Wire-line Core Drilling Technology in Shale Gas Wells with High Pressure Gushing Water and High H2S Content

Abstract:

The designed depth is 1600 meters for the shale gas survey well Yingdi-1. During the construction process, several high stress water gushing fractured zones were encountered, the largest watering quantity was 135m3/h and wellhead pressure was up to 2.5MPa; there was hydrogen sulfide dissolved in formation water, the highest content of hydrogen sulfide gas escaped from the gushing water was up to 100ppm; the water temperature is high up to 50℃ in gushing spot at 1300 meters depth, these difficulties brought safety risk to the construction. In view of the above, this paper introduces water plugging technology by cement slurry grouting, balanced drilling technology with high density drilling fluids and multistage casing technology for well cementing used in drilling process and summarizes the characteristics of each technology, which can be reference for the shale gas investigation well drilling construction in Southwestern Sichuan.

Key words:high pressure water gushing layer; high H2S content; water shutoff technology by cement slurry; high density drilling fluid; multistage casing technology for well cementing