CN108508239A - A kind of analogy method directly measuring oil/water/rock three-phase intermolecular interaction - Google Patents

Abstract

The invention discloses a simulation method for directly measuring the interaction force between oil/water/rock three-phase molecules. The simulation method includes the following steps: modifying molecules containing characteristic functional groups of petroleum on the AFM probe for simulating the oil phase; using the aqueous solution and the substrate to simulate the water phase and the rock phase respectively, and the oil phase, the water phase and the rock phase are mixed The oil/water/rock three-phase system is obtained, and the direct measurement of the intermolecular interaction force of the oil/water/rock three-phase can be realized. Through the constructed "oil/water/rock three-phase system", the present invention can directly measure the intermolecular interactions between different characteristic functional groups and different substrates in different injection solutions, thus providing theoretical support for actual low-salinity water flooding work . In addition, by comparing the interaction force of different characteristic functional groups in the same environment, and the interaction force of the same functional group in different environments, the microscopic mechanism of the oil/water/rock three-phase interaction can be further analyzed and discussed.

Description

A Simulation Method for Directly Measuring the Intermolecular Interaction Forces of Oil/Water/Rock Three-Phase

technical field

The invention relates to a simulation method for directly measuring the interaction force between oil/water/rock three-phase molecules, and belongs to the technical field of atomic force microscope application.

Background technique

AFM technology obtains measurement information by scanning the surface of the sample with a fine needle tip. Because of its high-resolution observation capability (up to the atomic level) and high-sensitivity detection capability (up to the piccow level), it has been widely used in the fields of surface science, material science and life science since its invention. The development of the AFM force curve (the curve of the tip-sample interaction force with the tip-sample distance) method makes it possible to directly measure the intermolecular interaction force. It has extremely broad application prospects in scientific research, production, life and many other fields.

Studies have shown that the reservoir structure is very complex and heterogeneous, and a complex three-phase system of oil/water/rock will be formed after injection of low-salinity water, and the complex interaction between them will directly affect the actual recovery Rate. The essence of the so-called enhanced oil recovery is to realize the stripping of more crude oil from the wall surface of rock minerals. However, traditional experimental methods can only stay at the macroscopic level, and cannot directly detect the microscopic interactions at the oil/water/rock three-phase interface. Therefore, establishing a method that can directly detect the interaction between the oil/water/rock three-phase interface has become a necessary link for in-depth exploration of the microscopic oil displacement mechanism, and is also the key to maximizing the effectiveness of existing oil resources. where.

Contents of the invention

The purpose of the present invention is to provide a simulation method for directly measuring the interaction force between oil/water/rock three-phase molecules. Direct detection of interactions between oil/water/rock three-phase interfaces.

The simulation method for directly measuring the interaction force between oil/water/rock three-phase molecules provided by the present invention comprises the following steps:

Firstly, the three-phase system of oil/water/rock is constructed: the molecules containing the characteristic functional groups of petroleum are modified on the AFM probe to simulate the oil phase; the aqueous solution and the substrate are used to simulate the water phase and the rock phase respectively. The above-mentioned water phase and the above-mentioned rock phase are mixed to obtain an oil/water/rock three-phase system; and then the sub-liquid contact mode of the atomic force microscope is used for detection, which can realize the direct measurement of the intermolecular interaction force of the oil/water/rock three-phase .

In the above-mentioned simulation method, the AFM probe can be a gold-plated probe, and at this time, the molecule is modified on the AFM probe through a gold-sulfur bond; other plating tips can also be used according to the modification method;

In the above simulation method, the characteristic functional groups may be -CH ₃ , -COOH, -C ₆ H ₅ or -NH ₂ , etc., that is, the characteristic functional groups belonging to petroleum.

In the above simulation method, the aqueous solution contains different ions;

The ions may be sodium ions, chloride ions, magnesium ions, aluminum ions, sulfate ions, calcium ions and the like.

In the above simulation method, the ion concentration in the aqueous solution may be 1-1000 mM.

In the above simulation method, the substrate can be a typical mineral such as mica or quartz, which has an atomic-level surface flatness.

The present invention uses a special molecule with a mercapto group at one end and a characteristic functional group at the other end to form a monomolecular adsorption layer on the surface of the gold-plated probe through a gold-sulfur chemical bond to modify the functional group of the characteristic component in crude oil to the AFM probe to simulate the oil phase. . Using mica or quartz, a mineral with properties similar to rock cores, as the substrate, the rock facies is simulated. A liquid environment is provided by injection of an aqueous solution composed of different ions, simulating an aqueous phase. Thus, the direct measurement of intermolecular interactions in the oil/water/rock three-phase system can be realized. The invention belongs to the direct measurement of the interaction force between molecules by using atomic force microscope technology.

Through the constructed "oil/water/rock three-phase system", the present invention can directly measure the intermolecular interactions between different characteristic functional groups and different substrates in different injection solutions, thus providing theoretical support for actual low-salinity water flooding work . In addition, by comparing the interaction force of different characteristic functional groups in the same environment, and the interaction force of the same functional group in different environments, the microscopic mechanism of the oil/water/rock three-phase interaction can be further analyzed and discussed.

Description of drawings

Fig. 1 is a schematic diagram of AFM probes of different functionalized simulated oil phases constructed in Examples 1-4 of the present invention.

Fig. 2 is an AFM image of the natural mica substrate used in Example 1-2 of the present invention.

Fig. 3 is a force curve diagram of an oil/water/rock three-phase system using -CH ₃ as the oil phase in Example 1 of the present invention.

Fig. 4 is a force curve diagram of an oil/water/rock three-phase system using -COOH as the oil phase in Example 2 of the present invention.

Fig. 5 is a force curve diagram of an oil/water/rock three-phase system using -C ₆ H ₅ as the oil phase in Example 3 of the present invention.

Fig. 6 is a force curve diagram of an oil/water/rock three-phase system using -NH ₂ as the oil phase in Example 4 of the present invention.

Detailed ways

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.

Embodiment 1,

Preparation of aqueous solution for injection: Dissolve 5.80 g of sodium chloride in 1000 mL of water, stir to dissolve, and prepare a 1000 mM aqueous solution. Take 10mL, 1000mM sodium chloride solution and dilute to 100mL to obtain 100mM sodium chloride solution. Similarly, take 10mL and 100mM sodium chloride solution and dilute to 100mL to obtain a sodium chloride solution with a concentration of 10mM. Take 10 mL of 10 mM sodium chloride solution and dilute to 100 mL to obtain a sodium chloride solution with a concentration of 1 mM.

Modification of AFM probe: Soak the gold-plated probe of atomic force microscope (AFM) in the ethanol solution of crude oil characteristic functional group molecule with terminal group _-CH3 , soak for 24 hours, and the molecule passes through the gold-sulfur bond between the gold-plated probe and the molecule The formed monomolecular adsorption layer modified the functional groups of the characteristic components in crude oil onto the AFM probe to obtain a functionalized probe with -CH ₃ , as shown in Figure 1.

Preparation of lithofacies substrate: A natural mica sheet with atomic-level flatness was fixed on the patch as the substrate for simulating lithofacies in this example, and its AFM topography is shown in FIG. 2 .

As shown in Figure 3, it is the change of the force curve of the three-phase system with -CH ₃ as the simulated oil phase, NaCl aqueous solution as the water phase, and mica as the rock phase under different salt solution concentrations, that is, the directly measured oil/water/ The change curve of the interaction force between molecules in the rock three-phase system with distance, in which, the left figure is the approach curve, which reflects the change of the force during the approach process, and the right figure is the departure curve, which reflects the change of the adhesion force when leaving Changes.

Embodiment 2,

Preparation of aqueous solution for injection: Dissolve 5.80 g of sodium chloride in 1000 mL of water, stir to dissolve, and prepare a 1000 mM aqueous solution. Take 10mL, 1000mM sodium chloride solution and dilute to 100mL to obtain 100mM sodium chloride solution. Similarly, take 10mL and 100mM sodium chloride solution and dilute to 100mL to obtain a sodium chloride solution with a concentration of 10mM. Take 10 mL of 10 mM sodium chloride solution and dilute to 100 mL to obtain a sodium chloride solution with a concentration of 1 mM.

Modification of AFM probe: soak the gold-plated probe of atomic force microscope (AFM) in the ethanol solution of crude oil characteristic functional group molecule with -COOH terminal group, soak for 24 hours, and the molecule is formed through the gold-sulfur bond between the gold-plated probe and the molecule The monomolecular adsorption layer of the crude oil was modified to the functional group of the characteristic components in crude oil on the AFM probe, and the functionalized probe with -COOH was obtained, as shown in Figure 1.

Preparation of lithofacies substrates: A natural mica sheet with atomic-scale flatness was fixed to the patch as a substrate for the simulated lithofacies in this method.

As shown in Figure 4, it shows the change of the force curve of the three-phase system with -COOH as the simulated oil phase, NaCl aqueous solution as the water phase, and mica as the rock phase under different salt solution concentrations, that is, the directly measured oil/water/rock The change curve of the interaction force between molecules in the three-phase system with distance, in which the left figure is the approach curve, which reflects the change of the force during the approach process, and the right figure is the departure curve, which reflects the change of the adhesion force when leaving Happening.

Embodiment 3,

Preparation of aqueous solution for injection: Dissolve 5.80 g of sodium chloride in 1000 mL of water, stir to dissolve, and prepare a 1000 mM aqueous solution. Take 10mL, 1000mM sodium chloride solution and dilute to 100mL to obtain 100mM sodium chloride solution. Similarly, take 10mL and 100mM sodium chloride solution and dilute to 100mL to obtain a sodium chloride solution with a concentration of 10mM. Take 10 mL of 10 mM sodium chloride solution and dilute to 100 mL to obtain a sodium chloride solution with a concentration of 1 mM.

Modification of AFM probe: Soak the gold-plated probe of atomic force microscope (AFM) in the ethanol solution of crude oil characteristic functional group molecules with the end group -C ₆ H ₅ , soak for 24 hours, and the molecule passes through the gold-plated probe and the molecule between the gold- The monomolecular adsorption layer formed by sulfur bonds modified the functional groups of the characteristic components in crude oil onto the AFM probes to obtain functionalized probes with -C ₆ H ₅ , as shown in Figure 1.

Preparation of lithofacies substrates: A natural quartz sheet with atomic-scale flatness was fixed to the patch as a substrate for the simulated lithofacies in this method.

As shown in Fig. 5, it shows the change of the force curve of the three-phase system with -C ₆ H ₅ simulated oil phase, NaCl aqueous solution as the water phase, and mica as the rock phase under different salt solution concentrations, that is, the directly measured oil/ The change curve of the interaction force between molecules in the water/rock three-phase system with distance, in which, the left figure is the approach curve, which reflects the change of the force during the approach process, and the right figure is the departure curve, which reflects the adhesion when leaving. changes in force.

Embodiment 4,

Preparation of aqueous solution for injection: Dissolve 5.80 g of sodium chloride in 1000 mL of water, stir to dissolve, and prepare a 1000 mM aqueous solution. Take 10mL, 1000mM sodium chloride solution and dilute to 100mL to obtain 100mM sodium chloride solution. Similarly, take 10mL and 100mM sodium chloride solution and dilute to 100mL to obtain a sodium chloride solution with a concentration of 10mM. Take 10 mL of 10 mM sodium chloride solution and dilute to 100 mL to obtain a sodium chloride solution with a concentration of 1 mM.

Modification of AFM probe: Soak the gold-plated probe of atomic force microscope (AFM) in the ethanol solution of crude oil characteristic functional group molecule with _-NH2 terminal group, soak for 24 hours, and the molecule passes through the gold-sulfur bond between the gold-plated probe and the molecule The formed monomolecular adsorption layer modified the functional groups of the characteristic components in crude oil onto the AFM probe to obtain a functionalized probe with -NH ₂ , as shown in Figure 1.

Preparation of lithofacies substrates: A natural quartz sheet with atomic-scale flatness was fixed to the patch as a substrate for the simulated lithofacies in this method.

As shown in Figure 6, it is the change of the force curve of the three-phase system with _-NH2 simulated oil phase, NaCl aqueous solution as the water phase, and mica as the rock phase under different salt solution concentrations, that is, the directly measured oil/water/ The change curve of the interaction force between molecules in the rock three-phase system with distance, in which, the left figure is the approach curve, which reflects the change of the force during the approach process, and the right figure is the departure curve, which reflects the change of the adhesion force when leaving Changes.

Claims (6)

1. a kind of analogy method directly measuring oil/water/rock three-phase intermolecular interaction, includes the following steps：

By the molecular modification of the characteristic group containing oil on AFM probe, it to be used for model oil；Using aqueous solution and substrate It simulates water phase respectively and rock phase, the oil phase, the water phase and the rock mixes to obtain oil/water/rock three-phase system, The direct measurement of oil/water/rock three-phase intermolecular interaction can be realized.

2. analogy method according to claim 1, it is characterised in that：The AFM probe is plating Au probe, and the molecule is logical Gold-sulfide linkage modification is crossed on the AFM probe.

3. analogy method according to claim 1 or 2, it is characterised in that：The characteristic group is-CH₃、-COOH、- C₆H₅Or-NH₂。

4. analogy method according to any one of claim 1-3, it is characterised in that：Contain ion in the aqueous solution；

The ion is sodium ion, chlorion, magnesium ion, aluminium ion, sulfate ion or calcium ion.

5. analogy method according to claim 4, it is characterised in that：A concentration of 1~the 1000mM of aqueous solution intermediate ion.

6. analogy method according to any one of claims 1-5, it is characterised in that：The substrate is mica or quartz.