Integrating risk management concepts into the drilling non-productive time

Abstract

Introducing the non-productive time (NPT) concepts in the 1960s was a necessity dictated by the ever-increasing cost and complexity of the oil and gas well drilling. The NPT definition stayed unsettled until two decades later, the definition converged toward its accepted current definition of “the time when planned or out-of-plans drilling-related activities do not add value to the operation objectives.” NPT as it is defined in drilling nowadays is a form of time waste or loss which adversely impacts the overall efficiency of the drilling operation. Since the 1980s, risk management (RM) has become a sound technique to evaluate operational losses or wastes of many resources, including time. This paper presents an attempt to couple RM techniques with NPT philosophy together with other concepts such as Systems Thinking, Synergy, Continuous Improvement, and Total Quality. These concepts and derived techniques suit well controlling the intolerable waste that shows up in the form of delay in operations and materializes into most of the undesirable costs of drilling. These concepts, adopted herein, were applied on data from 60 rigs which were used to drill 250 wells for a period of 1 year of operation. In all 19 types of NPT were considered. A Java software model was developed and used to express NPT as an undesired event with probability of happening, in order to follow with RM terminology. The probability levels (related to the NPT values) for each rig were then defined and further classified into the four familiar ranks and their colors as used in RM: Acceptable (green), Tolerable (yellow), Inadmissible (orange), and Unacceptable (red). A matrix was established for all NPT categories and for the 60 rigs and was then named Rig-NPT Risk Matrix. A maximum probability ceiling was established as a reference for unacceptable risks of all NPT categories and for all the 60 rigs. Finally, sets of risk control recommendations were proposed to minimize the NPT in order to improve rigs performance. The concept of NPT and the science of RM when integrated gave a new approach to minimize the drilling losses. Using NPT analysis coupled with risk management was used to indicate where to optimize exerted efforts in order to synergize improvement of overall drilling performance.