The Making of Oil
Production 

How do you protect the reservoir? 

Once you drill into the reservoir, you face a new challenge: Keeping an open pathway for oil to move into the well.

Inside the borehole, drilling fluid -- also known as "mud" -- lines the well with a residue, called "mudcake." If the mud is not customized for the job, mudcake -- here in brown -- can invade the rock and plug the pores between rock grains. Oil, here in green, can't penetrate this barrier. But if the drilling fluid is changed to fit well conditions, it will not block the path of the oil. Oil can then find its way through the rock pores, through the mudcake, and into the well.

How do you reach the oil reservoir quickly and safely?
How do you tap the most oil per well?
How do you extend the life of the oil reservoir?