Case study and analysis of cement plugging technology for core drilling in lost circulation formation
In this study,the 1000m core drilling of hole ZK407 in the southern and peripheral gold polymetallic resources investigation and evaluation project in Shandong Zhaoping Belt is taken as an example to analyze the technical difficulties of deep gold deposit drilling in Jiaodong area under the background of fault development.The borehole is located in Qingshan village,Nanshu Town,southern end of Zhaoping fault zone.The gold deposit is mainly altered rock type and quartz vein type located in the fracture zone.In the process of drilling,some accidents occurred,such as groundwater pressure imbalance,hole collapse and block clamping,serious leakage and drilling burning.In order to solve these technical problems,some measures have been taken,such as casing isolation,adjusting mud performance,composite material plugging,top leak drilling and cement plugging.These measures have effectively solved the technical problems,achieved the expected goals,and provided qualified geological drilling and physical core data for the research of deep mineral mineralization theory and resource exploration in this area.The results of this study have important reference value for drilling engineering under similar geological conditions.
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