CN111896427A - Method for detecting mixed wettability of compact rock based on environmental scanning electron microscope - Google Patents
Method for detecting mixed wettability of compact rock based on environmental scanning electron microscope Download PDFInfo
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Abstract
The invention is suitable for the technical field of oil reservoir rock physical property measurement, and provides a method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope, which comprises the following steps: observing the section of the rock sample by using an environmental scanning electron microscope, and selecting a target area to be detected; cooling the sample, increasing the pressure of water vapor in the sample bin to enable condensate water to appear on the surface of the sample, and observing the condensation morphology characteristics of the target area to be detected; evaporating the condensed water on the surface of the rock sample, and observing the drying appearance characteristics of the target area to be detected; identifying the position of a pore of a target area to be detected according to the drying morphology characteristics of the target area to be detected; according to the condensation morphology characteristics of the pore position in the target area to be detected, the pore wall in the target area to be detected is divided into an oil-wet area and a water-wet area, and the oil-wet pore wall proportion and the water-wet pore wall proportion of the target area to be detected are obtained through calculation. The method can be used for rapidly, in-situ and quantitatively analyzing the mixed wettability of the rock.
Description
Technical Field
The invention belongs to the technical field of oil reservoir rock physical property measurement, and particularly relates to a method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope.
Background
Wettability is the tendency or degree of adhesion of two immiscible fluids to the same solid surface. The reservoir rock has the characteristic of mixed wetting, namely strong non-uniform wetting property exists in different positions, different minerals or pore canals with different sizes in the rock. The mixed wettability of the rock influences the flow and distribution of multiphase fluid in the rock, and has important significance on oil and gas migration and reservoir development research. If oleophilic pores and throats in the mixed wetting rock are increased, the power required for oil filling is reduced, and the oil is favorable for transporting and accumulating in a reservoir stratum. In the aspect of reservoir water flooding, rock mixed wettability has great influence on water drive efficiency and final oil recovery.
However, no effective method for quantitatively evaluating the mixed wettability of rock has been established at present. The main wettability measuring methods in the petroleum industry comprise a contact angle method, a USBM index method, an Amott index method and the like, and the methods can only test the integral and average wettability of a centimeter-scale rock sample and cannot quantitatively characterize the mixed wettability of the rock. Some researchers try to establish a quantitative characterization method for the mixed wetting degree of the rock according to the nuclear magnetic resonance response or the difference of the physical-chemical adsorption capacity of the oil (water) wetting surface in the rock, but the application effect is not good due to the complex mineral composition and distribution characteristics of the reservoir rock. The three-dimensional representation of the oil-water form in rock pores can be realized by utilizing a micron CT scanning technology, so that the contact angle of the pore size can be measured, and the mixing and wetting degree of the rock can be quantitatively evaluated. However, the method is limited by the precision of the micron CT technology, the oil-water-rock three-phase contact surface in the pore space of the dense rock cannot be accurately represented, the contact angle result has great uncertainty, the test flow is complex, the test price is high, and the method is not beneficial to industrial application.
Disclosure of Invention
The embodiment of the invention aims to provide a method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope, and aims to solve the problems in the background art.
The embodiment of the invention is realized in such a way that a method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope comprises the following steps:
preparing a rock sample with a new section;
observing the section of the rock sample by using an environmental scanning electron microscope, and selecting a target area to be detected;
placing a rock sample in a sample bin containing water vapor for cooling treatment, then increasing the pressure of the water vapor in the sample bin to a preset pressure value to enable condensate water to appear on the surface of the rock, and observing the condensation morphology characteristics of a target area to be detected by using an environmental scanning electron microscope;
volatilizing condensed water on the surface of the rock sample, and observing the drying morphology characteristics of the target area to be detected by using an environmental scanning electron microscope after the rock sample is dried;
identifying the position of a pore of a target area to be detected according to the drying morphology characteristics of the target area to be detected;
according to the condensation morphology characteristics of the pore position in the target area to be detected, the pore wall in the target area to be detected is divided into an oil-wet area and a water-wet area, and the oil-wet pore wall proportion and the water-wet pore wall proportion of the target area to be detected are obtained through calculation.
As a preferred solution to the embodiment of the invention, the thickness of the rock sample is not more than 3 mm.
As another preferred embodiment of the present invention, the cross-sectional area of the rock sample does not exceed 20mm2。
In another preferable scheme of the embodiment of the invention, in the step, the temperature of a cold stage for placing the rock sample is 3-7 ℃ during the cooling treatment.
As another preferable scheme of the embodiment of the present invention, in the step, the cooling method specifically includes:
and (3) placing the rock sample in a sample bin with the temperature of 3-7 ℃ and the water vapor pressure not higher than 5Torr for cooling treatment.
As another preferable scheme of the embodiment of the present invention, the method for determining the preset pressure value includes the following steps:
under the temperature condition of cooling treatment, placing the neutral wetting material in a sample bin with the water vapor pressure not higher than 5Torr for condensation experiment, and simultaneously observing whether condensed water appears on the surface of the neutral wetting material; in the condensation experiment process, gradually increasing the water vapor pressure in the sample bin at the frequency of 0.1-0.4 Torr each time until the surface of the neutral wetting material generates condensed water, stopping increasing the water vapor pressure, and recording the water vapor pressure at the moment as the preset pressure value;
wherein the neutral wetting material is polypropylene, and the water contact angle of the surface of the neutral wetting material is 90 degrees.
As another preferable scheme of the embodiment of the present invention, in the step, the method for dividing the target area to be measured into the oil-wet area and the water-wet area specifically includes:
superposing the condensation morphology characteristics of the target area to be detected with the pore positions of the target area to be detected, dividing the pore positions where the film-shaped and low dome-shaped condensed water appears into water wetting areas, and dividing the pore positions where the condensed water does not appear and the spherical condensed water appears into oil wetting areas.
As another preferable scheme of the embodiment of the present invention, in the step, the method for calculating the oil-wet pore wall ratio and the water-wet pore wall ratio of the target region to be measured specifically includes:
acquiring the pore position of a target area to be detected, the horizontal projection of an oil-wet area and the horizontal projection of a water-wet area, and respectively performing cleaning to obtain the number of pixels of pores on the surface of the rock, the number of pixels of the oil-wet area and the number of pixels of the water-wet area;
calculating to obtain the proportion of the oil-wet hole wall of the target area to be detected according to the ratio of the number of the pixels of the oil-wet area to the number of the pixels of the rock surface pore;
and calculating the proportion of the water-wetted hole wall of the target area to be measured according to the ratio of the number of the pixels of the water-wetted area to the number of the pixels of the rock surface pores.
According to the method for detecting the mixed wettability of the compact rock based on the environmental scanning electron microscope, the wettability of the rock surface in pore size is analyzed through controlling the condensation experimental conditions of the rock sample and observing the condensation characteristics of the sample surface, the oil-wet pore wall proportion and the water-wet pore wall proportion of the rock surface pore are counted, the method for quantitatively evaluating the mixed wettability of the rock is established, and the mixed wettability of the rock can be rapidly, in situ and quantitatively analyzed.
Drawings
Fig. 1 is a schematic flow chart of a method for detecting mixed wettability of dense rock based on an environmental scanning electron microscope according to an embodiment of the present invention.
FIG. 2 is a mosaic of dried topographical photographs of rock samples according to example 1 of the present invention.
FIG. 3 is a graph of the pore distribution identified from the dried sample profile in accordance with example 1 of the present invention.
FIG. 3A is a characteristic diagram of identifying the position of an aperture according to the depth of field of the surface of a sample according to example 1 of the present invention.
FIG. 3B is a characteristic diagram of pore location identification based on authigenic mineral development characteristics as is typical in example 1 of the present invention.
Fig. 4 is a mosaic of photographs of condensation characteristics of a rock sample section of example 1 of the present invention after the occurrence of condensed water.
FIG. 5 is a superimposed graph of the location of the pore space and the distribution of the condensation characteristics of the rock sample fracture in example 1 of the present invention.
Fig. 5A is a characteristic diagram typically identifying a water-wet area based on the distribution of the film-shaped condensed water in embodiment 1 of the present invention.
Fig. 5B is a characteristic diagram typically identifying an oil-wet area according to the distribution of uncondensed and globular condensed water in embodiment 1 of the present invention.
FIG. 6 is a graph showing the results of dividing a water-wet region and an oil-wet region according to the condensation characteristics of the pore wall surface in example 1 of the present invention.
Fig. 7 is a clear drawing of distribution diagrams of a target region to be measured, oil-wet pore walls, and water-wet pore walls in embodiment 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
As shown in fig. 1, this embodiment provides a method for detecting mixed wettability of dense rock based on an environmental scanning electron microscope, which includes the following steps:
s1, preparing a rock sample with a new section, enabling the thickness of the rock sample to be 3mm, enabling the section size to be about 4 x 4mm, and controlling the section and the bottom surface of the rock sample to be flat.
S2, placing the rock sample in a sample bin of an environmental scanning electron microscope, setting the environmental scanning electron microscope to be in an environmental scanning mode, setting the temperature of a cold stage to be 5.0 ℃, setting the water vapor pressure of the sample bin to be 5.0Torr, roughly observing the surface topography of the rock sample, and selecting the interested rock surface area as a target area to be detected.
S3, when the cooling time of the rock sample on a cold stage with the temperature of 5.0 ℃ exceeds 30min, the water vapor pressure of a sample bin is quickly increased to 8.1Torr, the time when the surface of the rock sample generates condensed water is observed, the condensed morphology characteristic of the target area to be measured is observed by using an environmental scanning electron microscope within a time period of 0-20 min after the rock sample generates the condensed water, and continuous photographing is carried out. In addition, under the temperature condition of 5.0 ℃, a neutral wetting material (polypropylene) with a surface water contact angle of 90 degrees is placed in a sample bin with the water vapor pressure of 5Torr for condensation experiment, and whether condensed water appears on the surface of the neutral wetting material is observed; in the condensation experiment process, the water vapor pressure in the sample bin is gradually increased at the frequency of 0.2-0.3 Torr each time until the surface of the neutral wetting material generates condensed water, and the water vapor pressure is stopped increasing, wherein the water vapor pressure at the moment is 8.1 Torr.
And S4, after the observation of the condensation morphological characteristics of the surface of the rock sample is finished, reducing the water vapor pressure of the sample bin to 5.0Torr to gradually volatilize condensed water on the surface of the rock sample, observing and continuously photographing the dry morphological characteristics of the sample section in the target area to be measured after the surface of the sample is dried, wherein the position of the photographed dry morphological characteristic picture corresponds to the position of the condensation morphological characteristic picture.
And S5, seamlessly splicing the dried morphological feature pictures shot in the step S4, as shown in FIG. 2, to obtain a large-scale spliced graph of the dried morphological features obtained in the examples.
S6, identifying the pore position of the target area to be detected on the rock surface according to the drying morphological characteristics of the target area to be detected, such as the depth of field of the sample surface, the roughness of the mineral surface, whether the foreign base is adhered to the mineral surface, the development condition of authigenic minerals and the like; FIG. 3 is a diagram of a pore distribution identified from the dried sample profile in an example embodiment; FIGS. 3A and 3B are enlarged partial views of a typical site, where the arrows in FIG. 3A indicate a large depth of field for a significant aperture; the arrows in fig. 3B indicate locations where authigenic minerals are abundantly developed, such as authigenic chlorite film, authigenic illite, and authigenic microcrystalline quartz, which are also the pore locations of the rock, although not characterized by large depth of field.
And S7, seamlessly splicing the condensation topographic features of the target area to be detected shot in the step S3, as shown in FIG. 4, which is a large-range splicing diagram of the condensation topographic features on the surface of the rock sample obtained in the embodiment.
And S8, superposing the pore positions identified in the step S6 and the extensive splicing map of the condensation topographic features on the surface of the rock sample obtained in the step S7, wherein the superposed map is the superposed map of the pore positions and the condensation feature distribution of the sample section obtained in the example, as shown in FIG. 5.
S9, comparing the appearance characteristics of the mineral surface at the pore position after the sample is dried and condensed water appears, analyzing the condensation characteristics at the pore position, namely whether condensed water appears and the morphological characteristics of the condensed water after the condensed water appears, and dividing the pore wall surface into an oil wetting area and a water wetting area according to the condensation characteristics, wherein the pore wall of the rock without the condensed water and with spherical condensed water appears is the oil wetting area, and the pore wall of the rock with film-shaped and low dome-shaped condensed water appears is the water wetting area; as shown in fig. 5A and 5B, fig. 5A and 5B are partial enlarged views of the exemplary location of fig. 5, where the locations of the pores indicated by arrows in fig. 5A are covered by film-like condensate, which is a distinct water-wetted pore wall; the positions of the pores indicated by the arrows in fig. 5B appear as uncondensed water or as spherically condensed water, with the apparent oil wetting the walls of the pores; in addition, as shown in fig. 6, fig. 6 is a graph showing the results of identifying the pore wall wettability at all pore positions.
And S10, clearly drawing the horizontal projection distribution of the observed target area to be measured, the pore position, the oil-wet area and the water-wet area, as shown in FIG. 7, which is the clearly drawn observation range, oil-wet pore wall and water-wet pore wall distribution diagram.
S11, counting the number of pixel points of the observed target area to be measured, the total pore position, the oil-wet area and the water-wet area, and calculating the rock face porosity (S)p) Oil-wetted pore wall ratio (Po) and water-wetted pore wall ratio (Pw), the calculation formula is as follows:
Rp＝Sp/St；
Po＝So/Sp；
Pw＝Sw/Sp；
wherein R ispIs the face porosity, SpThe number of pixel points of the total pore space of the target region to be measured on the rock surface, StFor total number of pixel points, P, of the observed target area to be measuredoThe proportion of the oil-wet area to the total pores, SoNumber of pixels, P, of oil-wet areawThe proportion of the water-wetted area to the total porosity, SwThe number of pixel points in the water-wetted area. The above calculation and statistics results are shown in table 1, the counted number of pixels occupied by rocks in the target region to be measured is 943055, the number of pixels occupied by total pores is 133222, the number of pixels occupied by oil-wet regions is 111660, and the number of pixels occupied by water-wet regions is 21562; the calculated rock face porosity was 14.1%, the oil-wetted hole wall ratio was 83.8%, and the water-wetted hole wall ratio was 16.2%.
TABLE 1
Example 2
The embodiment provides a method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope, which comprises the following steps:
s1, preparing a rock sample with a new section, enabling the thickness of the rock sample to be 2mm, enabling the section size to be about 4 x 5m, and controlling the section and the bottom surface of the rock sample to be flat.
S2, placing the rock sample in a sample bin of an environmental scanning electron microscope, setting the environmental scanning electron microscope to be in an environmental scanning mode, setting the temperature of a cold stage to be 3.0 ℃, setting the water vapor pressure of the sample bin to be 4.0Torr, roughly observing the surface topography of the rock sample, and selecting the interested rock surface area as a target area to be detected.
S3, when the cooling time of the rock sample on a cold stage with the temperature of 3.0 ℃ exceeds 20min, the water vapor pressure of the sample bin is quickly increased to a preset pressure value, the surface of the rock sample is observed when condensate water appears, the condensation morphology characteristics of the target area to be detected are observed by using an environmental scanning electron microscope within a time period of 0-20 min after the condensate water appears on the rock sample, and continuous photographing is carried out. The method for determining the pressure value preset in the step comprises the following steps:
under the temperature condition of 3.0 ℃, placing a neutral wetting material (polypropylene) with a surface water contact angle of 90 degrees in a sample bin with the water vapor pressure of 4Torr for condensation experiment, and simultaneously observing whether condensed water appears on the surface of the neutral wetting material; in the condensation experiment process, the water vapor pressure in the sample bin is gradually increased at the frequency of 0.1Torr each time until the surface of the neutral wetting material generates condensed water, and the water vapor pressure is stopped increasing, so that the water vapor pressure at the moment is the preset pressure value.
And S4, after the observation of the condensation morphological characteristics of the surface of the rock sample is finished, reducing the water vapor pressure of the sample bin to 4.0Torr to gradually volatilize condensed water on the surface of the rock sample, observing and continuously photographing the dry morphological characteristics of the sample section in the target area to be measured after the surface of the sample is dried, wherein the position of the photographed dry morphological characteristic picture corresponds to the position of the condensation morphological characteristic picture.
And S5, seamlessly splicing the dried morphological feature pictures shot in the step S4.
S6, identifying the pore position of the target area to be detected on the rock surface according to the drying morphological characteristics of the target area to be detected, such as the depth of field of the sample surface, the roughness of the mineral surface, whether the clay impurity base is adhered to the mineral surface, the development condition of authigenic minerals and the like.
And S7, seamlessly splicing the condensation morphology features of the target area to be detected shot in the step S3.
And S8, superposing the pore positions identified in the step S6 and the extensive splicing map of the condensation topographic features on the surface of the rock sample obtained in the step S7.
S9, comparing the appearance characteristics of the mineral surface at the pore position after the sample is dried and condensed water appears, analyzing the condensation characteristics at the pore position, namely whether condensed water appears and the morphological characteristics of the condensed water after the condensed water appears, and dividing the pore wall surface into an oil wetting area and a water wetting area according to the condensation characteristics, wherein the pore wall of the rock without the condensed water and with spherical condensed water appears is the oil wetting area, and the pore wall of the rock with film-shaped and low dome-shaped condensed water appears is the water wetting area.
S10, performing cleaning drawing on the horizontal projection distribution of the observed target area to be detected, the pore position, the oil-wet area and the water-wet area.
S11, counting the number of pixel points of the observed target area to be measured, the total pore position, the oil-wet area and the water-wet area, and calculating the rock face porosity (S)p) Oil-wet pore wall ratio (P)o) And water-wet pore wall ratio (P)w) The calculation formula is the same as that of the above embodiment 1.
Example 3
The embodiment provides a method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope, which comprises the following steps:
s1, preparing a rock sample with a new section, enabling the thickness of the rock sample to be 2.5mm, enabling the section size to be about 3 x 3m, and controlling the section and the bottom surface of the rock sample to be flat.
S2, placing the rock sample in a sample bin of an environmental scanning electron microscope, setting the environmental scanning electron microscope to be in an environmental scanning mode, setting the temperature of a cold stage to be 7.0 ℃, setting the water vapor pressure of the sample bin to be 5.0Torr, roughly observing the surface topography of the rock sample, and selecting the interested rock surface area as a target area to be measured.
S3, when the cooling time of the rock sample on a cooling table at the temperature of 7.0 ℃ reaches 40min, quickly raising the water vapor pressure of the sample bin to a preset pressure value, observing when condensate water appears on the surface of the rock sample, observing the condensation morphology characteristics of the target area to be detected by using an environmental scanning electron microscope within a time period of 0-20 min after the condensate water appears on the rock sample, and continuously photographing. The method for determining the pressure value preset in the step comprises the following steps:
under the temperature condition of 7.0 ℃, placing a neutral wetting material (polypropylene) with a surface water contact angle of 90 degrees in a sample bin with the water vapor pressure of 5Torr for condensation experiment, and simultaneously observing whether condensed water appears on the surface of the neutral wetting material; in the condensation experiment process, the water vapor pressure in the sample bin is gradually increased at the frequency of 0.4Torr each time until the surface of the neutral wetting material generates condensed water, and the water vapor pressure is stopped increasing, so that the water vapor pressure at the moment is the preset pressure value.
And S4, after the observation of the condensation morphological characteristics of the surface of the rock sample is finished, reducing the water vapor pressure of the sample bin to 5.00Torr to gradually volatilize condensed water on the surface of the rock sample, observing and continuously photographing the dry morphological characteristics of the sample section in the target area to be measured after the surface of the sample is dried, wherein the position of the photographed dry morphological characteristic picture corresponds to the position of the condensation morphological characteristic picture.
And S5, seamlessly splicing the dried morphological feature pictures shot in the step S4.
S6, identifying the pore position of the target area to be detected on the rock surface according to the drying morphological characteristics of the target area to be detected, such as the depth of field of the sample surface, the roughness of the mineral surface, whether the clay impurity base is adhered to the mineral surface, the development condition of authigenic minerals and the like.
And S7, seamlessly splicing the condensation morphology features of the target area to be detected shot in the step S3.
And S8, superposing the pore positions identified in the step S6 and the extensive splicing map of the condensation topographic features on the surface of the rock sample obtained in the step S7.
S9, comparing the appearance characteristics of the mineral surface at the pore position after the sample is dried and condensed water appears, analyzing the condensation characteristics at the pore position, namely whether condensed water appears and the morphological characteristics of the condensed water after the condensed water appears, and dividing the pore wall surface into an oil wetting area and a water wetting area according to the condensation characteristics, wherein the pore wall of the rock without the condensed water and with spherical condensed water appears is the oil wetting area, and the pore wall of the rock with film-shaped and low dome-shaped condensed water appears is the water wetting area.
S10, performing cleaning drawing on the horizontal projection distribution of the observed target area to be detected, the pore position, the oil-wet area and the water-wet area.
S11, counting the number of pixel points of the observed target area to be measured, the total pore position, the oil-wet area and the water-wet area, and calculating the rock face porosity (S)p) Oil-wet pore wall ratio (P)o) And water-wet pore wall ratio (P)w) The calculation formula is the same as that of the above embodiment 1.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A method for detecting the mixed wettability of dense rock based on an environmental scanning electron microscope is characterized by comprising the following steps:
preparing a rock sample with a new section;
observing the section of the rock sample by using an environmental scanning electron microscope, and selecting a target area to be detected;
placing a rock sample in a sample bin containing water vapor for cooling treatment, then increasing the pressure of the water vapor in the sample bin to a preset pressure value to enable condensate water to appear on the surface of the rock, and observing the condensation morphology characteristics of a target area to be detected by using an environmental scanning electron microscope;
volatilizing condensed water on the surface of the rock sample, and observing the drying morphology characteristics of the target area to be detected by using an environmental scanning electron microscope after the rock sample is dried;
identifying the position of a pore of a target area to be detected according to the drying morphology characteristics of the target area to be detected;
according to the condensation morphology characteristics of the pore position in the target area to be detected, the pore wall in the target area to be detected is divided into an oil-wet area and a water-wet area, and the oil-wet pore wall proportion and the water-wet pore wall proportion of the target area to be detected are obtained through calculation.
2. The method for detecting mixed wettability of the compact rock based on the environmental scanning electron microscope, according to claim 1, wherein the thickness of the rock sample is not more than 3 mm.
3. The method for detecting mixed wettability of compact rock based on the environmental scanning electron microscope as claimed in claim 1 or 2, wherein the cross-sectional area of the rock sample is not more than 20mm2。
4. The method for detecting the mixed wettability of the compact rock based on the environmental scanning electron microscope as claimed in claim 1, wherein in the step, the temperature of a cold stage for placing the rock sample is 3-7 ℃ during cooling treatment.
5. The method for detecting mixed wettability of the dense rock based on the environmental scanning electron microscope according to claim 4, wherein in the step, the cooling treatment method specifically comprises the following steps:
and (3) placing the rock sample in a sample bin with the temperature of 3-7 ℃ and the water vapor pressure not higher than 5Torr for cooling treatment.
6. The method for detecting mixed wettability of the compact rock based on the environmental scanning electron microscope as claimed in claim 1, wherein the method for determining the preset pressure value comprises the following steps:
under the temperature condition of cooling treatment, placing the neutral wetting material in a sample bin with the water vapor pressure not higher than 5Torr for condensation experiment, and simultaneously observing whether condensed water appears on the surface of the neutral wetting material; in the condensation experiment process, gradually increasing the water vapor pressure in the sample bin at the frequency of 0.1-0.4 Torr each time until the surface of the neutral wetting material generates condensed water, stopping increasing the water vapor pressure, and recording the water vapor pressure at the moment as the preset pressure value;
wherein the neutral wetting material is polypropylene, and the water contact angle of the surface of the neutral wetting material is 90 degrees.
7. The method for detecting the mixed wettability of the dense rock based on the environmental scanning electron microscope according to claim 1, wherein in the step, the method for dividing the target area to be detected into an oil-wet area and a water-wet area specifically comprises:
superposing the condensation morphology characteristics of the target area to be detected with the pore positions of the target area to be detected, dividing the pore positions where the film-shaped and low dome-shaped condensed water appears into water wetting areas, and dividing the pore positions where the condensed water does not appear and the spherical condensed water appears into oil wetting areas.
8. The method for detecting the mixed wettability of the dense rock based on the environmental scanning electron microscope according to claim 1, wherein in the step, the method for calculating the oil-wetted pore wall ratio and the water-wetted pore wall ratio of the target region to be detected specifically comprises:
acquiring horizontal projections of a pore, an oil-wet area and a water-wet area of a target area to be detected, and respectively performing cleaning to obtain the number of pixels of the pore, the number of pixels of the oil-wet area and the number of pixels of the water-wet area on the surface of the rock;
calculating to obtain the proportion of the oil-wet hole wall of the target area to be detected according to the ratio of the number of the pixels of the oil-wet area to the number of the pixels of the rock surface pore;
and calculating the proportion of the water-wetted hole wall of the target area to be measured according to the ratio of the number of the pixels of the water-wetted area to the number of the pixels of the rock surface pores.
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