A method for determining liquid production depletion time and combustion front position in a straight well plane fire flooding process

Abstract

The application provides a method for determining liquid production decline time and combustion front position in a straight well plane fire flooding process. The method for determining liquid production decline time comprises: fitting a first model and a second model based on liquid production data of a target production well in the last M months and the last N months from the ignition time of a gas injection well, respectively, wherein y is cumulative liquid production, and x is cumulative liquid production time; determining the liquid production decline time of the target production well based on the difference between p m , p n and the shape of the second model. The method for determining the combustion front position comprises: fitting a third model based on cumulative liquid production data of the target production well from the ignition time of the gas injection well; determining the cumulative liquid production corresponding to the target cumulative liquid production time of the target production well by using the third model; determining the average propagation speed of the fire line in the direction from the gas injection well to the target production well within the target cumulative liquid production time; and determining the combustion front position of the fire line in the direction from the gas injection well to the target production well at the target cumulative liquid production time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, in particular to a method for determining liquid production depletion time and combustion front position in the process of plane fire flooding in vertical well. BACKGROUND

[0002] Fire flooding is an important heavy oil recovery technology, which ignites the injected air into the oil layer to make it a mobile heat source, thereby significantly improving the mobility of heavy oil and making heavy oil flow to the bottom of the production well, and ultimately achieving the purpose of heavy oil recovery. The position prediction of the fire burning front (i.e. the combustion front) in the process of plane fire flooding in vertical well is one of the key indicators to judge whether the fire flooding technology is successful or not. By monitoring the state of the fire line advance, the advance distance of the fire line in different directions can be controlled in real time. For unevenly affected well groups, production control measures can be taken in time to guide the more uniform and stable expansion of the fire cavity, thereby improving the overall development of the reservoir, which is of great significance to fire flooding development.

[0003] Currently, the commonly used fire line monitoring methods are: tracer monitoring method, theoretical calculation method and dynamic analysis method. These methods monitor the changes of the bottom hole temperature and fluid composition of the production well, and combine numerical simulation methods to perform history matching on the actual production data, thereby predicting the position of the combustion front. However, due to the actual fire flooding production state is usually affected by multiple factors such as gas drive, water drive, and the lack of close combination of actual production and combustion front position monitoring methods, it is difficult to accurately predict the position of the combustion front in the process of field production by using tracer monitoring, theoretical calculation, numerical simulation and other methods. SUMMARY

[0004] The purpose of the present application is to provide a method for determining the liquid production depletion time in the process of plane fire flooding in vertical well.

[0005] Another purpose of the present application is to provide a method for dynamically predicting the position of the combustion front in the process of plane fire flooding in vertical well.

[0006] In order to achieve the above purpose, the present application provides the following two technical solutions.

[0007] In the first aspect, the present application provides a method for determining the liquid production depletion time in the process of plane fire flooding in vertical well, wherein the method comprises:

[0008] Obtaining the cumulative liquid production data of the target production well from the ignition time of the gas injection well in the process of plane fire flooding in vertical well;

[0009] Based on the liquid production data of the target production well for M months before the ignition time of the gas injection well, a first model is fitted; wherein the first model is a calculation model of cumulative liquid production with respect to liquid production time, and the first model is:

[0010]

[0011] wherein y is cumulative liquid production; x is cumulative liquid production time (counted from the ignition time of the gas injection well); A 1m , A 2m , x0, p m are all coefficients;

[0012] based on the cumulative liquid production data of the target production well from the ignition time of the gas injection well for N months, a second model is fitted; wherein N is greater than M; wherein the second model is a calculation model of cumulative liquid production with respect to liquid production time, and the second model is:

[0013]

[0014] wherein y is cumulative liquid production; x is cumulative liquid production time (counted from the ignition time of the gas injection well); A 1n , A 2n , x0, p n are all coefficients;

[0015] based on the difference between p m , p n in the first model and the second model, and in combination with the form of the second model, the liquid production depletion time of the target production well is determined.

[0016] In a second aspect, the present application provides a method for determining the position of the combustion front in the process of vertical well plane fire flooding, wherein the method comprises:

[0017] obtaining the cumulative liquid production data of the target production well from the ignition time of the gas injection well in the process of vertical well plane fire flooding;

[0018] based on the cumulative liquid production data of the target production well from the ignition time of the gas injection well, a third model is fitted; wherein the third model is a calculation model of cumulative liquid production with respect to liquid production time, and the third model is:

[0019]

[0020] wherein y is cumulative liquid production; x is cumulative liquid production time (counted from the ignition time of the gas injection well); A1, A2, x0, p are all coefficients;

[0021] using the third model, the cumulative liquid production corresponding to the target cumulative liquid production time of the target production well is determined;

[0022] based on the cumulative liquid production corresponding to the target cumulative liquid production time of the target production well, the average propagation speed of the fire line in the target cumulative liquid production time from the gas injection well to the target production well is determined;

[0023] Determine the combustion front position of the fire line from the injection well to the target production well in the target cumulative liquid production time based on the average advancing speed of the fire line from the injection well to the target production well in the target cumulative liquid production time.

[0024] The technical solution provided by the present application can determine the liquid production depletion time, which can guide the fire flooding control in the straight well plane fire flooding process, and determine the combustion front position, which can realize the dynamic prediction of the combustion front position. The technical solution provided by the present application is simple to operate, high in accuracy, and strong in economic applicability. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A flow chart of the method for determining the liquid production depletion time in the straight well plane fire flooding process in an embodiment.

[0026] Figure 2 A flow chart of the method for determining the combustion front position in the straight well plane fire flooding process in an embodiment.

[0027] Figure 3 A schematic diagram of a one-dimensional combustion tube structure in an embodiment.

[0028] Figure 4 A schematic diagram of a three-dimensional fire flooding physical experiment device structure in an embodiment.

[0029] Figure 5 A schematic diagram of the fire cavity expansion under the condition of formation heterogeneity in an embodiment.

[0030] Figure 6 A simplified schematic diagram of the fire cavity under the condition of formation heterogeneity in an embodiment.

[0031] Figure 7 A simplified top view of the fire cavity under the condition of formation heterogeneity in an embodiment.

[0032] Figure 8 A cumulative liquid production fitting curve graph when the oil saturation is 0.66 in the three-dimensional fire flooding physical experiment.

[0033] Figure 9 A cumulative liquid production fitting curve graph when the oil saturation is 0.93 in the three-dimensional fire flooding physical experiment.

[0034] Figure 10A A first model fitting curve graph of Well A.

[0035] Figure 10B A second model fitting curve graph of Well A.

[0036] Figure 11 A second-order derivative curve graph of the second model of Well A.

[0037] Figure 12A Fitted curve plot for the first model for Well B.

[0038] Figure 12B Fitted curve plot for the second model for Well B.

[0039] Figure 13A Fitted curve plot for the first model for Well C.

[0040] Figure 13B Fitted curve plot for the second model for Well C.

[0041] Figure 14 Illustration of the 8 well pad.

[0042] Figure 15A Cumulative liquid production data plot for Well 84.

[0043] Figure 15B Cumulative liquid production data plot for Well 83.

[0044] Figure 15C Cumulative liquid production data plot for Well 82.

[0045] Figure 15D Cumulative liquid production data plot for Well 81.

[0046] Figure 16A Fitted curve plot for the third model for Well 84.

[0047] Figure 16B Fitted curve plot for the third model for Well 83.

[0048] Figure 16C Fitted curve plot for the third model for Well 82.

[0049] Figure 16D Fitted curve plot for the third model for Well 81.

[0050] Figure 17A Illustration of the well pattern in Example 5.

[0051] Figure 17B Illustration of the fire chamber thickness after overlap in Example 5. DETAILED DESCRIPTION

[0052] In order to make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to briefly describe the technical solutions in the embodiments of the present application in a complete and clear manner. Obviously, the described embodiments are only a part of embodiments of the present application, rather than all the embodiments of the present application. Based upon the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0053] Taking the ignition moment as zero point, fitting the cumulative liquid production data The cumulative liquid production fitting curve is obtained, wherein y is the cumulative liquid production amount, x is the cumulative liquid production time (counted from the ignition moment of the gas injection well), A1, A2, x0 and p are all coefficients. The overall change rule of the cumulative liquid production fitting curve is: gentle rise-rapid rise-gentle rise, which corresponds to the actual production process in the field. The curve can be further divided into three stages: gas drive stage-fire drive stage-liquid production depletion stage. The second stage of the curve corresponds to the oil wall accumulation and the rapid advance of the fire line stage. Combined with the indoor physical model experiment, the liquid production data in the stage is selected to calculate the advance speed of the fire line, so that the actual expansion form of the fire cavity in the fire flooding process can be better inverted. At the same time, the time node of the appearance of the third stage of the curve can help to determine the liquid production depletion time, which is helpful to take the fire flooding control measures in advance to prevent the production well from entering the liquid production depletion. On this basis, the present application provides the following technical scheme:

[0054] Referring to Figure 1 , a method for determining the liquid production depletion time in the straight well plane fire flooding process is provided in a specific embodiment of the present application, wherein the method comprises:

[0055] Step S1: obtaining the cumulative liquid production data of the target production well from the ignition moment of the gas injection well in the straight well plane fire flooding process;

[0056] Step S2: based on the liquid production data of the target production well from the ignition moment of the gas injection well for M months, a first model is fitted; wherein the first model is a calculation model of the cumulative liquid production amount about the liquid production time, and the first model is:

[0057]

[0058] In the formula, y is the cumulative liquid production amount, x is the cumulative liquid production time (counted from the ignition moment of the gas injection well), A 1m , A 2m , x0 and p m are all coefficients;

[0059] Step S3: based on the liquid production data of the target production well from the ignition moment of the gas injection well for N months, a second model is fitted; wherein N is greater than M; wherein the second model is a calculation model of the cumulative liquid production amount about the liquid production time, and the second model is:

[0060]

[0061] In the formula, y is the cumulative liquid production amount, x is the cumulative liquid production time (counted from the ignition moment of the gas injection well), A 1n , A 2n , x0 and p n are all coefficients;

[0062] Step S4: Based on p in the first model and the second model m p n The difference, combined with the morphology of the second model, determines the production depletion time of the target well.

[0063] In one instance, analysis of the production data of each well in a vertical well planar fire-flooding pilot test area revealed that, according to the formula... A cumulative production curve is obtained by fitting the curve, where y is the cumulative production volume; x is the cumulative production time (starting from the ignition time of the injection well); A1, A2, x0, and p are coefficients. When the derivative of a point on the cumulative production curve has no change, the rate of change is -2 × 10⁻⁶. -5 to -6×10 -5 When the production well reaches a certain range, it will enter the production depletion stage. Therefore, under the condition of sufficient production data, after fitting the production data to obtain the cumulative production curve, we find that the derivative has no change rate at -2×10. -5 to -6×10 -5 The corresponding timeframe allows us to determine the range of future production decline times, enabling early control of production wells. However, in actual production, it's necessary to predict the future production decline time using earlier cumulative production data (e.g., 0-10 months, 0-15 months). Simply fitting and extending these early data doesn't accurately simulate the true changes in future cumulative production. In this case, we determine -2×10 -5 to -6×10 -5 In practice, the inflection point found is often not the point where the cumulative production volume eventually stabilizes, but rather a small stage in the production process where production volume declines. To address this problem, the inventors discovered that the exponent p in the cumulative production fitting curve is a key factor affecting the curve's shape. Based on the cumulative production fitting curves of two adjacent time periods in the initial production phase (e.g., 0-10 months, 0-15 months), the absolute value of the difference in the exponent p is calculated. Combined with the instantaneous rate of change of the curve, the curve shape can be classified, thus achieving a more accurate prediction of the production exhaustion time. The results show that all produced wells can be divided into two categories: one category has relatively similar predicted inflection point values ​​across different production time lengths, which can be unified into a small range; the other category has significantly different inflection point values ​​across different production time ranges, but the longer the production time (i.e., the more known data points), the closer the inflection point position is to a definite value. The specific relationships are shown in Table 1, derived from calculations using a large amount of field produced well cumulative production data.

[0064] Table 1. Judgment Table for Adjustment Timing

[0065]

[0066] Based on the above relationships, it is possible to predict the future production trends of different production wells using relatively little production data, thereby determining the approximate time period when production will show significant decline. Combined with specific production conditions, the timing for adjustment of different production wells can be obtained. Based on this, the following further optimization scheme is proposed:

[0067] Furthermore, based on p in the first model and the second model m p n The difference, combined with the morphology of the second model, determines the production depletion time of the target well, including:

[0068] When p m p n When the absolute value of the difference is greater than 2, the production depletion time of the target well is 50-55 months.

[0069] When p m p n When the absolute value of the difference is less than or equal to 2, if the curve shape of the second model is S-shaped, then the production exhaustion time of the target production well is the production time corresponding to the second inflection point of the curve of the second model.

[0070] When p m p n When the absolute value of the difference is less than or equal to 2, and the curve shape of the second model is not S-shaped (at this time the curve shape is a kind of straight line), then the production depletion time of the target well is 40-45 months.

[0071] Furthermore, the production time corresponding to the second inflection point of the curve in the second model is determined in the following way:

[0072] Obtain the second derivative of the second model (i.e., the rate of change of the derivative of the first model), and determine the value of the second derivative of the second model as -2 × 10⁻⁶. -5 to -6×10 -5 The production time corresponding to the second inflection point of the curve in the second model is the production time corresponding to the second inflection point.

[0073] Furthermore, the determined fluid depletion time can be used to determine the timing of fire drive control, thereby guiding the fire drive control during the vertical well planar fire drive process; for example, the determined fluid depletion time can be used as the timing of fire drive control.

[0074] Furthermore, the difference between N and M is 5-8; even further, the difference between N and M is 5.

[0075] Furthermore, the value of M is not less than 10, and the value of N is not less than 15;

[0076] For example, the value of M is 10, and the value of N is 15;

[0077] For example, the value of M is 20, and the value of N is 25.

[0078] After multiple rounds of steam development, heavy oil reservoirs develop underground secondary water bodies, which often results in the production wells producing a large amount of water in the early stages of gas injection. In the early stages of fire drive, the fire chamber is near the wellbore of the gas injection well, and the dynamic response of the production well should only be the effect of gas drive, not a direct result of fire drive. In addition, through a large number of one-dimensional combustion tube and three-dimensional fire drive physical experiments, it was found that only flue gas and trace amounts of liquid water are produced in the fire chamber in the early stages of expansion. The large amount of water generated during the early steam development stage is usually stored in some spaces with good reservoir permeability (or gas channeling channels). When gas is injected into the injection well, air or flue gas rapidly displaces the liquid water from these channels. Therefore, if the production dynamics are analyzed directly based on the cumulative production volume, the large amount of produced water will inevitably have a significant impact on the analysis results. At the same time, in the initial stage of ignition, the fire chamber has not yet expanded. At this time, under the action of pressure difference, the dynamic response of the production well is mainly due to gas drive, not fire drive. Therefore, in order to eliminate the above interference and make the results more accurate, it is necessary to select the cumulative oil production and perform correction, that is, multiply the original production data by a correction factor so that the corrected data has a good similarity to the production dynamics at the outlet end during normal combustion in the physical model experiment. Based on this, the following further optimization scheme is proposed:

[0079] Furthermore, the cumulative production data of the target production well from the ignition time of the gas injection well during the vertical well planar fire drive process includes:

[0080] Acquire the cumulative production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process;

[0081] The cumulative production data of the target production well from the ignition time of the injection well is corrected to obtain the cumulative production data of the target production well from the ignition time of the injection well.

[0082] Furthermore, the correction of the cumulative production data of the target production well from the ignition time of the injection well is performed using the following formula:

[0083] Q 真实 =α·Q 现场

[0084] In the formula, Q 真实 Q represents the corrected cumulative product volume. 现场 The cumulative liquid production on site; α is a correction coefficient, preferably α is 1.1-1.2.

[0085] See Figure 2 A specific embodiment of the present invention provides a method for determining the position of the combustion front during a vertical well planar fire drive process, wherein the method includes:

[0086] Step A1: Obtain the cumulative fluid production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process;

[0087] Step A2: Based on the cumulative production data from the ignition time of the target production well and the self-injection well, a third model is fitted to obtain the third model; wherein, the third model is a calculation model of the cumulative production volume with respect to the production time, and the third model is:

[0088]

[0089] In the formula, y is the cumulative fluid production; x is the cumulative fluid production time (starting from the ignition time of the injection well); A1, A2, x0, and p are all coefficients.

[0090] Step A3: Using the third model, determine the cumulative production volume corresponding to the target cumulative production time of the target production well;

[0091] Step A4: Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, determine the average advance speed of the fire line in the direction from the gas injection well to the target production well within the target cumulative production time;

[0092] Step A5: Based on the average advance speed of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time, determine the position of the combustion leading edge of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time.

[0093] Furthermore, the cumulative production data of the target production well from the ignition time of the gas injection well during the vertical well planar fire drive process includes:

[0094] Acquire the cumulative production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process;

[0095] The cumulative production data of the target production well from the ignition time of the injection well is corrected to obtain the cumulative production data of the target production well from the ignition time of the injection well.

[0096] Furthermore, the correction of the cumulative production data of the target production well from the ignition time of the injection well is performed using the following formula:

[0097] Q 真实 =α·Q 现场

[0098] In the formula, Q 真实 Q represents the corrected cumulative product volume. 现场 The cumulative liquid production on site; α is a correction coefficient, preferably α is 1.1-1.2.

[0099] Furthermore, when the injection-production well network where the target production well is located is a single injection-multiple production network, the average advance speed of the fire line in the direction from the gas injection well to the target production well within the target cumulative production time is determined based on the cumulative production volume corresponding to the target cumulative production time of the target production well. This includes:

[0100] Obtain the average width and average thickness of the fire chamber corresponding to the target cumulative liquid production time;

[0101] Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, the average width of the fire chamber expansion, and the average thickness of the fire chamber, the average advance speed of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined.

[0102] Furthermore, the average advance rate of the fire line in the direction from the injection well to the target production well during the target cumulative production time is determined by the following formula:

[0103]

[0104] In the formula, V L ΔQ is the average advance speed at the fire line, in m / d; ΔQ is the cumulative liquid production, in m³ / d. 3 b is the average width of the fire chamber expansion, in meters; h is the average thickness of the fire chamber, in meters; Δt is the target cumulative liquid production time, in days.

[0105] In one example, using Determine the average advance rate of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time, where V L ΔQ is the average advance speed at the fire line, in m / d; ΔQ is the cumulative liquid production, in m³ / d. 3 b is the average width of the fire chamber expansion, in meters; h is the average thickness of the fire chamber, in meters; Δt is the target cumulative liquid production time, in days; the results are shown in Table 2.

[0106] Table 2

[0107]

[0108]

[0109] The average thickness of the fire chamber can be determined through field observation or empirical values, but is not limited to these methods. Furthermore, the average thickness of the fire chamber is determined based on the thickness of the perforated section of the injection well and the distance between the injection well and the target production well.

[0110] Furthermore, if the fire line does not extend beyond the top of the reservoir during the process of advancing from the gas injection well to the target production well, the average thickness of the fire chamber is determined based on half the thickness of the perforated section of the gas injection well. Typically, the average thickness of the fire chamber is 0.7-0.8 times half the thickness of the perforated section of the gas injection well.

[0111] Furthermore, when the fire line advances from the gas injection well to the target production well and overlaps the top of the reservoir, the average thickness of the fire chamber is determined by multiplying the ratio of the distance from the gas injection well to the target production well and the distance from the gas injection well to the position where the fire line overlaps the top of the reservoir by half the thickness of the perforated section of the gas injection well. Typically, the average thickness of the fire chamber is 0.5-0.8 times the product.

[0112] The average expansion width of the fire chamber can be determined through field observation or empirical values, but is not limited to these methods. Further, the average expansion width of the fire chamber is the expansion width of the fire chamber corresponding to the point where the fire line advances to the middle of the target production well and injection well. Further, the average expansion width of the fire chamber is determined based on the fire-driven injection-production well network where the target production well is located.

[0113] Furthermore, the average expansion width of the fire chamber is determined based on half the distance between the target production well and its adjacent wells. Typically, the average expansion width of the fire chamber is 0.8-0.9 times half the distance between the target production well and its adjacent wells.

[0114] In one example, a three-dimensional fire-drive physics experimental device (such as...) was used. Figure 4 The experiment simulated the flow state of fluid during fire-driven combustion (as shown). The experimental setup included a reactor body, an end cap at the open end of the reactor body, a simulated gas injection well inside the reactor body, a temperature measuring point, and a simulated oil production well. The injection-production well distance was controlled at 11 cm. Temperature changes and fluid production were monitored at oil saturation levels of 0.66 and 0.93, respectively. The fire chamber expansion state was determined by reconstructing the coking zone shape, and the average advance velocity of the fire line was determined using the following formula:

[0115]

[0116] In the formula, V L ΔQ is the average advance speed at the fire line, in m / d; ΔQ is the cumulative liquid production, in m³ / d. 3 b is the average width of the fire chamber, in meters; h is the average thickness of the fire chamber, in meters; Δt is the fire line advance time, in days.

[0117] During vertical well planar fire drive, the fire chamber expands in an ellipsoidal shape (e.g.) Figure 5 As shown), to simplify the calculation process, a top-down view is adopted, and the expanded shape of the fire cavity is simplified to a rhombus (as shown). Figure 6 , Figure 7As shown), the long diagonal of the rhombus represents the fire line advance distance, and the sides of the long and short angles of the rhombus represent the average width of the fire chamber expansion.

[0118] The cumulative liquid yield fitting curve when the oil saturation is 0.66 is as follows: Figure 8 As shown, the cumulative liquid production fitting curve when the oil saturation is 0.93 is as follows: Figure 9 As shown;

[0119] The results of three-dimensional fire drive physics experiments show that when the injected gas flows heterogeneously in all directions, the fire line advance speed is 4-6 cm / d.

[0120] Furthermore, when the injection-production well network where the target production well is located is a single injection-single production network, the average advance speed of the gas injection well to the target production well within the target cumulative production time is determined based on the cumulative production volume corresponding to the target cumulative production time of the target production well. This includes:

[0121] Obtain a first velocity ratio; wherein the first velocity ratio is the ratio of the average advance velocity of the fire line to the average movement velocity of the formation fluid;

[0122] Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, determine the average formation fluid migration velocity corresponding to the target cumulative production time of the target production well.

[0123] Based on the average formation fluid movement velocity corresponding to the target cumulative production time of the target production well, and combined with the first velocity ratio, the average advance velocity of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined.

[0124] Furthermore, the average advance rate of the fire line in the direction from the injection well to the target production well during the target cumulative production time is determined by the following formula:

[0125] V L =β·V F

[0126] In the formula, V L V is the average advancing speed on the front line; β is the first speed ratio, with dimensionless units; F This represents the average velocity of the liquid.

[0127] Furthermore, based on the cumulative production volume corresponding to the target cumulative production time of the target production well, the average formation fluid migration velocity corresponding to the target cumulative production time of the target production well can be determined using conventional methods in this field.

[0128] Furthermore, obtaining the first speed ratio includes:

[0129] To obtain formation permeability and oil saturation;

[0130] Determine the first velocity ratio corresponding to formation permeability and oil saturation;

[0131] Furthermore, determining the first velocity ratio corresponding to formation permeability and oil saturation includes:

[0132] Through indoor one-dimensional combustion tube fire drive experiments under formation permeability and oil saturation conditions, the first velocity ratio corresponding to formation permeability and oil saturation was determined.

[0133] Furthermore, one-dimensional combustion tube fire-drive experiments were conducted under different permeabilities and oil saturation conditions to determine the average advance velocity of the fire line and the average movement velocity of the formation fluid corresponding to different permeabilities and oil saturation. Based on these average advance velocities and average movement velocities, a first velocity ratio corresponding to different permeabilities and oil saturation was determined. A first velocity ratio determination chart was then prepared based on this first velocity ratio. Finally, based on the formation permeability and oil saturation, the first velocity ratio was determined using the first velocity ratio determination chart to determine the first velocity ratio corresponding to the formation permeability and oil saturation.

[0134] In one example, a one-dimensional combustion tube experimental setup was used to simulate the flow state of fluid during fire-driven experiments; the one-dimensional combustion tube used in the experiment (such as...) Figure 3 (As shown), the tube is 60cm long and 38mm in inner diameter. Five temperature measurement points (T2, T3, T4, T5, and T6) are distributed on the tube wall to monitor temperature changes at different locations within the combustion tube during combustion. The injection-production pressure difference is controlled at 1MPa, and the injection rate is 3L / min. Temperature change data and cumulative production data are obtained under different permeability and oil saturation conditions. First, the combustion state is determined based on the temperature monitoring results during the experiment. Then, the cumulative production data is analyzed.

[0135] ① Determine the average advance velocity V of the fire front in the one-dimensional combustion tube by measuring the time when the temperature peak appears during the advance of the fire front leading edge. L :

[0136]

[0137] In the formula, V L Δt represents the average advance speed of the fire line, in cm / min; L represents the distance from T2 to T5 in the one-dimensional combustion tube, in cm; Δt represents the time it takes for the fire line to advance from T2 to T5, in min.

[0138] ②Based on cumulative product data (selected) Production data from the fire-driven phase in the cumulative liquid production fitting curve were used to determine the average liquid migration velocity V.F :

[0139]

[0140] In the formula, V F ΔQ is the average liquid velocity, in cm / min; ΔQ is the cumulative liquid production from T2 to T5, in g; Δt is the time from T2 to T5, in min; A is the cross-sectional area of ​​the one-dimensional combustion tube, in cm². 2 ; Porosity, for example, 0.35.

[0141] ③ Determine the average advance speed of the fire line (V) L ) and the average moving velocity of the liquid (V) F The ratio of the first velocity to the first velocity is:

[0142]

[0143] In the formula, V F V represents the average velocity of the liquid, expressed in cm / min. L β is the average advance speed on the front line, in cm / min; β is the first velocity ratio, in dimensionless units.

[0144] Experimental results show that the value of the first velocity ratio β ranges from 1.5 to 3, as detailed in Table 3.

[0145] Table 3

[0146]

[0147] Furthermore, the first speed ratio is 1.5-3.

[0148] Example 1

[0149] This embodiment provides a method for determining the fluid production depletion time during vertical well planar fire flooding, specifically including the following steps:

[0150] 1) Obtain the cumulative production data of the target production well from the ignition time of the gas injection well during the vertical well planar fire drive process; correct the cumulative production data of the target production well from the ignition time of the gas injection well to obtain the cumulative production data of the target production well from the ignition time of the gas injection well; wherein, the correction of the cumulative production data of the target production well from the ignition time of the gas injection well is performed by the following formula:

[0151] Q 真实 =α·Q 现场

[0152] In the formula, Q真实 Q represents the corrected cumulative product volume. 现场 The cumulative liquid production on-site; α is a correction factor with a value of 1.1;

[0153] 2) Based on the production data of the target production well for the 10 months prior to the ignition time of the injection well, a first model was fitted; wherein, the first model is a calculation model for the cumulative production volume with respect to the production time, and the first model is:

[0154]

[0155] In the formula, y represents the cumulative fluid production; x represents the cumulative fluid production time (starting from the ignition time of the injection well); A 1m A 2m x0, p m All are coefficients;

[0156] 3) Based on the production data of the target production well for the 15 months prior to the ignition time of the injection well, a second model is fitted; wherein, the second model is a calculation model for the cumulative production volume with respect to the production time, and the second model is:

[0157]

[0158] In the formula, y represents the cumulative fluid production; x represents the cumulative fluid production time (starting from the ignition time of the injection well); A 1n A 2n x0, p n All are coefficients;

[0159] 3) Based on p in the first model and the second model m p n The difference, combined with the morphology of the second model, determines the production depletion time of the target well. Specifically:

[0160] When p m p n When the absolute value of the difference is greater than 2, the production depletion time of the target well is 50-55 months.

[0161] When p m p n When the absolute value of the difference is less than or equal to 2, if the curve shape of the second model is S-shaped, then the production exhaustion time of the target production well is the production time corresponding to the second inflection point of the curve of the second model; wherein, the production time corresponding to the second inflection point of the curve of the second model is determined in the following way:

[0162] Obtain the second derivative of the second model (i.e., the rate of change of the derivative of the first model), and determine the value of the second derivative of the second model as -2 × 10⁻⁶. -5 to -6×10 -5The production time corresponding to the second inflection point of the curve in the second model is the production time corresponding to the second inflection point.

[0163] When p m p n If the absolute value of the difference is less than or equal to 2, and the curve shape of the second model is not S-shaped (at this time the curve shape is a kind of straight line), then the production depletion time of the target well is 40-45 months.

[0164] In this embodiment, the first model is like Figure 10A As shown; the second model is like Figure 10B As shown; the absolute value of the difference between pm and pn is < 2 and the curve shape of the second model is S-shaped, the second derivative value of the second model is -2 × 10. -5 to -6×10 -5 The corresponding production time is 52-56 months (the second derivative of the second model is as follows). Figure 11 As shown in the figure, it can be determined that well A should have started to experience production fluid depletion as early as 52-56 months of fire-driven production.

[0165] Example 2

[0166] This embodiment provides a method for determining the fluid production depletion time during a vertical well planar fire attack process, specifically for determining the fluid production depletion time of well B during a vertical well planar fire attack process. The specific steps are the same as in Embodiment 1.

[0167] In this embodiment, the first model is like Figure 12A As shown; the second model is like Figure 12B As shown, the absolute value of the difference between pm and pn is >2, which indicates that well B should have started to experience production fluid depletion as early as 50-55 months of fire-driven production.

[0168] Example 3

[0169] This embodiment provides a method for determining the fluid production depletion time during vertical well planar fire attack, specifically for determining the fluid production depletion time of well C during vertical well planar fire attack. The specific steps are the same as in Embodiment 1.

[0170] In this embodiment, the first model is like Figure 13A As shown; the second model is like Figure 13B As shown; the absolute value of the difference between pm and pn is <2 and the curve shape of the second model is not S-shaped (at this time the curve shape is a kind of straight line). Therefore, it is judged that well C should start to experience production fluid depletion as early as 40-45 months of fire-driven production.

[0171] Example 4

[0172] This embodiment provides a method for determining the production exhaustion time during a vertical well planar fire drive process, which is used to determine the production exhaustion time of each well in each well group in a vertical well planar fire drive well area. The specific steps are the same as in Embodiment 1, and the results are shown in Table 4.

[0173] To verify the effectiveness of the method for determining the production exhaustion time provided by this invention, the actual production exhaustion times of these wells were statistically analyzed, and the results are shown in Table 4.

[0174] Table 4

[0175]

[0176]

[0177]

[0178] As shown in the table, only 4 out of 45 wells in the 14 well groups had significant deviations in production depletion time, achieving an accuracy of 91.11%. For wells with significant deviations between predicted and actual times, the absolute values ​​of the differences between PM and Pn often tend to be very close to 2, leading to unclear judgment boundaries and biased results. For such wells, more production data (e.g., calculating the absolute values ​​of the differences between PM and Pn using cumulative production curves from 0-25 months and 0-20 months) are needed to assist in the judgment.

[0179] Example 5

[0180] This embodiment provides a method for determining the position of the combustion front during a vertical well planar fire drive process, used to determine the position of the combustion front in the 8-well group (e.g., in Embodiment 4). Figure 14 The combustion leading edge position (as shown) is determined by the following steps:

[0181] 1) Obtain the cumulative production data of the target production well from the ignition time of the injection well during the vertical well planar fire drive process (e.g., Figure 15A , Figure 15B , Figure 15C , Figure 15D (As shown); The cumulative production data of the target production well from the ignition time of the injection well is corrected to obtain the cumulative production data of the target production well from the ignition time of the injection well; wherein, the correction of the cumulative production data of the target production well from the ignition time of the injection well is performed by the following formula:

[0182] Q 真实 =α·Q 现场

[0183] In the formula, Q 真实 Q represents the corrected cumulative product volume.现场 The cumulative liquid production on-site; α is a correction factor with a value of 1.1;

[0184] 2) Based on the cumulative production data from the ignition time of the target production well and the self-injection well, a third model is fitted; wherein, the third model is a calculation model for the cumulative production volume with respect to the production time, and the third model is:

[0185]

[0186] In the formula, y represents the cumulative fluid production; x represents the cumulative fluid production time (starting from the ignition time of the injection well); A1, A2, x0, and p are all coefficients; the results are shown in Table 5. Figure 16A , Figure 16B , Figure 16C , Figure 16D As shown;

[0187] Table 5

[0188] Hash 84 83 82 81 [A1] -0.00056 -0.00081 -0.03551 -0.00208 [A2] 0.06489 0.04242 1.08596 0.1229 X0 25.9397 16.8413 24.09955 18.0482 p 3.7637 5.5262 1.23058 1.5234 [R 2 ]]> 0.990 0.990 0.995 0.995

[0189] 3) Using the third model, determine the cumulative production volume corresponding to the target cumulative production time of the target production well, as shown in Table 6;

[0190] 4) Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, determine the average advance speed of the fire line in the direction from the injection well to the target production well within the target cumulative production time, specifically including:

[0191] The average width and average thickness of the fire chamber are obtained; the average thickness of the fire chamber is determined based on the perforation parameters of the injection well; based on the cumulative production volume corresponding to the target cumulative production time of the target production well, the average width and average thickness of the fire chamber, the average advance velocity of the fire line in the direction from the injection well to the target production well during the target cumulative production time is determined by the following formula (the results are shown in Table 6):

[0192]

[0193] In the formula, V L ΔQ is the average advance speed at the fire line, in m / d; ΔQ is the cumulative liquid production, in m³ / d. 3 b is the average width of the fire chamber expansion, in meters; h is the average thickness of the fire chamber, in meters; Δt is the target cumulative liquid production time, in days.

[0194] Well Group 8 Figure 17AThe diagram shows a reverse seven-point well pattern, with one injection well corresponding to six production wells, an average well spacing of 50m, and an average perforation section length of 6m. When the field fire-drive fire line advances to the middle of the injection and production wells, the rate of change in the fire chamber thickness decreases significantly, and the average expansion width of the fire chamber is approximately 20-25m. Based on this, the average expansion width of the fire chamber is taken as 20m. Regarding the average thickness of the fire chamber, due to the over-covering phenomenon, the fire line almost completely over-covers the top of the production well when it advances to 5m from the production well, forming a triangular shape with the injection well and the bottom of the perforation section (e.g., ...). Figure 17B As shown in the figure, the average thickness of the fire chamber is about 1.5-2.5m. Based on this, the average thickness of the fire chamber is taken as 2m.

[0195] Based on the average advance velocity of the fire line in the direction from the gas injection well to the target production well within the target cumulative production time, the combustion leading edge position of the fire line in the direction from the gas injection well to the target production well within the target cumulative production time is determined; wherein, the average advance velocity of the fire line within the target cumulative production time multiplied by the cumulative production time is the combustion leading edge position of the fire line in the direction from the gas injection well to the target production well within the target cumulative production time; the results are shown in Table 6.

[0196] Table 6

[0197]

[0198]

[0199] Further calculations of the fire chamber expansion area at different times (as shown in Table 7) show that the four production wells in this well group are relatively uniformly affected, and the fire line advances a long distance along the direction of production well 82.

[0200] Table 7

[0201] Production time month Firebox expansion area m 3 ]]> 20 615 30 1305 34 1607.48

[0202] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the fluid depletion time during planar fire-flooding in vertical wells, wherein, The method includes: Acquire the cumulative fluid production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process; Based on the production data of the target production well over the M months prior to the ignition time of the injection well, a first model was fitted; wherein, the first model is a calculation model for the cumulative production volume with respect to production time, and the first model is: In the formula, y is the cumulative liquid production volume; x is the cumulative liquid production time; A 1m A 2m x0, p m All are coefficients; Based on the production data of the target production well over the N months prior to the ignition time of the injection well, a second model was fitted; where N is greater than M; the second model is a calculation model for the cumulative production volume with respect to production time, and the second model is as follows: In the formula, y is the cumulative liquid production volume; x is the cumulative liquid production time; A 1n A 2n x0, p n All are coefficients; Based on the first model and the second model, p m p n The difference, combined with the morphology of the second model, determines the production depletion time of the target well. Among them, p is based on the first model and the second model. m p n The difference, combined with the morphology of the second model, determines the production depletion time of the target well, including: When p m p n When the absolute value of the difference is greater than 2, the production depletion time of the target well is 50-55 months. When p m p n When the absolute value of the difference is less than or equal to 2, if the curve shape of the second model is S-shaped, then the production exhaustion time of the target production well is the production time corresponding to the second inflection point of the curve of the second model. When p m p n If the absolute value of the difference is less than or equal to 2, and the curve shape of the second model is not S-shaped, then the production depletion time of the target well is 40-45 months.

2. The method according to claim 1, wherein, The production time corresponding to the second inflection point of the curve in the second model is determined in the following way: Obtain the second derivative of the second model and determine its value as -2 × 10⁻⁶. -5 to -6×10 -5 The production time corresponding to the second inflection point of the curve in the second model is the production time corresponding to the second inflection point.

3. The method according to claim 1, wherein, The difference between N and M is 5-8.

4. The method according to claim 3, wherein, The difference between N and M is 5.

5. The method according to any one of claims 1, 3, and 4, wherein, The value of M is not less than 10, and the value of N is not less than 15.

6. The method according to claim 1, wherein, The cumulative fluid production data of the target production well from the ignition time of the gas injection well during vertical well planar fire flooding includes: Acquire the cumulative production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process; The cumulative production data of the target production well from the ignition time of the gas injection well is corrected to obtain the cumulative production data of the target production well from the ignition time of the gas injection well.

7. The method according to claim 6, wherein, The correction of the cumulative production data of the target production well from the ignition time of the self-injection well is performed using the following formula: In the formula, Q 真实 Q represents the corrected cumulative product volume. 现场 This refers to the cumulative liquid production volume on-site. This is the correction factor.

8. The method according to claim 7, wherein, The value ranges from 1.1 to 1.

2.

9. A method for determining the position of the combustion front during a vertical well planar fire drive process, wherein, The method includes: Acquire the cumulative fluid production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process; Based on the cumulative production data of the target production well from the ignition time of the injection well, a third model was obtained; the third model is a calculation model for the cumulative production volume with respect to production time, and the third model is as follows: In the formula, y is the cumulative liquid production volume; x is the cumulative liquid production time; A1, A2, x0, and p are all coefficients; Using the third model, determine the cumulative production volume corresponding to the target cumulative production time of the target production well; Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, determine the average advance speed of the fire line in the direction from the gas injection well to the target production well within the target cumulative production time. Based on the average advance velocity of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time, the position of the combustion front of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined. Where the injection-production well network where the target production well is located is a single injection-multiple production network, the average advance speed of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined based on the cumulative production volume corresponding to the target cumulative production time of the target production well. This includes: Obtain the average width and average thickness of the fire chamber corresponding to the target cumulative liquid production time; Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, the average width of the fire chamber expansion, and the average thickness of the fire chamber, the average advance speed of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined. Where the injection-production well network where the target production well is located is a single injection-single production network, the average advance speed of the gas injection well to the target production well in the direction of the target production well within the target cumulative production time is determined based on the cumulative production volume corresponding to the target cumulative production time of the target production well. This includes: Obtain a first velocity ratio; wherein the first velocity ratio is the ratio of the average advance velocity of the fire line to the average movement velocity of the formation fluid; Based on the cumulative production volume corresponding to the target cumulative production time of the target production well, determine the average formation fluid migration velocity corresponding to the target cumulative production time of the target production well. Based on the average formation fluid movement velocity corresponding to the target cumulative production time of the target production well, and combined with the first velocity ratio, the average advance velocity of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined.

10. The method according to claim 9, wherein, The cumulative fluid production data of the target production well from the ignition time of the gas injection well during vertical well planar fire flooding includes: Acquire the cumulative production data of the target production well from the moment of ignition of the gas injection well during the vertical well planar fire drive process; The cumulative production data of the target production well from the ignition time of the gas injection well is corrected to obtain the cumulative production data of the target production well from the ignition time of the gas injection well.

11. The method according to claim 10, wherein, The correction of the cumulative production data of the target production well from the ignition time of the self-injection well is performed using the following formula: In the formula, Q 真实 Q represents the corrected cumulative product volume. 现场 This refers to the cumulative liquid production volume on-site. This is the correction factor.

12. The method according to claim 11, wherein, The value ranges from 1.1 to 1.

2.

13. The method according to claim 9, wherein, The average advance rate of the fire line in the direction from the gas injection well to the target production well during the target cumulative production time is determined by the following formula: In the formula, The average advance speed on the front line, in m / d; Cumulative product volume, in m³ 3 b represents the average width of the fire chamber, in meters. h represents the average thickness of the fire chamber, in meters (m). Accumulated production time for the target product, in days (d).

14. The method according to claim 9 or 13, wherein, When the fire line advances from the gas injection well to the target production well, and the fire line does not cover the top of the reservoir, the average thickness of the fire chamber is determined based on half the thickness of the perforated section of the gas injection well; wherein, the average thickness of the fire chamber is 0.7-0.8 times half the thickness of the perforated section of the gas injection well. When the fire line advances from the injection well to the target production well and extends beyond the top of the reservoir, the average thickness of the fire chamber is determined by multiplying the distance from the injection well to the target production well and the ratio of the distance between the fire line extending beyond the top of the reservoir and the injection well to the distance between the injection well and the perforated section thickness of the injection well; wherein, the average thickness of the lower fire chamber is 0.5-0.8 times the product. The average expansion width of the fire chamber is determined based on half the distance between the target production well and its adjacent wells; wherein the average expansion width of the fire chamber is 0.8-0.9 times half the distance between the target production well and its adjacent wells.

15. The method according to claim 9, wherein, Obtaining the first velocity ratio includes: To obtain formation permeability and oil saturation; Determine the first velocity ratio corresponding to formation permeability and oil saturation.

16. The method according to claim 15, wherein, Determining the first velocity ratio corresponding to formation permeability and oil saturation includes: Through indoor one-dimensional combustion tube fire-driven experiments under formation permeability and oil saturation conditions, the first velocity ratio corresponding to formation permeability and oil saturation was determined.

17. The method according to claim 9 or 15, wherein, The first speed ratio is 1.5-3.

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