Abstract: Novel retainers for a body threaded into a reciprocating pump used for pumping fluid into a well are provided for. They comprise one or more elastic members adapted to flex and allow the retainer to be interlocked with the pump and a member adapted to engage the threaded body and to limit loosening thereof. Preferably, the engagement member is biased into engagement with the threaded body, for example, by elastic, magnetic, or gravitational potential energy. The novel retainers include stops which limit loosening or tightening of the threaded body and pawls that limit loosening of the threaded body.

Abstract: 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.

Abstract: 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.