Analysis of Gas Kicks in Multilateral Wells Utilizing Computer Simulation
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Multilateral well control is an issue in today's petroleum industry that has not had sufficient study to date. Many operators are drilling multilateral wells, with limited knowledge of the pressure characteristics in the multiple wellbores as well as how the pressures in the individual laterals are related. If a kick occurs in a multilateral well, the operator must be able to determine which lateral or laterals the kick is in, as well as the effect that circulation of the kick can have on the pressures in the other laterals. This paper reports the results obtained in a study that has been conducted utilizing a Multilateral Well Control Simulator developed at Seoul National University and Texas A&M University.1-3 This simulator calculates and records the pressure profiles in all laterals, on a continuous, basis during tripping, drilling, and well kill operations. From these simulations, we can determine the effect that the changing annulus pressure profile can have on all of the laterals. Depending on the relative pressure gradients of the different laterals with respect to each other, kicks can actually be induced in one lateral while circulating gas from another and as the gas enters the mother wellbore. For safe and efficient well control, the operator must have knowledge of the formation pressures in each lateral so that steps can be taken to prevent the changing annulus pressure from inducing additional kicks in the other laterals. The industry now has a study and tool which can help operators drilling multi-lateral wells to better understand how pressure changes in one lateral effect the others. This tool will allow a better understanding of the pressure changes in multiple lateral sections that will occur during well kill operations. Copyright 2006, IADC/SPE Drilling Conference.
author list (cited authors)
Schubert, J. J., Juvkam-Wold, H. C., Choe, J., & Dreher, D. T.