Water drive control reserve calculation method and device for high-pressure capacity expansion water injection of oil reservoir

Abstract

The invention discloses a water drive control reserve calculation method and device for oil reservoir high-pressure dilatation water injection. The method comprises the steps that a relation curve between the water injection rate and the water injection pressure during formation water injection is monitored and drawn; when only a curve with a single slope K1 appears on the relation curve between the water injection rate and the water injection pressure, the water flooding control reserves are calculated through K1 and a crude oil compression coefficient; and when a plurality of curves of which the slopes are K1 to Kn sequentially appear on the relation curve between the water injection rate and the water injection pressure, calculating new water drive control reserves and newly added reserves according to the curve slopes K1 to Kn and the crude oil compression coefficient. According to the method, the equation is discretized according to the crude oil compressibility coefficient equation, the relation between the water flooding control reserves and the crude oil compressibility coefficient and the relation between the water flooding control reserves and the slope on the water injection rate-water injection pressure curve are obtained according to actual calculation requirements, and the water flooding reserves after high-pressure expansion water injection can be obtained. Meanwhile, the method solves the problem of calculation of newly added water drive reserves when the seepage barrier is broken through during high-pressure water injection.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir water injection methods, and in particular relates to a method and a device for calculating water drive controlled reserves for high pressure expansion water injection in oil reservoirs. Background Art

[0002] Due to its special accumulation mechanism, most of the development units of carbonate reservoirs are closed or weakly fixed in volume. Insufficient energy is the main factor affecting production capacity. In order to restore the production capacity of oil wells, water injection to supplement energy is generally adopted. However, conventional water injection is generally adopted for carbonate development at present, and the water injection pressure is generally controlled within 25Mpa. In some oil fields, water injection has become the main means of stabilizing the production of carbonate oil wells. The method of the present invention is an innovative method formed on the basis of considering the geological background of the reservoir, the well-reservoir relationship, and the fault-reservoir relationship. Under normal circumstances, the wellhead pressure will be higher than 25Mpa, and even 40Mpa is needed to break through the seepage barrier between unconnected or weakly connected reservoirs. The invention of this method provides a new method for increasing reserves and production in carbonate reservoirs during the high water content period, and provides a new means for the management of long-stopped inefficient wells.

[0003] The patent publication number is CN114482947A, and the patent name is a patent application for a method for implementing high-pressure water injection technology for carbonate fracture-cave oil reservoirs, including: analyzing the well-reservoir relationship of the current oil reservoir area, and / or the comparison results of static reserves and produced reserves, and / or the state of the current producing channel according to the static seismic data of the oil reservoir area to be constructed; determining the water injection method suitable for the current oil reservoir area according to the regional analysis results, and obtaining the construction parameters including the total water injection volume and / or the water injection displacement according to the construction principles corresponding to the water injection method, wherein the water injection method is selected from one of the bottom water-simulating high-pressure water injection technology for creating an artificial secondary bottom water level and the fracturing-simulating high-pressure water injection technology for establishing a reserve producing channel; using the construction parameters, according to the water injection method, high-pressure water injection operations are performed on the current oil reservoir area. This patent application can achieve the productivity growth of low-capacity wells or water injection failure wells, and meet the sustainable water injection development needs, but this patent application cannot solve the problem of calculating the newly added water drive reserves when the seepage barrier is opened during high-pressure water injection. Summary of the invention

[0004] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method and device for calculating the water-driven controlled reserves of high-pressure expansion water injection in oil reservoirs. Aiming at the problem of poor internal connectivity in multi-fracture carbonate rocks, through precise design, the seepage barriers between unconnected or weakly connected reservoirs are opened up, providing a new means for increasing reserves and production in the high water cut period.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for calculating the water flooding controlled reserves of an oil reservoir with high pressure expansion water injection comprises the following steps:

[0007] S1: Monitor and draw the relationship curve between injection volume and injection pressure during formation water injection;

[0008] S2: When only a single slope K1 curve appears on the relationship curve between water injection volume and water injection pressure, the water drive controlled reserves are calculated by K1 and the crude oil compressibility coefficient;

[0009] S3: When the relationship curve between injection volume and injection pressure has slopes from K1 to K n When there are multiple curves, the slope of the curve K1 to the slope of the curve K n and crude oil compression coefficient, calculate the new water drive controlled reserves and additional reserves.

[0010] Optionally, in step S2, the calculation method of the water flooding controlled reserves is as follows:

[0011] V0=1 / (C O *K1);

[0012] Where V0 is the waterflooding controlled reserves;

[0013] C O is the crude oil compressibility factor;

[0014] K1 is the slope of the curve.

[0015] Optionally, in step S3, the calculation formula of the new water flooding controlled reserves is V1=1 / (C0*K n ), the calculation formula for the newly added reserves is V2=1 / (C0*K n )-1 / (C O *K n-1 );

[0016] Where, V1 is the new waterflooding controlled reserves;

[0017] V2 is the newly added waterflooding controlled reserves;

[0018] C O is the crude oil compressibility factor;

[0019] K1, K n is the slope of the corresponding curve, where n>1.

[0020] Optionally, before injecting water into the formation in step S1, the following steps are included:

[0021] 1) Based on the field data, the liquid production at the wellhead when the unit formation pressure changes;

[0022] 2) Obtain the required formation pressure through well testing;

[0023] 3) Obtaining the formation pressure difference according to the required formation pressure and the original formation pressure;

[0024] 4) Multiply the formation pressure difference by the unit liquid production to obtain the required water injection volume, and inject water into the formation according to the required water injection volume.

[0025] Optionally, in step 2), the required formation pressure is calculated as: h =0.018H, where P h is the formation pressure; H is the formation depth.

[0026] Optionally, in step 2), the required formation pressure is calculated as: h =0.014H, where P h is the formation pressure, and H is the formation depth.

[0027] Optionally, before injecting water into the formation in step S1, the following steps are included:

[0028] Test and calculate the formation pressure P of the on-site wellbore before water injection i ;

[0029] Calculate the formation pressure P after water injection h =1.3P i ;

[0030] Calculate the required formation water injection volume W i =NB oi C o (P h -P i ), and according to the required water injection volume W i injecting water into the formation;

[0031] Where W i Fill the required amount of water;

[0032] B oi is the volume coefficient of the original crude oil;

[0033] C o is the crude oil compressibility factor;

[0034] P h is the required formation pressure;

[0035] P i is the formation pressure before water injection.

[0036] A device for calculating the water drive controlled reserves of high pressure expansion water injection in oil reservoirs, comprising:

[0037] Monitoring module, used to monitor and draw the relationship curve between injection volume and injection pressure during formation water injection;

[0038] The first processing module is used to calculate the water drive controlled reserves by using K1 and the crude oil compressibility coefficient when only a curve with a single slope K1 appears on the water injection volume-water injection pressure curve;

[0039] The second processing module is used to generate a water injection volume-water injection pressure curve with slopes from K1 to K1. n When there are multiple curves, the slope of the curve K1 to the slope of the curve K n and crude oil compression coefficient, calculate the new water drive controlled reserves and additional reserves.

[0040] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for calculating the water drive controlled reserves of the oil reservoir high pressure expansion water injection are implemented.

[0041] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for calculating the water drive controlled reserves of the oil reservoir high-pressure expansion water injection.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention discloses a method for calculating the water drive controlled reserves of high pressure expansion water injection in an oil reservoir, which enriches the principle of carbonate rock water injection, explores and establishes a systematic high pressure expansion water injection technology system. According to the crude oil compression coefficient equation of a constant volume reservoir, the present invention discretizes the equation, and according to the actual calculation needs, assumes that the volume of the injected water is unchanged, and can obtain the conclusion that the volume of the injected water is equal to the volume of the crude oil compressed in the reservoir. The above derivation process formula is sorted out to obtain the relationship between the water drive controlled reserves and the crude oil compression coefficient and the slope on the water injection volume-water injection pressure curve. According to these data, the water drive reserves after high pressure expansion water injection can be obtained. At the same time, the present invention solves the problem of calculating the newly added water drive reserves when the seepage barrier is opened during high pressure water injection. The successful application of the present invention provided by the present invention can provide an effective way for the treatment of failed and inefficient wells in the middle and late stages of carbonate rock water injection development in oil fields.

[0044] Furthermore, the present invention obtains the required water injection volume by multiplying the wellhead liquid production by the formation pressure difference when the unit formation pressure is changed. According to the pressure gradient method and the fracture closure pressure calculation formula, and based on empirical summary, an empirical coefficient for calculating the required formation pressure is given, which is easy to calculate and can meet actual production needs.

[0045] Furthermore, the present invention summarizes experience and provides that the formation pressure after water injection is 1.3 times the formation pressure before water injection, which is easy to calculate and can meet actual production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings:

[0047] Figure 1 It is a schematic diagram of the process of the present invention;

[0048] Figure 2 It is a conventional water injection indicator curve diagram;

[0049] Figure 3 This is a high-pressure expansion water injection indication curve diagram of the present invention;

[0050] Figure 4 This is a production curve diagram of Well A in an embodiment of the present invention;

[0051] Figure 5 This is the high-pressure water injection expansion water injection indicator curve of Well A in the embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0053] It should be understood by those skilled in the art that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0054] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0058] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The present application may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0059] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0060] The present invention is described in detail below with reference to the accompanying drawings.

[0061] like Figure 1 As shown, a method for calculating water drive controlled reserves for high pressure expansion water injection of an oil reservoir according to the present invention includes a method for calculating the required water injection volume before water injection and a method for calculating the water drive controlled reserves after water injection.

[0062] After determining the required water injection volume, water injection operation can be carried out. After water injection, water drive control reserves need to be calculated. Water drive reserves refer to the oil reserves in the wellbore driven by formation water and pushed into the pores of the reservoir. Usually, when crude oil is extracted from the oil layer, the formation water will move with it, and as the oil is extracted, the pressure and flow rate of the formation water will gradually decrease, which means that the driving effect of water will weaken.

[0063] Therefore, for some oil reservoirs with high water content in crude oil, their water drive reserves will gradually decrease as the production process proceeds. In general, water drive reserves are one of the important indicators to measure the development potential of oil fields.

[0064] The method for calculating the controlled reserves of water flooding after water flooding of a method for calculating the controlled reserves of water flooding for high pressure expansion water flooding of an oil reservoir according to the present invention can be calculated according to the following steps:

[0065] S1: Inject water into the formation, monitor and draw the relationship curve between injection volume and injection pressure;

[0066] S2: When only a single slope K1 curve appears on the water injection volume-water injection pressure curve, the K1 and crude oil compressibility coefficient C O Able to calculate water flooding controlled reserves V0;

[0067] S3: When the curve with slope K1 and the curve with slope K2 appear on the water injection volume-water injection pressure curve, the K1, K2 and crude oil compression coefficient C O The new water flooding controlled reserves V1 and the newly added reserves V2 can be calculated.

[0068] Among them, in step S1, the water injection volume is the horizontal axis and the water injection pressure is the vertical axis. By counting the water injection volume corresponding to the water injection pressure during the water injection process, the corresponding statistical points between the water injection volume and the water injection pressure can be obtained. By fitting multiple statistical points, a straight line of a linear equation can be obtained, such as Figure 2 As shown, by taking two points on the graph, we can calculate the slope K1 = (W2-W1) / (P2-P1).

[0069] If the water injection volume-water injection pressure curve always has a single slope, that is, Figure 2 The situation shown means that the seepage barrier in the formation was not broken through after water injection.

[0070] If two slopes K1 and K2 appear on the water injection volume-water injection pressure curve, that is, Figure 3 The situation shown means that the seepage barrier in the formation has been opened up after water injection.

[0071] Among them, in steps S2 and S3, the specific calculation method and principle of the water flooding controlled reserves V0 are as follows:

[0072] For a constant volume reservoir, the crude oil compressibility equation can be obtained:

[0073]

[0074] Where: C O is the crude oil compressibility factor;

[0075] V is the underground volume of crude oil in the reservoir, in units of 10 4 m 3 ;

[0076] P is the formation pressure, in MPa.

[0077] After discretizing equation (1), we can get:

[0078]

[0079] Where: P O is the formation pressure at the time of initial water injection, in MPa;

[0080] P i It is the formation pressure after water injection, in MPa.

[0081] When injecting water into a formation, assuming that the volume of injected water remains constant, the compressibility factor is approximately 1;

[0082] The volume of injected water is approximately equal to the volume of compressed crude oil in the reservoir, that is:

[0083] ΔW i =ΔV (3)

[0084] Arranging formula (3) and formula (2) yields:

[0085]

[0086] Assuming K = 1 / C0V, the formation pressure change can be expressed by the wellhead injection pressure change;

[0087] Then formula (5) can be rearranged as:

[0088] P=K×ΔW i +b (6)

[0089] Where, P is the injection pressure, in MPa;

[0090] b is the intercept, a constant.

[0091] Draw a curve of the relationship between the cumulative water injection volume and the injection pressure. The dynamic reserves after expansion water injection can be calculated using the slope of the curve and the crude oil compression coefficient, namely:

[0092]

[0093] If the seepage barrier is not broken through and only the original reserves are controlled, the water drive controlled reserves are the water drive controlled reserves.

[0094] Then the water drive controlled reserve V0=1 / (C O *K1).

[0095] If the seepage barrier is opened, some additional reserves will be created.

[0096] The total new waterflooding controlled reserves are calculated as follows:

[0097] V1=1 / (C0*K2);

[0098] Among them, the newly added reserves V2 = 1 / (C0*K2)-1 / (C O *K1).

[0099] Before carrying out high-pressure water injection to expand the reservoir, the method for calculating the required water injection volume includes the following steps:

[0100] First, before injecting water into the formation, it is necessary to calculate the required injection volume W iThe present invention provides two types of calculation methods, including theoretical calculation methods and on-site wellbore statistical methods. The theoretical calculation method includes the following steps:

[0101] First, based on the field data, the unit liquid production V0 at the wellhead when the formation pressure changes by one unit is obtained.

[0102] According to the calculation, the required formation pressure P is obtained. h .

[0103] According to the calculation method in Table 1 below, the required formation pressure P is calculated. h ; The formation pressure P is obtained by field testing or data through well testing x ;

[0104] Then the formation pressure difference P = P h -P x .

[0105] According to the formation pressure difference P and the unit liquid production V0, the required water injection volume W is i =P×V0.

[0106] Table 1

[0107]

[0108] In Table 1, the pressure unit is MPa; H is the depth in m.

[0109] Table 1 includes three types of calculation methods, which respectively obtain the minimum value of the required formation pressure through the fracture pressure, fracture closure pressure, and fracture extension pressure.

[0110] Based on the fracture pressure, calculate the required formation pressure P h , including PA Dickey method, Poisson's ratio method and pressure gradient method.

[0111] According to the PA Dickey method, P f =0.0023H×3 / 4;

[0112] Where P f Represents the formation fracture pressure, in MPa.

[0113] According to the Poisson's ratio method, P f =R / (1-R)×(P s -P t )+P r ,

[0114] Where P s is the overlying rock pressure, in MPa;

[0115] Pt is the formation pressure near the bottom of the injection well, in MPa;

[0116] R is Poisson's ratio, which is 0.3 in the present invention.

[0117] The principle of this method is that the rupture begins when the lateral force applied to the formation is equal to the horizontal principal stress of the formation, and the horizontal principal stress is caused by the pressure of the overlying rocks.

[0118] Therefore, this method is suitable for continuous sedimentary basins with new strata and less impact of tectonic movements, but not for areas with old strata and greater impact of tectonic movements.

[0119] According to the pressure gradient method, P f =0.018H

[0120] The principle of the pressure gradient method is to reflect the degree of change of the vertical pressure of the formation through the formation pressure gradient. The calculation method varies depending on the oil layer block and needs to be statistically analyzed based on a large amount of fracturing practice data.

[0121] Based on the fracture closure pressure, calculate the required formation pressure P h , based on experience, the formula is summarized to get P b =0.014H, where P b Fracture closure pressure. Fracture closure pressure refers to the pressure that causes fractures when the water pressure in the formation is too high, causing the stones or rocks exposed on the surface to be infiltrated by water molecules and then gradually lose water, resulting in a smaller volume. When water pressure is formed above the rock, it will cause the rock to deform and shrink to achieve equilibrium. This method is mostly applicable to areas with high water pressure in the formation.

[0122] According to the crack extension pressure, P y =0.016H, where P y The crack extension pressure.

[0123] When the formation pressure in the rock is greater than the fracture extension pressure, the existing hydraulic fractures can be opened and the fractures can be maintained, making them unable to close.

[0124] In summary, in order to achieve the purpose of expansion, the formation pressure must at least reach the closing pressure of the fracture, that is, to open the closed fracture, that is, the required formation pressure P h ≥0.014H.

[0125] On this basis, according to the actual formation conditions on site, if the fractures in the formation are to be kept open, the required formation pressure P h ≥0.016H.

[0126] According to the actual situation, if there are few fractures in the formation, it is necessary to consider using the calculation method of the fracture pressure in Table 1 to make the required formation pressure P h ≥P f.

[0127] During actual field operation, the liquid production at the wellhead when the formation pressure drops by 1 MPa is first calculated based on field data, and then converted to the underground volume V through various reservoir engineering methods. The formation pressure data is recorded using well test data and a pressure gauge.

[0128] Finally, the required water injection volume can be obtained by multiplying the calculated formation pressure difference with the unit liquid production obtained by the test.

[0129] The on-site wellbore statistics method is as follows:

[0130] On the basis of expanding the formation, it is necessary to combine field tests to calculate the required formation pressure P h The pressure after water injection is reached and the elastic expansion energy of crude oil is fully utilized, so that the injection volume of each round of high-pressure expansion water injection can be accurately designed.

[0131] The specific steps are:

[0132] First, test and calculate the formation pressure P before water injection in the field wellbore. i .

[0133] injecting water into the formation;

[0134] Statistical formation pressure P after water injection h ;

[0135] Finally, the formation pressure after water injection is divided by the original formation pressure to obtain the original pressure multiple.

[0136] Compare multiple original pressure multiples and select the original pressure multiple with the largest value as the empirical multiple.

[0137] On the basis of clarifying the required formation pressure, for a constant volume reservoir, the material balance equation without considering the compressibility of the injected water is shown in Equation 1, and the required injection volume for high-pressure water injection expansion can be obtained.

[0138] W i =NB oi C o (P h -P i )

[0139] Where W i is the required water injection volume, m 3 ;

[0140] N is the geological reserves of crude oil, 10 4 t;

[0141] B oi is the original crude oil volume coefficient, dimensionless;

[0142] Co is the crude oil compressibility factor, 1 / MPa;

[0143] P h is the required formation pressure, MPa;

[0144] P i is the formation pressure before water injection, MPa.

[0145] The required formation pressure P h Equal to the formation pressure P before water injection i The product of the experience multiplier.

[0146] Optionally, the empirical multiple of the present invention is 1.3.

[0147] Example 1

[0148] Combine the following Figure 1 The specific implementation of the method for calculating the water flooding controlled reserves of the oil reservoir high pressure expansion water injection according to the present invention is further described.

[0149] This embodiment is an implementation method of the on-site wellbore statistics method in the method for calculating the required water injection volume before water injection of the present invention.

[0150] First, the formation pressure P before water injection of seven wells was tested and counted. i ;

[0151] After water injection into the formation, the formation pressure P of the seven wells after water injection was calculated. h ;

[0152] Through statistics, the original pressure multiples of the seven wells are shown in Table 2.

[0153] In this embodiment, the wellbore with the largest original pressure multiple is taken as the basis, as shown in sequence number 7, and the wellbore has increased reserves by 367,200 tons and increased oil by 10,700 tons.

[0154] Required formation pressure after water injection P h is the formation pressure before water injection, P i 1.32 times, in this embodiment, 1.3 times is taken, that is, the empirical multiple is 1.3.

[0155] Table 2

[0156]

[0157] The wellbore statistics method of the present invention, when used, is calculated according to the formula W i =NB oi C o (P h -P i ), when calculating the injection volume of other wells in the site:

[0158] First, obtain the crude oil geological reserves N according to the data;

[0159] Then, according to the wellbore data or experiments, the original crude oil volume coefficient B is obtained. oi .

[0160] The crude oil volume coefficient is the ratio of the volume of crude oil underground to its volume after degassing on the ground. It can be calculated through experimental methods by measuring parameters such as crude oil density and viscosity at different temperatures and pressures.

[0161] Then calculate the crude oil compression coefficient C according to the data or o The crude oil compression coefficient refers to the volume change of a unit volume of formation crude oil when the crude oil pressure changes by 1 MPa. There are three commonly used methods for determining the crude oil compression coefficient: the pressure curve method, the compaction method, and the expansion volume ratio method. According to the pressure curve method, the coefficient is calculated by measuring the total volume change of crude oil under changing temperature, pressure, and specific pressure. The compaction method and the expansion volume ratio method determine the coefficient based on the natural expansion and compression of crude oil.

[0162] Formation pressure before water injection P i It refers to the original formation pressure, specifically the pressure in the middle of the oil layer measured in the exploration well before the oil field is put into production and development.

[0163] The methods used to obtain the original formation pressure include actual measurement method, well test method, pressure gradient method, limit method and equivalent depth method. In this embodiment, the well test method is used to determine the original formation pressure.

[0164] Finally, according to the empirical multiple, the formation pressure P after water injection is obtained. h 1.3 times the formation pressure before water injection P i , and then calculate the required water injection volume W i .

[0165] Example 2

[0166] Combine the following Figures 1 to 5 The specific implementation of the method for calculating the water flooding controlled reserves of the oil reservoir high pressure expansion water injection according to the present invention is further described.

[0167] This embodiment is a method for calculating the water flooding controlled reserves of the present invention.

[0168] In this embodiment, Well A stopped spraying due to insufficient energy, and the production effect was poor. Multiple rounds of conventional water injection to replace oil were carried out successively. After the well was opened, the water content was high, and the production was low and inefficient for a long time.

[0169] Well A is located in the fault-controlled karst area. Based on the analysis of seismic reflection characteristics, there are two sets of reservoirs around the well, and the distance between them and the well is relatively small.

[0170] Through the reserve carving method, it is determined that the static reserves of the well are 439,400 tons, and the energy indication curve during the self-flowing period shows obvious constant volume characteristics. The static reserves are 3.93 times the dynamic reserves. The well drilled a room group of 24 meters, with a small drilling depth and a large water avoidance height. It is not easy to communicate with the surrounding potential water bodies by overpressure expansion water injection. There is no water during the self-flowing period, the remaining oil is enriched, and it is located in the main stress direction of the branch fault. The water injection expansion resistance is relatively small, which is suitable for high-pressure water injection expansion.

[0171] like Figure 5 As shown in the figure, according to the formation conditions of Well A, two rounds of high-pressure expansion water injection were designed. The first round of water injection was 20413m 3 Restore formation pressure, second round of water injection 11086m 3 When the wellhead pressure reached 17.6Mpa, the water injection indication curve showed an inflection point, the second reservoir body was opened up, the new reserves were 155,100 tons, and water was continued to be injected to the formation pressure of 93.2Mpa, reaching 1.22 times the original formation pressure.

[0172] The slope of the first curve is K0 = 0.0033, the slope of the second curve is K1 = 0.0037, and the slope of the third curve is K2 = 0.0015; C0 = 17.15. According to the formula V = 1 / (C0*K), V0 = 17.6694*10 4 m 3 , V1=15.7592*10 4 m 3 V2=38.8727*10 4 m 3 .

[0173] From the crude oil density = 0.8115g / cm 3 The corresponding reserves of the three curves are: m0=14.34t, m1=12.79t, m2=31.55t.

[0174] After the well was opened, the average daily oil production increased by 17.4 tons, and the cumulative oil production increased by 5,495 tons, successfully converting a low-yield and inefficient well into a high-yield well.

[0175] The invention enriches the principle of carbonate rock water injection, explores and establishes a systematic high-pressure expansion water injection technology system. The successful application of this technology provides an effective way to manage failed and inefficient wells in the middle and late stages of carbonate rock water injection development in oil fields.

[0176] As shown in Table 3, the present invention has cumulatively implemented 38 rounds of high-pressure expansion water injection in 26 wells, with a cumulative water injection of 560,000 cubic meters, a cumulative increase in oil production of 34,000 tons, and an additional water drive controlled reserve of 2.6434 million tons; among them, 7 long-shutdown wells resumed production, and 5 inefficient wells became high-yield wells, with the highest daily oil increase level of 254 tons / day, the average daily oil increase level of 110 tons, and an annual restored production capacity of 33,000 tons.

[0177] Table 3

[0178]

[0179]

[0180] Based on the current water injection of 560,000 cubic meters, cumulative oil production of 34,000 tons, crude oil price of 5,000 yuan, water injection cost of 10.8 yuan / cubic meter, and operating cost of 710 yuan / ton, the additional output value of expansion and water injection is calculated as [cumulative oil × (crude oil price - unit crude oil operating cost) - pump truck water injection cost] × sharing coefficient × (1-30%) × (1+10%) = 107.6552 million yuan.

[0181] A device for calculating the controlled reserves of water flooding for high-pressure expansion water injection in an oil reservoir according to the present invention comprises:

[0182] Monitoring module, used to monitor and draw the relationship curve between injection volume and injection pressure during formation water injection;

[0183] The first processing module is used to calculate the slope of K1 and the crude oil compressibility coefficient C when only a single slope K1 curve appears on the water injection volume-water injection pressure curve. O Able to calculate water flooding controlled reserves V0;

[0184] The second processing module is used to generate a water injection volume-water injection pressure curve with slopes from K1 to K1. n When there are multiple curves, the slope of the curve K1 to the slope of the curve K n and crude oil compressibility C O , calculate the new water drive controlled reserves V1 and the newly added reserves V2.

[0185] A computer device of the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for calculating the water drive controlled reserves of the oil reservoir high pressure expansion water injection are implemented.

[0186] A computer-readable storage medium of the present invention stores a computer program, and when the computer program is executed by a processor, the steps of the method for calculating the water drive controlled reserves of the oil reservoir high-pressure expansion water injection are implemented.

[0187] Unless otherwise specified, the device elements involved in the above embodiments are all conventional device elements, and the structural settings, working modes or control modes involved are all conventional settings, working modes or control modes in the art unless otherwise specified.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs, characterized in that: The following steps are involved: S1: Monitor and draw the relationship curve between injection volume and injection pressure during formation water injection; S2: When only a single slope K1 curve appears on the relationship curve between water injection volume and water injection pressure, the water drive controlled reserves are calculated by K1 and the crude oil compressibility coefficient; S3: When the relationship curve between injection volume and injection pressure has slopes from K1 to K n When there are multiple curves, the slope of the curve K1 to the slope of the curve K n and crude oil compression coefficient, calculate the new water drive controlled reserves and additional reserves.

2. A method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs according to claim 1, characterized in that: In step S2, the calculation method of water flooding controlled reserves is as follows: V0=1 / (C O *K1); Where V0 is the waterflooding controlled reserves; C O is the crude oil compressibility factor; K1 is the slope of the curve.

3. The method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs according to claim 1, characterized in that: In step S3, the calculation formula of the new water flooding controlled reserves is V1 = 1 / (C0*K n ), the calculation formula for the newly added reserves is V2=1 / (C0*K n )-1 / (C O *K n-1 ); Where V1 is the new waterflooding controlled reserves; V2 is the newly added waterflooding controlled reserves; C O is the crude oil compressibility factor; K1, K n is the slope of the corresponding curve, where n>1.

4. The method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs according to claim 1, characterized in that: Before injecting water into the formation in step S1, the following steps are included: 1) Based on the field data, the liquid production at the wellhead when the unit formation pressure changes; 2) Obtain the required formation pressure through well testing; 3) Obtaining the formation pressure difference according to the required formation pressure and the original formation pressure; 4) Multiply the formation pressure difference by the unit liquid production to obtain the required water injection volume, and inject water into the formation according to the required water injection volume.

5. A method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs according to claim 4, characterized in that: In step 2), the required formation pressure is calculated as: h =0.018H, where P h is the formation pressure; H is the formation depth.

6. A method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs according to claim 4, characterized in that: In step 2), the required formation pressure is calculated as: h =0.014H, where P h is the formation pressure, and H is the formation depth.

7. The method for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs according to claim 1, characterized in that: Before injecting water into the formation in step S1, the following steps are included: Test and calculate the formation pressure P of the on-site wellbore before water injection i ; Calculate the formation pressure P after water injection h =1.3P i ; Calculate the required formation water injection volume W i =NB oi C o (P h -P i ), and according to the required water injection volume W i injecting water into the formation; Where W i Fill the required amount of water; B oi is the volume coefficient of the original crude oil; C o is the crude oil compressibility factor; P h is the required formation pressure; P i is the formation pressure before water injection.

8. A device for calculating the controlled reserves of water flooding for high pressure expansion water injection in oil reservoirs, characterized in that: include: Monitoring module, used to monitor and draw the relationship curve between injection volume and injection pressure during formation water injection; The first processing module is used to calculate the water drive controlled reserves by using K1 and the crude oil compressibility coefficient when only a curve with a single slope K1 appears on the water injection volume-water injection pressure curve; The second processing module is used to generate a water injection volume-water injection pressure curve with slopes from K1 to K1. n When there are multiple curves, the slope of the curve K1 to the slope of the curve K n and crude oil compression coefficient, calculate the new water drive controlled reserves and additional reserves.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for calculating the water flooding controlled reserves of the oil reservoir high-pressure expansion water injection as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating the water flooding controlled reserves of the oil reservoir high-pressure expansion water injection as claimed in any one of claims 1 to 7 are implemented.

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