长庆陇东地区油井压裂返排液配钻井液研究与应用

针对长庆陇东地区压裂返排液总量大、资源化利用率低的技术难题，以“减量化、资源化”为核心，通过对陇东油井区域4种典型压裂返排液样品的基本性能、离子成分、生化指标、发泡性能等分析研究，确定出返排液配制钻井液的主要影响因素。针对研究得出的影响因素开展了返排液预处理除砂设备、杀菌剂、抑泡剂及离子去除剂的优选评价等，同时结合长庆油气田现场生产实际确定出返排液预处理工艺技术流程，并在水资源短缺的长庆陇东致密油大井组水平井华H20-*平台完成2口井压裂返排液预处理及配制钻井液技术研究先导性试验。现场应用结果表明，预处理后返排液配制的钻井液同生产用水配制的钻井液性能基本接近，密度为1.25~1.30 g/cm3，表观黏度损失率可控制在15.0%以内，试验井段井壁稳定、钻井液滤失量、发泡性能可控，能够很好地满足现场钻井液使用要求。该研究及应用为压裂返排液配钻井液技术的推广及提高水资源综合利率奠定基础。 

Study on and Application of Drilling Fluids Formulated with Fracturing Flowback Fluids in Longdong,Changqing Oilfield

Fracturing operation in Longdong, Changqing Oilfield produced very large amount of fracturing flowback fluids which were seldom reused because of technical obstacles. To minimize the amount of the fracturing flowback fluids discarded as waste fluid and to turn them into useful resources, four typical fracturing flowback fluid samples taken from oil wells in Longdong were studied for their basic properties, ionic composition, biochemical specification and foaming performance to determine the major factors affecting the formulation of a drilling fluid with the fracturing flowback fluids. Based on the affecting factors determined, desanders, biocides, foaming inhibitors and ion removers for the preprocessing of the fracturing flowback fluids were selected and evaluated. A preprocessing technical procedure for preprocessing the fracturing flowback fluids was developed, taking into account the field practice prevailing in Changqing Oilfield. As a pilot test, fracturing flowback fluids produced from two wells on the horizontal well platform Hua-H20-* in Longdong area (a block with tight oil reservoir) where water shortage has long been a problem were preprocessed and then used to formulate a drilling fluid. The results of the pilot test showed that the properties of the drilling fluid formulated were very close to the properties of the drilling fluids formulated with makeup water; the density of the drilling fluids formulated was 1.25-1.30 g/cm3, and the rate of loss of apparent viscosity was less than 15.0%. Borehole wall was stable in the sections drilled with the drilling fluid formulated with the fracturing flowback fluids, and the drilling fluid had filtration rate and foaming performance that were well under control, highly satisfying the needs of the drilling operation. This study has laid the foundation for formulating drilling fluids with fracturing flowback fluids and maximizing the overall utilization of water resource.