CN113337266B - Fracturing fluid system for enhancing pressure bearing capacity of proppant and application method thereof - Google Patents

Abstract

The invention discloses a fracturing fluid system for enhancing the bearing capacity of a proppant, which comprises a fracturing fluid and a modified proppant; the fracturing fluid comprises a base fluid and a reinforcing component, wherein the reinforcing component is one or a compound of at least two of phenyl methacrylate, p-chlorophenyl methacrylate, N-phenyl acrylamide, acryloyl imidazole, N-methylene bisacrylamide, divinylbenzene, 1, 3-bis (1-methylvinyl) benzene, azobisisobutyronitrile, benzoyl peroxide, dicumyl peroxide and di-tert-butyl peroxide. The modified proppant is one of gamma- (methacryloyloxy) propyl trimethoxy silane, vinyl-tri (2-methoxyethoxy) silane, etc. The fracturing fluid reinforcing component can be spontaneously adsorbed and spread on the surface of the modified propping agent to form a tough film coating layer, and the film coating layer can improve the oleophylic property of the propping agent, enhance the oil gas flow conductivity and improve the oil gas yield.

Description

Fracturing fluid system for enhancing pressure bearing capacity of proppant and application method thereof

Technical Field

The invention relates to the technical field of oil and gas exploitation, in particular to a fracturing fluid for enhancing the pressure bearing capacity of a fracturing propping agent and a using method thereof.

Background

The hydraulic fracturing technology is used as a main measure for increasing the yield of an oil-gas well and increasing the injection of a water well, is widely applied to the development of low-permeability/ultra-low-permeability oil-gas fields, and is one of the most important measures for increasing and stabilizing the yield of the oil-gas fields. The hydraulic fracturing process is to pump a high-viscosity pad fluid into a target reservoir to enable the formation to form an extended fracture at a high pressure exceeding the fracture pressure of the formation; then injecting a sand-carrying fluid mixed with a proppant into the formed fracture so that the proppant is spread in the fracture; and finally, breaking the sand carrying fluid to reduce the viscosity of the fluid into low-viscosity fluid, and flowing to the shaft to be discharged to the ground. By the technology, a flow channel with high conductivity formed by propping the fracture wall surface with proppant is left in the stratum, so that oil and gas can flow from a far well stratum to the bottom of a well.

After the hydraulic fracturing construction is completed, the flow conductivity of the artificial fracture is an important parameter for evaluating whether the construction is successful or not, and is mainly influenced by the laying efficiency of the propping agent and the propping capacity of the propping agent. Wherein, the laying efficiency is controlled by the construction process, and the pressure bearing capacity is determined by the material. As oil and gas resources are developed to deeper strata, the requirements on the proppant are improved, and higher requirements are put forward on the performance of the proppant, particularly the compressive strength. Compared with the quartz sand proppant which is low in price and wide in source, in order to meet the requirement of improving the pressure resistance, a film-coated proppant or a ceramsite proppant has to be adopted, and the latter two proppants are much higher in price than the quartz sand proppant due to the complex preparation process. In addition, the conventional ceramsite proppant is generally high in density and poor in portability; if the density is reduced, the price of the ceramsite proppant can be further greatly increased.

Therefore, under the background of large-scale popularization of the current hydraulic fracturing technology, the technology with strong bearing capacity, low price and simple operation can be simultaneously met, and great assistance is provided for the development of oil and gas energy in China.

Disclosure of Invention

The invention aims to provide a fracturing fluid system capable of enhancing the bearing capacity of a propping agent and a using method of the fracturing fluid system aiming at the defects of the existing propping agent for fracturing.

The fracturing fluid system for enhancing the pressure bearing capacity of the proppant comprises fracturing fluid and a modified proppant.

The fracturing fluid comprises a base fluid and a reinforcing component, wherein the reinforcing component is one or a compound of at least two of phenyl methacrylate, p-chlorophenyl methacrylate, N-phenylacrylamide, acryloyl imidazole, N-methylenebisacrylamide, divinylbenzene, 1, 3-bis (1-methylvinyl) benzene, azobisisobutyronitrile, benzoyl peroxide, dicumyl peroxide and di-tert-butyl peroxide.

The base liquid of the fracturing fluid contains conventional components, wherein the conventional components are selected from one or more of guar gum, hydroxypropyl guar gum, hydroxyethyl cellulose, anionic polyacrylamide, polyvinyl alcohol, polyethylene glycol, glutaraldehyde, dodecyl dimethyl benzyl ammonium chloride, tetramethyl ammonium chloride, potassium chloride, ammonium chloride, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, alpha-olefin sodium sulfonate, cocamido hydroxysulfobetaine, lauramidopropyl betaine and dodecyl glucoside.

The weight ratio of the reinforcing component to the base fluid in the fracturing fluid is 0.1-10 parts: 90-99.9 parts; the preferred ratio is 1:99. the weight parts of the reinforcing component and the base fluid are 100 parts in total.

The modified proppant is a conventional proppant that has been surface modified with a modifier. The conventional propping agent can be desert sand and conventional quartz sand with poor bearing capacity, and can also be precoated sand, ceramsite and steel slag with strong bearing capacity. The modifier is one or more of gamma- (methacryloyloxy) propyl trimethoxy silane, vinyl-tri (2-methoxyethoxy) silane and vinyl triethoxy silane.

The modified proppant is prepared by the following method: adding the conventional proppant into an ethanol solution containing the modifier, uniformly stirring, standing, fully wetting the surface of the conventional proppant, filtering, and drying to obtain the modified proppant.

The use method of the fracturing fluid system for enhancing the pressure bearing capacity of the proppant comprises the following steps:

(1) Respectively preparing base liquid and reinforcing components on the ground;

(2) Mixing the prepared base fluid, the reinforcing component and the modified propping agent, and uniformly stirring at a high speed to form a sand-carrying fluid;

(3) Conveying the sand-carrying liquid into artificial cracks through a hydraulic fracturing truck;

(4) Closing the well and stabilizing for 20-120 minutes after the sand is added;

(5) And opening the well mouth and discharging the fracturing fluid back.

Under formation conditions, the reinforcing component in the fracturing fluid can be combined with the modified proppant to improve the bearing capacity of the original proppant through covalent bonds or non-covalent bonds. The reinforcing component can be spontaneously adsorbed and spread on the surface of the modified proppant, and a coating layer with toughness is formed on the surface of the proppant along with the increase of the temperature. The film coating layer can increase the contact area between the proppants and prevent the proppants from being broken under the stratum closing pressure. Meanwhile, the film coating layer can improve the oleophylic performance of the propping agent and enhance the oil-gas flow conductivity.

The fracturing fluid has the power transmission and the proppant carrying energy efficiency of common fracturing fluid, and can enhance the pressure bearing capacity of the proppant, improve the pressure bearing capacity of the proppant with the original breaking rate which cannot meet the construction requirement, support artificial cracks, maintain a high-permeability diversion channel and improve the exploitation efficiency of oil and gas fields.

Compared with the prior art, the invention has the advantages that:

(1) The fracturing fluid can enhance the bearing capacity of the fracturing propping agent and improve the application range of the existing cheap propping agent product.

(2) The pressure-bearing capacity of the enhanced fracturing propping agent can reach or even exceed that of a corresponding film-coated propping agent, but the propping agent does not need a film coating process, so that the corresponding cost of the film-coated propping agent is saved.

(3) The enhanced fracturing propping agent can effectively enhance the interaction among different propping agent particles, prevent the flowback of fracturing fluid and the sand production phenomenon in the production process, and reduce the risk of the pipeline being abraded by the propping agent.

(4) The fracturing fluid for enhancing the bearing capacity of the proppant has simple preparation, does not need to add additional equipment and does not increase the construction cost.

(5) The reinforcing component can be spontaneously adsorbed and spread on the surface of the modified propping agent to form a tough film coating layer, and the film coating layer can improve the oleophylic property of the propping agent, enhance the oil-gas flow conductivity, improve the oil-gas yield and increase the economic benefit.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic diagram of the operation of the fracturing fluid system of the present invention to enhance the bearing capacity of proppant.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

The working principle of the fracturing fluid system for enhancing the bearing capacity of the proppant is shown in figure 1. First stage (surface and wellbore): the base fluid, the reinforcing component and the modified propping agent of the fracturing fluid are put into the same container, stirred at a high speed and dispersed uniformly to obtain the sand-carrying fluid, and then the sand-carrying fluid is pumped underground by a fracturing pump truck, and the reinforcing component is uniformly dispersed in the system in the form of small liquid drops at this stage. In the second stage (in the fracture), along with the entry of the sand-carrying fluid into each level of fracture of the stratum, the modified propping agent is gradually settled and piled up under the influence of gravity, a large number of gaps are formed among the particles, and reinforcing components can be filled in the gaps. And in the third stage (closing the well), the well is closed for a period of time along with the completion of fracturing construction, at the moment, the reinforcing component is adsorbed and spread on the surface of the modified proppant, and a layer of coating film is formed on the surface of the proppant through covalent bonds or non-covalent bonds along with the rise of temperature, so that the pressure resistance of the proppant is enhanced.

Example 1

A preparation method of surface modified quartz sand comprises the following steps:

(1) Weighing 2 parts of gamma- (methacryloyloxy) propyl trimethoxy silane, 1 part of vinyl trimethoxy silane and 300 parts of ethanol, adding into a container, stirring and mixing uniformly to obtain a mixed solution A, and storing at 5-25 ℃ for later use.

(2) Weighing 100 parts of dry 20/40-mesh conventional quartz sand and 20 parts of mixed liquor A, adding into a container, uniformly stirring, standing for 5min, and fully wetting the surface of the quartz sand by the mixed liquor A to obtain a mixture B.

(3) And transferring the mixture B into an oven at 90 ℃, and drying for 60min to obtain the surface modified quartz sand proppant.

Example 2

A preparation method of surface modified desert sand comprises the following steps:

(1) Weighing 2 parts of gamma- (methacryloyloxy) propyl trimethoxy silane, 1 part of vinyl-tri (2-methoxyethoxy) silane and 300 parts of ethanol, adding into a container, stirring and mixing uniformly to obtain a mixed solution A, and storing at the temperature of 5-25 ℃ for later use.

(2) Weighing 100 parts of dry 40/70-mesh conventional desert sand and 20 parts of mixed liquor A, adding into a container, uniformly stirring, standing for 5min, and fully wetting the surface of quartz sand by the mixed liquor A to obtain a mixture B.

(3) And transferring the mixture B into an oven at 80 ℃, and drying for 90min to obtain the surface modified desert sand proppant.

Example 3

A preparation method of surface modified ceramsite comprises the following steps:

(1) Weighing 2 parts of gamma- (methacryloyloxy) propyl trimethoxy silane, 1 part of vinyl triethoxy silane and 300 parts of ethanol, adding into a container, stirring and mixing uniformly to obtain a mixed solution A, and storing at 5-25 ℃ for later use.

(2) Weighing 150 parts of dried 40/70-mesh ceramsite and 20 parts of the mixed solution A, adding into a container, uniformly stirring, standing for 5min, and fully wetting the surface of quartz sand by the mixed solution A to obtain a mixture B.

(3) And transferring the mixture B into a 100 ℃ oven, and drying for 30min to obtain the surface modified ceramsite proppant.

Example 4

The implementation effect of the fracturing fluid system for enhancing the bearing capacity of the proppant comprises the following steps:

(1) Weighing 100 parts of phenyl methacrylate, 20 parts of N-phenylacrylamide, 3 parts of N, N-methylenebisacrylamide, 1.5 parts of azobisisobutyronitrile and 1.5 parts of benzoyl peroxide in a container, stirring and mixing uniformly to obtain a mixed solution A which is an enhanced component, and storing at 0-5 ℃ for later use.

(2) Weighing 1 part of guar gum, 0.5 part of polyvinyl alcohol, 0.5 part of dodecyl dimethyl benzyl ammonium chloride, 1 part of tetramethylammonium chloride, 0.5 part of sodium dodecyl sulfonate and 0.5 part of cocoamido hydroxy sulfobetaine in a container, adding 100 parts of water, stirring and mixing uniformly to obtain a mixed solution B, namely a base solution, and storing at 5-25 ℃ for later use.

(3) And weighing 0.5 part of the mixed solution A, 99.5 parts of the mixed solution B and 30 parts of the modified quartz sand proppant prepared in the example 1 into a container, and uniformly stirring and mixing to obtain a mixture C, namely the sand-carrying liquid.

(4) Transferring the mixture C into an oven at 60 ℃, standing for 120min, filtering to obtain solid particles, and cleaning with tap water.

(5) And (3) drying the solid particles in an oven at 105 ℃ for 30min to obtain the quartz sand proppant D.

(6) The silica sand proppant D and the initial unmodified 20/40 mesh silica sand of example 1 were taken and the breakage rate was measured at 35MPa, with the results shown in Table 1.

TABLE 1 breakage rate of 20/40 mesh Quartz Sand and Quartz Sand proppant D

Proppant	20/40 mesh quartz sand	Quartz sand proppant D
			Rate of breakage	14.8％	5.2％

As can be seen from the data in Table 1, the pressure bearing capacity of the quartz sand proppant D enhanced by the fracturing fluid is obviously higher than that of common quartz sand.

Example 5

The implementation effect of the fracturing fluid system for enhancing the bearing capacity of the proppant comprises the following steps:

(1) Weighing 100 parts of phenyl methacrylate, 10 parts of chlorophenyl methacrylate, 5 parts of divinylbenzene, 1.5 parts of azobisisobutyronitrile and 1.5 parts of dicumyl peroxide, stirring and mixing uniformly in a container to obtain a mixed solution A which is the reinforcing component, and storing at 0-5 ℃ for later use.

(2) Weighing 1 part of hydroxypropyl guar gum, 0.5 part of polyethylene glycol, 0.5 part of dodecyl dimethyl benzyl ammonium chloride, 1 part of potassium chloride, 0.5 part of sodium dodecyl benzene sulfonate and 0.5 part of lauramidopropyl betaine, adding 100 parts of pure water into a container, stirring and mixing uniformly to obtain a mixed solution B, namely a base solution, and storing at 5-25 ℃ for later use.

(3) Weighing 1 part of the mixed solution A, 99 parts of the mixed solution B and 30 parts of the modified desert sand proppant prepared in the example 2, and uniformly stirring and mixing the mixture in a container to obtain a mixture C.

(4) Transferring the mixture C into an oven at 90 ℃, standing for 60min, filtering to obtain solid particles, and cleaning with tap water.

(5) And (3) drying the solid particles in a drying oven at 105 ℃ for 30min to obtain the desert sand proppant D.

(6) The unmodified 40/70 mesh desert sand and the homemade desert sand proppant D described in example 2 were taken and the percent crush was determined at 35MPa and the results are shown in Table 2.

TABLE 2, 40/70 mesh desert sand and self-made desert sand proppant D

Proppant	20/40 mesh desert sand	Desert sand proppant D
			Rate of breakage	28.4％	11.3％

As can be seen from the data in Table 2, the pressure bearing capacity of the desert sand proppant D enhanced by the fracturing fluid is obviously higher than that of common desert sand.

Example 6

A fracturing fluid implementation effect for enhancing the pressure bearing capacity of a propping agent comprises the following steps:

(1) Weighing 100 parts of phenyl methacrylate, 25 parts of acryloyl imidazole, 3 parts of 1, 3-bis (1-methylvinyl) benzene, 1.5 parts of azobisisobutyronitrile and 1.5 parts of benzoyl peroxide, uniformly stirring and mixing in a container to obtain a mixed solution A, namely an enhanced component, and storing at 0-5 ℃ for later use.

(2) Weighing 0.1 part of anionic polyacrylamide, 0.5 part of polyvinyl alcohol, 0.5 part of dodecyl dimethyl benzyl ammonium chloride, 1 part of ammonium chloride, 0.5 part of alpha-olefin sodium sulfonate (dodecane) and 0.5 part of dodecyl glucoside, adding 100 parts of pure water into a container, stirring and mixing uniformly to obtain a mixed solution B, namely a base solution, and storing at 5-25 ℃ for later use.

(3) And weighing 0.5 part of the mixed solution A, 99.5 parts of the mixed solution B and 30 parts of the modified ceramsite proppant prepared in the example 3, and uniformly stirring and mixing the materials in a container to obtain a mixture C.

(4) Transferring the mixture C into a 120 ℃ oven, standing for 30min, filtering to obtain solid particles, and cleaning with tap water.

(5) And (3) drying the solid particles in an oven at 105 ℃ for 30min to obtain the ceramsite proppant D.

(6) The unmodified 40/70 mesh ceramic particles and ceramic particle propping agent D described in example 3 were taken, and the breaking rate was measured at 70MPa, and the results are shown in Table 3.

TABLE 3 breakage rate of 20/40 mesh ceramsite and self-made ceramsite proppant D

Proppant	20/40 mesh ceramsite	Ceramsite proppant D
			Rate of breakage	3.2％	2.2％

As can be seen from the data in Table 3, the pressure-bearing capacity of the ceramsite proppant D enhanced by the fracturing fluid is obviously higher than that of common ceramsite.

Although the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention.

Claims (7)

1. A fracturing fluid system for enhancing the bearing capacity of a propping agent is characterized by comprising a fracturing fluid and a modified propping agent;

the fracturing fluid comprises base fluid and a reinforcing component, wherein the reinforcing component is formed by combining three types of raw materials and comprises a polymerizable monomer, a cross-linking agent and an initiator; the polymerizable monomer is one or the composition of at least two of phenyl methacrylate, p-chlorophenyl methacrylate, N-phenyl acrylamide and acryloyl imidazole; the cross-linking agent is one or the composition of at least two of N, N-methylene bisacrylamide, divinylbenzene and 1, 3-di (1-methylvinyl) benzene; the initiator is one or the composition of at least two of azodiisobutyronitrile, benzoyl peroxide, dicumyl peroxide and ditert-butyl peroxide;

the modified proppant is a conventional proppant subjected to surface modification by a modifier, and the modifier is one or a plurality of compounds of gamma- (methacryloyloxy) propyl trimethoxy silane, vinyl-tri (2-methoxyethoxy) silane and vinyl triethoxy silane.

2. The fracturing fluid system for enhancing the bearing capacity of the proppant as set forth in claim 1, wherein the conventional proppant is one of desert sand, quartz sand, precoated sand, ceramsite and steel slag.

3. The fracturing fluid system of claim 2, wherein the modified proppant is made by a method comprising: adding the conventional proppant into an ethanol solution containing the modifier, uniformly stirring, standing, fully wetting the surface of the conventional proppant, filtering, and drying to obtain the modified proppant.

4. A fracturing fluid system for enhancing the pressure bearing capacity of a proppant as set forth in claim 1, wherein said base fluid comprises conventional components selected from one or more of guar, hydroxypropyl guar, hydroxyethyl cellulose, anionic polyacrylamide, polyvinyl alcohol, polyethylene glycol, glutaraldehyde, dodecyl dimethyl benzyl ammonium chloride, tetramethyl ammonium chloride, potassium chloride, ammonium chloride, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium alpha olefin sulfonate, cocamido hydroxysulfobetaine, lauramidopropyl betaine, dodecyl glycoside.

5. The fracturing fluid system for enhancing the bearing capacity of the proppant as set forth in claim 4, wherein the amount of the reinforcing component and the base fluid in the fracturing fluid is 0.1-10 parts by weight: 90-99.9 parts; the weight parts of the reinforcing component and the base fluid are 100 parts in total.

6. The use method of the fracturing fluid system for enhancing the bearing capacity of the propping agent as recited in any of claims 1 to 5, characterized in that a base fluid and a reinforcing component are respectively prepared on the ground, and the base fluid, the reinforcing component and the modified propping agent are uniformly mixed to form a sand-carrying fluid; then conveying the sand-carrying liquid into the artificial cracks, and closing the well for stabilizing for 20-120 minutes after the sand is added; and finally opening the well mouth and discharging the fracturing fluid back.

7. The method of using a fracturing fluid system with enhanced proppant containment capability of claim 6, comprising the steps of:

(1) Respectively preparing base liquid and reinforcing components on the ground;

(2) Mixing the prepared base fluid, the reinforcing component and the modified propping agent, and uniformly stirring at a high speed to form a sand-carrying fluid;

(3) Conveying the sand-carrying liquid into artificial cracks through a hydraulic fracturing truck;

(4) Closing the well and stabilizing for 20-120 minutes after the sand is added;

(5) And opening the well mouth and discharging the fracturing fluid back.

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