A downhole fluid injection system comprising: a first fluid line including a first end, a second end, and an intermediate portion, the first end being connected to a fluid source, the first fluid line being extendable along a first portion of a wellbore; and a second fluid line including a first end section, a second end section, and an intermediate section, the second fluid line being extendable along a second portion of the wellbore that extends at an angle relative to the first portion and includes a plurality of fluid injectors arranged along the intermediate section.