Abstract
Defoamers and antifoams are crucial components in many processes of the oil and gas industry. In particular, they play a vital role in well cementing where many additives would otherwise contribute to foam formation and air entrapment during the mixing of the cement slurry. If not controlled, foam can cause serious problems such as pump cavitation, undesired slurry densities, inadequate mixing and gas permeability issues. Quest for high performance defoaming agents has been intensified in recent years due to the challenging industry standards and new environmental regulations such as those for offshore drilling and completion operations. The major task is to find suitable additives that pose little to no risk to the environment without compromising the performance and system integrity.
Quantification of defoaming performance is critical to achieve success in cementing operations as well as in the development of new and environmentally friendly defoamers. Most commonly, defoamers for cementing operations are appraised by non-standard or traditional test methods such as blender and sparge tests. While these methods are simple to perform, they often show poor reproducibility, lack of objectivity, and do not accurately replicate field conditions. This paper presents a unique test method using a dynamic foam analyzer which is capable of characterizing defoamer performance based on fluid density during simulated mixing operations. The dynamic foam analyzer generates objective data that shows initial and persistent defoamer effectiveness. This enables more accurate dosage comparisons in the lab resulting in more controllable operations in the field.
In addition, non-silicone based defoamers are desirable due to increasingly strict environmental regulations. The current challenge is to develop green alternatives while maintaining or improving the current performance levels of the defoamers used. This paper presents an innovative approach for evaluations of cement defoamers using a unique laboratory setup and a modified blender foam test method that provide more insights into cement foaming and defoaming processes. A mechanism is proposed for action of common cement additives as foam stabilizing agents. Performance of a green non-silicone based cement defoamer was evlauted to elucidate viability of the dynamic foam analyzer in comparison to the new blender foam test method.
