Dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production and preparation method thereof

Abstract

The present invention discloses a dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production and a preparation method thereof, and belongs to the technical field of oil and gas field development. The preparation method comprises the following steps: S1: mixing oil-containing mud, skeleton material, binder, sintering aid, fiber and metal salt to obtain slurry; S2: pouring the slurry into a granulator for granulation to obtain proppant pellet embryos; S3: pore-forming sintering of the proppant pellet embryos to obtain ceramsite proppant; S4: coating the ceramsite proppant with resin to obtain coated proppant, which is the dual-function ceramsite. The present invention focuses on the difficulties in shale oil and gas development and oil-containing mud treatment, prepares ceramsite proppant through resource utilization of oil-containing mud and gives it catalytic ability, combines supercritical CO2 fracturing technology, realizes dual functions of fracturing support and underground in-situ cracking hydrogen production, improves oil recovery rate and gas recovery rate, solves H2S pollution problem, and reduces shale oil and gas production cost.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production and a preparation method thereof. Background Art

[0002] As an important unconventional oil and gas resource, shale oil and gas has received widespread attention worldwide. In recent years, with the advancement of hydraulic fracturing technology, the development of shale oil and gas has developed rapidly. However, the development of shale oil and gas still faces a series of technical and environmental challenges. First, shale oil and gas reservoirs have complex reservoir characteristics, such as low permeability, thin layer thickness and dense structure, which restricts the flow of oil and gas and makes it difficult to exploit. Secondly, a large amount of water resources are required during hydraulic fracturing, and the flowback fluid produced contains chemical additives, which will cause environmental pollution if not properly handled. In addition, the technical cost of developing shale oil and gas is high, and a high level of engineering technology is required to ensure economic benefits. Furthermore, the development of shale oil and gas also faces the problem of how to improve the efficiency of water resource utilization, especially in areas with scarce water resources. In addition, some shale oil and gas are accompanied by the production of highly toxic H2S, which must be matched with purification processes, resulting in additional development costs.

[0003] As an innovative method for the exploitation of unconventional oil and gas resources, supercritical carbon dioxide (SC-CO2) fracturing technology has attracted widespread attention worldwide in recent years. This technology utilizes the unique physical and chemical properties of carbon dioxide in a supercritical state to achieve efficient reservoir production at lower pressures, and is particularly suitable for low-permeability shale oil and gas reservoirs. Compared with traditional hydraulic fracturing technology, SC-CO2 fracturing technology can reduce damage to the formation, speed up the return flow, and reduce dependence on water resources, which helps to alleviate the mining difficulties in water-scarce areas. However, supercritical carbon dioxide fracturing technology also needs to be used with proppants to further improve the fracturing effect.

[0004] Oily mud treatment is an important task facing the oil extraction industry, especially with the improvement of environmental protection standards and the increase in public attention to environmental issues, the proper treatment of oily mud has become a problem that enterprises must face. At present, the treatment technologies of oily mud mainly include physical separation, chemical treatment, biodegradation, thermal treatment and solidification stabilization. Despite the diversity of treatment technologies, there are still many difficulties. First, the high cost of treatment, especially for small oil fields or remote areas, the high cost becomes a constraint. Secondly, the treatment efficiency is closely related to the composition of the mud. Different oily muds require different treatment solutions, which poses a challenge to the selection and optimization of the process. Furthermore, some treatment methods may produce new waste or by-products, which require further treatment to meet environmental protection standards. Finally, with the tightening of laws and regulations, how to ensure that the treated mud meets the emission standards is also an urgent problem to be solved. In view of this, the development trend of oily mud treatment technology in the future will be to strive towards more efficient, more economical and more environmentally friendly directions, and at the same time, it is necessary to strengthen the research and development and application of new technologies to cope with increasingly stringent environmental protection requirements. Summary of the invention

[0005] In view of the above problems, the present invention aims to provide a dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production and a preparation method thereof.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, a method for preparing dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production is provided, comprising the following steps:

[0008] S1: mixing oil-containing mud, skeleton material, binder, sintering aid, fiber and metal salt to obtain slurry;

[0009] S2: pouring the slurry into a granulator for granulation to obtain proppant pellet embryos;

[0010] S3: performing pore-forming sintering on the proppant pellet embryo to obtain ceramsite proppant;

[0011] S4: coating the ceramsite proppant with resin to obtain coated proppant, wherein the coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production.

[0012] Preferably, in step S1, the skeleton material is bauxite and / or potassium feldspar, the binder is carboxymethyl cellulose, the sintering aid is dolomite, the fiber is any one or more of basalt fiber, carbon fiber, polyacrylamide fiber, asbestos fiber, and glass fiber, and the metal salt is a mixture of ammonium molybdate and nitrate in a mass ratio of 5 to 10:3.

[0013] Preferably, the nitrate is any one or more of nickel nitrate, cobalt nitrate, manganese nitrate, copper nitrate and iron nitrate.

[0014] Preferably, in step S1, the mass ratio of the oil-containing mud, the skeleton material, the binder, the sintering aid, the fiber and the metal salt is 10-30:50-60:1-2:1-2:2-4:1-2.

[0015] Preferably, in step S2, during granulation, granulation is stopped when the content of particles with a spherical particle size in the range of 1 to 10 microns exceeds 85% of the total particle content.

[0016] Preferably, step S2 further comprises the step of drying the proppant pellets, and during the drying, the moisture content of the proppant pellets is lower than 3%.

[0017] Preferably, in step S3, during the pore-forming sintering, the pores are first formed in a low temperature zone of 200-500°C for 1-5h, then in a high temperature zone of 900-1100°C for 1-5h, and finally kept at 1200-1400°C for 1-5h to obtain the ceramsite proppant.

[0018] Preferably, in step S4, the resin is phenolic resin and / or epoxy resin, and the mass ratio of the ceramsite proppant to the resin is 1-10:1.

[0019] Preferably, in step S4, when coating, the ceramsite proppant is mixed with the resin to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed under a pressure of 1-5 MPa for 1-10 hours, and finally cured at 100-200° C. for 5-50 hours to obtain the coated proppant.

[0020] On the other hand, a shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite prepared by the preparation method of shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite described in any one of the above items is also provided.

[0021] The beneficial effects of the present invention are:

[0022] The present invention focuses on the development of shale oil and gas and the treatment of oil-containing mud. Through the resource utilization of oil-containing mud, it is prepared into ceramsite proppant and endowed with catalytic ability, combined with supercritical CO2 fracturing technology, to achieve the dual functions of fracturing support and underground in-situ cracking hydrogen production, improve oil and gas recovery rates, solve the H2S pollution problem, and reduce the cost of shale oil and gas production. Through underground in-situ cracking hydrogen production, on the one hand, the viscosity of crude oil can be reduced, and the oil and gas recovery rates can be increased; on the other hand, H2S can be decomposed to produce hydrogen through catalytic cracking, which not only solves the H2S pollution problem, but also produces hydrogen energy resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is the SEM image of the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production in Example 1. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, in the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other. It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those commonly understood by those of ordinary skill in the art to which this application belongs. The words "including" or "comprising" and the like used in the disclosure of the present invention mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0026] In one aspect, the present invention provides a method for preparing dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production, comprising the following steps:

[0027] S1: Mixing oil-containing mud, skeleton material, binder, sintering aid, fiber and metal salt to obtain slurry.

[0028] In a specific embodiment, the skeleton material is bauxite and / or potassium feldspar, the binder is carboxymethyl cellulose, the sintering aid is dolomite, the fiber is any one or more of basalt fiber, carbon fiber, polyacrylamide fiber, asbestos fiber, and glass fiber, and the metal salt is a mixture of ammonium molybdate and nitrate in a mass ratio of 5 to 10:3. Optionally, the nitrate is any one or more of nickel nitrate, cobalt nitrate, manganese nitrate, copper nitrate, and iron nitrate.

[0029] In a specific embodiment, the mass ratio of the oil-containing mud, the skeleton material, the binder, the sintering aid, the fiber and the metal salt is 10~30:50~60:1~2:1~2:2~4:1~2.

[0030] S2: pouring the slurry into a granulator for granulation to obtain proppant pellet embryos.

[0031] In a specific embodiment, during granulation, granulation is stopped when the content of particles with a spherical particle size in the range of 1 to 10 microns exceeds 85% of the total particle content.

[0032] In a specific embodiment, the method further comprises the step of drying the proppant pellets, and during the drying process, the moisture content of the proppant pellets is lower than 3%.

[0033] S3: performing pore-forming sintering on the proppant pellet embryo to obtain ceramsite proppant.

[0034] In a specific embodiment, during pore-forming sintering, pores are first formed in a low temperature zone of 200-500°C for 1-5h, then in a high temperature zone of 900-1100°C for 1-5h, and finally kept at 1200-1400°C for 1-5h to obtain the ceramsite proppant.

[0035] In the above embodiment, by first making pores in the low temperature zone, the particle structure can be protected from collapse, especially some mesopores and small pores; if the pores are made directly in the high temperature zone, the material will crack and the pore structure will increase, affecting the performance of the ceramsite proppant.

[0036] In a specific embodiment, the method further comprises the step of sieving the ceramsite proppant to obtain ceramsite proppant of target particle size. Optionally, the target particle size is 40-70 mesh.

[0037] S4: coating the ceramsite proppant with resin to obtain coated proppant, wherein the coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production.

[0038] In a specific embodiment, the resin is phenolic resin and / or epoxy resin, and the mass ratio of the ceramsite proppant to the resin is 1-10:1.

[0039] In a specific embodiment, when coating, the ceramsite proppant is mixed with the resin to obtain a mixture, and the mixture is placed in a pressure vessel, then soaked under a pressure of 1-5 MPa for 1-10 hours, and finally cured at 100-200° C. for 5-50 hours to obtain the coated proppant.

[0040] On the other hand, the present invention also provides a shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite prepared by the preparation method of shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite described in any one of the above.

[0041] In the above embodiments, the dual-function expanded clay for shale oil and gas fracturing and in-situ hydrogen production of the present invention has the following properties: acid solubility is less than 4%, crushing rate is less than 5%, oil recovery rate is greater than 15%, gas recovery rate is greater than 50%, and hydrogen content of hydrogen produced by cracking is greater than 10%.

[0042] Example 1

[0043] A shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite is prepared by the following steps:

[0044] (1) mixing oil-bearing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (basalt fiber) and metal salt (a mixture of ammonium molybdate, nickel nitrate and iron nitrate in a mass ratio of 7:2:1) in a mass ratio of 25:55:1.5:1.5:3.5:1.5 to obtain slurry;

[0045] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0046] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 400° C. for 1.5 h, then pore-formed in a high temperature zone of 1000° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0047] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed under a pressure of 2 MPa for 3 hours, and finally cured at 160° C. for 10 hours to obtain a coated proppant. The coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production.

[0048] Example 2

[0049] A shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite is prepared by the following steps:

[0050] (1) mixing oil-containing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 3:2), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (glass fiber) and metal salt (a mixture of ammonium molybdate, nickel nitrate, iron nitrate and cobalt nitrate in a mass ratio of 7:1:1:1) in a mass ratio of 20:60:1.5:1.5:3:2 to obtain slurry;

[0051] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0052] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 350° C. for 2 hours, then pore-formed in a high temperature zone of 1050° C. for 4 hours, and finally kept at 1250° C. for 3 hours, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0053] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:2 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant. The coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production.

[0054] Example 3

[0055] A shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite is prepared by the following steps:

[0056] (1) mixing oil-containing mud, a skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 1:1), a binder (carboxymethyl cellulose), a sintering aid (dolomite), a fiber (carbon fiber), and a metal salt (a mixture of ammonium molybdate, nickel nitrate, iron nitrate, and copper nitrate in a mass ratio of 7:1:1:1) in a mass ratio of 25:50:2:2:3.5:2 to obtain a slurry;

[0057] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0058] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 350° C. for 2 hours, then pore-formed in a high temperature zone of 1100° C. for 4 hours, and finally kept at 1200° C. for 3 hours, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0059] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 5:2 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed under a pressure of 3 MPa for 2 hours, and finally cured at 140° C. for 20 hours to obtain a coated proppant. The coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production.

[0060] Example 4

[0061] A shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite is prepared by the following steps:

[0062] (1) mixing oil-containing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (asbestos fiber) and metal salt (a mixture of ammonium molybdate, nickel nitrate, manganese nitrate and cobalt nitrate in a mass ratio of 7:1:1:1) in a mass ratio of 27:56:1.5:1.5:3:1.5 to obtain slurry;

[0063] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0064] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 350° C. for 1.5 h, then pore-formed in a high temperature zone of 1050° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0065] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:2 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant. The coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production.

[0066] Comparative Example 1

[0067] A ceramsite proppant is prepared by the following steps:

[0068] (1) mixing a skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), a binder (carboxymethyl cellulose), a sintering aid (dolomite), a fiber (basalt fiber), and a metal salt (a mixture of ammonium molybdate, nickel nitrate, and iron nitrate in a mass ratio of 7:2:1) in a mass ratio of 80:1.5:1.5:3.5:1.5 to obtain a slurry;

[0069] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0070] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 400° C. for 1.5 h, then pore-formed in a high temperature zone of 1000° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0071] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0072] Comparative Example 2

[0073] A ceramsite proppant is prepared by the following steps:

[0074] (1) mixing oil-containing mud, a skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), a binder (carboxymethyl cellulose), a sintering aid (dolomite) and a fiber (basalt fiber) in a mass ratio of 25:55:1.5:1.5:3.5 to obtain a slurry;

[0075] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0076] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 400° C. for 1.5 h, then pore-formed in a high temperature zone of 1000° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0077] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0078] Comparative Example 3

[0079] A ceramsite proppant is prepared by the following steps:

[0080] (1) mixing oil-bearing mud, a skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), a binder (carboxymethyl cellulose), a sintering aid (dolomite), and a metal salt (a mixture of ammonium molybdate, nickel nitrate, and iron nitrate in a mass ratio of 7:2:1) in a mass ratio of 25:55:1.5:1.5:1.5 to obtain a slurry;

[0081] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0082] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 400° C. for 1.5 h, then pore-formed in a high temperature zone of 1000° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0083] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0084] Comparative Example 4

[0085] A ceramsite proppant is prepared by the following steps:

[0086] (1) mixing oil-bearing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (basalt fiber) and metal salt (a mixture of ammonium molybdate, nickel nitrate and iron nitrate in a mass ratio of 7:2:1) in a mass ratio of 25:55:1.5:1.5:3.5:1.5 to obtain slurry;

[0087] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0088] (3) The proppant pellets are first pore-formed in a high temperature zone of 1000° C. for 3 hours, then kept at 1250° C. for 2 hours, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0089] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0090] Comparative Example 5

[0091] A ceramsite proppant is prepared by the following steps:

[0092] (1) mixing oil-bearing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (basalt fiber) and metal salt (a mixture of ammonium molybdate, nickel nitrate and iron nitrate in a mass ratio of 7:2:1) in a mass ratio of 25:55:1.5:1.5:3.5:1.5 to obtain slurry;

[0093] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0094] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 400° C. for 1.5 h, then pore-formed in a high temperature zone of 1000° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0095] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 20:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed under a pressure of 2 MPa for 3 hours, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0096] Comparative Example 6

[0097] A ceramsite proppant is prepared by the following steps:

[0098] (1) mixing oil-bearing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (basalt fiber) and metal salt (a mixture of ammonium molybdate, nickel nitrate and iron nitrate in a mass ratio of 7:2:1) in a mass ratio of 25:55:1.5:1.5:3.5:1.5 to obtain slurry;

[0099] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0100] (3) The proppant pellets are firstly pore-formed in a low temperature zone of 400° C. for 1.5 h, then pore-formed in a high temperature zone of 1000° C. for 3 h, and finally kept at 1250° C. for 2 h, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0101] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 1:2 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed under a pressure of 2 MPa for 3 hours, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0102] Comparative Example 7

[0103] A ceramsite proppant is prepared by the following steps:

[0104] (1) mixing oil-containing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (basalt fiber) and metal salt (ammonium molybdate) in a mass ratio of 25:55:1.5:1.5:3.5:1.5 to obtain slurry;

[0105] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0106] (3) The proppant pellets are firstly subjected to pore formation in a low temperature zone of 400°C for 1.5 hours, then subjected to pore formation in a high temperature zone of 1000°C for 3 hours, and finally subjected to heat preservation at 1250°C for 2 hours, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0107] The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, then immersed for 3 hours under a pressure of 2MPa, and finally cured at 160°C for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0108] Comparative Example 8

[0109] A ceramsite proppant is prepared by the following steps:

[0110] (1) mixing oil-bearing mud, skeleton material (a mixture of bauxite and potassium feldspar in a mass ratio of 2:1), binder (carboxymethyl cellulose), sintering aid (dolomite), fiber (basalt fiber) and metal salt (ammonium molybdate and nickel nitrate in a mass ratio of 1:1) in a mass ratio of 25:55:1.5:1.5:3.5:1.5 to obtain slurry;

[0111] (2) pouring the slurry into a granulator for granulation, stopping granulation and drying when the content of particles with a particle size of 1 to 10 microns exceeds 85% of the total particle content, to obtain proppant pellet embryos with a moisture content of less than 3%;

[0112] (3) The proppant pellets are firstly subjected to pore formation in a low temperature zone of 400°C for 1.5 hours, then subjected to pore formation in a high temperature zone of 1000°C for 3 hours, and finally subjected to heat preservation at 1250°C for 2 hours, cooled, and sieved to obtain 40-70 mesh ceramsite proppant;

[0113] (4) The ceramsite proppant and resin (phenolic resin) are mixed in a mass ratio of 3:1 to obtain a mixture, and the mixture is placed in a pressure vessel, and then immersed for 3 hours under a pressure of 2 MPa, and finally cured at 160° C. for 10 hours to obtain a coated proppant, which is the ceramsite proppant.

[0114] The performance test was performed on the ceramsite proppant of each embodiment and each comparative example, wherein the shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite of the present invention was used for shale oil and gas fracturing and in-situ hydrogen production, which specifically includes the following steps:

[0115] (1) The drilling wells include at least one heat injection well, one injection well and one production well, and the wells are connected by horizontal wells;

[0116] (2) injecting supercritical CO2 into the horizontal well through the injection well to perform staged fracturing, and evenly mixing the shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite with the sand-carrying liquid into the formation to fill the fracturing area;

[0117] (3) After fracturing, hot gas at 450-550°C is injected into the formation through a heat injection well to reach the temperature required for oil and gas cracking to produce hydrogen;

[0118] (4) The cracked shale oil and gas are extracted to the ground, and the liquid and gas are separated and recovered. The liquid is crude oil, and the gas is hydrogen-blended natural gas.

[0119] In the above embodiment, the metal salt in the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production of the present invention will eventually form molybdenum compounds, which can crack the C-H or H-S bonds of methane, olefins or hydrogen sulfide at 450-550°C and underground pressure conditions. The cracked hydrogen atoms combine with each other to form hydrogen, thereby enabling the present invention to produce hydrogen in situ.

[0120] In the performance test results, the SEM image of the dual-function ceramsite of shale oil and gas fracturing and in-situ hydrogen production in Example 1 is as follows: Figure 1 The rest of the performance test results are shown in Table 1:

[0121] Table 1 Performance test results of ceramsite proppant of each embodiment and each comparative example

[0122]

[0123] Note: In Table 1, the differences in brackets of each comparative example refer to the differences compared with Example 1; the crushing rate is the test result under the conditions of closing pressure of 86 MPa and crushing chamber force of 174 kN.

[0124] As can be seen from Table 1, the present invention can improve the oil recovery rate and gas recovery rate of shale oil and gas, and can reduce H2S pollution. When certain components of the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production of the present invention are not included, the ceramsite proppant obtained cannot achieve the dual-function effect of the present invention; when the preparation method of the present invention is not used to prepare ceramsite, the ceramsite proppant obtained cannot achieve the dual-function effect of the present invention.

[0125] It should be noted that the above embodiments are only some embodiments of the present invention. Under the conditions of the preparation method described in the present invention, changing certain parameters therein, such as the selection, dosage, temperature, time, etc. of the reagent, can successfully prepare the shale oil and gas fracturing and in-situ hydrogen production dual-function ceramsite described in the present invention, which can also realize the resource utilization of oil-containing mud, reduce the process flow, reduce the processing cost, and improve the economic value of oil-containing mud; underground in-situ cracking to produce hydrogen, reduce crude oil viscosity, reduce H2S pollution, and improve shale oil and gas recovery rate and gas recovery rate.

[0126] The above description is only a representative embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, uses the above-disclosed technical contents to make some changes or modifications to the embodiments are equivalent embodiments of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production, characterized in that: The following steps are involved: S1: mixing oil-containing mud, skeleton material, binder, sintering aid, fiber and metal salt in a mass ratio of 10-30:50-60:1-2:1-2:2-4:1-2 to obtain slurry; The skeleton material is bauxite and / or potassium feldspar, the binder is carboxymethyl cellulose, the sintering aid is dolomite, the fiber is any one or more of basalt fiber, carbon fiber, polyacrylamide fiber, asbestos fiber, and glass fiber, and the metal salt is a mixture of ammonium molybdate and nitrate in a mass ratio of 5 to 10:3; The nitrate is any one or more of nickel nitrate, cobalt nitrate, manganese nitrate, copper nitrate, and iron nitrate; S2: pouring the slurry into a granulator for granulation to obtain proppant pellet embryos; S3: performing pore-forming sintering on the proppant pellet embryo to obtain ceramsite proppant; S4: coating the ceramsite proppant with resin to obtain coated proppant, wherein the coated proppant is the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production; the resin is phenolic resin and / or epoxy resin, and the mass ratio of the ceramsite proppant to the resin is 1-10:

1.

2. The method for preparing the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production according to claim 1, characterized in that: In step S2, during granulation, granulation is stopped when the content of particles with a spherical particle size in the range of 1 to 10 microns exceeds 85% of the total particle content.

3. The method for preparing the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production according to claim 2, characterized in that: Step S2 further includes the step of drying the proppant pellets, and during the drying process, the moisture content of the proppant pellets is reduced to less than 3%.

4. The method for preparing the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production according to claim 1, characterized in that: In step S3, during the pore-forming sintering, pores are first formed in a low temperature zone of 200-500°C for 1-5h, then in a high temperature zone of 900-1100°C for 1-5h, and finally kept at 1200-1400°C for 1-5h to obtain the ceramsite proppant.

5. The method for preparing the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production according to claim 1, characterized in that: In step S4, when coating, the ceramsite proppant is mixed with the resin to obtain a mixture, and the mixture is placed in a pressure vessel, then soaked under a pressure of 1-5 MPa for 1-10 hours, and finally cured at 100-200° C. for 5-50 hours to obtain the coated proppant.

6. A dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production, characterized in that: The invention is prepared by the preparation method of the dual-function ceramsite for shale oil and gas fracturing and in-situ hydrogen production according to any one of claims 1 to 5.

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