The Mining well can mine in a 1x1 hole below it with out a line of sight.
You should also know that when powering more than 10 at one time you will need massive power. You would need at least 5 Energy Links hooked up to 5 High Voltage Solar Arrays each to make them go fast, and using one quarry would be more efficient and cheaper.
Caution: The piping left behind by the Mining Well will not fill up the entire block beneath it. Use caution when breaking your Mining Well as the block or even you may fall down the hole you have created.