用油田回注污水配制水基压裂液的研究与应用

Experimental Study and Applications of Preparing Fracture Fluid Using Re-Injected Oilfield Wastewater

为了解决陕北油田压裂施工用水短缺的问题,研究应用油田回注污水配制水基压裂液。在分析陕北油田回注污水水质的基础上,进行了回注污水pH值对压裂液性能的影响试验、回注污水与压裂液添加剂的配伍性试验及用回注污水所配制压裂液性能的评价试验。试验结果表明:回注污水与压裂液添加剂配伍性较好;用回注污水配制压裂液时,回注污水的pH值应为7-8,稠化剂加量不小于0．5％,稠化剂与水混合时间不小于20 min;用回注污水配压裂液的使用最佳时间在配制好后8 h以内,回注污水压裂液与清水压裂液相比除破胶快外,其余性能指标基本相当。陕北油田应用油田回注污水配制的压裂液进行了20余井次的压裂施工,施工效果表明,该压裂液能满足陕北油田低温地层对压裂液性能的要求。

In order to solve the shortage of fracturing water in the Shanbei Oilfield, a study is initiated, it is intended to prepare water-based fracturing fluid using re-injected wastewater. On the basis of analysis on wastewater quality, wastewater has been experimented with respect to effects of pH on fracturing fluid properties, compatibility with additives, and property evaluation, etc. Experimental data proves its good compatibility. When preparing fracture fluid using re-injected wastewater, its pH should be 7-8, the additive more than 0. 5%, mixed time over 20min, the best operation duration is within 8 hours since getting it prepared. Such fracturing fluid, in comparison with one prepared by fresh water, performs equivalent functions except the faster gelout velocity. This technology has been successfully applied in more than 20 cases in the Shanbei Oilfields. Operational effectiveness show that this fracturing fluid can meet demands for fracturing low temperature formations.