Stochastic Approach to Kick Tolerance Determination in Risk Based Designs

Abstract Drilling experience in the Niger Delta has shown that inappropriate selection of kick tolerance could constitute a serious setback to the implementation of cost effective and innovative solutions in well designs. While a conservative selection of kick tolerance could make a well design uneconomical, attracting severe cost penalties by fostering use of expensive / extreme pressure-ratings BOPs and extra casing strings sometimes, undue tightening of the tolerance on the other hand could make a well undrillable from safety point of view. This consideration poses serious dilemma to the well engineer who must balance the demands of conflicting alternatives in his management of design risks. To resolve this, the approach of stochastic analysis procedures to the prediction of appropriate design kick tolerance in any given geological setting and operational environment is being presented in this paper. Since this approach depends largely on the use of historical kick records, certain concerns regarding the reliability and acceptability of the use of historical data for the purpose of kick tolerance modeling and selection were equally addressed. Finally, a well example shows how this method has been used to integrate kick tolerance considerations in the management of design risks associated with the deployment of new technology application, expandable sand screen, in a high rate horizontal oil producer.