Advanced Transient Hydraulic Simulations to Safely Optimise Tripping Speeds

Abstract

Abstract There are many factors that contribute to non productive time, these include but are by no means limited to Lost circulation, formation influx, pack-offs and other stuck pipe events which cause delays, problems, lost time, and generally increase risk, and cost of the well, during drilling operations. Such situations can, sometimes, escalate into serious problems that may result in expensive and undesirable technical sidetracks. Couple this with ever more complex wells, (whether they be long horizontal sections, multi-laterals, etc), drilled in ever smaller and more challenging reservoirs, such as those which are depleted, or at high pressure and or high temperature. The modelling software offers forward-looking simulations that can be used to predict drilling problems and assess the likely effects of remedial options. During real-time monitoring, advanced monitoring and trend analysis software can use downhole conditions and mud properties to forecast hole cleaning, equivalent circulating density (ECD), and temperature changes for the next depth/time interval, based on three tightly coupled real-time dynamic models – hydraulic, mechanical and thermodynamic – that simulate wellbore condition and characterize improvement or deterioration during drilling. These models continuously assess drilling performance, borehole conditions, and associated risks based on real-time symptom detection. The solution and concept presented in this paper showcases a modelling approach which allows all of these situations to be accurately modelled in a transient setting, and then also compared and back modelled using all the available real time high frequency data. This coupled with an automated drilling control system has resulted in safe, record-breaking drilling achievements in the North Sea. The models allow updated safeguards to be applied to the drilling control system to maintain a downhole pressure within the acceptable limits of the open hole formations. It also automatically stops the movement of the drill string in case of abnormal hook loads or surface torques. Since automatic actions can be triggered in case of an unexpected situation, some standard procedures have been fully automated, including friction tests and back-reaming.