Flaring Reduction During Well Clean-up and Start-up Operations

Abstract This paper describes an approach to design the well clean-up operations by modelling the process with transient simulator. The paper will discuss the challenges with well clean-up with high volume of invaded fluid and a solution for efficient clean-up honoring all flowing and flaring limitation constraints in an environmentally sensitive area. Wellbore model was built in a software allowing a transient wellbore and near wellbore simulation during drilling and clean-up operations. It allowed to understand such a highly dynamic process by analyzing the evolution of rate, pressure and composition versus time. This technique was applied for a field where one may face challenges during the well clean-up such as well loading up with heavy fluid and high back pressure from production line. Moreover, according to government regulations flaring during production phase should be minimized as much as possible which creates another constraints with clean-up operations associated with flaring. A detailed model of clean-up dynamics allowed a radical change of well clean-up planning. A number of scenarios are evaluated in terms of uncertainty and risk and a detailed operating procedure is developed for the optimized well start-ups. Unlplanned emergency shut-down at surface is also simulated to ensure safety and restart possibilities, within the regulatory constraints imposed locally. With the confidence that the models are representative after sensitivity studies, it provides the operator with a tool to test sensitivity cases and develop operational solutions. It is then possible to suggest the most efficient process and estimate the volume of gas to be flared in a worst case scenario, an essential information to apply for flaring permission to the government. This approach is novel, and is possible through the utilization of a dynamic transient wellbore model with a near wellbore reservoir model that takes in consideration the invasion/losses and subsequent recovery of permeability during the clean-up process (Theuveny et al., 2013). With high confidence in transient models, it is possible to plan the clean-up process in an environment with large volume of invaded filtrate and high back pressure from production line which doesn't allow to flow the well at sufficient rate to properly clean the near wellbore zone. Integrated approach of simulating near wellbore and wellbore allows to accurately capture dynamics at any time of clean-up. Mitigation plans can be developed and proven through simulation before being implemented in the field.