CN109555515A  Formation collapsed pressure determines method and apparatus  Google Patents
Formation collapsed pressure determines method and apparatus Download PDFInfo
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 CN109555515A CN109555515A CN201811167359.2A CN201811167359A CN109555515A CN 109555515 A CN109555515 A CN 109555515A CN 201811167359 A CN201811167359 A CN 201811167359A CN 109555515 A CN109555515 A CN 109555515A
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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
 E21B49/006—Measuring wall stresses in the borehole
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Abstract
The present invention provides a kind of formation collapsed pressure and determines method and apparatus, this method comprises: obtaining the weak facing parameter of formation at target locations and the mechanics parameters of the formation at target locations；The caving pressure computation model of the formation at target locations is established according to the weak facing parameter and the mechanics parameters；The initial input value of the caving pressure computation model is determined according to the weak facing parameter；The initial input value is inputted into the caving pressure computation model and is iterated calculating, obtains the caving pressure value of the formation at target locations.The program fully takes into account influence of the weak facing structure of formation at target locations to rock mass damage rule, accurate caving pressure value can be obtained, the failure law of the rock with plane of weakness structure can really be reacted, be conducive to the density for accurately adjusting drilling fluid in drilling process, reduce layer cavein risk.
Description
Technical field
The present invention relates to petroleum drilling technology fields more particularly to a kind of formation collapsed pressure to determine method and apparatus.
Background technique
Borehole well instability is common problem in Process of Oil Well Drilling, and according to statistics, 90% or more borehole well instability occurs
In mud shale stratum, wherein slit formation mud shale stratum accounts for about 2/3, when boring chance slit formation mud shale stratum, often due to well
Wall unstability generates a large amount of collapsing and breaking, drilling fluid and the serious complicated situation such as frequently misses.The Yumen Oilfield in China western part, bavin
Up to tub, the tectonic movements such as the Junggar Basin, Tarim Basin consumingly band and THE WESTERN SOUTH CHINA SEA Beibuwan Basin and the Bohai Sea
The areas such as oil field, Deep Fractured mud shale stratum encounter serious hole collapse problem when creeping into, return out more collapsing
Chip offfalling causes part wellbore to be forced sidetracking.Once there is borehole well instability, often extend drilling period, causes drilling cost big
Big to increase, therefore, in Process of Oil Well Drilling, Accurate Prediction maintains the density of the drilling fluid of wellbore stability to be particularly important.
Differentiate borehole well instability, it is important to suitable failure criteria is chosen, in the prior art, generally according to the sheet of mud shale
Structure relationship calculates the stress state of wellbore under the influence of different factors, so that it is determined that maintaining the minimum brill of wellbore stability
Well liquid density value namely caving pressure.Currently, using more for Mohr Coulomb's criteria, table in borehole wall stability analysis
It is as follows up to formula:
τ=C+ σ tan φ (1)
Wherein, σ is the direct stress on bad face, unit MPa；τ is shear stress, unit MPa；C is the cohesive strength of rock,
Unit is MPa；φ is the internal friction angle of rock.
Mohr Coulomb's criteria can also be expressed by way of principal stress, expression formula is as follows:
Wherein, σ_{1}For maximum principal stress, unit MPa；σ_{3}For minimum principal stress.
The criterion thinks that the destruction of rock is mainly related with its internal shear stress τ and direct stress σ, when a certain flat in rock
When direct stress σ and shear stress τ on face meet certain functional relation, rock is just destroyed along the plane.
But abovementioned criterion has ignored intermediate principal stress σ_{2}For analyzing the influence of result, and assumes the destruction of rock and only take
Certainly in σ_{1}And σ_{3}, therefore abovementioned criterion is only applicable to analyze complete stratum.And for for example for slit formation mud shale inside in this way
There are for the rock of the planes of weakness structure such as stratification, crack, the destruction along plane of weakness usually occurs for rock, and abovementioned criterion often makes to collapse
The error calculated of pressure is larger, can not really react the failure law of the rock with plane of weakness structure, and then can not
The density for accurately adjusting drilling fluid in drilling process in due course, increases understratum cavein risk.Once drilling fluid is close
Angle value is too low, since stratum has been damaged, even if subsequent raising drilling fluid density value, can not effectively support the borehole wall.
Summary of the invention
The present invention provides a kind of formation collapsed pressure and determines method and apparatus, fully takes into account the weak facing of formation at target locations
Influence of the structure to rock mass damage rule comprehensively considers weak facing parameter and mechanics parameters to determine collapsing for formation at target locations
Calculation of pressure of collapsing model, and further combined with weak facing parameter come determine caving pressure computation model initial input value carry out
Iterative calculation, and then accurate caving pressure value can be obtained, it can really react the rock with plane of weakness structure
Failure law is conducive to the density for accurately adjusting drilling fluid in drilling process, reduces layer cavein risk.
The first aspect of the present invention provides a kind of formation collapsed pressure and determines method, comprising: obtains the rock mass of formation at target locations
The mechanics parameters of plane of weakness parameter and the formation at target locations；It is built according to the weak facing parameter and the mechanics parameters
Found the caving pressure computation model of the formation at target locations；The caving pressure computation model is determined according to the weak facing parameter
Initial input value；The initial input value is inputted into the caving pressure computation model and is iterated calculating, obtains the mesh
Mark the caving pressure value on stratum.
Optionally, described that collapsing for the formation at target locations is established according to the weak facing parameter and the mechanics parameters
Calculation of pressure of collapsing model includes: according to the weak facing parameter and the mechanics parameters using described in the conduct of following formula
Caving pressure computation model:
Wherein:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
σ_{1}For the maximum principal stress of the formation at target locations, unit is MPa；σ_{3}It is single for the minimum principal stress of the formation at target locations
Position is MPa；C_{o}For the plane of weakness cohesive strength of the formation at target locations, unit is MPa；φ is friction in the plane of weakness of the formation at target locations
Angle；A_{1}、B_{1}、A_{2}、B_{2}, α, φ, n, m be determined by experiment according to the weak facing parameter and the mechanics parameters
Constant, wherein n, m are integers.
Optionally, the initial input value packet that the caving pressure computation model is determined according to the weak facing parameter
It includes: the smallest initial drilling fluid density value is determined according to the weak facing parameter；According to the initial drilling fluid density value meter
Calculate the formation at target locations initial maximum principal stress and initial minimum principal stress, obtain the initial input value.
Optionally, described that the initial input value input caving pressure computation model is iterated calculating, it obtains
The caving pressure value of the formation at target locations includes: will be described in the initial maximum principal stress and the initial minimum principal stress input
Caving pressure computation model judges whether the formation at target locations occurs borehole well instability under the initial drilling fluid density value；If
Borehole well instability occurs for the formation at target locations under the initial drilling fluid density value, then increases the initial drilling fluid density value
After preset density value, iteration drilling fluid density value is obtained；Calculate the corresponding formation at target locations of the iteration drilling fluid density value
Iteration maximum principal stress and iteration minimum principal stress, and it is the iteration maximum principal stress and the iteration minimum principal stress is defeated
Enter the caving pressure computation model, to judge whether the formation at target locations occurs the borehole wall under the iteration drilling fluid density value
Unstability, if so, after repeating to increase the iteration drilling fluid density value preset density value to the formation at target locations whether
The step of unstability is judged, until determining final drilling fluid density value when borehole well instability does not occur for the formation at target locations；Root
The caving pressure value of the formation at target locations is determined according to the final drilling fluid density value.
Optionally, further includes: the formation at target locations is carried out according to the mechanics parameters and the caving pressure value
Assessment.
The second aspect of the present invention provides a kind of formation collapsed pressure determining device, comprising: module is obtained, for obtaining mesh
Mark the weak facing parameter on stratum and the mechanics parameters of the formation at target locations；Module is established, for weak according to the rock mass
Face parameter and the mechanics parameters establish the caving pressure computation model of the formation at target locations；First computing module, is used for
The initial input value of the caving pressure computation model is determined according to the weak facing parameter；Second computing module, being used for will
The initial input value inputs the caving pressure computation model and is iterated calculating, obtains the caving pressure of the formation at target locations
Value.
Optionally, the module of establishing is specifically used for: being adopted according to the weak facing parameter and the mechanics parameters
Use following formula as the caving pressure computation model:
Wherein:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
σ_{1}For the maximum principal stress of the formation at target locations, unit is MPa；σ_{3}It is single for the minimum principal stress of the formation at target locations
Position is MPa；C_{o}For the plane of weakness cohesive strength of the formation at target locations, unit is MPa；φ is friction in the plane of weakness of the formation at target locations
Angle；A_{1}、B_{1}、A_{2}、B_{2}, α, φ, n, m be determined by experiment according to the weak facing parameter and the mechanics parameters
Constant, wherein n, m are integers.
Optionally, first computing module is specifically used for: determining the smallest initial brill according to the weak facing parameter
Well liquid density value；The initial maximum principal stress and initially minimum of the formation at target locations are calculated according to the initial drilling fluid density value
Principal stress obtains the initial input value.
Optionally, second computing module is specifically used for: by the initial maximum principal stress and the initial minimum master
Stress inputs the caving pressure computation model, judges whether the formation at target locations occurs under the initial drilling fluid density value
Borehole well instability；If borehole well instability occurs for the formation at target locations under the initial drilling fluid density value, by the initial drilling well
After liquid density value increases preset density value, iteration drilling fluid density value is obtained；It is corresponding to calculate the iteration drilling fluid density value
The iteration maximum principal stress and iteration minimum principal stress of the formation at target locations, and by the iteration maximum principal stress and the iteration
Minimum principal stress inputs the caving pressure computation model, to judge the formation at target locations under the iteration drilling fluid density value
Whether borehole well instability is occurred, if so, to described after repeating to increase the iteration drilling fluid density value preset density value
Formation at target locations the step of whether unstability is judged, until determining final drilling well when borehole well instability does not occur for the formation at target locations
Liquid density value；The caving pressure value of the formation at target locations is determined according to the final drilling fluid density value.
Optionally, further includes: evaluation module is used for according to the mechanics parameters and the caving pressure value to described
Formation at target locations is assessed.
Formation collapsed pressure provided by the invention determines method and apparatus, passes through the weak facing parameter according to formation at target locations
The caving pressure computation model of the formation at target locations is established with mechanics parameters；And according to the weak facing parameter of formation at target locations
Determine the initial input value of the caving pressure computation model；Later by initial input value input the caving pressure computation model into
Row iteration calculates, and the caving pressure value of formation at target locations can be obtained.Compared with prior art, the rock of formation at target locations is fully taken into account
Influence of the weak face structure to rock mass damage rule, comprehensively considers weak facing parameter and mechanics parameters with determining target
The caving pressure computation model of layer, and determine further combined with weak facing parameter the initial input of caving pressure computation model
Value is iterated calculating, and then can obtain accurate caving pressure value, can really react with plane of weakness structure
The failure law of rock is conducive to the density for accurately adjusting drilling fluid in drilling process, reduces layer cavein risk.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is this hair
Bright some embodiments for those of ordinary skill in the art without any creative labor, can be with
It obtains other drawings based on these drawings.
Fig. 1 determines the flow chart of method for the formation collapsed pressure shown in an exemplary embodiment of the invention；
Fig. 2A determines the flow chart of method for the formation collapsed pressure shown in another exemplary embodiment of the present invention；
Fig. 2 B and Fig. 2 C are the Rock strength testing result and plane of weakness criterion fitting song in Fig. 2A shown in exemplary embodiment
Face figure；
Fig. 3 A to Fig. 3 C is the cloud atlas of caving pressure under different crustal stress in Fig. 2A shown in exemplary embodiment；
Fig. 3 D to Fig. 3 F is that the formation anisotropy in Fig. 2A shown in exemplary embodiment influences relational graph to caving pressure；
Fig. 3 G determines the flow chart of method for the formation collapsed pressure shown in another exemplary embodiment of the present invention；
Fig. 4 is the structure chart of the formation collapsed pressure determining device shown in an exemplary embodiment of the invention；
Fig. 5 is the structure chart of the formation collapsed pressure determining device shown in another exemplary embodiment of the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those skilled in the art are not having
Every other embodiment obtained under the premise of creative work is made, shall fall within the protection scope of the present invention.
Fig. 1 determines the flow chart of method for the formation collapsed pressure shown in an exemplary embodiment of the invention.
As shown in Figure 1, the executing subject of the present embodiment is formation collapsed pressure determining device, which is determined
Device can integrate in the terminal, which can be computer etc..Then the present embodiment provides a kind of formation collapsed pressure determination sides
Method, this method comprises the following steps:
Step 101: obtaining the weak facing parameter of formation at target locations and the mechanics parameters of formation at target locations.
Wherein, formation at target locations is stratum to be studied determine according to actual needs, which can have plane of weakness
Structure, such as Fractured mud shale stratum.Weak facing parameter is to characterize the parameter of the plane of weakness structure of the formation at target locations.Mechanics is special
Property parameter be characterize the formation at target locations mechanical characteristic parameter, such as crustal stress, hole angle, azimuth, formation pore pressure,
The parameters such as elastic model, Poisson's ratio.For the formation at target locations with plane of weakness structure, which also may include target
The mechanics parameters of the plane of weakness occurrence on stratum.
In this step, the caving pressure value for determining formation at target locations in order to be more accurate first has to obtain formation at target locations
Weak facing parameter and mechanics parameters.Specifically, geophysical logging data and drilling and coring delivery description be can use, obtained
Plane of weakness occurrence and its mechanical characteristic of formation at target locations are taken, that is, obtains the weak facing parameter and mechanics parameters of formation at target locations.
In practical applications, geophysical log is referred to as logged well, and is benefit during exploring and exploiting petroleum, coal and metal ore
With the physical parameter of various apparatus measures formation downholes and the technology status of well, recorded data is analyzed, carries out geology and work
Research in terms of journey.Mainly there are electrical log, radioactive logging, acoustic logging and stratum to incline by the physical basis of logging method
Angle well logging etc..In petroleumgas fiedl well logging, welllog information is mainly used for Strata Comparison, divides oil, gas and water layer；Determine reservoir
The important parameters such as porosity, oil saturation, permeability；In petroleumgas fiedl development process, research oil, the dynamic of gas and water and well
Situation, for work out development plan foundation is provided；Using well logging and geology, physical prospecting, development data, the synthesis of areal geology is carried out
Research and reservoir description.Drilling and coring delivery refers to grasp subsurface geology situation, directly obtains true and reliable subterranean strata
Relevant information, in drilling process with coring tool from underground take out big rock sample (rock core) operation.Therefore, can pass through
The weak facing parameter and mechanics parameters of above method acquisition formation at target locations.Other feasible methods can certainly be passed through
Parameter acquisition is carried out, the mode that the application obtains parameter is without limitation.
Step 102: the caving pressure computation model of formation at target locations is established according to weak facing parameter and mechanics parameters.
In this step, influence of the weak facing structure of formation at target locations to rock mass damage rule is fully taken into account, it is comprehensive
Weak facing parameter and mechanics parameters are considered to determine the caving pressure computation model of formation at target locations.It specifically, can be by
Several rock cores are drilled through along different directions according to actual requirement, carry out rock mechanics intensity experiment, obtains and considers that stratum dynamics characteristic is each
The changing rule of anisotropy, by the calculating parameter of the related plane of weakness failure criteria formula of laboratory experiment result and data fitting acquisition,
And then determine the caving pressure computation model of formation at target locations.
Step 103: the initial input value of caving pressure computation model is determined according to weak facing parameter.
In this step, caving pressure computation model is used to determine the caving pressure of formation at target locations, and determines caving pressure
Need to judge borehole wall unstability under which kind of state, it is important to suitable failure criteria is chosen, then according to this structure of formation at target locations
Relationship calculates the stress state of wellbore under the influence of different factors.In the present embodiment, since weak facing parameter can shadow
Ring the failure law of formation at target locations, therefore the initial input by determining caving pressure computation model according to weak facing parameter
Value, can be further improved the calculated result of caving pressure value.
Step 104: initial input value input caving pressure computation model being iterated calculating, obtains collapsing for formation at target locations
It collapses pressure value.
In this step, after initial input value being determined according to weak facing parameter, initial input value can be inputted and is collapsed
Calculation of pressure of collapsing model is iterated calculating, is calculated using the method for iterative numerical, so as to find out differently stress condition
Under caving pressure value.Due to being difficult to acquire the analytic solutions of the caving pressure on stratum, it is therefore desirable to using the method iteration of numerical value
Calculating can obtain optimal solution, therefore can obtain the practical caving pressure value closest to formation at target locations.It thus can be more true
Real reaction has the failure law of the rock of plane of weakness structure, is conducive to the density for accurately adjusting drilling fluid in drilling process,
Reduce layer cavein risk.
Formation collapsed pressure provided by the invention determines method, passes through the weak facing parameter and mechanics according to formation at target locations
Characterisitic parameter establishes the caving pressure computation model of formation at target locations；And the collapsing is determined according to the weak facing parameter of formation at target locations
The initial input value of calculation of pressure model；Initial input value input caving pressure computation model is iterated calculating later, i.e.,
The caving pressure value of formation at target locations can be obtained.Compared with prior art, the weak facing structure pair of formation at target locations is fully taken into account
The influence of rock mass damage rule comprehensively considers weak facing parameter and mechanics parameters to determine the caving pressure of formation at target locations
Computation model, and determine that the initial input value of caving pressure computation model is iterated meter further combined with weak facing parameter
It calculates, and then accurate caving pressure value can be obtained, can really react the destruction rule of the rock with plane of weakness structure
Rule is conducive to the density for accurately adjusting drilling fluid in drilling process, reduces layer cavein risk.
Fig. 2A determines the flow chart of method for the formation collapsed pressure shown in another exemplary embodiment of the present invention.
Fig. 2 B and Fig. 2 C are the Rock strength testing result and plane of weakness criterion fitting song in Fig. 2A shown in exemplary embodiment
Face figure.
Fig. 3 A to Fig. 3 C is the cloud atlas of caving pressure under different crustal stress in Fig. 2A shown in exemplary embodiment.
Fig. 3 D to Fig. 3 F is that the formation anisotropy in Fig. 2A shown in exemplary embodiment influences relational graph to caving pressure.
As shown in Figure 2 A, the present embodiment provides a kind of formation collapsed pressures to determine method, is in an exemplary reality of the invention
It applies on the basis of the formation collapsed pressure exemplified determines method, further comprises the caving pressure computation model for establishing formation at target locations
Specific steps, determine caving pressure computation model initial input value specific steps, by initial input value input collapse pressure
Power computation model is iterated calculating, obtains the specific steps of the caving pressure value of formation at target locations, and join according to mechanical characteristic
The step of several and caving pressure value assesses formation at target locations etc..
In order to more intuitively specifically describe the method flow of the present embodiment, come below with reference to a specific embodiment detailed
Thin description this embodiment scheme.Then this method comprises the following steps:
Step 201: obtaining the weak facing parameter of formation at target locations and the mechanics parameters of formation at target locations.
Wherein, formation at target locations is stratum to be studied determine according to actual needs, which can have plane of weakness
Structure, such as Fractured mud shale stratum.Weak facing parameter is to characterize the parameter of the plane of weakness structure of the formation at target locations.Mechanics is special
Property parameter be characterize the formation at target locations mechanical characteristic parameter, such as crustal stress, hole angle, azimuth, formation pore pressure,
The parameters such as elastic model, Poisson's ratio.For the formation at target locations with plane of weakness structure, which also may include target
The mechanics parameters of the plane of weakness occurrence on stratum.
In this step, the caving pressure value for determining formation at target locations in order to be more accurate first has to obtain formation at target locations
Weak facing parameter and mechanics parameters.Specifically, geophysical logging data and drilling and coring delivery description be can use, obtained
Plane of weakness occurrence and its mechanical characteristic of formation at target locations are taken, that is, obtains the weak facing parameter and mechanics parameters of formation at target locations.
In practical applications, geophysical log is referred to as logged well, and is benefit during exploring and exploiting petroleum, coal and metal ore
With the physical parameter of various apparatus measures formation downholes and the technology status of well, recorded data is analyzed, carries out geology and work
Research in terms of journey.Mainly there are electrical log, radioactive logging, acoustic logging and stratum to incline by the physical basis of logging method
Angle well logging etc..Drilling and coring delivery refers to grasp subsurface geology situation, directly obtains the related of true and reliable subterranean strata
Data takes out the operation of big rock sample (rock core) in drilling process with coring tool from underground.Therefore, abovementioned side can be passed through
The weak facing parameter and mechanics parameters of method acquisition formation at target locations.It can certainly be joined by other feasible methods
Number obtains, and the mode that the application obtains parameter is without limitation.It is available for using Bohai Sea oil field as formation at target locations
Its relevant weak facing parameter and mechanics parameters are as shown in table 1:
1 Fractured mud shale stratum calculating parameter table of table
Step 202: mould is calculated as caving pressure using following formula according to weak facing parameter and mechanics parameters
Type:
Wherein:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
σ_{1}For the maximum principal stress of formation at target locations, unit is MPa；σ_{3}For the minimum principal stress of formation at target locations, unit is MPa；
C_{o}For the plane of weakness cohesive strength of formation at target locations, unit is MPa；φ is the plane of weakness internal friction angle of formation at target locations；A_{1}、B_{1}、A_{2}、B_{2}、α、φ、
N, m is according to weak facing parameter and mechanics parameters constant determined by experiment, and wherein n, m are integers.
In this step, it is Fractured mud shale stratum for formation at target locations, can chooses under different Anisotropy Mechanisms
The failure criteria on single weak plane stratum, expression formula are as follows:
(1) in formula, c_{o}(β), φ (β) indicate cohesive strength and internal friction angle is principal stress σ_{1}The letter of angle β between plane of weakness
Number, concrete form need to be determined by test.
The expression formula of the principal stress form of above formula (1) is as follows:
(2) formula is exactly the caving pressure computation model chosen in the present embodiment, in (2) formula:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
Wherein, A_{1}、B_{1}、A_{2}、B_{2}, α, φ be the determining constant of test, n, m are that fixed integer is obtained by test.σ_{1}For target
The maximum principal stress on stratum, unit are MPa；σ_{3}For the minimum principal stress of formation at target locations, unit is MPa；C_{o}For the weak of formation at target locations
Face cohesive strength, unit are MPa；φ is the plane of weakness internal friction angle of formation at target locations；The present embodiment can regard Fractured mud shale as
Transverse isotropy stratum considers that amendment MC criterion has 12 parameters, determines that the value of these parameters is relatively difficult, to simplify meter
Calculate and facilitate the value for determining each parameter, it can be assumed that internal friction angle is constant.Under the conditions of determining different confining pressures by laboratory test
The breakdown strength on stratum, and then determine the value of Model Parameter.
Stress in abovementioned (2) formula is that effective stress can with first acquiring target before the caving pressure for calculating stratum
The effective stress of layer.Such as can be theoretical according to Biot effective stress, obtain effective stress suffered by formation at target locations rock and total
Relationship is shown in formula (3) between stress:
σ_{ij}=σ '_{ij}+αP_{p}δ_{ij}(3)
Wherein σ_{ij}' it is effective stress suffered by formation rock, MPa；α is effective stress coefficient；P_{p}For the fluid column in pit shaft
Pressure, MPa；δ_{ij}It is kronecker delta.The effective stress of formation at target locations can be acquired by (3) formula.
In concrete application scene, it can drill through the rock core at the testing site of formation at target locations according to actual requirement and carry out power
Experiment is learned, is drilled through between rock core axis and bed plane normal by given angle.Joined using MTS testing machine measurement mechanical characteristic
Number.As shown in Figure 2 B, for example core diameter and length are respectively 25mm and 50mm, the angle degree difference of axial stress and bed plane
It is 0 °, 15 °, 30 °, 45 °, 60 °, 75 °, 90 °.It can be carried out curve fitting, be obtained in judgment criterion according to amendment MC criterion
Calculating parameter.Breakdown strength experimental data is returned according to formula (2), the formation at target locations can be obtained uses amendment M
The failure by shear criterion of strength that C criterion indicates, and regression parameter is obtained, it is the experimental data according to testing site as shown in Figure 2 C
Obtained fitting surface.For the Bohai Sea middeep strata rock shown in the table 1, then A is obtained_{1}=18.2, A_{2}=15.8, B_{1}=
9.88 B_{2}=7.94, α=47 °, φ=33.79 °, n=m=4.Parameter in failure criteria is based on rock indoor test knot
Fruit, result fitting degree are higher.
Step 203: the smallest initial drilling fluid density value is determined according to weak facing parameter.
In this step, according to the weak facing parameter of formation at target locations, such as the crustal stress according to formation at target locations, hole deviation
Angle, azimuth, formation pore pressure, elastic model, Poisson's ratio etc. determine the smallest initial drilling fluid density value.Herein, initially
Drilling fluid density value can be carried out according to the actual situation it is assumed that guaranteeing that the initial drilling fluid density value is that the wing of nose is relatively small
Value, to guarantee under initial drilling fluid density value to try not that borehole well instability occurs.
Step 204: the initial maximum principal stress that formation at target locations is calculated according to initial drilling fluid density value and initially minimum master
Stress obtains initial input value.
In this step, the distribution that wellbore stress state can be calculated according to initial drilling fluid density value, by answering
Power conversion calculates the stress state of plane of weakness, it can the initial maximum principal stress and initial minimum master that formation at target locations is calculated are answered
Power, the initial maximum principal stress and initial minimum principal stress are exactly the initial input value of caving pressure computation model.
Step 205: initial maximum principal stress and initial minimum principal stress being inputted into caving pressure computation model, judged first
Whether formation at target locations occurs borehole well instability under beginning drilling fluid density value.If so, thening follow the steps 206.
In this step, using formula (2) as caving pressure computation model, that is to say, that when the maximum master of formation at target locations answers
Power and minimum principal stress meet the relationship of formula (2), will collapse.Then initial maximum principal stress and initial minimum master are answered
After power inputs caving pressure computation model, whether can meet formula according to the initial maximum principal stress and initial minimum principal stress
(2), judge whether formation at target locations occurs borehole well instability under initial drilling fluid density value.
Step 206: if borehole well instability occurs for formation at target locations under initial drilling fluid density value, by initial drilling fluid density
After value increases preset density value, iteration drilling fluid density value is obtained.
In this step, if borehole well instability occurs for formation at target locations under initial drilling fluid density value, illustrate initial drilling fluid
Density value is too small, is not able to satisfy safety drilling condition, then after initial drilling fluid density value being increased preset density value, obtains iteration
Drilling fluid density value.Herein, preset density value can be depending on specific actual scene, to guarantee final computational accuracy for original
Then.
Step 207: iteration maximum principal stress and the iteration for calculating the corresponding formation at target locations of iteration drilling fluid density value are minimum
Principal stress, and iteration maximum principal stress and iteration minimum principal stress are inputted into caving pressure computation model, to judge to bore in iteration
Whether formation at target locations occurs borehole well instability under well liquid density value, if so, repeating to preset iteration drilling fluid density value increase close
The step of whether unstability judges to formation at target locations after angle value, until determining final when borehole well instability does not occur for formation at target locations
Drilling fluid density value.
In this step, iteration drilling fluid density value is obtained in step 206, then it is corresponding to calculate iteration drilling fluid density value
The iteration maximum principal stress and iteration minimum principal stress of formation at target locations, and iteration maximum principal stress and iteration minimum principal stress is defeated
Enter caving pressure computation model, and is determined according to whether iteration maximum principal stress and iteration minimum principal stress meet formula (2)
Whether formation at target locations occurs borehole well instability under iteration drilling fluid density value, if it is satisfied, then borehole well instability can occur for explanation, then
It repeats the step of whether unstability judges to formation at target locations after iteration drilling fluid density value increase preset density value, i.e. basis
Drilling fluid density value and preset density value use formula (2) to be iterated calculating, until determining that borehole wall mistake does not occur for formation at target locations
Final drilling fluid density value when steady.Then the final drilling fluid density value just may be regarded as maintaining the lower limit value of wellbore stability.
Step 208: the caving pressure value of formation at target locations is determined according to final drilling fluid density value.
In this step, the drilling fluid density lower limit value for maintaining wellbore stability, i.e., final drilling fluid have been determined in step 207
Density value then can obtain the caving pressure value of formation at target locations according to the relationship of drilling fluid density and caving pressure.
Step 209: formation at target locations being assessed according to mechanics parameters and caving pressure value.
It in this step, can be according to mechanics parameters and collapsing after the caving pressure value of formation at target locations has been determined
Pressure value assesses formation at target locations.For example considering formation anisotropy, quantitative assessment elasticity modulus, Poisson's ratio are pressed collapsing
Power influences, and establishes well track and caving pressure wind distribution relation cloud atlas under differently stress condition；Determine stratum respectively to different
Property (elasticity modulus, Poisson's ratio) on caving pressure influence be quantitatively evaluated figure (as shown in Fig. 3 D to Fig. 3 F).And collapsing can be drawn
Pressure with hole deviation, the collapsing cloud atlas of Orientation differences, as shown in Fig. 3 A to Fig. 3 C.
Specifically, Fig. 3 G determines the process of method for the formation collapsed pressure shown in another exemplary embodiment of the present invention
Figure.As shown in Figure 3 G, for calculating the caving pressure of Fractured mud shale stratum, the formation collapsed pressure of the present embodiment is determined
Method may include steps of:
Step 301: being described using geophysical log, obtain plane of weakness occurrence and its mechanical characteristic on stratum.
Step 302: drilling through several rock cores along different directions as requested, carry out rock mechanics intensity experiment, obtain and consider
The changing rule of stratum dynamics intensity anisotropy obtains plane of weakness failure criteria formula by laboratory experiment result and data fitting
(2) calculating parameter；
Step 303: obtaining crustal stress, hole angle, azimuth, formation pore pressure, elastic model, Poisson's ratio.
Step 304: assuming initially that the drilling fluid density initial value an of very little(i.e. initial drilling fluid density value).
Step 305: according to drilling fluid density initial valueThe distribution for calculating wellbore stress state is turned by stress
Change the stress state for calculating plane of weakness.
Step 306: being verified using failure criteria, that is, formula (4), whether stratum occurs failure by shear at this time, i.e., occur
It collapses.
Step 307: if stratum can collapse, using formulaThe drilling fluid density that will assume
Initial valueIncrease the small amount Δ P that can satisfy computational accuracy, obtains iteration drilling fluid density value P_{w}, calculate wellbore
Around effective stress, and go to step 305；Wherein, if n is the number of iterations, n is positive integer more than or equal to 1, then the
The drilling fluid density value of n times iterationIf stratum, can be drilling well at this time there is no collapsing
Liquid density value is regarded as maintaining the lower limit of wellbore stability, i.e. formation collapsed pressure value, calculating terminates.
Formation collapsed pressure provided in this embodiment determines method, by considering that it is quasi that formation anisotropy chooses formation damage
Then, and then according to weak facing parameter and mechanics parameters the caving pressure computation model for establishing formation at target locations, for crack,
The stratum of the planes of weakness such as stratification, joint development, can accurately calculate caving pressure value from terms of mechanics, using plane of weakness criterion of strength and
Stratum is quantitatively evaluated respectively to different with the changing rule of well track in the method analysis Fractured mud shale that laboratory test combines
Influence degree of the property to caving pressure.And can draw caving pressure with hole deviation, the collapsing cloud atlas of Orientation differences, with the prior art
It compares, avoids in existing method since the caving pressure calculated under different well tracks can underestimate the collapsing of special formation
The case where pressure, and caused by borehole well instability phenomenon.It can fully consider that the planes of weakness such as Fractured mud shale crack, microcrack are developed
Feature is quantitatively evaluated anisotropy to the influence degree of caving pressure, overcomes the shortcomings of traditional computing model, improves prediction essence
Degree.Scene adjustment drilling fluid density value can be effectively instructed, realizes safe and efficient drilling well.
Fig. 4 is the structure chart of the formation collapsed pressure determining device shown in an exemplary embodiment of the invention.
As shown in figure 4, the present embodiment provides a kind of formation collapsed pressure determining device, the formation collapsed pressure determining device
It can integrate in the terminal, which can be computer etc., which includes: to obtain module 401, establish the meter of module 402, first
Calculate module 403 and the second computing module 404.
Wherein, module 401 is obtained, for obtaining the weak facing parameter of formation at target locations and the mechanical characteristic ginseng of formation at target locations
Number；
Module 402 is established, for establishing the caving pressure of formation at target locations according to weak facing parameter and mechanics parameters
Computation model；
First computing module 403, for determining the initial input value of caving pressure computation model according to weak facing parameter；
Second computing module 404 is obtained for initial input value input caving pressure computation model to be iterated calculating
The caving pressure value of formation at target locations.
The detailed content of abovementioned modules is referring to the description in the corresponding embodiment of abovementioned Fig. 1.
Fig. 5 is the structure chart of the formation collapsed pressure determining device shown in another exemplary embodiment of the present invention.
As shown in figure 5, formation collapsed pressure determining device provided in this embodiment is shown in one as shown in Figure 4 of the invention
On the basis of example property implements the formation collapsed pressure determining device exemplified, further, further comprise: evaluation module 405.Its
In:
Optionally, it establishes module 402 to be specifically used for: according to weak facing parameter and mechanics parameters using following formula
As caving pressure computation model:
Wherein:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
σ_{1}For the maximum principal stress of formation at target locations, unit is MPa；σ_{3}For the minimum principal stress of formation at target locations, unit is MPa；
C_{o}For the plane of weakness cohesive strength of formation at target locations, unit is MPa；φ is the plane of weakness internal friction angle of formation at target locations；A_{1}、B_{1}、A_{2}、B_{2}、α、φ、
N, m is according to weak facing parameter and mechanics parameters constant determined by experiment, and wherein n, m are integers.
Optionally, the first computing module 403 is specifically used for: determining that the smallest initial drilling fluid is close according to weak facing parameter
Angle value；According to the initial maximum principal stress of initial drilling fluid density value calculating formation at target locations and initial minimum principal stress, obtain just
Beginning input value.
Optionally, the second computing module 404 is specifically used for: initial maximum principal stress and the input of initial minimum principal stress are collapsed
Calculation of pressure of collapsing model judges whether formation at target locations occurs borehole well instability under initial drilling fluid density value；If in initial drilling well
Borehole well instability occurs for formation at target locations under liquid density value, then after initial drilling fluid density value being increased preset density value, obtains iteration
Drilling fluid density value；The iteration maximum principal stress and iteration minimum master for calculating the corresponding formation at target locations of iteration drilling fluid density value are answered
Power, and iteration maximum principal stress and iteration minimum principal stress are inputted into caving pressure computation model, to judge in iteration drilling fluid
Whether formation at target locations occurs borehole well instability under density value, if so, repeating iteration drilling fluid density value increasing preset density value
The step of whether unstability judges to formation at target locations afterwards, until determining final drilling well when borehole well instability does not occur for formation at target locations
Liquid density value；The caving pressure value of formation at target locations is determined according to final drilling fluid density value.
Optionally, further includes: evaluation module 405 is used for according to mechanics parameters and caving pressure value to formation at target locations
It is assessed.
The detailed content of abovementioned modules is referring in abovementioned Fig. 2A to Fig. 2 C and the corresponding embodiment of Fig. 3 A to Fig. 3 G
Description.
Although being described in conjunction with the accompanying the embodiment of the present invention, those skilled in the art can not depart from the present invention
Spirit and scope in the case where various modifications and variations can be made, such modifications and variations are each fallen within by appended claims institute
Within the scope of restriction.
Claims (10)
1. a kind of formation collapsed pressure determines method characterized by comprising
Obtain the weak facing parameter of formation at target locations and the mechanics parameters of the formation at target locations；
The caving pressure computation model of the formation at target locations is established according to the weak facing parameter and the mechanics parameters；
The initial input value of the caving pressure computation model is determined according to the weak facing parameter；
The initial input value is inputted into the caving pressure computation model and is iterated calculating, obtains collapsing for the formation at target locations
It collapses pressure value.
2. the method according to claim 1, wherein described special according to the weak facing parameter and the mechanics
The caving pressure computation model that property parameter establishes the formation at target locations includes:
Mould is calculated as the caving pressure using following formula according to the weak facing parameter and the mechanics parameters
Type:
Wherein:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
σ_{1}For the maximum principal stress of the formation at target locations, unit is MPa；σ_{3}For the minimum principal stress of the formation at target locations, unit is
MPa；C_{o}For the plane of weakness cohesive strength of the formation at target locations, unit is MPa；φ is the plane of weakness internal friction angle of the formation at target locations；A_{1}、
B_{1}、A_{2}、B_{2}, α, φ, n, m be according to the weak facing parameter and mechanics parameters constant determined by experiment,
Middle n, m are integers.
3. method according to claim 1 or 2, which is characterized in that described according to weak facing parameter determination
The initial input value of caving pressure computation model includes:
The smallest initial drilling fluid density value is determined according to the weak facing parameter；
According to the initial drilling fluid density value calculate the formation at target locations initial maximum principal stress and initial minimum principal stress,
Obtain the initial input value.
4. according to the method described in claim 3, it is characterized in that, described input the caving pressure for the initial input value
Computation model is iterated calculating, and the caving pressure value for obtaining the formation at target locations includes:
The initial maximum principal stress and the initial minimum principal stress are inputted into the caving pressure computation model, judged in institute
State whether the formation at target locations under initial drilling fluid density value occurs borehole well instability；
If borehole well instability occurs for the formation at target locations under the initial drilling fluid density value, by the initial drilling fluid density
After value increases preset density value, iteration drilling fluid density value is obtained；
The iteration maximum principal stress and iteration minimum master for calculating the corresponding formation at target locations of the iteration drilling fluid density value are answered
Power, and the iteration maximum principal stress and the iteration minimum principal stress are inputted into the caving pressure computation model, with judgement
Whether the formation at target locations occurs borehole well instability under the iteration drilling fluid density value, if so, repeating to bore the iteration
The step of whether unstability judges to the formation at target locations after the well liquid density value increase preset density value, until determining institute
State final drilling fluid density value when borehole well instability does not occur for formation at target locations；
The caving pressure value of the formation at target locations is determined according to the final drilling fluid density value.
5. the method according to claim 1, wherein further include:
The formation at target locations is assessed according to the mechanics parameters and the caving pressure value.
6. a kind of formation collapsed pressure determining device characterized by comprising
Module is obtained, for obtaining the weak facing parameter of formation at target locations and the mechanics parameters of the formation at target locations；
Module is established, for establishing the collapsing of the formation at target locations according to the weak facing parameter and the mechanics parameters
Calculation of pressure model；
First computing module, for determining the initial input of the caving pressure computation model according to the weak facing parameter
Value；
Second computing module is iterated calculating for the initial input value to be inputted the caving pressure computation model, obtains
To the caving pressure value of the formation at target locations.
7. device according to claim 6, which is characterized in that the module of establishing is specifically used for:
Mould is calculated as the caving pressure using following formula according to the weak facing parameter and the mechanics parameters
Type:
Wherein:
c_{o}=A_{1}B_{1}[cos 2(αβ)]^{n}, 0 °≤β≤α
c_{o}=A_{2}B_{2}[cos 2(αβ)]^{n}, α < β≤90 °
σ_{1}For the maximum principal stress of the formation at target locations, unit is MPa；σ_{3}For the minimum principal stress of the formation at target locations, unit is
MPa；C_{o}For the plane of weakness cohesive strength of the formation at target locations, unit is MPa；φ is the plane of weakness internal friction angle of the formation at target locations；A_{1}、
B_{1}、A_{2}、B_{2}, α, φ, n, m be according to the weak facing parameter and mechanics parameters constant determined by experiment,
Middle n, m are integers.
8. device according to claim 6 or 7, which is characterized in that first computing module is specifically used for:
The smallest initial drilling fluid density value is determined according to the weak facing parameter；
According to the initial drilling fluid density value calculate the formation at target locations initial maximum principal stress and initial minimum principal stress,
Obtain the initial input value.
9. device according to claim 8, which is characterized in that second computing module is specifically used for:
The initial maximum principal stress and the initial minimum principal stress are inputted into the caving pressure computation model, judged in institute
State whether the formation at target locations under initial drilling fluid density value occurs borehole well instability；
If borehole well instability occurs for the formation at target locations under the initial drilling fluid density value, by the initial drilling fluid density
After value increases preset density value, iteration drilling fluid density value is obtained；
The iteration maximum principal stress and iteration minimum master for calculating the corresponding formation at target locations of the iteration drilling fluid density value are answered
Power, and the iteration maximum principal stress and the iteration minimum principal stress are inputted into the caving pressure computation model, with judgement
Whether the formation at target locations occurs borehole well instability under the iteration drilling fluid density value, if so, repeating to bore the iteration
The step of whether unstability judges to the formation at target locations after the well liquid density value increase preset density value, until determining institute
State final drilling fluid density value when borehole well instability does not occur for formation at target locations；
The caving pressure value of the formation at target locations is determined according to the final drilling fluid density value.
10. device according to claim 6, which is characterized in that further include:
Evaluation module, for being assessed according to the mechanics parameters and the caving pressure value the formation at target locations.
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