Microscopic remaining oil exploitation method

Abstract

The invention relates to a microcosmic residual oil exploitation method which comprises the following steps: sampling and analyzing a natural rock core sample to obtain types and corresponding contents of different microcosmic residual oil of the natural rock core sample; calculating a first content of the microscopic remaining oil started by reducing the interfacial tension and a second content of the microscopic remaining oil started by improving the microscopic sweep according to the types and corresponding contents of different microscopic remaining oil, according to the first content and the second content, calculating a first proportion of microcosmic remaining oil started by reducing the interfacial tension and a second proportion of microcosmic remaining oil started by improving the microcosmic sweep; and determining a natural rock core displacement method according to the first proportion and the second proportion, and exploiting the microscopic remaining oil by using the natural rock core displacement method. According to the method, the microscopic remaining oil is divided from the starting difference of the microscopic remaining oil, and the method is scientific, reliable and beneficial to selection of subsequent chemical flooding.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method for exploiting microscopic residual oil. Background Art

[0002] As the water drive development of major domestic oil fields has entered the high water content stage, how to improve the recovery rate of tertiary oil recovery has become the main challenge facing various oil fields. The main means of improving oil recovery at home and abroad include: chemical drive, gas drive and thermal recovery. Domestic water drive development of oil reservoirs mainly uses chemical drive to improve oil recovery. Common chemical drives include: polymer drive, polymer-surfactant binary drive and ternary composite drive. There are many factors that affect the recovery rate of chemical drive, mainly including the concentration of alkali, the concentration of surfactant, the concentration of polymer, the mineralization of formation water, the physical properties of reservoirs and the viscosity of underground crude oil.

[0003] How to choose the right chemical flooding method is the key to improving the recovery rate of the target reservoir. The main reference factors include macro factors and micro factors. Common macro factors include reservoir permeability, underground crude oil viscosity and formation homogeneity, and common micro factors include the type of residual oil in water flooding, pore structure and wettability.

[0004] In recent years, with the rapid progress and maturity of micro-technology, micro-factors have played an increasingly critical role in the selection of chemical flooding for target reservoirs. First, different types of micro-residual oil have a clear guiding role in the selection of chemical flooding: micro-residual oil in close contact with rock particles requires the ability of chemical flooding to reduce oil-water interfacial tension; a large amount of micro-residual oil is distributed in non-mainstream pores, which requires the ability to improve the mobility control of chemical flooding. Secondly, different pore structures also affect the selection of chemical flooding for target reservoirs.

[0005] The common classification of microscopic residual oil is based on the morphology of the microscopic residual oil. The morphology classification is simply based on appearance judgment, without any scientific reference to the formation and startup of residual oil, which is not conducive to the research of microscopic residual oil and the selection of chemical drive. Summary of the invention

[0006] The object of the present invention is to provide a method for recovering microscopic residual oil to improve the above-mentioned problems.

[0007] The present invention provides a method for recovering microscopic residual oil, comprising:

[0008] Sampling and analyzing natural core samples to obtain different types and corresponding contents of microscopic residual oil in natural core samples;

[0009] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content;

[0010] The natural core displacement method is determined according to the first proportion and the second proportion, and the microscopic remaining oil is exploited using the natural core displacement method.

[0011] Optionally, the types of microscopic residual oil include film-like residual oil on the pore surface, particle-adsorbed residual oil, inter-particle-adsorbed residual oil, corner-like residual oil and cluster-like residual oil.

[0012] Optionally, the microscopic residual oil activated by reducing the interfacial tension includes film-like residual oil on the pore surface, particle-adsorbed residual oil and inter-particle-adsorbed residual oil.

[0013] Optionally, the microscopic residual oil started by improving the microscopic contagion includes corner-shaped residual oil and cluster-shaped residual oil.

[0014] Optionally, determining a natural core displacement method according to the first proportion and the second proportion includes:

[0015] A binary composite oil-displacing agent is used for oil displacement, wherein when the first proportion is greater than the second proportion, the polymer content in the binary composite oil-displacing agent is less than the surfactant content; when the second proportion is greater than the first proportion, the polymer content in the binary composite oil-displacing agent is greater than the surfactant content.

[0016] Optionally, in the binary composite oil-displacing agent, the polymer content is 1-5 g / L.

[0017] Optionally, in the binary composite oil-displacing agent, the surfactant content is 0-5 g / L.

[0018] The beneficial effects of the present invention are:

[0019] 1. The existing classification of microscopic residual oil is based on the form of microscopic residual oil, and the classification has no practical guiding significance for the selection and formulation adjustment of subsequent chemical flooding. Aiming at the problems existing in the current microscopic residual oil classification method, the present invention provides a new microscopic residual oil classification method, which is classified according to the startup law of residual oil. Some residual oil needs to reduce interfacial tension and improve oil washing ability to start, and some residual oil needs to improve microscopic sweep ability to start; the method starts from the startup difference of microscopic residual oil and divides the microscopic residual oil. The method is scientific and reliable, and is conducive to the selection of subsequent chemical flooding.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by implementing the embodiments of the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a schematic diagram of the film-like residual oil on the pore surface;

[0023] Figure 2 This is a schematic diagram of residual oil in the form of particle adsorption;

[0024] Figure 3 This is a schematic diagram of corner-shaped residual oil;

[0025] Figure 4 This is a schematic diagram of clustered residual oil;

[0026] Figure 5 Schematic diagram of residual oil adsorbed between particles. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] The present invention provides a method for recovering microscopic residual oil, comprising:

[0029] Sampling and analyzing natural core samples to obtain different types and corresponding contents of microscopic residual oil in natural core samples;

[0030] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content;

[0031] The natural core displacement method is determined according to the first proportion and the second proportion, and the microscopic remaining oil is exploited using the natural core displacement method.

[0032] Furthermore, the types of microscopic residual oil include film-like residual oil on the pore surface, particle adsorption-like residual oil, inter-particle adsorption-like residual oil, corner-like residual oil and cluster-like residual oil.

[0033] (1) Particle-adsorbed residual oil refers to a type of residual oil in which oil droplets are adsorbed on the surface of rock particles. The colloid and asphaltene of the oil droplets are easily adsorbed on the surface of charged rock particles. During water flooding, due to the large interfacial tension between the displacing phase and the displaced phase, water flooding is difficult to start; (2) Pore surface film-like residual oil is a layer of oil film on the surface of rock particles, and its formation mechanism is similar to that of particle-adsorbed residual oil; (3) Clustered residual oil refers to a type of residual oil in which oil droplets are dispersed in porous media and appear in clusters or blocks. There are often smaller porous media around the water flow channel after water flooding. These places are restricted by microscopic sweep effects, forming a type of locally enriched residual oil. (4) Corner-shaped residual oil has a relatively small content in porous media and is generally found in complex porous media or closed pore throats. This type of residual oil is not easy to start. This type of residual oil remains due to the influence of pore structure and insufficient sweep; (5) Intergranular adsorbed residual oil is mainly distributed between rock particles or in places where clay minerals are enriched. It is a type of microscopic residual oil that is difficult to start;

[0034] Furthermore, the microscopic residual oil activated by reducing the interfacial tension includes the film-like residual oil on the pore surface, the particle-adsorbed residual oil and the inter-particle-adsorbed residual oil.

[0035] Furthermore, the microscopic residual oil activated by improving the microscopic spread includes corner-shaped residual oil and cluster-shaped residual oil.

[0036] Further, a natural core displacement method is determined according to the first proportion and the second proportion, including:

[0037] A binary composite oil-displacing agent is used for oil displacement, wherein when the first proportion is greater than the second proportion, the polymer content in the binary composite oil-displacing agent is less than the surfactant content; when the second proportion is greater than the first proportion, the polymer content in the binary composite oil-displacing agent is greater than the surfactant content.

[0038] The binary composite oil displacement agent is composed of polymer, surfactant and water.

[0039] Furthermore, in the binary composite oil-displacing agent, the polymer content is 1-5 g / L, for example, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, etc.

[0040] Furthermore, in the binary composite oil displacement agent, the surfactant content is 0-5 g / L, for example, it can be 0 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, etc.

[0041] The present invention has been tested for many times, and some test results are now cited as references to further describe the invention in detail, and the following is a detailed description in conjunction with specific embodiments.

[0042] Example 1

[0043] A method for recovering microscopic residual oil, comprising:

[0044] The natural core samples were sampled and analyzed to obtain the types and corresponding contents of different microscopic residual oils in the natural core samples; the types of microscopic residual oil include film-like residual oil on the pore surface, residual oil adsorbed on particles, residual oil adsorbed between particles, residual oil in corners and residual oil in clusters;

[0045] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; wherein the microscopic residual oil activated by reducing the interfacial tension includes pore surface film-like residual oil, particle adsorption-like residual oil and inter-particle adsorption-like residual oil, and the microscopic residual oil activated by increasing the microscopic sweep includes corner-like residual oil and cluster-like residual oil;

[0046] A binary composite oil-displacing agent is used for oil displacement, wherein the first proportion is greater than the second proportion, and the polymer content in the binary composite oil-displacing agent is less than the surfactant content. The polymer content in the binary composite oil-displacing agent is 2 g / L, and the surfactant content is 3 g / L.

[0047] Example 2

[0048] A method for recovering microscopic residual oil, comprising:

[0049] The natural core samples were sampled and analyzed to obtain the types and corresponding contents of different microscopic residual oils in the natural core samples; the types of microscopic residual oil include film-like residual oil on the pore surface, residual oil adsorbed on particles, residual oil adsorbed between particles, residual oil in corners and residual oil in clusters;

[0050] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; wherein the microscopic residual oil activated by reducing the interfacial tension includes pore surface film-like residual oil, particle adsorption-like residual oil and inter-particle adsorption-like residual oil, and the microscopic residual oil activated by increasing the microscopic sweep includes corner-like residual oil and cluster-like residual oil;

[0051] A binary composite oil-displacing agent is used for oil displacement, wherein the first proportion is greater than the second proportion, and the polymer content in the binary composite oil-displacing agent is less than the surfactant content. The polymer content in the binary composite oil-displacing agent is 1 g / L, and the surfactant content is 3 g / L.

[0052] Example 3

[0053] A method for recovering microscopic residual oil, comprising:

[0054] The natural core samples were sampled and analyzed to obtain the types and corresponding contents of different microscopic residual oils in the natural core samples; the types of microscopic residual oil include film-like residual oil on the pore surface, residual oil adsorbed on particles, residual oil adsorbed between particles, residual oil in corners and residual oil in clusters;

[0055] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; wherein the microscopic residual oil activated by reducing the interfacial tension includes pore surface film-like residual oil, particle adsorption-like residual oil and inter-particle adsorption-like residual oil, and the microscopic residual oil activated by increasing the microscopic sweep includes corner-like residual oil and cluster-like residual oil;

[0056] A binary composite oil-displacing agent is used for oil displacement, wherein the first proportion is greater than the second proportion, and the polymer content in the binary composite oil-displacing agent is less than the surfactant content. The polymer content in the binary composite oil-displacing agent is 3 g / L, and the surfactant content is 5 g / L.

[0057] Example 4

[0058] A method for recovering microscopic residual oil, comprising:

[0059] The natural core samples were sampled and analyzed to obtain the types and corresponding contents of different microscopic residual oils in the natural core samples; the types of microscopic residual oil include film-like residual oil on the pore surface, residual oil adsorbed on particles, residual oil adsorbed between particles, residual oil in corners and residual oil in clusters;

[0060] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; wherein the microscopic residual oil activated by reducing the interfacial tension includes pore surface film-like residual oil, particle adsorption-like residual oil and inter-particle adsorption-like residual oil, and the microscopic residual oil activated by increasing the microscopic sweep includes corner-like residual oil and cluster-like residual oil;

[0061] A binary composite oil-displacing agent is used for oil displacement, wherein the second proportion is greater than the first proportion, the polymer content in the binary composite oil-displacing agent is greater than the surfactant content, the polymer content in the binary composite oil-displacing agent is 3g / L, and the surfactant content is 1g / L.

[0062] Example 5

[0063] A method for recovering microscopic residual oil, comprising:

[0064] The natural core samples were sampled and analyzed to obtain the types and corresponding contents of different microscopic residual oils in the natural core samples; the types of microscopic residual oil include film-like residual oil on the pore surface, residual oil adsorbed on particles, residual oil adsorbed between particles, residual oil in corners and residual oil in clusters;

[0065] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; wherein the microscopic residual oil activated by reducing the interfacial tension includes pore surface film-like residual oil, particle adsorption-like residual oil and inter-particle adsorption-like residual oil, and the microscopic residual oil activated by increasing the microscopic sweep includes corner-like residual oil and cluster-like residual oil;

[0066] A binary composite oil-displacing agent is used for oil displacement, wherein the second proportion is greater than the first proportion, the polymer content in the binary composite oil-displacing agent is greater than the surfactant content, the polymer content in the binary composite oil-displacing agent is 5 g / L, and the surfactant content is 3 g / L.

[0067] Example 6

[0068] A method for recovering microscopic residual oil, comprising:

[0069] The natural core samples were sampled and analyzed to obtain the types and corresponding contents of different microscopic residual oils in the natural core samples; the types of microscopic residual oil include film-like residual oil on the pore surface, residual oil adsorbed on particles, residual oil adsorbed between particles, residual oil in corners and residual oil in clusters;

[0070] According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; wherein the microscopic residual oil activated by reducing the interfacial tension includes pore surface film-like residual oil, particle adsorption-like residual oil and inter-particle adsorption-like residual oil, and the microscopic residual oil activated by increasing the microscopic sweep includes corner-like residual oil and cluster-like residual oil;

[0071] A binary composite oil-displacing agent is used for oil displacement, wherein the second proportion is greater than the first proportion, the polymer content in the binary composite oil-displacing agent is greater than the surfactant content, the polymer content in the binary composite oil-displacing agent is 4 g / L, and the surfactant content is 3 g / L.

[0072] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for recovering microscopic residual oil, characterized in that: include: Sampling and analyzing natural core samples to obtain different types and corresponding contents of microscopic residual oil in natural core samples; According to the types and corresponding contents of different microscopic residual oils, a first content of the microscopic residual oil activated by reducing the interfacial tension and a second content of the microscopic residual oil activated by increasing the microscopic sweep are calculated, and a first proportion of the microscopic residual oil activated by reducing the interfacial tension and a second proportion of the microscopic residual oil activated by increasing the microscopic sweep are calculated according to the first content and the second content; The natural core displacement method is determined based on the first proportion and the second proportion, and the microscopic remaining oil is exploited using the natural core displacement method.

2. The method for recovering microscopic residual oil according to claim 1, characterized in that: The types of microscopic residual oil include film-like residual oil on the pore surface, particle adsorption-like residual oil, inter-particle adsorption-like residual oil, corner-like residual oil and cluster-like residual oil.

3. The method for recovering microscopic residual oil according to claim 1, characterized in that: The microscopic residual oil activated by reducing the interfacial tension includes film-like residual oil on the pore surface, particle-adsorbed residual oil and inter-particle-adsorbed residual oil.

4. The method for recovering microscopic residual oil according to claim 1, characterized in that: The microscopic residual oil started by improving the microscopic contagion includes corner residual oil and cluster residual oil.

5. The method for recovering microscopic residual oil according to claim 1, characterized in that: The natural core displacement method is determined based on the first proportion and the second proportion, including: A binary composite oil-displacing agent is used for oil displacement, wherein when the first proportion is greater than the second proportion, the polymer content in the binary composite oil-displacing agent is less than the surfactant content; when the second proportion is greater than the first proportion, the polymer content in the binary composite oil-displacing agent is greater than the surfactant content.

6. The method for recovering microscopic residual oil according to claim 5, characterized in that: In the binary composite oil displacement agent, the polymer content is 1-5 g / L.

7. The method for recovering microscopic residual oil according to claim 5, characterized in that: In the binary composite oil displacement agent, the surfactant content is 0-5g / L.

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