Method for determining fire-flood permeability and crude oil viscosity development limits

Abstract

This invention provides a method for determining the development limits of fire-driven permeability and crude oil viscosity. The method includes: conducting a fire-driven permeability model experiment using a combustion tube fire-driven permeability model system to obtain preliminary development limit ranges for fire-driven permeability and crude oil viscosity; conducting multiple core thermal effect monitoring experiments using a core thermal effect monitoring system to obtain precise development limit ranges for fire-driven permeability and crude oil viscosity; and correlating the preliminary and precise development limit ranges for fire-driven permeability and crude oil viscosity to obtain the final development limit ranges for fire-driven permeability and crude oil viscosity. The method for determining the development limits of fire-driven permeability and crude oil viscosity provided by this invention can accurately determine these limits.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to a method for determining the development limits of fire-driven permeability and crude oil viscosity. Background Technology

[0002] The complex physicochemical reactions occurring in the porous media of the oil reservoir during fire flooding, along with their properties, reaction rates, and heat of formation, significantly influence the process and its effectiveness. This also places high demands on fire flooding technology and presents significant challenges for field operation. In recent years, researchers have conducted numerous physical simulation experiments using combustion tubes. These experiments effectively determine whether heavy oil can be ignited at a given ignition temperature, calculate fundamental parameters during fire flooding such as fuel consumption, oil displacement efficiency, and oxygen utilization, and perform parameter sensitivity analysis. However, research on physical simulation experiments for fire flooding in low-permeability heavy oil reservoirs remains lacking.

[0003] Although domestic and international literature has reported screening criteria for fire-driven thermal recovery, the ranges given largely depend on different reservoir data, field experience, and numerical simulation results, resulting in a wide range and even significant discrepancies between different studies. Currently, there is a lack of rigorous and systematic experimental methods to accurately and effectively evaluate the impact of key parameters (such as permeability and crude oil viscosity) on the effectiveness of fire-driven development. Therefore, it is essential to design a method for determining the development limits of permeability and crude oil viscosity in fire-driven thermal recovery. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the development limits of fire-driven permeability and crude oil viscosity, which can accurately determine the development limits of fire-driven permeability and crude oil viscosity.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A method for determining the development limits of permeability and crude oil viscosity in fire-driven flooding is applied to a system for determining and obtaining the development limits of permeability and crude oil viscosity. The system includes: a combustion tube fire-driven flooding physical model experimental system and a core thermal effect monitoring experimental system.

[0007] The method includes the following steps:

[0008] Step 1: Conduct a combustion tube fire drive physical model experiment based on the combustion tube fire drive physical model experimental system to obtain the preliminary development limit range of fire drive permeability and crude oil viscosity;

[0009] Step 2: Conduct multiple core thermal effect monitoring experiments based on the core thermal effect monitoring experimental system to obtain the precise development limits of fire-driven permeability and crude oil viscosity;

[0010] Step 3: Correlate the preliminary development limits of fire-driven permeability and crude oil viscosity with the precise development limits of fire-driven permeability and crude oil viscosity to obtain the final development limits of fire-driven permeability and crude oil viscosity.

[0011] Optionally, in step 1, a combustion tube fire-drive physical model experiment is conducted based on the combustion tube fire-drive physical model experimental system to obtain the preliminary development limits of fire-drive permeability and crude oil viscosity. This specifically includes the following steps:

[0012] Step 101: Mix oil, water and sand thoroughly and fill them into the combustion tube. Each time, fill a small amount of the mixture in equal quantities and compact it with a sand-pressing device. Apply a certain pressure and compaction time until the mixture is filled to the sealing section of the combustion tube.

[0013] Step 102: Install the sealing flange, igniter, temperature monitoring probe and heater according to the combustion tube fire-driven physical model experimental system, and fill the annular space in the combustion tube and pressure sleeve with aluminum silicate to reduce heat loss during the reaction process.

[0014] Step 103: Check the airtightness of the system. After the check is completed, measure the nitrogen permeability of the combustion tube using a soap film flow meter. After the measurement is completed, seal the real-time pressure chamber of the combustion tube. After sealing, conduct an ignition test. After the test is completed, inject nitrogen to extinguish the fire. The experiment is completed, and the preliminary development limit range of fire-driven permeability and crude oil viscosity is obtained.

[0015] Optionally, in step 2, multiple core thermal effect monitoring experiments are conducted based on the core thermal effect monitoring experimental system to obtain the precise development limits for fire-driven permeability and crude oil viscosity. Specific steps include:

[0016] Step 201: Insert the thermocouple into the injection end of the quartz reactor, inject quartz sand from the outlet end to the injection end, and inject silica gel particles into the quartz reactor, wherein the head of the thermocouple is located at the center of the silica gel particle block.

[0017] Step 202: Obtain the core and saturate it with oil and water. Measure the core permeability using a soap film flow meter and place the measured core into a quartz reactor.

[0018] Step 203: Fill the remaining space in the quartz reactor with quartz sand. After filling, place another thermocouple at the center of the quartz reactor to test the core temperature. Heat the quartz reactor with a ceramic heater and inject air into the injection end of the transparent quartz reactor to conduct experiments and obtain the precise development limits of fire-driven permeability and crude oil viscosity.

[0019] Optionally, the filling length of the quartz sand injected from the outlet end to the injection end is 5cm, and the filling length of the silica gel particles is 2.5cm.

[0020] Optionally, the core sample has a diameter of 1.9 cm and a length of 10 cm.

[0021] According to specific embodiments provided by the present invention, the following technical effects are disclosed: The method for determining the development limits of fire-driven permeability and crude oil viscosity provided by the present invention includes conducting a fire-driven permeability model experiment based on a combustion tube fire-driven permeability model experimental system to obtain a preliminary development limit range of fire-driven permeability and crude oil viscosity; conducting multiple core thermal effect monitoring experiments based on a core thermal effect monitoring experimental system to obtain a precise development limit range of fire-driven permeability and crude oil viscosity; and correlating the preliminary development limit range of fire-driven permeability and crude oil viscosity with the precise development limit range of fire-driven permeability and crude oil viscosity to obtain a final development limit range of fire-driven permeability and crude oil viscosity. The method effectively correlates the combustion tube and core thermal effect monitoring results to derive the final development limits of fire-driven permeability and crude oil viscosity, which is of great significance for guiding air injection development in oil fields. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the method for determining the development limits of fire-driven permeability and crude oil viscosity according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the combustion tube fire-driven experimental model system.

[0025] Figure 3 The temperature change curves at different thermocouples during the fire-driven operation of heavy oil A at 300mD are shown.

[0026] Figure 4 The temperature change curves at different thermocouples during the fire-driven operation of heavy oil A at 480mD are shown.

[0027] Figure 5 The temperature change curves at different thermocouples during the fire-driven operation of heavy oil A at 650mD are shown.

[0028] Figure 6This is a schematic diagram of the core thermal effect monitoring experimental system.

[0029] Figure 7 The temperature change curves of samples during the combustion of heavy oil A at 300, 360, 400 and 480 mD are shown.

[0030] Figure 8 The temperature change curves at different thermocouples during the fire-driven operation of heavy oil at 480mD;

[0031] Figure 9 The temperature change curves at different thermocouples during the fire-driven operation of heavy oil at 480mD;

[0032] Figure 10 A comparison of sample temperature curves during the combustion of heavy oil. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a method for determining the development limits of fire-driven permeability and crude oil viscosity, which can accurately determine the development limits of fire-driven permeability and crude oil viscosity.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown in the figure, the method for determining the development limits of permeability and crude oil viscosity in fire-driven flooding provided by the embodiments of the present invention is applied to a system for determining and obtaining the development limits of permeability and crude oil viscosity. This system includes: a combustion tube fire-driven flooding physical model experimental system and a core thermal effect monitoring experimental system. The combustion tube fire-driven flooding physical model experimental system adopts the existing combustion tube fire-driven flooding physical model experimental system. One specific embodiment of the present invention is as follows: Figure 2 As shown, the combustion tube fire-driven experimental model system also includes a sand-pressing device, which can be a conventional sand-pressing device in the prior art. The core thermal effect monitoring experimental system adopts a core thermal effect monitoring experimental system in the prior art. One embodiment provided by the present invention is specifically as follows: Figure 6 As shown;

[0037] like Figure 1 As shown, the method includes the following steps:

[0038] Step 1: Conduct a combustion tube fire drive physical model experiment based on the combustion tube fire drive physical model experimental system to obtain the preliminary development limit range of fire drive permeability and crude oil viscosity;

[0039] Step 2: Conduct multiple core thermal effect monitoring experiments based on the core thermal effect monitoring experimental system to obtain the precise development limits of fire-driven permeability and crude oil viscosity;

[0040] Step 3: Correlate the preliminary development limits of fire-driven permeability and crude oil viscosity with the precise development limits of fire-driven permeability and crude oil viscosity to obtain the final development limits of fire-driven permeability and crude oil viscosity.

[0041] In step 1, a fire-drive physical model experiment is conducted based on the combustion tube fire-drive physical model experimental system to obtain the preliminary development limits of fire-drive permeability and crude oil viscosity. This includes the following steps:

[0042] Step 101: Mix oil, water and sand thoroughly and fill them into the combustion tube. Each time, fill a small amount of the mixture in equal quantities and compact it with a sand-pressing device. Apply a certain pressure and compaction time until the mixture is filled to the sealing section of the combustion tube.

[0043] Step 102: Install the sealing flange, igniter, temperature monitoring probe and heater according to the combustion tube fire-driven physical model experimental system, and fill the annular space in the combustion tube and pressure sleeve with aluminum silicate to reduce heat loss during the reaction process.

[0044] Step 103: Check the airtightness of the system. After the check is completed, measure the nitrogen permeability of the combustion tube using a soap film flow meter. After the measurement is completed, seal the real-time pressure chamber of the combustion tube. After sealing, conduct an ignition test. After the test is completed, inject nitrogen to extinguish the fire. The test is completed, and the preliminary development limit range of fire-driven permeability and crude oil viscosity is obtained.

[0045] Due to the time-consuming, material-intensive, and labor-intensive nature of combustion tube experiments, as well as the unpredictable permeability of porous media, it is impossible to conduct a large number of combustion tube experiments to obtain accurate permeability and crude oil viscosity development ranges. To solve this problem, it is necessary to conduct core thermal effect monitoring experiments that include more permeability and crude oil viscosity, and further refine the development boundaries for permeability and crude oil viscosity.

[0046] In step 2, multiple core thermal effect monitoring experiments are conducted based on the core thermal effect monitoring experimental system to obtain the precise development limits for fire-driven permeability and crude oil viscosity. Specific steps include:

[0047] Step 201: Insert the thermocouple into the injection end of the quartz reactor, inject quartz sand from the outlet end to the injection end, and inject silica gel particles into the quartz reactor, wherein the head of the thermocouple is located at the center of the silica gel particle block.

[0048] Step 202: Obtain the core and saturate it with oil and water. Measure the core permeability using a soap film flow meter and place the measured core into a quartz reactor.

[0049] Step 203: Fill the remaining space in the quartz reactor with quartz sand. After filling, place another thermocouple at the center of the quartz reactor to test the core temperature. Heat the quartz reactor with a ceramic heater and inject air into the injection end of the transparent quartz reactor to conduct experiments and obtain the precise development limits of fire-driven permeability and crude oil viscosity.

[0050] The filling length of the quartz sand injected from the outlet to the injection end is 5cm, and the filling length of the silica gel particles is 2.5cm.

[0051] The core sample has a diameter of 1.9 cm and a length of 10 cm.

[0052] The specific implementation method described in step 3 is shown in the specific embodiment. The present invention provides an embodiment as follows:

[0053] 1. Conduct combustion tube fire-driven physical model experiments:

[0054] S1: Mix oil, water, and sand thoroughly, and then fill the combustion tube. To achieve different permeability, fill the oil, water, and sand mixture according to the following methods. This embodiment provides three schemes, but is not limited to these.

[0055] The first set: 100g of mixture is filled in each time, and then it is compacted with a sand press device. The pressure is 40MPa and the compaction time is 20 minutes. This process is repeated until the sand is filled to the sealing section of the combustion tube, at which point the sand filling is stopped.

[0056] The second set: each time, fill in 200g of the mixture, apply a pressure of 40MPa, and compact for 10 minutes, repeating this process;

[0057] The third set: Each time, fill in 200g of the mixture, apply a pressure of 20MPa, and compact for 10 minutes, repeating this process.

[0058] S2: Install sealing flange, igniter, temperature monitoring probe and heater according to the combustion tube fire-driven physical model experimental system, and fill aluminum silicate into the annular space in the combustion tube and pressure sleeve to reduce heat loss during the reaction process.

[0059] S3: Check the airtightness of the device;

[0060] S4: The nitrogen permeability of the combustion tube was measured using a soap film flow meter. After implementing the first to third sand filling schemes, the obtained gas permeability was 300, 480 and 650 mD, respectively.

[0061] S5: Implement pressure chamber sealing for the combustion tube;

[0062] S6: Conduct an ignition test. Set the igniter temperature to 400℃. Once the ignition temperature is reached, immediately open the outlet and inject air (injection rate: 3L / min). Observe the propagation of the combustion heat front and record the displacement pressure difference and product gas composition data in real time.

[0063] S7: Inject nitrogen gas to extinguish the fire and end the experiment.

[0064] in, Figures 3-5 The figures show temperature change curves at different thermocouple locations during fire-driven combustion of heavy oil A at 300, 480, and 650 mD. These curves reveal that at 300 mD, heavy oil A struggles to achieve a stable and continuous forward propagation of the combustion front with a single ignition; at 480 mD, the combustion front can propagate stably and continuously; and at 650 mD, the combustion front can propagate stably and continuously, with a higher peak combustion temperature than at 480 mD. Therefore, the lower limit for the permeability development of heavy oil A is 300-480 mD. This range is clearly too broad. However, due to the time, material, and labor-intensive nature of combustion tube experiments, and the difficulty in obtaining precise permeability data, it is impossible to conduct numerous combustion tube experiments to determine a precise permeability development range. To address this issue, core thermal effect monitoring experiments are needed to further refine the permeability development limits.

[0065] 2. Conduct core thermal effect monitoring experiments.

[0066] K1: Insert the thermocouple into the injection end of the quartz reactor, fill the injection end with quartz sand (filling length of 5cm) from the outlet end, and then fill the reactor with silica gel particles with a filling length of 2.5cm. The thermocouple head should be located at the center of the silica gel particle block.

[0067] K2: Place a saturated, well-drilled core (diameter: 1.9 cm, length: 10 cm) into the quartz reactor. Note: Before placing the core into the quartz reactor, use a soap film flow meter to measure the core permeability. Finally, select cores with permeability of 300, 360, 400, and 480 mD corresponding to the combustion tube experiment described above.

[0068] K3: Load silica gel granules with a filling length of 2.5cm into the reactor;

[0069] K4: Fill the remaining space in the reactor with quartz sand;

[0070] K5: After filling, place another thermocouple at the center of the reaction sample to test the temperature at the reaction sample.

[0071] K6: A ceramic heater is used to heat the transparent quartz reactor, and air is injected at the injection end of the transparent quartz reactor;

[0072] The air flow rate was 0.25 L / min, and the heating program was set to heat from room temperature to 50°C at 10°C / min, hold the temperature for 10 minutes, and then heat to 700°C at 10°C / min. The air injection and heating started simultaneously, and the changes in the composition of the produced gas were monitored in real time during the reaction.

[0073] according to Figure 3 , Figure 4 and Figure 7 The difference in combustion heat release at 300 and 480 mD in the core thermal effect monitoring experiment showed a high degree of agreement with the combustion tube experiment results at 300 and 480 mD. Therefore, based on the combustion tube experiment results, cores with permeability in the range of 300~480 mD can be selected to carry out thermal effect monitoring experiments. In this embodiment, cores with permeability of 360 and 400 mD were selected, but in practice, it is not limited to this.

[0074] like Figure 7 As shown, when the permeability increases from 300 mD to 360 mD, the oxidation induction period is significantly shortened, but the peak temperature of the sample only increases by 5 °C, and the combustion exothermic effect remains weak. When the permeability is greater than 360 mD, the oxidation induction period no longer changes significantly, but the combustion exothermic effect increases significantly with the increase of permeability. At 400 mD, the peak temperature of the sample during combustion is 567 °C, which is 70 °C higher than that at 300 mD and only 29 °C lower than that at 480 mD. Based on the above results, it can be concluded that fire flooding at 400 and 480 mD has similar combustion exothermic effects and can establish a relatively stable combustion front. Combining the results of combustion tube and core thermal effect monitoring experiments, the lower limit of the permeability development range for heavy oil A is 360~400 mD.

[0075] Similarly, by conducting combustion tube and core thermal effect monitoring experiments on crude oils of different viscosities, the development limits of crude oil viscosity for fire-driven operations can be determined. Figure 8 and Figure 9The figures show the temperature change curves at different thermocouples during fire flooding of heavy oils B and C at 480 mD. The viscosities of heavy oils A, B, C, and D at 50℃ are 444, 7431, 20519, and 9124 mPa·s, respectively. The results indicate that heavy oils A and B can establish a combustion front and the combustion front can be stably transmitted, while heavy oil C cannot. At 480 mD, heavy oils (viscosities between 444 and 7431 mPa·s at 50℃) hold promise for successful fire flooding. Based on these results, further core thermal effect monitoring experiments on crude oils of different viscosities will be conducted, such as... Figure 10 As shown, the peak temperatures of heavy oil samples A and B are approximately 100°C higher than those of heavy oils C and D. This result indicates that C and D exhibit lower exothermic combustion at 480 mD. It is precisely because of this lower exothermic combustion at 480 mD that the combustion leading edge of heavy oil C cannot propagate stably forward during fire-driven combustion. Figure 9 As shown;

[0076] Based on the combined results of combustion tube and core thermal effect monitoring experiments, the upper limit of crude oil viscosity development for fire-driven crude oil at 480mD is 7431~9124mPa·s (at 50℃). Further, heavy oil with a viscosity between 7431 and 9124mPa·s at 50℃ can be selected for core thermal effect monitoring experiments to obtain a more accurate limit of crude oil viscosity development for fire-driven crude oil.

[0077] This invention provides a method for determining the development limits of fire-driven permeability and crude oil viscosity. The method includes conducting a fire-driven permeability model experiment based on a combustion tube fire-driven permeability model system to obtain preliminary development limit ranges for fire-driven permeability and crude oil viscosity; conducting multiple core thermal effect monitoring experiments based on a core thermal effect monitoring experiment system to obtain precise development limit ranges for fire-driven permeability and crude oil viscosity; and correlating the preliminary and precise development limit ranges for fire-driven permeability and crude oil viscosity to obtain the final development limit ranges for fire-driven permeability and crude oil viscosity. By obtaining the preliminary development limit ranges for fire-driven permeability and crude oil viscosity through the combustion tube fire-driven permeability model experiment and the precise development limit ranges for fire-driven permeability and crude oil viscosity through the core thermal effect monitoring experiment, the method effectively correlates the combustion tube and core thermal effect monitoring results to derive the final development limits for fire-driven permeability and crude oil viscosity. This method is of great significance for guiding air injection development in oil fields.

[0078] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining fire flood permeability and crude oil viscosity development thresholds, applied to a system for determining fire flood permeability and crude oil viscosity development thresholds, the system comprising: The combustion tube fire-driven physical model experimental system and the core thermal effect monitoring experimental system are characterized by including the following steps: Step 1: Conduct fire-drive physical model experiments using a combustion tube fire-drive experimental system to obtain preliminary development limits for fire-drive permeability and crude oil viscosity. This includes the following steps: Step 101: Mix oil, water and sand thoroughly and fill them into the combustion tube. Each time, fill the tube with a set amount of equal mixture and compact it with a sand-pressing device, applying a set pressure and compaction time until the mixture is filled to the sealing section of the combustion tube. Step 102: Install the sealing flange, igniter, temperature monitoring probe and heater according to the combustion tube fire-driven physical model experimental system, and fill the annular space in the combustion tube and pressure sleeve with aluminum silicate to reduce heat loss during the reaction process. Step 103: Check the airtightness of the system. After the check is completed, measure the nitrogen permeability of the combustion tube using a soap film flow meter. After the measurement is completed, seal the real-time pressure chamber of the combustion tube. After sealing, conduct an ignition test. After the test is completed, inject nitrogen to extinguish the fire. The test is completed, and the preliminary development limit range of fire-driven permeability and crude oil viscosity is obtained. Step 2: Conduct multiple core thermal effect monitoring experiments using the core thermal effect monitoring experimental system to obtain the precise development limits for fire-driven permeability and crude oil viscosity. Specific steps include: Step 201: Insert the thermocouple into the injection end of the quartz reactor, inject quartz sand from the outlet end to the injection end, and inject silica gel particles into the quartz reactor, wherein the head of the thermocouple is located at the center of the silica gel particle block. Step 202: Obtain the core and saturate it with oil and water. Measure the core permeability using a soap film flow meter and place the measured core into a quartz reactor. Step 203: Fill the remaining space in the quartz reactor with quartz sand. After filling, place another thermocouple at the center of the quartz reactor to test the temperature of the core. Heat the quartz reactor with a ceramic heater and inject air into the injection end of the transparent quartz reactor to conduct experiments and obtain the precise development limits of fire-driven permeability and crude oil viscosity. Step 3: Correlate the preliminary development limits of fire-driven permeability and crude oil viscosity with the precise development limits of fire-driven permeability and crude oil viscosity to obtain the final development limits of fire-driven permeability and crude oil viscosity.

2. The method for determining the development limits of fire-driven permeability and crude oil viscosity according to claim 1, characterized in that, The filling length of the quartz sand injected from the outlet to the injection end is 5cm, and the filling length of the silica gel particles is 2.5cm.

3. The method for determining the development limits of fire-driven permeability and crude oil viscosity according to claim 1, characterized in that, The core sample has a diameter of 1.9 cm and a length of 10 cm.

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