古近系地层取心钻进速度影响因素初步分析

河北平原古近系地层主要发育有东营组、沙河街组和孔店组，其岩性以泥灰岩、泥岩、钙质泥岩、石膏泥岩和砂岩为主。影响取心钻探钻进速度的物理力学因素较多，本文主要以岩石密度、抗压强度和弹塑性为主进行了研究分析。研究得出岩石密度和抗压强度均随着地层深度的增加而增加，古近系东营组和沙河街组一段至三段岩石密度明显低于沙河街组四段和孔店组，钻进取心速度差异明显；古近系地层中的泥岩段由于粘土矿物成分占比增加造成岩石弹塑性增强，对钻进速度的影响比较明显；文中提出了古近系地层取心钻探过程中地层的可钻性级别及合理的钻头类型匹配。

Preliminary analysis of the influencing factors of core drilling rates in the Paleogene strata

The Paleogene strata in Hebei Plain mainly consist of Dongying Group, Shahejie Group and Kongdian Group, which are lithologically marl, mudstone, calcareous mudstone, gypsum mudstone and sandstone. There are many physical and mechanical factors that affect the core drilling rate. The study shows that the rock density and compressive strength increase with the formation depth. The rock density of the first to the third member of Dongying Group and Shahejie Group is significantly lower than that of the fourth member of Shahejie Group and Kongdian Group. The higher content of clay minerals in the mudstone section of the Paleogene strata results in greater elasticity and plasticity of the rock, which has a significant influence on the drilling rate. In this paper, the drillability of the Paleogene strata and the reasonable matching bit types are presented for core drilling.