Deep Transient Testing Enhanced by Real Time Wellbore Dynamic Simulations

Abstract

Abstract Wellbore dynamics play a crucial role in reservoir testing, serving as a crucial link between the reservoir and surface measurements. This research aims to tackle the challenges faced in well control and highlight the benefits of using wellbore dynamic simulation to improve the safety of formation tester (FT) sampling and deep transient tests (DTT) conducted in wells. Special attention is given to pre-job simulations and multi-parameter sensitivity analysis. The focus is on advancing our understanding of the interaction between hydrocarbons and wellbore mud during and after FT pump-out operations. Recent advancements in DTT technology allow for the pumping of larger volumes of hydrocarbons into the wellbore compared to conventional formation tester operations. During DTT, formation fluids pumped from the well mix with drilling mud from the surface in the annulus. This fluid mixture is then circulated out from the annulus to the surface during the flowing period. Understanding these procedures is crucial for ensuring well control safety. Therefore, the use of a dynamic multiphase flow simulator that considers the interactions between downhole pumped hydrocarbons and drilling fluids becomes essential to improve the accuracy of pressure simulations during DTT operations. To enhance safety in oil and gas operations, a cloud-based wellbore dynamics simulator allows for precise quantification of drilling fluid adjustments, circulation rates, hydrocarbon composition, downhole pump rates, well depth, hole diameter, overbalance pressure, and pump duration for various FT design sequences. This enables accurate forecasting of downhole well pressure and the distribution of free gas throughout the well, with adjustments made as necessary. Furthermore, scenarios with kick potential and risk mitigation strategies are explored. This paper presents 15 case studies involving different hydrocarbon types and overbalance scenarios, where cloud-based wellbore fluid simulations were conducted for various flow rate scenarios to predict potential well control situations. Special attention is given to near-critical hydrocarbon fluids such as condensate, volatile oil, and wet gas.