Method and equipment for inhibiting top water from leaking

Abstract

The embodiment of the invention provides a method and equipment for restraining top water from leaking. The method comprises the steps that an injection-production well pattern is arranged below a top water layer; the injection-production well pattern and the oil layer are preheated, so that the oil layer is preheated to the expected temperature, thermal communication is formed between the injection-production wells, an oxidizing medium is injected into the injection-production well pattern, in-situ crude oil is oxidized, an interlayer is formed, and the interlayer is located between the top water layer and the oil layer and used for isolating the top water layer from the oil layer; and associated gas generated by oxidizing the crude oil in the stratum is discharged through the injection-production well pattern, the amount of the discharged associated gas is detected, and the heat tracing temperature and the parameters of the injected oxidizing medium are adjusted according to the associated gas amount and components thereof. According to the method, top water drainage is effectively inhibited, and the oil reservoir development effect is improved.

Description

Technical Field

[0001] The invention relates to the field of oil production, and in particular to a method and a device for suppressing top water leakage. Background Art

[0002] Heavy oil air injection development technology is an important successor technology for heavy oil development. This technology has the advantages of rich resources, low cost and wide adaptability. Heavy oil air injection is mainly used in fire drive development of heavy oil reservoirs, and the combustion method is mainly high-temperature oxidation. Fire drive development technology is to continuously inject air into the oil layer through the gas injection well and ignite the oil layer, forming a high-temperature combustion front with a stable expansion of more than 450°C in the reservoir, thereby pushing the formation crude oil from the gas injection well to the production well. In recent years, heavy oil air injection technology has been applied to auxiliary steam huff and puff, auxiliary steam drive and other aspects. This technology has been widely used because it is suitable for a wide range of reservoir types, the injected medium air is not affected by the environment and climate, is easy to obtain, and the components are stable, efficient and economical.

[0003] For example, heavy oil and oil sands are developed through SAGD (Steam Assisted Gravity Drainage) technology. This technology injects steam into the reservoir from a vertical well or a horizontal well above the horizontal production well near the bottom of the reservoir, so that the heated crude oil and steam condensate are produced from the horizontal well at the bottom of the reservoir. In the process of developing top water reservoirs using SAGD, the steam cavity gradually expands. When the front of the steam cavity approaches the top water layer, it is easy for the water layer to connect with the steam cavity. The top water penetrates downward or even leaks under the action of the pressure difference, which seriously affects the SAGD production effect and even makes the SAGD unable to continue operating.

[0004] To address the problem of top water leakage, existing technologies generally reserve a certain thickness at the top of the oil layer as a "barrier" to slow down the invasion of top water (the thickness of the oil layer to avoid top water on site is generally 40 to 50 meters). This method sacrifices the movable volume of the reservoir and reduces the movable reserves of the reservoir. In addition, once water invasion trends appear during the mining process, the production area will be closed. Summary of the invention

[0005] The purpose of the embodiment of the present invention is to provide a method and device for suppressing top water leakage, which are used for oil production. The method effectively suppresses top water leakage and improves the effect of oil reservoir development.

[0006] In order to achieve the above object, an embodiment of the present invention provides a method for suppressing top water leakage for oil production, the method comprising:

[0007] Setting up an injection and production well network under the top water layer;

[0008] Preheating the injection-production well network and the oil layer to preheat the oil layer to a desired temperature and form thermal connectivity between the injection-production wells, and injecting an oxidizing medium into the injection-production well network to oxidize the formation crude oil to form an interlayer, the interlayer being located between the top water layer and the oil layer to isolate the top water layer and the oil layer;

[0009] The associated gas generated by oxidizing the formation crude oil is discharged through the injection-production well network, the amount of the discharged associated gas is detected, and the heating temperature and the parameters of the injected oxidizing medium are adjusted according to the amount of the associated gas and its components.

[0010] Optionally, adjusting the heating temperature and the parameters of injecting the oxidizing medium according to the amount and composition of the associated gas includes:

[0011] When the associated gas volume is lower than the associated gas threshold, and the oxygen content in the components is greater than the oxygen threshold, and the carbon dioxide content is less than the carbon dioxide threshold, the heating temperature is increased, and / or the conditions for injecting the oxidizing medium are adjusted;

[0012] The parameters of injecting the oxidizing medium include at least gas injection speed, gas injection intensity, gas injection volume and oxidizing medium temperature.

[0013] Optionally, the preheating treatment and the heating temperature adjustment method include steam heating and / or electric heating;

[0014] The steam heating includes: determining the total amount of injected steam by total injected heat, heat loss of injection-production well network, and heat loss of oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam.

[0015] Optionally, the method further includes:

[0016] The injection and production mode is adjusted according to the amount of associated gas and its components, and the injection and production mode includes continuous injection and intermittent injection.

[0017] Optionally, the injection-production well network includes a plurality of injection-production wells, and the injection-production wells are horizontal wells or vertical wells;

[0018] The barrier layer is located below the top water layer.

[0019] Optionally, the oxidizing medium is a medium for low-temperature oxidation of heavy oil, and the low temperature is 90°C to 170°C.

[0020] Optionally, the method further includes: when the amount of associated gas in the injection-production well network is lower than an associated gas threshold, oxidizing the formation crude oil in adjacent wells.

[0021] On the other hand, the present invention provides a device for suppressing top water leakage for oil production, the device comprising:

[0022] A preheating device, used for preheating the injection-production well network and the oil layer, used for preheating the oil layer to a desired temperature and forming thermal connection between the injection-production wells, wherein the injection-production well network is located below the top water layer;

[0023] An injection device, used for injecting an oxidizing medium to oxidize the formation crude oil to form a barrier layer, wherein the barrier layer is located between the top water layer and the oil layer and is used for isolating the top water layer and the oil layer;

[0024] The controller is used to detect the amount of associated gas discharged through the injection and production well network, and adjust the heating temperature and the parameters of the injected oxidizing medium according to the amount of associated gas and its components.

[0025] Optionally, adjusting the heating temperature and the parameters of injecting the oxidizing medium according to the amount and composition of the associated gas includes:

[0026] When the associated gas volume is lower than the associated gas threshold, and the oxygen content in the components is greater than the oxygen threshold, and the carbon dioxide content is less than the carbon dioxide threshold, the heating temperature is increased, and / or the conditions for injecting the oxidizing medium are adjusted;

[0027] The parameters of injecting the oxidizing medium include at least gas injection speed, gas injection intensity, gas injection volume and oxidizing medium temperature.

[0028] Optionally, the preheating treatment and the heating temperature adjustment method include steam heating and / or electric heating;

[0029] The steam heating includes: determining the total amount of injected steam by total injected heat, heat loss of injection-production well network, and heat loss of oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam.

[0030] Optionally, the controller is also used to adjust the injection and production mode according to the amount of associated gas and its components, and the injection and production mode includes continuous injection and intermittent injection.

[0031] Optionally, the injection-production well network includes multiple injection-production wells, and the injection-production wells are horizontal wells or vertical wells.

[0032] Optionally, the barrier layer is located below the top water layer.

[0033] Optionally, the controller is also used to adjust the injection and production mode according to the amount of associated gas and its components, and the injection and production mode includes continuous injection and intermittent injection.

[0034] Optionally, the injection-production well network includes multiple injection-production wells, and the injection-production wells are horizontal wells or vertical wells.

[0035] Optionally, the barrier layer is located below the top water layer.

[0036] Optionally, the oxidizing medium is a medium for low-temperature oxidation of heavy oil; the low temperature is 90°C to 170°C.

[0037] Optionally, the equipment further comprises an auxiliary device for oxidizing the formation crude oil of adjacent wells when the amount of associated gas in the injection-production well network is lower than an associated gas threshold.

[0038] A method for inhibiting top water leakage of the present invention is used for oil production, and the method includes: setting an injection-production well network under the top water layer; preheating the injection-production well network and the oil layer to preheat the oil layer to the expected temperature and form thermal connection between the injection-production wells; and injecting an oxidizing medium into the injection-production well network to oxidize the formation crude oil to form an interlayer, the interlayer is located between the top water layer and the oil layer, and is used to isolate the top water layer and the oil layer; the associated gas generated by oxidizing the formation crude oil is discharged through the injection-production well network, the amount of the discharged associated gas is detected, and the parameters of the preheating treatment and the injection of the oxidizing medium are adjusted according to the amount of the associated gas and its components. The present invention forms an injection-production well network in the top water development area and the top water leakage risk area, preheats the injection-production well network and the oil layer where it is located, and injects an oxidizing medium that effectively oxidizes the crude oil in the oil layer at low temperature, so that the injected oxidizing medium and the crude oil in the oil layer continue to undergo low-temperature oxidation reaction, forming a non-fluid high-viscosity heavy oil and coke deposition zone, enhancing the oil layer isolation capacity, inhibiting top water leakage, and improving the oil reservoir development effect.

[0039] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0041] Figure 1 It is a schematic flow diagram of a method for suppressing top water leakage of the present invention;

[0042] Figure 2 It is a schematic diagram of water avoidance in the existing top water reservoir when no oxidizing medium is injected;

[0043] Figure 3 It is a schematic diagram of water avoidance in a top water reservoir after low temperature oxidation by injecting an oxidizing medium according to the present invention;

[0044] Figure 4 This is a schematic diagram of the existing SAGD steam cavity development without air injection;

[0045] Figure 5 It is a schematic diagram of the development of the SAGD vapor cavity after injection of air for low temperature oxidation according to the present invention;

[0046] Figure 6 This is a comparison chart of crude oil viscosity after original, dynamic, and static low-temperature oxidation;

[0047] Figure 7 This is a schematic diagram of the temperature field of the normal SAGD profile when no air is injected;

[0048] Figure 8 The cross-sectional temperature field of the SAGD after air injection and low-temperature oxidation of the present invention;

[0049] Fig. 9 is a cross-sectional schematic diagram of a well pattern of a method 1 of the present invention;

[0050] Fig.10 is a plan view of a well pattern of a method 1 of the present invention;

[0051] Fig.11 is a cross-sectional schematic diagram of a well pattern of a second method of the present invention;

[0052] Fig.12 This is a plan view of a well pattern of a second method of the present invention;

[0053] Fig.13 It is a schematic cross-sectional view of the three-well network of the present invention;

[0054] Fig.14 It is a plan view of a three-well network of the method of the present invention;

[0055] Fig.15 This is a schematic diagram of the well layout method of the SAGD example of the present invention;

[0056] Fig.16 It is a schematic diagram of the heating zone of the present invention.

[0057] Description of Reference Numerals

[0058] 101 - top water layer;

[0059] 102-water-avoiding oil layer;

[0060] 103-mobilization area;

[0061] 104-high viscosity colloid-like heavy oil zone;

[0062] 105-steam chamber;

[0063] 106- asphalt shell;

[0064] 107- Newly added usable oil layer;

[0065] 201-Vertical production well;

[0066] 202-gas injection vertical well;

[0067] 203- Production horizontal well;

[0068] 204- Gas injection horizontal well. DETAILED DESCRIPTION

[0069] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0070] Ordinary heavy oil and extra heavy oil have a certain flowability under reservoir conditions. The original temperature of super heavy oil reservoirs is low (generally below 50°C), the crude oil viscosity is high, and there is basically no flowability under reservoir conditions. The properties of heavy oil are relatively stable, and it is difficult for oxidation and other reactions to occur under reservoir conditions.

[0071] Through research, the inventors found that the viscosity of crude oil increases after oxygenation reaction occurs during the low-temperature oxidation process, and it becomes more difficult to flow in the formation. When super-heavy oil is oxidized at low temperatures of 90°C to 170°C, the viscosity of the crude oil increases linearly and the increase rate gradually increases; analysis of crude oil components shows an increase in asphaltene and non-hydrocarbon content, and even non-hydrocarbon deposition; and the dynamic low-temperature oxidation viscosity-increasing effect is significantly better than the static low-temperature oxidation effect under the same conditions. The indoor fluidity of the colloidal heavy oil formed by dynamic oxidation is that it cannot be melted at 100°C, it can be softened at 145°C, melted at 180°C, and can flow at 200°C. Figure 6 shown.

[0072] Figure 1 It is a schematic flow diagram of a method for suppressing top water leakage of the present invention, such as Figure 1 As shown, the method for suppressing top water leakage of the present invention is used for oil production, and the method comprises: step S101 is to set an injection-production well network under the top water layer, and the wells in the injection-production well network are thermally connected. The injection-production well network includes a plurality of injection-production wells, and the injection-production wells are horizontal wells or vertical wells. Figure 2 As shown, in the existing oil production, the unopened oil reservoir area includes a top water layer 101, a water-avoiding oil layer 102 and a producing layer 103. Specifically, the injection and production well network is arranged below the top water layer 101, and the injection and production well network is located above the water-avoiding oil layer 102.

[0073] The injection-production well pattern includes at least one of a horizontal well and a vertical well. According to a specific implementation method, the present application adopts a combination of horizontal and vertical wells to design three injection-production well patterns: Method 1 includes a production horizontal well 203, a gas injection vertical well 202 and a production vertical well 201 (such as Fig. 9 and Fig.10 Method 2 includes a gas injection horizontal well 204 and a production horizontal well 203 (as shown in Fig.11 and Fig.12 Method three includes a gas injection horizontal well 204, a production horizontal well 203 and a production vertical well 201 (as shown); Fig.13 and Fig.14 shown).

[0074] The spacing of the injection and production well network in the three methods needs to be determined comprehensively according to the crude oil properties of different oil reservoirs and their preheating range and other conditions. Preferably, the injection and production well networks are thermally connected. Among them, the number of wells in method one is relatively large, the investment is large, and the economic efficiency is relatively poor, but it is conducive to production regulation. The reaction speed and degree can be regulated by adjusting the injection and production wells and injection and production parameters, and the plane range, longitudinal thickness, and internal reaction product properties of the expected isolation zone are adjusted to be small, while ensuring its isolation performance; the number of wells in method two is small, the investment is small, and the economic efficiency is good, but due to the heterogeneity of the reservoir, the reaction degree in the double horizontal well control area is uneven, the products and properties are different, and the regulation after gas channeling is difficult; method three is to add production vertical wells (auxiliary production vertical wells) on the basis of method two, the investment is increased, but it is conducive to production regulation. By adjusting whether the auxiliary production wells produce gas, the gas production volume, the gas production speed, etc., the reaction speed, the reaction front advancement speed, etc., the isolation zone formation and its isolation performance can be ensured.

[0075] Step S102 is to preheat the injection-production well network and inject an oxidizing medium to oxidize the formation crude oil to form a barrier layer, which is located between the top water layer and the oil layer and is used to isolate the top water layer and the oil layer.

[0076] Specifically, the critical temperature conditions for low-temperature oxidation are different for different reservoir conditions and oil properties, and the degree of oxidation reaction is also different under different temperature conditions; but in general, under the original temperature conditions of heavy oil reservoirs, oxidation reaction is not easy to occur, so a certain amount of preheating is required to achieve the ideal low-temperature oxidation conditions for the target reservoir. According to the target reservoir conditions, steam injection, electric heating and other methods can be used to preheat the oil layer.

[0077] The preheating treatment and the method of adjusting the tracing temperature include steam heating and / or electric heating; the steam heating includes: determining the total amount of injected steam by the total amount of injected heat, the heat loss of the injection and production well network, and the heat loss of the oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam. The tracing temperature is usually higher than 100°C. When the tracing temperature is lower than 100°C, the temperature is increased, and when it is higher than 150°C, the temperature is reduced. The cooling method may include adding water, reducing the production rate, the gas injection rate, and stopping the gas injection.

[0078] The preheating parameters are mainly determined by a combination of methods such as physical simulation, reservoir numerical simulation and reservoir engineering calculation. Preferably, the preheating parameters of vertical well injection steam can be designed by steam throughput parameters, but the liquid production must be controlled. There are two ways to preheat horizontal wells: steam throughput cycle preheating and electric heating.

[0079] According to a specific implementation method, steam heating includes: first calculating the total heat required to heat the current oil layer temperature to the target oil layer temperature between the injection and production wells; then calculating the heat loss in the wellbore. For thermal production vertical wells and horizontal wells, the vertical well sections generally use insulated oil pipes plus nitrogen insulation (wellbore heat loss can be ignored). Compared with the horizontal well section, it is necessary to calculate the heat loss when the steam circulates in the horizontal well section, and use this as an approximation as the heat exchange amount between the steam and the formation, and convert the total heat required by the formation into steam injection. The details are as follows:

[0080] 1. Calculation of total heating includes:

[0081] Q 1 =π(R 2 -r 2 )h(1-φ)ρC(t 1 -t 0 ) (1)

[0082] Q 2 =π(R 2 -r 2 )hφS O ρ O C O ρC(t 1 -t 0 ) (2)

[0083] Q 3 =π(R 2 -r 2 )hφS w ρ w C w ρC(t 1 -t 0 ) (3)

[0084] ∑Q=Q 1 +Q 2 +Q 3 (4)

[0085]

[0086] Where, ∑Q is the total heating amount (kJ); Q 1 is the heat required to heat the rock within the preheating range to the preheating temperature (kJ); Q 2 Q is the heat required to heat the crude oil within the preheating range to the preheating temperature (kJ); 3 is the heat required to heat the water in the preheating range to the preheating temperature (kJ); R is the preheating radius of the oil layer (m); r is the outer radius of the oil layer casing (m); h is the length of the horizontal well section (m); t 1 is the preheating temperature (℃); t 0 is the current oil layer temperature (℃); C is the rock specific heat (J / (g.℃)); CO is the specific heat of crude oil (J / (g.℃)); Cw is the specific heat of water (J / (g.℃)), Cw=4.19J / (g.℃), φ is the porosity, ρ is the rock density (g / cm 3 ), S O is the oil saturation, ρ O is the density of crude oil, S w is water saturation, ρ w is the density of water, t 0 is the current temperature of the oil layer (degrees Celsius), γ O is the relative density of crude oil.

[0087] 2. Heat loss Q when steam circulates in the horizontal well section L :

[0088] The heat exchange amount when steam circulates in the horizontal section is converted according to the steam dryness loss. The ideal circulation preheating is that the steam injected has a dryness of 0 after returning to the heel through the toe of the horizontal well.

[0089] Firstly, the TWBS thermal wellbore numerical simulation software is used to simulate and calculate the temperature field, pressure field, and dryness field in the horizontal wellbore under different injection pressures and injection speeds, and the injection pressure and the steam dryness at the inlet and outlet of the horizontal section are determined based on the calculation results.

[0090] Secondly, use formulas (6) to (10) to calculate the steam enthalpy at the inlet and outlet of the horizontal section.

[0091] H w =4.095T+8.765×10 -4 T 2 T<240℃ (6)

[0092] H w =302+1.3T+7.315×10 -3 T 2 T≥240℃ (7)

[0093] L V =273×(374.15-T) 0.38 (8)

[0094] H s =X×L V +H w (9)

[0095] p s =(-175.776+2.29272T-0.0113953T 2 +2.6278×10 -5 T 3 -2.7326×10-8 T 4 +1.13816×10 -11 T 5 ) 2 (10)

[0097] Among them, H w is the enthalpy of saturated water (J / g); L V is the latent heat of vaporization (J / g); T is the saturation temperature (℃); H s is the steam enthalpy (J / g); X is the steam quality; p s is the saturation pressure (MPa).

[0098] Substituting the temperature and dryness at the inlet and outlet under the corresponding pressure into the above formula, the corresponding enthalpy value can be obtained. The difference between the inlet enthalpy and the outlet enthalpy is the enthalpy lost in the horizontal section.

[0099] 3. Calculate the heat loss Q of the oil layer in the non-target heating zone ne ,include:

[0100] like Fig.16 As shown, the target heating area of ​​the horizontal section is Re, and the heating radius of the horizontal section is R. When the oil layer is infinitely thick or the injected steam is limited and the steam does not reach the top and bottom boundaries, the heating area along the radial direction of the horizontal well is circular, and its instantaneous heat balance equation is:

[0101]

[0102] By integrating the above formula, we can get:

[0103]

[0104] Then we have:

[0105]

[0106] The volume of the non-target heating zone is equivalent to the radius The volume of the cylinder with a length equal to the length of the horizontal section, and the heat consumed is the heat required to heat the volume from the original reservoir temperature to the target temperature of the target heating zone, which can be calculated by formulas (1) to (5) and (12) to (13).

[0107] In the formula, i s is the steam mass injection rate (kg / h), h m is the enthalpy of saturated water vapor (kJ / kg), M r is the heat capacity of the oil layer (kJ / (m3.℃)), T R is the original oil layer temperature (℃), T s is the injection steam temperature (°C), T eis the target temperature of the target heating zone, L is the length of the horizontal section of the horizontal well, t inj is the steam injection time (hours).

[0108] 4. Calculate the heat Q required to heat the oil layer in the target heating zone e ,include:

[0109] The radius of the target heating zone is R e , using formulas (1) to (5), the heat required to heat the zone to the target temperature Q can be calculated e .

[0110] 5. Calculate the steam injection volume and injection time, including:

[0111] Total amount of steam to be injected:

[0112] Q 总 =Q L +Q e +Q ne +∑Q (14)

[0113] According to the above calculation of the required heat and the thermal properties of steam, calculate the amount of steam injected q inj .

[0114] Steam injection time:

[0115] t inj =q inj / v inj (15)

[0116] Among them, v inj is the steam injection rate. If electric heating is used, the total heat required is calculated according to the above method, and the heating time is determined according to the output power of the heating cable using formulas (1) to (14).

[0117] t ele =Q 总 / P (16)

[0118] Where P is the output power of the heating cable (kJ / d).

[0119] The injection-production well network is preheated and an oxidizing medium is injected to oxidize the formation crude oil to form a barrier layer, which is located between the top water layer and the oil layer and is used to isolate the top water layer and the oil layer. The oxidizing medium is a medium for low-temperature oxidation of heavy oil; the low temperature is 90°C to 170°C. The barrier layer is located below the top water layer.

[0120] Preferably, the oxygen consumption of low-temperature oxidation ranges from 1 / 6 to 1 / 3 of the oxygen consumption of conventional fire drive, and the gas injection rate of the target reservoir can be determined based on the oxygen consumption. Under different crude oil properties and reservoir conditions, the conditions and intensity of the oxidation reaction are different, and the resulting isolation effect is also different. In order to ensure the implementation effect, physical simulation and reservoir numerical simulation optimization research should be carried out in the early stage to obtain more reasonable parameters. During the on-site implementation, temperature, pressure, and associated gas components should be monitored, and the injection and production parameters should be adjusted in time to ensure that the low-temperature oxidation is carried out continuously and effectively.

[0121] Specifically, the oxidizing medium is air (hot air), oxygen-enriched air, oxygen-reduced air and other media that can effectively oxidize crude oil at low temperature, and it can also include catalyst oxidants and other composite additives to promote low-temperature oxidation. At the same time, to ensure the effect of low-temperature oxidation reaction, when the temperature and pressure of the oil layer are too high or too low, appropriate media and other technical means can be injected to ensure the continuous and effective reaction, such as water injection for cooling, steam heating, nitrogen insulation and pressurization, and adjustment of injection parameters.

[0122] The barrier layer is located between the top water layer and the newly added movable oil layer 107, and is used to isolate the top water layer 101 and the newly added movable oil layer 107. Specifically, the high viscosity colloid-like heavy oil zone 104 is the barrier layer. Figure 2 and Figure 4 shown.

[0123] In order to achieve a better isolation effect and release more water-avoiding thickness, preferably, the wells that need to be heated (i.e., production vertical wells and / or production horizontal wells, i.e., gas injection wells in the injection-production well network) are deployed under the top water (which can also be the asphalt shell 106), and it is predicted that a high-viscosity colloid heavy oil zone of about 10m will be formed, and at least 20m of water-avoiding oil layer thickness will be released. Due to the overburden effect of gas and later regulation, the vertical wells are set in the corresponding layer section, and the distance between the perforation top boundary and the top water (which can also be the asphalt shell 106) is 1 / 2 to 2 / 3 of the thickness between the horizontal well and the asphalt shell 106. In order to continuously cause low-temperature oxidation reaction, the well connection temperature after preheating is >100°C, and the production-injection ratio is about 1.0.

[0124] Step S103 is to discharge the associated gas generated by oxidizing the formation crude oil through the injection-production well network, detect the amount of the discharged associated gas, and adjust the heating temperature and the parameters of the injected oxidizing medium according to the amount of the associated gas and its components. Heating is heating the pipeline that transmits the production logistics or samples. In the present invention, the adjustment of the heating temperature is mainly used to promote the oxidation reaction.

[0125] Specifically, the heating temperature and the parameters for injecting the oxidizing medium are adjusted according to the associated gas amount and its components, including: when the associated gas amount is lower than the associated gas threshold, and the oxygen content in the components is greater than the oxygen threshold, and the carbon dioxide content is less than the carbon dioxide threshold, the heating temperature is increased, and / or the conditions for injecting the oxidizing medium are adjusted; the parameters for injecting the oxidizing medium include at least the injection speed, injection intensity, injection volume and oxidizing medium temperature. Among them, the associated gas threshold, oxygen threshold and carbon dioxide threshold are all determined according to actual conditions. For example, when the associated gas amount is lower than 1 / 2 to 1 / 3 of the original discharge amount, or when the oxygen content in the associated gas components increases to a certain threshold and the carbon dioxide content decreases to a certain threshold, the heating temperature is increased.

[0126] The present application also includes: adjusting the injection and production mode according to the associated gas volume and its components, and the injection and production mode includes continuous injection and intermittent injection. Specifically, the gas injection mode includes continuous injection and intermittent injection. The gas injection parameters include gas injection speed, gas injection intensity, gas injection volume, injection temperature, etc. The produced parameters include gas production, liquid production, production-injection ratio, etc.

[0127] In order to ensure the implementation effect, physical simulation and reservoir numerical simulation optimization research should be carried out in the early stage to obtain more reasonable parameters. During the on-site implementation, temperature, pressure and associated gas components should be monitored, and injection and production parameters should be adjusted in time to ensure that low-temperature oxidation is carried out continuously and effectively.

[0128] The present invention also proposes a specific implementation method, firstly, the horizontal well uses steam circulation or electric heating to preheat the oil layer until the temperature of the preheated oil layer section reaches 100°C to 150°C (i.e., reaches a better low-temperature oxidation temperature condition), and the oil layer near the top water (which can also be asphalt shell) is basically in the original state. Then, the oxidizing medium is continuously injected from above the horizontal section of the injection vertical well to react with the formation crude oil at a low temperature. The associated gas generated is mainly produced through the production vertical well, and the horizontal well can assist in the production of associated gas, or adjacent horizontal wells form an injection and production well network, and the vertical well can assist in the production of associated gas.

[0129] In order to ensure the degree of low-temperature oxidation reaction between injection and production wells, when the gas production of horizontal wells is greatly reduced (less than 1 / 2 to 1 / 3 of the original displacement), it is possible to consider exchanging the injection and production wells of adjacent wells so that the oil layer below the reaction zone (top water layer, which can also be the asphalt shell 106) and the oil layer below the horizontal well that reaches the connection temperature after preheating is expected to form a high-viscosity colloid-like heavy oil strip (such as Figure 3 and Figure 5As shown in the figure, the crude oil reacts more fully, which ensures that the horizontal well section and its upper oil layer continue to undergo dynamic low-temperature oxidation, and eventually forms a high-viscosity heavy oil and coke deposition zone with basically no flow ability below the top water; increasing the formation barrier capacity is equivalent to increasing the thickness of the "interlayer", so the thickness of the top water avoidance oil layer can be reduced and the recoverable reserves of the reservoir can be increased; for the area where the well is shut down due to top water leakage, production can be resumed appropriately to improve the regional production effect. It can reduce the risk of top water leakage, while releasing part of the original water avoidance thickness, expanding the swept volume of the steam chamber 105 (for example, oil reservoirs developed using SAGD), and improving the recovery factor (such as Figure 7 and Figure 8 shown).

[0130] At the same time, the changes in reservoir pressure and temperature can be analyzed and determined based on the temperature and pressure measurement data, and the low-temperature reaction of the reservoir can be analyzed based on the associated gas production and composition. When the gas production is significantly reduced (production-injection ratio <1 / 3), the reservoir pressure increases, the oxygen content in the associated gas continues to increase and remains relatively stable for a certain period of time, and the oxygen utilization rate continues to decrease and remains at a relatively stable low value (1 / 2-1 / 3 of normal oxidation) for a certain period of time (which can be determined comprehensively through the physical model experiment and numerical simulation research results of the target block), the process ends.

[0131] The present invention also proposes another specific implementation method. A certain oil reservoir is a top and bottom water super-heavy oil reservoir. There is no pure mudstone barrier between the oil layer and the surrounding water body, but the thickness of the asphalt shell at the oil-water interface is 0.5-2m, the average thickness of the oil layer is 77.0m, and the maximum thickness of the oil layer is 126.6m. Fig.15 The vertical well and horizontal well combination SAGD development is shown. The test area as a whole forms a large steam chamber located in the producing area 103. As the steam chamber expands, the top water leaks down, resulting in an increased risk of water breakthrough. Once water breakthrough occurs, SAGD cannot continue to operate.

[0132] Through indoor experiments, monitoring data and reservoir numerical analysis, it was determined that the top water layer of the reservoir is mainly composed of asphalt shell, which softens at 120°C and may be fluid at 160°C. When the pressure difference between the top water layer and the vapor chamber is greater than 1.5-2 MPa, the viscosity drops to 8×10 4 mPa·s, the top water layer is prone to breakthrough. In order to control the risk of top water leakage, vertical wells and horizontal wells, horizontal wells and horizontal wells are used in the top water area. Horizontal wells are deployed in the upper part of the oil layer and about 10m below the asphalt shell to form a horizontal well and horizontal well injection and production well network. Vertical wells can also be deployed between horizontal wells to form a vertical well and horizontal well injection and production well network with horizontal wells.

[0133] First, the horizontal well is preheated by steam circulation or electric heating, with a preheating radius of about 5m, so that the oil layer temperature reaches 100℃-150℃, that is, a good low-temperature oxidation temperature condition is achieved, and the vicinity of the asphalt shell is basically in the original state. It is calculated that when the horizontal section of the horizontal well is about 400m long and the heating radius is about 5m, when the oil layer is heated from the initial temperature to above 100℃, the heat required to be injected is 6.5×10 9 kJ, if circulating preheating is adopted, when the steam injection rate is 90t / d and the wellhead dryness is 95%, preheating is required for about 8 months. If electric heating of the entire well section is adopted, it takes 7-8 months.

[0134] Then, the vertical well is injected with 2×10 4 ~5×10 4 m 3 / d gas injection rate continuously injects air, and the oxygen in the injected air reacts with the formation crude oil at low temperature. The associated gas produced is mainly produced through vertical production wells, and horizontal wells can assist in producing associated gas. The production-injection ratio is about 1.0. Or adjacent horizontal wells form an injection-production well network with a gas injection rate of 1.5×10 4 ~3×10 4 m 3 / 100m / d, vertical wells assist in producing associated gas, and the production-injection ratio is about 1.0. In order to ensure the degree of low-temperature oxidation reaction between injection and production wells, when the gas production of the production horizontal well is greatly reduced, the injection and production wells of adjacent wells can be exchanged to make the crude oil reaction between the wells more complete. The above methods ultimately form a high-viscosity colloid-like heavy oil belt with a thickness of about 10m between the injection and production wells, which increases the formation barrier capacity and reduces the risk of top water leakage in the later stage of SAGD. At the same time, at least 20m of water-avoiding oil layers can be turned into movable oil layers, which not only effectively inhibits top water leakage, but also increases the movable reserves, and is expected to increase the recovery rate by about 10%.

[0135] A method for inhibiting top water leakage of the present invention comprises: setting an injection-production well network under the top water layer, wherein the wells in the injection-production well network are thermally connected; preheating the injection-production well network and injecting an oxidizing medium to oxidize the formation crude oil to form an interlayer, wherein the interlayer is located between the top water layer and the oil layer and is used to isolate the top water layer and the oil layer; discharging the associated gas generated by oxidizing the formation crude oil through the injection-production well network, detecting the amount of the discharged associated gas, and adjusting the parameters of the preheating treatment and injection of the oxidizing medium according to the amount of the associated gas and its components. The present invention forms an injection-production well network in the top water development area and the top water leakage risk area, preheats the injection-production well network and the oil layer in which it is located, and injects an oxidizing medium into the injection-production well network that effectively oxidizes the crude oil in the oil layer at low temperature, so that the injected oxidizing medium and the crude oil in the oil layer continue to undergo low-temperature oxidation reaction, forming a non-fluid, high-viscosity heavy oil and a coke deposition zone, thereby enhancing the oil layer isolation capacity, inhibiting top water leakage, and improving the reservoir development effect. This method plays an important role in suppressing the communication between the steam cavity and the top water and further expanding the volume of the steam cavity for top water reservoirs implementing SAGD. It increases the available reserves and improves the development effect of the reservoir (not limited to the development of top water reservoirs using SAGD).

[0136] On the other hand, the present invention also provides a device for suppressing the leakage of top water, which is used for oil production. The device includes: a preheating device, which is used to preheat the injection and production well network, wherein the injection and production well network is located below the top water layer, and the wells in the injection and production well network are thermally connected; an injection device, which is used to inject an oxidizing medium to oxidize the formation crude oil to form a barrier layer, wherein the barrier layer is located between the top water layer and the oil layer and is used to isolate the top water layer and the oil layer; a controller, which is used to detect the amount of associated gas discharged through the injection and production well network, and adjust the parameters of the preheating treatment and the injection of the oxidizing medium according to the amount of associated gas and its components.

[0137] The parameters of the preheat treatment and the injection of the oxidizing medium are adjusted according to the amount of associated gas and its components, including: when the amount of associated gas is lower than the associated gas threshold, and the oxygen content in the components is greater than the oxygen threshold, and the carbon dioxide content is less than the carbon dioxide threshold, then the temperature of the preheat treatment is lowered, and / or the conditions for injecting the oxidizing medium are adjusted; the parameters for injecting the oxidizing medium include at least the injection rate, the injection intensity, the injection amount and the oxidizing medium temperature.

[0138] The preheating treatment includes steam heating and / or electric heating; the steam heating includes: determining the total amount of injected steam by the total amount of injected heat, the heat loss of the injection and production well network, and the heat loss of the oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam. The controller is also used to adjust the injection and production mode according to the amount of associated gas and its components, and the injection and production mode includes continuous injection and intermittent injection.

[0139] The injection-production well network includes at least one of a horizontal well and a vertical well; the barrier layer is located below the top water layer. The oxidizing medium is a medium for low-temperature oxidation of heavy oil; the low temperature is 90°C to 170°C.

[0140] Specifically, the critical temperature conditions for low-temperature oxidation are different for different reservoir conditions and oil properties, and the degree of oxidation reaction is also different under different temperature conditions; but in general, under the original temperature conditions of heavy oil reservoirs, oxidation reaction is not easy to occur, so a certain amount of preheating is required to achieve the ideal low-temperature oxidation conditions for the target reservoir. According to the target reservoir conditions, steam injection, electric heating and other methods can be used to preheat the oil layer.

[0141] The preheating treatment includes steam heating and / or electric heating; the steam heating includes: determining the total amount of injected steam by the total heat injected, the heat loss of the injection-production well network, and the heat loss of the oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam.

[0142] The preheating parameters are mainly determined by a combination of methods such as physical simulation, reservoir numerical simulation and reservoir engineering calculation. Preferably, the preheating parameters of vertical well steam injection can be designed by steam throughput parameters, but the liquid production must be controlled; the horizontal well circulation preheating can be preheated by electric heating.

[0143] According to a specific implementation method, steam heating includes: firstly calculating the total heat required to heat the oil layer from the current oil layer temperature to the target oil layer temperature between the injection and production wells; then calculating the heat loss in the wellbore. For the vertical well section of the thermal production vertical well and horizontal well, insulated oil pipes plus nitrogen insulation are generally used (wellbore heat loss can be ignored). Compared with the horizontal section of the horizontal well, it is necessary to calculate the heat loss when the steam circulates in the horizontal well section, and use this as an approximation as the heat exchange amount between the steam and the formation, and convert the total heat required by the formation into the steam injection amount.

[0144] Preferably, the oxygen consumption of low-temperature oxidation ranges from 1 / 6 to 1 / 3 of the oxygen consumption of conventional fire drive, and the gas injection rate of the target reservoir can be determined based on the oxygen consumption. Under different crude oil properties and reservoir conditions, the conditions and intensity of the oxidation reaction are different, and the resulting isolation effect is also different. In order to ensure the implementation effect, physical simulation and reservoir numerical simulation optimization research should be carried out in the early stage to obtain more reasonable parameters. During the on-site implementation, temperature, pressure, and associated gas components should be monitored, and the injection and production parameters should be adjusted in time to ensure that the low-temperature oxidation is carried out continuously and effectively.

[0145] Specifically, the oxidizing medium is air (hot air), oxygen-enriched air, oxygen-reduced air and other media that can effectively oxidize crude oil at low temperature, and it can also include catalyst oxidants and other composite additives to promote low-temperature oxidation. At the same time, to ensure the effect of low-temperature oxidation reaction, when the temperature and pressure of the oil layer are too high or too low, appropriate media and other technical means can be injected to ensure the continuous and effective reaction, such as water injection for cooling, steam heating, nitrogen insulation and pressurization, and adjustment of injection parameters.

[0146] The equipment forms an injection-production well network in the top water development area and the top water leakage risk area, preheats the gas injection well network and the oil layer in which it is located, and injects an oxidizing medium into the injection-production well network to effectively oxidize the crude oil in the oil layer at low temperature, so that the injected oxidizing medium and the crude oil in the oil layer continue to undergo low-temperature oxidation reaction, forming non-flowing high-viscosity heavy oil and coke deposition zones, enhancing the oil layer isolation capacity, inhibiting top water leakage, and improving the effect of oil reservoir development.

[0147] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0148] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0149] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0150] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A method for suppressing top water leakage for oil production, characterized in that: The method includes: Setting up an injection and production well network under the top water layer; Preheating the injection-production well network and the oil layer to preheat the oil layer to a desired temperature and form thermal connectivity between the injection-production wells, and injecting an oxidizing medium into the injection-production well network to oxidize the formation crude oil to form an interlayer, the interlayer being located between the top water layer and the oil layer to isolate the top water layer and the oil layer; The associated gas generated by oxidizing the formation crude oil is discharged through the injection-production well network, the amount of the discharged associated gas is detected, and the heating temperature and the parameters of the injected oxidizing medium are adjusted according to the amount of the associated gas and its components.

2. The method according to claim 1, characterized in that The step of adjusting the heating temperature and the parameters of injecting the oxidizing medium according to the associated gas amount and its components includes: When the amount of associated gas is lower than the associated gas threshold, the oxygen content in the components is greater than the oxygen threshold, and the carbon dioxide content is less than the carbon dioxide threshold, the heating temperature is increased, and / or the conditions for injecting the oxidizing medium are adjusted.

3. The method according to claim 2, characterized in that The parameters of injecting the oxidizing medium include at least gas injection speed, gas injection intensity, gas injection volume and oxidizing medium temperature.

4. The method according to claim 1, characterized in that: The preheating treatment and the heating temperature adjustment method include steam heating and / or electric heating.

5. The method according to claim 4, characterized in that The steam heating includes: determining the total amount of injected steam by total injected heat, heat loss of injection-production well network, and heat loss of oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam.

6. The method according to claim 1, characterized in that The method further includes: The injection and production mode is adjusted according to the amount of associated gas and its components, and the injection and production mode includes continuous injection and intermittent injection.

7. The method according to claim 1, characterized in that The injection-production well network includes a plurality of injection-production wells, and the injection-production wells are horizontal wells or vertical wells.

8. The method according to claim 1, characterized in that The barrier layer is located below the top water layer.

9. The method according to claim 1, characterized in that: The oxidizing medium is a medium for low-temperature oxidation of heavy oil; the low temperature is 90°C to 170°C.

10. The method according to claim 1, characterized in that The method further includes: When the amount of associated gas in the injection-production well network is lower than the associated gas threshold, the formation crude oil in the adjacent wells is oxidized.

11. A device for suppressing top water leakage, used in oil production, characterized in that: The equipment includes: A preheating device, used for preheating the injection-production well network and the oil layer, used for preheating the oil layer to a desired temperature and forming thermal connection between the injection-production wells, wherein the injection-production well network is located below the top water layer; An injection device, used for injecting an oxidizing medium to oxidize the formation crude oil to form a barrier layer, wherein the barrier layer is located between the top water layer and the oil layer and is used for isolating the top water layer and the oil layer; The controller is used to detect the amount of associated gas discharged through the injection and production well network, and adjust the heating temperature and the parameters of the injected oxidizing medium according to the amount of associated gas and its components.

12. The device according to claim 11, characterized in that The step of adjusting the heating temperature and the parameters of injecting the oxidizing medium according to the associated gas amount and its components includes: When the amount of associated gas is lower than the associated gas threshold, the oxygen content in the components is greater than the oxygen threshold, and the carbon dioxide content is less than the carbon dioxide threshold, the heating temperature is increased, and / or the conditions for injecting the oxidizing medium are adjusted.

13. The device according to claim 12, characterized in that The parameters of injecting the oxidizing medium include at least gas injection speed, gas injection intensity, gas injection volume and oxidizing medium temperature.

14. The device according to claim 11, characterized in that The preheating treatment and the heating temperature adjustment method include steam heating and / or electric heating.

15. The device according to claim 14, characterized in that The steam heating includes: determining the total amount of injected steam by total injected heat, heat loss of injection-production well network, and heat loss of oil layer, and determining the steam injection time according to the total amount of injected steam and the thermal properties of steam.

16. The device according to claim 11, characterized in that The controller is also used to adjust the injection and production mode according to the amount of associated gas and its components, and the injection and production mode includes continuous injection and intermittent injection.

17. The device according to claim 11, characterized in that The injection-production well network includes a plurality of injection-production wells, and the injection-production wells are horizontal wells or vertical wells.

18. The device according to claim 11, characterized in that The barrier layer is located below the top water layer.

19. The device according to claim 11, characterized in that The oxidizing medium is a medium for low-temperature oxidation of heavy oil; the low temperature is 90°C to 170°C.

20. The device according to claim 11, characterized in that The equipment also includes an auxiliary device for oxidizing the formation crude oil of adjacent wells when the amount of associated gas in the injection-production well network is lower than the associated gas threshold.

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