Abstract
The presence of solids in the hydrocarbon treatment and separation equipment downstream the choke can have a great impact on the process operability, assets risks, flow assurance, thus on the economics of the operation. It has been well documented that solids can highly stabilize emulsions, sometimes even better than surfactants. In fact, solids can be attached to the oil/water interface in an almost irreversible way that impedes droplets coalescence mainly by steric repulsion. Moreover, naturally surfactant molecules present in the crude oil (e.g., asphaltenes, naphthenic acids, resins, carboxylic acids) or production chemicals (e.g., anticorrosion, antiscales, demulsifiers, antifoamers) can enhance the ability of solids to promote emulsification and emulsion stability. In addition, the interaction of chemical EOR with the produced solids can lead to production issues like wellbore blockage, emulsion stabilization, increase of waste streams, equipment clogging, and so on.
In this work, the impact of solid particles on oil/water separator (i.e., emulsion stability) and on the produced water treatment has been studied. On the one hand, the impact of the solid concentration has been evaluated through rapid emulsification tests founding that, as a general trend, the increase of the solid concentration led to more stable emulsions. The impact of the presence of polymer (Xanthan) has also been tested through bottle testing. The interaction between the solids, the polymer, the demulsifier, and the fluids is quite complex as their presence either has no impact or hinders separation. Furthermore, the solid partitioning between both phases depends on their size and wettability, leading in some cases to the formation of rag layers. On the other hand, the impact of these solids on different techniques of water treatment in presence of polymer has also been evaluated such as water clarification (gravity settling) in presence of water clarifiers or dead-end filtration. In the first case, the presence of solids enhanced water clarification either by enhancing agglomeration or by increasing the droplet density. In the case of the filtration, the main factor affecting the filtration is the polymer itself while the presence of the solid particles can enhance this behavior.
