CN104732064A - Oil base drilling fluid parameter design method - Google Patents
Oil base drilling fluid parameter design method Download PDFInfo
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- CN104732064A CN104732064A CN201510077222.8A CN201510077222A CN104732064A CN 104732064 A CN104732064 A CN 104732064A CN 201510077222 A CN201510077222 A CN 201510077222A CN 104732064 A CN104732064 A CN 104732064A
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Abstract
The invention discloses an oil base drilling fluid parameter design method. The oil base drilling fluid parameter design method sequentially includes the following steps: physical properties and structure properties of stratum rock are tested though tests; according to the physical properties and the structure properties of the stratum rock, pore structures of typical mineral and the stratum rock are built, a combined characterization model of oil base drilling fluid parameters to wettability of the stratum rock and an oil base drilling fluid system is built, and a relational graph between the oil base drilling fluid parameters and the wettability is drawn; a well wall stable fixed mechanics model of the stratum rock and the oil base drilling fluid system under the wettability condition is built, and a relational graph between the oil base drilling fluid parameters and the well wall stability is drawn; according to the relational graph between the oil base drilling fluid parameters and the well wall stability, the oil base drilling fluid parameters are determined. According to the oil base drilling fluid parameter design method, a window of the designed oil base drilling fluid parameters is accurate and reachable, the effect of the oil base drilling fluid on keeping the well wall stability can be evaluated in a quantitative mode, underground complex conditions are prevented, and the cost of the oil base drilling fluid is reasonably controlled.
Description
Technical field
The invention belongs to oil/gas drilling field of engineering technology, relate to the method for designing of drilling fluid system, particularly relate to a kind of method for designing of oil base drilling fluid parameter.
Background technology
In recent years, Wellbore Stability is a gordian technique difficult problem for restriction China's oil probing always.For keeping wellbore stability, Drilling ratio in drilling process is reached to the stratum of being rich in clay mineral of 90%, the oil base drilling fluid that adopts creeps into more, but for the fissured formation of fracture development, oil base drilling fluid still can be missed and be entered stratum.Particularly for the mixed wettability stratum of growing a large amount of microfissure, such as shale formation, mudstone stratum, sandstone formation, under the effect of capillary force, oil base drilling fluid filtrate more easily enters stratum, thus increase the stress intensity factor of crack tip, make crack propagation, and then cause hole instability.From microcosmic angle analysis, the interfacial characteristics in the boundary layer between oil base drilling fluid and formation rock, especially wetting property controls oil base drilling fluid to enter formation rock, and the key of all physical actions and chemical action between oil base drilling fluid and formation rock.
Change due to formation rock and oil base drilling fluid system wetting state can affect the stress intensity factor of crack tip, based on Theory of Fracture Mechanics, when stress intensity factor exceedes the fracture toughness of formation rock, crack is expanded, borehole well instability, therefore the wetting state of formation rock and oil base drilling fluid system needs a security window.Oil base drilling fluid architectural feature directly affects the wetting state of formation rock and oil base drilling fluid system to a great extent, and then affect the stability of the borehole wall, therefore the wetting state according to formation rock and oil base drilling fluid system designs oil base drilling fluid parameter, significant for maintenance wellbore stability.
Application publication number is the lost circulation prevention drilling fluid system that the patent of invention of CN103045198A discloses the use of a kind of gasser, its formula is bentonitic clay 1-5, ammonium salt 0.1-1, coating agent 0.1-1, fluid loss agent 0.1-1, calcium carbonate 1-5, potassium chloride 1-5, surplus is water, and above ratio is all by weight, unit is kilogram, according to above-mentioned formulated drilling fluid and for drilling well.
Application publication number is the reservoir protection drilling fluid system that the patent of invention of CN103045194A discloses the use of a kind of gasser, and its formula is bentonitic clay 1-5, ammonium salt 0.1-1; coating agent 0.1-1; sulfonated gilsonite 1-5, sulfonated lignite 1-5, film forming agent 0.5-5; calcium carbonate 1-5; potassium chloride 1-5, surplus is water, and above ratio is all by weight; unit is kilogram, according to above-mentioned formulated drilling fluid and for drilling process.
The drilling fluid system of above-mentioned two patents all has that dehydration is little, good rheological property, can keep the advantages such as wellbore stability, but the formula of this drilling fluid system is rule of thumb optimized, its practical application effect of qualitative evaluation is carried out by improving property of drilling fluid, the performance of drilling fluid may be too high in addition, thus cause cost to improve.Therefore, being badly in need of the method for designing of a kind of drilling liquid parameter of exploitation, keeping wellbore stability by controlling drilling liquid parameter, this development for China's oil probing industry has important social effect and economic implications.
Summary of the invention
For solving problems of the prior art, the invention provides a kind of method for designing of oil base drilling fluid parameter, it comprises the following steps according to sequencing:
Step one: by physical property and the structural property of experimental test formation rock;
Step 2: according to physical property and the structural property of formation rock, set up the comprehensive characterization model of typical mineral, the pore texture of formation rock, oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state, and draw the graph of a relation between oil base drilling fluid parameter and wetting state;
Step 3: set up formation rock and the stability of wellbore by mechanics model of oil base drilling fluid system under wetting state condition, and draw the graph of a relation between oil base drilling fluid parameter and wellbore stability;
Step 4: according to the graph of a relation between oil base drilling fluid parameter and wellbore stability, determines oil base drilling fluid parameter.
The method for designing of oil base drilling fluid parameter of the present invention, it is the parameter designing oil base drilling fluid based on formation characteristics and stratum and fluid interface characteristic, the design of oil base drilling fluid parameter is made to have more science and theoretical foundation, effectively to prevent borehole well instability, prevent the generation of down hole problem, the performance simultaneously avoiding oil base drilling fluid is too high, the cost of conservative control oil base drilling fluid.
Preferably, in step one, at least get ten pieces of formation rocks, test its physical property and structural property respectively.
In above-mentioned either a program preferably, the mineral constituent of X-ray diffraction experimental test formation rock is adopted.Method of X-ray diffraction has does not damage formation rock sample, pollution-free, quick, measuring accuracy advantages of higher to mineral constituent.
In above-mentioned either a program preferably, total content of organic carbon (TOC), Kerogen type, the degree of ripeness of thermal decomposition test and vitrinite reflectance experimental test formation rock is adopted.In thermal decomposition test, the consumption of the formation rock sample used is few, simple to operation, and speed is fast, and analysis cost is low, and test result is accurate, can evaluate the total content of organic carbon of formation rock, Kerogen type.Adopt the degree of ripeness of vitrinite reflectance experimental test formation rock.Organic thermal evolution process and the evolutionary process of vitrinite closely related, therefore vitrinite reflectance is good maturity of organic matter index, and organic thermal metamorphism is darker, and vitrinite reflectance is larger.
In above-mentioned either a program preferably, the distribution of pores of scanning electron microscope, transmission electron microscope, CT experimental test formation rock is adopted.By scanning electron microscope (SEM) and transmission electron microscope (TEM), can two-dimentional porosity distribution in qualitative observation formation rock; By CT (CT), can three-dimensional pore space distribution characteristics in qualitative observation formation rock.
In above-mentioned either a program preferably, the factor of porosity of focused ion beam test, nitrogen adsorption test formation testing rock is adopted.By focused ion beam (FIB) test and nitrogen adsorption test, can the factor of porosity of quantitatively characterizing formation rock.
In above-mentioned either a program preferably, the fracture toughness of Brazilian diametral compression test formation testing rock is adopted.
In above-mentioned either a program preferably, in step 2, the foundation of the comprehensive characterization model of the pore texture of typical mineral, formation rock, oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state, it comprises the following steps according to sequencing:
Step one: formation rock is made ternary phase diagram according to the percentage by weight of silicate mineral, carbonate mineral, clay mineral three quasi-representative mineral, analyze the mineral constituent of having surveyed formation rock, and classify according to the drop point of mineral constituent in ternary phase diagram;
Step 2: the canonical measure surface of preparing typical mineral formation rock respectively;
Step 3: the contact angle of canonical measure surface under oil base drilling fluid effect measuring typical mineral formation rock respectively, and the test data of the total content of organic carbon of formation rock corresponding to combining respectively, Kerogen type, pore texture, analyze the impact of typical mineral, total content of organic carbon, factor of porosity formation rock and oil base drilling fluid system wetting state;
Step 4: by adjustment ow ratio and emulsifying agent addition, the oil base drilling fluid of preparation different performance, and measure its emulsion-breaking voltage, viscosity, pH value, API filter vector (the filter vector under room temperature 0.7MPa), HTHP filter vector (High Temperature High Pressure filter vector);
Step 5: the contact angle of canonical measure surface under the oil base drilling fluid effect of different performance measuring typical mineral formation rock respectively, analyzes the impact of oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state;
Step 6: according to the test data of the percentage by weight of typical mineral, total content of organic carbon, factor of porosity, oil base drilling fluid parameter, contact angle, set up the comprehensive characterization model of formation rock and oil base drilling fluid system wetting state.
In above-mentioned either a program preferably, analyze the mineral constituent of having surveyed formation rock, be at least quasi-representative mineral.
In above-mentioned either a program preferably, analyzing the mineral constituent of having surveyed formation rock, is three quasi-representative mineral.
Be taken to few ten pieces of formation rocks, test its mineral constituent respectively, and classify according to the drop point of mineral constituent in ternary phase diagram, mineral constituent is calculated by weight percentage.Three quasi-representative mineral are silicate mineral, carbonate mineral, clay mineral.If which class mineral constituent accounts for leading in formation rock, then which class mineral formation rock this formation rock is.Quartz, potassium feldspar, plagioclase are silicate mineral; Kalzit, rauhkalk are carbonate mineral.
In above-mentioned either a program preferably, the shape of the canonical measure sample of described typical mineral formation rock is cylindrical.
In above-mentioned either a program preferably, described columniform upper and lower end face is parallel.
In above-mentioned either a program preferably, described columniform upper and lower end face carries out mechanical buffing process.
In above-mentioned either a program preferably, described columniform upper and lower end face carries out argon ion polishing.
In above-mentioned either a program preferably, described columniform height is not more than 20mm.
In above-mentioned either a program preferably, described columniform diameter is at least 10mm.
For guaranteeing measuring accuracy, two end faces of cylindrical measurement sample answer keeping parallelism, and two end faces should carry out mechanical buffing process or argon ion polishing, and when guaranteeing to amplify 1000 times under an optical microscope, end face is smooth, no marking still.
In above-mentioned either a program preferably, video optical test is adopted to measure the contact angle of canonical measure surface under oil base drilling fluid effect of typical mineral formation rock.In video optical test, formation rock sample three axle is located, measure accurately.
In above-mentioned either a program preferably, diesel oil, water, primary emulsion, auxiliary emulsifying agent, lime chloride, organophilic clay, filtrate reducer I, filtrate reducer II, alkalinity control agent, weighting agent is contained in described oil base drilling fluid.Primary emulsion can select VERSAMUL, auxiliary emulsifying agent can select that VERSACOAT HF, organophilic clay can select VG-PLUS, filtrate reducer I can select VERSATROL, filtrate reducer II can select ECOTROLRD, alkalinity control agent that calcium oxide, weighting agent can be selected to select barite.
In above-mentioned either a program preferably, described oil base drilling fluid parameter is emulsion-breaking voltage, pH value, ow ratio, emulsifying agent addition.The oil base drilling fluid key parameter that above-mentioned four parameters will design for the present invention.Ow ratio is the ratio of diesel oil and water, and emulsifying agent addition is primary emulsion addition and auxiliary emulsifying agent addition.
When configuring oil base drilling fluid, need the following performance of test oil base drilling fluid: emulsion-breaking voltage (ES), pH value, viscosity (AV), API filter vector, HTHP filters vector.Because AV, API, HTHP of oil base drilling fluid have industry standard, corresponding requirement must be reached, therefore not need to adopt method for designing of the present invention to design this three parameters, only need design key parameter.
In above-mentioned either a program preferably, the comprehensive characterization model of described formation rock and oil base drilling fluid system wetting state is
θ＝F(ES，PH，O/W，W
e，TOC，φ，W
1，W
2，W
3)
Wherein, the contact angle of θ---formation rock and oil base drilling fluid system, °;
ES---emulsion-breaking voltage, V;
PH---pH value;
O/W---ow ratio;
W
e---emulsifying agent addition, %;
TOC---total content of organic carbon, %;
φ---factor of porosity, %;
W
1, W
2, W
3---the percentage by weight of three quasi-representative mineral, %.
In above-mentioned either a program preferably, in step 3, the foundation of formation rock and the oil base drilling fluid system stability of wellbore by mechanics model under wetting state condition, it comprises the following steps according to sequencing:
Step one: the stress intensity factor calculating wellbore I type crack tip;
Step 2: according to Theory of Fracture Mechanics, sets up formation rock and the stability of wellbore by mechanics model of oil base drilling fluid system under wetting state condition;
Step 3: in conjunction with stability of wellbore by mechanics model and formation rock and oil base drilling fluid system wetting state comprehensive characterization model, analyzes oil base drilling fluid parameter to the impact of wellbore stability, and draws the graph of a relation between oil base drilling fluid parameter and wellbore stability.
In above-mentioned either a program preferably, the computing formula of the stress intensity factor of described wellbore I type crack tip is
Wherein, σ---terrestrial stress, MPa;
P
f---fluid column pressure, MPa;
γ---the interfacial tension between oil base drilling fluid and local water, mN/m;
β---the angle between crack wall and axis, crack, °;
ω---fracture width, m;
The contact angle of θ---formation rock and oil base drilling fluid system, °;
The halfwidth in H---crack, m;
L---microfracture centre distance stitches the distance of sharp drilling fluid leading edge, m.
In above-mentioned either a program preferably, described formation rock and the oil base drilling fluid system stability of wellbore by mechanics model under wetting state condition is K
i≤ K
iC,
Wherein, K
i---the stress intensity factor of wellbore I type crack tip;
K
iC---the fracture toughness of formation rock.
In above-mentioned either a program preferably, described oil base drilling fluid is used in the shale formation of Sichuan, its parameter window is, ow ratio is 80-95:5-20, primary emulsion addition is 0.8-2.5%, auxiliary emulsifying agent addition is 1.3-2.8%, pH value is 8.0-9.5, emulsion-breaking voltage is 400-853V.
In above-mentioned either a program preferably, described oil base drilling fluid is used in Karamay, Xinjiang mudstone stratum, its parameter window is, ow ratio is 80-90:10-20, primary emulsion addition is 1.0-2.2%, auxiliary emulsifying agent addition is 1.6-3.1%, pH value is 7.0-10, emulsion-breaking voltage is 400-841V.
In above-mentioned either a program preferably, described oil base drilling fluid is used in the sandstone formation of Yunnan, its parameter window is, ow ratio is 75-85:15-25, primary emulsion addition is 0.95-2.0%, auxiliary emulsifying agent addition is 1.4-2.7%, pH value is 7.0-9.0, emulsion-breaking voltage is 400-940V.
The present invention utilizes wetting theory to design the key parameter of oil base drilling fluid, first by physical property and the structural property of the characterizing formation rocks such as X-ray diffraction technology, microcell image analysis technology, fluid implantttion technique, the impact of the typical mineral feature of research formation rock, architectural feature and oil base drilling fluid key parameter formation rock and the oil base drilling fluid system wetting state of then learning a skill by the video light of advanced person, set up comprehensive characterization model, then set up the stability of wellbore by mechanics model considering formation rock and oil base drilling fluid system wetting state according to Theory of Fracture Mechanics.Based on the characteristic of drilled strata rock, above-mentioned two models of integrated application, Research on Oil base drilling fluid key parameter is on the impact of wellbore stability, set up the graph of a relation between oil base drilling fluid key parameter and wellbore stability, and the window of oil base drilling fluid key parameter is designed according to graph of a relation, effectively to keep wellbore stability, prevent the generation of down hole problem, the cost of conservative control oil base drilling fluid.Method for designing of the present invention is simple, be easy to operation; The window of designed oil base drilling fluid key parameter is accurately reasonable, and window is wider, is easy to execute-in-place; The action effect of wellbore stability can be kept by quantitative evaluation oil base drilling fluid, to the development of China's oil probing industry, there is important social effect and economic implications.
Accompanying drawing explanation
Fig. 1 is a preferred embodiment process flow diagram of the method for designing according to oil base drilling fluid parameter of the present invention;
Fig. 2 is the formation rock mineral constituent ternary phase diagram embodiment illustrated in fig. 1 of the method for designing according to oil base drilling fluid parameter of the present invention;
Fig. 3 is the contact angle of canonical measure surface under oil base drilling fluid effect of three kinds of typical mineral formation rocks embodiment illustrated in fig. 1 of method for designing according to oil base drilling fluid parameter of the present invention;
Wherein, (a) and (b) is respectively the contact angle of canonical measure surface under oil base drilling fluid effect of silicate mineral and carbonate mineral formation rock.
Fig. 4 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 1 pH value be 6.5 and different emulsion-breaking voltage under, the graph of a relation between contact angle and silicate mineral content;
Fig. 5 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 1 formation rock physical property and structural property one timing, oil base drilling fluid under different PH, the graph of a relation between contact angle and emulsion-breaking voltage;
Fig. 6 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 1 formation rock physical property and structural property one timing, the emulsion-breaking voltage of oil base drilling fluid and the graph of a relation between pH value and stress intensity factor;
Fig. 7 is the formation rock mineral constituent ternary phase diagram of another preferred embodiment of method for designing according to oil base drilling fluid parameter of the present invention;
Fig. 8 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 7 pH value be 6.5 and different emulsion-breaking voltage under, the graph of a relation between contact angle and silicate mineral content;
Fig. 9 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 7 formation rock physical property and structural property one timing, oil base drilling fluid under different PH, the graph of a relation between contact angle and emulsion-breaking voltage;
Figure 10 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 7 formation rock physical property and structural property one timing, the emulsion-breaking voltage of oil base drilling fluid and the graph of a relation between pH value and stress intensity factor;
Figure 11 is the formation rock mineral constituent ternary phase diagram of another preferred embodiment of method for designing according to oil base drilling fluid parameter of the present invention;
Figure 12 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 11 pH value be 6.5 and different emulsion-breaking voltage under, the graph of a relation between contact angle and silicate mineral content;
Figure 13 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 11 formation rock physical property and structural property one timing, oil base drilling fluid under different PH, the graph of a relation between contact angle and emulsion-breaking voltage;
Figure 14 be according to oil base drilling fluid parameter of the present invention method for designing embodiment illustrated in fig. 11 formation rock physical property and structural property one timing, the emulsion-breaking voltage of oil base drilling fluid and the graph of a relation between pH value and stress intensity factor.
Embodiment
In order to further understand summary of the invention of the present invention, elaborate the present invention below in conjunction with specific embodiment.
Embodiment one:
As shown in Figure 1, the present embodiment selects the shale formation of Sichuan Province China block, designs oil base drilling fluid key parameter window based on formation rock and oil base drilling fluid system wetting theory.A method for designing for oil base drilling fluid parameter, it comprises the following steps according to sequencing:
Step one: by physical property and the structural property of experimental test formation rock.
Get ten pieces of shale formation samples, test its physical property and structural property respectively.Adopt the mineral constituent of X-ray diffraction experimental test formation rock; Adopt total content of organic carbon (TOC), Kerogen type, the degree of ripeness of thermal decomposition test and vitrinite reflectance experimental test formation rock; By scanning electron microscope (SEM) and transmission electron microscope (TEM), the two-dimentional porosity distribution in qualitative observation formation rock; By CT (CT), the three-dimensional pore space distribution characteristics in qualitative observation formation rock;
Adopt focused ion beam (FIB) test and nitrogen adsorption test, the factor of porosity of quantitatively characterizing formation rock; Adopt the fracture toughness of Brazilian diametral compression test formation testing rock.The porosity distribution of ten pieces of formation rock samples is, in brittle mineral, microfissure is grown, organic hole also comparative development.From survey and get rid of the larger sample of error ten pieces of formation rock samples after, do subsequent design with remaining sample.The present embodiment chooses the data of three groups of typical samples exemplarily from remaining sample, the mineral constituent of these three pieces of formation rock samples, total content of organic carbon, Kerogen type, vitrinite reflectance test result are as shown in table 1.1, and the factor of porosity of three pieces of formation rock samples, fracture toughness test result are as shown in table 1.2.
The physical property test result of table 1.1 three pieces of formation rock samples
The factor of porosity of table 1.2 three pieces of formation rock samples and fracture toughness test result
| Sample number into spectrum | Factor of porosity (%) | Fracture toughness (MPam 1/2) |
| 1# | 4.02 | 0.63 |
| 2# | 4.61 | 0.60 |
| 3# | 2.54 | 0.85 |
Step 2: according to physical property and the structural property of formation rock, set up the comprehensive characterization model of typical mineral, the pore texture of formation rock, oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state, and draw the graph of a relation between oil base drilling fluid parameter and wetting state.
The foundation of the comprehensive characterization model of the pore texture of typical mineral, formation rock, oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state, it comprises the following steps according to sequencing:
(1) formation rock is made ternary phase diagram according to the percentage by weight of silicate mineral, carbonate mineral, clay mineral three quasi-representative mineral, as shown in Figure 2, the percentage by weight of three quasi-representative mineral is respectively W
1, W
2, W
3, analyze the mineral constituent of having surveyed three pieces of formation rocks, and classify according to the drop point of mineral constituent in ternary phase diagram.1# sample is silicate mineral formation rock, and 2# sample is carbonate mineral formation rock, and 3# sample is clay mineral formation rock.
(2) prepare the canonical measure surface of silicate mineral formation rock, carbonate mineral formation rock, clay mineral formation rock respectively, measure for wetting state.
The shape of the canonical measure sample of three quasi-representative mineral formation rocks is cylindrical, and its upper and lower end face is parallel.The height of cylindrical sample is 20mm, and diameter is 10mm.Columniform upper and lower end face need carry out mechanical buffing process or argon ion polishing, and when guaranteeing to amplify 1000 times under an optical microscope, end face is smooth, no marking still.
(3) video optical test is adopted to measure the contact angle θ of canonical measure surface under oil base drilling fluid effect of silicate mineral formation rock, carbonate mineral formation rock, clay mineral formation rock respectively, as shown in Figure 3, and the test data of the total content of organic carbon of formation rock corresponding to combining respectively, Kerogen type, pore texture, analyze the impact of typical mineral, total content of organic carbon, factor of porosity formation rock and oil base drilling fluid system wetting state.
Analysis is carried out to the formation rock sample of the present embodiment known, different typical minerals (silicate mineral, carbonate mineral, clay mineral) and the interfacial characteristics of organic formation rock and oil base drilling fluid system have appreciable impact, but influence degree and influence mode different.Such as, along with the increase of silicate mineral or carbonate mineral content, contact angle increases gradually, and along with the increase of the content of organic matter or the increase of degree of ripeness, contact angle has a declining tendency.Fig. 4 for pH value be 6.5 and different emulsion-breaking voltage under, the graph of a relation between contact angle and silicate mineral content.
(4) by adjustment ow ratio and emulsifying agent addition, the oil base drilling fluid of preparation different performance, and measure its emulsion-breaking voltage, viscosity, pH value, API filter vector, HTHP filters vector.
The oil base drilling fluid component of the present embodiment is as follows, calculates by weight percentage: diesel oil, water, primary emulsion (VERSAMUL) 1.7%, auxiliary emulsifying agent (VERSACOAT HF) 2.3%, lime chloride 4.3%, organophilic clay (VG-PLUS) 0.6%, filtrate reducer I (VERSATROL) 2.8%, filtrate reducer II (ECOTROL RD) 0.15%, alkalinity control agent (calcium oxide) 2.8%, weighting agent (barite).
Adjustment ow ratio and emulsifying agent addition, the oil base drilling fluid of configuration different performance.Oil base drilling fluid key parameter is emulsion-breaking voltage (ES), pH value, ow ratio (O/W), emulsifying agent addition (W
e).Emulsifying agent addition is primary emulsion addition and auxiliary emulsifying agent addition.
(5) adopt video optical test to measure the contact angle of canonical measure surface under the oil base drilling fluid effect of different performance of typical mineral formation rock respectively, analyze the impact of oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state.
Analysis is carried out to the formation rock sample of the present embodiment known, when characteristic one timing of formation rock, along with the rising of ow ratio, emulsifying agent addition and emulsion-breaking voltage, the contact angle of formation rock and oil base drilling fluid system reduces, but the rupture strength factor of crack tip increases, under different PH and filter loss situation, the amplitude that rupture strength factor increases is different.
(6) according to the test data of the percentage by weight of typical mineral, total content of organic carbon, factor of porosity, oil base drilling fluid parameter, contact angle, the comprehensive characterization model of formation rock and oil base drilling fluid system wetting state is set up.
The foundation of this comprehensive characterization model considers the factors such as formation rock mineral constituent characteristic, pore structure properties and oil base drilling fluid performance parameter.
In the present embodiment, the comprehensive characterization model of formation rock and oil base drilling fluid system wetting state is
θ＝F(ES，PH，O/W，W
e，TOC，φ，W
1，W
2，W
3)
Wherein, the contact angle of θ---formation rock and oil base drilling fluid system, °;
ES---emulsion-breaking voltage, V;
PH---pH value;
O/W---ow ratio;
W
e---emulsifying agent addition, %;
TOC---total content of organic carbon, %;
φ---factor of porosity, %;
W
1, W
2, W
3---the percentage by weight of three quasi-representative mineral, %.
Fig. 5 be formation rock physical property and structural property one timing, oil base drilling fluid under different PH, the graph of a relation between contact angle and emulsion-breaking voltage.
Step 3: set up formation rock and the stability of wellbore by mechanics model of oil base drilling fluid system under wetting state condition, and draw the graph of a relation between oil base drilling fluid parameter and wellbore stability.
The foundation of formation rock and the oil base drilling fluid system stability of wellbore by mechanics model under wetting state condition, it comprises the following steps according to sequencing:
(1) stress intensity factor of wellbore I type crack tip is calculated.
In drilling process, oil base drilling fluid enters formation rock along bed plane or crack, produces capillary force, change the stress state of seam point at the seam point of microfracture.
From geometric relationship, when liquid is oil base drilling fluid, capillary force is
wherein, γ---the interfacial tension between oil base drilling fluid and local water, mN/m;
β---the angle between crack wall and axis, crack, °;
ω---fracture width, m;
During oil base drilling fluid drilling well, the computing formula of the stress intensity factor of wellbore I type crack tip is
Wherein, σ---terrestrial stress, MPa;
P
f---fluid column pressure, MPa;
γ---the interfacial tension between oil base drilling fluid and local water, mN/m;
β---the angle between crack wall and axis, crack, °;
ω---fracture width, m;
The contact angle of θ---formation rock and oil base drilling fluid system, °;
The halfwidth in H---crack, m;
L---microfracture centre distance stitches the distance of sharp drilling fluid leading edge, m.
(2) according to Theory of Fracture Mechanics, formation rock and the stability of wellbore by mechanics model of oil base drilling fluid system under wetting state condition is set up.
When oil base drilling fluid enters formation rock, the contact angle of formation rock and oil base drilling fluid system is by affecting the stress intensity factor in I type crack, and from fracture mechanics analysis, when stress intensity factor is greater than fracture toughness, crack is expanded, borehole well instability.For keeping wellbore stability, prevent the generation of down hole problem, the contact angle of formation rock and oil base drilling fluid system must in safe range, to guarantee that stress intensity factor is less than fracture toughness.Therefore, formation rock and the oil base drilling fluid system stability of wellbore by mechanics model under wetting state condition is K
i≤ K
iC,
Wherein, K
i---the stress intensity factor of wellbore I type crack tip;
K
iC---the fracture toughness of formation rock.
(3) in conjunction with stability of wellbore by mechanics model and formation rock and oil base drilling fluid system wetting state comprehensive characterization model, analyze oil base drilling fluid parameter to the impact of wellbore stability, and draw the graph of a relation between oil base drilling fluid parameter and wellbore stability.
Fig. 6 is in formation rock physical property and structural property one timing, the emulsion-breaking voltage of oil base drilling fluid and the graph of a relation between pH value and stress intensity factor.
Step 4: according to the graph of a relation between oil base drilling fluid parameter and wellbore stability, determines oil base drilling fluid parameter.
Oil base drilling fluid is used in the shale formation of Sichuan by this enforcement, and its key parameter window is: ow ratio is 80-95:5-20, primary emulsion addition is 0.8-2.5%, auxiliary emulsifying agent addition is 1.3-2.8%, pH value is 8.0-9.5, emulsion-breaking voltage is 400-853V.
Embodiment two:
The present embodiment selects the mudstone stratum of Karamay, Xinjiang block, and design oil base drilling fluid key parameter window based on formation rock and oil base drilling fluid system wetting theory, its method for designing is identical with embodiment one,
Unlike:
Get 20 pieces of mudstone stratum samples, test its physical property and structural property respectively, from survey and get rid of the larger sample of error 20 pieces of formation rock samples after, do subsequent design with remaining sample.The present embodiment chooses the data of three groups of typical samples exemplarily from remaining sample, the mineral constituent of these three pieces of formation rock samples, total content of organic carbon, Kerogen type, vitrinite reflectance test result are as shown in table 2.1, and the factor of porosity of three pieces of formation rock samples, fracture toughness test result are as shown in table 2.2.
The physical property test result of table 2.1 three pieces of formation rock samples
The factor of porosity of table 2.2 three pieces of formation rock samples and fracture toughness test result
| Sample number into spectrum | Factor of porosity (%) | Fracture toughness (MPam 1/2) |
| 1# | 4.32 | 0.53 |
| 2# | 4.51 | 0.63 |
| 3# | 5.54 | 0.58 |
Formation rock is made ternary phase diagram according to the percentage by weight of silicate mineral, carbonate mineral, clay mineral three quasi-representative mineral, and as shown in Figure 7, the percentage by weight of three quasi-representative mineral is respectively W
1, W
2, W
3, analyze the mineral constituent of having surveyed three pieces of formation rocks, and classify according to the drop point of mineral constituent in ternary phase diagram.1# sample and 2# sample are silicate mineral formation rock, and 3# sample is carbonate mineral formation rock.
The shape of the canonical measure sample of two quasi-representative mineral formation rocks is cylindrical, and its upper and lower end face is parallel.The height of cylindrical sample is 15mm, and diameter is 15mm.Columniform upper and lower end face need carry out mechanical buffing process or argon ion polishing, and when guaranteeing to amplify 1000 times under an optical microscope, end face is smooth, no marking still.
Analysis is carried out to the formation rock sample of the present embodiment known, different typical minerals (silicate mineral, carbonate mineral, clay mineral) and the interfacial characteristics of organic formation rock and oil base drilling fluid system have appreciable impact, but influence degree and influence mode different.Fig. 8 for pH value be 6.5 and different emulsion-breaking voltage under, the graph of a relation between contact angle and silicate mineral content.
The oil base drilling fluid component of the present embodiment is as follows, calculates by weight percentage: diesel oil, water, primary emulsion (VERSAMUL) 1.4%, auxiliary emulsifying agent (VERSACOAT HF) 2.1%, lime chloride 5.0%, organophilic clay (VG-PLUS) 0.7%, filtrate reducer I (VERSATROL) 2.4%, filtrate reducer II (ECOTROL RD) 0.25%, alkalinity control agent (calcium oxide) 3.0%, weighting agent (barite).
Adjustment ow ratio and emulsifying agent addition, the oil base drilling fluid of configuration different performance.Oil base drilling fluid key parameter is emulsion-breaking voltage (ES), pH value, ow ratio (O/W), emulsifying agent addition (W
e).Emulsifying agent addition is primary emulsion addition and auxiliary emulsifying agent addition.
Fig. 9 be formation rock physical property and structural property one timing, oil base drilling fluid under different PH, the graph of a relation between contact angle and emulsion-breaking voltage.
Figure 10 is in formation rock physical property and structural property one timing, the emulsion-breaking voltage of oil base drilling fluid and the graph of a relation between pH value and stress intensity factor.
Oil base drilling fluid is used in Karamay, Xinjiang mudstone stratum by this enforcement, and its key parameter window is: ow ratio is 80-90:10-20, primary emulsion addition is 1.0-2.2%, auxiliary emulsifying agent addition is 1.6-3.1%, pH value is 7.0-10, emulsion-breaking voltage is 400-841V.
Embodiment three:
The present embodiment selects the sandstone formation of Chinese yunnan block, and design oil base drilling fluid key parameter window based on formation rock and oil base drilling fluid system wetting theory, its method for designing is identical with embodiment one, unlike:
Get 25 pieces of sandstone formation samples, test its physical property and structural property respectively, from survey and get rid of the larger sample of error 25 pieces of formation rock samples after, do subsequent design with remaining sample.The present embodiment chooses the data of three groups of typical samples exemplarily from remaining sample, the mineral constituent of these three pieces of formation rock samples, total content of organic carbon, Kerogen type, vitrinite reflectance test result are as shown in table 3.1, and the factor of porosity of three pieces of formation rock samples, fracture toughness test result are as shown in table 3.2.
The physical property test result of table 3.1 three pieces of formation rock samples
The factor of porosity of table 3.2 three pieces of formation rock samples and fracture toughness test result
| Sample number into spectrum | Factor of porosity (%) | Fracture toughness (MPam 1/2) |
| 1# | 5.72 | 0.43 |
| 2# | 6.21 | 0.72 |
| 3# | 5.64 | 0.67 |
Formation rock is made ternary phase diagram according to the percentage by weight of silicate mineral, carbonate mineral, clay mineral three quasi-representative mineral, and as shown in figure 11, the percentage by weight of three quasi-representative mineral is respectively W
1, W
2, W
3, analyze the mineral constituent of having surveyed three pieces of formation rocks, and classify according to the drop point of mineral constituent in ternary phase diagram.1# sample, 2# sample, 3# sample are silicate mineral formation rock.
The shape of the canonical measure sample of one quasi-representative mineral formation rock is cylindrical, and its upper and lower end face is parallel.The height of cylindrical sample is 10mm, and diameter is 20mm.Columniform upper and lower end face need carry out mechanical buffing process or argon ion polishing, and when guaranteeing to amplify 1000 times under an optical microscope, end face is smooth, no marking still.
Analysis is carried out to the formation rock sample of the present embodiment known, different typical minerals (silicate mineral, carbonate mineral, clay mineral) and the interfacial characteristics of organic formation rock and oil base drilling fluid system have appreciable impact, but influence degree and influence mode different.Figure 12 for pH value be 6.5 and different emulsion-breaking voltage under, the graph of a relation between contact angle and silicate mineral content.
The oil base drilling fluid component of the present embodiment is as follows, calculates by weight percentage: diesel oil, water, primary emulsion (VERSAMUL) 1.6%, auxiliary emulsifying agent (VERSACOAT HF) 2.5%, lime chloride 4.0%, organophilic clay (VG-PLUS) 0.5%, filtrate reducer I (VERSATROL) 2.0%, filtrate reducer II (ECOTROL RD) 0.25%, alkalinity control agent (calcium oxide) 2.8%, weighting agent (barite).
Adjustment ow ratio and emulsifying agent addition, the oil base drilling fluid of configuration different performance.Oil base drilling fluid key parameter is emulsion-breaking voltage (E), pH value, ow ratio (O/W), emulsifying agent addition (W
e).Emulsifying agent addition is primary emulsion addition and auxiliary emulsifying agent addition.
Figure 13 be formation rock physical property and structural property one timing, oil base drilling fluid under different PH, the graph of a relation between contact angle and emulsion-breaking voltage.
Figure 14 is in formation rock physical property and structural property one timing, the emulsion-breaking voltage of oil base drilling fluid and the graph of a relation between pH value and stress intensity factor.
Oil base drilling fluid is used in the sandstone formation of Yunnan by this enforcement, and its key parameter window is: ow ratio is 75-85:15-25, primary emulsion addition is 0.95-2.0%, auxiliary emulsifying agent addition is 1.4-2.7%, pH value is 7.0-9.0, emulsion-breaking voltage is 400-940V.
Those skilled in the art are understood that, the method for designing of oil base drilling fluid parameter of the present invention comprises the summary of the invention of the invention described above instructions and the combination in any of embodiment part and each several part shown by accompanying drawing, as space is limited and not have each scheme of these combination formations to describe one by one for making instructions simple and clear.Within the spirit and principles in the present invention all, any amendment made, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a method for designing for oil base drilling fluid parameter, it comprises the following steps according to sequencing:
Step one: by physical property and the structural property of experimental test formation rock;
Step 2: according to physical property and the structural property of formation rock, set up the comprehensive characterization model of typical mineral, the pore texture of formation rock, oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state, and draw the graph of a relation between oil base drilling fluid parameter and wetting state;
Step 3: set up formation rock and the stability of wellbore by mechanics model of oil base drilling fluid system under wetting state condition, and draw the graph of a relation between oil base drilling fluid parameter and wellbore stability;
Step 4: according to the graph of a relation between oil base drilling fluid parameter and wellbore stability, determines oil base drilling fluid parameter.
2. the method for designing of oil base drilling fluid parameter as claimed in claim 1, is characterized in that: in step one, at least gets ten pieces of formation rocks, test its physical property and structural property respectively.
3. the method for designing of oil base drilling fluid parameter as claimed in claim 2, is characterized in that: the mineral constituent adopting X-ray diffraction experimental test formation rock.
4. the method for designing of oil base drilling fluid parameter as claimed in claim 2, is characterized in that: the total content of organic carbon, Kerogen type, the degree of ripeness that adopt thermal decomposition test and vitrinite reflectance experimental test formation rock.
5. the method for designing of oil base drilling fluid parameter as claimed in claim 2, is characterized in that: the distribution of pores adopting scanning electron microscope, transmission electron microscope, CT experimental test formation rock.
6. the method for designing of oil base drilling fluid parameter as claimed in claim 5, is characterized in that: the factor of porosity adopting focused ion beam test, nitrogen adsorption test formation testing rock.
7. the method for designing of oil base drilling fluid parameter as claimed in claim 2, is characterized in that: the fracture toughness adopting Brazilian diametral compression test formation testing rock.
8. the method for designing of oil base drilling fluid parameter as claimed in claim 1, it is characterized in that: in step 2, the foundation of the comprehensive characterization model of the pore texture of typical mineral, formation rock, oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state, it comprises the following steps according to sequencing:
Step one: formation rock is made ternary phase diagram according to the percentage by weight of silicate mineral, carbonate mineral, clay mineral three quasi-representative mineral, analyze the mineral constituent of having surveyed formation rock, and classify according to the drop point of mineral constituent in ternary phase diagram;
Step 2: the canonical measure surface of preparing typical mineral formation rock respectively;
Step 3: the contact angle of canonical measure surface under oil base drilling fluid effect measuring typical mineral formation rock respectively, and the test data of the total content of organic carbon of formation rock corresponding to combining respectively, Kerogen type, pore texture, analyze the impact of typical mineral, total content of organic carbon, factor of porosity formation rock and oil base drilling fluid system wetting state;
Step 4: by adjustment ow ratio and emulsifying agent addition, the oil base drilling fluid of preparation different performance, and measure its emulsion-breaking voltage, viscosity, pH value, API filter vector, HTHP filters vector;
Step 5: the contact angle of canonical measure surface under the oil base drilling fluid effect of different performance measuring typical mineral formation rock respectively, analyzes the impact of oil base drilling fluid parameter formation rock and oil base drilling fluid system wetting state;
Step 6: according to the test data of the percentage by weight of typical mineral, total content of organic carbon, factor of porosity, oil base drilling fluid parameter, contact angle, set up the comprehensive characterization model of formation rock and oil base drilling fluid system wetting state.
9. the method for designing of oil base drilling fluid parameter as claimed in claim 8, is characterized in that: analyze the mineral constituent of having surveyed formation rock, be at least quasi-representative mineral.
10. the method for designing of oil base drilling fluid parameter as claimed in claim 9, is characterized in that: analyzing the mineral constituent of having surveyed formation rock, is three quasi-representative mineral.
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