Abstract
This paper considers the risks of losing a well due to too low a mud weight in comparison to the fluid pressure gradient. In addition, inclusion of potential financial gains and losses are incorporated. When parameters can be uncertain, both from the drilling aspects of the problem as well as the financial aspects, then it is shown that the probability of losing the well, as well as the probability of reaching a financial break-even status, both have uncertainties. The relative contributions of uncertainties in drilling parameters on their own, of uncertainties in financial parameters on their own, and of the combined drilling and financial parameter uncertainties to both the chances of losing the well and the chances of making a profit are examined, as are the relative contributions of all such uncertain parameters to the variance in the uncertainty. In this way one can identify which of the uncertain parameters is causing the greatest contribution to the uncertainty of losing the well and the risk of making a loss rather than a profit.