Abstract
The slim hole drilling technology satisfies the oil and gas industry demands todays. As it offers not only a significant cost reduction but also minimize the environmental impact generated from the drilling operation. The cost reduction is realized from using smaller rigs and tubulars and less cement, drilling fluid and drilling cutting disposal1. In general slim hole wells reduce costs by 40-60% for remote exploration wells and 25-40% of development wells compared to the conventional wells2.  The second main advantage of the slim hole drilling technology is the minimization of waste and improvement general environmental impact. If the size of the slim hole is half of a conventional one, the cuttings and mud volume will be 25% of a conventional volume2. Slim hole drilling technology has been impeded by the lack of documentation of well control methods for small annulus drilling3. One of the major barriers to the introduction of slim hole drilling technology to oil field operations was perceived to be the maintenance of safe standards of well control4. This paper will introduce a simple analysis of the pressures undergone by the well bore during killing operation so as to drive the optimum killing model for the slim hole wells.