东北油气田可重复利用地层水基压裂液

针对东北油气田压裂液配液水缺乏及地层水重复利用难的问题，开展了东北油气田地层水特征分析及可重复利用压裂液研究。地层水特征分析以及地层水压裂液优选实验结果表明:苏家屯等几个区块地层水呈弱碱性，生物活性强、Ca2+、Mg2+含量高，使得常规稠化剂溶胀速度慢甚至沉淀、配制的基液稳定性差并且交联无法控制、交联液耐温能力差。最终确定了能采用地层水配制的BCS分子自缔合压裂液及130 ℃配方:0.55%稠化剂BC-S+0.45%稠化增效剂BL-S+0.3%金属离子稳定剂BCG-5+0.2%高温稳定剂B-13+0.3%高效阻垢剂BC-3。性能评价结果表明:BCS压裂液在130 ℃、170 s?1下剪切120 min黏度可达35 mPa·s以上，耐温抗剪切性能良好，携砂性能优于HPG压裂液，并且破胶彻底，破胶液残渣含量仅为1.5 mg/L，表面张力为24.32 mN/m。采用60%的自来水稀释压裂返排液后，配制的BCS压裂液能达到原130 ℃配方的标准，从而实现地层水的多次重复利用。

Reusable fracturing fluid based on formation water in Northeast Oil and Gas Field

In Northeast Oil and Gas Field, the dispending fluid of fracturing fluid is deficient and formation water cannot be recycled easily.To solve these problems, the characteristics of formation water in Northeast Oil and Gas Field were analyzed and the reusable fracturing fluid was investigated.It is indicated from formation water characteristic analysis and formation water based fracturing fluid optimization experiments that the formation water in several blocks (e.g.Sujiatun) is characterized by weak alkaline, strong bioactivity and high contents of Ca2+ and Mg2+.As a result, the conventional thickener swells slowly and even precipitates, the stability of prepared based fluid is poor, crosslinking is uncontrollable and the temperature resistance of crosslinked fluid is poor.Ultimately, the BCS molecular self-association fracturing fluid based on formation water was adopted and its 130 ℃ formula is 0.55% thickener BC-S+0.45% thickening synergist BL-S+0.3% metallic ion stabilizer BCG-5+0.2% high temperature stabilizer B-13+0.3% efficient antiprecipitant BC-3.Its performance was evaluated.It is indicated that after BCS fracturing fluid is sheared for 120 min at 170 s-1 under 130 ℃, its viscosity is high than 35 mPa·s.Its temperature resistance and shear resistance are good.Its proppant carrying capacity is better than that of HPGfracturing fluid.Its gel breaking is complete with the content of gel breaker residue only 1.5 mg/L.Its surface tension is 24.32mN/m.After the flowback fracturing fluid is diluted with 60% tap water, the BCS fracturing fluid can satisfy the criterion of original 130 ℃formula, and thus the formation water can be recycled many times.