Method and device for inhibiting bottom water coning through crude oil in-situ oxidation

Abstract

The invention discloses a method and device for inhibiting bottom water coning through crude oil in-situ oxidation, and the method comprises the steps that oil layers at the bottoms of a bottom water development area and a bottom water coning area are preheated to a preset oxidation temperature, and preheated oil layers are obtained; an oxidizing medium is continuously injected into the preheated oil layer, so that the oxidizing medium and crude oil of the preheated oil layer are subjected to oxidation reaction, a packing layer is formed above the interface of the bottom water area and the oil layer, the oil layer packing capacity is enhanced, the thickness of the water-avoiding oil layer is reduced, the movable reserve volume is effectively increased, bottom water coning can be inhibited for a long time, and the oil layer is protected. The oil reservoir development effect is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of crude oil extraction, and specifically relates to a method and device for inhibiting bottom water coning by in-situ oxidation of crude oil. Background Art

[0002] In crude oil production, heavy oil air injection development technology has technical advantages such as rich resources, low cost and wide adaptability, and occupies an important position in heavy oil development. 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. However, high-temperature oxidation increases the fluidity of crude oil, which is easy to cause bottom water cone entry. Once the bottom water cones in, the production wells near the cone well need to be shut down, affecting the effect of reservoir development.

[0003] In the existing heavy oil reservoir development process, sufficient water avoidance thickness is generally reserved in advance to delay the coning of bottom water, but the available reserves of the reservoir are sacrificed. Once the bottom water coning trend appears during the production process, the production in the area is stopped, and then nitrogen injection or nitrogen + foaming agent is used to pressurize the coning bottom water to a suitable height. However, due to the difference in density, viscosity and mobility between the injected medium and the bottom water, it is easy to cause it to float and advance, which makes it easy to cause the bottom water to rise rapidly when the well is opened for production after the injection is completed, and the effective period is short. Summary of the invention

[0004] In order to solve the technical problems that sufficient water avoidance thickness is reserved to delay bottom water coning, which sacrifices the available reserves of the reservoir, and the effective period of bottom water coning by nitrogen injection or nitrogen + foaming agent is short, the present application provides a method and device for inhibiting bottom water coning by in-situ oxidation of crude oil.

[0005] In a first aspect, the present application provides a method for inhibiting bottom water coning by in-situ oxidation of crude oil, comprising:

[0006] Preheating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature to obtain a preheated oil layer;

[0007] An oxidizing medium is continuously injected into the preheated oil layer, so that the oxidizing medium undergoes an oxidation reaction with the crude oil in the preheated oil layer, so as to form a sealing layer above the interface between the bottom water zone and the oil layer.

[0008] In some embodiments, preheating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature includes: injecting steam or electric heating into the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to heat its temperature to the preset oxidation temperature.

[0009] In some embodiments, the total heat required to heat the temperature to the preset oxidation temperature is calculated as: Q 总 =Q L +Q e +Q ne , where Q L is the heat loss of steam when it circulates in the well, kJ, Q e The heat required to heat the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone, Q ne The heat required to heat the oil layer other than the preheated oil layer; the time required to heat to the preset oxidation temperature t = Q is obtained by the total heat and the heating rate 总 / P, where t is time, h, and P are heating rates.

[0010] In some embodiments, the preset oxidation temperature is 100-150°C.

[0011] In some embodiments, the oxidizing medium is air, hot air, oxygen-enriched air, oxygen-reduced air, and other media that react with crude oil for oxidation.

[0012] In some embodiments, the oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer, including: the oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to obtain a mixture of colloid-like heavy oil, coke and asphaltene sediments, and the mixture forms a sealing layer above the interface between the bottom water zone and the oil layer.

[0013] In some embodiments, the continuously injecting oxidizing medium into the preheated oil layer so that the oxidizing medium undergoes an oxidation reaction with the crude oil in the preheated oil layer includes: injecting a catalyst, an oxidant and a composite auxiliary agent while injecting the oxidizing medium to promote the oxidation reaction.

[0014] In a second aspect, the present application provides a device for inhibiting bottom water coning by in-situ oxidation of crude oil, and a method for inhibiting bottom water coning by in-situ oxidation of crude oil, comprising:

[0015] A combined injection-production well pattern, comprising production horizontal wells and gas injection wells, wherein the production horizontal wells are arranged at the bottom of the oil layer in the bottom water development zone and the bottom water cone zone, and the gas injection wells are arranged between adjacent production horizontal wells, and the gas injection wells include gas injection horizontal wells and / or gas injection vertical wells;

[0016] A preheating unit is connected to the production horizontal well and the gas injection vertical well, and is used to preheat the oil layer in the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature through the production horizontal well and the gas injection vertical well to obtain a preheated oil layer;

[0017] The medium injection unit is connected to the gas injection horizontal well or the gas injection vertical well, and is used to inject an oxidizing medium into the preheated oil layer through the gas injection well, so that the oxidizing medium reacts with the crude oil in the preset oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer.

[0018] In some embodiments, the oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to obtain a mixture of colloidal heavy oil, coke, asphaltene sediments and associated gas, and the heavy oil, coke and asphaltene sediments form the isolation layer.

[0019] In some embodiments, the combined injection-production well network also includes a production vertical well, the gas injection well is a gas injection vertical well, and at least one production horizontal well is provided. The gas injection vertical well and the production vertical well are respectively provided on both sides of the production horizontal well. The gas injection vertical well is used to inject the oxidizing medium into the preheating oil layer, and the production vertical well is used to produce the associated gas generated by the oxidation reaction.

[0020] In some embodiments, the gas injection well is a horizontal gas injection well, and production horizontal wells are respectively arranged on both sides of the horizontal gas injection well. The horizontal gas injection well is used to inject the oxidizing medium into the preheating oil layer, and the production horizontal well is used to produce the associated gas generated by the oxidation reaction.

[0021] In some embodiments, the combined injection-production well network further includes auxiliary production vertical wells, which are arranged on both sides of the gas injection horizontal well or the production horizontal well to assist in producing the associated gas generated by the oxidation reaction.

[0022] In some embodiments, when the gas production of the production horizontal well is less than a preset threshold, the gas injection well adjacent to the production horizontal well is used as a production well.

[0023] The method for inhibiting bottom water coning by in-situ oxidation of crude oil provided in one or more embodiments of the present application has the following beneficial effects compared with the prior art:

[0024] Preheating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature to obtain a preheated oil layer; An oxidizing medium is continuously injected into the preheated oil layer so that the oxidizing medium undergoes an oxidation reaction with the crude oil in the preheated oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer, thereby enhancing the sealing capacity of the oil layer, reducing the thickness of the water-avoiding oil layer, effectively increasing the available reserves, and being able to suppress bottom water coning for a long time, thereby improving the effect of reservoir development. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic flow chart of a method for inhibiting bottom water coning by in-situ oxidation of crude oil in an embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram of water avoidance in a bottom water reservoir when no oxidizing medium is injected in an embodiment of the present invention is shown;

[0027] Figure 3 A schematic diagram showing water avoidance in a bottom water reservoir after injection of an oxidizing medium for oxidation according to an embodiment of the present invention is shown;

[0028] Figure 4 A comparison diagram of the vertical well perforation bottom boundary and horizontal well position in the conventional method and oxidation in an embodiment of the present invention is shown;

[0029] Figure 5 The graph shows the viscosity comparison of crude oil after original, dynamic and static oxidation in the embodiment of the present invention;

[0030] Figure 6 A schematic structural diagram of a plan view of a first combined injection-production well pattern in an embodiment of the present invention is shown;

[0031] Figure 7 A schematic structural diagram of a stereogram of a first combined injection-production well pattern in an embodiment of the present invention is shown;

[0032] Figure 8 A schematic structural diagram of a plan view of a second combined injection-production well pattern in an embodiment of the present invention is shown;

[0033] Fig. 9 A schematic structural diagram of a stereogram of a second combined injection-production well pattern in an embodiment of the present invention is shown;

[0034] Fig.10 It shows a schematic structural diagram of a plan view of a third combined injection-production well pattern in an embodiment of the present invention;

[0035] Fig.11 A schematic structural diagram of a stereogram of a third combined injection-production well pattern in an embodiment of the present invention is shown;

[0036] Fig.12 A schematic diagram of the structure of a target heating zone and a non-target heating zone in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0037] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0038] Before introducing the embodiments, extra-heavy oil and its oxidation reaction are explained. Crude oil with a viscosity of more than 50 millipascals is considered heavy oil, crude oil with a viscosity of more than 10,000 millipascals is called extra-heavy oil, and crude oil with a viscosity of more than 50,000 millipascals is called extra-heavy oil. The original temperature of the extra-heavy oil reservoir is low (generally below 50°C), the viscosity of the crude oil is high, and there is basically no flow ability under oil layer conditions. The properties of heavy oil are relatively stable, and oxidation and other reactions are difficult to occur under reservoir conditions. Indoor experimental studies have shown that when extra-heavy oil is oxidized at 90°C to 170°C, the viscosity of the crude oil increases linearly, and the increase rate gradually increases; group component analysis shows that the asphaltene and non-hydrocarbon content increases, and even non-hydrocarbon deposition occurs; such as Figure 5 As shown, the dynamic oxidation viscosity-increasing effect is significantly better than the static oxidation effect under the same conditions, and the viscosity after the reaction cannot even be measured; the indoor fluidity experiment of the colloid-like heavy oil formed by dynamic oxidation shows that it cannot melt at 100°C, can soften at 145°C, melt at 180°C, and can flow at 200°C.

[0039] In a first aspect of the embodiments of the present application, a method for inhibiting bottom water coning by in-situ oxidation of crude oil is provided. Figure 1-Figure 12 ,include:

[0040] Step S1: preheating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature to obtain a preheated oil layer;

[0041] Step S2: continuously injecting an oxidizing medium into the preheated oil layer, so that the oxidizing medium reacts with the crude oil in the preheated oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer.

[0042] In step S2, the changes in reservoir pressure and temperature can be analyzed and determined based on the temperature and pressure measurement data, and the reservoir reaction can be analyzed based on the associated gas production and components; based on the above data, 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, the process of injecting the medium is completed.

[0043] In this embodiment, the oxidizing medium can be air (hot air), oxygen-enriched air, oxygen-reduced air and other media that can effectively oxidize super-heavy oil. The preset oxidation temperature is 100-150°C, achieving a good oxidation temperature condition, and the oil layer about 3-5m above the bottom water zone is basically in the original state. Under the condition of the preset oxidation temperature, the oxidizing medium is injected, and the oxidizing medium reacts with the crude oil of the preheated oil layer to obtain a mixture of colloid-like heavy oil, coke and asphaltene sediments, and the mixture forms a sealing layer above the interface between the bottom water zone and the oil layer. The sealing layer includes a non-flowing colloid-like heavy oil and a coke deposition zone, which blocks the reservoir pores, thereby inhibiting the coning of the bottom water.

[0044] The method for inhibiting bottom water coning by in-situ oxidation of crude oil proposed in an embodiment of the present invention is to preheat the oil layer at the bottom of the bottom water development zone and the bottom water coning zone to a preset oxidation temperature to obtain a preheated oil layer; continuously inject an oxidizing medium into the preheated oil layer to cause an oxidation reaction between the oxidizing medium and the crude oil in the preheated oil layer to form an isolation layer above the interface between the bottom water zone and the oil layer, thereby enhancing the isolation capacity of the oil layer, reducing the thickness of the water-avoiding oil layer, effectively increasing the available reserves, and being able to inhibit bottom water coning for a long time, thereby improving the effect of reservoir development.

[0045] In some embodiments, the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone is preheated to a preset oxidation temperature, including: injecting steam or electric heating into the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to heat its temperature to a preset oxidation temperature.

[0046] In some implementations, steam injection is used for preheating, and the required steam volume and the time required for steam injection are calculated as follows:

[0047] First, calculate the total heat required to heat the injection-production well from the current oil layer temperature to the target oil layer temperature; then calculate the heat loss in the wellbore. For thermal production vertical wells and horizontal wells, the vertical well section generally uses insulated oil pipes + nitrogen insulation, etc., and the heat loss in the wellbore can be ignored. In contrast, the horizontal well section needs 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 steam and the formation, and convert the total heat required by the formation into steam injection. The details are as follows:

[0048] ① Calorie calculation:

[0049] Q1=π(R 2 -r 2 )h(1-φ)ρC(t1-t0) (1)

[0050] Q2=π(R 2 -r 2 )hφS O ρ O C O ρC(t1-t0) (2)

[0051] Q3=π(R 2 -r 2 )hφS w ρ w C w ρC(t1-t0) (3)

[0052] ∑Q=Q1+Q2+Q3 (4)

[0053]

[0054] Where: ∑Q is the total heating amount, kJ; Q1 is the heat of heating the rock to the preheating temperature within the preheating range, kJ; Q2 is the heat of heating the crude oil to the preheating temperature within the preheating range, kJ; Q3 is the heat of heating the water to the preheating temperature within the preheating range, 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; t1 is the preheating temperature, °C; t0 is the current oil layer temperature, °C; C is the specific heat of the rock, J / (g.°C); C O is the specific heat of crude oil, J / (g.℃); C w is the specific heat of water, J / (g.℃), C w =4.19J / (g.℃),γ O is the relative density of crude oil.

[0055] ② Heat loss Q when steam circulates in the horizontal well section L :

[0056] 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 is injected through the toe (point B) of the horizontal well and returns to the heel (point A), and the dryness is 0.

[0057] 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.

[0058] Secondly, use formulas (6) to (10) to calculate the steam enthalpy at the inlet and outlet of the horizontal section.

[0059] H w =4.095T+8.765×10 -4 T 2 T<240℃ (6)

[0060] H w =302+1.3T+7.315×10 -3 T 2 T≥240℃ (7)

[0061] L V =273×(374.15-T) 0.38 (8)

[0062] H s =X×L V +H w (9)

[0063]

[0064] In the formula, 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, °C; H s is the steam enthalpy, J / g; X is the steam quality, decimal; p s is the saturation pressure, MPa.

[0065] 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, which is also the heat loss Q when the steam circulates in the horizontal well section. L .

[0066] ③ Heat loss Q of oil layer in non-target heating zone ne

[0067] like Fig.12 As shown, the target heating area of ​​the horizontal section is R e , 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:

[0068]

[0069] By integrating the above formula, we can get:

[0070] Then we have:

[0071] 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).

[0072] In the formula, i s is the steam injection rate, kg / h; h m is the enthalpy of saturated water vapor, kJ / Kg; Mr is the heat capacity of the oil layer, kJ / (m 3 .℃); T R is the original oil layer temperature, °C; T s is the injection steam temperature, °C; T e Set a target temperature for the target heating zone.

[0073] ④The heat required to heat the oil layer in the target heating zone Q e

[0074] 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 .

[0075] ⑤Calculate steam injection volume and injection time

[0076] Total amount of steam to be injected: Q 总 =Q L +Q e +Q ne (14)

[0077] Based on the heat required for the above calculation and the thermal properties of steam, calculate the amount of steam injected: q inj =Q 总 / Q 蒸 (15)

[0078] In formula (15), q inj is the amount of steam injected, m 3 ;Q 总 is the total amount of steam to be injected, kJ; Q 蒸 is the heat per unit volume of steam under the same temperature, pressure and dryness conditions, kJ / m 3 .

[0079] Steam injection time:

[0080] t inj =q inj / v inj (16)

[0081] In formula (16), t inj is the gas injection time, h; q inj is the amount of steam injected, m 3 ; ν inj is the steam injection rate, m 3 / h.

[0082] The heating time required for preheating by electric heating is calculated as follows:

[0083] Calculate the total heat required Q according to the above formulas (1) to (14): 总 ;

[0084] Then calculate the heating time: t ele =Q 总 / P (17)

[0085] In the formula, t ele is the heating time of electric heating, h; P is the output power of the heating cable, kJ / h.

[0086] In some embodiments, the method further includes injecting a catalyst, an oxidant and other composite additives through a gas injection vertical well or a gas injection horizontal well to promote an oxidation reaction between the medium and the extra-heavy oil.

[0087] In some embodiments, the preset oxidation temperature is 100-150°C. When the oil layer temperature does not meet the preset oxidation temperature requirement, water injection cooling, steam heating, nitrogen injection insulation and adjustment of injection medium parameters can be used to adjust the oil layer temperature. Through the above means, the oxidation reaction is ensured to be carried out continuously and effectively, and reliability and stability are ensured.

[0088] In some embodiments, after the oil layer is preheated to a preset oxidation temperature through a production horizontal well, the process further includes: setting the well-to-well connection temperature to be greater than 100°C and setting the injection-production ratio to be greater than 1.0. By setting the above parameters, the oxidation reaction can be continued, ensuring the formation isolation capacity and continuously suppressing the coning of bottom water.

[0089] In a specific embodiment, in a bottom-water super-heavy oil reservoir, there is no continuous pure mudstone barrier between the bottom water bodies of the oil layer, the bottom boundary of the production vertical well perforation is more than 20m away from the oil-water interface, and the horizontal well avoids the bottom water thickness of about 15m; the overall vertical well + horizontal well combination steam huff and puff development is adopted. At present, the average huff and puff cycle is 15.8 cycles, the formation pressure in the main part has dropped to less than 2MPa, and some well areas have been shut down and intermittent due to bottom water coning. In order to control the risk of bottom water coning, a combination of vertical well + horizontal well and horizontal well + horizontal well injection and production is adopted in the bottom water area. The horizontal well is deployed at the bottom of the oil layer, 5-7m away from the oil-water interface. The bottom boundary of the vertical well perforation is slightly higher than the horizontal section, and the perforation position is 1 / 4-1 / 2 of the corresponding layer section of the horizontal well. First, the horizontal well uses steam circulation or electric heating to preheat the oil layer. The preheating radius is 3-5m, so that the oil layer temperature is 100℃-150℃, that is, it reaches a good oxidation temperature condition and the oil layer near the top of the bottom water 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 it is heated from the initial temperature to above 100℃, the heat required to be injected is 6.5×10 9 kJ, if the circulation preheating is adopted, when the steam injection rate is 90t / d and the wellhead dryness is 95%, it takes about 8 months to preheat. If the whole well section is electrically heated, it takes 7-8 months. Then, the injection well is injected 1-2m above the horizontal section with 2×10 4 ~5×10 4 m3 Air is continuously injected at a gas injection rate of / d, and the oxygen in the injected air undergoes an oxidation reaction with the formation crude oil. The production wells and auxiliary production wells produce associated gas, and the production-injection ratio is about 1.0. In order to ensure the degree of oxidation reaction between the injection and production wells, when the gas production of the production horizontal wells is greatly reduced, the injection and production wells of the adjacent wells can be exchanged to make the crude oil reaction between the wells more complete. Ultimately, a high-viscosity heavy oil and coke deposition zone with a thickness of about 10m is formed above the oil-water interface, which increases the formation isolation capacity, reduces the water-avoiding oil layer to about 10m, increases the available reserves, and at the same time inhibits the coning of bottom water to improve the production effect of the reservoir.

[0090] In a second aspect of an embodiment of the present application, a device for inhibiting bottom water coning by in-situ oxidation of crude oil is provided, and the method for inhibiting bottom water coning by in-situ oxidation of crude oil according to the first aspect is used, comprising:

[0091] A combined injection-production well pattern includes production horizontal wells and gas injection wells. The production horizontal wells are arranged at the bottom of the oil layer in the bottom water development zone and the bottom water cone zone. The gas injection wells are arranged between adjacent production horizontal wells. The gas injection wells include gas injection horizontal wells and / or gas injection vertical wells.

[0092] A preheating unit is connected to the production horizontal well and the gas injection vertical well, and is used to preheat the oil layer in the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature through the production horizontal well and the gas injection vertical well to obtain a preheated oil layer;

[0093] The medium injection unit is connected to the gas injection horizontal well or the gas injection vertical well, and is used to inject an oxidizing medium into the preheated oil layer through the gas injection well, so that the oxidizing medium reacts with the crude oil in the preset oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer.

[0094] In some embodiments, the oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to obtain a mixture of colloid-like heavy oil, coke, asphaltene sediments and associated gas heavy oil, coke and asphaltene sediments to form an isolation layer. The isolation layer includes a non-flowing colloid-like heavy oil and coke deposition zone, which blocks the reservoir pores, thereby inhibiting the coning of bottom water.

[0095] In some embodiments, the combined injection-production well network also includes a production vertical well, the gas injection well is a gas injection vertical well, and at least one production horizontal well is provided. A gas injection vertical well and a production vertical well are respectively provided on both sides of the production horizontal well. The gas injection vertical well is used to inject oxidizing medium into the preheated oil layer, and the production vertical well is used to produce associated gas generated by the oxidation reaction.

[0096] In some embodiments, the gas injection well is a horizontal gas injection well, and production horizontal wells are respectively arranged on both sides of the horizontal gas injection well. The horizontal gas injection well is used to inject oxidizing medium into the preheated oil layer, and the production horizontal well is used to produce associated gas generated by the oxidation reaction.

[0097] In some embodiments, the combined injection-production well network further includes auxiliary production vertical wells, which are arranged on both sides of the gas injection horizontal well or the production horizontal well to assist in producing associated gas generated by the oxidation reaction.

[0098] For the above three types of combined injection and production well patterns, the injection and production well spacing needs to be determined comprehensively according to the crude oil properties of different oil reservoirs and their preheating range and other conditions, but it is best to form thermal connectivity between the injection and production wells. In order to achieve better isolation effect and release more water-avoiding thickness, it is recommended that the heating wells be deployed about 5-7m above the bottom water. It is predicted that a high-viscosity colloid heavy oil and coke deposition zone of about 10m will be formed, releasing a water-avoiding oil layer thickness of about 10m; at the same time, the high-viscosity colloid heavy oil and coke deposition zone formed can effectively inhibit the intrusion of the bottom of the cone area and improve the development effect; considering the gas overlay effect and later regulation, it is recommended that the vertical well perforate the lower 1 / 4-1 / 2 of the corresponding layer; in order to continuously cause oxidation reaction, it is recommended that the inter-well connection temperature after preheating be >100℃, and the production-injection ratio be about 1.0.

[0099] In some embodiments, when the gas production of the production horizontal well is less than a preset threshold, the gas injection well adjacent to the production horizontal well is used as a production well. When the gas production of the production horizontal well 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 the adjacent wells to make the crude oil in the oxidation reaction zone react more fully. The main purpose is to ensure that the horizontal well section and its upper oil layer continue to be dynamically oxidized, and finally form a high-viscosity colloid-like heavy oil and coke deposition zone with basically no flow ability above the bottom water zone, increase the formation isolation capacity, which is equivalent to increasing the thickness of the "interlayer", releasing the original part of the water-avoiding thickness, and increasing the movable reserves; and further reduce the risk of bottom water coning.

[0100] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0101] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0102] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0103] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0104] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for inhibiting bottom water coning by in-situ oxidation of crude oil, characterized in that: include: Preheating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature to obtain a preheated oil layer; An oxidizing medium is continuously injected into the preheated oil layer, so that the oxidizing medium undergoes an oxidation reaction with the crude oil in the preheated oil layer, so as to form a sealing layer above the interface between the bottom water zone and the oil layer.

2. The method for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 1, characterized in that: The method of preheating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature includes: injecting steam or electrically heating the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone to heat the oil layer to the preset oxidation temperature.

3. The method for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 2, characterized in that: Calculate the total heat required to heat its temperature to the preset oxidation temperature: Q 总 =Q L +Q e +Q ne , where Q L is the heat loss of steam when it circulates in the well, kJ, Q e The heat required to heat the oil layer at the bottom of the bottom water development zone and the bottom water cone entry zone, Q ne The heat required to heat the oil layer other than the preheated oil layer; the time required to heat to the preset oxidation temperature t = Q is obtained by the total heat and the heating rate 总 / P, where t is time, h, and P are heating rates.

4. The method for inhibiting bottom water coning by in-situ oxidation of crude oil according to any one of claims 1 to 3, characterized in that: The preset oxidation temperature is 100-150°C.

5. The method for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 1, characterized in that: The oxidizing medium is air, hot air, oxygen-enriched air, oxygen-reduced air and other media that react with crude oil for oxidation.

6. The method for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 5, characterized in that: The oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer, including: the oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to obtain a mixture of colloid-like heavy oil, coke and asphaltene sediments, and the mixture forms a sealing layer above the interface between the bottom water zone and the oil layer.

7. The method for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 1, characterized in that: The method of continuously injecting an oxidizing medium into the preheated oil layer to cause an oxidation reaction between the oxidizing medium and the crude oil in the preheated oil layer includes injecting a catalyst, an oxidant and a composite auxiliary agent while injecting the oxidizing medium to promote the oxidation reaction.

8. A device for inhibiting bottom water coning by in-situ oxidation of crude oil, using the method for inhibiting bottom water coning by in-situ oxidation of crude oil as claimed in any one of claims 1 to 7, characterized in that: include: A combined injection-production well pattern, comprising production horizontal wells and gas injection wells, wherein the production horizontal wells are arranged at the bottom of the oil layer in the bottom water development zone and the bottom water cone zone, and the gas injection wells are arranged between adjacent production horizontal wells, and the gas injection wells include gas injection horizontal wells and / or gas injection vertical wells; A preheating unit is connected to the production horizontal well and the gas injection vertical well, and is used to preheat the oil layer in the bottom water development zone and the bottom water cone entry zone to a preset oxidation temperature through the production horizontal well and the gas injection vertical well to obtain a preheated oil layer; The medium injection unit is connected to the gas injection horizontal well or the gas injection vertical well, and is used to inject an oxidizing medium into the preheated oil layer through the gas injection well, so that the oxidizing medium reacts with the crude oil in the preset oil layer to form a sealing layer above the interface between the bottom water zone and the oil layer.

9. The device for inhibiting bottom water coning by in-situ oxidation of crude oil as claimed in claim 10, characterized in that: The oxidizing medium undergoes an oxidation reaction with the crude oil of the preheated oil layer to obtain a mixture of colloid-like heavy oil, coke, asphaltene sediment and associated gas, and the heavy oil, coke and asphaltene sediment forms the isolation layer.

10. The device for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 9, characterized in that: The combined injection-production well network also includes a production vertical well, the gas injection well is a gas injection vertical well, and at least one production horizontal well is provided. The gas injection vertical well and the production vertical well are respectively provided on both sides of the production horizontal well. The gas injection vertical well is used to inject the oxidizing medium into the preheating oil layer, and the production vertical well is used to produce the associated gas generated by the oxidation reaction.

11. The device for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 9, characterized in that: The gas injection well is a horizontal gas injection well, and production horizontal wells are respectively arranged on both sides of the horizontal gas injection well. The horizontal gas injection well is used to inject the oxidizing medium into the preheating oil layer, and the production horizontal well is used to produce the associated gas generated by the oxidation reaction.

12. The device for inhibiting bottom water coning by in-situ oxidation of crude oil according to claim 11, characterized in that: The combined injection-production well network also includes auxiliary production vertical wells, which are arranged on both sides of the gas injection horizontal well or the production horizontal well to assist in producing the associated gas generated by the oxidation reaction.

13. The device for inhibiting bottom water coning by in-situ oxidation of crude oil according to any one of claims 8 to 12, characterized in that: When the gas production of the production horizontal well is less than a preset threshold, the gas injection well adjacent to the production horizontal well is used as a production well.

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