Influence of soft mudstone interlayer in clastic hailite deposits on drilling and the engineering countermeasures

Abstract:

This paper conducts an in-depth study on the drilling problems of soft mudstone strata in typical clastic halitite deposits in Shashi salt deposits in Jiangling Sag of Jianghan Basin. Through the analysis of the characteristics of the salt-bearing strata in and the actual drilling data of salt wells， the influence of soft mudstone on the safety， efficiency and quality of drilling engineering was systematically summarized. Based on this， a series of targeted drilling engineering technical countermeasures are proposed， such as the use of high-density undersaturated brine drilling fluid to balance the formation pressure， cone bit+screw+back reaming tool combination， and the testing drilling method of “retreat as advance”. These countermeasures have been applied in the actual drilling process， providing safety and quality assurance for subsequent construction， effectively reducing the probability of downhole complex conditions， and also providing important references for other drilling projects under similar geological conditions.