阅读说明：本技术 一种测量凝胶颗粒原位力学性质的方法 (method for measuring in-situ mechanical properties of gel particles ) 是由 季岩峰 祝仰文 王其伟 曹绪龙 窦立霞 赵方剑 徐辉 庞雪君 何冬月 董雯 于 2019-07-22 设计创作，主要内容包括：本发明属于油水井调剖堵水领域,具体涉及一种测量凝胶颗粒原位力学性质的方法。所述方法包括以下步骤：(1)凝胶颗粒预处理；(2)利用纳米压痕仪对步骤(1)预处理后的凝胶颗粒进行原位力学性能测试；(3)数据处理与分析。本发明所述方法可直接、快速、准确地测量凝胶颗粒的弹性模量、接触刚度、塑性参数等原位力学性质。本发明方法适用对象广泛,人工凝胶颗粒、生物凝胶颗粒均可采用本发明方法进行测定。(The invention belongs to the field of profile control and water shutoff of oil-water wells, and particularly relates to a method for measuring in-situ mechanical properties of gel particles. The method comprises the following steps: (1) pretreating gel particles; (2) carrying out in-situ mechanical property test on the gel particles pretreated in the step (1) by using a nano-indenter; (3) and (4) processing and analyzing data. The method can directly, quickly and accurately measure the elastic modulus, the contact rigidity, the plasticity parameters and other in-situ mechanical properties of the gel particles. The method has wide application objects, and the artificial gel particles and the biological gel particles can be measured by the method.)

1. a method for measuring in-situ mechanical properties of gel particles, comprising the steps of:

(1) Pretreating gel particles;

(2) Carrying out in-situ mechanical property test on the gel particles pretreated in the step (1) by using a nano-indenter;

(3) And (4) processing and analyzing data.

2. the method according to claim 1, wherein the gel particles are any one of artificial gel particles and biogel particles.

3. The method of claim 1, wherein the gel particle pre-treatment comprises: preparing a dispersion medium, preparing a gel particle dispersion system, separating gel particles and fixing the gel particles;

The dispersion medium is simulated formation water and comprises the following components in percentage by weight: 69.6ppm of sodium sulfate, 6191ppm of sodium chloride, 241.4ppm of anhydrous calcium chloride, 351.4ppm of magnesium chloride hexahydrate and the balance of deionized water.

4. A method according to claim 3, wherein the gel particle dispersion is formulated by: adding a certain amount of dispersion medium into a container, stirring the dispersion medium, uniformly and slowly adding a certain amount of gel particles to avoid agglomeration of the gel particles, and continuously stirring for a period of time to fully swell the gel particles to obtain a gel particle dispersion system.

5. A method according to claim 3, wherein the separation of the gel particles is by filtering the gel particles out of the dispersion with a filter paper or sieve.

6. The method of claim 3, wherein the fixing of the gel particles is performed by placing the gel particle sample on a steel substrate having anti-slip grooves on the surface, and then fixing the steel substrate on a magnetic sample stage while ensuring the substrate is horizontal.

7. The method of claim 1, wherein the mechanical property test performed on the gel particles comprises an indentation test or a scratch test.

8. The method according to claim 1 or 7, characterized in that the gel particles are subjected to a nanoindentation test using a quasi-static indentation method.

9. The method according to claim 8, wherein the step of performing in-situ mechanical property test on the gel particles pretreated in the step (1) by using a nanoindenter comprises the following steps: the method comprises the steps of determining the spatial position of a sample by using an optical microscope, accurately determining the spatial position of a point to be measured of gel particles to be measured by using an SPM in-situ imaging technology, setting a load loading mode and parameters of the sample in an experiment, finally monitoring the displacement of a pressure head and the size of a load in the pressing-in process by a computer in real time through a control sensor, recording a force-displacement curve of the displacement along with the change of the load, and analyzing and calculating the curve to obtain the in-situ mechanical properties of the gel particles.

10. Method according to claim 9, characterized in that the load control mode is chosen with a maximum load of 100-120mN, a loading and unloading of 20-30s and a dwell time at maximum load of 5-20 s.

Technical Field

The invention belongs to the field of profile control and water shutoff of oil-water wells, and particularly relates to a method for measuring in-situ mechanical properties of gel particles.

Background

At present, most oil fields in China enter a high water content oil extraction stage, and due to the influence of hydrodynamic geological action for a long time, stratum heterogeneity is intensified, cracks develop, and serious water channeling and flooding phenomena are generated, so that an oil well is exposed to water prematurely.

The gel particle (microsphere) modifying and flooding agent is a water-absorbing volume-expanding material, has no oil suction, and has gel volume shrinkage in oil. The gel particles have good viscoelasticity after absorbing water, and when the pressure difference is large, the gel particles generate deformation under the action of water drive pressure to drive the residual oil in the pores to move to a production well, so that the oil displacement effect can be realized; when the pressure difference is small, the gel particles can be retained in the pores of the stratum to play a role in plugging high-permeability zones and large pores of the stratum.

the mechanical property of the gel particles directly influences the profile control and flooding effect, and the existing gel particle mechanical property measurement method mostly uses a rheometer flat plate test system to measure the dispersion solution of the gel particles. The inventors found that this method has the following problems: (1) the dispersion medium has a large influence on the measurement result, and the measurement value is related to the system concentration; (2) in a dispersed system, there is an interaction between the particles, interfering with the measurement; (3) the particle size distribution is uneven, and the particle shape is irregular, so that the stress between the two flat plate clamps is uneven; (4) the distance between the two plates (the clamping distance) has a large influence on the measurement result; (5) during measurement, the linear viscoelastic region needs to be determined through strain scanning, and the testing process is long in time consumption. Therefore, the measurements obtained by the above method do not reflect the in situ mechanical properties of the gel particles.

The Chinese invention patent (CN104849176A) provides a method for preparing gel microspheres viscoelasticity based on sheet-shaped body glue. The method comprises the following steps:

(1) Preparing sheet body glue:

a. Uniformly mixing a monomer, a cross-linking agent and an additive used for synthesizing the microspheres in an aqueous solution, adding an initiator, and uniformly mixing to obtain a mixed solution;

b. B, preparing a sheet body rubber sheet from the mixed solution obtained in the step a; preferably, the mixed solution obtained in the step a is injected into a mold with a flat inner cavity, and after the mold is completely filled with no bubbles, the mold is sealed, and the mixed solution in the mold is subjected to polymerization reaction to obtain the sheet body glue; wherein, the mould is the preparation device of the sheet body glue;

c. B, placing the sheet body rubber prepared in the step b into simulated formation water, and after water absorption and expansion, preparing a sheet body rubber sheet for viscoelasticity measurement;

(2) and (2) performing viscoelasticity measurement on the flaky body adhesive sheet obtained in the step (1) by adopting a flat plate system of a rheometer to obtain the viscous modulus and the elastic modulus of the flaky body adhesive sheet under different frequencies, wherein the viscous modulus and the elastic modulus of the flaky body adhesive sheet are the viscous modulus and the elastic modulus of the microspheres.

Therefore, the method is tested on the sheet-shaped sample prepared by a specific method, has limitations and cannot be used as a conventional performance evaluation method. In addition, the elasticity and the strength of the body gel are actually measured by the method, and after the body gel is crushed into the gel particles, the mechanical environment of the particles is greatly different from that of the body gel, so that the method cannot truly reflect the in-situ mechanical properties of the gel particles. At present, a method capable of rapidly and accurately measuring the in-situ mechanical properties of gel particles is lacked.

Disclosure of Invention

The invention mainly aims to provide a method for measuring the in-situ mechanical property of gel particles, which realizes the rapid and accurate measurement of the in-situ mechanical property of the gel particles.

To achieve the above object, the present invention provides a method for measuring in-situ mechanical properties of gel particles, the method comprising the steps of:

(1) Pretreating gel particles;

(2) Carrying out in-situ mechanical property test on the gel particles pretreated in the step (1) by using a nano-indenter;

(3) and (4) processing and analyzing data.

the nano-indenter can be one of a NanoTest Xtreme nano-indenter of MML company, a Haisingchu TI 980 TriboInducer nano-indenter of Bruk, an NHT2 nano-indenter of CSM company and an iNano nano-indenter.

The system of the nano-indenter mainly comprises a pressure head, a scanning control system and a sensing system. The pressure head model of the nano-indenter comprises a Vikers pressure head, a Berkovich pressure head, a Cube-corner pressure head, a Cone pressure head and a Sphere pressure head. The nanoindentor needs to be calibrated, and the content of instrument calibration mainly comprises pressure head area function calibration and instrument compliance calibration.

In the method of the present invention, preferably, the gel particles are any one of artificial gel particles and biogel particles.

In the method of the present invention, preferably, the gel particle pretreatment comprises: preparing a dispersion medium, preparing a gel particle dispersion system, separating gel particles and fixing the gel particles;

The dispersion medium is simulated formation water and comprises the following components in percentage by weight: 69.6ppm of sodium sulfate, 6191ppm of sodium chloride, 241.4ppm of anhydrous calcium chloride, 351.4ppm of magnesium chloride hexahydrate and the balance of deionized water.

In the method of the present invention, preferably, the gel particle dispersion is prepared by: adding a certain amount of dispersion medium into a container, stirring the dispersion medium, uniformly and slowly adding a certain amount of gel particles to avoid agglomeration of the gel particles, and continuously stirring for a period of time to fully swell the gel particles to obtain a gel particle dispersion system.

in the process of the present invention, the separation of the gel particles is preferably carried out by filtering the gel particles out of the dispersion with a filter paper or sieve.

In the method of the present invention, preferably, the fixing of the gel particles is to place the gel particle sample on a steel substrate with anti-slip grooves on the surface, and then fix the steel substrate on a magnetic sample stage, and ensure the substrate to be horizontal.

In the method of the present invention, preferably, the gel particles are immobilized while keeping a certain distance between the particles to ensure that the particles do not contact each other and avoid interference with the measurement result.

in the method of the present invention, preferably, the mechanical property test performed on the gel particles comprises an indentation test or a scratch test.

In the method of the present invention, the gel particles are preferably subjected to a nanoindentation test using a quasi-static indentation method.

In the method of the present invention, preferably, the nanoindentation test step includes: the method comprises the steps of determining the spatial position of a sample by using an optical microscope, accurately determining the spatial position of a point to be measured of gel particles to be measured by using an SPM in-situ imaging technology, setting a load loading mode and parameters of the sample in an experiment, finally monitoring the displacement of a pressure head and the size of a load in the pressing-in process by a computer in real time through a control sensor, recording a force-displacement curve of the displacement along with the change of the load, and analyzing and calculating the curve to obtain the in-situ mechanical properties of the gel particles.

In the method of the invention, preferably, the load control mode is selected, the maximum load is 100-120mN, the loading and unloading are 20-30s, and the load-holding time at the maximum load is 5-20 s.

the invention has the following beneficial effects:

The method can directly, quickly and accurately measure the elastic modulus, the contact rigidity, the plasticity parameters and other in-situ mechanical properties of the gel particles. The method has wide application objects, and the artificial gel particles and the biological gel particles can be measured by the method.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the invention and are not to limit the invention.

FIG. 1 is a schematic view of an indentation test, wherein h_maxfor maximum penetration depth, hf is the residual penetration depth.

FIG. 2 is a force-displacement graph of the displacement of gel particles as a function of load as described in example 1.

FIG. 3 is a force-displacement graph of the displacement of gel particles as a function of load as described in example 2.

FIG. 4 is a force-displacement graph of the displacement of gel particles as a function of load as described in example 3.

FIG. 5 is a force-displacement graph of the displacement of gel particles as a function of load as described in example 4.

In the force-displacement curve diagram of the displacement changing along with the load, the horizontal axis is the press-in depth h, and the unit is mum; the ordinate is the load F in mN.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.

in order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

The instruments, reagents, materials and the like used in the following examples are conventional instruments, reagents, materials and the like in the prior art and are commercially available in a normal manner unless otherwise specified. Unless otherwise specified, the experimental methods, detection methods, and the like described in the following examples are conventional experimental methods, detection methods, and the like in the prior art.