Automated Decision Support and Expert Collaboration Avoid Stuck Pipe and Improve Drilling Operations in Offshore Brazil Subsalt Well

Abstract

Offshore Brazil is a technically challenging drilling environment due to its size, depth, section length and lithology column characteristics. While drilling in this environment, operators often face nonproductive time (NPT) incidents such as stuck pipe, lost circulation, pipe failure, fishing, and plug and sidetrack. In some cases, operators are forced to sidetrack or even abandon wells after experiencing carnallite-related drilling difficulties. Drilling through carnallite is challenging because its rate of creep is eight times greater than common halite, or rock salt. Information from wells drilled through similar deep salt sections show that the salt closure rate for carnallite can reach 0.0415 in./hr (1.05 cm/hr) compared to 0.0052 in./hr .01 cm/hr) for halite. Unfortunately, NPT events repeat themselves in the course of developing a field. One of the reasons the events are not solved is that we are drowning in data. The event symptoms become lost or go unrecognized until it is too late. Early identification of symptoms as they occur while drilling in real time is critical to provide actionable information to the drilling team well ahead of the potential incident. The methods used enable the drilling team to deliver wells on plan and meet budget projections by recognizing potential drilling problems before they occur. The process integrates three key elements; 24/7 real-time surveillance, case-based reasoning software and the knowledge base of the collaboration team. These three elements combine to provide a fast, practical, real-time solution to avoid NPT. The multidisciplinary drilling optimization group, integrated with the operator's drilling team, used the automated decision support and timely collaboration for informed decisions, avoiding stuck pipe and saving rig days to free the pipe as well as potential time and cost for fishing, lost BHA and sidetrack. This paper will illustrate an efficient method of preventing drilling problems before they occur with a decision support tool that provides real-time, case-based reasoning and expert collaboration for enhanced risk assessment and hazard mitigation. The paper provides a case history using the approach taken in the drilling of pre-salt well and discusses the lessons learned during the process.