Cementing provides a means of annular isolation so that hydrocarbon flow is permitted only at engineered locations in the well.  It prevents uncontrolled flow from reaching the wellhead; protects groundwater from hydrocarbon contamination; and restricts annular flow between formations. Operational parameters and well data must be analyzed to determine what products best complement the primary cement job in order to achieve reliable annular isolation. No single tool provides the perfect solution for every application. In many instances, a variety of tools may be utilized on a single string to effectively achieve cement integrity for the life of the well