Establishing communication downhole between wellbores

A method of establishing fluid communication between wellbores can include forming a flow path from one wellbore to another wellbore, a flow area of the flow path increasing in a direction from the first wellbore toward the second wellbore. An explosive assembly for use in a well can include an explosive device having multiple explosive charges, the explosive charges producing longitudinal shock waves that collide with each other and result in a laterally directed shock wave, and a shield that focuses the laterally directed shock wave into a predetermined angular range of less than 360 degrees. A method of establishing fluid communication between wellbores can include forming a flow path from one wellbore to another wellbore, the flow path intersecting an uncased portion of the second wellbore.