Critical Gas Velocity Mapping to Predict Liquid Loading
Jagmit Singh
Dr. Rosmer Brito
Colorado School of Mines
Abstract
Objective
This paper presents a case study to predict critical gas velocity using critical velocity maps developed using Film Reversal criteria (Brito 2015). These maps were developed to determine production status (loaded or unloaded) of a single well or an entire field of wells.
Methods, Procedures, Process
The field data for 30 horizontal gas wells was analyzed. In order to simplify film reversal model calculations, parameters affecting liquid loading onset such as liquid density, flowrate and viscosity, interfacial tension, inner diameter and inclination angle were combined to calculate a new dimensionless number (X). Then, critical gas velocity maps were created for different sets of pressures, liquid flowrates and inclination angles by plotting critical gas velocity on the y-axis and the dimensionless variable X on the x-axis. Based on the current well production and fluid properties, the actual gas velocity and the corresponding ‘X‘ value point was located on the map. This point was compared to the critical gas velocity point for the corresponding liquid flowrate and ‘X’ value to determine if the well is loaded or not.
Results, Observations, Conclusions
The maps obtained showed a downward progression in velocity as the pressures increased. This is consistent with liquid loading theory and field observations. Field applicability of these maps was demonstrated for two different scenarios – single well analysis and analysis of an entire field of wells. To determine the production status of a single well at a given depth, critical gas velocity calculations were run for the entire life of the well. The results for different times were plotted on the same map and it could be seen at what point in the life of the well does liquid loading onset occur at that particular depth. The maps were also used to determine the production status of different wells in a field at a given time. Similar process as for single well analysis was used to determine which wells were loaded and which were not. These field applicability scenarios demonstrate the practicality of such maps. They provide the engineer and field operator with an easy visual of the status of the well or the field, which can be used to determine which wells are priorities in terms of applying production strategies.
Additive Information to Literature
The presented Critical Gas Velocity maps provide a practical application of the Film Reversal Model (2015). Since more inclined wells are being drilled and produced from than before, there is a need for simpler techniques to determine the liquid loading onset