CN113356843B - Method, device, medium and equipment for analyzing stability of well wall of stratum - Google Patents
Method, device, medium and equipment for analyzing stability of well wall of stratum Download PDFInfo
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- CN113356843B CN113356843B CN202110739259.8A CN202110739259A CN113356843B CN 113356843 B CN113356843 B CN 113356843B CN 202110739259 A CN202110739259 A CN 202110739259A CN 113356843 B CN113356843 B CN 113356843B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/06—Measuring temperature or pressure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
Abstract
The invention relates to a method, a device, a medium and equipment for analyzing the stability of a well wall of a stratum, comprising the following steps: 1) Collecting stratum directional pressure parameters; 2) Obtaining a core sample of a target stratum, and determining a stress-strain constitutive relation through experiments; 3) Describing the initial ground stress state and geomechanical characteristics of the stratum based on the stress-strain constitutive relation; 4) Establishing a three-dimensional non-structural geometric grid, and determining the space geometric parameters of a well wall stability model; 5) Forming an initial three-dimensional geomechanical model; 6) Establishing a theoretical model based on the directional parameters of the stratum; 7) Based on the characteristic of single physical field space-time evolution, well wall stability analysis under the coupling and cooperation of multiple physical fields is realized; 8) Performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite element method; 9) Quantitatively analyzing the possibility of instability of the well wall; 10 Helping the oilfield on-site to optimize drilling parameters.
Description
Technical Field
The invention relates to a method, a device, a medium and equipment for analyzing the stability of a well wall of a stratum, in particular to a method, a device, a medium and equipment for analyzing the stability of a well wall of a fluid-solid-thermal multi-field coupling well wall of a stratum under a high-temperature high-stress stratum environment, and belongs to the technical field of well wall stability of deep and ultra-deep stratum.
Background
Safe and efficient drilling and production of deep and ultra-deep oil and gas reservoirs are important ways for relieving the dependence of China on external crude oil and natural gas. However, the reservoir has the characteristics of high temperature, high stress, high formation pressure and the like, and compared with a shallow reservoir, the phenomenon of coupling action of various physical fields is more obvious, the mechanism for degrading the mechanical properties of rock around a well and the stress response rule are more complex, the phenomena of low drilling efficiency, unstable well wall and the like are more easy to occur in the development process, the risks of lost circulation, collapse of the well wall and the like are higher, and the analysis difficulty of the well wall stability is higher.
Accurate and comprehensive well wall stability analysis is a key for realizing safe and efficient well drilling. The method selects corresponding strength criteria and a constitutive model according to stratum characteristics and develops well wall stability analysis, can quantitatively describe engineering response of stress fields, pressure fields and temperature fields in surrounding rocks of a well to a drilling process, predicts complex conditions such as collapse, necking, leakage and the like caused by well wall instability, and improves the reliability of calculation of a drilling mud density window.
The common well wall stability analysis method characterizes the stress redistribution and stress concentration conditions of the well wall surrounding rock through an elastic mechanical method, a failure criterion and the like, and determines whether shearing failure, tensile failure and the like occur. The model is used for describing the space-time evolution rule of the solid mechanical field of the surrounding rock and the fluid seepage characteristics of the pores of the surrounding rock so as to realize the modeling analysis of fluid-solid coupling. However, for deep and ultra-deep formations, due to the high action temperature of the geothermal gradient, thermal strain and heat transfer occur due to the influence of thermal-solid coupling and flow-thermal coupling on the stress field and the pressure field, and meanwhile, rock elastic parameters are changed, so that the accuracy and adaptability of the conventional flow-solid coupling well wall stability method in such a scene are limited. In order to improve the stability analysis accuracy of the well wall of the deep stratum well drilling and the safety and efficiency of the well drilling, a fluid-solid-thermal multi-field coupling well wall stability analysis method aiming at the high-temperature and high-stress stratum needs to be provided.
Disclosure of Invention
Aiming at the outstanding problems, the invention provides a method, a device, a medium and equipment for analyzing the stability of a fluid-solid-thermal multi-field coupling well wall of a high-temperature high-stress stratum, which are used for analyzing the conditions of rock stress redistribution, rock damage, pore pressure field evolution and temperature distribution around the well caused by drilling, improving the calculation precision of the well collapse, diameter reduction and fracture process, optimizing the density window of drilling mud and reducing the risk of well wall instability in drilling engineering.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method for analyzing the stability of a fluid-solid-thermal multi-field coupling well wall for a stratum comprises the following steps:
1) Defining the geological condition of a target stratum, and collecting rock mechanical parameters, well depth structural design parameters and pore fluid temperature and pressure parameters of the target stratum;
2) Obtaining a core sample of a target stratum area, determining rock strength parameters and elasticity parameters of a certain depth and a horizon through an indoor triaxial mechanical experiment, and determining a stress-strain constitutive relation;
3) Based on the stress-strain constitutive relation in the step 2), calibrating and correcting aiming at the rock mechanics interpretation result and the three-dimensional geologic body model of the logging data in the target stratum region, and describing the initial ground stress state and geomechanical characteristics of the three-dimensional space of the target stratum;
4) Based on the initial ground stress state and the geomechanical characteristics in the step 3), establishing a three-dimensional non-structural geometric grid conforming to the geomechanical and physical characteristics of the stratum, and determining the space geometric parameters of a well wall stability model;
5) Optimizing three-dimensional space grid subdivision by utilizing the non-structural grids based on the three-dimensional non-structural geometric grids constructed in the step 4) to form an initial three-dimensional geomechanical model;
6) Respectively establishing theoretical models for representing the seepage field, the temperature field and the stress field space-time evolution law based on the seepage mechanical parameters, the thermodynamic parameters and the rock mechanical parameters of the target stratum, the space geometric parameters in the step 4) and the initial three-dimensional geomechanical model in the step 5);
7) Based on the theoretical model of the single physical field space-time evolution rule characterized in the step 6), further establishing a thermal-flow coupling, a flow-solid coupling and a thermal-solid coupling mechanism control equation to realize well wall stability analysis under the conditions of multi-physical field coupling and synergy;
8) Forming a multi-physical field coupling partial differential equation set aiming at stratum based on the theoretical model of the seepage field, the temperature field and the stress field space-time evolution law in the step 6) and the coupling mechanism equation in the step 7), performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite element method on the basis, performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite difference method, and further solving pressure, stress and temperature;
9) Based on actual engineering requirements of a target stratum area, calculating dynamic response characteristics of rock stress around a well under a certain range of drilling fluid density, analyzing the influence of temperature, pressure and stratum rock mechanical characteristics on the dynamic response characteristics, determining a mechanical characteristic degradation area and range, and quantitatively analyzing the possibility of well wall instability;
10 Based on the theoretical model of the seepage field, the temperature field and the stress field space-time evolution law in the step 6), carrying out parameter sensitivity analysis, respectively carrying out analysis on geological parameters and engineering parameters, determining the influence mode and the influence degree of each geological parameter and engineering parameter on the stability of the well wall, determining the parameters playing a main control role, and helping the oilfield site to carry out well drilling parameter optimization.
In the method for analyzing stability of the fluid-solid-thermal multi-field coupling well wall, preferably, the theoretical model of the time-space evolution rule of the seepage field, the temperature field and the stress field in the step 5) comprises the following control equation:
seepage field control equation:
temperature field control equation:
stress field control equation:
wherein phi is the porosity of surrounding rock of the well wall; ρ i Is pore fluid density; t is time;
is Hamiltonian; u (u) is Is the pore fluid flow rate; q i Flow rate for drilling fluid to the formation; c r Is specific heat; t is the temperature; lambda is the coefficient of thermal conductivity; q h Is a heat source and a heat sink; sigma is the second order stress tensor; wherein the pore fluid flow rate u is By->
Obtaining, wherein k is the porosity of surrounding rock of the well wall; mu (mu) i Is the viscosity of the fluid; p is formation pore pressure; g is gravity acceleration; z is the depth of the deep formation.
In the method for analyzing stability of the fluid-solid-thermal multi-field coupling well wall, preferably, the control equations of the thermal-fluid coupling, fluid-solid coupling and thermal-solid coupling mechanisms in the step 6) are specifically as follows:
thermal-flow coupling mechanism:
flow-solid coupling mechanism:
thermal-solid coupling mechanism:
ε ij ＝α(T)·(T-T 0 )
wherein, c i Is the specific heat capacity of the fluid; u (u) s Is the rock deformation speed; epsilon ij Is a thermal strain; alpha is the thermal expansion systemA number; t (T) 0 Is the reference temperature.
The fluid-solid-thermal multi-field coupling well wall stability analysis method is characterized in that the geological parameters in the step 10) comprise formation porosity, permeability, thickness, in-situ stress and formation fluid physical properties, and the engineering parameters comprise borehole size, borehole structure, drilling mud density and drilling time.
The invention also provides a device for analyzing the stability of the fluid-solid-thermal multi-field coupling well wall, which comprises the following components:
the first processing unit is used for defining the geological condition of the target stratum and collecting the rock mechanical parameter, the well depth structural design parameter and the pore fluid temperature and pressure parameter of the target stratum;
the second processing unit is used for obtaining a core sample of the target stratum area, determining rock strength parameters and elastic parameters of a certain depth and a horizon through an indoor triaxial mechanical experiment, and determining a stress-strain constitutive relation;
the third processing unit is used for carrying out calibration and correction on the rock mechanics interpretation result and the three-dimensional geologic body model of the logging data in the target stratum region based on the stress-strain constitutive relation in the second processing unit, and describing the initial ground stress state and the geomechanical characteristics of the three-dimensional space of the target stratum;
the fourth processing unit is used for establishing a three-dimensional non-structural geometric grid conforming to the geomechanical and physical characteristics of the stratum based on the initial ground stress state and the geomechanical characteristics in the third processing unit, and determining the space geometric parameters of the well wall stability model;
the fifth processing unit is used for optimizing the three-dimensional space grid subdivision by utilizing the non-structural grid based on the three-dimensional non-structural geometric grid constructed by the fourth processing unit to form an initial three-dimensional geomechanical model;
the sixth processing unit is used for respectively establishing theoretical models for representing the seepage field, the temperature field and the space-time evolution law of the stress field based on the seepage mechanical parameters, the thermodynamic parameters and the rock mechanical parameters of the target stratum, the space geometric parameters in the fourth processing unit and the initial three-dimensional geomechanical model in the fifth processing unit;
the seventh processing unit is used for further establishing a control equation of a heat-flow coupling mechanism, a flow-solid coupling mechanism and a heat-solid coupling mechanism based on a theoretical model of a single physical field space-time evolution rule characterized by the sixth processing unit, so as to realize well wall stability analysis under the conditions of multi-physical field coupling and synergy;
the eighth processing unit is used for forming a multi-physical field coupling partial differential equation set aiming at the stratum based on a theoretical model of a seepage field, a temperature field and a stress field space-time evolution rule in the sixth processing unit and a coupling mechanism equation in the seventh processing unit, performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite element method on the basis, performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite difference method, and further solving the pressure, the stress and the temperature;
the ninth processing unit is used for calculating the dynamic response characteristics of the surrounding rock stress of the well under the density of the drilling fluid in a certain range based on the actual engineering requirements of the target stratum area, analyzing the influence of the temperature, the pressure and the mechanical characteristics of stratum rock on the dynamic response characteristics, determining the degradation area and the range of the mechanical characteristics, and quantitatively analyzing the instability possibility of the well wall;
and the tenth processing unit is used for carrying out parameter sensitivity analysis based on a theoretical model of the seepage field, the temperature field and the stress field space-time evolution rule in the sixth processing unit, respectively carrying out analysis on geological parameters and engineering parameters, determining the influence mode and the influence degree of each geological parameter and engineering parameter on the stability of the well wall, determining the parameters playing a main control role and helping the field of the oil field to carry out the optimization of the drilling parameters.
The invention also provides a computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of the fluid-solid-thermal multi-field coupled borehole wall stability analysis method described above.
The invention also provides a computer device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the steps of the fluid-solid-heat multi-field coupling well wall stability analysis method when executing the computer program.
Due to the adoption of the technical scheme, the invention has the following advantages:
(1) The invention provides a thermal-fluid-solid full-coupling well wall stability analysis flow aiming at high-temperature, high-pressure and high-stress environments of deep ground layers;
(2) The analysis method can overcome the defect that the traditional well wall stability analysis method cannot characterize the thermal strain and the mechanical property evolution under the high-temperature environment;
(3) The method can improve the prediction precision of the mechanical response of the well Zhou Yandan induced by deep stratum drilling and improve the effectiveness of a drilling fluid density window. The field application of the well wall stability analysis method in the invention shows that the well wall stability analysis method optimizes the well drilling parameters.
Drawings
FIG. 1 is a flow chart of a method for analyzing stability of a fluid-solid-thermal multi-field coupled borehole wall in a high temperature and high stress formation environment according to an embodiment of the present invention;
FIG. 2 is a graph of the well surrounding rock shear failure zone prediction provided by this embodiment of the present invention;
fig. 3 is a graph showing the trend of the impact of the pressure of the column of drilling fluid on the stability of the well wall according to this embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are intended to be within the scope of the present disclosure.
As shown in fig. 1, the invention provides a method for analyzing the stability of a fluid-solid-thermal multi-field coupling well wall aiming at a stratum, which comprises the following steps:
1) And (3) defining the geological condition of the target stratum, and collecting the rock mechanical parameters, the well depth structural design parameters and the pore fluid temperature and pressure parameters of the target stratum. The rock mechanical parameters specifically comprise main stress, tensile strength, compressive strength and elastic parameters; the well depth structural design parameters specifically comprise well inclination, azimuth angle and well depth; the pore fluid temperature and pressure parameters specifically comprise formation pressure coefficient, ground temperature gradient, viscosity, formation volume coefficient and the like.
2) And obtaining a core sample of the target stratum region, determining rock strength parameters and elasticity parameters of a certain depth and a horizon through an indoor triaxial mechanical experiment, forming knowledge of spatial distribution of the rock strength and elasticity parameters in the target region, determining a stress-strain constitutive relation, and quantifying a stress and strain evolution rule in the rock deformation process. The indoor triaxial mechanical experiment is an experimental method commonly used by those skilled in the art.
3) Based on the stress-strain constitutive relation in the step 2), calibration and correction are carried out on the rock mechanics interpretation result and the three-dimensional geologic body model of the logging data in the target stratum area, and the initial ground stress state and the geomechanical characteristics of the three-dimensional space of the target stratum are described, so that the precision of the three-dimensional ground stress and the geomechanical model of the deep stratum is improved.
In this step, the interpretation of the logging data rock mechanics is: by using logging data (such as gamma logging, sonic logging, borehole diameter logging, density logging and the like) measured in each oil-gas well, rock elasticity parameters (elastic modulus, poisson ratio) and ground stress (horizontal main stress, vertical main stress and the like) and strength parameters (fracture toughness, tensile strength and the like) of each depth of the oil-gas well can be calculated through a rock mechanics theoretical formula. The elastic parameters, the ground stress and the strength parameters are rock mechanics data, so the process is called rock mechanics interpretation of logging data, and the interpreted rock mechanics parameters are interpretation results.
The three-dimensional geologic body model refers to: the interpretation based on the logging data is in a single well scale (two dimensions), the interpretation of multiple wells in the oil field is summarized, and a three-dimensional model can be formed through a difference method to form a three-dimensional geologic body model.
4) Based on the initial ground stress state and the geomechanical characteristics in the step 3), a three-dimensional non-structural geometric grid conforming to the geomechanical and physical characteristics of the stratum is established, and the space geometric parameters of the well wall stability model are determined.
The three-dimensional non-structural geometric grid specifically refers to a non-uniform-size grid consisting of three-dimensional tetrahedrons; the spatial geometry parameters specifically include a borehole trajectory delineated by a three-dimensional tetrahedron and a deep formation investigation region.
5) And (3) optimizing three-dimensional space grid subdivision by utilizing the non-structural grids based on the three-dimensional non-structural geometric grids constructed in the step (4) to form an initial three-dimensional geomechanical model. The three-dimensional geomechanical model specifically refers to a mathematical model describing the distribution of the earth stress and rock mechanical parameters in the longitudinal and transverse directions in the deep stratum.
6) Respectively establishing theoretical models for representing the seepage field, the temperature field and the stress field space-time evolution law based on the seepage mechanical parameters, the thermodynamic parameters and the rock mechanical parameters of the target stratum, the space geometric parameters in the step 4) and the initial three-dimensional geomechanical model in the step 5); comprising the following control equation:
seepage field control equation:
temperature field control equation:
stress field control equation:
wherein phi is the porosity of surrounding rock of the well wall; ρ i Is pore fluid density; t is time;
is Hamiltonian; u (u) is Is the pore fluid flow rate; q i Flow rate for drilling fluid to the formation; c r Is specific heat; t is the temperature;lambda is the coefficient of thermal conductivity; q h Is a heat source and a heat sink; sigma is the second order stress tensor; wherein the pore fluid flow rate u is By->
Obtaining, wherein k is the porosity of surrounding rock of the well wall; mu (mu) i Is the viscosity of the fluid; p is formation pore pressure; g is gravity acceleration; z is the depth of the deep formation.
7) Based on the theoretical model of the single physical field space-time evolution rule characterized in the step 6), further establishing a thermal-flow coupling, a flow-solid coupling and a thermal-solid coupling mechanism control equation to realize well wall stability analysis under the conditions of multi-physical field coupling and synergy; the method comprises the following steps:
thermal-flow coupling mechanism:
flow-solid coupling mechanism:
thermal-solid coupling mechanism:
ε ij ＝α(T)·(T-T 0 )
wherein, c i Is the specific heat capacity of the fluid; u (u) s Is the rock deformation speed; epsilon ij Is a thermal strain; alpha is the thermal expansion coefficient; t (T) 0 Is the reference temperature.
8) Based on the theoretical model of the seepage field, the temperature field and the stress field space-time evolution law in the step 6) and the coupling mechanism equation in the step 7), a multi-physical field coupling partial differential equation set aiming at stratum is formed, on the basis, the multi-physical field coupling partial differential equation set is spatially dispersed by using a finite element method, and the multi-physical field coupling partial differential equation set is spatially dispersed by using a finite difference method, so that the pressure, the stress and the temperature are obtained.
Fig. 2 is a range of shear failure of the surrounding rock of the well, whereby the risk of induced borehole wall instability of the drilling parameters can be quantitatively determined.
9) Based on the actual engineering requirements of a target stratum area, the dynamic response characteristics (borehole collapse pressure and fracture pressure) of surrounding rock stress of a well under a certain range of drilling fluid density are calculated, the influence of temperature, pressure and stratum rock mechanical characteristics on the dynamic response characteristics is analyzed, the mechanical characteristic degradation area and range are determined, and the possibility of well wall instability is quantitatively analyzed. FIG. 3 is a graph showing the quantitative relationship of drilling fluid column pressure, ground stress non-uniformity, collapse pressure, and fracture pressure. As can be seen from fig. 3, the stronger the ground stress non-uniformity, the narrower the drilling fluid density safety window, which is determined by the collapse pressure and the fracture pressure, the higher the requirements for drilling parameters.
10 Based on the theoretical model of the seepage field, the temperature field and the stress field space-time evolution law in the step 6), carrying out parameter sensitivity analysis, respectively carrying out analysis on geological parameters (formation porosity, permeability, thickness, in-situ stress, formation fluid physical properties and the like) and engineering parameters (borehole size, borehole structure, drilling mud density, drilling time and the like), determining the influence mode and the influence degree of each geological parameter and engineering parameter on the stability of the borehole wall, determining the parameters playing a main control role, and helping the field to carry out the optimization of the drilling parameters.
The invention also provides a device for analyzing the stability of the fluid-solid-thermal multi-field coupling well wall, which comprises the following components:
the first processing unit is used for defining the geological condition of the target stratum and collecting the rock mechanical parameter, the well depth structural design parameter and the pore fluid temperature and pressure parameter of the target stratum;
the second processing unit is used for obtaining a core sample of the target stratum area, determining rock strength parameters and elastic parameters of a certain depth and a horizon through an indoor triaxial mechanical experiment, and determining a stress-strain constitutive relation;
the third processing unit is used for carrying out calibration and correction on the rock mechanics interpretation result and the three-dimensional geologic body model of the logging data in the target stratum region based on the stress-strain constitutive relation in the second processing unit, and describing the initial ground stress state and the geomechanical characteristics of the three-dimensional space of the target stratum;
the fourth processing unit is used for establishing a three-dimensional non-structural geometric grid conforming to the geomechanical and physical characteristics of the stratum based on the initial ground stress state and the geomechanical characteristics in the third processing unit, and determining the space geometric parameters of the well wall stability model;
the fifth processing unit is used for optimizing the three-dimensional space grid subdivision by utilizing the non-structural grid based on the three-dimensional non-structural geometric grid constructed by the fourth processing unit to form an initial three-dimensional geomechanical model;
the sixth processing unit is used for respectively establishing theoretical models for representing the seepage field, the temperature field and the space-time evolution law of the stress field based on the seepage mechanical parameters, the thermodynamic parameters and the rock mechanical parameters of the target stratum, the space geometric parameters in the fourth processing unit and the initial three-dimensional geomechanical model in the fifth processing unit;
the seventh processing unit is used for further establishing a control equation of a heat-flow coupling mechanism, a flow-solid coupling mechanism and a heat-solid coupling mechanism based on a theoretical model of a single physical field space-time evolution rule characterized by the sixth processing unit, so as to realize well wall stability analysis under the conditions of multi-physical field coupling and synergy;
the eighth processing unit is used for forming a multi-physical field coupling partial differential equation set aiming at the stratum based on a theoretical model of a seepage field, a temperature field and a stress field space-time evolution rule in the sixth processing unit and a coupling mechanism equation in the seventh processing unit, performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite element method on the basis, performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite difference method, and further solving the pressure, the stress and the temperature;
the ninth processing unit is used for calculating the dynamic response characteristics of the surrounding rock stress of the well under the density of the drilling fluid in a certain range based on the actual engineering requirements of the target stratum area, analyzing the influence of the temperature, the pressure and the mechanical characteristics of stratum rock on the dynamic response characteristics, determining the degradation area and the range of the mechanical characteristics, and quantitatively analyzing the instability possibility of the well wall;
and the tenth processing unit is used for carrying out parameter sensitivity analysis based on a theoretical model of the seepage field, the temperature field and the stress field space-time evolution rule in the sixth processing unit, respectively carrying out analysis on geological parameters and engineering parameters, determining the influence mode and the influence degree of each geological parameter and engineering parameter on the stability of the well wall, determining the parameters playing a main control role and helping the field of the oil field to carry out the optimization of the drilling parameters.
The safe and efficient exploitation of deep stratum oil and gas resources is one of key ways for relieving the external high dependence of petroleum and natural gas in China, the current flow-solid-thermal multi-field coupling well wall stability analysis and countermeasure of the high-temperature and high-stress oil and gas-containing deep stratum are insufficient, and especially the technical means for well wall stability analysis is lacking in stress response under the environment of the temperature exceeding 100 ℃ which is specific to the deep stratum, the technical difficulties exist in determining and optimizing the density of drilling fluid and drilling parameters, and the drilling safety and the high efficiency of the deep stratum are affected. The invention provides a fluid-solid-thermal multi-field coupling well wall stability analysis method for a high-temperature high-stress stratum aiming at the problems.
The invention also provides a computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of the fluid-solid-thermal multi-field coupled borehole wall stability analysis method described above.
The invention also provides a computer device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the steps of the fluid-solid-heat multi-field coupling well wall stability analysis method when executing the computer program.
The present invention is described in terms of flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments. It will be understood that each flowchart and/or block of the flowchart illustrations and/or block diagrams, and combinations of flowcharts and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (4)
1. A method for analyzing the stability of a fluid-solid-thermal multi-field coupling well wall aiming at a stratum is characterized by comprising the following steps:
1) Defining the geological condition of a target stratum, and collecting rock mechanical parameters, well depth structural design parameters and pore fluid temperature and pressure parameters of the target stratum;
2) Obtaining a core sample of a target stratum area, determining rock strength parameters and elasticity parameters of a certain depth and a horizon through an indoor triaxial mechanical experiment, and determining a stress-strain constitutive relation;
3) Based on the stress-strain constitutive relation in the step 2), calibrating and correcting aiming at the rock mechanics interpretation result and the three-dimensional geologic body model of the logging data in the target stratum region, and describing the initial ground stress state and geomechanical characteristics of the three-dimensional space of the target stratum;
4) Based on the initial ground stress state and the geomechanical characteristics in the step 3), establishing a three-dimensional non-structural geometric grid conforming to the geomechanical and physical characteristics of the stratum, and determining the space geometric parameters of a well wall stability model;
5) Optimizing three-dimensional space grid subdivision by utilizing the non-structural grids based on the three-dimensional non-structural geometric grids constructed in the step 4) to form an initial three-dimensional geomechanical model;
6) Respectively establishing theoretical models for representing the seepage field, the temperature field and the stress field space-time evolution law based on the seepage mechanical parameters, the thermodynamic parameters and the rock mechanical parameters of the target stratum, the space geometric parameters in the step 4) and the initial three-dimensional geomechanical model in the step 5);
7) Based on the theoretical model of the single physical field space-time evolution rule characterized in the step 6), further establishing a thermal-flow coupling, a flow-solid coupling and a thermal-solid coupling mechanism control equation to realize well wall stability analysis under the conditions of multi-physical field coupling and synergy;
8) Forming a multi-physical field coupling partial differential equation set aiming at stratum based on the theoretical model of the seepage field, the temperature field and the stress field space-time evolution law in the step 6) and the coupling mechanism equation in the step 7), performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite element method on the basis, performing space dispersion on the multi-physical field coupling partial differential equation set by using a finite difference method, and further solving pressure, stress and temperature;
9) Based on actual engineering requirements of a target stratum area, calculating dynamic response characteristics of rock stress around a well under a certain range of drilling fluid density, analyzing the influence of temperature, pressure and stratum rock mechanical characteristics on the dynamic response characteristics, determining a mechanical characteristic degradation area and range, and quantitatively analyzing the possibility of well wall instability;
10 Based on the theoretical model of the seepage field, the temperature field and the stress field space-time evolution law in the step 6), carrying out parameter sensitivity analysis, respectively carrying out analysis on geological parameters and engineering parameters, determining the influence mode and the influence degree of each geological parameter and engineering parameter on the stability of the well wall, determining the parameters playing a main control role, and helping the oilfield site to carry out well drilling parameter optimization;
the theoretical model of the space-time evolution law of the seepage field, the temperature field and the stress field in the step 5) comprises the following control equation:
seepage field control equation:
temperature field control equation:
stress field control equation:
wherein phi is the porosity of surrounding rock of the well wall; ρ i Is pore fluid density; t is time;
is Hamiltonian; u (u) is Is the pore fluid flow rate; q i Flow rate for drilling fluid to the formation; c r Is specific heat; t is the temperature; lambda is the coefficient of thermal conductivity; q h Is a heat source and a heat sink; sigma is the second order stress tensor; wherein the pore fluid flow rate u is By->
Find mu i Is the viscosity of the fluid; p is formation pore pressure; g is gravity acceleration; z is the depth of the deep formation;
the control equations of the thermal-flow coupling, the flow-solid coupling and the thermal-solid coupling mechanisms in the step 6) are specifically as follows:
thermal-flow coupling mechanism:
flow-solid coupling mechanism:
thermal-solid coupling mechanism:
ε ij ＝α(T)·(T-T 0 )
wherein, c i Is the specific heat capacity of the fluid; u (u) s Is the rock deformation speed; epsilon ij Is a thermal strain; alpha is the thermal expansion coefficient; t (T) 0 Is the reference temperature.
2. The method of claim 1, wherein the geological parameters in step 10) include formation porosity, permeability, thickness, in situ stress, and formation fluid properties, and the engineering parameters include wellbore size, wellbore structure, drilling mud density, and drilling time.
3. A computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor implements the steps of the fluid-solid-thermal multi-field coupled borehole wall stability analysis method of claim 1 or 2.
4. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor performs the steps of the fluid-solid-thermal multi-field coupled borehole wall stability analysis method of claim 1 or 2 when the computer program is executed.
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