Method for exploiting thickened oil through multi-medium huff and puff

Abstract

The invention provides a method for exploiting thickened oil through multi-medium huff and puff. The multi-medium huff and puff thickened oil exploitation method comprises the following steps: S1, emulsifying oil added with an emulsifier with aqueous solutions of two reactants capable of generating thermal chemical reactions respectively to obtain two water-in-oil emulsions; and S2, the two emulsions are mixed and then injected into a heavy oil well, the emulsions are gradually demulsified in the stratum and subjected to a thermal chemical reaction, heat and gas are released, the heat and gas released in the reaction and oil in the emulsions are utilized, the flowing capacity of the stratum heavy oil is improved through the effects of dilution viscosity reduction, heating viscosity reduction, gas pressurization and the like, and then the yield of the heavy oil well is increased. Thermal chemical reactant aqueous solutions are emulsified to form emulsions, the emulsions are mixed and injected into a heavy oil well, the two reactant aqueous solutions are mixed in a water-in-oil emulsion state to prevent the reactant aqueous solutions from releasing heat and generating gas due to premature contact reaction, on one hand, ground and shaft heat losses are reduced, and the heat utilization rate is increased; and secondly, the injection safety is improved.

Description

Technical Field

[0001] The present invention relates to a method for multi-medium huff and puff production of heavy oil, belonging to the technical field of oil production. Background Art

[0002] Steam huff and puff is a simple and efficient method for heavy oil production. This method injects high-temperature steam into a heavy oil well and soaks the well, and improves the heavy oil production by heating the heavy oil in the oil reservoir and significantly reducing the viscosity of the heavy oil. However, significant heat loss occurs when the injected high-temperature steam passes through the surface pipeline and the wellbore, reducing the dryness and enthalpy of the steam injected into the oil reservoir. When the oil reservoir of a heavy oil well is relatively deep, serious heat loss will result in low dryness of the steam injected into the oil reservoir and poor steam huff and puff production effect.

[0003] Using thermochemical reactions (such as the reaction between sodium nitrite solution and ammonium chloride or ammonium nitrate solution) to generate heat in the oil reservoir and heat the heavy oil is a method for heavy oil production. Since heat is generated in the oil reservoir, heat loss in the surface pipeline and the wellbore is avoided. However, when the solutions of two reactants are injected successively in sections, the mixing effect in the oil reservoir is not ideal, which will affect the thermochemical reaction effect of the reactants in the oil reservoir; however, if the solutions of the two reactants are mixed in a tank and a pump on the ground, the two reactant solutions will react prematurely, and heat loss in the ground and the wellbore and reduced heat utilization efficiency will still occur, and the generated heat and gas will also pose safety risks to the ground and the wellbore. Therefore, safe and efficient injection is a key issue for heavy oil wells to use thermochemical reactions to heat the oil reservoir.

[0004] The temperature increase range of heating the oil reservoir by using thermochemical reactions is usually lower than 100°C. For extra-heavy oil and super-heavy oil with relatively high viscosity, simply relying on thermochemical reactions to heat the oil reservoir to increase the heavy oil well production is limited. At the same time, injecting solvents and light oil can increase the heavy oil well production by dilution and viscosity reduction. Laboratory studies and field tests at home and abroad have confirmed the feasibility of huff and puff production of heavy oil by injecting solvents or light oil. However, the effect of simply injecting solvents or light oil for huff and puff production of heavy oil will be limited by costs, oil reservoir mixing efficiency, and sweep range, etc. Auxiliary injection of gas and heating can further improve the effect of huff and puff production of heavy oil by solvents or light oil. Summary of the Invention

[0005] The object of the present invention is to provide a method for multi-medium huff and puff production of heavy oil, which emulsifies oil with an emulsifier added on the ground respectively with aqueous solutions of two reactants that can undergo thermochemical reactions to respectively prepare two water-in-oil emulsions, mixes the two emulsions in a certain proportion and then injects them into a heavy oil well, so that the two emulsions gradually break emulsions in the formation and undergo thermochemical reactions, releasing heat and gas, and using the heat and gas released by the reaction and the oil in the emulsion to improve the flowability of the heavy oil in the formation through dilution and viscosity reduction, heating and viscosity reduction, gas pressurization, etc., thereby increasing the production of the heavy oil well.

[0006] According to a specific embodiment of the present invention, the thin oil may be the thin oil produced by an oil production platform, the thin oil produced by other oil production platforms and transported to the present oil production platform through pipelines, or other available thin oils; the thin oil can be injected with chemicals through a chemical metering pump; the thin oil can be heated by a heater. The viscous oil well may be a single viscous oil well or multiple viscous oil wells.

[0007] According to a specific embodiment of the present invention, the oil added with an emulsifier may be an organic solvent, thin oil or other oils with relatively low viscosity. The emulsifier is a mixture of one or more emulsifiers capable of forming a water-in-oil emulsion. The two reactants capable of undergoing a thermal chemical reaction are water-soluble and can react exothermically. In order to control the rate of the exothermic reaction, a certain amount of reaction rate control agent can be added to the solution of one or both of the reactants.

[0008] According to a specific embodiment of the present invention, the volume ratio of the oil added with an emulsifier to the aqueous solution of the reactants is 3:7 to 7:3.

[0009] According to a specific embodiment of the present invention, the emulsion formed by emulsifying the aqueous solutions of the two reactants and the oil added with an emulsifier is mixed in a certain proportion and then injected into the viscous oil well. Preferably, the emulsions of the aqueous solutions of the two reactants and the oil added with an emulsifier are respectively pumped into the same viscous oil well, so that the emulsions of the two reactants are mixed in the wellbore and then injected into the oil reservoir.

[0010] According to a specific embodiment of the present invention, the emulsifier is a mixture of one or more emulsifiers capable of forming a water-in-oil emulsion. Preferably, the emulsifier may be sorbitan fatty acid ester, polyoxyethylene fatty alcohol ether, polyoxyethylene polyfatty alcohol ether, polyglycerol fatty acid ester, etc. Preferably, the mass concentration of the emulsifier added to the oil phase is 0.3 wt% to 0.7 wt%.

[0011] According to a specific embodiment of the present invention, the two reactants capable of undergoing a thermal chemical reaction are water-soluble and can react exothermically. Preferably, one of the two reactants capable of undergoing a thermal chemical reaction is sodium nitrite, and the other reactant is ammonium chloride, ammonium nitrate or a mixture of ammonium chloride and ammonium nitrate; preferably, one of the two reactants capable of undergoing a thermal chemical reaction is sulfuric acid, and the other reactant is a sodium bicarbonate solution, an ammonium bicarbonate solution or a mixture of sodium bicarbonate and ammonium bicarbonate.

[0012] According to a specific embodiment of the present invention, the mass concentration of the reactants in the aqueous solutions of the two reactants capable of undergoing a thermal chemical reaction is 5 wt% to 80 wt%. The preferred reactant concentration varies depending on the type of reactants, the ground temperature conditions, and the underground reaction requirements. The concentrations of the two aqueous reactant solutions should ensure that the molar ratio of the reactants in the water-in-oil emulsion of the two aqueous reactant solutions injected into the heavy oil well satisfies the coefficient ratio of the reactants in the thermal chemical reaction. Preferably, the two reactants capable of undergoing a thermal chemical reaction are sodium nitrite and ammonium nitrate respectively. The volume ratio of oil to water in the prepared emulsion is 3:7, and the volumes of the emulsions of the two aqueous reactant solutions injected are equal. When the mass concentration of the ammonium nitrate aqueous solution is 35 wt%, the mass concentration of the sodium nitrite aqueous solution is 30.2 wt%.

[0013] According to a specific embodiment of the present invention, the volume ratio of the emulsions of the two aqueous reactant solutions injected into the heavy oil well should ensure that the molar ratio of the reactants in the water-in-oil emulsion of the two aqueous reactant solutions injected satisfies the coefficient ratio of the reactants in the thermal chemical reaction. Preferably, the two reactants capable of undergoing a thermal chemical reaction are sodium nitrite and ammonium nitrate respectively. The volume ratio of oil to water in the prepared emulsion is 3:7. When the mass concentration of the ammonium nitrate aqueous solution injected is 35 wt% and the mass concentration of the sodium nitrite aqueous solution is 30.2 wt%, the volumes of the emulsions of the two aqueous reactant solutions injected are equal.

[0014] According to a specific embodiment of the present invention, the reaction rate control agent plays a role in controlling the thermal chemical reaction rate of the reactants. Preferably, when the thermal chemical reactants are sodium nitrite and ammonium nitrate, if it is necessary to reduce the reaction rate of the system, an appropriate amount of alkaline substance can be added as the reaction rate control agent, such as sodium hydroxide, potassium hydroxide, ammonia water, and alkaline ammonium salts such as ammonium bicarbonate, etc.; if it is necessary to increase the reaction rate, an acidic substance can be added as the reaction rate control agent, such as glacial acetic acid.

[0015] According to a specific embodiment of the present invention, the reaction rate control agent can be added to one of the aqueous solutions of the two reactants, or added to the aqueous solutions of the two reactants respectively. Preferably, when the thermal chemical reactants are sodium nitrite and ammonium nitrate, if it is necessary to reduce the reaction rate of the system, sodium hydroxide with a mass concentration of 0.005 wt% can be added to the sodium nitrite aqueous solution.

[0016] The method for multi-medium huff and puff production of heavy oil in the present invention controls the thermal chemical rate and improves the injection safety by forming a water-in-oil emulsion. After demulsification in the underground oil reservoir, heat and gas are released by the reaction. The mobility of the heavy oil in the oil reservoir and the production of the heavy oil well are improved by the action of the solvent or light oil in the emulsion and the heat and gas generated by the reaction. Due to no heat loss on the ground and in the wellbore, in addition to being suitable for conventional heavy oil reservoirs, it is especially suitable for heavy oil reservoirs with relatively deep burial and large heat loss in the steam injection wellbore.

[0017] The present invention has the following beneficial technical effects:

[0018] (1) In the method for multi-medium huff and puff production of heavy oil provided by the present invention, an aqueous solution of a thermochemical reactant is emulsified to form an emulsion and then mixed and injected into a heavy oil well. The two aqueous reactant solutions are mixed in the form of a water-in-oil emulsion to prevent the premature contact and reaction of the aqueous reactant solutions, thus releasing heat and generating gas. First, it reduces the heat loss on the ground and in the wellbore and improves the heat utilization rate; second, it improves the injection safety.

[0019] (2) When the emulsion of the two aqueous reactant solutions injected into the oil reservoir in the method for multi-medium huff and puff production of heavy oil provided by the present invention gradually demulsifies and reacts to release heat and generate gas, together with the solvent or thin oil in the emulsion, it improves the fluidity of the heavy oil and the production of the heavy oil well through the effects of viscosity reduction by heating, viscosity reduction by dilution, pressure increase, and extended sweep range. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the injection process flow of the thermochemical reactant emulsion. The markings in the figure are: 1: storage tank for the emulsion of the aqueous solution of reactant 1, 2: storage tank for the emulsion of the aqueous solution of reactant 2, 3, 4, 5: valves, 6, 7, 8: injection pumps, 9: wellhead, 10: heavy oil well.

[0021] Figure 2 It is a relationship curve between the incremental oil production and the output-input ratio during the multi-medium huff and puff cycle and the injection volume of the reactant emulsion in a deep thick-layer ordinary heavy oil reservoir.

[0022] Figure 3 It is a relationship curve between the incremental oil production and the output-input ratio during the multi-medium huff and puff cycle and the injection volume of the reactant emulsion in a medium-deep thin-layer ordinary heavy oil reservoir.

[0023] Figure 4 It is a relationship curve between the incremental oil production and the output-input ratio during the multi-medium huff and puff cycle and the injection volume of the reactant emulsion in a shallow thin-layer ordinary heavy oil reservoir. Detailed Embodiments

[0024] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods.

[0025] Unless otherwise specified, the materials, reagents, etc. used in the following embodiments can all be obtained through commercial channels.

[0026] Example 1

[0027] In this embodiment, the method for multi-medium huff and puff production of heavy oil of the present invention is used to exploit a deep thin-layer ordinary heavy oil reservoir with horizontal wells deployed. The top depth of the reservoir is 1500 m, the thickness of the oil layer is 30 m, and the viscosity of the in-situ heavy oil is 1000 mPa·s.

[0028] A horizontal and homogeneous heavy oil reservoir model with a size of 425m×200m×30m is adopted. The top depth of the reservoir is 1500m, the thickness is 30m, and 1 horizontal well is deployed in parallel. The length of the horizontal well is 300m, and it is deployed at a position 5.0m away from the bottom of the oil layer. The specific reservoir parameters are shown in Table 1. A homogeneous reservoir geological model with 17×45×15 grids is established. The size of the grid in the X direction is 25m, the size in the Y direction is 2 - 7.5m, and the size in the Z direction is 2m.

[0029] Table 1 Geological parameters of deep and thick heavy oil reservoirs

[0030] Item Value Deep reservoir layer (m) 1500 Reservoir model length (m) 425 Reservoir model width (m) 200 Reservoir model thickness (m) 30 Porosity 0.33 Horizontal permeability (mD) 1500 Vertical permeability / Horizontal permeability 0.75 Viscosity of heavy oil in formation (mPa·s) 2000 Initial oil saturation 0.65 Initial reservoir temperature (℃) 50 Initial reservoir pressure (MPa) 15

[0031] In this embodiment, when multi - medium huff and puff is used to exploit deep and thick heavy oil reservoirs, multi - medium huff and puff is simulated through reservoir numerical simulation at different stages of exploitation, and the injection - production cycle of each period is 0.5 years. The injection media are two reactants that can undergo thermal chemical reactions, namely sodium nitrite and ammonium nitrate. The volume ratio of oil to water in the prepared emulsion is 3:7, and the volumes of the emulsions injected with the two reactant aqueous solutions are equal. The mass concentration of the ammonium nitrate aqueous solution is 35wt%, then the mass concentration of the sodium nitrite aqueous solution is 30.2wt%. The oil phase in the emulsion is solvent oil or light oil with a viscosity of 5mPa·s at 55°C, the emulsifier is sorbitan fatty acid ester, and the addition concentration of the emulsifier in the solvent oil is 1.0wt%. The molar ratio of the reactants in the mixture of the two reactant emulsions injected is 1:1, the reaction heat - release capacity is 293.0KJ / mol, and the soaking time is 3 days. The production flowing pressure during the multi - medium huff and puff oil production process is the same as that during the cold production process.

[0032] The STARS thermal recovery simulator of CMG company is used to carry out the simulation calculation of multi - medium huff and puff at different times (i.e., at different recovery rates of 0% - 30%) for cold production of horizontal wells in deep and thick heavy oil reservoirs. The calculation results of the predicted production parameters are shown in Table 2. The mixture of the two reactant emulsions injected per cycle is 3000m 3 . It can be seen that obvious oil - increasing effects have been achieved by implementing multi - medium huff and puff at different times relying on natural energy for cold production. The oil increase per cycle reaches 3167.0m 3 ~4131.1m 3 . Calculated at a cost of 1400 yuan per cubic meter of reactant emulsion (considering the price difference between the solvent or light oil in the emulsion and the produced heavy oil, emulsifier cost, preparation cost and injection cost, and the oil price is taken as 70 US dollars / barrel), the output - input ratio of multi - medium huff and puff for deep and thick heavy oil reservoirs in this embodiment reaches 2.501 - 3.263. Moreover, the earlier the multi - medium huff and puff is implemented (i.e., the lower the recovery rate), the better the oil - increasing effect and the higher the output - input ratio of multi - medium huff and puff.

[0033] Table 2 Numerical simulation prediction of injection-production parameters for multi-medium huff and puff of horizontal wells in deep and thick heavy oil reservoirs at different times

[0034]

[0035] Using the STARS thermal recovery simulator of CMG, simulation calculations of multi-medium huff and puff were carried out for horizontal wells in deep and thick conventional heavy oil reservoirs with different injection amounts of reactant emulsions (1000 m 3 ~5000 m 3 , that is, the injection intensity is 3.3~16.7 m 3 / m well section). The calculation results of the predicted production parameters are shown in Table 3, and the injection time is when the recovery factor is 0. The relationship curve between the incremental oil production per cycle of multi-medium huff and puff and the injection amount of reactant emulsion per cycle is as Figure 2 shown. It can be seen that for the multi-medium huff and puff of deep and thick heavy oil in this embodiment, the reasonable injection amount of reactant emulsion per cycle is 2000 m 3 ~3000 m 3 , and the reasonable injection intensity of reactant emulsion per cycle for the horizontal well is 6.67~10 m 3 / m well section.

[0036] Table 3 Numerical simulation prediction of injection-production parameters for multi-medium huff and puff of horizontal wells in deep and thick heavy oil reservoirs at different times

[0037]

[0038]

[0039] Example 2,

[0040] In this example, the multi-medium huff and puff method for heavy oil production of the present invention was used to develop a medium-deep and thin-layer conventional heavy oil reservoir with horizontal wells deployed. The top depth of the reservoir is 1000 m, the oil layer thickness is 10 m, and the viscosity of the formation heavy oil is 2000 mPa·s.

[0041] A horizontal, homogeneous heavy oil reservoir model with a size of 425 m×200 m×10 m was used. The top depth of the reservoir is 1000 m, the thickness is 10 m, and 1 horizontal well is deployed in parallel. The length of the horizontal well is 300 m, and it is deployed 1.5 m from the bottom of the oil layer. The specific reservoir parameters are shown in Table 4. A homogeneous reservoir geological model with 17×45×10 grids was established. The size of the grid in the X direction is 25 m, the size in the Y direction is 2~7.5 m, and the size in the Z direction is 1 m.

[0042] Table 4 Geological parameters of medium-deep and thin-layer conventional heavy oil reservoirs

[0043] Item Value Deep reservoir layer (m) 1000 Reservoir model length (m) 425 Reservoir model width (m) 200 Reservoir model thickness (m) 10 Porosity 0.33 Horizontal permeability (mD) 1500 Vertical permeability / Horizontal permeability 0.75 Viscosity of heavy oil in formation (mPa·s) 2000 Initial oil saturation 0.65 Initial reservoir temperature (℃) 50 Initial reservoir pressure (MPa) 10

[0044] In this embodiment, when multi-media huff and puff is used to exploit medium-deep and thin-layered conventional heavy oil reservoirs, numerical simulation of the reservoir is carried out for multi-media huff and puff at different production stages, and the injection-production cycle for each period is 0.5 year. The injection media are two reactants that can undergo thermochemical reactions, namely sodium nitrite and ammonium nitrate. The volume ratio of oil to water in the prepared emulsion is 3:7 for both, and the volumes of the emulsions of the two reactant aqueous solutions injected are equal. The mass concentration of the ammonium chloride aqueous solution is 23.4 wt%, and then the mass concentration of the sodium nitrite aqueous solution is 30.2 wt%. The oil phase in the emulsion is solvent oil with a viscosity of 10 mPa·s at 50 °C, the emulsifier is polyoxyethylene fatty alcohol ether, and the addition concentration of the emulsifier in the solvent oil is 0.5 wt%. The molar ratio of the reactants in the mixture of the emulsions of the two reactants injected is 1:1, the heat release capacity of the reaction is 332.6 KJ / mol, and the shut-in time is 4 days. The flowing bottomhole pressure during the multi-media huff and puff oil production process is the same as that during the cold production process.

[0045] The STARS thermal recovery simulator of CMG company was used to carry out simulation calculations on multi-media huff and puff at different times (i.e., at different recovery rates of 0% to 30%) for cold production of horizontal wells in medium-deep and thin-layered conventional heavy oil reservoirs. The calculation results of the predicted production parameters are shown in Table 5. The mixture of the emulsions of the two reactants injected in each cycle is 2500 m 3 . It can be seen that obvious oil production increase effects have been achieved by implementing multi-media huff and puff at different times relying on natural energy, and the oil production increase per cycle reaches 1459.8 m 3 ~3556.5 m 3 . Calculated at a cost of 1400 yuan per cubic meter of the reactant emulsion (considering the price difference between the solvent or light oil in the emulsion and the produced heavy oil, the cost of the emulsifier, the preparation cost and the injection cost, and the oil price is taken as 70 US dollars / barrel), the output-input ratio of multi-media huff and puff in the medium-deep and thick-layered conventional heavy oil reservoir in this embodiment reaches 1.384 to 3.371. Moreover, the earlier the timing of implementing multi-media huff and puff (i.e., the lower the recovery rate), the better the oil production increase effect and the higher the output-input ratio. When the cold production recovery rate of the medium-deep and thin-layered heavy oil reservoir reaches more than 20%, it is not suitable to implement the multi-media huff and puff of the present invention.

[0046] Table 5 Numerical simulation prediction of injection-production parameters for multi-media huff and puff of horizontal wells in medium-deep and thin-layered heavy oil reservoirs at different times

[0047]

[0048] The STARS thermal recovery simulator of CMG company was used to carry out the injection volume of the mixture of different reactant emulsions (1500 m 3 ~3500 m 3 , that is, the injection intensity is 5.0 to 11.7 m 3Perform simulation calculations for multi-media huff and puff in the [[ / m well section]], and the calculated results of the predicted production parameters are shown in Table 6. The injection timing is when the recovery factor is 0. The relationship curve between the incremental oil production per cycle of multi-media huff and puff and the injection volume of the periodic reactant emulsion is as Figure 3 shown. It can be seen that for the reasonable injection volume of the periodic reactant emulsion in the multi-media huff and puff of medium-deep and thin-layer heavy oil in this embodiment, it is 2000 m 3 ~2500 m 3 , and the reasonable injection intensity of the periodic reactant emulsion for the converted horizontal well is 6.67~8.33 m 3 / m well section.

[0049] Table 6 Numerical simulation prediction of injection-production parameters for multi-media huff and puff at different times in horizontal wells of medium-deep and thin-layer heavy oil reservoirs

[0050]

[0051] Example 3,

[0052] In this embodiment, the method for exploiting heavy oil by multi-media huff and puff of the present invention is used to exploit and deploy a shallow and thin-layer common heavy oil reservoir of a horizontal well. The top depth of the reservoir is 500 m, the thickness of the oil layer is 10 m, and the viscosity of the formation heavy oil is 3000 mPa·s.

[0053] A horizontal, homogeneous heavy oil reservoir model with a size of 425 m×200 m×10 m is adopted. The top depth of the reservoir is 500 m, the thickness is 10 m, and 1 horizontal well is deployed in parallel. The length of the horizontal well is 300 m, and it is deployed at a position 5.0 m away from the bottom of the oil layer. The specific reservoir parameters are shown in Table 7. A homogeneous reservoir geological model with 17×45×10 grids is established. The size of the grid in the X direction is 25 m, the size in the Y direction is 2~7.5 m, and the size in the Z direction is 1 m.

[0054] Table 7 Geological parameters of shallow and thin-layer common heavy oil reservoirs

[0055] Item Value Deep reservoir layer (m) 500 Reservoir model length (m) 425 Reservoir model width (m) 200 Reservoir model thickness (m) 30 Porosity 0.33 Horizontal permeability (mD) 1500 Vertical permeability / Horizontal permeability 0.75 Viscosity of heavy oil in formation (mPa·s) 3000 Initial oil saturation 0.65 Initial reservoir temperature (℃) 40 Initial reservoir pressure (MPa) 5

[0056] In this embodiment, when multi-medium huff and puff is used to exploit shallow and thin ordinary heavy oil reservoirs, multi-medium huff and puff is carried out at different stages of exploitation through reservoir numerical simulation, and the injection-production cycle of each cycle is 0.5 years. The injection media are two reactants that can undergo thermochemical reactions, namely sodium nitrite and ammonium nitrate. The volume ratio of oil to water in the prepared emulsion is 3:7, and the volume of the emulsion injected with the two reactant aqueous solutions is equal. The mass concentration of the ammonium nitrate aqueous solution is 35 wt%, and the mass concentration of the sodium nitrite aqueous solution is 30.2 wt%. The oil phase in the emulsion is solvent oil with a viscosity of 5 mPa·s at 55 °C, the emulsifier is sorbitan fatty acid ester, and the addition concentration in the solvent oil is 0.5 wt%. The molar ratio of the reactants in the mixture of the two reactant emulsions injected is 1:1, and the well is shut in for 3 days. The production flow pressure in the process of multi-medium huff and puff oil production is the same as the flow pressure in the cold production process.

[0057] The STARS thermal recovery simulator of CMG company was used to carry out the simulation calculation of multi-medium huff and puff at different times (i.e., at different recovery rates of 0% - 15%) for horizontal wells in shallow and thin ordinary heavy oil reservoirs. The calculation results of the predicted production parameters are shown in Table 8. The mixture of the two reactant emulsions injected in each cycle is 2000 m 3 . It can be seen that obvious oil production increase effects have been achieved by implementing multi-medium huff and puff at different times relying on natural energy cold production, and the oil production increase per cycle reaches 1007.1 m 3 ~1791.0 m 3 . Calculated at the cost of 1400 yuan per cubic meter of reactant emulsion (considering the price difference between the solvent or light oil in the emulsion and the produced heavy oil, the cost of the emulsifier, the preparation cost and the injection cost, and the oil price is taken as 70 US dollars / barrel), the output-input ratio of multi-medium huff and puff in the shallow and thin ordinary heavy oil reservoirs in this embodiment reaches 1.193 - 2.122. Moreover, the earlier the multi-medium huff and puff is implemented (i.e., the lower the recovery rate), the better the oil production increase effect and the higher the output-input ratio. When the cold production recovery rate of the shallow and thin heavy oil reservoir reaches more than 10%, it is not suitable to implement the multi-medium huff and puff of the present invention, or reduce the injection volume of the reactant emulsion per cycle.

[0058] Table 8 Numerical simulation prediction of injection-production parameters for multi-medium huff and puff at different times for horizontal wells in shallow and thin ordinary heavy oil reservoirs

[0059]

[0060] The STARS thermal recovery simulator of CMG company was used to carry out the injection volume of the mixture of different reactant emulsions for horizontal wells in shallow and thin ordinary heavy oil reservoirs (1000 m 3 ~3000 m 3 , that is, the injection intensity is 3.3 - 10.0 m 3The simulation calculation of multi-medium huff and puff is carried out for the Figure 4 / m interval), and the calculation results of the predicted production parameters are shown in Table 9. The injection timing is when the recovery factor is 0. The relationship curve between the incremental oil production per cycle of multi-medium huff and puff and the injection volume of the periodic reactant emulsion is as 3 shown. It can be seen that for the shallow and thin-layer ordinary heavy oil reservoir in this embodiment, the reasonable injection volume of the periodic reactant emulsion for multi-medium huff and puff is 1500 m 3 ~2000 m 3 , and the reasonable injection intensity of the periodic reactant emulsion for the converted horizontal well is 5.0 - 6.7 m

[0061] / m interval.

[0062]

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing heavy oil by multi-media throughput, comprising the following steps: S1, emulsifying the oil to which the emulsifier is added with the aqueous solutions of two reactants capable of undergoing thermochemical reactions, respectively, to obtain two water-in-oil emulsions; S2, mixing the two emulsions and injecting them into a heavy oil well, so that they gradually break the emulsions in the formation and undergo a thermochemical reaction to release heat and gas, and utilizing the heat and gas released by the reaction and the oil in the emulsion to increase the production of the heavy oil well.

2. The method according to claim 1, characterized in that: The oil is an organic solvent or thin oil; The reactants capable of thermochemical reaction are water-soluble and can react to release heat; A reaction rate control agent is added to one or both of the thermochemically reactive reactants.

3. The method for producing heavy oil by using a multi-media throughput method according to claim 1 or 2, characterized in that: The volume ratio of the oil to which the emulsifier is added to the aqueous solution of the two reactants capable of undergoing thermochemical reactions is 3:7 to 7:

3.

4. The multi-media throughput method for heavy oil production according to any one of claims 1 to 3, characterized in that: The emulsions formed by emulsifying the aqueous solutions of the two reactants capable of undergoing thermochemical reactions and the oil with the added emulsifier are respectively injected into the same heavy oil well, and the emulsions of the two reactants are mixed in the wellbore and then injected into the oil layer.

5. The multi-media throughput method for heavy oil production according to any one of claims 1 to 4, characterized in that: The emulsifier is one or more of sorbitan fatty acid ester, polyoxyethylene fatty alcohol ether, polyoxyethylene polyfatty alcohol ether and polyglycerol fatty acid ester; The mass concentration of the emulsifier is 0.3% to 0.7%.

6. The multi-media throughput method for heavy oil production according to any one of claims 1 to 5, characterized in that: The two thermochemically reactive reactants are the following 1) or 2): 1) One of the reactants capable of undergoing a thermochemical reaction is sodium nitrite, and the other of the reactants capable of undergoing a thermochemical reaction is ammonium chloride, ammonium nitrate, or a mixture of ammonium chloride and ammonium nitrate; 2) One of the reactants capable of undergoing a thermochemical reaction is sulfuric acid, and the other reactant capable of undergoing a thermochemical reaction is a sodium bicarbonate solution, an ammonium bicarbonate solution, or a mixture of sodium bicarbonate and ammonium bicarbonate.

7. The multi-media throughput method for heavy oil production according to any one of claims 1 to 6, characterized in that: The mass concentration of the reactants in the two aqueous solutions of the reactants capable of undergoing thermochemical reactions is 5% to 80%; The two reactants capable of undergoing thermochemical reaction are sodium nitrite and ammonium nitrate, respectively. The prepared emulsions have an oil-water volume ratio of 3:

7. The volumes of the emulsions injected with the two aqueous solutions of the reactants are equal. The mass concentration of the ammonium nitrate aqueous solution is 35%, and the mass concentration of the sodium nitrite aqueous solution is 30.2%.

8. The multi-media throughput method for heavy oil production according to any one of claims 1 to 7, characterized in that: The two reactants capable of undergoing thermochemical reaction are sodium nitrite and ammonium nitrate, the prepared emulsions have an oil-water volume ratio of 3:7, the injected ammonium nitrate aqueous solution has a mass concentration of 35%, and the sodium nitrite aqueous solution has a mass concentration of 30.2%, and the volumes of the emulsions injected of the two reactant aqueous solutions are equal.

9. The multi-media throughput method for heavy oil production according to any one of claims 1 to 8, characterized in that: The reaction rate controller plays a role in controlling the thermochemical reaction rate of the reactants; When the thermochemical reactants are sodium nitrite and ammonium nitrate, if the reaction rate of the system is to be reduced, the reaction rate controller is an alkaline substance; if the reaction rate is to be increased, the reaction rate controller is an acidic substance.

10. The multi-media throughput method for heavy oil production according to any one of claims 1 to 9, characterized in that: The reaction rate controller is added to one of the two aqueous reactant solutions, or is added to the two aqueous reactant solutions separately.

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