松散地层密闭环保取心技术

大港港西、港东油田为典型的高孔高渗疏松砂岩油藏，在长期注水开发影响下地层水侵严重，采用传统松散地层密闭取心工艺很难保证取心收获率和密闭率。基于大港油田明化镇组、馆陶组地质特点和取心技术难点，针对传统密闭取心工艺作业效率低下、环境污染等问题，对内筒总成进行了优化设计，采用低冲蚀取心钻头，解决了水淹地层疏松砂岩取心收获率低及出心工艺复杂问题；通过改进密闭液加工工艺，得到低毒环保的氯化石蜡基密闭液，采用密闭液水浴加热法及密闭液回收装置，形成了安全、环保的密闭液处理工艺。现场2口井整体密闭取心成功作业表明，采取的技术措施科学合理，能有效提高密闭取心作业效率和取心质量，满足取心作业和钻井现场安全、环保的要求。

Environmentally-friendly sealed coring technology for unconsolidated formations

After long-term waterflooding development, the high-porosity, high-permeability unconsolidated sandstone oil reservoirs with the Gangxi Oilfield and Gangdong Oilfield of Dagang Oilfield as the typical ones suffer serious invasion of formation water, so the traditional sealed coring technologies for unconsolidated formations can hardly ensure the core recovery and sealing rate. To solve the low operation efficiency, environment pollution and other problems of traditional sealed coring technologies, the inner cylinder assembly was optimally designed based on the geological characteristics and coring technical difficulties of Minghuazhen Formation and Guantao Formation in the Dagang Oilfield. The low-erosion coring bit was adopted to deal with the low core recovery and complex coring process of watered-out unconsolidated sandstone formation. The low-toxicity environmental chlorinated paraffin based sealing fluid was prepared by improving the sealing fluid processing process. And the safe and environmental sealing fluid treatment process was formed by using the water-bath sealing fluid heating method and the sealing fluid retrieving device. The successful overall sealed coring in two wells indicates that the adoption of scientific and rational technologies and measures can effectively improve the operation efficiency and coring quality of sealed coring and satisfy the safety and environment requirements of coring operation and drilling site.