The primary challenge in drilling shallow depth viscous oil formation in Kuwait is to achieve gauged holes while drilling in unconsolidated friable sand-shale alteration. Gauged holes are the key for the production techniques used in this field, where cement channeling and perforation effectiveness are of main concern. To achieve this, a specific drilling fluid design was necessary. Laboratory tests and extensive research were initiated to customize the drilling fluid parameters and wellbore hydraulics necessary to achieve the primary drilling objectives.
The drilling fluid design goal was to provide enhanced clay inhibition for the clay strikes, gave good lubricity and low friction coefficient to ensure the smooth drilling and tripping operations in a gauged hole profile. Additionally, the environmental advantage of avoiding the generation of drilling waste with high chloride content was achieved, therefore contributing to KOC’s HS&E goals.
Fluids viscosity and hydraulics were designed in high profile to remain completely in laminar flow while drilling to minimize washout occurrence and maximize hole cleaning at low circulation rates (140 – 150 GPM) without the use of regular sweeps. The customized drilling parameters and practices, in addition to the knowledge gained from the laboratory testing phase, were transferred to the field. This resulted in proved success with more than hundred and twenty five perfect gauge holes