Wellbore instability is the largest source of trouble in drilling, affects waste of huge time and overall costs during drilling. Studies indicate that unforeseen event relating to wellbore instability account for more than 10-20% of well costs, with estimates over US $1 billion in annual cost to the industry. And, 90% of the wellbore instability mainly occurs in shale and mudstone, which represent 75% of formation in oil and gas wells.
Therefore, drilling fluid company has been introducing various materials as a composition of drilling fluid for shale inhibition for over 100 years. New technologies has been continually developed or applied, after refining existing technology.
Author look back on a long history of drilling fluid technology related to shale inhibition as a measure of forecasting the future direction of same technology.
