CN117540650A - CO for clay-rich hypotonic oil reservoir 2 Saturation calculating method - Google Patents
CO for clay-rich hypotonic oil reservoir 2 Saturation calculating method Download PDFInfo
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- 239000004927 clay Substances 0.000 title claims abstract description 55
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- 239000012530 fluid Substances 0.000 claims abstract description 24
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 39
- 239000012071 phase Substances 0.000 claims description 33
- 230000014509 gene expression Effects 0.000 claims description 29
- 238000012937 correction Methods 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 9
- 150000001768 cations Chemical group 0.000 claims description 7
- 239000008398 formation water Substances 0.000 claims description 7
- 239000008346 aqueous phase Substances 0.000 claims description 4
- 239000002734 clay mineral Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- NAWXUBYGYWOOIX-SFHVURJKSA-N (2s)-2-[[4-[2-(2,4-diaminoquinazolin-6-yl)ethyl]benzoyl]amino]-4-methylidenepentanedioic acid Chemical compound C1=CC2=NC(N)=NC(N)=C2C=C1CCC1=CC=C(C(=O)N[C@@H](CC(=C)C(O)=O)C(O)=O)C=C1 NAWXUBYGYWOOIX-SFHVURJKSA-N 0.000 claims description 3
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- 238000001514 detection method Methods 0.000 abstract description 2
- 238000004364 calculation method Methods 0.000 description 14
- 238000002474 experimental method Methods 0.000 description 10
- 239000007789 gas Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
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- 238000010586 diagram Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
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- 239000005431 greenhouse gas Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012821 model calculation Methods 0.000 description 1
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Abstract
The invention discloses a method for preparing CO for a clay-rich hypotonic oil reservoir 2 The saturation calculating method belongs to the field of rock physical electromagnetic detection, and comprises the following steps: expanding the Rhoades capillary bundle model and the Waxman-Smits parallel conductivity model to conductivity equations considering multiphase fluid and clay effect effects, respectively; respectively solving the conductivity of each component of the two expanded equations simultaneously, and correcting parameters; obtaining a secondarily improved Rhoades capillary bundle model and a secondarily improved Waxman-Smits parallel model according to the corrected parameters, the fitting relation of the transmission factors and the saturation; calculating the CO in the clay-rich hypotonic oil reservoir according to the secondarily improved Rhoades capillary bundle model and the secondarily improved Waxman-Smits parallel model 2 Fluid saturation. The invention discloses a clay-rich reservoir CO 2 The method for calculating the reservoir oil seal storage saturation can effectively monitor the reservoir multiphase fluid saturation change.
Description
Technical Field
The invention belongs to the field of petrophysical electromagnetic detection, and particularly relates to a method for preparing CO aiming at a clay-rich hypotonic oil reservoir 2 Saturation calculation method.
Background
Carbon dioxide utilization and sealing technologyHas important strategic significance in the background of the challenges of climate change and sustainable development in the world today. The carbon dioxide utilization and sealing are a technical means, can effectively reduce the emission of greenhouse gases, and provide powerful support for realizing low-carbon economy and climate targets. Due to the complexity of the subsurface conditions, accurate monitoring of subsurface CO 2 The equal multicomponent fluid saturation distribution and variation technology has important significance in the field of electromagnetic exploration.
The prediction of saturation is related to the physical parameters of the rock reservoir. Formation factor is a parameter that reflects the relationship between rock reservoir porosity and water saturation and is basically defined as the ratio of the reservoir rock Dan Dianzu rate of fully saturated water to the formation water resistivity. The Archie's law predicts that the formation factor is a function of the rock characteristics, i.e., the porosity is a power law relationship. Equations show that the formation factor, which decreases in porosity, increases dramatically toward lower porosity regions. The formation factor is determined by the porosity, cementation index and other factors in the equation. Reservoirs at low porosity typically possess a higher cementation index reflecting the impact of cementation on current reservoir flow. The reservoir has a large difference in cementation index, affected by different degrees of cementation, pore geometry, clay content. The cementation index is approximately 2 for carbonate reservoirs with very low clay content, but the reservoir portion cementation index for higher clay content may be greater than 4. Since various rock types tend to be distributed in some clay-rich hypotonic reservoirs with high heterogeneity, modifying the cementation index and clay conductivity is a significant challenge.
With the deep exploration and development, a low-resistivity oil layer is continuously discovered, and is characterized in that the absolute value of the resistivity is smaller, and the difference of the resistivity of mineralized water in the stratum is smaller than 2Ω·m, so that the difficulty of the change of the saturation of multiphase fluid is increased. The prior art or theoretical methods fail to take into account the cementation index modification of reservoirs containing clay minerals and the characterization of the conductivity of multiphase fluids containing low resistivity reservoirs, and thus the calculated CO 2 Saturation is not accurate enough.
Disclosure of Invention
In order to solve the problems, the invention providesCO for clay-rich hypotonic oil reservoirs is disclosed 2 The saturation calculating method fully considers the influence of clay conductivity in the high clay-containing layer, corrects the two-phase transmission factor, the cementation index and the oil phase conductivity correction coefficient, and improves the CO 2 Accuracy of saturation calculation.
The technical scheme of the invention is as follows:
CO for clay-rich hypotonic oil reservoir 2 The saturation calculating method comprises the following steps:
step 1, respectively expanding a Rhoades capillary tube bundle model and a Waxman-Smits parallel conductivity model into a conductivity equation considering the influence of multiphase fluid and clay effect;
step 2, respectively solving the conductivity of each component of the two expanded equations simultaneously, and correcting parameters; parameters include cementation index, correction coefficient of oil phase conductivity and clay conductivity;
step 3, obtaining a primary improved Rhoades capillary bundle model and a primary improved Waxman-Smits parallel model according to the corrected parameters;
step 4, obtaining a secondarily improved Rhoades capillary bundle model and a secondarily improved Waxman-Smits parallel model according to the fitting relation between the transmission factor and the saturation;
step 5, calculating to obtain the CO in the clay-rich hypotonic oil reservoir according to the secondarily improved Rhoades capillary bundle model and the secondarily improved Waxman-Smits parallel model 2 Fluid saturation.
Further, the specific process of step 1 is as follows:
the Rhoades capillary bundle model and the Waxman-Smits parallel conductivity model are shown in the formula (2) and the formula (3), respectively:
σ tr ＝σ w φT+σ s (2)
wherein sigma tr The total conductivity of the Rhoades capillary bundle model; sigma (sigma) tw Parallel conductance for Waxman-SmitsTotal conductivity of the rate model; sigma (sigma) w Indicating the conductivity of formation water; phi represents porosity; t represents a transmission factor; sigma (sigma) s Represents the electrical conductivity of the clay; s is S w Represents water saturation; b represents cation average mobility; q (Q) v Represents the volume concentration of clay mineral exchange cations; m and n represent the bond index and the saturation index, respectively;
b and Q in a Waxman-Smits parallel conductivity model v The expression of (a) is as shown in the formula (4) -formula (5):
wherein CEC is rock cation exchange capacity; ρ G Is the average particle density of the rock;
the equations (2) and (3) are extended to conductivity equations considering the influence of multiphase fluid and clay effect, respectively, and are expressed as the equations (6) and (7):
σ trm ＝σ w φT w +σ o φT o +σ s (6)
wherein sigma trm Gross resistivity of the capillary bundle model affected by multiphase fluid and clay effects; sigma (sigma) twm The total conductivity of the parallel conductivity model to account for multiphase fluid and clay effects; sigma (sigma) o Representing the conductivity of the low resistivity oil phase; alpha s Is a correction coefficient of oil phase conductivity; t (T) w Representing the modified aqueous phase transport factor, T o The modified oil phase transmission factor is represented by the following expressions (8) - (9):
wherein L is the length of the straight line segment of the capillary; t is t 1 Is the thickness of the water layer; r is (r) 1 The sum of the radius of the circular hole air layer and the thickness of the oil layer; t is t 2 Is the thickness of the oil layer; r is (r) 2 Is the thickness radius of the round hole air layer.
Further, the specific process of step 2 is as follows:
the conductivity of each component of the two equations of the formula (6) and the formula (7) is solved simultaneously, and the conductivity is specifically shown as the formula (10) -formula (12):
φ m S w n σ w ＝φT w σ w (10)
φ m S w n α s σ o ＝φT o σ o (11)
solving the three equations to obtain corrected cementation indexes respectivelyCorrection coefficient of corrected oil phase conductivity +.>And conductivity of the modified clay->Specifically, the method is represented by the following formula (13) -formula (15):
further, the specific process of step 3 is as follows:
will beM, which is taken into formula (7), will +.>Alpha, which is carried into equation (7) s Will->Sigma brought into formula (6) s Finally, a primary improved Rhoades capillary bundle model and a primary improved Waxman-Smits parallel model are obtained, wherein the specific expression is (16) -formula (17):
further, the specific process of step 4 is as follows:
saturation of the water and oil phases in the pores is shown in the expression (18) -formula (19):
wherein t is 3 Is CO 2 The thickness of the gas layer; s is S w Represents water saturation; s is S o Is oil saturation;
and (3) performing relation fitting on the corrected water and oil two-phase transmission factors and the water and oil saturation to obtain a linear relation, wherein the specific expression is shown in the formula (20) -formula (21):
T w ～aS w (t 1 ,t 2 ,r 1 ,L)(20)
T o ～bS o (t 1 ,t 2 ,r 1 ,L)(21)
wherein a is a fitting coefficient of water saturation, and b is a fitting coefficient of oil saturation;
substituting the modified water-oil two-phase transmission factor and saturation fitting expression (20) -expression (21) into expression (16) -expression (17) to finally obtain a secondarily modified Rhoades capillary tube bundle model and a secondarily modified Waxman-Smits parallel model, wherein the specific expression is (22) -expression (23):
further, the specific process of step 5 is as follows:
two-shot modified Rhoades capillary bundle model (22) and two-shot modified Waxman-Smits parallel model (23) to obtain CO 2 As shown in formula (24),
wherein,representing CO 2 Is a saturation value of (a).
The invention has the beneficial technical effects that:
compared with the traditional Archie equation, the method considers the influence of the clay conductivity in the high-clay-content layer, so that the calculation accuracy of the equation is greatly improved;
compared with the Rhoades capillary tube bundle model in the prior art, the method expands the application range of the formula to oil, gas and water three-phase fluid, corrects the two-phase transmission factor and the clay conductivity, and greatly improves the calculation accuracy of the formula;
compared with the parallel model of the prior art, the method expands the application range of the formula to three-phase fluid, and re-corrects the two-phase transmission factor, the cementing index and the oil phase conductivity correction coefficient, so that the calculation accuracy of the formula is greatly improved;
the method redefines and fits the relation between the transmission factor and the water saturation, avoids the complex transmission factor to be solved in the prior art, and ensures that the CO content is calculated 2 The process of equalizing the saturation of the multiphase fluid is greatly simplified;
the method is suitable for reservoirs such as high clay content, low resistivity oil layers and the like, and can be widely used for monitoring CO 2 The oil displacement and the sealing saturation change are more effective in the prior practical engineering application.
Drawings
FIG. 1 is a schematic representation of a curved pore porous medium transport factor in accordance with the present invention.
FIG. 2 is a graph of the present invention for CO for a clay-rich hypotonic reservoir 2 A flow chart of a method of saturation calculation.
FIG. 3 is a comparison of five different conductivity models in experiment 1 of the present invention.
FIG. 4 is an Archie model calculation of CO in experiment 2 of the present invention 2 And comparing the relation between the saturation and the nuclear magnetic logging saturation to obtain a result graph.
FIG. 5 is a graph showing the calculation of CO using the modified parallel model of Waxman-Smits in experiment 2 of the present invention 2 And comparing the relation between the saturation and the nuclear magnetic logging saturation to obtain a result graph.
Detailed Description
The invention is described in further detail below with reference to the attached drawings and detailed description:
first, terms appearing in the present invention will be explained:
formation water resistivity: the resistivity of the water contained in reservoir rock is an important parameter for well logging interpretation. Generally, this can be determined by the following method: direct measurement of water sample, calculation of water sample analysis, natural potential method and resistivity-porosity intersection chart.
Two-phase transmission factor: a resistance value of the current in the pore space when passing through the pore space. T%<1) The ratio of the linear length corresponding to the current optimum path length is the inverse of the conductivity twist factor (le/l). FIG. 1 is a diagram of a curved pore porous medium transport factor model comprising rock particles, formation water, oil, CO 2 . L in FIG. 1 is the length of the capillary straight line segment, r 1 Is the sum of the radius of the circular hole air layer and the thickness of the oil layer, r 2 Radius of thickness of circular hole air layer, t 1 Is the thickness of the water layer, t 2 Is the thickness of the oil layer, t 3 Is CO 2 Thickness of the gas layer. The optimal conduction path for aqueous phase current is shown by the bold line in fig. 1.
The specific Archie model is shown in formula (1):
σ a ＝φ m S w n σ w (1)
wherein sigma a Representing the Archie model to calculate the total conductivity of the rock, S/m; phi represents porosity; m represents the cementation index, which is affected by the extent of cementation, pore geometry, clay content; n represents a saturation index; s is S w Represents water saturation; sigma (sigma) w Indicating the conductivity of the formation water.
Because different types of rock tend to be distributed in reservoirs with high heterogeneity, the cementation index varies greatly; in addition, equation (1) above ignores the effect of low conductivity reservoir on resistivity logging; failure to accurately calculate CO 2 Saturation changes in the oil displacement and sealing process.
In this example, a CO for a clay-rich hypotonic reservoir is disclosed 2 Saturation calculation method, specific calculation flowCheng Ru as shown in fig. 2, comprising the steps of:
step 1, respectively expanding a Rhoades capillary tube bundle model and a Waxman-Smits parallel conductivity model into a conductivity equation considering the influence of multiphase fluid and clay effect; the specific process is as follows:
the Rhoades capillary bundle model and the Waxman-Smits parallel conductivity model are shown in the formula (2) and the formula (3), respectively:
σ tr ＝σ w φT+σ s (2)
wherein sigma tr The total conductivity of the Rhoades capillary bundle model is S/m; sigma (sigma) tw The total conductivity, S/m, of the Waxman-Smits parallel conductivity model; sigma (sigma) w Represents the conductivity of formation water, S/m; phi represents porosity; t represents a transmission factor; sigma (sigma) s Represents the conductivity of clay, S/m; s is S w Represents water saturation; b represents the average mobility of cations, S.cm 3 /(mmol·m)；Q v Represents the volume concentration of clay mineral exchange cations, mmol.cm -3 The method comprises the steps of carrying out a first treatment on the surface of the m and n represent the cement index and the saturation index, respectively, in the present invention, m=2 and n=1.5 are set.
B and Q in a Waxman-Smits parallel conductivity model v The expression of (2) is as shown in the formulas (4) - (5):
wherein CEC is rock cation exchange capacity, mmol/100g; ρ G Is the average particle density of rock, g/cm 3 。
The formula (2) and the formula (3) are both expanded into oil, gas and water three-phase models, namely the formula (2) and the formula (3) are specifically expanded into conductivity equations considering the influence of multiphase fluid and clay effect respectively, and the expressions are shown as the formula (6) and the formula (7):
σ trm ＝σ w φT w +σ o φT o +σ s (6)
wherein sigma trm Gross resistivity of the capillary bundle model affected by multiphase fluid and clay effects; sigma (sigma) twm The total conductivity of the parallel conductivity model to account for multiphase fluid and clay effects; sigma (sigma) o Representing the conductivity of the low resistivity oil phase; alpha s Is a correction coefficient of oil phase conductivity; t (T) w Representing the modified aqueous phase transport factor, T o The modified oil phase transmission factor is represented by the following expressions (8) - (9):
wherein L is the length of the straight line segment of the capillary tube, and m; t is t 1 The thickness of the water layer is m; r is (r) 1 The sum of the radius of the circular hole air layer and the thickness of the oil layer is m; t is t 2 The thickness of the oil layer is m; r is (r) 2 Is the thickness radius of the round hole air layer, m.
Step 2, respectively solving the conductivity of each component of the two expanded equations simultaneously, and correcting the cementation index, the correction coefficient of the oil phase conductivity and the conductivity of clay;
the conductivity of each component of the two equations of the formula (6) and the formula (7) is solved simultaneously, and the conductivity is specifically shown as the formula (10) -formula (12):
φ m S w n σ w ＝φT w σ w (10)
φ m S w n α s σ o ＝φT o σ o (11)
solving the three equations to obtain corrected cementation indexes respectivelyCorrection coefficient of corrected oil phase conductivity +.>And conductivity of the modified clay->Specifically, the method is represented by the following formula (13) -formula (15):
and 3, obtaining a primary improved Rhoades capillary bundle model and a primary improved Waxman-Smits parallel model according to the corrected parameters.
By bringing the above correction parameters into the formulas (6) to (7), respectively, the CO for the clay-rich reservoir is finally obtained 2 Improved model of reservoir oil saturation change, namelyM carried into formula (7) will +.>Alpha carried into formula (7) s Will->Sigma brought into (6) s A primary modified Rhoades capillary bundle model and a primary modified Waxman-Smits parallel model are obtained, and the specific expression is formula (16) -formula (17):
and 4, obtaining a primary improved Rhoades capillary bundle model and a primary improved Waxman-Smits parallel model according to the fitting relation of the transmission factor and the saturation.
Saturation of the water and oil phases in the pores is shown in expressions (18) - (19):
wherein S is w Represents water saturation; s is S o Is oil saturation; t is t 3 Is CO 2 The thickness of the gas layer, m. Due to t 1 +t 2 +t 3 Is the general thickness of the throat and is a constant. Therefore, t 3 Can be made of t 1 And t 2 And (3) representing.
Comparing expressions (8) to (9) and expressions (18) to (19) shows that the transmission factor is the same as the independent variable of the saturation expression. To further express the relationship between the transmission factor and the saturation, the modified water-oil two-phase transmission factor and the saturation of water and oil are fitted to be linear, and the specific expression is shown in formulas (20) - (21):
T w ～aS w (t 1 ,t 2 ,r 1 ,L) (20)
T o ～bS o (t 1 ,t 2 ,r 1 ,L) (21)
wherein a is a fitting coefficient of water saturation, and b is a fitting coefficient of oil saturation;
substituting the modified water-oil two-phase transmission factor and saturation fitting expression (20) -expression (21) into expression (16) -expression (17) to finally obtain a secondary modified Rhoades capillary bundle model and a secondary modified Waxman-Smits parallel model, wherein the specific expressions are (22) - (23):
step 5, calculating to obtain the CO in the clay-rich hypotonic oil reservoir according to the secondarily improved Rhoades capillary bundle model and the secondarily improved Waxman-Smits parallel model 2 Fluid saturation. The method comprises the following steps: two-shot modified Rhoades capillary bundle model (22) and two-shot modified Waxman-Smits parallel model (23) to obtain CO 2 The saturation calculation formula of (2) is shown in formula (24):
wherein,representing CO 2 Is a saturation value of (a).
In order to demonstrate the feasibility and superiority of the present invention, the following comparative experiments were performed.
Experiment 1: comparing 5 different conductivity models;
in experiment 1, the porosity Φ=0.3, m=2, n=1.5, q was set v ＝9.7435mmol·cm -3 ，σ w Let-down reservoir water saturation S =20s/m w =1. The 5 conductivity models compared were the modified Rhoades capillary bundle model, the modified Waxman-Smits parallel model, the Archie model and the dihydrate model, respectively. The expression of the specific double water model is shown in the formula (25) -formula (27):
v Q ＝0.1α (27)
wherein,calculating the total conductivity of the rock for the double water model, S/m; v Q Cm as the amount of water associated with the unit clay cation 3 ·mmol -1 ；σ cw . The clay is given water conductivity, S/m. Here, in the double water model, β=3.05, α=1.
The final calculation results of experiment 1 are shown in fig. 3, and it can be seen from fig. 3 that the conductivity of the clay-added conductivity model is considered to be greater than that of the Archie model. By correcting the cementing index, the conductivity model corrected in experiment 1 is closer to the calculation result of the double water model considering the water conductivity of the movable stratum and the clay stratum, and the accuracy of the model is verified.
Experiment 2: for CO 2 And (3) carrying out saturation inversion calculation on the data of the sealed site, and simultaneously adopting a modified Waxman-Smits parallel model and an Archie model to invert saturation changes of different depths and the saturation of nuclear magnetic resonance logging for comparison. The porosity phi=0.3, m=2, n=1.5, q was set in experiment 2 v ＝9.7435mmol·cm -3 ，σ w ＝27.027S/m。
FIGS. 4 and 5 calculate CO for the Archie model and the modified Waxman-Smits parallel model, respectively 2 And comparing the relation between the saturation and the nuclear magnetic logging saturation. The relative error of the Archie model in the high clay-containing reservoir was 113.57% and the modified Waxman-Smits parallel model in the high clay-containing reservoir was 5.44%.
It should be understood that the above description is not intended to limit the invention to the particular embodiments disclosed, but to limit the invention to the particular embodiments disclosed, and that the invention is not limited to the particular embodiments disclosed, but is intended to cover modifications, adaptations, additions and alternatives falling within the spirit and scope of the invention.
Claims (6)
1. CO for clay-rich hypotonic oil reservoir 2 The saturation calculating method is characterized by comprising the following steps of:
step 1, respectively expanding a Rhoades capillary tube bundle model and a Waxman-Smits parallel conductivity model into a conductivity equation considering the influence of multiphase fluid and clay effect;
step 2, respectively solving the conductivity of each component of the two expanded equations simultaneously, and correcting parameters; parameters include cementation index, correction coefficient of oil phase conductivity and clay conductivity;
step 3, obtaining a primary improved Rhoades capillary bundle model and a primary improved Waxman-Smits parallel model according to the corrected parameters;
step 4, obtaining a secondarily improved Rhoades capillary bundle model and a secondarily improved Waxman-Smits parallel model according to the fitting relation between the transmission factor and the saturation;
step 5, calculating to obtain the CO in the clay-rich hypotonic oil reservoir according to the secondarily improved Rhoades capillary bundle model and the secondarily improved Waxman-Smits parallel model 2 Fluid saturation.
2. CO for clay-rich hypotonic reservoirs according to claim 1 2 The saturation calculating method is characterized in that the specific process of the step 1 is as follows:
the Rhoades capillary bundle model and the Waxman-Smits parallel conductivity model are shown in the formula (2) and the formula (3), respectively:
σ tr ＝σ w φT+σ s (2)
wherein sigma tr The total conductivity of the Rhoades capillary bundle model; sigma (sigma) tw The total conductivity of the parallel conductivity model of Waxman-Smits; sigma (sigma) w Indicating the conductivity of formation water; phi represents porosity; t represents a transmission factor; sigma (sigma) s Represents the electrical conductivity of the clay; s is S w Represents water saturation; b represents cation average mobility; q (Q) v Represents the volume concentration of clay mineral exchange cations; m and n represent the bond index and the saturation index, respectively;
b and Q in a Waxman-Smits parallel conductivity model v The expression of (a) is as shown in the formula (4) -formula (5):
wherein CEC is rock cation exchange capacity; ρ G Is the average particle density of the rock;
the equations (2) and (3) are extended to conductivity equations considering the influence of multiphase fluid and clay effect, respectively, and are expressed as the equations (6) and (7):
σ trm ＝σ w φT w +σ o φT o +σ s (6)
wherein sigma trm Gross resistivity of the capillary bundle model affected by multiphase fluid and clay effects; sigma (sigma) twm The total conductivity of the parallel conductivity model to account for multiphase fluid and clay effects; sigma (sigma) o Representing the conductivity of the low resistivity oil phase; alpha s Is a correction coefficient of oil phase conductivity; t (T) w Representing the modified aqueous phase transport factor, T o The modified oil phase transmission factor is represented by the following expressions (8) - (9):
wherein L is the length of the straight line segment of the capillary; t is t 1 Is the thickness of the water layer; r is (r) 1 The sum of the radius of the circular hole air layer and the thickness of the oil layer; t is t 2 Is the thickness of the oil layer; r is (r) 2 Is the thickness radius of the round hole air layer.
3. CO for clay-rich hypotonic reservoirs according to claim 2 2 The saturation calculating method is characterized in that the specific process of the step 2 is as follows:
the conductivity of each component of the two equations of the formula (6) and the formula (7) is solved simultaneously, and the conductivity is specifically shown as the formula (10) -formula (12):
φ m S w n σ w ＝φT w σ w (10)
φ m S w n α s σ o ＝φT o σ o (11)
to the three equationsSolving the rows to obtain a corrected cementation index m and a corrected coefficient of oil phase conductivity respectivelyAnd conductivity of the modified clay->Specifically, the method is represented by the following formula (13) -formula (15):
4. a CO according to claim 3 for a clay-rich hypotonic reservoir 2 The saturation calculating method is characterized in that the specific process of the step 3 is as follows:
will beM, which is taken into formula (7), will +.>Alpha, which is carried into equation (7) s Will->Sigma brought into formula (6) s Finally, a primary improved Rhoades capillary bundle model and a primary improved Waxman-Smits parallel model are obtained, wherein the specific expression is (16) -formula (17):
5. the CO for a clay-rich hypotonic reservoir of claim 4 2 The saturation calculating method is characterized in that the specific process of the step 4 is as follows:
saturation of the water and oil phases in the pores is shown in the expression (18) -formula (19):
wherein t is 3 Is CO 2 The thickness of the gas layer; s is S w Represents water saturation; s is S o Is oil saturation;
and (3) performing relation fitting on the corrected water and oil two-phase transmission factors and the water and oil saturation to obtain a linear relation, wherein the specific expression is shown in the formula (20) -formula (21):
T w ～aS w (t 1 ,t 2 ,r 1 ,L)(20)T o ～bS o (t 1 ,t 2 ,r 1 l) (21) wherein a is a fitting coefficient for water saturation and b is a fitting coefficient for oil saturation;
substituting the modified water-oil two-phase transmission factor and saturation fitting expression (20) -expression (21) into expression (16) -expression (17) to finally obtain a secondarily modified Rhoades capillary tube bundle model and a secondarily modified Waxman-Smits parallel model, wherein the specific expression is (22) -expression (23):
6. the CO for a clay-rich hypotonic reservoir of claim 5 2 The saturation calculating method is characterized in that the specific process of the step 5 is as follows:
two-shot modified Rhoades capillary bundle model (22) and two-shot modified Waxman-Smits parallel model (23) to obtain CO 2 As shown in formula (24),
wherein,representing CO 2 Is a saturation value of (a).
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| GB0525468D0 (en) * | 2004-12-20 | 2006-01-25 | Schlumberger Holdings | Method of evaluating fluid saturation characteristics in a geological formation |
| CN102434152A (en) * | 2011-12-05 | 2012-05-02 | 中国石油天然气股份有限公司 | Method for calculating oil saturation of reservoir |
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| GB0525468D0 (en) * | 2004-12-20 | 2006-01-25 | Schlumberger Holdings | Method of evaluating fluid saturation characteristics in a geological formation |
| CN102434152A (en) * | 2011-12-05 | 2012-05-02 | 中国石油天然气股份有限公司 | Method for calculating oil saturation of reservoir |
| CN111929219A (en) * | 2020-08-12 | 2020-11-13 | 西南石油大学 | Shale oil reservoir oil-water two-phase relative permeability calculation method |
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