适用于连续混配的耐120℃高温聚合物压裂液

Polymer Fracturing Fluid Suitable for Continuous Preparation with High Temperature Resistance of 120℃

为了解决压裂用聚合物粉剂产品在连续混配施工时排量波动及泵吸困难的问题,选取3种现场用稠化剂(胍胶、LP-1和LP-2低分子聚合物)作为研究对象,研究了聚合物溶液幂律关系、黏弹性及维森伯格爬杆效应等流变性,揭示其内在作用机制,构建了满足抗高温(120℃)的清洁压裂液体系,并进行现场矿场应用。实验结果表明:从幂律关系及溶液黏弹性可知,LP-1为线性分子结构且相对分子质量较高,其弹性及稠度系数较大,溶液维森伯格爬杆效应明显,导致现场泵吸困难,混液不均匀,致使排量波动。基于低爬杆效应的微支化缔合型聚合物LP-2,以“物理+化学”交联原理而构建满足工程应用的清洁压裂体系(配方为:0.3%LP-2+0.3%FA+0.25%GAF-5+0.3%FP-15+0.4%AP-5),该体系的基液黏度为35.5 mPa·s,120℃、170 s^(-1)剪切1 h的黏度为110.3 mPa·s,具有用量少、耐高温(120℃)、低伤害(残渣含量35.2 mg/L、对岩心伤害率为8.46%)、易返排(破胶液表面张力26.89 mN/m、与煤油间的界面张力为1.15 mN/m)等特点。该压裂液体系现场累计施工20余井次,按照设计完成加砂,最高砂浓度为400 kg/m^(3),施工排量平稳,施工成功率100%,为非常规致密油藏开发提供技术支撑。

In order to solve the problems of displacement fluctuation and pumping difficulty during continuous preparation process,three typical field thickeners such as guar gum,low molecular polymer LP-1 and LP-2 were selected as the research objects,and power-law relationship,viscoelasticity and Weissenberg effect of the polymer solution were measured to reveal their internal mechanism.The clean fracturing system with high temperature resistance of 120℃was constructed and applied in the field.The experimental results showed that,according to the power-law relationship and solution viscoelasticity,its elasticity and consistency coefficients of LP-1 with a linear molecular structure and relatively high molecular weight,were relatively large.The Weissenberg effect of LP-1 solution was obvious,which leaded to the difficulty of pumping on site,uneven mixture and fluctuation of displacement.Based on the micro-branched associating polymer LP-2 with low climbing rod effect and the principles of“hydrophobic association and chemical crosslinking”,a clean fracturing system for engineering application,composed of 0.3%LP-2+0.3%FA+0.25%GAF-5+0.3%FP-15+0.4%AP-5,was constructed.The viscosity of the base solution of the system was 35.5 mPa·s,and the viscosity of the system was 110.3 mPa·s after shearing for 1 h at the temperature of 120℃and at the shear rate of 170 s^(-1).It had the characteristics of low dosage,high temperature resistance(120℃),low damage(the residue content was 35.2 mg/L,the damage rate to rock core was 8.46%)and easy flowback(the surface tension of gel breaking fluid was 26.89 mN/m,the interfacial tension with kerosene was 1.15 mN/m).The fracturing fluid system had accumulated more than 20 well times of field operation,addition of proppant had been completed according to the design,the maximum sand concentration was 400 kg/m3.The construction displacement was stable,the construction success rate was 100%,which provided technical support for the development of unconventional tight reservoir.