A Study Of Hydrophobically Associating Water-Soluble Polymer/Surface Active Agent Compound System Applied In Low Damage Fracturing Fluid

In recent years, with the exploitation of oil gas well coming into the anafase stage, hydraulic fracturing has already shown its importance more and more as one of technical measures of oil-gas increasing production and water well augmented injection. In the course of fracturing construction, stand or fall of fracturing fluid has become the key factor of construction measure . At present, the most usually used fracturing fluid is water-based polymer fracturing fluid. Although its performance is fine, it brings too large damage to stratum. And newly developed clean-fracturing fluid has small damage and even ho damage to stratum, but the cost is too high to apply it widely. These conditions compelled us to exploit the new fracturing fluid which possesses performance of high quality, low cost and low damage.Through analysing the requirement of oil field to application fracturing fluid and relating to the merits and faults of the existed fracturing fluid, the imagine that hydrophobically associating water-soluble polymer/SAa compound system could be used as low damage fracturing fluid was put forward. And the performance which could satisfy the construction requirement of low damage fracturing fluid was drawn by analysing the performance traits of compound system.So, according to the requirement of low damage fracturing fluid to the structure of polymer molecule, series of hydrophobically associating water-soluble polymers which have the performance of instant, low-molecular weight, high hydrophobical monomer content and low content of water undissolved substance was designed and synthesized. And the feasibility of acting as low damage fracturing fluid of it and SAa compound system was systematically researched. Experiments showed that: The compound system possesses fine tackify character, shear-thinning property, viscosity recovery characteristic at low shear, notable viscoelastic effect, certain temperature resisted property and salt tackify property; Viscosity of compound system can be broken quickly and completely by using routine viscosity break method of polymer fracturing fluid; Temperature-resist of the compound system can reach to 115℃ according to the requirement of normal carrying and transporting proppant of polymer fracturing fluid to viscosity; The damage rate of filtration fluid of compound system to lithology basal mass permeability is under 11%, that is to say, using the compound system as fracturing fluid can notably reduce the damage of fracturing fluid. Thereinto, breaking viscosity of mechanism and damage mechanism of compound system had been simply analysed ,too.Through measuring other performance of compound system by the merit standard of water-based fracturing fluid and combining the said performances, the compound system was confirmed finally that it can satisfy the performance requirement of low damage fracturing fluid construction. So the hydrophobically associating water-soluble polymer/SAa compound system which can be applied to low damage fracturing fluid has been successfully exploited.