Abstract: A sidepocket mandrel apparatus including a mandrel body formed of a resin-based material, such as, for example, fiberglass. The mandrel body defines a through-bore and an enlargement axially offset from the through-bore. A valve receiving pocket formed of a rigid material is secured within the offset enlargement of the mandrel body so as to be substantially parallel to but axially offset from said through-bore. Such pocket may, for example, be formed of stainless steel or of a composite plastic material.The sidepocket mandrel is formed by machining a valve receiving pocket from a rigid material. The valve receiving pocket is removably secured on a substantially cylindrical molding rod, together with at least one removable mold piece, the molding rod and removable mold pieces defining a desired inner shape of the sidepocket mandrel. Fiberglass is then wound around the valve receiving pocket, molding rod, and removable mold pieces to form a fiberglass mandrel body.

Abstract: In accordance with an illustrative embodiment of the present invention, a restriction sub apparatus for use during well cementing operations includes a tubular body having upper and lower internal recesses, a restriction ring having a shoulder engaged with the upper recess, and depending, inwardly inclined fingers at its lower end, and a back-up rubber ring mounted in the lower recess that yieldably resists expansion of the fingers as the drive plate of a displacement plug passes downward therethrough to provide a positive surface indication in the form of a pressure change that the plug is located at a particular depth.