A stress-sensitive tight sandstone reservoir physical model material and a stress-sensitive tight sandstone reservoir physical model and a preparation method thereof

Abstract

The present invention belongs to the technical field of seismic physical models of oil and gas exploration geophysics, and discloses a stress-sensitive tight sandstone reservoir physical model material and a stress-sensitive tight sandstone reservoir physical model and a preparation method. The physical model material includes quartz sand, kaolin, polyurethane, a curing agent, and a diluent. The method includes the following steps: heating the polyurethane and the curing agent; pre-curing the inner surface of the physical model curing mold; uniformly mixing the quartz sand and the kaolin, adding polyurethane and a curing agent, as well as a diluent, and uniformly mixing to obtain a mixture; placing the mixture into a physical model curing mold, and pressing and curing the mixture to obtain the stress-sensitive tight sandstone reservoir physical model. The present invention realizes a physical simulation study of the change law of the ground stress-seismic response of the tight sandstone reservoir by using soft organic materials to cement quartz sand and kaolin.

Description

Technical Field

[0001] The present invention belongs to the technical field of seismic physical models of oil and gas exploration geophysics, and in particular, relates to a stress-sensitive tight sandstone reservoir physical model material and a stress-sensitive tight sandstone reservoir physical model and a preparation method thereof. Background Art

[0002] With the continuous deepening of exploration, unconventional tight sandstone reservoirs have become the focus and hotspot of oil and gas exploration, and the proportion of its oil and gas reserves in the newly discovered crude oil and natural gas geological reserves has increased year by year. It is generally believed that sandstone with a porosity of less than 12% and a permeability of less than 0.1mD is a tight sandstone reservoir. The exploration and development of tight sandstone reservoirs is closely related to geostress. By determining the magnitude and direction of geostress, the optimal solution for reservoir development design can be provided. Therefore, the study of the relationship between geostress and seismic response characteristics is of great significance to reservoir exploration and development. At present, there are many assumptions in the numerical simulation technology of geostress-seismic response. For example, the geostress simulation based on the thin plate model assumption assumes that the studied stratum is uniform, continuous, isotropic, and completely elastic, which is quite different from the actual situation of the actual stratum.

[0003] Compared with mathematical simulation methods, physical simulation methods can more realistically observe the propagation laws of sound waves or elastic waves in the model medium, thereby inferring the propagation characteristics of seismic waves in actual stratigraphic structures and geological bodies, and are more conducive to explaining the characteristics of seismic response caused by ground stress. In the process of earthquake physical simulation, in order to make the kinematic characteristics of the simulation results consistent with the kinematic characteristics of seismic waves in the actual geological structure geological body, it is necessary to make the size, velocity, density and other parameters of the physical model have a certain proportional relationship with the size, velocity, density and other parameters of the actual geological structure geological body, that is, the geometric similarity principle of earthquake physical simulation. At present, the scale factor used in earthquake physical models is usually 1:10000, that is, 1 mm of the physical model represents the actual geological body scale of 10 meters; and the velocity ratio is usually 1:1 or 1:2.

[0004] The material sources of the sandstone reservoir seismic physical model can be divided into two types, one is polymer material and the other is artificial sandstone. Commonly used polymer physical model materials include epoxy resin, silicone rubber, organic glass, paraffin, etc. By casting and machining the materials, a more accurate geometric structure can be obtained, but such materials do not have porosity and permeability characteristics and can only simulate sandstone reservoirs in terms of velocity and density. The existing artificial sandstone materials are made by using organic or inorganic glue to bond quartz sand, which can simulate conventional sandstone with high porosity and high permeability, but it is difficult to simulate the physical properties of dense sandstone. In addition, both existing sandstone reservoir physical model materials are not stress sensitive, that is, after applying simulated stress, it is difficult for their physical parameters to change significantly, and it is difficult to simulate the influence of stress on the actual formation physical parameters.

[0005] In view of the defects of the existing physical simulation technology, it is urgent to improve it and propose new technical solutions to obtain a physical model of tight sandstone reservoirs with stress sensitivity, thereby more clearly revealing the changing laws of geostress-seismic response. Summary of the invention

[0006] The purpose of the present invention is to address the deficiencies of the prior art and propose a stress-sensitive tight sandstone reservoir physical model material and a stress-sensitive tight sandstone reservoir physical model and a preparation method. The present invention uses soft organic materials to cement quartz sand and kaolin, and performs high-pressure pressing to obtain a stress-sensitive tight sandstone model, thereby realizing a physical simulation study of the change law of the tight sandstone reservoir's ground stress-seismic response.

[0007] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a stress-sensitive tight sandstone reservoir physical model material, which comprises, by weight, 450-550 parts of quartz sand, 200-500 parts of kaolin, 50-100 parts of polyurethane, 5-10 parts of curing agent, and 5-10 parts of diluent.

[0008] The second aspect of the present invention provides a method for preparing a stress-sensitive tight sandstone reservoir physical model using the stress-sensitive tight sandstone reservoir physical model material, the method comprising the following steps:

[0009] S1: Material pretreatment: heating the polyurethane and curing agent;

[0010] S2: Mold pretreatment: Perform curing pretreatment on the inner surface of the physical model curing mold;

[0011] S3: material preparation: uniformly mixing the quartz sand and the kaolin, adding the polyurethane treated in step S1 and the curing agent treated in step S1, and a diluent, and uniformly mixing to obtain a mixture;

[0012] S4: Sand plate pressing: placing the mixture into the physical model solidification mold processed in step S2, and pressing the mixture;

[0013] S5: Sand plate solidification: After the pressing treatment, solidification treatment is performed to obtain the stress-sensitive tight sandstone reservoir physical model.

[0014] A third aspect of the present invention provides a physical model of a stress-sensitive tight sandstone reservoir.

[0015] The technical solution of the present invention has the following beneficial effects:

[0016] (1) The present invention utilizes soft organic materials to cement quartz sand and kaolin, and performs high-pressure pressing to obtain a dense sandstone model material with a porosity of less than 12% and a permeability of less than 0.1 mD, and its physical properties can change significantly under simulated ground stress conditions.

[0017] (2) The stress-sensitive tight sandstone model prepared by the present invention can achieve a P-wave velocity variation range of 0-400 m / s under a horizontal stress difference of 2 MPa, and can realize physical simulation research on the variation law of tight sandstone reservoir stress-seismic response.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.

[0020] Figure 1 A flow chart of a method for preparing a stress-sensitive tight sandstone reservoir physical model provided by the present invention is shown. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0022] The first aspect of the present invention provides a stress-sensitive tight sandstone reservoir physical model material, which comprises, by weight, 450-550 parts of quartz sand, 200-500 parts of kaolin, 50-100 parts of polyurethane, 5-10 parts of curing agent, and 5-10 parts of diluent.

[0023] According to the present invention, preferably:

[0024] The curing agent is an amine curing agent with an amine value of less than 400 mgKOH / g, preferably a cashew nut oil-modified fatty amine;

[0025] The diluent is an ester plasticizer, preferably dibutyl phthalate.

[0026] According to the present invention, preferably, the particle size of the quartz sand is 100-600 mesh, preferably 200-400 mesh; the particle size of the kaolin is 1000-1400 mesh, preferably 1000-1200 mesh.

[0027] The second aspect of the present invention provides a method for preparing a stress-sensitive tight sandstone reservoir physical model using the stress-sensitive tight sandstone reservoir physical model material, the method comprising the following steps:

[0028] S1: Material pretreatment: heating the polyurethane and curing agent;

[0029] S2: Mold pretreatment: Perform curing pretreatment on the inner surface of the physical model curing mold;

[0030] S3: material preparation: uniformly mixing the quartz sand and the kaolin, adding the polyurethane treated in step S1 and the curing agent treated in step S1, and a diluent, and uniformly mixing to obtain a mixture;

[0031] S4: Sand plate pressing: placing the mixture into the physical model solidification mold processed in step S2, and pressing the mixture;

[0032] S5: Sand plate solidification: After the pressing treatment, solidification treatment is performed to obtain the stress-sensitive tight sandstone reservoir physical model.

[0033] In the present invention, the pressing treatment is followed by a curing treatment, and then the model is demoulded and taken out to complete the preparation of the stress-sensitive tight sandstone reservoir physical model.

[0034] According to the present invention, preferably, in step S1, the temperature of the heating treatment is 40-60°C, and the time of the heating treatment is 1-3 hours. As a preferred solution, the equipment for the heating treatment is an incubator.

[0035] According to the present invention, preferably, in step S2, the curing pretreatment step includes applying silicone rubber to the inner surface of the physical model curing mold, and after the silicone rubber is cured, the curing pretreatment is completed.

[0036] According to the present invention, preferably, in step S3, the curing agent and polyurethane treated in step S1 are uniformly mixed, and then the diluent is added and uniformly mixed, and then added to the material in which the quartz sand and the kaolin are uniformly mixed, and all the materials are fully kneaded by mixing and stirring to avoid the appearance of large particles, so as to obtain the mixture.

[0037] According to the present invention, preferably, in step S4, the pressing time is 8-15 minutes, and the pressing pressure is 8MPa-14MPa, more preferably 10MPa. As a preferred embodiment, the mixture is placed in a physical model curing mold treated in step S2, and the mixture is pressed at 8MPa-14MPa for 8-15 minutes by a press, and then the pressure is released.

[0038] According to the present invention, preferably, in step S5, the curing treatment time is 36-60 hours, and the curing treatment temperature is 35-45°C.

[0039] A third aspect of the present invention provides a physical model of a stress-sensitive tight sandstone reservoir.

[0040] The present invention is specifically described below by way of examples.

[0041] In the following embodiments:

[0042] The polyurethane is a two-component polyurethane potting glue PUY-205, purchased from Suzhou Ruigu Chemical Co., Ltd.

[0043] The curing agent is cashew nut oil modified fatty amine ZY-F50, whose amine value is 200-300 mgKOH / g, purchased from Xuzhou Zhongyan Chemical Co., Ltd.;

[0044] The diluent is dibutyl phthalate, purchased from Jinan Chengen Chemical Co., Ltd.

[0045] The quartz sand is Jingshi brand quartz sand, produced in Hebei, with an average particle size of 300 meshes;

[0046] The kaolin is Xingpai calcined kaolin, produced in Shanxi, with an average particle size of 1100 mesh;

[0047] The physical model curing mold has a size of 10 cm×10 cm×2 cm.

[0048] Example 1

[0049] The present embodiment provides a stress-sensitive tight sandstone reservoir physical model material. The physical model material includes, by weight, 500 parts of quartz sand, 500 parts of kaolin, 70 parts of polyurethane, 10 parts of curing agent, and 10 parts of diluent.

[0050] This embodiment provides a method for preparing a stress-sensitive tight sandstone reservoir physical model using the stress-sensitive tight sandstone reservoir physical model material, such as Figure 1 As shown, the method comprises the following steps:

[0051] S1: Material pretreatment: placing the polyurethane and curing agent in a 50° C. incubator for heating for 2 h;

[0052] S2: Mold pretreatment: Performing curing pretreatment on the inner surface of the physical model curing mold; the curing pretreatment step includes applying silicone rubber on the inner surface of the physical model curing mold, and the curing pretreatment is completed after the silicone rubber is cured.

[0053] S3: Material preparation: uniformly mix the curing agent treated in step S1 and the polyurethane treated in step S1, then add the diluent and mix them uniformly, then add them to the material uniformly mixed with the quartz sand and the kaolin, mix and stir all the materials thoroughly to avoid the appearance of large particles, and obtain the mixture.

[0054] S4: Sand plate pressing: placing the mixture into the physical model solidification mold processed in step S2, and performing a pressing process on the mixture, wherein the pressing process is specifically performed by using a press to press at 10 MPa for 10 minutes and then release the pressure;

[0055] S5: Sand plate solidification: After the pressing treatment, the sand plate is solidified, and then the sand plate is demoulded and taken out to complete the production of the stress-sensitive tight sandstone reservoir physical model, and the stress-sensitive tight sandstone reservoir physical model is obtained. The solidification treatment time is 48 hours, and the solidification treatment temperature is 40°C.

[0056] Embodiment 2-4

[0057] Examples 2-4 all provide a stress-sensitive tight sandstone reservoir physical model material and a method for preparing a stress-sensitive tight sandstone reservoir physical model. The steps of the method are the same as those in Example 1, with the only difference being the amounts of kaolin, polyurethane, and curing agent. The specific amounts of each substance in Examples 2-4 are shown in Table 1.

[0058] Comparative Example

[0059] This comparative example uses a seismic physics model made of hard polymer material (epoxy resin) bonded with quartz sand and kaolin. The specific amount of each material is shown in Table 1.

[0060] Test Case

[0061] This test example tests the porosity and permeability of the stress-sensitive tight sandstone reservoir physical model prepared in Examples 1-4 and the seismic physical model prepared in the comparative example, as shown in Table 1. This test example also uses the ultrasonic transmission method to test the longitudinal wave velocity of the stress-sensitive tight sandstone reservoir physical model prepared in Examples 1-4 and the seismic physical model prepared in the comparative example under a horizontal stress difference of 2MPa, and the obtained longitudinal wave velocity change value under a horizontal stress difference of 2MPa is shown in Table 1. Among them, the unit of porosity is %, the unit of permeability is mD, and the unit of longitudinal wave velocity change value is m / s.

[0062] Table 1 Porosity, permeability and P-wave velocity changes of each model

[0063]

[0064] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a stress-sensitive tight sandstone reservoir physical model using a stress-sensitive tight sandstone reservoir physical model material, characterized in that: The physical model material is composed of the following components by weight: 450-550 parts of quartz sand, 200-500 parts of kaolin, 50-100 parts of polyurethane, 5-10 parts of curing agent, and 5-10 parts of diluent; The particle size of the kaolin is 1100-1400 mesh; The method comprises the following steps: S1: Material pretreatment: heating the polyurethane and curing agent; S2: Mold pretreatment: Perform curing pretreatment on the inner surface of the physical model curing mold; S3: material preparation: uniformly mix the quartz sand and the kaolin, add the polyurethane and curing agent treated in step S1, and the diluent, and uniformly mix to obtain a mixture; S4: Sand plate pressing: placing the mixture into the physical model solidification mold processed in step S2, and pressing the mixture; S5: Sand plate solidification: After the pressing treatment, solidification treatment is performed to obtain the stress-sensitive tight sandstone reservoir physical model.

2. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: The curing agent is an amine curing agent with an amine value of less than 400 mgKOH / g; The diluent is an ester plasticizer.

3. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 2, wherein: The curing agent is cashew nut oil modified fatty amine.

4. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 2, wherein: The diluent is dibutyl phthalate.

5. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: The particle size of the quartz sand is 100-600 meshes; the particle size of the kaolin is 1100-1200 meshes.

6. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 5, wherein: The particle size of the quartz sand is 200-400 meshes.

7. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: In step S1, the temperature of the heating treatment is 40-60°C, and the time of the heating treatment is 1-3 hours.

8. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: In step S2, the curing pretreatment step includes applying silicone rubber to the inner surface of the physical model curing mold, and after the silicone rubber is cured, the curing pretreatment is completed.

9. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: In step S3, the curing agent processed in step S1 and the polyurethane processed in step S1 are uniformly mixed, and then the diluent is added and uniformly mixed, and then added to the material uniformly mixed with the quartz sand and the kaolin to obtain the mixture.

10. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: In step S4, the pressing treatment time is 8-15 min, and the pressing treatment pressure is 8 MPa-14 MPa.

11. The method for preparing a stress-sensitive tight sandstone reservoir physical model according to claim 1, wherein: In step S5, the curing treatment time is 36-60 hours, and the curing treatment temperature is 35-45°C.

12. A stress-sensitive tight sandstone reservoir physical model obtained according to the method for preparing a stress-sensitive tight sandstone reservoir physical model according to any one of claims 1 to 11.

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