Method for judging and predicting water content rising rule of water-drive sandstone reservoir

Abstract

The invention provides a method for judging and predicting the water content rise rule of a water-drive sandstone reservoir. The method mainly solves the problems that an existing method applying a water-drive curve and statistical experience is poor in adaptability, single and large in prediction error. The method is characterized by comprising the following steps: S1, judging dynamic and static parameters influencing a water content rise rule type, and judging the water content rise rule type according to the determined dynamic and static parameters; and S2, establishing a water content rise prediction method by dynamically combining geological factors and development so as to accurately control the water content rise change trend of the sandstone reservoir in a water injection development mode. According to the method for judging and predicting the water content rise rule of the water-drive sandstone reservoir, on the basis of establishing and judging the water content rise change rule of the water-drive sandstone reservoir from geological factors, an improved water content prediction differential method is further dynamically established on the basis of a mine field, and the method has certain universality and is high in prediction precision; and the method is suitable for water-injection development of sandstone reservoirs of different geological types and different development stages.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploration and development, and in particular to a method for determining and predicting the water content rise law of a water-driven sandstone reservoir under a water injection development mode. Background Art

[0002] The law of water cut rise is the most basic and important development indicator law of water-flooding oilfields. In general, the law of water cut rise in water-flooding oilfields determines the law of production decline, and the rate of liquid production is also determined by the law of water cut rise. It is necessary to study and master the law of water cut change in oilfields and take timely measures to control the rate of water cut rise in order to improve the recovery rate of water-flooding oilfields and improve the effect of water-flooding development. There are relatively many research methods and results on the law of water cut rise. In practice, the four water drive characteristic curves A, B, C and D recommended by China National Petroleum Corporation are generally used in mines. The prerequisite for the application of these four water drive curves is that the water drive curves have straight line segments. However, most of the medium and high permeability sandstone reservoirs have entered the stage of extremely high water content (water content greater than 90%), and the water drive curve is no longer applicable due to the downward bending phenomenon; while the low and ultra-low permeability sandstone oil fields have the characteristics of multiple reservoir types, poor reservoir properties, and complex geological conditions. The oil and water movement law and oil and water dynamic distribution after water injection development are becoming increasingly complex, which is reflected in the development indicators. The water content increase law of different blocks shows different forms. From the perspective of the curve shape of the relationship between water content and recovery degree, it can generally be divided into five typical water content increase modes: convex, convex-S type, S type, concave-S type and concave type. Especially for low, ultra-low permeability oil fields and ultra-high water content oil fields, in the prediction of water content increase indicators, water drive curves and statistical empirical methods are mainly used, which have problems such as poor adaptability and single method, and large prediction error. Therefore, it is necessary to start from geological factors and establish a water content index prediction method suitable for different types of sandstone reservoirs and different development stages on the basis of establishing the law of water content increase in water-driven sandstone reservoirs. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the problems of poor adaptability, singleness and large prediction error of the existing applied water drive curves and statistical empirical methods in the background technology, and to provide a method for determining and predicting the law of water content rise in water drive sandstone oil reservoirs. The method for determining and predicting the law of water content rise in water drive sandstone oil reservoirs, based on geological factors, establishes an improved water content prediction differential method based on mine field dynamics, has certain universality, small prediction error and high accuracy, and can be applied to water injection development of sandstone oil reservoirs of different geological types and different development stages.

[0004] The present invention solves the problem through the following technical solution: The method for determining and predicting the water content increase law of water-driven sandstone reservoirs comprises the following steps:

[0005] S1. Determine the dynamic and static parameters that affect the water content rising law type, and determine the water content rising law type based on the determined dynamic and static parameters;

[0006] S2. Based on the determined water-cut rising law type, geological factors are combined with development dynamics to establish a water-cut rising prediction method to accurately control the water-cut rising trend of sandstone reservoirs under water injection development.

[0007] Furthermore, the method of determining the dynamic and static parameters that affect the water content rise regularity type in step S1 includes the following steps:

[0008] S11. Derivation based on the oil-water seepage characteristic equation: For the relative permeability curves of oil and water, the expression of Willhite (1986) which has been tested in the field is selected:

[0009]

[0010]

[0011] in:

[0012] Where: C o - Oil phase index, f; C w - water phase index, f;

[0013] S wi - Irreducible water saturation, f; S or - residual oil saturation, f;

[0014] K rw - relative permeability of water phase, f; K ro - oil phase relative permeability, f;

[0015] K rw (S or ) - Relative permeability of residual oil to water phase at saturation, f;

[0016] K ro (S wi ) – relative permeability of oil phase at irreducible water saturation, f;

[0017] S w - Average water saturation, f; S wd - normalized water saturation, f;

[0018] S12. According to the oil-water two-phase flow split equation and mobility ratio definition commonly used in reservoir engineering, the two relative permeability curve expressions of oil and water (Formula 1, Formula 2) are substituted into the flow split equation (Formula 4), and the water cut expression (Formula 6) can be obtained by further deducing the mobility ratio relationship (Formula 5):

[0019]

[0020]

[0021] Where: f w - moisture content, f; μ w - Oil phase viscosity, cP; μ o - Viscosity of water phase, cP; M - Mobility ratio, f;

[0022]

[0023] According to S wd Definition, S wd In fact, it is equivalent to the recovery degree of movable oil, and formula (5) can be rewritten as:

[0024]

[0025] Therefore, the above formula (6) can be rewritten as:

[0026]

[0027] According to the definition of water-oil ratio, the above formula (8) can be further expressed as:

[0028]

[0029] Where: R - recovery degree, f;

[0030] WOR - water-oil ratio, f;

[0031] S13, assuming M = 1, C w =C o =1, then the above formula (9) is further simplified to:

[0032] f w =R

[0033] Under ideal conditions, the relationship curve between water content and recovery degree is a straight line passing through the origin with a slope of 1.

[0034] Furthermore, through the derivation of equations (8) and (9), it can be seen that the main factors affecting the change of water-oil ratio or water content are water-oil mobility ratio, water phase index and oil phase index.

[0035] Furthermore, the method of determining the type of water content rise law based on dynamic and static parameters in S1 includes:

[0036] For different types of water-driven reservoirs, the greater the mobility ratio, the smaller the water phase index, and the greater the oil phase index, the more the curve relationship between water cut and recovery degree tends to be convex; conversely, the smaller the mobility ratio, the greater the water phase index, and the smaller the oil phase index, the more the curve relationship between water cut and recovery degree tends to be concave;

[0037] The oil phase and water phase index are comprehensive indicators that reflect the pore structure characteristics and wettability of the reservoir. The larger the difference or ratio of the oil phase and water phase index, the more convex the water content and recovery degree curve becomes, which plays a strengthening and promoting role; conversely, the smaller the difference or ratio of the oil phase and water phase index, the more concave the water content and recovery degree curve becomes.

[0038] Furthermore, the S2 establishes a water cut rise prediction method based on the oil-water phase index, comprising the following steps:

[0039] S21, establishing a water-oil ratio and water content differential prediction equation based on the oil-water phase index;

[0040] S22. Based on the mine dynamics, an improved water-oil ratio and water content differential prediction equation is established.

[0041] Furthermore, the method for establishing the water-oil ratio differential prediction equation based on the oil-water phase index in S21 is:

[0042] The relationship between water-oil ratio and recovery degree (9) is further transformed and arranged to obtain:

[0043] ln(WOR)=C w ln(MR)-C o ln(1-R) (10)

[0045] Differentiating formula (10) with respect to time t, we can obtain:

[0046]

[0047] in:

[0048]

[0049] According to the relationship between liquid production rate, oil production rate and water content:

[0050] v o =v L ×(1-f w ) (13)

[0051] Where: v o - oil production rate, f;

[0052] v L - Liquid collection speed, f.

[0053] Substituting equations (12) and (13) into (11) and further rearranging them, we can obtain the differential prediction equation of water-oil ratio based on the oil-water phase index:

[0054]

[0055] Furthermore, the method of improving the water-oil ratio differential prediction equation based on the mine dynamics in S22 is:

[0056] S31, water drive curve is deformed to further obtain the relationship between recovery degree and water content;

[0057] S32. The deformed water drive curve is combined with the water-oil ratio differential prediction equation based on the oil-water phase index to obtain an improved water-oil ratio differential prediction equation.

[0058] Furthermore, the water drive curve includes four water drive characteristic curves A, B, C and D.

[0059] Furthermore, the specific method of further obtaining the relationship between the recovery degree and the water content by deforming the two water drive curves of type A and type C is as follows:

[0060] The two types of water drive curves of type A and type C are expressed as equations (15) and (16):

[0061] lgW P =A1+B1·N P (15)

[0062]

[0063] Where: A1, B1—intercept and slope of type A water drive curve, f;

[0064] A2, B2—Intercept and slope of type C waterflooding curve, f;

[0065] The type A and type C water drive characteristic curves can be rewritten into the following relationship form:

[0066]

[0067]

[0068] Where: a1, b1—Type A water drive curve coefficients, f;

[0069] a2, b2—Type C water drive curve coefficients, f;

[0070] Substituting equations (17) and (18) into equation (14) and further rearranging them, we can obtain the differential prediction equation for the change of water-oil ratio:

[0071]

[0072]

[0073] The differential prediction equation of the water-oil ratio change, wherein the oil-water phase index reflects the influence of the geological factors of the reservoir on the full-cycle change trend of the water content increase law, and the water drive curve coefficient reflects the influence of the development factors on the stage change trend of the water content increase law.

[0074] Furthermore, the method of combining the deformed type A and type C water drive curves with the water-oil ratio differential prediction equation based on the oil-water phase index to obtain the improved water cut prediction differential equation is:

[0075] If the water content change trend is predicted, formula (9) is substituted into formula (19) to obtain formula (21); formula (9) is substituted into formula (20) to obtain formula (22), and the following further improved differential equation for water content prediction based on oil-water phase index is obtained:

[0076]

[0077]

[0078] Formulas (19) to (22) are water content prediction differential equations based on the improved dynamics of the mine. According to the phase permeability curve data, the oil phase index and water phase index (C w , C o ), the water drive curve coefficients (a, b) and the fluid production rate (v L ) and the current water content. Under the given corresponding time step conditions, these five indicators can be brought in to obtain the water content increase value under the current production status of the reservoir.

[0079] Compared with the above background technology, the present invention has the following beneficial effects:

[0080] The water-driven sandstone reservoir water-cut rising law determination and prediction method has the following three main features: First, the two parameters of oil-water phase index can fully consider the influence of reservoir geological factors on the full-cycle change of water-cut rising law; second, the two parameters of water-drive curve coefficient take into account the influence of development factors on the stage change trend of water-cut rising law; third, the two parameters of current water content and liquid production rate can fully consider the influence of current mining dynamics. By determining the six parameters in these three aspects and applying the established prediction method, the purpose of greatly improving the prediction accuracy of water cut or water-oil ratio can be achieved.

[0081] The method of the present invention has stronger adaptability. First, it can be used for medium-high permeability oil fields in the medium-low water content stage and the ultra-high water content stage, and will not show unsuitable phenomena such as "no straight segment" and "downward bend"; second, for low-permeability oil fields with complex geological conditions, multiple reservoir types and multiple water content rise types, the water content rise law type can be determined in the early stage of development; after entering the medium-high water content stage, the water content rise trend can be predicted more accurately, avoiding the problems of poor adaptability and singleness, large prediction error and other problems of its commonly used statistical empirical prediction method. Starting from geological factors, the method of the present invention establishes an improved water content prediction differential method based on the dynamics of the mine field on the basis of establishing the law of water content rise changes in water-driven sandstone reservoirs, and has certain universality, small prediction error and high accuracy. It can be applied to water injection development of sandstone reservoirs of different geological types and different development stages. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 The relationship curve between water content and recovery degree under different mobility ratio changes of the present invention (the oil-water phase index remains unchanged);

[0083] Figure 2 The relationship curve between water content and recovery degree under different oil-water phase indices of the present invention (the mobility ratio remains unchanged);

[0084] Figure 3 This is a fitting diagram of the water phase index of an embodiment of the present invention;

[0085] Figure 4 This is the oil phase index fitting diagram of the embodiment of the present invention;

[0086] Figure 5 This is the relationship curve between water content and recovery degree of apricot zone 7 in the embodiment of the present invention;

[0087] Figure 6 This is the type A water flooding characteristic curve of the Xing 7 area in the embodiment of the present invention;

[0088] Figure 7 This is the fitting curve of water content and recovery degree of apricot zone 7 in the embodiment of the present invention. Specific implementation method:

[0089] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0090] The present invention discloses a method for determining and predicting the water-cut rising law of water-driven sandstone reservoirs. The method determines the type of water-cut rising law based on the oil-water phase index characteristics of the phase permeability curve, and establishes an index prediction method under different types of water-cut rising laws in conjunction with the water-driven curve, thereby achieving an organic combination of geological factors and development dynamics, improving the accuracy of water-cut rising prediction, and providing a scientific method for accurately controlling the index change trend of oil fields, and providing a scientific and reliable technical basis for production planning and decision-making deployment. The specific contents are as follows:

[0091] 1. Determine the water content rise pattern type of water-driven sandstone reservoirs based on mobility ratio and oil-water phase index

[0092] Relative permeability curve is an indispensable and important data in oilfield development calculation, dynamic analysis, determination of oil, gas and water saturation distribution in reservoirs, determination of reservoir rock wettability, preparation of oilfield development plan, prediction of oilfield development index, numerical simulation of reservoirs and theoretical analysis of reservoir engineering. It is generally believed that the main geological factor affecting the shape of water-cut rise curve is water-oil viscosity ratio / mobility ratio. Different types of reservoirs have different expressions of water-oil viscosity ratio / mobility ratio, and the water-cut change forms presented are different. This understanding has been widely recognized and applied to medium- and high-permeability sandstone water-driven oil reservoirs. However, for low-permeability oil fields, the law of oil-water movement is also affected by factors such as wettability and pore structure. Low-permeability oil reservoirs are more heterogeneous, so the shape of their relative permeability curves is more complex and diverse, and their water-cut rise law does not fully conform to this understanding. In order to obtain a universal method for determining the law of water-cut rise in water-driven sandstone reservoirs, it is derived based on the oil-water seepage characteristic equation. Among the various expressions of the relative permeability curves of oil and water, the one that has been tested and widely used in the field is the expression of Willhite (1986):

[0093]

[0094]

[0095] in:

[0096] Where: C o - Oil phase index, f; C w - water phase index, f;

[0097] S wi - Irreducible water saturation, f; S or - residual oil saturation, f;

[0098] K rw (- relative permeability of water phase, f; K ro (-Oil phase relative permeability, f.

[0099] K rw (S or ) - Relative permeability of residual oil to water phase at saturation, f;

[0100] K ro (S wi ) – relative permeability of oil phase at irreducible water saturation, f;

[0101] S w - Average water saturation, f; S wd- normalized water saturation, f;

[0102] According to the oil-water two-phase flow equation commonly used in reservoir engineering (MCLeverett, 1941) and the mobility ratio definition:

[0103]

[0104]

[0105] Where: f w - moisture content, f; μ w - Oil phase viscosity, cP; μ o - Viscosity of water phase, cP; M - Mobility ratio, f.

[0106] Substituting the two relative permeability curve expressions of oil and water into the fractional flow equation and further deducing through the mobility ratio relationship, the expression of water cut can be obtained:

[0107]

[0108] According to S wd Definition, S wd In fact, it is equivalent to the degree of recovery of movable oil:

[0109]

[0110] Where: R - recovery degree, f.

[0111] Therefore, the above formula can be rewritten as:

[0112]

[0113] According to the definition of water-oil ratio, the above formula can be further expressed as:

[0114]

[0115] Where: WOR - water-oil ratio, f.

[0116] Assume M = 1, C w =C o =1, the above formula is further simplified to:

[0117] f w =R

[0118] Under ideal conditions, the relationship curve between water content and recovery degree is a straight line passing through the origin with a slope of 1.

[0119] From the above formula, we can know that the main factors affecting the change of water-oil ratio or water cut are water-oil mobility ratio, water phase index and oil phase index. For different types of water-drive reservoirs, the larger the mobility ratio, the smaller the water phase index and the larger the oil phase index, the more the curve relationship between water cut and recovery degree tends to be convex; on the contrary, the smaller the mobility ratio, the larger the water phase index and the smaller the oil phase index, the more the curve relationship between water cut and recovery degree tends to be concave (such as Figure 1 As shown). Among them, the mobility ratio plays an important weighting role and is therefore the main factor affecting the law of water content increase. The oil phase and water phase index are comprehensive indicators that reflect the pore structure characteristics and wettability of the reservoir. Generally, the water phase index is between 0.5 and 2.0, and the oil phase index is between 1.0 and 3.5. The greater the difference or ratio between the oil phase and water phase indexes, the more convex the water content and recovery degree curve becomes, which plays a strengthening and promoting role; on the contrary, the smaller the difference or ratio between the oil phase and water phase indexes, the more concave the water content and recovery degree curve becomes (such as Figure 2 As shown in the figure above, the above formula is universal, so the water content increase law type of water-driven sandstone reservoir can be determined according to the mobility ratio and oil-water phase index, which provides a reliable technical basis for grasping the dynamic change trend of water content in the whole cycle and formulating corresponding adjustment countermeasures and production strategies.

[0120] 2. Establishing a method for predicting water cut rise based on the oil-water phase index

[0121] According to the analysis and summary of the research results on the development law of dynamic indicators such as the increase of water content in oil fields, there are generally two understandings: First, static indicators determine the pattern, that is, the geological factors / innate conditions of the reservoir determine the change pattern of the dynamic indicators throughout the process / life cycle. As long as the displacement method remains unchanged, the indicator change pattern is not controlled by development factors such as well type, well spacing and measures, which is suitable for grasping the indicator trend in the long term and macro-overall; second, dynamic indicators determine the trend, which refers to the degree of influence of development factors / acquired mining conditions on the stage trend of the indicator law. Although development factors do not change the indicator change pattern, they will affect the stage change trend (the curve of a certain stage will shift), which is suitable for short-term indicator prediction. Therefore, it is necessary to establish a water-cut increase prediction method that combines geological factors with development dynamics to accurately control the water-cut increase change trend of sandstone reservoirs under water injection development.

[0122] 1. Establish the water-oil ratio and water content differential prediction equation based on the oil-water phase index

[0123] Further deformation and arrangement of formula (9) yields:

[0124] ln(WOR)=C w ln(MR)-C o ln(1-R) ​​(10)

[0125] Differentiating the above formula with respect to time t, we can obtain:

[0126]

[0127] In general, if time t is taken as annual or monthly, then:

[0128]

[0129] Where: v o - Oil production rate, f.

[0130] According to the relationship between liquid production rate, oil production rate and water content:

[0131] v o =v L ×(1-f w ) (13)

[0133] Where: v L - Liquid collection speed, f.

[0134] Substituting equations (12) and (13) into (11) and further rearranging them, we can obtain:

[0135]

[0136] Formula (14) is the differential prediction equation of water-oil ratio based on the oil-water phase index.

[0137] 2. Improve the water-oil ratio and water content differential prediction equations based on mine dynamics;

[0138] 21. After the water drive curve is deformed, the relationship between the recovery degree and the water-oil ratio is further obtained (Equation 17, Equation 18). The deformed water drive curve (Equation 17, Equation 18) is combined with the water-oil ratio differential prediction equation based on the oil-water phase index (Equation 14), and the improved water-oil ratio prediction differential equations based on the mine dynamics are obtained (Equation 19, Equation 20);

[0139] The water drive curves include four water drive characteristic curves: A, B, C and D.

[0140] The water drive curve series equations are the production rules generally followed by water injection development oil fields after entering the medium and high water content period. Among them, the type A and type C water drive curves have good adaptability to different types of water drive sandstone reservoirs and have been widely used, such as equations (15) and (16).

[0141] lgW P =A1+B1·N P (15)

[0142]

[0143] Where: A1, B1—intercept and slope of type A water drive curve, f;

[0144] A2, B2—Intercept and slope of type C waterflooding curve, f.

[0145] The type A and type C water drive characteristic curves can be rewritten into the following relationship form:

[0146]

[0147]

[0148] Where: a1, b1—Type A water drive curve coefficients, f;

[0149] a2, b2—Type C water drive curve coefficients, f.

[0150] Substituting equations (17) and (18) into (14) and further rearranging them, we can obtain:

[0151]

[0152]

[0153] Formulas (19) and (20) are differential prediction equations for the change of water-oil ratio, where the oil-water phase index reflects the influence of geological factors of the reservoir on the full-cycle change trend of the water-cut rise law, and the water drive curve coefficient reflects the influence of development factors on the stage change trend of the water-cut rise law. The established water-oil ratio prediction method can fully consider the comprehensive influence of geological factors and development dynamics, and accurately predict the water-cut rise trend of different types of sandstone reservoirs at different water-cut stages.

[0154] Similarly, if the water content change trend is predicted, the above formulas 9, 19, and 20 can be further rewritten as:

[0155]

[0156]

[0157] Equations (21) and (22) are the water content differential prediction equations based on the oil-water phase index.

[0158] Example 1

[0159] Taking the application in the water-flooding Xing 7 block in Changyuan, Daqing as an example, a method for determining and predicting the water content rise law of a water-flooding sandstone reservoir of the present invention is specifically described, comprising the following steps:

[0160] (I) Predicting the type of water-cut rise in sandstone reservoirs

[0161] 1) Blockchain status

[0162] The Daqing Changyuan water-driven Xing 7 block is a medium-to-high permeability sandstone water-driven oil reservoir. The main target layers are the Sartu and Putaohua oil layers with serious heterogeneity. The effective porosity is 28.3%, the effective permeability is 295.2mD, the crude oil saturation is 66.4%, the water-oil mobility ratio is 22.5, and the current water content is as high as over 95%.

[0163] 2) Calculate the oil phase and water phase index

[0164] Generally, the linear regression method is used to determine the oil phase and water phase index. First, the formulas (1) and (2) are transformed to obtain the formulas (23) and (24), and then regression fitting is performed. The slope of the curve is the oil phase and water phase index.

[0165] lgk rw =a+C w lgS wd (twenty three)

[0167] lgk ro =b+C o lg(1-S wd ) (twenty four)

[0169] The typical relative permeability curve data of this block (as shown in Table 1) were selected and processed for fitting. The water phase index fitting diagram is shown in Figure 3 ; Oil phase index fitting diagram see Figure 4 The oil phase and water phase indices were 2.22 and 1.28, respectively, and the correlation coefficients were both higher than 0.99.

[0170] 3) Determination of water content rise type

[0171] According to the method for determining the type of water cut rise, the water-oil mobility of this block is high, and the oil phase index is higher than the water phase index, so the water cut rise curve of this block should show a convex trend. Figure 5 The changes in water content and recovery degree of Xing7 area are shown in Table 2; from the actual statistical data of the block (Table 2, Figure 5 ) shows a convex feature with a large water content rising in the early stage and a slow water content rising in the later stage. The theoretical understanding is consistent with the actual changes.

[0172] (2) Prediction of the water content increase trend in high permeability sandstone reservoirs during the ultra-high water content period

[0173] 1) The original water drive curve method is no longer applicable

[0174] For sandstone reservoirs with extremely high water content, the water drive curve shows a downward bend phenomenon, and the original water drive curve method is no longer suitable. The water drive curve is made by statistically analyzing the actual data of the block (such as Figure 6 As shown in the figure, it can be seen that the downward bending phenomenon has occurred. If the prediction is continued, a large error will occur.

[0175] 2) Application of improved water content differential prediction equation for prediction

[0176] Table 2 is the dynamic data of the mine. The fitting curve of water content and extraction degree after deformation is shown in Table 2 according to formula (17). Figure 7 ; First, the water drive curve coefficient after deformation is fitted according to formula (17) from Table 2 ( Figure 7 ), a1 = 0.4045, b1 = 3.7973, the correlation coefficient is higher than 0.99; then according to the mine dynamics, the liquid production rate and the current water content can be obtained, and substituted into formula (21) for prediction. Table 3 is a comparison table of the prediction results of the conventional water drive curve and the new prediction method of the present invention; It can be seen from Table 3 that the comparison with the conventional water drive curve prediction results shows that the absolute error of the water content prediction of the water drive curve method is about 0.01% to 0.02%, while the prediction error of the new prediction method is controlled to about 0.001% to 0.003%, and the prediction accuracy of the new method has been greatly improved.

[0177] Table 1 Typical phase infiltration curves of apricot zone 7

[0178] Serial number Sw(%) 1-sw Kro(%) Krw(%) Fw(%) lg(swd) LqCy swd lg(1-swd) lgKro 1 0.3585 0.6415 1.0000 0.0000 0.0000 / / 0.000 0.000 0.000 2 0.3775 0.6225 0.7842 0.0108 0.1759 -1.255 -1.967 0.056 -0.025 -0.106 3 0.3965 0.6035 0.6408 0.0205 0.3315 -0.954 -1.688 0.111 -0.051 -0.193 4 0.4155 0.5845 0.5273 0.0310 0.4768 -0.778 -1.509 0.167 -0.079 -0.278 5 0.4345 0.5655 0.4329 0.0428 0.6051 -0.653 -1.369 0.222 -0.109 -0.364 6 0.4535 0.5465 0.3546 0.0553 0.7074 -0.556 -1.257 0.278 -0.141 -0.450 7 0.4725 0.5275 0.2887 0.0688 0.7870 -0.477 -1.162 0.333 -0.176 -0.540 8 0.4915 0.5085 0.2312 0.0833 0.8481 -0.410 -1.079 0.389 -0.214 -0.636 9 0.5105 0.4895 0.1836 0.0996 0.8937 -0.352 -1.002 0.444 -0.255 -0.736 10 0.5295 0.4705 0.1437 0.1177 0.9270 -0.301 -0.929 0.500 -0.301 -0.843 11 0.5485 0.4515 0.1101 0.1374 0.9508 -0.255 -0.862 0.556 -0.352 -0.958 12 0.5675 0.4325 0.0824 0.1593 0.9677 -0.214 -0.798 0.611 -0.410 -1.084 13 0.5865 0.4135 0.0607 0.1834 0.9791 -0.176 -0.737 0.667 -0.477 -1.217 14 0.6055 0.3945 0.0436 0.2091 0.9867 -0.141 -0.680 0.722 -0.556 -1.361 15 0.6245 0.3755 0.0307 0.2368 0.9917 -0.109 -0.626 0.778 -0.653 -1.513 16 0.6435 0.3565 0.0208 0.2672 0.9950 -0.079 -0.573 0.833 -0.778 -1.682 17 0.6625 0.3375 0.0133 0.3010 0.9972 -0.051 -0.521 0.889 -0.954 -1.876 18 0.6815 0.3185 0.0080 0.3375 0.9985 -0.025 -0.472 0.944 -1.255 -2.097

[0179] Table 2 Changes in water content and extraction rate in apricot zone 7

[0180] R,f fw,f R,f fw,f 0.0001 0.0000 0.5818 0.7577 0.0036 0.0000 0.5977 0.7677 0.0088 0.0000 0.6211 0.7805 0.0209 0.0105 0.6461 0.8004 0.0353 0.0493 0.6754 0.8105 0.0499 0.0774 0.7015 0.8411 0.0686 0.0824 0.7257 0.8654 0.0916 0.1426 0.7481 0.8812 0.1201 0.2115 0.7683 0.8935 0.1502 0.3035 0.7848 0.9043 0.1798 0.3867 0.7978 0.9103 0.2070 0.4443 0.8099 0.9144 0.2305 0.5273 0.8213 0.9181 0.2530 0.5933 0.8324 0.9210 0.2750 0.6580 0.8430 0.9276 0.2967 0.6975 0.8527 0.9310 0.3183 0.7089 0.8608 0.9361 0.3388 0.7165 0.8690 0.9373 0.3555 0.7096 0.8707 0.9444 0.3733 0.7229 0.8782 0.9407 0.3927 0.7376 0.8859 0.9410 0.4155 0.7375 0.8910 0.9436 0.4434 0.7386 0.8994 0.9438 0.4745 0.7361 0.9075 0.9468 0.5067 0.7388 0.9154 0.9499 0.5371 0.7492 0.9251 0.9521 0.5571 0.7552 0.9337 0.9543

[0181] Table 3 Comparison of water content prediction results in 7 apricot areas

[0182]

[0183] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Therefore, the content of the present invention is not limited to the examples listed, and any equivalent changes taken by ordinary technicians in the field of the present invention by reading the specification of the present invention to the technical solution of the present invention are all covered by the claims of the present invention.

Claims

1. A method for determining and predicting the water content increase law of a water-driven sandstone reservoir, characterized in that: The following steps are involved: S1. Determine the dynamic and static parameters that affect the water content rising law type, and determine the water content rising law type based on the determined dynamic and static parameters; S2. Based on the determined water-cut rising law type, geological factors are combined with development dynamics to establish a water-cut rising prediction method to accurately control the water-cut rising trend of sandstone reservoirs under water injection development.

2. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 1 is characterized by: The method of determining the dynamic and static parameters that affect the water content rise regularity type in step S1 comprises the following steps: S11. Derivation based on the oil-water seepage characteristic equation: For the two relative permeability curves of oil and water, the Willhite expression verified by the actual mine is selected: in: Where: C o - Oil phase index, f; C w - water phase index, f; S wi - bound water saturation, f; S or - residual oil saturation, f; K rw - relative permeability of water phase, f; K ro - oil phase relative permeability, f; K rw (S or ) - Relative permeability of residual oil to water phase at saturation, f; K ro (S wi ) – relative permeability of oil phase at irreducible water saturation, f; S w - Average water saturation, f; S wd - normalized water saturation, f; S12. According to the oil-water two-phase flow separation equation and mobility ratio definition commonly used in reservoir engineering, the two relative permeability curve expressions of oil and water are substituted into the flow separation equation, and the water content expression (6) can be further derived through the mobility ratio relationship: Where: f w - moisture content, f; μ w - Oil phase viscosity, cP; μ o - Viscosity of water phase, cP; M - Mobility ratio, f; According to S wd Definition, S wd In fact, it is equivalent to the recovery degree of movable oil. According to the calculation formula of recovery degree: Substituting formula (7) into formula (6), we can get: According to the definition of water-oil ratio, the above formula (8) can be further expressed as: Where: R - recovery degree, f; WOR - water-oil ratio, f; S13, assuming M = 1, C w =C o =1, then the above formula (9) is further simplified to: f w =R Under ideal conditions, the relationship curve between water content and recovery degree is a straight line passing through the origin with a slope of 1.

3. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 2 is characterized in that: From the derived water cut formula (8) and water-oil ratio formula (9), it can be seen that the main factors affecting the change of water-oil ratio or water cut are water-oil mobility ratio, water phase index and oil phase index.

4. The method for determining and predicting the water content increase law of water-flooded sandstone reservoirs according to claim 1 or 2, characterized in that: The method of determining the type of water content rise law based on dynamic and static parameters in S1 includes: For different types of water-driven reservoirs, the greater the mobility ratio, the smaller the water phase index, and the greater the oil phase index, the more the curve relationship between water cut and recovery degree tends to be convex; conversely, the smaller the mobility ratio, the greater the water phase index, and the smaller the oil phase index, the more the curve relationship between water cut and recovery degree tends to be concave; The oil phase and water phase index are comprehensive indicators that reflect the pore structure characteristics and wettability of the reservoir. The larger the difference or ratio of the oil phase and water phase index, the more convex the water content and recovery degree curve becomes, which plays a strengthening and promoting role; conversely, the smaller the difference or ratio of the oil phase and water phase index, the more concave the water content and recovery degree curve becomes.

5. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 1 or 2, characterized in that: The S2 establishes a water cut rise prediction method based on the oil-water phase index, comprising the following steps: S21, establishing a water-oil ratio and water content differential prediction equation based on the oil-water phase index; S22. Based on the mine dynamics, an improved water-oil ratio and water content differential prediction equation is established.

6. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 5, characterized in that: The method for establishing the water-oil ratio differential prediction equation based on the oil-water phase index in S21 is: The relationship between water-oil ratio and recovery degree R (9) is further transformed and arranged to obtain: ln(WOR)=C w ln(MR)-C o ln(1-R) (10) Differentiating formula (10) with respect to time, we can obtain: in: According to the relationship between liquid production rate, oil production rate and water content: v o =v L ×(1-f w ) (13) Where: v o - oil production rate, f; v L - Liquid collection speed, f. Substituting equations (12) and (13) into (11) and further rearranging them, we can obtain the differential prediction equation of water-oil ratio based on the oil-water phase index:

7. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 5, characterized in that: The method of improving the water-oil ratio differential prediction equation based on the mine dynamics in S22 is: S31, water drive curve is deformed to obtain the relationship between recovery degree and water content; S32. The deformed water drive curve is combined with the water-oil ratio differential prediction equation based on the oil-water phase index to obtain an improved water-oil ratio differential prediction equation.

8. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 7, characterized in that: The water drive curves include four water drive characteristic curves: A, B, C and D.

9. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 8, characterized in that: The specific method for further obtaining the relationship between the recovery degree and the water content after deformation of the two water drive curves of type A and type C is as follows: The two types of water drive curves of type A and type C are expressed as formula (15) and formula (16): lgW p =A1+B1·N p (15) Where: A1, B1—intercept and slope of type A water drive curve, f; A2, B2—Intercept and slope of type C waterflooding curve, f; The type A and type C water drive characteristic curves can be rewritten into the following relationship form: Where: a1, b1—Type A water drive curve coefficients, f; a2, b2—Type C water drive curve coefficients, f; Substituting equations (17) and (18) into equation (14) and further rearranging them, we can obtain the differential prediction equation for the change of water-oil ratio: The differential prediction equation of the water-oil ratio change, wherein the oil-water phase index reflects the influence of the geological factors of the reservoir on the full-cycle change trend of the water content increase law, and the water drive curve coefficient reflects the influence of the development factors on the stage change trend of the water content increase law.

10. The method for determining and predicting the water content increase rule of water-flooded sandstone reservoirs according to claim 5 or 9, characterized in that: The method of establishing the improved water content differential prediction equation based on the mine dynamics in step S22 is: The modified type A and type C water drive curves are combined with the water-oil ratio differential prediction equation based on the oil-water phase index to obtain the improved water cut differential prediction equation, which is: Substituting formula (9) into formula (19) yields formula (21); substituting formula (9) into formula (20) yields formula (22), and the following further improved differential equation for predicting water content based on the oil-water phase index is obtained:

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