Abstract: The analysis on accurate location by lead pattern and multi-arm calliper shows that damage points of casing in the member Ⅱof Nenjiang Formation in Daqing Oilfield are mainly concentrated on N₂ marker bed.The damage pattern is shear casing damage.The most serious casing damage sheared at the bedding plane which corresponds to the highest peak of six peaks of 2.5 meters apparent resistivity in N₂ marker bed.The N₂ marker bed is a set of fossil assembly.The six peaks of 2.5 meters apparent resistivity is closely related to fossil quantity.The more fossil in N₂ marker bed,the higher apparent resistivity peaks.Since the N₂ marker bed is a kind of hard rock mainly consisting of CaCO₃ and SiO₂ and also the fossils densely distributed along bedding which would have the weakest plane at the highest peak of apparent resistivity,both hard rock and weak plane are the key geological factors resulting in batch casing damage in N₂ marker bed.The N₂ marker bed deposited in the period of the largest lake transgression in the Cretaeous,so its depositional environment and characteristics have regional consistent,which is the geological base for resulting in casing damage in the same layer but in different areas in Daqing Oilfield.

Key words: Daqing Oilfield, member Ⅱ of Nenjiang Formation, N₂ marker bed, casing damage, apparent resistivity, geological factor

摘要： 对套损铅印和多臂井径精确定位分析发现,嫩二套损点集中在其底部标志层段,力学性质属于剪切套损.其中最严重的套损剪切面位于标志层所对应的2.5m视电阻率曲线的6个特征峰值中最高的第3个峰值上.嫩二标志层是一套化石层组合,2.5m视电阻率曲线的6个特征尖峰与地层化石含量密切相关.化石含量越多,电阻率尖峰值越高.嫩二标志层泥岩因富含钙质而坚硬,又因化石沿层理面密集分布而具有薄弱面,且在电阻率最高峰值处表现最薄弱,这是导致成片剪切套损的重要地质因素.在松辽盆地,嫩二标志层沉积于白垩纪最大湖侵时期,沉积环境与沉积特征具有区域上的一致性,这是导致大庆油田在不同区块同一层位发生成片套损的地质基础.

关键词: 大庆油田, 嫩二段, 嫩二标志层, 套管损坏, 视电阻率, 地质因素