Fiber-reinforced inorganic gel plugging agent and preparation method thereof

Abstract

The invention discloses a fiber-reinforced inorganic gel profile control agent and a preparation method, and belongs to the technical field of profile control operation of complex stratum.The fiber-reinforced inorganic gel profile control agent comprises a silicic acid main agent, micro-nano fibers, a cross-linking agent and auxiliaries; the silica gel comprises the following raw materials in percentage by mass: 1%-5% of a silicic acid main agent, 0.1%-5% of a cross-linking agent, 0.1%-0.3% of micro-nano fibers, 0%-0.5% of an auxiliary agent and the balance of water. Micro-nano fibers are added into the silicic acid main agent and the auxiliary agent to form a plugging and control system aqueous solution, the plugging and control system aqueous solution is mixed with the cross-linking agent to form the inorganic gel plugging and control agent with a three-dimensional network structure, the gel strength is enhanced by the three-dimensional network structure, the gel stability is obviously improved, and the compatibility with a high-temperature and high-salinity environment is relatively good. The initial viscosity of the fiber-reinforced inorganic gel is low, the strength can be adjusted according to requirements, the preparation process is simple, the fiber-reinforced inorganic gel is easy to pump in, and on-site construction is facilitated. The cost and the raw material price are low.

Description

Technical Field

[0001] The present invention belongs to the technical field of plugging and profile control operations in complex formations, and particularly relates to a fiber-reinforced inorganic gel plugging and profile control agent and a preparation method thereof. Background Art

[0002] For waterflooding oilfields, the reservoir is affected by the original heterogeneity, and with the long-term water flooding between oil and water wells, the seepage channels are continuously washed by water, the cement between the rock skeletons is continuously scoured, and the sand grains fall off and migrate. Water flow dominant channels are gradually formed in the reservoir, resulting in inefficient or ineffective circulation of the injected water, seriously affecting the water flooding development effect. At present, the deep profile control and fluid diversion technology has become an important means to improve the water flooding effect of high water cut oilfields, but the plugging and profile control problems in high-temperature and high-salinity heterogeneous reservoirs are still technical problems to be solved urgently. There are many types of existing plugging agents in oilfields. The commonly used cross-linked polymer gel at present belongs to a continuous phase plugging agent and has good plugging ability. However, the conventional cross-linked polymer gel has certain limitations in terms of stability and compatibility with formation water under high-temperature and high-salinity reservoir conditions, and has poor resistance to temperature and divalent ions, making it difficult to adapt to special reservoir conditions such as high temperature, high salt, deep wells and ultra-deep wells. Summary of the Invention

[0003] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a fiber-reinforced inorganic gel plugging and profile control agent and a preparation method thereof, so as to solve the technical problems in the prior art that the conventional cross-linked polymer gel has low stability and compatibility with formation water under high-temperature and high-salinity reservoir conditions, poor resistance to temperature and divalent ions, and is difficult to adapt to special reservoir conditions such as high temperature, high salt, deep wells and ultra-deep wells.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A fiber-reinforced inorganic gel plugging and profile control agent, the raw material composition of which includes 1% - 5% of silicate main agent, 0.1% - 5% of cross-linking agent, 0.1% - 0.3% of micro-nano fibers and 0% - 0.5% of auxiliary agent, and the rest is water.

[0006] Preferably, the silicate main agent is sodium silicate or sodium metasilicate.

[0007] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent includes the following steps:

[0008] Dissolve 1% - 5% of silicate main agent and 0% - 0.5% of auxiliary agent in water, and stir until completely dissolved to form a silicate solution;

[0009] Disperse 0.1% - 0.3% of micro-nano fibers in the silicate solution to form an aqueous solution of a plugging and profile control system;

[0010] Add 0.1% - 5% of crosslinking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and let it stand to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0011] Preferably, the silicate main agent is sodium silicate or sodium metasilicate.

[0012] Preferably, the crosslinking agent is at least one of magnesium sulfate, magnesium chloride, and calcium chloride.

[0013] Preferably, the auxiliary agent is a mixture of nitrilotriacetic acid and diethylenetriaminepentaacetic acid.

[0014] Preferably, the mixing mass ratio of nitrilotriacetic acid to diethylenetriaminepentaacetic acid is 2:1.

[0015] Preferably, after adding 0.1% - 5% of crosslinking agent and stirring until completely dissolved, a white solution is formed, and it is left to stand at a set temperature and for a set time to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0016] Preferably, the set temperature is from room temperature to 180°C.

[0017] Preferably, the set time is 1 - 6 h.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The fiber-reinforced inorganic gel plugging and profile control agent provided by the present invention uses a silicate main agent as the main raw material, adds micro-nano fibers, a crosslinking agent, and an auxiliary agent to form a fiber-reinforced inorganic gel. The fiber-reinforced inorganic gel of the present invention has a low initial viscosity, can adjust the strength according to requirements, has a simple preparation process, is easy to pump in, and is convenient for on-site construction. It has a low cost and low raw material prices. The inorganic gel formed by silicate further enhances the three-dimensional network structure of the filled gel, enhances the gel strength, significantly improves the gel stability performance, and has good compatibility with high-temperature and high-salinity environments.

[0020] A preparation method of a fiber-reinforced inorganic gel profile control and water shutoff agent disclosed by the present invention uses a silicate main agent as the main raw material, and adds micro-nano fibers, a crosslinking agent and an auxiliary agent to form a fiber-reinforced inorganic gel profile control and water shutoff agent. The aqueous solution of this profile control and water shutoff system is transparent, and its density and viscosity are close to those of water. After mixing with the crosslinking agent, it forms a white solution, and a milky white gel is formed after standing. This system uses fibers as the skeleton and gradually forms a fiber-reinforced inorganic gel layer by means of adsorption. The physical and chemical properties of the micro-nano fibers are stable. Dispersed in the silicate solution, they are bent, curled and helically crossed, and are intertwined with each other to form a three-dimensional network structure inorganic gel system under the action of the crosslinking agent. In the formation, an inorganic gel can also be gradually formed on the surface of the rock and gravel skeleton. Moreover, the high salinity ions in the formation water are the crosslinking components of the system, which is beneficial to the formation of the gel. The provided fiber-reinforced inorganic gel profile control and water shutoff agent is applicable to different types of medium-high water cut oil reservoirs such as sandstone, conglomerate and low permeability. It has obvious technical advantages in terms of injectability, stability, production cost control and meeting environmental protection requirements, and is suitable for profile control and water shutoff and profile control flooding applications in various reservoirs. The overall level reaches the international leading level. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the microscopic structure of the fiber-reinforced inorganic gel profile control and water shutoff agent of the present invention;

[0022] Figure 2 is a G′ graph of fiber-reinforced inorganic gels with different concentrations and 5% conventional inorganic gels under different f conditions of the present invention;

[0023] Figure 3 is a G″ graph of fiber-reinforced inorganic gels with different concentrations and 5% conventional inorganic gels under different f conditions of the present invention;

[0024] Figure 4 is a G′ graph of fiber-reinforced inorganic gels with different concentrations under different stress conditions of the present invention;

[0025] Figure 5 is a G″ graph of fiber-reinforced inorganic gels with different concentrations under different stress conditions of the present invention.

[0026] Among them, 1-three-dimensional network structure; 2-inorganic gel; a-5% silicate main agent + 5% crosslinking agent; b-5% silicate main agent + 2.5% crosslinking agent; c-3% silicate main agent + 1.5% crosslinking agent; d-2% silicate main agent + 1% crosslinking agent; e-5% conventional inorganic gel. DETAILED DESCRIPTION OF THE INVENTION

[0027] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings:

[0030] In view of the characteristics of high-temperature and high-salinity reservoirs, the present invention makes full use of the ions in high-salinity formation water and develops a fiber-reinforced inorganic gel plugging and diverting agent. This diverting agent has the characteristics of simple construction process, safety and environmental protection, temperature and salt resistance, and is not limited by water quality salinity. The formed fiber-reinforced inorganic gel has good erosion resistance and is stable for a long time under formation conditions, and can be used for plugging and diverting operations in various complex formations.

[0031] The present application discloses a fiber-reinforced inorganic gel plugging and diverting agent, comprising: a silicate main agent, micro-nano fibers, a crosslinking agent and an auxiliary agent; the raw material composition includes 1% to 5% of the silicate main agent, 0.1% to 5% of the crosslinking agent, 0.1% to 0.3% of the micro-nano fibers and 0% to 0.5% of the auxiliary agent by mass ratio, and the rest is water. Micro-nano fibers are added to the silicate main agent and the auxiliary agent to form an aqueous solution of the plugging and diverting system. After mixing with the crosslinking agent, an inorganic gel plugging and diverting agent with a three-dimensional network structure is formed. See Figure 1 , the three-dimensional network structure enhances the gel strength, the gel stability performance is significantly improved, and it has good compatibility with the high-temperature and high-salinity environment. Moreover, the fiber-reinforced inorganic gel of the present invention has a low initial viscosity, can adjust the strength according to requirements, has a simple preparation process, is easy to pump in, and is convenient for on-site construction. It has low cost and low raw material prices.

[0032] In some embodiments, the silicate main agent is sodium silicate or sodium metasilicate.

[0033] The fiber-reinforced inorganic gel plugging and profile control agent provided by the present invention is mainly made of a silicate main agent, and micro-nano fibers, a cross-linking agent and an auxiliary agent are added to form a fiber-reinforced inorganic gel. The fiber-reinforced inorganic gel of the present invention has a low initial viscosity, can adjust the strength according to requirements, has a simple preparation process, is easy to pump in, and is convenient for on-site construction. It has a low cost and the raw materials are inexpensive. The inorganic gel formed by silicate further enhances the three-dimensional network structure of the filled gel, enhances the gel strength, significantly improves the gel stability performance, and has good compatibility with high-temperature and high-salinity environments.

[0034] The present invention also discloses a preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, which includes the following steps:

[0035] S1: Dissolve 1% - 5% of the silicate main agent and 0% - 0.5% of the auxiliary agent in water, and stir until completely dissolved to form a silicate solution;

[0036] In some embodiments, the silicate main agent is sodium silicate or sodium metasilicate.

[0037] In some embodiments, the auxiliary agent is a mixture of nitrilotriacetic acid and diethylenetriaminepentaacetic acid, and the mixing mass ratio is 2:1.

[0038] S2: Disperse 0.1% - 0.3% of the micro-nano fibers in the silicate solution to form an aqueous plugging and profile control system solution;

[0039] S3: Add 0.1% - 5% of the cross-linking agent to the aqueous plugging and profile control system solution, stir until completely dissolved, and let it stand to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0040] In some embodiments, the cross-linking agent is at least one of magnesium sulfate, magnesium chloride, and calcium chloride.

[0041] In some embodiments, after adding 0.1% - 5% of the cross-linking agent and stirring until completely dissolved, a white solution is formed, and after standing, an inorganic gel plugging and profile control agent with a three-dimensional network structure is obtained.

[0042] Preferably, after adding 0.1% - 5% of the cross-linking agent and stirring until completely dissolved, it stands at room temperature to 180 °C to form an inorganic gel plugging and profile control agent.

[0043] Preferably, it stands for 1 - 6 h to form an inorganic gel plugging and profile control agent.

[0044] In some embodiments, the micro-nano fibers used in the present invention are an inorganic fiber, which is a green and environmentally friendly material without environmental pollution. It can withstand a temperature of 1000 °C, and its physical and chemical properties are not affected by salinity.

[0045] The fiber-reinforced inorganic gel provided by the present invention is based on Na 2O·mSiO 2 Using mSiO as the main raw material, adding micro-nano fibers, cross-linking agents and additives to form a fiber-reinforced inorganic gel plugging and profile control agent. The aqueous solution of this plugging and profile control system is transparent, and its density and viscosity are close to those of water. After mixing with the cross-linking agent, it forms a white solution, and can form a milky white gel after 1 - 6 hours at room temperature to 180°C. This system uses fibers as the skeleton and gradually forms a fiber-reinforced inorganic gel layer by means of adsorption. The physical and chemical properties of micro-nano fibers are stable. Dispersed in the silicate solution, they bend, curl and cross helically with each other and form an inorganic gel system with a three-dimensional network structure under the action of the cross-linking agent. In the formation, it can also gradually form inorganic gel on the surface of the rock and gravel skeleton. Moreover, the high salinity ions in the formation water are the cross-linking components of the system, which is beneficial to the formation of the gel.

[0046] Example 1:

[0047] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, comprising the following steps:

[0048] S1: Dissolve 5% of the silicic acid main agent and 0.5% of the additive in water, and stir until completely dissolved to form a silicate solution;

[0049] S2: Disperse 0.3% of micro-nano fibers in the silicate solution to form an aqueous solution of the plugging and profile control system;

[0050] S3: Add 5% of the cross-linking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and a milky white gel can be formed after 5 hours at 170°C, thus obtaining an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0051] Example 2:

[0052] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, comprising the following steps:

[0053] S1: Dissolve 5% of the silicic acid main agent and 0.5% of the additive in water, and stir until completely dissolved to form a silicate solution;

[0054] S2: Disperse 0.3% of micro-nano fibers in the silicate solution to form an aqueous solution of the plugging and profile control system;

[0055] S3: Add 2.5% of the cross-linking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and a milky white gel can be formed after 6 hours at 170°C, thus obtaining an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0056] Example 3:

[0057] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, comprising the following steps:

[0058] S1: Dissolve 3% of the silicate main agent and 0.3% of the auxiliary agent in water, and stir until completely dissolved to form a silicate solution;

[0059] S2: Disperse 0.3% of the micro-nano fibers in the silicate solution to form an aqueous plugging and profile control system solution;

[0060] S3: Add 1.5% of the cross-linking agent to the aqueous plugging and profile control system solution, stir until completely dissolved, and a milky white gel can be formed after 3 hours at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0061] Example 4:

[0062] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, comprising the following steps:

[0063] S1: Dissolve 2% of the silicate main agent and 0.2% of the auxiliary agent in water, and stir until completely dissolved to form a silicate solution;

[0064] S2: Disperse 0.3% of the micro-nano fibers in the silicate solution to form an aqueous plugging and profile control system solution;

[0065] S3: Add 1% of the cross-linking agent to the aqueous plugging and profile control system solution, stir until completely dissolved, and a milky white gel can be formed after 2 hours at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0066] Example 5:

[0067] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, comprising the following steps:

[0068] S1: Dissolve 2% of the silicate main agent in water, and stir until completely dissolved to form a silicate solution;

[0069] S2: Disperse 0.1% of the micro-nano fibers in the silicate solution to form an aqueous plugging and profile control system solution;

[0070] S3: Add 1% of the cross-linking agent to the aqueous plugging and profile control system solution, stir until completely dissolved, and a milky white gel can be formed after 1 hour at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0071] Example 6:

[0072] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, comprising the following steps:

[0073] S1: Dissolve 2% of the silicate main agent and 0.2% of the auxiliary agent in water, and stir until completely dissolved to form a silicate solution;

[0074] S2: Disperse 0.2% of the micro-nano fibers in the silicate solution to form an aqueous plugging and profile control system solution;

[0075] S3: Add 1% crosslinking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and a milky white gel can be formed after 2 h at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0076] Example 7:

[0077] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent includes the following steps:

[0078] S1: Dissolve 3% silicate main agent in water, stir until completely dissolved to form a silicate solution;

[0079] S2: Disperse 0.3% micro-nano fibers in the silicate solution to form an aqueous solution of the plugging and profile control system;

[0080] S3: Add 1.5% crosslinking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and a milky white gel can be formed after 1 h at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0081] Example 8:

[0082] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent includes the following steps:

[0083] S1: Dissolve 3% silicate main agent in water, stir until completely dissolved to form a silicate solution;

[0084] S2: Disperse 0.1% micro-nano fibers in the silicate solution to form an aqueous solution of the plugging and profile control system;

[0085] S3: Add 1.5% crosslinking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and a milky white gel can be formed after 1 h at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0086] Example 9:

[0087] A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent includes the following steps:

[0088] S1: Dissolve 3% silicate main agent and 0.2% auxiliary agent in water, stir until completely dissolved to form a silicate solution;

[0089] S2: Disperse 0.3% micro-nano fibers in the silicate solution to form an aqueous solution of the plugging and profile control system;

[0090] S3: Add 1.5% crosslinking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and a milky white gel can be formed after 2 h at room temperature to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

[0091] The fiber-reinforced inorganic gels prepared in Example 1, Example 2, Example 3, and Example 4 were tested using a rheometer:

[0092] The stress τ was fixed at 0.5 Pa, and the frequency f was changed from 0.1 Hz to 1 Hz; see Figure 2 , Figure 3 , which are the G′ and G″ diagrams of the fiber-reinforced inorganic gels with different concentrations and 5% conventional inorganic gels under different f conditions of the present invention;

[0093] The frequency f was fixed at 1 Hz, and the stress τ was changed from 0 Pa to 20 Pa; see Figure 4 , Figure 5 , which are the G′ and G″ diagrams of the fiber-reinforced inorganic gels with different concentrations under different stress conditions of the present invention;

[0094] For the fiber-reinforced inorganic gel plugging agent, G′ is greater than G″. When the concentration of the main agent of the gel increases and the cross-linking agent increases, both G′ and G″ increase accordingly. The G′ and G″ of the fiber-reinforced inorganic gel are much higher than those of the 5% conventional inorganic gel. Experimental verification shows that after 180 days of retention, the fiber-reinforced inorganic gel is still a solid gel.

[0095] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A fiber-reinforced inorganic gel plugging and profile control agent, characterized in that, the raw material composition includes 1% - 5% by mass of a silicic acid main agent, 0.1% - 5% of a crosslinking agent, 0.1% - 0.3% of micro-nano fibers, and 0% - 0.5% of an auxiliary agent, and the rest is water.

2. The fiber-reinforced inorganic gel plugging and profile control agent according to claim 1, characterized in that, the silicic acid main agent is sodium silicate or sodium metasilicate.

3. A preparation method of a fiber-reinforced inorganic gel plugging and profile control agent, characterized in that, it includes the following steps: Dissolve 1% - 5% of the silicic acid main agent and 0% - 0.5% of the auxiliary agent in water, and stir until completely dissolved to form a silicate solution; Disperse 0.1% - 0.3% of the micro-nano fibers in the silicate solution to form an aqueous solution of a plugging and profile control system; Add 0.1% - 5% of the crosslinking agent to the aqueous solution of the plugging and profile control system, stir until completely dissolved, and let it stand to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

4. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 3, characterized in that, the silicic acid main agent is sodium silicate or sodium metasilicate.

5. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 3, characterized in that, the crosslinking agent is at least one of magnesium sulfate, magnesium chloride, and calcium chloride.

6. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 3, characterized in that, the auxiliary agent is a mixture of nitrilotriacetic acid and diethylenetriaminepentaacetic acid.

7. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 6, characterized in that, the mixing mass ratio of the nitrilotriacetic acid to the diethylenetriaminepentaacetic acid is 2:

1.

8. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 3, characterized in that, after adding 0.1% - 5% of the crosslinking agent and stirring until completely dissolved, a white solution is formed, and it is left to stand at a set temperature and for a set time to obtain an inorganic gel plugging and profile control agent with a three-dimensional network structure.

9. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 8, characterized in that, the set temperature is from room temperature to 180°C.

10. The preparation method of a fiber-reinforced inorganic gel plugging and profile control agent according to claim 8, characterized in that, the set time is 1 - 6 h.

Images