CN-122012063-A - Nano elastic clean fracturing fluid system and preparation method and application thereof

CN122012063ACN 122012063 ACN122012063 ACN 122012063ACN-122012063-A

Abstract

The invention provides a nano elastic clean fracturing fluid system and a preparation method and application thereof, wherein the nano elastic clean fracturing fluid system comprises 0.05-0.60% of multi-branched polymer, 0.02-0.30% of nano emulsion and the balance of water, wherein the multi-branched polymer comprises polyacrylamide or partially hydrolyzed polyacrylamide, the tail end of the multi-branched polymer is provided with multi-branched assemblable monomers, and the electrical property of the multi-branched assemblable monomers is opposite to the electrical property of the nano emulsion. The nano elastic clean fracturing fluid system of the invention utilizes the electrostatic attraction between the multi-branch assemblable monomer and the nano emulsion to enhance the assembly effect and improve the performance of the nano elastic clean fracturing fluid system, such as excellent performance in aspects of shear recovery and drag reduction and seam making, and environmental protection characteristics of low residue injury, easy gel breaking, repeated use and the like.

Inventors

ZHOU FUJIAN
LIU XINLEI
ZHOU CUIHONG
LI FUYUAN
BAI HAO
DING ZHIYUAN
WU JUNLIN
ZHANG SAI
YAO ERDONG
LIU XIONGFEI
ZUO JIE
YANG KAI

Assignees

中国石油大学(北京)
北京科麦仕油田化学剂技术有限公司

Dates

Publication Date: 20260512
Application Date: 20251218

Claims (10)

1. A nanoelastic clean fracturing fluid system, characterized in that it comprises, based on 100% of the total weight of the nanoelastic clean fracturing fluid system, 0.05-0.60% of a multi-branched polymer, 0.02-0.30% of a nanoemulsion, and the balance water, the multi-branched polymer comprising polyacrylamide or partially hydrolyzed polyacrylamide, having at its ends multi-branched assemblable monomers, and the multi-branched assemblable monomers having charges of opposite electrical properties to those of the nanoemulsion.
2. The nanoelastic cleaning fracturing fluid system according to claim 1, characterized in that it comprises 20-50% of surfactant, 1-15% of alcohol, 0.1-10% of oil core and the balance water, based on 100% of the total weight of the nanoemulsion.
3. The nano-elastic cleaning fracturing fluid system according to claim 2, wherein said surfactant contains one or a combination of several of sulfonic acid group, sulfuric acid group and carboxyl group, or contains quaternary ammonium salt group; preferably, the surfactant comprises one or a combination of sodium benzenesulfonate, oleic acid and stearic acid with carbon chain length not less than C12 or comprises quaternary ammonium salt cationic surfactant.
4. The nano-elastic clean fracturing fluid system of claim 2 or 3, wherein the alcohol comprises one or a combination of several of methanol, ethanol, n-butanol, hexanol, oleyl alcohol, glycerol and polyethylene glycol; preferably, the oil core comprises one or a combination of several of synthetic hydrocarbon oil cores, natural terpenes, ester oils and silicone oil derivatives, more preferably the synthetic hydrocarbon oil cores comprise isoparaffins and/or hydrogenated polyolefins.
5. A nanoelastic cleaning fracturing fluid system according to claim 2 or 3, characterised in that in the nanoemulsion the particle size of the particles is stabilised in the range 3-25nm.
6. The nano-elastic cleaning fracturing fluid system of claim 1, wherein said multi-branched polymer has a molecular weight of 50-400 tens of thousands.
7. The nano-elastic cleaning fracturing fluid system according to claim 1 or 6, wherein said multi-branched polymer is an emulsion or a powder, and when said multi-branched polymer is an emulsion, the amount thereof is 0.10-0.60%, and when said multi-branched polymer is a powder, the amount thereof is 0.05-0.20%.
8. The nano-elastic clean fracturing fluid system according to claim 1 or 6, wherein the multi-branched polymer is obtained by copolymerizing acrylamide, acrylic acid and an assemblable monomer with positive or negative charges, or is obtained by copolymerizing acrylamide and an assemblable monomer with positive or negative charges; Preferably, the monomer capable of being assembled with positive charges comprises a quaternary ammonium salt monomer, and the monomer capable of being assembled with negative charges comprises one or a combination of a plurality of acrylic monomers, sulfonic acid monomers and monomers containing phosphate groups; also preferably, the degree of hydrolysis of the multi-branched polymer is from 0.0 to 20%.
9. The method of preparing a nanoelastic clean fracturing fluid system according to any one of claims 1 to 8, characterized by comprising: Adding the multi-branched polymer into water to obtain a polymer solution, and dissolving the nano emulsion into the polymer solution to obtain the nano elastic clean fracturing fluid system.
10. Use of the nanoelastic clean fracturing fluid system of any one of claims 1 to 8 in the hydraulic fracturing of unconventional oil and gas reservoirs.

Description

Nano elastic clean fracturing fluid system and preparation method and application thereof Technical Field The invention relates to a nano elastic clean fracturing fluid system and a preparation method and application thereof, belonging to the technical field of petrochemical industry. Background The hydraulic fracturing technology is a key means for improving the development efficiency of unconventional oil and gas reservoirs, and the slickwater fracturing fluid is used as a core working fluid of the fracturing fluid, so that the fracturing fluid has a decisive influence on the reservoir transformation effect. The polymer slick water is widely applied due to the excellent drag reduction performance, and the low-viscosity liquid can form a complex seam network under high-speed shearing in the application process, so that the volume of reservoir transformation is remarkably increased. However, conventional slick water has the inherent disadvantage that the low viscosity characteristic is beneficial to drag reduction and seam making, but sand blocking is easily caused by insufficient sand carrying capacity. While the sand carrying performance can be improved by increasing the molecular weight of the polymer and increasing the viscosity, the drag reduction effect can be obviously weakened, and the high mucus body can only form a single wide seam, so that an effective oil gas diversion channel is difficult to establish, and meanwhile, the problems of difficult gel breaking, high residue damage, low recycling rate and the like are faced. The current fracturing fluid technology has the limitation of evaluating system singleness, and excessively depends on viscosity indexes to neglect key factors such as sand carrying-drag reduction synergistic mechanism, seam network regulation and control capability and the like. The research shows that the performance of the fracturing fluid should comprehensively consider three core characteristics, namely elastic recovery capacity (the order of magnitude of elastic modulus is improved), the suspension stability of the propping agent is directly determined, the shear response characteristic is required to have intelligent rheological behavior of shear thinning-standing recovery (pumping viscosity eta <50 mPa.s, high elasticity recovered in a crack), and the reversibility of a network structure is realized, so that a physical assembly network can be more suitable for a dynamic shear environment compared with chemical crosslinking. Experimental data confirm that 60% of sand carrying efficiency depends on fluid elasticity rather than viscosity, which promotes the development of new generation fracturing fluid to the three-in-one direction of 'low viscosity drag reduction joint making-high elastic sand carrying-dynamic self-adaptation', so as to realize the cooperative optimization of complex joint network construction and efficient proppant delivery. Therefore, research and development and provision of a nano elastic clean fracturing fluid system for realizing intelligent order-of-magnitude improvement of elastic modulus thereof, synchronously meeting the requirements of drag reduction and joint making and efficient sand carrying, and having the advantages of low residue, easy breaking, repeated use and the like of environmental protection have become technical problems to be solved in the field. Disclosure of Invention In order to solve the defects, the invention aims to provide a nano elastic clean fracturing fluid system and a preparation method and application thereof. The nano elastic clean fracturing fluid provided by the invention utilizes the electrostatic attraction effect between the multi-branch assemblable monomer and the nano emulsion to enhance the assembly effect and improve the performance of the nano elastic clean fracturing fluid system, such as excellent performance in aspects of shear recovery and drag reduction and seam making, and environmental protection characteristics of low residue injury, easy gel breaking, repeated use and the like. To achieve the above objects, in one aspect, the present invention provides a nanoelastic clean fracturing fluid system comprising a multi-branched polymer, a nanoemulsion and water, which comprises 0.05-0.60% of the multi-branched polymer, 0.02-0.30% (preferably 0.05-0.10%) of the nanoemulsion and the balance of water, based on 100% of the total weight of the nanoelastic clean fracturing fluid system, the multi-branched polymer comprising polyacrylamide or partially hydrolyzed polyacrylamide, having multi-branched assemblable monomers at the ends thereof, and the multi-branched assemblable monomers having charges opposite to those of the nanoemulsion. In some preferred embodiments of the invention, the nanoemulsion is used in an amount that is half the amount of the multi-branched polymer. In the nano elastic clean fracturing fluid system of the invention, the terminal of the multi-branched polymer is provided with a multi-