;
m is the molar mass of methane, in g/mol;
d is the explosion speed, and the unit is m/s;
r is an ideal gas constant, and takes on a value 8.314;
t is the thermodynamic temperature, unit K;
Q w the heat of detonation per unit mass, unit J/kg.
In addition, the methane blasting process can be approximately understood as:
determination of gamma 1 、γ、T、Q w Waiting for thermodynamic parameters of the methane explosion; then, by inputting the shaft volume and methane volume in the initial state, each parameter p of methane burning and explosion in the initial state is determined w 、p k 、M、V、V k Thus obtaining the methane explosion parameters p and V of the next time step. And then the calculation of the next time step is sequentially carried out, so that the methane explosion simulation of the whole process is completed.
S03, respectively inputting a plurality of groups of methane explosion initial values into the methane explosion model, and outputting a simulation result of the corresponding methane explosion, wherein the methane explosion initial values comprise initial values of the amount of methane substances and the ratio of methane to combustion improver;
it should be understood that two parameters of an initial value of the amount of methane substances and an initial value of the ratio of methane to combustion improver are input into the methane explosion model, and the numerical simulation of methane explosion fracturing of the whole process is sequentially carried out from 0s time step to time step. And finally outputting two simulation result values of the crack expansion form of the secondary methane explosion fracturing, namely the pressure of the well Zhou Polie after explosion and the reservoir crack transformation volume.
Assuming the explosion is a constant volume adiabatic process, the calculation of the initial methane species n can be based on the corrected gas state equation:
；
p is the pressure of the mixed gas, and can be approximately replaced by the pore pressure of the stratum and MPa;
v is the volume of the shaft, m 3 ；
Z is a gas compression factor, dimensionless;
n is the amount of methane gas species, mol;
r is the molar gas constant, J/(mol.K);
t is the temperature of the mixed gas and can be approximately replaced by the formation temperature, K.
In the step 03, the 'stage 1' blasting fracturing simulation is divided into two stages, and the total blasting time is 303ms by default, wherein the blasting stress impact stage is 3ms, and the blasting high-energy gas leakage stage is 300ms.
And (3) repeatedly performing the numerical simulation of the methane blasting fracturing construction in the step 03 by continuously adjusting two construction parameters of the amount of the input methane substances and the ratio of the methane to the combustion improver, and repeatedly outputting a plurality of groups of simulation result numerical values.
Step S04, drawing a first dynamic relation diagram between methane blasting construction parameters and evaluation indexes according to an input methane blasting initial value and an output simulation result, wherein the evaluation indexes are reservoir fracture transformation volumes in the simulation result;
it should be understood that, as shown in fig. 1, two evaluation indexes are illustrated in fig. 1. Because the points are input, the relation between the methane blasting construction parameters and the evaluation indexes can be determined according to the first dynamic relation diagram by drawing the first dynamic relation diagram. In other embodiments, the reservoir fracture transformation volume is used as a main evaluation index, other values are used as secondary evaluation indexes, and a dynamic relation diagram between the alkane blasting construction parameters and the evaluation indexes is drawn.
Step S05, screening out methane blasting construction parameters according to the first dynamic relation diagram and the reconstruction effect of the target reservoir;
it should be understood that the screening of the methane blasting construction parameters is mainly performed according to the transformation effect of the target reservoir, and one or more groups of methane blasting construction parameters with the best transformation effect of the target reservoir are screened.
The construction parameters of methane blasting can be screened according to the best economic benefit. And the construction parameters of methane blasting fracturing with the best economic benefit and reservoir reconstruction effect are optimized. The chemical reaction equation for methane explosion is known as CH 4 +2O 2 ＝CO 2 +2H 2 O, the reaction enthalpy value is 802kJ/mol. With oxygen, hydrogen and a small amount of liquid N 2 O 4 For the example of mixing combustion improver, the method comprises the following steps of CH 4 ：O 2 ：H 2 Initial ratio =2:4:1, amount of n moles of initial methane material, methane flame-explosion fracture propagation numerical simulation was performed. And then gradually increasing the amount of the methane substances, taking the initial fracture reservoir transformation volume as a main evaluation index, drawing a dynamic relation graph, and preferably taking two construction parameters of the optimal methane substance amount and the ratio of methane to combustion improver after the cost and the reservoir transformation effect into consideration, and outputting and storing the result.
Step S06, inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, and re-dividing grids to establish a hydraulic fracturing initial model;
specifically, the step S06 includes:
inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, re-dividing grids, and adding flow boundary conditions formed by the KGD hydraulic fracturing model to establish a hydraulic fracturing initial model;
wherein, KGD hydraulic fracturing model includes:
；
l (t) is the half length of the split seam;
t is time;
W 0 (t) is the width of the seam at the wellhead;
v is the rock poisson ratio;
e is a rock matrix elastic model, gpa;
μ is the fracturing fluid viscosity, mpa.s;
q 0 for pumping speed of fracturing fluid, m 3 /s。
More specifically, the screened methane blasting construction parameters, the well bore parameters and the geological data are imported into the GDEM software again, the grids are divided again, KGD hydraulic fracturing flow boundary conditions are added, and therefore the hydraulic fracturing initial model is built.
The KGD is a two-dimensional model of classical hydraulic fracturing, the vertical fracture is assumed to be a single-fracture model of equal-height fracture, the horizontal section of the fracture meets plane strain conditions Geertsma and DeKlerk, and the evolution relationship of the fracture half length and the wellhead seam width along with time in the KGD model is deduced as follows:
；
wherein: e is a rock matrix elastic model, gpa;
mu is the viscosity of fracturing fluid, mPa.s;
q 0 for pumping speed of fracturing fluid, m 3 /s。
S07, respectively inputting a plurality of groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir in the initial hydraulic fracturing model, and outputting a corresponding methane blasting composite hydraulic fracturing simulation result, wherein the initial construction parameters comprise initial pumping displacement and initial fracturing fluid viscosity;
in this embodiment, the methane blasting composite hydraulic fracturing simulation result includes a composite fracturing reservoir remodel volume.
Step S08, drawing a second dynamic relation diagram of the construction parameters and the methane blasting composite hydraulic fracturing simulation result according to the input multiple groups of initial construction parameters and the methane blasting composite hydraulic fracturing simulation result;
it should be understood that as shown in fig. 2, the dynamic relationship of the methane blasting composite hydraulic fracturing construction parameters (such as the amount of fracturing fluid) to the methane blasting composite hydraulic fracturing simulation results (reservoir reform volume) is shown.
Step S09, screening out the construction parameters of methane blasting composite hydraulic fracturing according to the second dynamic relation diagram;
more specifically, step S09 includes the step of screening the methane-blasting composite hydraulic fracturing construction parameters according to the second dynamic relationship diagram, where the step of screening the methane-blasting composite hydraulic fracturing construction parameters includes:
screening out the methane blasting composite hydraulic fracturing construction parameters according to the second dynamic relation diagram and a preset rule;
the preset rule comprises that the value of the optimal composite fracturing reservoir reconstruction volume is 1.0-1.2 times of the preset reservoir reconstruction volume of the adjacent well of the same oil field block; and determining the construction parameters of the screened methane blasting composite hydraulic fracturing according to the transformation volume of the optimal composite fracturing reservoir.
And S10, performing methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters.
More specifically, step S10 includes:
determining key parameters of methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters;
and carrying out methane blasting composite hydraulic fracturing construction according to the key parameters.
It should be noted that, according to field experience, the value of the optimal reservoir reconstruction volume is 1.0-1.2 times the predetermined reservoir reconstruction volume of the adjacent wells of the same oilfield block. On the premise, the smaller the pumping displacement, the larger the initial fracturing fluid viscosity, and the more suitable.
The geological data of a vertical well or a horizontal well of a target reservoir are obtained; inputting the geological data into a preset geological modeling model, dividing grids, and endowing each coordinate position block unit with an attribute so as to establish a methane blasting model of a target reservoir; respectively inputting a plurality of groups of methane explosion initial values into the methane explosion model, and outputting a simulation result of the corresponding methane explosion, wherein the methane explosion initial values comprise initial values of the amount of methane substances and the ratio of methane to combustion improver; drawing a first dynamic relation diagram between methane explosion construction parameters and evaluation indexes according to an input methane explosion initial value and an output simulation result, wherein the evaluation indexes are reservoir fracture transformation volumes in the simulation result; screening out methane blasting construction parameters according to the first dynamic relation diagram and the transformation effect of the target reservoir; inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, and repartitioning grids to establish a hydraulic fracturing initial model; inputting a plurality of groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir in the initial hydraulic fracturing model respectively, and outputting a corresponding methane blasting composite hydraulic fracturing simulation result, wherein the initial construction parameters comprise initial pumping displacement and initial fracturing fluid viscosity; drawing a second dynamic relation diagram of the construction parameters and the methane blasting composite hydraulic fracturing simulation result according to the input multiple groups of initial construction parameters and the methane blasting composite hydraulic fracturing simulation result; screening out the construction parameters of methane combustion and explosion composite hydraulic fracturing according to the second dynamic relation diagram; and carrying out methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters, so that the methane blasting composite hydraulic fracturing construction of specific well times is completed with high efficiency and high economic benefit, and the specific construction parameters in the methane blasting composite hydraulic fracturing process are optimally designed.
Further, through drilling and logging data of the earlier exploratory well, a sufficiently large reservoir geological three-dimensional numerical model is established, and the optimal fracturing construction scale with the most economic benefit after the fracturing cost is considered is optimized, so that the full utilization of a reservoir is ensured, and the yield and recovery ratio of deep reservoir shale gas reservoirs and tight reservoirs are effectively improved.
Examples
Table 1 geological data of shale gas well logs at a burial depth of 2900m
Natural cracks do not develop.
Simulation process and results:
a two-dimensional vertical well crack propagation model of 100m multiplied by 40m is firstly established aiming at a deep shale reservoir, a central position is set as a well hole, the diameter is 0.16m, methane explosion composite hydraulic fracturing under the condition of open hole completion is simulated, and a well hole space is set as an explosion source. And optimizing construction parameters such as methane concentration, combustion improver proportion and the like of the methane blasting by methane blasting fracturing simulation. Initializing a numerical model, introducing an optimal methane explosion fracturing crack expansion grid as an initial grid, performing hydraulic fracturing simulation, and optimizing pumping parameters such as optimal fracturing liquid pumping discharge capacity, viscosity and the like through the hydraulic fracturing simulation to ensure that the ratio of single well productivity to the total discharge capacity of the fracturing liquid is optimal, thereby optimizing the methane explosion composite hydraulic fracturing construction parameters with the most economic benefit after the fracturing cost is considered.
Table 2 methane blasting fracturing screening parameters
| Parameter name | Numerical value |
| Combustion improver formula | CH 4 ：O 2 ：H 2 =2:6:1 |
| Methane concentration | 33.2mol/m 3 |
| Methane material quantity | 4.98mol |
Table 3 hydraulic fracture screening parameters
| Parameter name | Numerical value |
| Fracturing fluid displacement (m) 3 /min) | 4.8 |
| Viscosity of fracturing fluid (mPa. S) | 50*10 -3 |
It will be apparent that the embodiments described above are merely some, but not all, embodiments of the invention. Based on the embodiments of the present invention, those skilled in the art may make other different changes or modifications without making any creative effort, which shall fall within the protection scope of the present invention.
Claims (8)
1. The methane blasting composite hydraulic fracturing method is characterized by comprising the following steps of:
obtaining geological data of a vertical well or a horizontal well of a target reservoir;
inputting the geological data into a preset geological modeling model, dividing grids, and endowing each coordinate position block unit with an attribute so as to establish a methane blasting model of a target reservoir;
respectively inputting a plurality of groups of methane explosion initial values into the methane explosion model, and outputting a simulation result of the corresponding methane explosion, wherein the methane explosion initial values comprise initial values of the amount of methane substances and the ratio of methane to combustion improver;
drawing a first dynamic relation diagram between methane explosion construction parameters and evaluation indexes according to an input methane explosion initial value and an output simulation result, wherein the evaluation indexes are reservoir fracture transformation volumes in the simulation result;
screening out methane blasting construction parameters according to the first dynamic relation diagram and the transformation effect of the target reservoir;
inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, and repartitioning grids to establish a hydraulic fracturing initial model;
inputting a plurality of groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir in the initial hydraulic fracturing model respectively, and outputting a corresponding methane blasting composite hydraulic fracturing simulation result, wherein the initial construction parameters comprise initial pumping displacement and initial fracturing fluid viscosity;
drawing a second dynamic relation diagram of the construction parameters and the methane blasting composite hydraulic fracturing simulation result according to the input multiple groups of initial construction parameters and the methane blasting composite hydraulic fracturing simulation result;
screening out the construction parameters of methane combustion and explosion composite hydraulic fracturing according to the second dynamic relation diagram;
and carrying out methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters.
2. The methane blasting composite hydraulic fracturing method according to claim 1, wherein the step of performing methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters comprises the steps of:
determining key parameters of methane blasting composite hydraulic fracturing construction according to the screened methane blasting construction parameters and the methane blasting composite hydraulic fracturing construction parameters;
and carrying out methane blasting composite hydraulic fracturing construction according to the key parameters.
3. The methane-blasting composite hydraulic fracturing method of claim 1, wherein the step of inputting the geological data into a preset geological modeling model and meshing to give each coordinate position block unit attribute to establish a methane-blasting model of a target reservoir comprises the steps of:
inputting the geological data into a preset geological modeling model, endowing each coordinate position block unit attribute with a partitioning network, and establishing a methane blasting model of a target reservoir based on the Langdao blasting source model.
4. The methane-blasting composite hydraulic fracturing method of claim 3, wherein the langerhans blasting source model comprises two stages, namely a high-pressure expansion stage and a low-pressure expansion stage, and the formula is as follows:
；
wherein,；
；
gamma and gamma 1 Taking 3 and 4/3 for adiabatic indexes respectively;
p、p 0 and p k The real-time pressure, the average detonation pressure and the two-section adiabatic expansion process limit pressure of the explosive gas are respectively shown in Pa;
V、V 0 and V k Respectively the real-time volume of the explosive gas, the initial volume of the explosive source and the limit volume of two adiabatic expansion processes, and the unit m 3 ；
p w The pressure of methane gas in the explosion source space before explosion is shown as a unit Pa;
m is the molar mass of methane, in g/mol;
d is the explosion speed, and the unit is m/s;
r is an ideal gas constant, and takes on a value 8.314;
t is the thermodynamic temperature, unit K;
Q w the heat of detonation per unit mass, unit J/kg.
5. The methane-blasting composite hydraulic fracturing method of claim 1, wherein the geological data comprises depth and thickness of a target reservoir, three-way ground stress, reservoir matrix permeability, physical mechanical parameters of formation rock, natural fracture parameters.
6. The methane blasting composite hydraulic fracturing method of claim 1, wherein the step of inputting the screened methane blasting construction parameters, the wellbore parameters, and the geological data into a preset geological modeling model and repartitioning grids to establish a hydraulic fracturing initial model comprises the steps of:
inputting the screened methane blasting construction parameters, the well bore parameters and the geological data into a preset geological modeling model, re-dividing grids, and adding flow boundary conditions formed by the KGD hydraulic fracturing model to establish a hydraulic fracturing initial model;
wherein, KGD hydraulic fracturing model includes:
；
l (t) is the half length of the split seam;
t is time;
W 0 (t) is the width of the seam at the wellhead;
v is the rock poisson ratio;
e is a rock matrix elastic model, gpa;
μ is the fracturing fluid viscosity, mpa.s;
q 0 for pumping speed of fracturing fluid, m 3 /s。
7. The methane-blasting composite hydraulic fracturing method according to claim 1, wherein in the step of inputting a plurality of groups of initial construction parameters of a vertical well or a horizontal well of a target reservoir in the hydraulic fracturing initial model and outputting a corresponding methane-blasting composite hydraulic fracturing simulation result, the methane-blasting composite hydraulic fracturing simulation result comprises a composite fracturing reservoir reconstruction volume.
8. The methane-blasting composite hydraulic fracturing method of claim 1, wherein the step of screening out the methane-blasting composite hydraulic fracturing construction parameters according to the second dynamic relationship diagram comprises:
screening out the methane blasting composite hydraulic fracturing construction parameters according to the second dynamic relation diagram and a preset rule;
the preset rule comprises that the value of the optimal composite fracturing reservoir reconstruction volume is 1.0-1.2 times of the preset reservoir reconstruction volume of the adjacent well of the same oil field block; and determining the construction parameters of the screened methane blasting composite hydraulic fracturing according to the transformation volume of the optimal composite fracturing reservoir.
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