新近系地层大直径取心质量影响因素分析及对策研究

Analysis of factors influencing the quality of large diameter coring inNeogene strata and research on countermeasures

在郑州市主城区与东部新城区地热资源勘查评价项目中,勘查目的层为新近系明化镇组和馆陶组,在勘查初期存在取心质量不稳定的问题。通过对影响取心质量的地质因素和工程因素的分析发现,初期采用的川7-4型单动双管取心工具配装的卡箍式岩心爪,难以适应胶结程度差异大、复杂多变的新近系地层。针对影响取心质量的因素,采用了钙化泥浆,优化了钻进参数,改进了钻头结构,设计加工了卡板式岩心爪与卡箍式岩心爪组合的双作用岩心爪。在后续的勘查施工中,有效提高了岩心采取率,解决了取心质量不稳定的问题。

In the geothermal resources exploration and evaluation project in the main urban area and the eastern new urban area of Zhengzhou City,the Neogene Minghuazhen Formation and Guantao Formation is the target layer,where the problem of unstable coring quality exists in the early stage of exploration.Through the analysis of geological and engineering factors which affect the coring quality,it was found that the early used Chuan7-4 type single move double tube coring tool with slip⁃collar type core gripper is difficult to adapt to the Neogene strata which is of large difference of cementation degree,complex and changeable.In view of the factors that affect the coring quality,calcified mud was used,drilling parameters were optimized,structure of the drilling bit was improved,double action core gripper with card plate and slip⁃collar was designed and processd.As a result,the coring rate was effectively improved and the problem of instable coring quality was solved in the subsequent exploration construction.