Analytical Model Estimates Flow Rate and Total Discharge in Gas-Well Blowouts

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Despite multitier safeguards, blowouts occur. When such accidents happen, rate estimation is an important and daunting task. This study presents an analytical model coupling the flow in a reservoir/wellbore system of a gas well. The model considers flow in the tubing, annulus, and riser and the attendant heat transfer. To gauge safety concerns, plume dispersion is modeled under various wind-speed scenarios when ignition sources are not present. In the event of ignition, the energy of the explosion is estimated with an empirical method.

Introduction

The main purpose of this investigation is to assess the coupled nature of transient fluid flow in the reservoir and the combined fluid and heat flows in the wellbore. To that end, a coupled reservoir/wellbore analytical model was developed, which was then validated with field examples. In addition, this study attempts to address issues related to dispersion of the blowout plume and the explosion hazard that the gas poses.

Model Development

When a blowout happens, the formation fluid comes into the surroundings through the wellbore without any control and, in the meantime, the reservoir pressure declines because of depletion of the reservoir. To understand the blowout mechanism, the authors split the blowout model into three parts—reservoir, wellbore, and their interaction.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 170274, “Flow-Rate and Total-Discharge Estimations in Gas-Well Blowouts,” by R. Liu, A.R. Hasan, SPE, and S. Mannan, Texas A&M University, and C.S. Kabir, SPE, Hess, prepared for the 2014 SPE Deepwater Drilling and Completions Conference, Galveston, Texas, USA, 10–11 September. The paper has not been peer reviewed.
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Analytical Model Estimates Flow Rate and Total Discharge in Gas-Well Blowouts

14 December 2015

Volume: 68 | Issue: 1

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