Phase-change material filled pore type reservoir artificial core and preparation method and application thereof

Abstract

The invention belongs to the field of seismic physical models, and discloses a phase-change material filled pore type reservoir artificial core and a preparation method and application thereof. The method comprises the following steps: uniformly mixing quartz sand and a cementing agent to obtain a cementing material; injecting the cementing material into a mold, and sequentially pressing, curing, demolding and polishing to obtain a cured artificial rock core; mixing the cured artificial rock core with a phase change material which is heated and molten into a liquid state to obtain a mixed system; the mixed system is vacuumized under the vacuum degree condition of-98 kPa to-100 kPa, pores of the solidified artificial rock core are filled with the phase-change material which is heated and melted into the liquid state, and the phase-change material filled pore type reservoir artificial rock core is obtained. The prepared phase change material filled pore type reservoir artificial core is good in sound wave penetrability and stable in wave velocity, and can be used for reservoir fluid seismic physical model forward modeling method research.

Description

Technical Field

[0001] The present invention belongs to the field of seismic physical models, and more specifically, relates to an artificial core of a pore-type reservoir filled with a phase change material, a preparation method thereof, and an application thereof. Background Art

[0002] For the production of conventional physical models, composite materials meeting the requirements of acoustic wave propagation velocity can be prepared using polymer materials such as epoxy resin and silicone rubber, and then complex two-dimensional or three-dimensional structure models can be made through processing, carving and other techniques, meeting the simulation research of complex surfaces and complex structures. However, the research on the materials for simulating reservoir fluids is relatively weak. The simulation materials not only need to have certain pore characteristics, but also need to have the function of being saturated with fluids. The production methods and processes are relatively complex, which has become a bottleneck restricting the further development of physical model technology. In addition, with the development of exploration technology, the research on the target layers in oil and gas reservoir areas has become a hot topic. Mathematical simulation has a certain flexibility in forward simulation, but it is difficult to establish a mathematical model for reservoir fluid geological bodies. Physical simulation technology is more intuitive and closer to actual field exploration. The key to constructing a suitable reservoir fluid model lies in the development of reservoir fluid materials. Therefore, selecting or formulating model materials that can be analogous to natural reservoir fluid geology and making a realistic reservoir model is one of the key issues for the success of seismic physical simulation technology.

[0003] With the continuous deepening of oil and gas exploration and development work, the exploration targets and development environments faced are becoming more and more complex. In the northwest, southwest, north China and other regions, the reservoir types are mostly fracture-type, pore-type, tight pore-type or superposition of various complex media, all facing the problem that the seismic response characteristics of fluids in complex media reservoirs are not clear, resulting in unclear fluid prediction mechanisms. In addition, there are also phase changes during the oil and gas production process. The phase change of fluids will have a greater impact on the reservoir leakage rate and the reservoir development process. For example, the exploitation of natural gas hydrates in permafrost areas mainly adopts the thermal stimulation method or the pressure reduction method, which is a process of decomposition of solid hydrates into liquid and gas. The development of heavy oil reservoirs also has a solid-liquid phase change process. Heavy oil reservoirs are difficult to develop because they contain heavy components with high density, high viscosity and poor fluidity such as resins and asphaltenes. The current key research and development field is to reduce the viscosity of crude oil by heating to improve its fluidity in the formation, which involves the transformation from solid phase to liquid phase. To sum up, the research on the model materials and preparation methods of phase change materials filled in reservoir pores is of great significance for oil and gas exploration and development facing reservoir fluids. Summary of the Invention

[0004] The object of the present invention is to provide a phase change material-filled pore-type reservoir artificial core, a preparation method and an application thereof in view of the deficiencies of the prior art. The phase change material-filled pore-type reservoir artificial core prepared by the present invention has good acoustic wave penetrability and stable wave velocity, and can be used for the forward modeling method research of reservoir fluid seismic physical models.

[0005] To achieve the above object, in the first aspect of the present invention, a preparation method of a phase change material-filled pore-type reservoir artificial core is provided, and the method includes the following steps:

[0006] S1: Mix quartz sand and a cementing agent evenly to obtain a cementing material; inject the cementing material into a mold, and successively perform pressing, curing, demolding and polishing to obtain a cured artificial core;

[0007] S2: Mix the cured artificial core with a phase change material heated and melted into a liquid state to obtain a mixed system; place the mixed system under a vacuum condition of -98 to -100 kPa to perform vacuum treatment, so that the phase change material heated and melted into a liquid state fills the pores of the cured artificial core to obtain the phase change material-filled pore-type reservoir artificial core.

[0008] In the second aspect of the present invention, a phase change material-filled pore-type reservoir artificial core prepared by the above preparation method is provided.

[0009] In the third aspect of the present invention, an application of the phase change material-filled pore-type reservoir artificial core in the forward modeling method research of reservoir fluid seismic physical models is provided.

[0010] The beneficial effects of the technical solution of the present invention are as follows:

[0011] The present invention uses a vacuum filling method to fill liquid Fischer-Tropsch wax into the pores of an artificial core to simulate a reservoir containing a phase change fluid. Experimental results show that the phase change material-filled pore-type reservoir artificial core prepared by the present invention has good acoustic wave penetrability and stable wave velocity, can be used for the forward modeling method research of reservoir fluid seismic physical models, and provides a scientific basis for the correctness and reliability of reservoir fluid geophysical characterization.

[0012] Other features and advantages of the present invention will be described in detail in the following specific implementation manner. Description of the Drawings

[0013] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features and advantages of the present invention will become more obvious, wherein, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0014] Figure 1The flowchart of a preparation method of an artificial core of a phase change material-filled porous reservoir provided in Embodiment 1 of the present invention is shown.

[0015] Figure 2 The CT scan sectional view of the artificial core of the phase change material-filled porous reservoir prepared by the preparation method of the artificial core of the phase change material-filled porous reservoir provided in Embodiment 1 of the present invention is shown.

[0016] Figure 3 The CT scan sectional view of the solidified artificial core obtained in Step 3 of the preparation method of the artificial core of the phase change material-filled porous reservoir provided in Embodiment 1 of the present invention is shown.

[0017] Figure 4 The longitudinal and transverse wave acoustic penetration test results of the artificial cores prepared in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention are shown. Specific Embodiments

[0018] 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.

[0019] The first aspect of the present invention provides a preparation method of an artificial core of a phase change material-filled porous reservoir, and the method includes the following steps:

[0020] S1: Mix quartz sand and a cementing agent evenly to obtain a cementing material; inject the cementing material into a mold, and successively perform pressing, curing, demolding, and polishing to obtain a solidified artificial core;

[0021] S2: Mix the solidified artificial core with a phase change material melted into a liquid state to obtain a mixed system; place the mixed system under a vacuum condition of -98 to -100 kPa for vacuum pumping treatment, so that the phase change material melted into a liquid state fills the pores of the solidified artificial core to obtain the artificial core of the phase change material-filled porous reservoir.

[0022] According to the present invention, preferably, the dosage ratio of the quartz sand, the cementing agent, and the phase change material is (80 - 120):(2 - 20):(80 - 120).

[0023] According to the present invention, preferably, the vacuum pumping time is 8 - 20 min, and preferably, the vacuum pumping time is 15 min.

[0024] According to the present invention, preferably, the particle size of the quartz sand is 60-140 mesh, and preferably, the particle size of the quartz sand is 100 mesh.

[0025] In the present invention, as a preferred embodiment, the origin of the quartz sand is Hebei.

[0026] According to the present invention, preferably, the binder comprises the following components by weight: 6-10 parts of a first epoxy resin and 2-6 parts of a curing agent.

[0027] According to the present invention, preferably, the first epoxy resin is a bisphenol A liquid epoxy resin, with an epoxy equivalent of 184-195 g / mol and a viscosity of 10000-16000 mPas at 25°C.

[0028] According to the present invention, preferably, based on the total weight of the curing agent, the curing agent comprises: 50-60 wt% of isophorone diamine, 20-25 wt% of benzyl alcohol, and 20-25 wt% of a second epoxy resin.

[0029] In the present invention, as a preferred embodiment, the curing agent is the R-2269 type curing agent of Ricky New Materials (Guangzhou) Co., Ltd.

[0030] According to the present invention, preferably, the phase change material is Fischer-Tropsch wax and / or paraffin wax.

[0031] According to the present invention, preferably, the melting point of the Fischer-Tropsch wax is 32-80°C, preferably 40°C.

[0032] In the present invention, Fischer-Tropsch wax is a methylene polymer, an alkane polymer synthesized from hydrocarbon-based syngas or natural gas, with a molecular weight much lower than that of ordinary paraffin wax, fewer branched chains, high crystallinity, and is easily infiltrated into high-viscosity macromolecular chains, significantly reducing the melt viscosity. Fischer-Tropsch wax is a mixture and has no fixed melting point. The melting point referred to in the present invention is the temperature at which the first stagnation period appears on the cooling curve under specified conditions.

[0033] According to the present invention, preferably, before injecting the cementitious material into the mold, a release coating is applied to the inner surface of the mold, and the mold after applying the release coating is placed in a dry and ventilated place for standby.

[0034] In the present invention, as a preferred embodiment, the material of the release coating is vaseline.

[0035] In the present invention, as a preferred embodiment, the method for preparing the phase change material-filled pore-type reservoir artificial core specifically comprises the following steps:

[0036] 1. Mold pretreatment

[0037] After the mold is fabricated, clean the mold with alcohol, apply a layer of vaseline on the inner surface of the mold as a demolding coating, and place the treated mold in a dry and ventilated place for standby.

[0038] 2. Artificial core preparation

[0039] Measure quartz sand and cementing agent in proportion and mix them evenly to obtain a cementing material; layer by layer place the cementing material into the mold, and finally place the mold under a fixed pressure and press for 24 hours until the quartz sand solidifies into rock.

[0040] 3. Curing and demolding

[0041] Take out the cured artificial core in the mold and polish the end face to obtain a cured artificial core (i.e., artificial sandstone).

[0042] 4. Phase change material pretreatment

[0043] Place the phase change material in a solid state at room temperature and heat it to melt it into a liquid state at the melting point temperature.

[0044] 5. Vacuum filling of phase change material into artificial core

[0045] Place the cured artificial core into the phase change material melted into a liquid state to obtain a mixed system; place the mixed system under a vacuum degree of -99 kPa for vacuum pumping treatment to facilitate the filling of the phase change material melted into a liquid state into the pores of the cured artificial core, and obtain the phase change material filled pore type reservoir artificial core (i.e., the artificial core saturated with the phase change material).

[0046] The second aspect of the present invention provides the phase change material filled pore type reservoir artificial core prepared by the preparation method described above.

[0047] The third aspect of the present invention provides the application of the phase change material filled pore type reservoir artificial core in the forward modeling method research of reservoir fluid seismic physical models.

[0048] The following specifically illustrates the present invention through examples.

[0049] In the following respective examples:

[0050] The particle size of the quartz sand is 100 mesh, and the origin is Hebei.

[0051] The cementing agent includes the following components by weight: 8 parts of the first epoxy resin and 4 parts of the R-2269 type curing agent. The first epoxy resin is a bisphenol A type liquid epoxy resin, with an epoxy equivalent of 184 - 195 g / mol and a viscosity of 10000 - 16000 mPas at 25°C.

[0052] The Fischer-Tropsch wax is produced by Zhejiang Huangxing Chemical Co., Ltd. and has a melting point of 40°C.

[0053] Example 1

[0054] This example provides a method for preparing an artificial core of a phase change material-filled porous reservoir, as Figure 1 shown, the method includes the following steps:

[0055] 1. Mold pretreatment

[0056] After the mold is made, clean the mold with alcohol, apply a layer of vaseline on the inner surface of the mold as a demolding coating, and place the treated mold in a dry and ventilated place for standby.

[0057] 2. Preparation of artificial core

[0058] Weigh quartz sand and cementing agent in proportion and mix them evenly to obtain a cementing material; layer the cementing material into the mold, and finally place the mold under a fixed pressure for 24 hours until the quartz sand solidifies into rock.

[0059] 3. Curing and demolding

[0060] Take out the solidified artificial core in the mold and polish the end face to obtain a solidified artificial core (i.e., artificial sandstone).

[0061] 4. Pretreatment of phase change material

[0062] Place the Fischer-Tropsch wax in a solid state at room temperature and heat it to melt it into a liquid state at its melting point.

[0063] 5. Vacuum filling of phase change material into artificial core

[0064] Place the solidified artificial core into the melted Fischer-Tropsch wax in a liquid state to obtain a mixed system; place the mixed system under a vacuum degree of -99 kPa for vacuum treatment to facilitate filling the melted phase change material into the pores of the solidified artificial core to obtain the artificial core of the phase change material-filled porous reservoir (i.e., the artificial core saturated with the phase change material).

[0065] In this example, the dosage ratio of the quartz sand, the first epoxy resin, the R-2269 curing agent, and the Fischer-Tropsch wax is 100:8:4:100.

[0066] In this example, the vacuuming time is 15 min.

[0067] Example 2

[0068] This example provides a method for preparing an artificial core of a phase change material-filled porous reservoir, and the method includes the following steps:

[0069] 1. Mold pretreatment

[0070] After the mold is fabricated, clean the mold with alcohol, and then apply a layer of vaseline on the inner surface of the mold as a demolding coating. Place the treated mold in a dry and well-ventilated place for standby.

[0071] 2. Artificial core preparation

[0072] Measure quartz sand and cementing agent in proportion and mix them evenly to obtain cementing materials. Layer by layer, put the cementing materials into the mold, and finally place the mold under a fixed pressure for pressing for 24 hours until the quartz sand solidifies into rock.

[0073] 3. Curing and demolding

[0074] Take out the solidified artificial core in the mold and polish the end face to obtain the solidified artificial core (i.e., artificial sandstone).

[0075] 4. Phase change material pretreatment

[0076] Place the paraffin wax in a solid state at room temperature and heat it to melt into a liquid state at its melting point.

[0077] 5. Vacuum filling of phase change material into artificial core

[0078] Place the solidified artificial core into the paraffin wax melted into a liquid state to obtain a mixed system. Place the mixed system under a vacuum degree of -99 kPa for vacuum pumping treatment to facilitate the filling of the phase change material melted into a liquid state into the pores of the solidified artificial core, and obtain the phase change material-filled pore-type reservoir artificial core (i.e., the artificial core saturated with the phase change material).

[0079] In this embodiment, the dosage ratio of the quartz sand, the first epoxy resin, the R-2269 type curing agent, and the paraffin wax is 100:8:4:100.

[0080] In this embodiment, the vacuum pumping time is 15 min.

[0081] Example 3

[0082] This embodiment provides a preparation method of a phase change material-filled pore-type reservoir artificial core. The difference between this embodiment and Example 1 is only that:

[0083] The vacuum pumping time is 10 min.

[0084] Example 4

[0085] This embodiment provides a preparation method of a phase change material-filled pore-type reservoir artificial core. The difference between this embodiment and Example 1 is only that:

[0086] The vacuum pumping time is 12 min.

[0087] Example 5

[0088] This example provides a method for preparing an artificial core of a phase change material-filled porous reservoir. The difference between this example and Example 1 is only that:

[0089] The time for evacuation is 18 minutes.

[0090] Comparative Example 1

[0091] 1. Mold pretreatment

[0092] After the mold is fabricated, clean the mold with alcohol, apply a layer of vaseline on the inner surface of the mold as a release coating, and place the treated mold in a dry and well-ventilated place for standby.

[0093] 2. Phase change material pretreatment

[0094] Cut the Fischer-Tropsch wax into small particles with a particle size less than 1 mm.

[0095] 3. Artificial core preparation

[0096] Measure quartz sand, Fischer-Tropsch wax particles and binder in proportion, mix them evenly to obtain a cementitious material; layer the cementitious material into the mold, and finally place the mold under a fixed pressure for 24 hours until the quartz sand solidifies into rock.

[0097] 3. Curing and demolding

[0098] Take out the cured artificial core in the mold and polish the end face to obtain a cured artificial core (i.e., artificial sandstone).

[0099] In this example, the dosage ratio of the quartz sand, the first epoxy resin, the R-2269 curing agent and the paraffin wax is 100:8:4:100.

[0100] Comparative Example 2

[0101] 1. Mold pretreatment

[0102] After the mold is fabricated, clean the mold with alcohol, apply a layer of vaseline on the inner surface of the mold as a release coating, and place the treated mold in a dry and well-ventilated place for standby.

[0103] 3. Phase change material pretreatment

[0104] Place the Fischer-Tropsch wax in a solid state at room temperature and heat it to melt it into a liquid state at the melting point temperature.

[0105] 3. Artificial core preparation

[0106] Measure quartz sand, Fischer-Tropsch wax liquid and binder in proportion, mix them evenly to obtain a cementing material; layer the cementing material into a mold, and finally place the mold under a fixed pressure for 24 hours until the quartz sand solidifies into rock.

[0107] 3. Curing and demolding

[0108] Take out the solidified artificial core in the mold and polish the end face to obtain a solidified artificial core (i.e., artificial sandstone).

[0109] In this embodiment, the dosage ratio of the quartz sand, the first epoxy resin, the R-2269 curing agent and the paraffin wax is 100:8:4:100.

[0110] Test example

[0111] In this test example, CT scans were performed on the solidified artificial core obtained in step 3 of Example 1 and the artificial core of the phase change material-filled pore type reservoir prepared in Example 1, and CT scan slices were obtained respectively, as Figures 2-3 shown. It can be seen that after the artificial core is filled with the phase change material, the area of the black dots in the field of view is significantly reduced, that is, the pore area is reduced, indicating that the pores are occupied by the phase change material.

[0112] This test example also performed longitudinal and transverse wave acoustic penetrability tests on the artificial cores prepared in each example and comparative example. The waveforms of Example 1 and Comparative Examples 1 and 2 are as Figure 4 shown, and the wave velocity calculation results are shown in Table 1. It can be seen that the acoustic penetrability of the cores obtained in Comparative Example 1 and Comparative Example 2 is poor, and the first arrival time cannot be read, so the acoustic wave propagation velocity in the core cannot be calculated. The measured values in Example 2 vary greatly and the wave velocity is unstable. While the acoustic penetrability of Example 1 is good, and the error of multiple measurement results is small and the wave velocity is stable. In addition, from the test results of Examples 1, 3, 4, and 5, it can be seen that the core wave velocity is related to the vacuum pumping time. This is because the longer the vacuum pumping time, the more phase change material is filled into the core, thus making the wave velocity larger. When the vacuum pumping time reaches 15 minutes, the pores in the core that can be filled with the phase change material are basically saturated, and extending the vacuum pumping time will not increase the core wave velocity.

[0113] Table 1

[0114]

[0115]

[0116] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A preparation method of an artificial core for a phase change material-filled pore type reservoir, characterized in that, the method comprises the following steps: S1: Mix quartz sand and a cementing agent evenly to obtain a cementing material; inject the cementing material into a mold, and successively carry out pressing, curing, demolding and polishing to obtain a solidified artificial core; S2: Mix the solidified artificial core with a phase change material melted into a liquid state to obtain a mixed system; carry out a vacuum treatment on the mixed system under a vacuum degree condition of -98 to -100 kPa, so that the phase change material melted into a liquid state fills the pores of the solidified artificial core to obtain the artificial core for the phase change material-filled pore type reservoir.

2. The preparation method according to claim 1, wherein, the dosage ratio of the quartz sand, the cementing agent and the phase change material is (80 - 120):(2 - 20):(80 - 120); the vacuum pumping time is 8 - 20 min, preferably, the vacuum pumping time is 15 min.

3. The preparation method according to claim 1 or 2, wherein, the particle size of the quartz sand is 60 - 140 mesh.

4. The preparation method according to claim 1 or 2, wherein, the cementing agent comprises the following components in parts by weight: 6 - 10 parts of a first epoxy resin and 2 - 6 parts of a curing agent.

5. The preparation method according to claim 4, wherein, the first epoxy resin is a bisphenol A type liquid epoxy resin, with an epoxy equivalent of 184 - 195 g / mol and a viscosity of 10000 - 16000 mPas at 25°C; based on the total weight of the curing agent, the curing agent comprises: 50 - 60 wt% of isophorone diamine, 20 - 25 wt% of benzyl alcohol and 20 - 25 wt% of a second epoxy resin.

6. The preparation method according to claim 1 or 2, wherein, the phase change material is Fischer-Tropsch wax and / or paraffin wax.

7. The preparation method according to claim 6, wherein, the melting point of the Fischer-Tropsch wax is 32 - 80°C, preferably 40°C.

8. The preparation method according to claim 1, wherein, before injecting the cementing material into the mold, apply a demolding coating on the inner surface of the mold.

9. An artificial core for a phase change material-filled pore type reservoir prepared by the preparation method according to any one of claims 1 - 8.

10. Application of the artificial core for a phase change material-filled pore type reservoir according to claim 9 in the forward modeling method research of reservoir fluid seismic physical models.

Images