无残渣压裂液的研制与应用

Research & development of a non-residue fracturing fluid.

聚合物压裂液残留物对压裂裂缝支撑带和地层渗透率造成难以恢复的伤害,严重影响了压裂改造效果。研制开发出了无残渣压裂液,该体系无聚合物,是一种粘弹性表面活性剂压裂液,由羧酸衍生物(NRF01a)组成。在盐水中,表面活性剂形成可变形的棒状或球状胶束,使溶液具有粘弹性,该液体遇水或碳氢化合物自动破胶,无残留物。通过评价该压裂液的流变性、破胶性能、伤害率和防膨性能得知,无残渣压裂液对裂缝支撑带的伤害率为6.9%,对储层基质的伤害率平均为19.4%;适用于110℃以下油气藏的压裂改造。现场试验表明,无残渣压裂液压裂后8d开始返排,返排率高达94.1%,返排液粘度为1.5mPa·s,表面张力为26.5mN/m,说明采用无残渣压裂液压裂,能更有效地启动油藏,并取得显著的增产效果。无残渣压裂液不污染环境,现场配制工艺简便。

After frac job, the polymer fracturing fluid residue may produce irreversible damage to the induced propping zone and the surrounding formation with permeability reduction, causing severe effect on the fracturing stimulation efficiency. To protect the productive formation, a non-residue fracturing fluid was developed. With no polymer in the liquid phase, it is a viscoelastic surfactant fluid composed of carboxylic acid derivative (NRF-01a). In salt water, the surfactants congregate into deformable rod or microsphere micelles, giving the solution viscoelastic property. The fluid breaks down automatically without any residue when encountering water or other hydrocarbon. Evaluation results of the rheology property, viscosity breaking and hydration property, damage rate and anti-dilatation property of the fracturing fluid showed that the damage rates to induced fracture propping zone and to the matrix were 6.9% and 19.4% respectively. In addition, this fracturing fluid was suitable for the reservoir lower than 110 ℃. In one trial, at the 8th day after the frac job, the fluid flew back with the recovery ratio as high as 94.1%. The viscosity of the fluid was 1.5 mPa·s and the surface tension was 26.5 mN/m. All these data verified that the non-residue fracturing fluid could be used to explore oil/gas reservoir effectively with substantially stimulation results. In addition, the fluid was friendly to the environment. It is easy to prepare and operate in field also.