Embodiments of the present invention include methods and apparatus for treating a formation with fluid using a downhole progressive cavity pump (“PCP”). In one aspect, the direction of the PCP is reversible to pump treatment fluid into the formation. In another aspect, two or more PCP's are disposed downhole and reversible to allow a chemical reaction downhole prior to the treatment fluid entering the formation. In yet another aspect, embodiments of the present invention provide a method of flowing treatment fluid downhole using one or more downhole PCP's. Treatment of the formation with the fluid and production of hydrocarbon fluid from the formation may both be conducted using the same downhole PCP operating in opposite rotational directions. In an alternate embodiment, one or more downhole PCP's may be utilized in tandem with one or more surface pumps.