This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 20652, ’Field Implementation of a Real Time Drilling Problem Diagnostic for Deepwater Exploratory Wells,’ by Roni Gandelman, Alex Waldmann, Andre L. Martins, SPE, Gleber Teixeira, and Atila Aragao, Petrobras, and Mauricio Rezende and Alexandre de Mari, ESSS Scientific Software, originally prepared for the 2010 Offshore Technology Conference, Houston, 3-6 May. The paper has not been peer reviewed.
The full-length paper details the field-implementation experience of an inhouse-developed system for drilling-problems detection and identification. Starting from real-time drilling data, the system was designed to investigate reasons for deviations in important measured variables (e.g., downhole and pumping pressures, temperatures, and torque and drag) during drilling operations. Based on a hybrid approach, including multiphase-hydraulics and torque-and-drag modeling, case-history matching, and knowledge of specialists, the system should identify undesirable events.
Deep- and ultradeepwater exploratory drilling is a very risky and costly operation in which every effort to guarantee performance and operational safety is welcome. Low fracture gradients, abnormal pressures, losses, and unstable formations are among the items that make well design complex and well construction a continuous challenge.
Several exploratory prospects currently ongoing in Petrobras face very narrow operational windows, and well construction will demand unconventional techniques. The anticipation and remediation of potential hole problems is an ultimate goal of most real-time measurement devices installed on drilling rigs. Much effort has been spent in downhole sensors and data-transmission systems, but there is a common sense in the industry that very little is available in real-time data interpretation. Pressure-while-drilling (PWD) data, for instance, is used in a subjective manner, and interpretation depends to a great extent on the philosophy of the operator.
Some preliminary implementation efforts at rigsites and at onshore decision-support centers have demonstrated the potential of drilling-data-interpretation systems in reducing operational costs and risks.
In 2006, as a strategy to preserve the knowledge retained by experienced professionals and to achieve effective gains from real-time data, a development project was started to generate a drilling-interpretation system. Starting from a long-term experience in developing steady-state and transient-hydraulics models, an initial development of a real-time hydraulics model for vertical wells to guarantee pressures inside the operational window was proposed. Soon, the team understood that a reliable analysis would have to go beyond hydraulics. A multidisciplinary team, including software developers, data-communication professionals, artificial-intelligence specialists, and petroleum engineers, was established to define the requirements and objectives for the system. The idea was to make full use of measurement-while-drilling/PWD and mud-logging data for analyzing the drilling operation. Logging-while-drilling data would be considered in a further step because the company already had a team for real-time geopressure analysis.