Use of expanding cement improves bonding and aids in eliminating annular gas migration in hobbs grayburg-san andres wells

Annular gas migration and poor cement bonding throughout much of the wellbore have been continual problems in the primary cementing of Hobbs Grayburg-San Andres Wells. This paper discusses the formulation of an expanding cement system and the implementation of good primary cementing techniques to improve cement bonding and to eliminate annular gas flow after cementing. The work is based on a review of previously unsuccessful attempts to control annular gas flow by conventional gas control methods typically used by the industry. Case histories, cement bond logs, previous primary cement slurries, and procedures used in the field are presented with possible explanations of why they failed to control the problem. The formulation of the primary cement system is outlined in detail including refinements made to the system during the 1984-85 drilling program.