Under-Balance Drilling (UBD) has been used in several carbonate fields of the Cluster, North Oman at Petroleum Development Oman (PDO). The reasons have been to improve productivity and injectivity, real-time reservoir characterization and to reduce/eliminate acid clean out. By using UBD in several fields, a better picture of well candidate selection and benefits has been derived.
In this paper we will present the results of successful utilization of UBD that may be applied to other fields. The results include an improvement in productivity, real-time decision making and a better understanding of reservoir flow characteristics. In summary the success of UBD depends on the selection of the fields which we elaborate on using several examples. These examples will demonstrate in details the history, application and benefits of UBD. The presentation will also illustrate future work planned using UBD.