Casing Design Reevaluation in South Iran Oil Field

size and type of the casing is chosen based on the geology and formation properties of the field. Cost of the casing design is more than 30% of overall drilling cost which make it an expensive operation for each well. Saving in this operation causes huge reduction in total expenditures of drilling. It seems that it is accessible to reach an optimum method by complete analyzing and reevaluating of the relevant factors in customary design programs which are done traditionally in the Iranian Oil fields. In this paper, by using minimum-cost casing design two methods are proposed for Iranian oil field. In the first proposed method, 30 in conductor casing is used and completed with 7 in liner which make it suitable for high producing field. This method save 17.31% cost of casing design compare to traditional method. The application of the second method is not restricted to special condition and it is compatible to the all cases. This method saves 17.4% cost and also providing sufficient stability and safety in casing program by using two liner and prevent unnecessary cost and time-consuming operations. Finally these two methods are applied to south and southwest Iranian oil field.