Method and device for inhibiting edge water invasion through in-situ oxidation of crude oil

Abstract

The invention discloses a method and device for restraining edge water invasion through crude oil in-situ oxidation, and the method comprises the steps that a combined injection and production well network composed of production wells and gas injection wells is arranged in the area, close to an edge water area, in an oil layer of an edge water development area; the oil layer is preheated to a preset oxidation temperature through the production well and the gas injection well; an oxidizing medium is continuously injected into the oil layer through the gas injection well, so that the oxidizing medium and crude oil of the oil layer of the edge water development area are subjected to oxidation reaction, non-flowability colloidal thick oil and coke deposition zones are formed on the inner side of the interface of the oil layer and the edge water area, the oil layer packing capacity is enhanced, the thickness of the water-avoiding oil layer is reduced, and the movable reserve is effectively increased; nitrogen is injected into the oil layer of the edge water development area with the pressure drop exceeding the preset threshold value or presenting the edge water invasion trend through the gas injection well, so that the formation pressure is supplemented, edge water invasion is restrained, the oxidation reaction is aggravated along with pressure rise, and the coke generation amount is increased, and the oil layer plugging capacity is further enhanced.

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 edge water intrusion 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 edge water invasion. Once the edge water invades, the production wells near the invaded wells need to be shut down, affecting the effect of reservoir development.

[0003] In the existing heavy oil reservoir development process, a certain distance is generally reserved at the boundary between the oil layer in the production area and the edge water area as a "barrier" or "buffer zone" to slow down the invasion of edge water. However, the available reserves of the reservoir are sacrificed. Moreover, as the reservoir is gradually developed, the formation pressure gradually decreases, and the problem of edge water invasion becomes more serious. Summary of the invention

[0004] In order to solve the technical problems that a certain distance is reserved at the boundary between the oil layer and the edge water zone in the current mining area to delay the invasion of edge water, which sacrifices the available reserves of the oil reservoir, and the formation pressure gradually decreases with the gradual development of the oil reservoir, making the edge water invasion problem more serious, the present application provides a method and device for inhibiting the invasion of edge water by in-situ oxidation of crude oil.

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

[0006] A combined injection-production well network consisting of production wells and gas injection wells is set in an area close to the edge water area in the oil layer of the edge water development area;

[0007] Preheating the oil layer to a preset oxidation temperature through production wells and gas injection wells;

[0008] Inject nitrogen through gas injection wells into oil layers in edge water development areas where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure;

[0009] The oxidizing medium is continuously injected into the oil layer through the gas injection well, so that the oxidizing medium reacts with the crude oil in the oil layer of the edge water development area to form a non-flowable colloid-like heavy oil and coke deposition zone inside the interface between the oil layer and the edge water area.

[0010] In some embodiments, the volume of the injected nitrogen is determined according to the boost value, according to the formula The volume of injected nitrogen V2 is calculated, where P1 is the current reservoir pressure, MPa; T1 is the current reservoir temperature, K; V1 is the volume of nitrogen injected at the current temperature and pressure, m 3 ; ΔP is the difference between the target reservoir pressure and the current reservoir pressure, MPa; V2 is the volume of nitrogen injected at the target temperature and pressure, m 3 ; T2 is the target oil layer temperature, K.

[0011] In some embodiments, the combined injection-production well network includes gas injection vertical wells and production vertical wells, and the gas injection vertical wells and production vertical wells are cross-arranged in the oil layer of the edge water development zone near the edge water zone; nitrogen and the oxidizing medium are injected through the gas injection vertical wells, and the associated gas produced by the oxidation reaction is produced by the production vertical wells.

[0012] In some embodiments, the combined injection-production well network includes production horizontal wells and gas injection horizontal wells, and the gas injection horizontal wells are arranged below the production horizontal wells; nitrogen and the oxidizing medium are injected through the gas injection horizontal wells, and the associated gas generated by the oxidation reaction is produced by the production horizontal wells.

[0013] In some embodiments, the combined injection-production well network further includes vertical production wells, which are disposed 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.

[0014] In some embodiments, when the gas production of the vertical production well or the horizontal production well is less than a preset threshold, a well adjacent to the vertical production well or the horizontal production well is replaced with a production well.

[0015] In some embodiments, preheating the oil layer through production wells and gas injection wells includes: injecting steam through production horizontal wells to preheat the oil layer by steam huff and puff or circulation preheating; or preheating the oil layer by electric heating.

[0016] In some embodiments, the time required to heat to the preset oxidation temperature t=Q is obtained based on the total heat required for preheating to the preset oxidation temperature and the heating rate. 总 / P, where t is time, h, P is heating rate, Q 总 The total amount of heat required for preheating to the preset oxidation temperature; the total amount of heat required for preheating 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 eThe 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 oil layers other than the preheated oil layer.

[0017] In some embodiments, the process further includes injecting catalysts, oxidants and other composite additives into the oil layer in the edge water development zone through a gas injection well to promote oxidation reaction between the oxidizing medium and the crude oil in the oil layer in the edge water development zone.

[0018] In some embodiments, the preset oxidation temperature is 100-150°C. When the oil layer temperature does not meet the requirements of the preset oxidation temperature, water injection for cooling, steam heating, nitrogen injection for insulation and adjustment of injection medium parameters can be used to adjust the oil layer temperature.

[0019] In some embodiments, after the oil layer is preheated to a preset oxidation temperature through production wells and gas injection wells, the process further includes: making the inter-well connection temperature greater than 100° C. and setting the injection-production ratio to greater than 1.0.

[0020] In a second aspect, the present application provides a device for inhibiting edge water intrusion by in-situ oxidation of crude oil, and a method for inhibiting edge water intrusion by in-situ oxidation of crude oil, comprising:

[0021] A combined injection-production well pattern, comprising production wells and gas injection wells, wherein the production wells and the gas injection wells are arranged in an area close to an edge water zone in an oil layer in an edge water development zone;

[0022] A preheating unit, connected to the production well and the gas injection well, for preheating the oil layer to a preset oxidation temperature through the production well and the gas injection well;

[0023] A nitrogen injection unit connected to the gas injection well is used to inject nitrogen into the oil layer in the edge water development zone where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure;

[0024] The medium injection unit is connected to the gas injection well and is used to inject an oxidizing medium into the oil layer so that the oxidizing medium reacts with the crude oil in the oil layer of the edge water development zone to form a non-flowable colloid-like heavy oil and coke deposition zone inside the interface between the oil layer and the edge water zone.

[0025] In some embodiments, the combined injection-production well network includes gas injection vertical wells and production vertical wells, and the gas injection vertical wells and production vertical wells are cross-arranged in the oil layer of the edge water development zone near the edge water zone. The gas injection vertical wells are used to inject nitrogen and the oxidizing medium into the oil layer, and the production vertical wells are used to produce the associated gas generated by the oxidation reaction.

[0026] In some embodiments, the combined injection-production well network includes production horizontal wells and gas injection horizontal wells, wherein the gas injection horizontal wells are arranged below the production horizontal wells, the gas injection horizontal wells are used to inject nitrogen and the oxidizing medium into the oil layer, and the production horizontal wells are used to produce the associated gas generated by the oxidation reaction.

[0027] The method for inhibiting edge water intrusion 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:

[0028] By continuously injecting an oxidizing medium into the oil layer through the gas injection well, an oxidation reaction occurs between the oxidizing medium and the crude oil in the oil layer in the edge water development zone, so as to form a non-flowing colloidal heavy oil and coke deposition zone on the inner side of the interface between the oil layer and the edge water zone, thereby enhancing the oil layer sealing capacity, reducing the thickness of the water-avoiding oil layer, and effectively increasing the available reserves; by injecting nitrogen through the gas injection well into the oil layer in the edge water development zone where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure and thereby inhibit the edge water invasion; at the same time, as the pressure increases, the oxidation reaction intensifies, thereby increasing the amount of coke generated and further enhancing the oil layer sealing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic flow chart of a method for inhibiting edge water intrusion by in-situ oxidation of crude oil in an embodiment of the present invention is shown;

[0030] Figure 2 A schematic diagram showing a comparison of water avoidance conditions of edge water reservoirs before and after oxidation in an embodiment of the present invention is shown;

[0031] Figure 3 The schematic diagram showing the comparison of crude oil viscosity after original, dynamic and static oxidation in an embodiment of the present invention is shown;

[0032] Figure 4 The plane diagram of the first combined injection-production well pattern in the embodiment of the present invention is shown. Figure 1 Schematic diagram of the structure;

[0033] Figure 5 The plane diagram of the first combined injection-production well pattern in the embodiment of the present invention is shown. Figure 2 Schematic diagram of the structure;

[0034] Figure 6 A schematic structural diagram of a stereogram of a first combined injection-production well pattern in an embodiment of the present invention is shown;

[0035] Figure 7 A schematic structural diagram of a stereogram of a second combined injection-production well pattern in an embodiment of the present invention is shown;

[0036] Figure 8A schematic structural diagram of a stereogram of a third combined injection-production well pattern in an embodiment of the present invention is shown;

[0037] Fig. 9 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

[0038] 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.

[0039] 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 3 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.

[0040] See also Figure 1-Figure 9 The embodiment of the present invention provides a method for inhibiting edge water intrusion by in-situ oxidation of crude oil, comprising:

[0041] Step S1: a combined injection-production well network consisting of production wells and gas injection wells is set in the area close to the edge water area in the oil layer of the edge water development area; in order to achieve a better plugging and reserve increase effect, it is recommended to deploy the injection-production well network at a well spacing from the edge water area, and it is expected to form a high-viscosity colloid heavy oil zone of half a well spacing to 1 well spacing, and the reserves within the water avoidance distance of about 1 well spacing can be released on the plane.

[0042] Step S2: preheating the oil layer to a preset oxidation temperature through the production well and the gas injection well;

[0043] Step S3: injecting nitrogen through a gas injection well into an oil layer in an edge water development zone where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure;

[0044] Step S4: continuously injecting oxidizing medium into the oil layer through the gas injection well, so that the oxidizing medium reacts with the crude oil in the oil layer of the edge water development area to form a non-flowable colloid-like heavy oil and coke deposition zone inside the interface between the oil layer and the edge water area.

[0045] In this embodiment, nitrogen has a small thermal conductivity and is a heat-insulating material, which can play a good role in heat insulation. At the same time, the density of nitrogen is lower than that of steam and carbon dioxide, and can be distributed in the upper part of the oil layer. Nitrogen has a higher expansibility than other gases, but its solubility in crude oil is very low, so the main mechanism of N2 is low thermal conductivity effect and pressurization. The oxidizing medium can be air (hot air), oxygen-enriched air, oxygen-reduced air, and other oxidizing media that can effectively oxidize the crude oil in the oil layer of the edge water development area. The preset oxidation temperature is 100-150°C to achieve a better oxidation temperature condition.

[0046] The method for suppressing edge water intrusion by in-situ oxidation of crude oil proposed in an embodiment of the present invention comprises: continuously injecting an oxidizing medium into the oil layer through a gas injection well, causing an oxidation reaction between the oxidizing medium and the crude oil in the oil layer in the edge water development zone to form a non-flowing colloidal heavy oil and coke deposition zone on the inner side of the interface between the oil layer and the edge water zone, thereby enhancing the oil layer sealing capacity, reducing the thickness of the water-avoiding oil layer, and effectively increasing the available reserves; injecting nitrogen through the gas injection well into the oil layer in the edge water development zone where the pressure drop exceeds a preset threshold or has shown an edge water intrusion trend to supplement the formation pressure, thereby suppressing edge water intrusion; at the same time, as the pressure increases, the oxidation reaction intensifies, which can increase the amount of coke generated and further enhance the oil layer sealing capacity.

[0047] In some embodiments, the volume of the injected nitrogen is determined according to the boost value. Specifically, The volume of injected nitrogen V2 is calculated as follows: In formula (1), P1 is the current reservoir pressure, MPa; T1 is the current reservoir temperature, K; V1 is the volume of nitrogen injected at the current temperature and pressure, m 3 ; ΔP is the difference between the target reservoir pressure and the current reservoir pressure, MPa; V2 is the volume of nitrogen injected at the target temperature and pressure, m 3 ; T2 is the target oil layer temperature, K. The volume of injected nitrogen is determined by reservoir numerical simulation and reservoir engineering calculation. During the injection process, it should be adjusted according to the temperature and pressure monitoring data. The above reservoir numerical simulation and reservoir engineering calculation adopt the existing technology and will not be repeated here.

[0048] In a specific embodiment, the combined injection-production well pattern includes gas injection vertical wells and production vertical wells, and the gas injection vertical wells and production vertical wells are cross-arranged in the oil layer of the edge water development zone near the edge water zone; nitrogen and the oxidizing medium are injected through the gas injection vertical wells, and the associated gas produced by the oxidation reaction is produced by the production vertical wells. Figure 4 and Figure 5 As shown, the gas injection vertical wells and production vertical wells can be arranged opposite to each other or staggered. First, the gas injection vertical wells and production vertical wells use steam huff and puff, steam circulation or electric heating to preheat the oil layer, so that the oil layer temperature reaches the preset oxidation temperature and pressure conditions, and thermal connection is formed between the injection and production wells; secondly, the gas injection vertical wells inject injection air or other media, and the adjacent production vertical wells control liquid production, mainly producing associated gas. At the same time, according to the actual injection and production situation, the gas injection vertical wells and production vertical wells can be rotated in time.

[0049] In another specific embodiment, the combined injection-production well network includes production horizontal wells and gas injection horizontal wells, and the gas injection horizontal wells are arranged below the production horizontal wells; nitrogen and the oxidizing medium are injected through the gas injection horizontal wells, and the associated gas generated by the oxidation reaction is produced by the production horizontal wells. First, the production horizontal wells and the gas injection horizontal wells use steam huff-and-puff, steam circulation or electric heating to preheat the oil layer, so that the oil layer temperature reaches the preset oxidation temperature and pressure conditions, and thermal connection is formed between the injection and production wells; secondly, the gas injection horizontal wells inject injection air or other media, and the adjacent production horizontal wells control liquid production, mainly producing associated gas. At the same time, according to the actual injection and production situation, the gas injection horizontal wells and the production horizontal wells can be rotated in time.

[0050] In a further embodiment, the combined injection-production well pattern further comprises vertical production 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. The vertical production wells are arranged to assist in producing the associated gas to ensure the injection-production ratio.

[0051] In the above three types of combined injection-production well patterns, the injection-production well spacing needs to be determined comprehensively based on the crude oil properties of different reservoirs and their preheating range. In order to continuously produce oxidation reactions, it is recommended that the inter-well connection temperature after preheating be >100°C and the production-injection ratio be above 1.0.

[0052] In some embodiments, when the gas production of the production vertical well or the production horizontal well is less than a preset threshold, the well adjacent to the production vertical well or the production horizontal well is replaced as a production well. When the gas production of the production vertical well or 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 oxidation reaction in the reaction zone more sufficient. The main purpose is to ensure that the oil layer in the target section continues to be dynamically oxidized, and finally form a high-viscosity colloid-like heavy oil zone with no flow ability, increase the deposition of coke and asphaltene in the pores, and increase the isolation capacity of the formation, which is equivalent to increasing the width of the "water avoidance zone", reducing the risk of edge water intrusion, while releasing the original part of the water avoidance zone volume, and increasing the available reserves.

[0053] In some embodiments, preheating the oil layer through production wells and gas injection wells includes: injecting steam through production horizontal wells to preheat the oil layer by steam huff and puff or circulation preheating; or preheating the oil layer by electric heating.

[0054] The injected steam is used to preheat the oil layer in a cyclic preheating manner. The required steam volume and the time required for steam injection are calculated as follows:

[0055] First, calculate the total heat required to heat the lowest temperature between the injection and production wells from the current oil layer temperature to the target oil layer target 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; 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 steam and the formation, and convert the total heat required by the formation into steam injection. The details are as follows:

[0056] ① Calorie calculation:

[0057] Q1=π(R 2 -r 2 )h(1-φ)ρC(t1-t0) (2)

[0058] Q2=π(R 2 -r 2 )hφS o ρ o C o ρC(t1-t0) (3)

[0059] Q3=π(R 2 -r 2 )hφS w ρ w C w ρ C (t1-t0) (4)

[0060] ∑Q=Q1+Q2+Q3 (5)

[0061]

[0062] 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.

[0063] ② Heat loss Q when steam circulates in the horizontal well section L :

[0064] 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.

[0065] 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.

[0066] Secondly, use formulas (7) to (11) to calculate the steam enthalpy at the inlet and outlet of the horizontal section.

[0067] H w =4.095T+8.765×10 -4 T 2 T<240℃ (7)

[0068] H w =302+1.3T+7.315×10 -3 T 2 T≥240℃ (8)

[0069] L V =273×(374.15-T) 0.38 (9)

[0070] H s =X×L V +H w (10)

[0071]

[0072] 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.

[0073] 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 .

[0074] ③ Heat loss Q of oil layer in non-target heating zone ne

[0075] like Fig. 9 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:

[0076]

[0077] By integrating the above formula, we can get:

[0078] Then we have:

[0079] 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 (2) to (6) and (13) to (14).

[0080] In the formula, i s is the steam 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 / (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.

[0081] ④The heat required to heat the oil layer in the target heating zone Q e

[0082] 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 .

[0083] ⑤Calculate steam injection volume and injection time

[0084] Total amount of steam to be injected: Q 总 =Q L +Q e +Q ne (15)

[0085] 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 (16)

[0086] In formula (16), q inj is the amount of steam injected, m 3 ; Qtotal 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 .

[0087] Steam injection time: t inj =q inj / v inj (17)

[0088] In formula (17), 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.

[0089] The heating time required for preheating by electric heating is calculated as follows:

[0090] Calculate the total heat required Q according to the above formulas (1) to (14): 总；

[0091] Then calculate the heating time: t ele =Q 总 / P (18)

[0092] Where, t ele is the heating time of electric heating, h; P is the output power of the heating cable, kJ / h.

[0093] In some embodiments, the method further includes injecting a catalyst, an oxidant and other composite additives into the oil layer in the edge water development zone through a gas injection well to promote an oxidation reaction between the oxidizing medium and the crude oil in the oil layer in the edge water development zone. Through the above means, the oxidation reaction can be ensured to be carried out continuously and effectively, and reliability and stability can be ensured.

[0094] 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 can be ensured to be carried out continuously and effectively, ensuring reliability and stability.

[0095] In some embodiments, after the oil layer is preheated to a preset oxidation temperature through the production well and the gas injection 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 oil layer isolation capacity and continuously suppressing edge water intrusion.

[0096] This embodiment is also applied to a certain medium-thick interbedded edge water reservoir, where the distance between the production well and the edge water is 200m-250m (about 2 well spacings), and steam huff and puff development is adopted. The average huff and puff is 11.3 cycles at present, the formation pressure is 1.64MPa, the pressure drop is large, and the risk of edge water invasion is high. In order to delay and suppress edge water invasion, the reservoir conditions and the existing well network are comprehensively considered, and the injection and production well network is deployed in an area about 100m away from the edge water area according to the actual situation of the oil-water interface.

[0097] First, nitrogen is injected into the gas injection well and the production well to increase the oil layer pressure to about 2MP. Then, the gas injection well and the production well are preheated by steam injection and exhalation. When the oil layer temperature reaches 120-150℃ and the injection and production wells are thermally connected, the gas injection wells are switched to air injection and the production wells are started for production. At the same time, the associated gas and temperature and pressure changes are monitored. When the temperature and chemical reaction rate decrease significantly, the gas injection well and the oil production well are steam-heated or electrically heated to increase the oxidation reaction rate. It is calculated that when the oil layer depth is about 600m, the distance between the injection and production wells is 20m-50m, and the oil layer thickness is 20m, when the target oil layer is heated from the initial temperature to above 100℃, 6.8×10 9 kJ, if a heating cable with an output power of 1MW is used, it will take 1 to 3 months to electrically heat the entire well section of the oil layer.

[0098] Then, 0.4×10 4 ~0.6×10 4 m 3Air is continuously injected at a gas injection rate of / d, and the oxygen in the injected air undergoes oxidation reaction with the formation crude oil. The generated associated gas is mainly produced through production wells, with a production-injection ratio of about 1.0. In order to ensure the degree of oxidation reaction between injection and production wells, when the gas production of the production 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. After several adjustments, the oil layer between the injection and production wells eventually forms a high-viscosity heavy oil and coke deposition zone with a width greater than 20m and a thickness basically the same as the oil layer, which increases the formation isolation capacity, inhibits the intrusion of edge water in the late stage of throughput, and at the same time turns the water-avoiding oil layer above 100m into a movable oil layer, increases the movable reserves, and effectively inhibits the intrusion of edge water.

[0099] Based on the same inventive concept, an embodiment of the present invention provides a device for inhibiting edge water intrusion by in-situ oxidation of crude oil, and the method for inhibiting edge water intrusion by in-situ oxidation of crude oil described above includes:

[0100] A combined injection-production well pattern, comprising production wells and gas injection wells, wherein the production wells and the gas injection wells are arranged in an area close to an edge water zone in an oil layer in an edge water development zone;

[0101] A preheating unit, connected to the production well and the gas injection well, for preheating the oil layer to a preset oxidation temperature through the production well and the gas injection well;

[0102] A nitrogen injection unit connected to the gas injection well is used to inject nitrogen into the oil layer in the edge water development zone where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure;

[0103] The medium injection unit is connected to the gas injection well and is used to inject an oxidizing medium into the oil layer so that the oxidizing medium reacts with the crude oil in the oil layer of the edge water development zone to form a non-flowable colloid-like heavy oil and coke deposition zone inside the interface between the oil layer and the edge water zone.

[0104] In some embodiments, the combined injection-production well network includes gas injection vertical wells and production vertical wells, and the gas injection vertical wells and production vertical wells are cross-arranged in the oil layer of the edge water development zone near the edge water zone. The gas injection vertical wells are used to inject nitrogen and the oxidizing medium into the oil layer, and the production vertical wells are used to produce the associated gas generated by the oxidation reaction.

[0105] In some embodiments, the combined injection-production well network includes production horizontal wells and gas injection horizontal wells, wherein the gas injection horizontal wells are arranged below the production horizontal wells, the gas injection horizontal wells are used to inject nitrogen and the oxidizing medium into the oil layer, and the production horizontal wells are used to produce the associated gas generated by the oxidation reaction.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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 edge water intrusion by in-situ oxidation of crude oil, characterized in that: include: A combined injection-production well network consisting of production wells and gas injection wells is set in an area close to the edge water area in the oil layer of the edge water development area; Preheating the oil layer to a preset oxidation temperature through production wells and gas injection wells; Inject nitrogen through gas injection wells into oil layers in edge water development areas where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure; The oxidizing medium is continuously injected into the oil layer through the gas injection well, so that the oxidizing medium reacts with the crude oil in the oil layer of the edge water development area to form a non-flowable colloid-like heavy oil and coke deposition zone inside the interface between the oil layer and the edge water area.

2. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: The volume of nitrogen injected is determined according to the boost value, according to the formula The volume of injected nitrogen V2 is calculated, where P1 is the current reservoir pressure, MPa; T1 is the current reservoir temperature, K; V1 is the volume of nitrogen injected at the current temperature and pressure, m 3 ; ΔP is the difference between the target reservoir pressure and the current reservoir pressure, MPa; V2 is the volume of nitrogen injected at the target temperature and pressure, m 3 ; T2 is the target oil layer temperature, K.

3. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: The combined injection-production well network includes gas injection vertical wells and production vertical wells, and the gas injection vertical wells and production vertical wells are cross-arranged in the oil layer of the edge water development zone near the edge water zone; nitrogen and the oxidizing medium are injected through the gas injection vertical wells, and the associated gas produced by the oxidation reaction is produced by the production vertical wells.

4. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: The combined injection-production well network includes production horizontal wells and gas injection horizontal wells, wherein the gas injection horizontal wells are arranged below the production horizontal wells; nitrogen and the oxidizing medium are injected through the gas injection horizontal wells, and the associated gas generated by the oxidation reaction is produced by the production horizontal wells.

5. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 4, characterized in that: The combined injection-production well network also includes vertical production 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.

6. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 3 or 4, characterized in that: When the gas production of the vertical production well or the horizontal production well is less than a preset threshold, the well adjacent to the vertical production well or the horizontal production well is replaced as a production well.

7. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: The preheating of the oil layer through the production well and the gas injection well includes: injecting steam through the production horizontal well to preheat the oil layer by steam huff and puff or circulation preheating; or preheating the oil layer by electric heating.

8. The method of claim 1 for inhibiting edge water intrusion by in-situ oxidation of crude oil, characterized in that: The time required for heating to the preset oxidation temperature t=Q is obtained based on the total heat required for preheating to the preset oxidation temperature and the heating rate 总 / P, where t is time, h, P is heating rate, Q 总 The total amount of heat required for preheating to the preset oxidation temperature; the total amount of heat required for preheating 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 oil layers other than the preheated oil layer.

9. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: The method also includes injecting catalysts, oxidants and other composite additives into the oil layer in the edge water development zone through a gas injection well to promote oxidation reaction between the oxidizing medium and the crude oil in the oil layer in the edge water development zone.

10. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: The preset oxidation temperature is 100-150°C. When the oil layer temperature does not meet the requirement of the preset oxidation temperature, water injection for cooling, steam heating, nitrogen injection for insulation and adjustment of the parameters of the injected medium can be used to adjust the oil layer temperature.

11. The method for inhibiting edge water intrusion by in-situ oxidation of crude oil according to claim 1, characterized in that: After preheating the oil layer to a preset oxidation temperature through production wells and gas injection wells, the method also includes: making the inter-well communication temperature greater than 100° C. and setting the injection-production ratio to above 1.

0.

12. A device for inhibiting edge water intrusion by in-situ oxidation of crude oil, using the method for inhibiting edge water intrusion by in-situ oxidation of crude oil as claimed in any one of claims 1 to 11, characterized in that: include: A combined injection-production well pattern, comprising production wells and gas injection wells, wherein the production wells and the gas injection wells are arranged in an area close to an edge water zone in an oil layer in an edge water development zone; A preheating unit, connected to the production well and the gas injection well, for preheating the oil layer to a preset oxidation temperature through the production well and the gas injection well; A nitrogen injection unit connected to the gas injection well is used to inject nitrogen into the oil layer in the edge water development zone where the pressure drop exceeds a preset threshold or has shown an edge water invasion trend, so as to supplement the formation pressure; The medium injection unit is connected to the gas injection well and is used to inject an oxidizing medium into the oil layer so that the oxidizing medium reacts with the crude oil in the oil layer of the edge water development zone to form a non-flowable colloid-like heavy oil and coke deposition zone inside the interface between the oil layer and the edge water zone.

13. The device for inhibiting edge water intrusion by in-situ oxidation of crude oil as claimed in claim 12, characterized in that: The combined injection-production well network includes gas injection vertical wells and production vertical wells, which are cross-arranged in the oil layer in the edge water development zone near the edge water area. The gas injection vertical wells are used to inject nitrogen and the oxidizing medium into the oil layer, and the production vertical wells are used to produce the associated gas generated by the oxidation reaction.

14. The device for inhibiting edge water intrusion by in-situ oxidation of crude oil as claimed in claim 12, characterized in that: The combined injection-production well network includes production horizontal wells and gas injection horizontal wells. The gas injection horizontal wells are arranged below the production horizontal wells. The gas injection horizontal wells are used to inject nitrogen and the oxidizing medium into the oil layer, and the production horizontal wells are used to produce the associated gas generated by the oxidation reaction.

Images