东北油气田压裂液返排液重复利用技术

Study on Reuse of Fracturing Fluid in Oil and Gas Fields in Northeast China

针对压裂液返排液量大,净化处理成本高,对环境污染严重的问题,对东北油气田压裂液返排液重复利用进行了研究。设计并研发了移动式污水处理装置,通过该装置制取了清洁压裂液和瓜胶压裂液2种返排液的处理液。用Master sizer 2000激光粒度仪对处理液进行分析,结果表明,处理液中的固相颗粒去除率达到99%以上。对处理液进行了水质分析,结果表明2种处理液中仍含有大量的Ca2+、Mg2+等离子,北201井处理液中还存在难去除的硼酸根离子,这使得配制的HPG基液提前交联,形成冻胶;北201井中高浓度的Ca2+、Mg2+使得CMG稠化剂不能溶胀起黏。通过对不同添加剂的优选和用量优化,确定了利用处理液配制BCG-1非交联缔合型压裂液的最佳配方:0.5%稠化剂BCG-l+0.2%阻垢剂B-43+0.3%金属离子螯合剂BCG-5+0.1%高温稳定剂B-13+0.4%黏度增效剂B-55。性能评价表明:2种处理液配制的压裂液在120℃、170 s-1下剪切120 min液体黏度均能达到30 m Pa·s以上,耐温耐剪切性好;落球沉降速度小于0.324 mm·s-1,携砂性好;破胶彻底,破胶液黏度小于5 m Pa·s,残渣含量低于30 mg/L。

Large amount of fracturing fluids recovered during fracturing jobs in oilfields in northeast China imposed serious contamination to the environment and the cost spent in the purification of the fluids was high. A portable waste water disposal equipment was developed in an effort to reuse these fluids. A used clear fracturing fluid and a used guar gum fracturing fluid were disposed of with this equipment, and the produced fluids were analyzed with a laser particle size analyzer(Model: Master sizer 2000), showing that more than 99% of the particles in these fluids had been removed, while large amount of calcium and magnesium ions were found in the fluids after water analyses. Fracturing fluids used in the Well Bei201 had borate ions that were difficult to remove and reacted with HPG base fluid to form a viscous gel. The calcium and magnesium ions in the fracturing fluids caused the CMG to lose its function as a thickening agent. Based on these analyses, an optimum fracturing fluid formulation was developed using the reused disposed fracturing fluid:0.5%BCG-1+0.2%B-43+0.3%BCG-5+0.1%B-13+0.4%B-55, which was a non-crosslinking fracturing fluid. The new formulation had viscosity greater than 30 m Pa·s after shearing 120 min at 120 ℃ and 170 s-1, settling speed of falling ball less than 0.324 mm/s, viscosity of the gel-broken fluids less than 5 m Pa.s, and residue content of the gel-broken fluids less than 30 mg/L.