Improved Model for Predicting Annulus Pressure Drop during Underbalanced Drilling

When a well is drilled underbalanced, hydrocarbon production begins as soon as productive zone is penetrate. It is possible to produce portion of the reservoir fluid while drillingor cleaning the hole. With suitable processing equipments, some underbalanced wells may pay for their cost entirely from production before drilling operations were completed. 

The technique requires the simultaneous flow of fine drilling cuttings and formation fluid (gas, oil and water). If the pressure profile in an underbalanced well can be predicted within reasonable accuracy, it would be possible to get good estimates of the power required to lift the accumulated cutting and formation liquid while drilling or cleaning the hole. Read more>>>>>>>>>>>>>>