阅读说明：本技术 一种气固液三相压裂液体系及其使用方法 (Gas-solid-liquid three-phase fracturing fluid system and using method thereof ) 是由 杨波 张�浩 杨洋 钟颖 杨荻 范峥 于 2021-09-02 设计创作，主要内容包括：本发明公开了一种气固液三相压裂液体系及其使用方法,涉及油气开发技术领域。本发明公开的压裂液体系,包括以质量份数计的以下组分：水溶性疏水缔合聚合物0.05～2份、支撑剂1～70份、气相0.01～10份、起泡剂0.001～5份、溶剂100份,其中,支撑剂为具有表面疏水性的疏水类支撑剂；所述溶剂为水。本发明还公开了一种压裂液体系的使用方法。本发明提供一种气固液三相压裂液体系,采用气固液三相相互作用力来增加气固液三相压裂液体系对支撑剂的携带能力,得到携砂能力强、对储层伤害小的气固液三相压裂液体系。(The invention discloses a gas-solid-liquid three-phase fracturing fluid system and a using method thereof, and relates to the technical field of oil-gas development. The invention discloses a fracturing fluid system which comprises the following components in parts by weight: 0.05-2 parts of water-soluble hydrophobic association polymer, 1-70 parts of propping agent, 0.01-10 parts of gas phase, 0.001-5 parts of foaming agent and 100 parts of solvent, wherein the propping agent is hydrophobic propping agent with surface hydrophobicity; the solvent is water. The invention also discloses a use method of the fracturing fluid system. The invention provides a gas-solid-liquid three-phase fracturing fluid system, which adopts gas-solid-liquid three-phase interaction force to increase the carrying capacity of the gas-solid-liquid three-phase fracturing fluid system on a propping agent, and obtains the gas-solid-liquid three-phase fracturing fluid system with strong sand carrying capacity and little damage to a reservoir.)

1. The gas-solid-liquid three-phase fracturing fluid system is characterized by comprising the following components in parts by mass:

wherein the proppant is a hydrophobic proppant with surface hydrophobicity; the solvent is water.

2. The gas-solid-liquid three-phase fracturing fluid system of claim 1, wherein the water-soluble hydrophobically associative polymer is any one or more of hydrophobically modified acrylamide polymers.

3. The gas-solid-liquid three-phase fracturing fluid system of claim 1, wherein the hydrophobic proppant is a proppant with a natural hydrophobic surface or a proppant with a hydrophobic resin film coated on the surface or a proppant with a hydrophobic chain on the surface.

4. The gas-solid-liquid three-phase fracturing fluid system of claim 3, wherein the hydrophobic proppant is a hydrophobically modified ceramsite or hydrophobically modified quartz sand.

5. The gas-solid-liquid three-phase fracturing fluid system of claim 1, wherein the gas phase is one or more of nitrogen, air, methane and carbon dioxide.

6. The gas-solid-liquid three-phase fracturing fluid system of claim 1, wherein the solvent is any one of clear water, water containing mineral salts or oil well flowback water.

7. The use method of the gas-solid-liquid three-phase fracturing fluid system is characterized by comprising the following steps: the gas-liquid-solid-liquid three-phase fracturing fluid system formulation of any one of claims 1 to 7, which specifically comprises:

(1) slowly adding a water-soluble hydrophobic association polymer and a foaming agent into a solvent, and stirring to completely dissolve the water-soluble hydrophobic association polymer and the foaming agent to obtain fracturing fluid;

(2) adding a propping agent into the fracturing fluid, injecting the fracturing fluid into an oil well/gas well under a stirring state, and simultaneously injecting a gas phase, so that the gas phase, the propping agent and the fracturing fluid are fully mixed in a ground pump injection pipeline and a shaft to form a fracturing fluid system.

8. Use according to claim 7, characterized in that when the gaseous phase is nitrogen, liquid nitrogen injection is used.

9. The use of claim 7, wherein the proppant is mixed with the fracturing fluid by a frac truck and injected into the frac well.

Technical Field

The invention relates to the technical field of oil-gas development, in particular to a gas-solid-liquid three-phase fracturing liquid system and a using method thereof.

Background

Fracturing is the main measure for increasing the production of the low-permeability oil and gas reservoirs at present. The fracturing is that a pre-positioned fluid is injected by a high-pressure pump to form cracks on a stratum, then a sand-carrying fluid carrying propping agent such as ceramsite, quartz sand and the like is pumped in to fill the cracks, and the cracks are prevented from being closed under the stress of the stratum after the pump is stopped, so that the cracks with high permeability are formed. Therefore, the carrying capacity of the sand-carrying fluid on the proppant particles has been the key of research.

Much of the previous research has focused on how to increase the viscoelastic properties of fracturing fluids, such as highly viscous crosslinked guar gums, crosslinked polyacrylamide polymers, etc., in the subsurface, and such techniques have matured considerably over decades. However, the high-viscosity fluid usually has great damage to the current low-permeability reservoir, and a great deal of research shows that the fracturing fluid is difficult to adapt to the fracturing of low-permeability and ultra-low-permeability sandstone and shale at present and shows poor construction effect in actual construction.

In contrast, low-viscosity, low-damage slickwater fracturing has proven to be more amenable to fracturing reformation in low-permeability hydrocarbon reservoirs and has led to great success in shale hydrocarbon development. The slickwater with low viscosity and low damage better keeps the permeability of the stratum and the flow conductivity of the paved crack, and ensures the smoothness of the gas migration path. Thereby establishing an unblocked flow network channel of oil and gas among the artificial fractures, the natural fractures and the matrix pores. However, slickwater has a poor ability to carry proppant and requires high pump speeds and large volumes of water to carry sufficient proppant into the formation. The concentration of the proppant is usually only 30-120 kg/m³The pumping speed usually reaches or even exceeds 20m³And/min, the water consumption of a single well is 1-5 ten thousand in general. The construction method has obvious disadvantages that a large amount of large-scale pumping equipment is required for high pumping speed, so that the fracturing cost is high, and the water consumption is highBut also causes great pressure on the environment and ecology, and is difficult to develop continuously. Another way is to reduce the density of the proppant so that it is easier to carry, such as making hollow-core ceramsite, low-density resin proppant, expanded polymer-encased proppant, etc., but these are often too costly or too harmful to the formation to be widely used.

The methods improve the sand carrying capacity of the fracturing fluid by singly relying on the viscoelasticity of the sand carrying fluid, singly relying on the capacity of lifting equipment or singly reducing the density of a propping agent, and have great disadvantages when the fracturing of a low-permeability reservoir is dealt with. The sand carrying process of the fracturing fluid is actually the result of the interaction of multiphase substances, the interaction force among various substances is increased, and the carrying efficiency of the propping agent can be improved. In patent CN201911035692.2 air suspending agent for fracturing propping agent and construction method thereof, a gas suspending fracturing propping agent is developed by spraying a hydrophobic adsorbable collector on the surface of the propping agent; the patent CN202011562454.X air bag shell inflation suspension proppant and its preparation method, the patent CN201611170927.5 air suspension proppant for slickwater fracturing and its preparation method and use method, and the patent CN201711418051.6 effervescent air suspension proppant for slickwater fracturing and its preparation method, all adopt the introduction of gas in fracturing, utilize the characteristic of gas adsorption on the surface of hydrophobic modified proppant, increase the molecular force of gas-solid two phase, reduce the overall density of proppant by adsorbing gas, and show good sand carrying capacity. However, these inventions neglect the important role of fracturing fluids, and only through gas-solid two-phase coupling, the suspension performance is reduced or even the effective suspension is not realized when the proppant particles with larger particles (such as 20/40 meshes) or larger density (such as ceramsite) are carried.

Disclosure of Invention

The application aims to solve the problems that in the prior art, fracturing fluid is high in damage to a reservoir due to sand carrying by viscosity and weak in suspension capacity of large-particle propping agents due to sand carrying by gas-solid two-phase coupling, and provides a gas-solid-liquid three-phase fracturing fluid system.

In order to achieve the above object, the present application provides the following technical solutions: a gas-solid-liquid three-phase fracturing fluid system comprises the following components in parts by mass:

wherein the proppant is a hydrophobic proppant with a hydrophobic surface; the solvent is water.

The gas-solid-liquid three-phase fracturing fluid system disclosed in the technical scheme is characterized in that a hydrophobic structure is introduced into molecules of a fracturing fluid thickening agent on the basis of gas-solid two-phase hydrophobic acting force, so that a self-aggregation network with three phases of hydrophobic propping agents (solid phase), gas (gas phase) and hydrophobic associated polymer fracturing fluid (liquid phase) is formed, the mutual aggregation acting force among all substances of the system is greatly increased, and the suspending force of the system on the propping agents is increased.

Further, the water-soluble hydrophobic association polymer is acrylamide association polymer, and can be selected from EM60, EM30, Guangya GAT-TP and the like of Changqing chemical group.

Further, the hydrophobic proppant is a proppant having a natural hydrophobic surface or a proppant having a surface coated with a hydrophobic resin film or a proppant having a hydrophobic carbon chain on the surface.

Further, the hydrophobic proppant is hydrophobic modified ceramsite or hydrophobic modified quartz sand, and preferably, the hydrophobic modified quartz sand is resin-coated quartz sand.

Further, the gas phase is one or more of nitrogen, air, methane and carbon dioxide, and preferably, when the gas phase is selected from nitrogen, liquid nitrogen is used for injection.

Further, the solvent is any one of clear water, water containing mineral salts or oil well flowback water.

Further, the fracturing fluid system comprises the following components in parts by mass:

the proppant is resin coated quartz sand.

The cross-linked gel system adopted in the traditional fracturing fluid system realizes the suspension of the proppant by utilizing the principle that the viscosity or viscoelasticity is used for carrying the proppant, so that the required amount of the associated polymer in the traditional fracturing fluid system is usually between 0.3 and 0.5 percent, and if the required amount is too low, the viscosity or viscoelasticity is too low, and the suspension of the proppant cannot be realized; too high of a catalyst tends to result in too high viscosity, affect the fluidity of the fracturing fluid system and cause difficulty in fracturing construction. According to the technical scheme, the suspension of the propping agent is realized by adopting the interaction force on the surface of the gas-solid-liquid three-phase hydrophobic material, so that the fracture supported by the fracturing is longer, and the propping agent is laid more uniformly in the longitudinal direction, thereby greatly increasing the yield of the oil-gas well after fracturing modification; meanwhile, the use amount of the polymer can be greatly reduced, and the cost is reduced.

The invention also discloses a use method of the fracturing fluid system, which adopts the formula of the gas-liquid-solid three-phase fracturing fluid system, and the specific use method comprises the following steps:

(1) slowly adding a water-soluble hydrophobic association polymer and a foaming agent into a solvent, and stirring to completely dissolve the water-soluble hydrophobic association polymer and the foaming agent to obtain fracturing fluid;

(2) adding a propping agent into fracturing fluid, stirring at a speed of 50-200 r/min on a sand mixing truck to form sand mixing fluid, pumping the sand mixing fluid into an oil well/gas well by using a high-pressure pump truck group, simultaneously injecting gas phase by using a high-pressure pump truck, and fully mixing the gas phase, the propping agent and the fracturing fluid in a ground pumping pipeline and a shaft to form a fracturing fluid system.

In the technical scheme, the mixed liquid of the gas phase, the propping agent and the fracturing liquid is pumped in by a high-pressure pump, and because the speed of the propping agent and the fracturing liquid in the pipe column is extremely high, usually at 300-2000 m/min, the gas phase, the propping agent and the fracturing liquid generate turbulence in a ground pump injection pipeline and a shaft, so that sufficient mixing is realized, and meanwhile, the gas phase is dispersed into fine micro bubbles and stably wrapped in a hydrophobic structure of the hydrophobically associating polymer. And due to the hydrophobicity of the air bubbles, the hydrophobicity of the propping agent and the hydrophobicity of the water-soluble hydrophobic association polymer, the three substances are aggregated due to the hydrophobic effect to generate interaction force. The air bubbles are adsorbed on the surface of the proppant and are wrapped by the hydrophobic structure of the hydrophobic association polymer to form a stable three-phase self-aggregation structure. In addition, the bubbles are adsorbed on the surface of the proppant, so that the volume density of proppant particles (attached bubbles) is greatly reduced, the suspension of the proppant is realized, the suspended particles are larger, and the sand carrying capacity of the system is stronger. The hydrophobic association polymer solution has good functions of wrapping bubbles and stabilizing foams. Therefore, the propping agent, the air bubbles and the fracturing fluid form a stable mixed system, the propping agent is stably suspended, the propping agent is favorably carried for a longer distance in a crack, and the propping agent is also more uniformly paved in the longitudinal direction.

Further, when the gas phase is nitrogen, liquid nitrogen injection is used.

Further, the proppant is injected into the fracturing fluid through a fracturing blender truck.

Compared with the prior art, the invention has the following beneficial effects:

the application discloses a gas-liquid-solid three-phase fracturing fluid system, which utilizes a gas-liquid-solid three-phase surface interaction force method to suspend a solid-phase particle proppant, fully considers the synergistic effect among different substances and greatly improves the performance. The theory of traditional viscosity or viscoelasticity for carrying the propping agent is broken. Compared with the traditional crosslinking glue system, the dosage of the water-soluble hydrophobic association polymer adopted by the system can be greatly reduced, the minimum dosage is only 0.05 percent, the dosage of the common crosslinking glue system polymer is usually 0.3 to 0.5 percent, and the dosage of the new system can be reduced to 1/6 to 1/10; the damage of the polymer to the oil and gas reservoir can be greatly reduced.

The gas-solid-liquid three-phase fracturing fluid system provided by the application has stronger sand carrying capacity, larger sand carrying amount and larger particle size of suspensible particles, and the sand carrying capacity of the gas-solid-liquid three-phase fracturing fluid system can reach 700kg/m³Compared with a slickwater system, the sand carrying capacity of the sand-removing device can be improved by more than 3.5 times; compared with air suspensionThe fracturing fluid system can stably carry 16/20-mesh and 20/40-mesh coarse ceramsite, and the carrying particle size is increased by more than 1 time.

The application method of the gas-solid-liquid three-phase fracturing fluid system can adopt lower water-soluble hydrophobic association polymer dosage, greatly increases sand carrying capacity, is beneficial to laying longer, more uniform and higher-conductivity cracks, and is beneficial to rapid flow of oil gas, thereby greatly increasing the yield of oil gas wells. In addition, the fracturing fluid system is simple to prepare, convenient to construct on site, wide in application range and beneficial to popularization and application.

Drawings

Fig. 1, a diagram of proppant suspension effectiveness of example 1 of the present disclosure.

Fig. 2, a diagram of proppant suspension effectiveness of example 2 of the present disclosure.

Detailed Description

The present invention will be described in further detail with reference to test examples and specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.

In the prior art, the fracturing propping agent is suspended by a polymer with high speed generated by large displacement or viscosity so as to achieve the purpose of carrying sand, but the two methods are difficult to achieve good carrying effect on propping agent particles with larger carrying particles and higher density.

In order to solve the technical problems, the inventor provides a three-phase fracturing fluid system, which adopts hydrophobic bubbles and hydrophobic association polymer formed in a gas phase to carry hydrophobic proppant particles to form a three-phase self-aggregation network of the fracturing fluid (liquid phase) containing the hydrophobic proppant (solid phase), gas (gas phase) and the hydrophobic association polymer, so that the interaction force among all substances in the fracturing fluid system is greatly increased, and the carrying effect on the proppant is provided. The present application is described in further detail below with specific examples.

In the following examples, the water-soluble hydrophobically associating polymer is a commercially available product, specifically GAF-TP manufactured by Sichuan photopolymer chemical Co., Ltd or EM60 manufactured by Changqing chemical group. The foaming agent is a non-ionic foaming agent or an ionic foaming agent which is sold in the market.

Example 1

In this embodiment, the fracturing fluid system comprises the following components in parts by mass:

wherein the particle size of the resin-coated quartz sand is 20-40 meshes.

The preparation method of the fracturing fluid system comprises the following steps:

0.01 part of sodium lauryl sulfate was added to 100 parts of clear water, slowly stirred to form a vortex, and then 0.1 part of GAF-TP was slowly added in such a manner as to prevent the GAF-TP from being hydrated into lumps. And after GAF-TP is fully dissolved, the GAF-TP is ready for use. Weighing 50 parts of the coated quartz sand proppant, pouring the coated quartz sand proppant into the solution, stirring at a high speed and introducing nitrogen. After 30s, the stirring was stopped and the proppant was observed to be suspended, as shown in fig. 1, with the proppant completely floating in the stirred cup.

Example 2

In this embodiment, the fracturing fluid system comprises the following components in parts by mass:

wherein the particle size of the hydrophobic modified ceramsite is 20-40 meshes. The blowing agent was purchased from ZX-3, all manufactured by Okinawa oil science and technology Ltd.

The preparation method of the fracturing fluid system comprises the following steps:

0.01 part of ZX-3 is added to 100 parts of clear water, slowly stirred to form a vortex, and then 0.1 part of EM60 is slowly added in the process of avoiding the EM60 from being hydrated into lumps. After EM60 is fully dissolved, the solution is ready for use. Weighing 50 parts of hydrophobic modified ceramsite, pouring the weighed 50 parts of hydrophobic modified ceramsite into the solution, stirring at a high speed and introducing nitrogen. After 30s, the stirring was stopped and the proppant was observed to be suspended, as shown in fig. 2, with the proppant completely floating in the stirred cup.

Comparative example 1

In this comparative example, the fracturing fluid system was prepared without the addition of a gas phase and a foaming agent, and the remaining components and preparation were essentially the same as in example 1.

Comparative example 2

In this comparative example, the fracturing fluid system used common quartz sand as proppant, and the remaining components and preparation method were essentially the same as in example 1.

Comparative example 3

In this comparative example, the fracturing fluid system employed a non-hydrophobic polyacrylamide drag reducer as the polymer, with the remaining components and preparation essentially the same as in example 1.

Comparative example 4

In this comparative example, the fracturing fluid system used common quartz sand as proppant, non-hydrophobic polyacrylamide drag reducer as polymer, and no gas phase and foaming agent were added, and the remaining components and preparation method were essentially the same as in example 1.

Comparative example 5

In this comparative example, the fracturing fluid system was prepared without the addition of a gas phase and a foaming agent, and the remaining components and preparation were essentially the same as in example 2.

Comparative example 6

In this comparative example, the fracturing fluid system used common ceramic particles as proppant, and the remaining components and preparation method were essentially the same as in example 2.

Comparative example 7

In this comparative example, the fracturing fluid system employed a non-hydrophobic polyacrylamide drag reducer as the polymer, with the remaining components and preparation essentially the same as in example 2.

Comparative example 8

In this comparative example, the fracturing fluid system used common ceramic particles as proppant, non-hydrophobic polyacrylamide drag reducer as polymer, and no gas phase and foaming agent were added, and the remaining components and preparation method were essentially the same as in example 2.

The fracturing fluid systems obtained in examples 1-2 and comparative examples 1-8 were measured for proppant sinking rate, and the measurement results are shown in table 1.

TABLE 1

The same conclusion is drawn by comparing the example 1 with the comparative examples 1-4 and comparing the example 2 with the comparative examples 5-8, and the suspension property of the proppant can be remarkably improved by adopting a gas-liquid-solid three-phase synergistic effect method. Only by adopting the synergistic effect of the liquid-solid two phases (such as comparative example 1 and comparative example 4), the liquid-gas two phases (such as comparative example 2 and comparative example 5) or the gas-solid two phases (such as comparative example 3 and comparative example 6), the proppant can not reach a full suspension state, and has a certain sinking speed. The suspension effects are ranked as follows: gas-liquid-solid > gas-solid > liquid-gas > liquid-solid > viscous sand carrying. Meanwhile, the effect of carrying sand by only utilizing the traditional viscosity is far lower than the effect of carrying sand by the cooperation of surface acting force. The gas-liquid-solid three-phase cooperation can achieve good suspension stability; secondly, gas-solid coordination shows that bubbles are adsorbed on the surface of the hydrophobic support surface, so that the density of the proppant can be reduced, and the sinking speed is greatly reduced; the liquid-gas synergy is beneficial to increasing the synergistic effect between the fracturing fluid and the proppant and reducing the sinking speed of the proppant to a certain degree because the liquid-phase retardation force is increased when the foam exists; and the conventional viscous sand carrier basically does not act on the surface of the proppant, so that the sinking speed is fastest.

In summary, the present invention provides a method and formulation for improving the suspension of a proppant by the synergistic effect of the surfaces of three phases, gas, liquid and solid, or two phases thereof. The invention breaks away from the theory that sand is carried by depending on viscosity or viscoelasticity all the time, and adopts the synergistic force of surface intermolecular interaction to carry the propping agent. The invention provides a new theory and a new method of a fracturing fluid system for suspending a proppant, which can replace the existing high-viscosity fracturing fluid system, solve the problems of weak sand carrying capacity and the like of the existing low-viscosity slickwater system, reduce the damage to a reservoir and improve the fracturing modification effect and the economic effect.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.