Overcoming Shallow-Gas Drilling Difficulties

摘要

Shallow gas-bearing formations in the Gulf of Thailand present numerous drilling and cementing challenges,hi the first three wells drilled on platform WP11 in Bongkot field,initial cementing of surface casing did not achieve effective zonal isolation of the shallow-gas zone.Use of conventional lightweight gaslight cement slurries,two-stage cementing operations with conventional gas-migration-control slurries,and injection of sodium silicate to damage the shallow-gas sand failed to control the gas migration through permeable upper sand layers.The full-length paper presents case histories describing the solutions-oriented approach to this problem that resulted in changes to the drilling program and cementing operations.