Abstract

The aging of petroleum wells causes reduced reservoir pressures and increased hydrostatic head of liquid in the production tubing and flowlines. Although foamer applications to unload liquids are common in gas fields, these foamers were found to be unsuitable for oil well applications.

A research program resulted in the development of an effective Black Oil Foamer (BOF) for oil well applications with several potential benefits for producers. By reducing liquid loading in flowing wells and flowlines, the BOF can minimize slugging and increase oil & gas production. For wells that are cycling due to liquid loading, the BOF can minimize the non-productive downtime.

To meet varied field applications, the BOF needed to be effective over a wide range of crude oils. Flexibility in application methods including capillary, gas lift, subsea umbilical, or batch were also needed. Other requirements were to be thermally stable at wellbore temperatures, non-emulsifying, and not corrosive. In addition, the BOF needed to create a foam stable enough to unload liquids from a well but readily resolvable with common defoamers. This paper will discuss three successful, deepwater BOF field applications in the Gulf of Mexico. In all three cases, slugging was reduced with enhanced oil production, and without issues of oil/water separation or emulsification.

Introduction

Throughout the life cycle of oil and gas wells, there is a reduction in the bottom hole pressure (BHP) over time. This reduction in BHP can cause liquid loading in the production tubing and flowline and result in increased hydrostatic pressure and a lower production rate. Without the application of deliquification technologies to lower hydrostatic pressure, the production rate typically declines much more quickly than the natural decline curve, and premature ceasing of production can occur. Consequently, deliquification technologies are frequently applied to these wells to reduce hydrostatic pressure. This application can enable these wells to reach the natural decline level and experience increased production. Commonly used deliquification technologies include gas lift, plunger lift, electrical submersible pumps (ESP), and foamers (Dunning et al., 1961). Because foamers are flexible in their method of application and relatively economical, foamers have become a commonly used deliquification method for increasing production in gas fields.

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