Abstract
The development of giant oil field "Mumbai High" has been a learning platform for the role that drilling fluids play in the successful rejuvenation program of any oil field. This paper attempts to manifest the learning curve right from the low angle wells drilled using simple conventional systems limiting the role of fluid services to the basic functions of enabling the normal drilling process. Over the years when farther parts of reservoir were explored at higher angles, the crucial role of the inhibition, bore hole stress management were exposed. The ultimate challenge was posed by the horizontal program where in the grey areas of cutting bed formation, hole cleaning, imperative drilling and drilling fluid practices dictated the completion of any well. The final Phase of the ERD program showed the critical aspect of minimization of pore pressure transmission and gauge of hole to the successful drilling of any well. The chronology has dictated the imperative selection of the right drilling fluid for each phase starting from the change over to the non-dispersed KCL-PHPA systems the Cloud point Glycol system via the most inhibitive Silicate system and culminating with the selection of Synthetic Oil Base Mud for the long horizontal wells. The redevelopment program indicated that there are no degrees of freedom as far as the inhibition, hole cleaning, bore hole stress management and drilling practices are concerned, and that is up to the drilling fluid chemist to play a proactive role to fill in the grey areas between the driller, G&G and the drilling fluids.
