阅读说明：本技术 一种用于压裂增产措施的复合水基压裂液及其制备方法 (Composite water-based fracturing fluid for fracturing yield-increasing measures and preparation method thereof ) 是由 吴育煌 李江涛 于 2018-06-04 设计创作，主要内容包括：本发明涉及一种用于压裂增产措施的复合水基压裂液及其制备方法,该复合水基压裂液包含如下组分：聚乙烯醇和改性胍胶复合的增稠剂、复合有机硼交联剂、pH缓冲液、释酸性破胶剂和氧化性破胶剂复合的破胶剂和水。本发明的用于压裂增产措施的复合水基压裂液在保证压裂液造缝和携砂性能的前提下,通过优化压裂液配方,降低增稠剂的用量,减少残渣,降低压裂液成本,提高压裂液耐温、耐剪切性能,改善破胶性能,降低滤失量,降低压裂液对裂缝及储层的伤害程度,改善压裂效果,提高油田勘探开发效益,在保证压裂施工的同时,最大限度的保护储层和提高裂缝导流能力,降低压裂液的综合伤害。(The invention relates to a composite water-based fracturing fluid for fracturing stimulation measures and a preparation method thereof, wherein the composite water-based fracturing fluid comprises the following components: the gel breaker comprises a thickening agent compounded by polyvinyl alcohol and modified guanidine gum, a compound organic boron crosslinking agent, a pH buffer solution, a gel breaker compounded by an acid-releasing gel breaker and an oxidizing gel breaker and water. The composite water-based fracturing fluid for fracturing yield-increasing measures reduces the dosage of a thickening agent, reduces residues, reduces the cost of the fracturing fluid, improves the temperature resistance and the shearing resistance of the fracturing fluid, improves the gel breaking performance, reduces the filtration loss, reduces the damage degree of the fracturing fluid to cracks and reservoirs, improves the fracturing effect, improves the exploration and development benefits of oil fields, ensures the fracturing construction, protects the reservoirs to the greatest extent, improves the flow conductivity of the cracks and reduces the comprehensive damage of the fracturing fluid by optimizing the formula of the fracturing fluid on the premise of ensuring the fracture-making and sand-carrying performances of the fracturing fluid.)

1. A composite water-based fracturing fluid for fracture stimulation, which is characterized by comprising the following components: the composite gel breaker comprises a thickening agent compounded by polyvinyl alcohol and modified guanidine gum, a composite organic boron crosslinking agent, a pH buffer solution, a gel breaker compounded by an acid-releasing gel breaker and an oxidizing gel breaker and water;

Wherein the polyvinyl alcohol accounts for 1-2.5% of the total mass of the composite water-based fracturing fluid; the modified guanidine gum accounts for 0.08-0.25% of the total mass of the composite water-based fracturing fluid; the composite organic boron crosslinking agent accounts for 0.3 to 2 percent of the total mass of the composite water-based fracturing fluid; the pH buffer solution accounts for 0.2-0.3% of the total mass of the composite water-based fracturing fluid; the acid-releasing gel breaker accounts for 0.2-1% of the total mass of the composite water-based fracturing fluid; the percentage of the oxidizing gel breaker in the total mass of the composite water-based fracturing fluid is 0.01-0.06%; the balance being water.

2. The composite water-based fracturing fluid of claim 1, wherein the polyvinyl alcohol accounts for 1.5-2% of the total mass of the composite water-based fracturing fluid; the modified guanidine gum accounts for 0.12-0.18% of the total mass of the composite water-based fracturing fluid; the composite organic boron crosslinking agent accounts for 0.8-1.2% of the total mass of the composite water-based fracturing fluid; the pH buffer solution accounts for 0.22-0.28% of the total mass of the composite water-based fracturing fluid; the acid-releasing gel breaker accounts for 0.4-0.8% of the total mass of the composite water-based fracturing fluid; the percentage of the oxidizing gel breaker in the total mass of the composite water-based fracturing fluid is 0.02-0.04%; the balance being water.

3. The composite water-based fracturing fluid of claim 1 or 2, wherein the composite organoboron crosslinker comprises the following components: OB-II crosslinking agent, glycol, borax and water.

4. The composite water-based fracturing fluid of claim 3, wherein the composite organic boron crosslinking agent comprises the following components in percentage by mass: 60-80% of OB-II crosslinking agent, 6-10% of glycol, 3-6% of borax and the balance of water.

5. The composite water-based fracturing fluid of claim 4, wherein the composite organic boron crosslinking agent comprises the following components in percentage by mass: 65-75% of OB-II crosslinking agent, 6.5-8% of glycol, 5-6% of borax and the balance of water.

6. The composite water-based fracturing fluid of claim 1, wherein the polyvinyl alcohol is formed by polymerizing 1, 3-glycol structure, and the hydrolysis degree of the polyvinyl alcohol is more than 75%.

7. The composite water-based fracturing fluid of claim 1, wherein the pH buffer is NaOH solution.

8. The composite water-based fracturing fluid of claim 7, wherein the concentration of the NaOH solution is 1%.

9. The composite water-based fracturing fluid of claim 1, wherein the acid-releasing breaker is an acid-releasing organic ester; the oxidative breaker is ammonium persulfate.

10. A method of preparing the composite water-based fracturing fluid of any one of claims 1 to 9, comprising: uniformly stirring and mixing polyvinyl alcohol, modified guanidine gum, a composite organic boron crosslinking agent, a pH buffer solution, an acid-releasing gel breaker and an oxidizing gel breaker according to the mass percentage, adding water, and continuously stirring and mixing to obtain the composite water-based fracturing fluid.

Technical Field

The invention relates to the technical field of oil well exploitation, in particular to a composite water-based fracturing fluid for fracturing production increasing measures and a preparation method thereof.

Background

With the exploration and exploitation of conventional oil and gas reservoirs, the resource reserves of the conventional oil and gas are reduced year by year, and in order to ensure the supply of the oil and gas, oil and gas field workers look at the exploration and exploitation of the unconventional oil and gas reservoirs. Unconventional oil and gas reserves account for a large proportion of oil and gas resources, have low porosity and low permeability characteristics, and can be industrially exploited by a fracture acidizing stimulation means. The viscoelastic rheological property and low fluid loss of the current fracturing fluid technology on fracture formation and proppant delivery basically reach the relevant indexes of fracturing design, and the fracturing can be successfully carried out under complex field conditions. However, the water-based fracturing fluid can cause damage to a water-sensitive stratum, and fracturing fluid residues can also cause damage to a supporting fracture and the stratum, and particularly in fracturing modification of an unconventional low-permeability oil and gas reservoir, secondary damage caused by the fracturing fluid is often a main factor influencing the post-fracturing effect. According to the Darcy formula, under the condition that other conditions are not changed, the yield of the oil well is in direct proportion to the permeability of the oil layer. Therefore, the reduction of the damage of the fracturing fluid to the matrix permeability and the supporting fracture of the reservoir is an important premise for improving the fracturing yield-increasing effect of the low-permeability reservoir, and becomes one of important hot spots for the research of the fracturing fluid.

Disclosure of Invention

The invention aims to provide a composite water-based fracturing fluid for fracturing yield-increasing measures and a preparation method thereof, and solves the problem of secondary damage of a water-sensitive stratum caused by high consumption of the water-based fracturing fluid for achieving the effect in the prior art.

The technical scheme adopted by the invention for solving the technical problem is as follows: a composite water-based fracturing fluid for fracture stimulation, comprising the following components: the composite gel breaker comprises a thickening agent compounded by polyvinyl alcohol and modified guanidine gum, a composite organic boron crosslinking agent, a pH buffer solution, a gel breaker compounded by an acid-releasing gel breaker and an oxidizing gel breaker and water; wherein the polyvinyl alcohol accounts for 1-2.5% of the total mass of the composite water-based fracturing fluid; the modified guanidine gum accounts for 0.08-0.25% of the total mass of the composite water-based fracturing fluid; the composite organic boron crosslinking agent accounts for 0.3 to 2 percent of the total mass of the composite water-based fracturing fluid; the pH buffer solution accounts for 0.2-0.3% of the total mass of the composite water-based fracturing fluid; the acid-releasing gel breaker accounts for 0.2-1% of the total mass of the composite water-based fracturing fluid; the percentage of the oxidizing gel breaker in the total mass of the composite water-based fracturing fluid is 0.01-0.06%; the balance being water.

In the composite water-based fracturing fluid, the polyvinyl alcohol accounts for 1.5-2% of the total mass of the composite water-based fracturing fluid; the modified guanidine gum accounts for 0.12-0.18% of the total mass of the composite water-based fracturing fluid; the composite organic boron crosslinking agent accounts for 0.8-1.2% of the total mass of the composite water-based fracturing fluid; the pH buffer solution accounts for 0.22-0.28% of the total mass of the composite water-based fracturing fluid; the acid-releasing gel breaker accounts for 0.4-0.8% of the total mass of the composite water-based fracturing fluid; the percentage of the oxidizing gel breaker in the total mass of the composite water-based fracturing fluid is 0.02-0.04%; the balance being water.

In the composite water-based fracturing fluid of the invention, the composite organoboron crosslinking agent comprises the following components: OB-II crosslinking agent, glycol, borax and water.

In the composite water-based fracturing fluid, the composite organic boron crosslinking agent comprises the following components in percentage by mass: 60-80% of OB-II crosslinking agent, 6-10% of glycol, 3-6% of borax and the balance of water.

In the composite water-based fracturing fluid, the composite organic boron crosslinking agent comprises the following components in percentage by mass: 65-75% of OB-II crosslinking agent, 6.5-8% of glycol, 5-6% of borax and the balance of water.

In the composite water-based fracturing fluid, the polyvinyl alcohol is formed by polymerizing a 1, 3-glycol structure, and the hydrolysis degree of the polyvinyl alcohol is more than 75%.

in the composite water-based fracturing fluid of the invention, the pH buffer solution is NaOH solution.

In the composite water-based fracturing fluid, the concentration of the NaOH solution is 1%.

In the composite water-based fracturing fluid, the acid-releasing gel breaker is an acid-releasing organic ester; the oxidative breaker is ammonium persulfate.

The invention also provides a preparation method of the composite water-based fracturing fluid, which comprises the following steps: uniformly stirring and mixing polyvinyl alcohol, modified guanidine gum, a composite organic boron crosslinking agent, a pH buffer solution, an acid-releasing gel breaker and an oxidizing gel breaker according to the mass percentage, adding water, and continuously stirring and mixing to obtain the composite water-based fracturing fluid.

The composite water-based fracturing fluid for fracturing stimulation measures and the preparation method thereof have the following beneficial effects: the composite water-based fracturing fluid for fracturing yield-increasing measures reduces the dosage of a thickening agent, reduces residues, reduces the cost of the fracturing fluid, improves the temperature resistance and the shearing resistance of the fracturing fluid, improves the gel breaking performance, reduces the filtration loss, reduces the damage degree of the fracturing fluid to cracks and reservoirs, improves the fracturing effect, improves the exploration and development benefits of oil fields, ensures the fracturing construction, protects the reservoirs to the greatest extent, improves the flow conductivity of the cracks and reduces the comprehensive damage of the fracturing fluid by optimizing the formula of the fracturing fluid on the premise of ensuring the fracture-making and sand-carrying performances of the fracturing fluid.

Detailed Description

The composite water-based fracturing fluid for fracture stimulation and the preparation method thereof are further described by combining the following examples:

The composite water-base fracturing fluid for fracturing production-increasing measure is prepared through high-pressure pumping to squeeze it into reservoir stratum, and adding propping agent to fill in the cracks after many cracks are formed on the reservoir stratum.

The composite water-based fracturing fluid for fracture stimulation comprises the following components: the gel breaker comprises a thickening agent compounded by polyvinyl alcohol and modified guanidine gum, a compound organic boron crosslinking agent, a pH buffer solution, a gel breaker compounded by an acid-releasing gel breaker and an oxidizing gel breaker and water. Wherein the polyvinyl alcohol is formed by polymerizing 1, 3-glycol structure, the degree of hydrolysis of the polyvinyl alcohol is more than 75%, and the polyvinyl alcohol is more than PVA-1 of Shanghai King resin powder Co. The modified guar gum is hydroxypropyl guar gum model LD-HPG-1 from Lidak chemical plant of Yangzhou city.

The polyvinyl alcohol is used as a thickening agent to compound modified guar gum, the advantages of the polyhydric alcohol and the modified guar gum are fully utilized, and a novel low-damage and low-cost polyhydroxy alcohol compound water-based fracturing fluid system is developed. The polyvinyl alcohol provided by the invention is used as a thickening agent to compound modified guar gum, and has the harmless characteristic of the polyvinyl alcohol and the high-temperature and shear resistant performance of the modified guar gum. Through the compounding of the thickening agent, the filtration loss and the damage to a reservoir stratum are reduced, and meanwhile, the cost can be reduced. Therefore, the composite thickening agent has the characteristics of low damage and low filtration loss, is particularly suitable for ultra-low permeability oil and gas fields and dense gas reservoirs, and solves the problem of reservoir damage.

Wherein, the polyvinyl alcohol accounts for 1 to 2.5 percent of the total mass of the composite water-based fracturing fluid; the percentage of the modified guanidine gum in the total mass of the composite water-based fracturing fluid is 0.08-0.25%; the composite organic boron crosslinking agent accounts for 0.3-2% of the total mass of the composite water-based fracturing fluid; the pH buffer solution accounts for 0.2-0.3% of the total mass of the composite water-based fracturing fluid; the acid-releasing gel breaker accounts for 0.2-1% of the total mass of the composite water-based fracturing fluid; the percentage of the oxidizing gel breaker in the total mass of the composite water-based fracturing fluid is 0.01-0.06%; the balance being water. Preferably, the polyvinyl alcohol accounts for 1.5-2% of the total mass of the composite water-based fracturing fluid; the percentage of the modified guanidine gum in the total mass of the composite water-based fracturing fluid is 0.12-0.18%; the composite organic boron crosslinking agent accounts for 0.8-1.2% of the total mass of the composite water-based fracturing fluid; the pH buffer solution accounts for 0.22-0.28% of the total mass of the composite water-based fracturing fluid; the acid-releasing gel breaker accounts for 0.4-0.8% of the total mass of the composite water-based fracturing fluid; the oxidizing gel breaker accounts for 0.02-0.04% of the total mass of the composite water-based fracturing fluid; the balance being water.

Wherein the composite organic boron crosslinking agent comprises the following components: OB-II crosslinking agent, glycol, borax and water. OB-II crosslinkers are for example from the SiAn university of Petroleum works. The composite organic boron crosslinking agent comprises the following components in percentage by mass: 60-80% of OB-II crosslinking agent, 6-10% of glycol, 3-6% of borax and the balance of water. Preferably, the composite organic boron crosslinking agent comprises the following components in percentage by mass: 65-75% of OB-II crosslinking agent, 6.5-8% of glycol, 5-6% of borax and the balance of water.

The pH buffer is NaOH solution. Preferably, the concentration of the NaOH solution is 1%. The acid-releasing gel breaker is an acid-releasing organic ester, and can be triethyl phosphate, ethylene glycol dicarbamate, p-ethoxyanthracene sulfonate, and the like. The oxidative breaker is ammonium persulfate.

The preparation method of the composite water-based fracturing fluid comprises the following steps: uniformly stirring and mixing polyvinyl alcohol, modified guanidine gum, a composite organic boron crosslinking agent, a pH buffer solution, an acid-releasing gel breaker and an oxidizing gel breaker according to the mass percentage, adding water, and continuously stirring and mixing to obtain the composite water-based fracturing fluid.

The composite water-based fracturing fluid for fracturing yield-increasing measures is a low-residue and low-damage composite fracturing fluid system, can effectively reduce the filtration effect, improve the fluid efficiency and the fracture-forming capacity, and guarantee the success of construction. The composite water-based fracturing fluid can be applied to medium-low temperature ultra-low permeability and compact oil reservoir yield increasing measures, can effectively reduce residues, has low damage and filtration loss reduction performance, can effectively realize high temperature resistance and shear resistance, improves gel breaking performance and achieves the purpose of reservoir fracturing modification. The composite water-based fracturing fluid is a low-damage liquid system, has low-damage, high-temperature-resistant and shear-resistant performances, and is suitable for fracturing production increasing measures of low-permeability and ultra-low-permeability compact oil and gas reservoirs. The composite water-based fracturing fluid system has a good fluid loss reducing effect, can effectively reduce the fluid loss of the fracturing fluid in a stratum and a fracture, effectively increases the fluid efficiency, and improves the construction safety. The water-based fracturing fluid system disclosed by the invention has low residue and low damage performance, reduces damage by more than 65% compared with a conventional modified guar gum system, and can improve the fracturing yield of a low-permeability and ultra-low-permeability oil and gas reservoir by 1.5-5 times.

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.