No, it's a matter of the complicated and only partly known geology underground. See other answer. Another way of looking at it is: You've drilled holes to make

No, it's a matter of the complicated and only partly known geology underground. See other answer. Another way of looking at it is: You've drilled holes to make the oil flow. There are kilometers of rock on top of the oil layer, pushing down, pushing the oil towards the holes you've drilled. You can close the end of the hole, but you can't make that weight go away. The system is going to find a new equilibrium. The new equilibrium is not one you've tried to optimise for maximum total oil production.