CN116593522A - Device and method for measuring starting temperature of thick oil in porous medium - Google Patents
Device and method for measuring starting temperature of thick oil in porous medium Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 239000003921 oil Substances 0.000 claims abstract description 107
- 239000010779 crude oil Substances 0.000 claims abstract description 68
- 230000035699 permeability Effects 0.000 claims abstract description 47
- 238000004364 calculation method Methods 0.000 claims abstract description 26
- 238000002347 injection Methods 0.000 claims abstract description 20
- 239000007924 injection Substances 0.000 claims abstract description 20
- 238000006073 displacement reaction Methods 0.000 claims description 10
- 238000012417 linear regression Methods 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 8
- 239000000295 fuel oil Substances 0.000 claims description 8
- 229920006395 saturated elastomer Polymers 0.000 claims description 8
- 239000011435 rock Substances 0.000 claims description 6
- 230000006641 stabilisation Effects 0.000 claims description 3
- 238000011105 stabilization Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 8
- 238000011161 development Methods 0.000 abstract description 2
- 238000002474 experimental method Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 5
- 238000005086 pumping Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 230000000977 initiatory effect Effects 0.000 description 3
- 238000004891 communication Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 208000005156 Dehydration Diseases 0.000 description 1
- 238000010795 Steam Flooding Methods 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/02—Investigating or analyzing materials by the use of thermal means by investigating changes of state or changes of phase; by investigating sintering
- G01N25/12—Investigating or analyzing materials by the use of thermal means by investigating changes of state or changes of phase; by investigating sintering of critical point; of other phase change
Abstract
The invention belongs to the technical field of oil and gas field development, and particularly relates to a device and a method for measuring thick oil starting temperature in a porous medium, wherein the method for measuring thick oil starting temperature in the porous medium comprises the following steps: firstly, preparing a crude oil sample and a core sample; injecting a crude oil sample into the core sample to stabilize the pressure of the injection end; secondly, changing the experimental flow rate to obtain a relation curve of the flow rate and the pressure gradient, and calculating to obtain a core to-be-started pressure gradient value; then changing the experimental temperature to obtain the pressure gradient value to be started by the core at different temperatures, so as to obtain the starting temperature of the thick oil; finally, changing the permeability to obtain thick oil starting temperature under different permeability, and obtaining a calculation formula of thick oil starting temperature through linear fitting. By considering the influence of the permeability of the porous medium in the experimental process, the calculation formula for obtaining the thick oil starting temperature can be applied to reservoirs with different permeability, and the application range of the method for measuring the thick oil starting temperature in the porous medium is further improved.
Description
Technical Field
The invention belongs to the field of oil and gas field development technology, and particularly relates to a device and a method for measuring thick oil starting temperature in a porous medium.
Background
The world thick oil resources are very abundant, accounting for about 70% of the total global petroleum resources, and in general, crude oil with viscosity higher than 100mpa·s after degassing under the condition of oil layer can be called thick oil. Under the general reservoir conditions, the thick oil with the viscosity of thousands to tens of thousands of millipascal-seconds cannot flow, and the thick oil only starts to flow when the displacement pressure gradient is larger than the thick oil starting pressure gradient. The magnitude of the thick oil start-up pressure gradient is related to the permeability of the porous medium and the intrinsic viscosity of the fluid.
Most oilfield sites in the prior art rely on static means to test abnormal temperature points of thick oil to obtain the flow capacity of the thick oil in a porous medium, and generally obtain temperature points with mutation of relevant physical properties of the thick oil according to a viscosity-temperature curve or a rheological curve, for example, the viscosity dip of the thick oil or the yield stress becomes zero, so as to judge whether a thick oil reservoir reaches the exploitation condition of steam flooding. Aiming at the related technology, the method can not be applied to oil reservoirs with different permeability because the influence of the properties of the porous medium is ignored, and has the technical problems that the method can not be widely popularized and can only be applied in certain specific ranges.
Disclosure of Invention
The invention mainly aims to provide a device and a method for measuring the starting temperature of thick oil in a porous medium, so as to solve the technical problem that the prior art cannot be applied to reservoirs with different permeability, so that the application range is small.
In order to achieve the above object, the present invention provides a method for measuring a starting temperature of thick oil in a porous medium, comprising:
s1: preparing a crude oil sample and a core sample;
s2: performing constant temperature treatment on the core sample at the experimental temperature, and continuously injecting a crude oil sample into the core sample at the initial flow rate until the pressure of the injection end of the core sample is stable;
s3: continuously injecting a crude oil sample into the rock core sample with stable injection end pressure at the experimental flow rate, and obtaining a pressure value of the injection end pressure after secondary stabilization;
s4: repeatedly changing the experimental flow rate, repeating the step S3, and calculating to obtain a pressure gradient value to be started by the core;
s5: repeatedly changing the experimental temperature, repeating the steps S2 to S4, and obtaining the starting temperature of the thick oil according to the rock core to-be-started pressure gradient values at different experimental temperatures;
s6: and (3) changing the permeability of the core sample for a plurality of times, repeating the steps S2 to S5, and obtaining a calculation formula of the thick oil starting temperature according to the thick oil starting temperature under different permeability.
In an embodiment of the present invention, step S1 includes:
s11: dewatering crude oil by using a crude oil dewatering instrument;
s12: filtering the dehydrated crude oil by using a screen to obtain a crude oil sample;
s13: selecting a core model with known permeability, measuring the length, and injecting a crude oil sample into the core model at a constant speed until the crude oil sample is saturated;
s14: and standing the saturated core model for a first preset time to obtain a core sample.
In the embodiment of the invention, the temperature range of the filtering treatment is 75-80 ℃, and the first preset time period is not less than 24 hours.
In an embodiment of the present invention, step S2 includes:
s21: placing a core sample in an experimental temperature environment;
s22: when the core sample reaches the experimental temperature, carrying out constant temperature treatment for a second preset time period;
s23: injecting a crude oil sample into the core sample subjected to constant temperature treatment at an initial flow rate;
s24: and (3) standing for a third preset time period after the pressure of the injection end of the core sample is stable.
In an embodiment of the present invention, step S4 includes:
changing the experimental flow rate for multiple times to obtain corresponding different pressure values under different experimental flow rates;
calculating a plurality of pressure gradient values under different experimental flow rates according to the plurality of pressure values and the length of the core model;
drawing a first relation curve according to the experimental flow rate and the pressure gradient value and fitting a linear regression equation;
and calculating to obtain the intercept of the linear regression equation, namely the pressure gradient value of the core to be started.
In an embodiment of the present invention, step S5 includes:
and continuously changing the experimental temperature until the obtained core is started to have a pressure gradient value of 0, wherein the experimental temperature at the moment is the thick oil starting temperature.
In an embodiment of the present invention, step S6 includes:
respectively calculating 50 ℃ fluidity corresponding to the plurality of permeabilities, wherein the 50 ℃ fluidity is the ratio between the permeabilities and the viscosity of the crude oil sample at 50 ℃;
drawing a second relation curve of the inverse start temperature of the thick oil with different permeabilities and the logarithm of the fluidity at 50 ℃;
and fitting a calculation formula of the thick oil starting temperature according to the second relation curve.
In the embodiment of the invention, the calculation formula of the thick oil starting temperature is as follows:
wherein T is s The starting temperature of the thick oil is set at DEG C; k is permeability, mD; mu (mu) 50 The viscosity of the crude oil sample at 50 ℃ is mPa.s; a and b are both constants.
In the embodiment of the invention, the initial flow rate ranges from 0.001mL/min to 0.01mL/min, the experimental flow rate ranges from 0.05mL/min to 0.5mL/min, and the experimental temperature is not less than 30 ℃.
In an embodiment of the present invention, there is also provided a device for measuring a starting temperature of thick oil in a porous medium, which is applied to the method for measuring a starting temperature of thick oil in a porous medium as described above, the device for measuring a starting temperature of thick oil in a porous medium includes:
a piston for loading a crude oil sample;
the core holder is connected with the outlet end of the piston and is used for holding a core sample;
the displacement pump is connected with the inlet end of the piston and is used for pumping the crude oil sample into the core holder;
the incubator is used for adjusting the experimental temperature;
and the data acquisition equipment is used for measuring and acquiring the pressure value.
Through the technical scheme, the method for measuring the starting temperature of the thick oil in the porous medium has the following beneficial effects:
in the measurement process, firstly preparing a crude oil sample and a core sample which meet experimental conditions; continuously injecting a crude oil sample into the core sample at a low speed to stabilize the injection end pressure of the core sample; secondly, changing the experimental flow rate to obtain a relation curve of the flow rate and the pressure gradient value, and calculating to obtain a core to-be-started pressure gradient value; then changing the experimental temperature to obtain the pressure gradient value to be started by the core under different experimental temperatures, so as to obtain the starting temperature of the thick oil; and finally, changing the permeability of the core sample to obtain thick oil starting temperatures under different permeability, so as to obtain a calculation formula of the thick oil starting temperatures. The calculation formula of the thick oil starting temperature is obtained through experiments, and the influence of the porous medium is considered in the experimental process, so that the calculation formula of the thick oil starting temperature can be applied to oil reservoirs with different permeabilities, and the application range of the method for measuring the thick oil starting temperature in the porous medium is further improved.
Drawings
The accompanying drawings are included to provide an understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
FIG. 1 is a schematic flow chart of a method for measuring the start-up temperature of heavy oil in a porous medium according to an embodiment of the invention;
FIG. 2 is a schematic structural diagram of an apparatus for measuring the starting temperature of thick oil in a porous medium according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a first relationship curve of core model number 1 according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a first relationship curve of core model number 2 according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a first relationship curve of core model number 3 according to an embodiment of the present invention;
FIG. 6 is a graph showing the relationship between the pressure gradient value and the temperature of the core to be started according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a second relationship in an embodiment according to the invention.
Description of the reference numerals
| Reference numerals | Name of the name | Reference numerals | Name of the name |
| 1 | Piston | 3 | Core holder |
| 2 | Displacement pump | 4 | Data acquisition device |
Detailed Description
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the present invention.
The method according to the invention for measuring the start-up temperature of heavy oil in a porous medium is described below with reference to the accompanying drawings.
As shown in fig. 1, in an embodiment of the present invention, there is provided a method for measuring a starting temperature of thick oil in a porous medium, including:
s1: preparing a crude oil sample and a core sample;
s2: performing constant temperature treatment on the core sample at the experimental temperature, and continuously injecting a crude oil sample into the core sample at the initial flow rate until the pressure of the injection end of the core sample is stable;
s3: continuously injecting a crude oil sample into the rock core sample with stable injection end pressure at the experimental flow rate, and obtaining a pressure value of the injection end pressure after secondary stabilization;
s4: repeatedly changing the experimental flow rate, repeating the step S3, and calculating to obtain a pressure gradient value to be started by the core;
s5: repeatedly changing the experimental temperature, repeating the steps S2 to S4, and obtaining the starting temperature of the thick oil according to the rock core to-be-started pressure gradient values at different experimental temperatures;
s6: and (3) changing the permeability of the core sample for a plurality of times, repeating the steps S2 to S5, and obtaining a calculation formula of the thick oil starting temperature according to the thick oil starting temperature under different permeability.
In the deduction process of the calculation formula, firstly preparing a crude oil sample and a core sample which meet experimental conditions; continuously injecting a crude oil sample into the core sample at a low speed to stabilize the injection end pressure of the core sample; secondly, changing the experimental flow rate to obtain a relation curve of the flow rate and the pressure gradient value, and calculating to obtain a core to-be-started pressure gradient value; then changing the experimental temperature to obtain the pressure gradient value to be started by the core under different experimental temperatures, so as to obtain the starting temperature of the thick oil; and finally, changing the permeability of the core sample to obtain thick oil starting temperatures under different permeability, so as to obtain a calculation formula of the thick oil starting temperatures. The calculation formula of the thick oil starting temperature is obtained through experiments, and the influence of the porous medium is considered in the experimental process, so that the calculation formula of the thick oil starting temperature can be applied to oil reservoirs with different permeabilities, and the application range of the method for measuring the thick oil starting temperature in the porous medium is further improved. The reliability of the calculation method is improved by fully considering the influence of multiple factors such as temperature, pressure and the like in the calculation formula derivation process.
In an embodiment of the present invention, step S1 includes:
s11: dewatering crude oil by using a crude oil dewatering instrument;
s12: filtering the dehydrated crude oil by using a screen to obtain a crude oil sample;
s13: selecting a core model with known permeability, measuring the length, and injecting a crude oil sample into the core model at a constant speed until the crude oil sample is saturated;
s14: and standing the saturated core model for a first preset time to obtain a core sample.
Specifically, the crude oil is dehydrated in a constant temperature environment until the water content of the crude oil is lower than 0.3%, a stainless steel screen with the aperture of 0.045mm is selected for filtering treatment after the dehydration treatment is finished, and partial large particle impurities in the crude oil are removed through the filtering treatment, so that the influence of the impurities on the subsequent experimental process is reduced, the filtering treatment is required to be carried out in an environment with the temperature range of 75-80 ℃, and the optimal temperature is 80 ℃, so that the impurities are filtered more fully. Finally obtaining crude oil samples used for experiments.
Further, standing treatment of a first preset time is needed to be conducted on the saturated core model, wherein the first preset time is not less than 24 hours until the core model is sufficiently aged, and a core sample used for experiments is obtained. The crude oil sample and the core model are fully combined through standing treatment, so that the core sample can better simulate the shearing force of the crude oil sample in a real stratum, and the starting temperature of the thick oil in a porous medium can be obtained more accurately.
In an embodiment of the present invention, step S2 includes:
s21: placing a core sample in an experimental temperature environment;
s22: when the core sample reaches the experimental temperature, carrying out constant temperature treatment for a second preset time period;
s23: injecting a crude oil sample into the core sample subjected to constant temperature treatment at an initial flow rate;
s24: and (3) standing for a third preset time period after the pressure of the injection end of the core sample is stable.
Specifically, after the core sample is placed in the experimental temperature environment, the temperature of the core sample needs to be monitored from time to time, when the temperature of the core sample reaches the experimental temperature, the temperature cannot be changed immediately, the experimental temperature needs to be kept continuously for at least 2 hours, and then the core sample is placed in an experimental device for experiment. The third preset time period is not less than 8 hours, so that the core sample can be fully aged.
Further, the initial flow rate range is 0.001 mL/min-0.01 mL/min, the initial flow rate of 0.001mL/min is generally selected to slowly drive the liquid to the inlet end of the core sample, and the crude oil sample is slowly injected through the slower initial flow rate, so that the influence on the pressure stabilizing process due to the too fast flow rate is reduced, and the pressure stabilizing speed of the injection end of the core sample is further increased.
In an embodiment of the present invention, step S4 includes:
changing the experimental flow rate for multiple times to obtain corresponding different pressure values under different experimental flow rates;
calculating a plurality of pressure gradient values under different experimental flow rates according to the plurality of pressure values and the length of the core model;
drawing a first relation curve according to the experimental flow rate and the pressure gradient value and fitting a linear regression equation;
and calculating to obtain the intercept of the linear regression equation, namely the pressure gradient value of the core to be started.
Specifically, the experimental flow rate range is 0.05 mL/min-0.5 mL/min, the injection end pressure of the core sample is fluctuated each time when the injection end pressure of the core sample is stabilized again, a pressure value corresponding to the experimental flow rate at the moment is obtained, the pressure value is divided by the length of the core model to obtain a pressure gradient value, each group of corresponding experimental flow rate and pressure gradient value is finally drawn in a coordinate system taking the pressure gradient value as an abscissa and the experimental flow rate as an ordinate to form a first relation curve, a linear regression equation of the experimental flow rate and the pressure gradient value is obtained through fitting the first relation curve, and finally the intercept of the linear regression equation is calculated, so that the core to be started up pressure gradient value at the moment is obtained.
The core initiation-intended pressure gradient value means that when the pressure gradient value reaches the core initiation-intended pressure gradient value, the crude oil sample can flow in the core sample, namely, the crude oil sample can be successfully extracted.
In an embodiment of the present invention, step S5 includes:
and continuously changing the experimental temperature until the obtained core is started to have a pressure gradient value of 0, wherein the experimental temperature at the moment is the thick oil starting temperature.
Specifically, the corresponding core start-up pressure gradient value is finally obtained after each change of the experimental temperature, the change trend of the experimental temperature is from low to high, the experimental temperature is not less than 30 ℃, when the experimental temperature is increased to 0, the increase is stopped, and the experimental temperature at the moment is the thick oil start-up temperature corresponding to the core model with the permeability. The experimental temperature is changed, and the factor of the experimental temperature is added into a calculation formula of the thick oil starting temperature, so that the application range of the method for measuring the thick oil starting temperature in the porous medium is increased.
In an embodiment of the present invention, step S6 includes:
respectively calculating 50 ℃ fluidity corresponding to the plurality of permeabilities, wherein the 50 ℃ fluidity is the ratio between the permeabilities and the viscosity of the crude oil at 50 ℃;
drawing a second relation curve of the inverse start temperature of the thick oil with different permeabilities and the logarithm of the fluidity at 50 ℃;
and fitting a calculation formula of the thick oil starting temperature according to the second relation curve.
In the embodiment of the invention, the calculation formula of the thick oil starting temperature is as follows:
wherein T is s Is thick and thickOil start temperature, DEG C; k is permeability, mD; mu (mu) 50 The viscosity of the crude oil sample at 50 ℃ is mPa.s; a and b are both constants.
Specifically, the factor of permeability is added into a calculation formula of thick oil starting temperature through 50 ℃ fluidity, so that the calculation formula of thick oil starting temperature can be applied to oil reservoirs with different permeability, and the application range of a method for measuring thick oil starting temperature in a porous medium is further improved. Fluidity at 50 ℃ is the ratio between permeability and crude oil viscosity at 50 ℃, and the viscosity of a crude oil sample at 50 ℃ is measured by a viscometer.
Further, the invention calculates the temperature point of smooth flow of the thick oil with different viscosities in the core under different permeabilities by establishing the relation between the fluidity parameter and the thick oil starting temperature, comprehensively considers the thick oil flowable limit under the multi-factor effects of temperature, pressure and the like, and further improves the application range of the method for measuring the thick oil starting temperature in the porous medium. The flow capacity of the crude oil in reservoirs with different permeability can be accurately predicted by applying a calculation formula of the starting temperature of the thick oil in the oil reservoir exploitation of the crude oil, so that theoretical support and assistance are provided for determining the drainage radius and the driving temperature of the thick oil and optimizing the operation parameters and correcting the numerical simulation model of the thick oil on the oil reservoir site.
In an embodiment of the present invention, there is also provided a device for measuring a starting temperature of thick oil in a porous medium, which is applied to the method for measuring a starting temperature of thick oil in a porous medium as described above, the device for measuring a starting temperature of thick oil in a porous medium includes:
a piston 1 for loading a crude oil sample;
the core holder 3 is connected with the outlet end of the piston 1, and the core holder 3 is used for holding a core sample;
the displacement pump 2 is connected with the inlet end of the piston 1, and the displacement pump 2 is used for pumping a crude oil sample into the core holder 3;
the incubator is used for adjusting the experimental temperature;
and the data acquisition device 4 is used for measuring and acquiring the pressure value.
The following is a crude oil sample prepared from ordinary thick oil of Xinjiang oil field and a core sample prepared from three core models with different permeabilities, wherein parameters of the core models are shown in table 1, and the device and the method for measuring the starting temperature of thick oil in porous medium are described as a whole:
table 1 core model parameters for experiments
Firstly, selecting a No. 1 core model to be installed into a core holder 3, manufacturing a crude oil sample to be installed into a piston 1, and pumping the crude oil sample into the No. 1 core model by using a displacement pump 2 to be saturated;
secondly, placing the core holder 3 and the piston 1 into an incubator, setting the experimental temperature to be 30 ℃ to start constant temperature, and then slowly pumping the crude oil sample into the core sample by using the displacement pump 2 at an initial flow rate of 0.001mL/min, wherein the data acquisition equipment 4 continuously monitors the injection end pressure until the injection end pressure is stable;
as shown in fig. 3 to 5, the pressure gradient and the experimental flow rate are linearly fitted, the slope of the fitted straight line gradually increases as the temperature and the permeability increase, and the intercept of the abscissa axis gradually decreases, i.e., the pressure gradient to be started gradually decreases. When a certain temperature is reached, i.e. the temperature is higher than the starting temperature T of the thick oil s After that, the fitted straight line starts to pass through the origin, namely the pressure gradient of the core to be started is approximately zero, and the method is concretely as follows:
thirdly, using a displacement pump 2 to change the experimental flow rate to be 0.05mL/min, 0.1mL/min, 0.3mL/min and 0.5mL/min to obtain four data points with pressure values as horizontal coordinates and experimental flow rate as vertical coordinates, so as to fit a first relation curve corresponding to 30 ℃ and a corresponding linear regression equation, and further obtain a corresponding core quasi-start pressure gradient value at 30 ℃;
fourth, as shown in fig. 3, the experimental temperature is changed to 40 ℃,50 ℃, 70 ℃, 75 ℃ and 80 ℃ by using an incubator to obtain a first relation curve corresponding to each temperature and a core start-up pressure gradient value, and the corresponding core start-up pressure gradient value is obtained to be 0 when the temperature reaches 80 ℃, so that the thick oil start-up temperature corresponding to the model 1 is 80 ℃;
sixthly, as shown in fig. 4, the corresponding thick oil starting temperature is measured to be 70 ℃ by using a No. 2 core model;
seventh, as shown in fig. 5, the starting temperature of the corresponding thick oil is measured to be 65 ℃ by using a core model No. 3;
eighth, the obtained data are drawn in a coordinate system with temperature as an abscissa and a core initiation pressure gradient value as an ordinate, a relation curve of the core initiation pressure gradient value and the temperature is obtained, as shown in fig. 6, the initiation temperature of the common thick oil on the core with low permeability, medium permeability and high permeability is 80 ℃, 65 ℃ and 60 ℃ respectively;
ninth, as shown in fig. 7, introducing 50 ℃ fluidity parameters, obtaining effective starting pressure gradients at different permeabilities and different temperatures through fitting experimental results, only when the driving pressure gradient is larger than the effective flowing pressure gradient, flowing crude oil samples in the core, drawing a second relation curve of the inverse of the starting temperature of the thick oil and 50 ℃ fluidity logarithm to obtain a decrease of the starting temperature of the thick oil along with the increase of the permeabilities, and linearly fitting the inverse of the starting temperature and the 50 ℃ fluidity logarithm to obtain a calculation formula of the starting temperature of the thick oil with a correlation coefficient of 0.9978:
the above experimental procedure is an embodiment of the present invention, and the obtained calculation formula of the starting temperature of the thick oil corresponding to the crude oil used in the present invention does not represent the actual protection scope of the present invention, and only the specific operation steps of the measurement experiment are further described by the embodiment, so that the technical scheme can be better understood by those skilled in the art.
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (10)
1. A method for measuring the start-up temperature of a heavy oil in a porous medium, comprising:
s1: preparing a crude oil sample and a core sample;
s2: performing constant temperature treatment on the core sample at an experimental temperature, and continuously injecting the crude oil sample into the core sample at an initial flow rate until the injection end pressure of the core sample is stable;
s3: continuously re-injecting the crude oil sample into the core sample with stable injection end pressure at the experimental flow rate, and obtaining a pressure value of the injection end pressure after secondary stabilization;
s4: repeatedly changing the experimental flow rate, repeating the step S3, and calculating to obtain a pressure gradient value to be started by the core;
s5: repeatedly changing the experimental temperature, repeating the steps S2 to S4, and obtaining the thick oil starting temperature according to the rock core to-be-started pressure gradient values at different experimental temperatures;
s6: and (3) changing the permeability of the core sample for a plurality of times, repeating the steps S2 to S5, and obtaining a calculation formula of the thick oil starting temperature according to the thick oil starting temperature under different permeability.
2. The method for measuring the start-up temperature of heavy oil in a porous medium according to claim 1, wherein said step S1 comprises:
s11: dewatering crude oil by using a crude oil dewatering instrument;
s12: filtering the dehydrated crude oil by using a screen to obtain a crude oil sample;
s13: selecting a core model with known permeability, measuring the length, and injecting the crude oil sample into the core model at a constant speed until the crude oil sample is saturated;
s14: and standing the saturated core model for a first preset time to obtain the core sample.
3. The method for measuring the starting temperature of thick oil in a porous medium according to claim 2, wherein the temperature of the filtering treatment is in the range of 75 ℃ to 80 ℃, and the first preset time period is not less than 24 hours.
4. The method for measuring the start-up temperature of heavy oil in a porous medium according to claim 1, wherein said step S2 comprises:
s21: placing the core sample in the experimental temperature environment;
s22: when the core sample reaches the experimental temperature, performing constant temperature treatment for a second preset time period;
s23: injecting the crude oil sample into the core sample subjected to constant temperature treatment at the initial flow rate;
s24: and standing for a third preset time period after the pressure of the injection end of the core sample is stable.
5. The method for measuring the start-up temperature of heavy oil in a porous medium according to claim 1, wherein said step S4 comprises:
changing the experimental flow rate for multiple times to obtain corresponding different pressure values under different experimental flow rates;
calculating a plurality of pressure gradient values under different experimental flow rates according to the pressure values and the lengths of the core model;
drawing a first relation curve according to the experimental flow rate and the pressure gradient value and fitting a linear regression equation;
and calculating to obtain the intercept of the linear regression equation, namely the pressure gradient value to be started by the core.
6. The method for measuring the start-up temperature of heavy oil in a porous medium according to claim 1, wherein said step S5 comprises:
and continuously changing the experimental temperature until the obtained rock core to-be-started pressure gradient value is 0, and stopping the operation until the experimental temperature is the thick oil starting temperature.
7. The method for measuring the start-up temperature of heavy oil in a porous medium according to claim 1, wherein said step S6 comprises:
respectively calculating 50 ℃ fluidity corresponding to the plurality of permeabilities, wherein the 50 ℃ fluidity is the ratio between the permeabilities and the viscosity of the crude oil at 50 ℃;
drawing a second relation curve of the inverse start temperature of the thick oil with different permeabilities and the logarithm of the fluidity at 50 ℃;
and fitting a calculation formula of the thick oil starting temperature according to the second relation curve.
8. The method for measuring the starting temperature of thick oil in a porous medium according to claim 7, wherein the calculation formula of the starting temperature of thick oil is:
wherein T is s The starting temperature of the thick oil is set at DEG C; k is permeability, mD; mu (mu) 50 The viscosity of the crude oil sample at 50 ℃ is mPa.s; a and b are both constants.
9. The method for measuring the start-up temperature of thick oil in a porous medium according to any one of claims 1 to 8, wherein the initial flow rate is in the range of 0.001mL/min to 0.01mL/min, the experimental flow rate is in the range of 0.05mL/min to 0.5mL/min, and the experimental temperature is not less than 30 ℃.
10. An apparatus for measuring thick oil start-up temperature in a porous medium, characterized in that the method for measuring thick oil start-up temperature in a porous medium according to any one of claims 1 to 9 is employed, the apparatus for measuring thick oil start-up temperature in a porous medium comprising:
a piston for loading the crude oil sample;
the core holder is connected with the outlet end of the piston and is used for holding the core sample;
a displacement pump connected to an inlet end of the piston, the displacement pump being used to pump the crude oil sample into the core holder;
the incubator is used for adjusting the experimental temperature; and
and the data acquisition equipment is used for measuring and acquiring the pressure value of the core sample.
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