Breaking of Water-in-Crude Oil Emulsions. 4. Estimation of the Demulsifier Surfactant Performance To Destabilize the Asphaltenes Effect

Abstract

Surfactant molecules are tested as water-in-crude emulsion breakers to attain the quickest separation rate in the so-called “proportional regime”. A concept of demulsifier performance is proposed on the basis of the required demulsifier concentration to offset the effect of a given amount of asphaltenes. The experimental evidence allows one to rank the tested products and relate their performance to their hydrophilicity and molecular weight. Some evidence indicates that the presence of acids in the crude makes it easier to break emulsions and suggests that so-called “extended surfactants” can significantly shorten the demulsifying process.

Breaking of Water-in-Crude Oil Emulsions. 6. Estimating the Demulsifier Performance at Optimum Formulation from Both the Required Dose and the Attained Instability

“…Since the simplified experimental conditions consist in, as in previous articles of this series (13,35) , a low concentration of both asphaltenes and demulsifier in the bulk oil and water phases, it may be assumed that the adsorbed A and D amounts are proportional to their concentration in the oil and water bulk phases, which is known to be the case in the initial part of almost all adsorption isotherms. In other words:…”

“…In what follows, the demulsifier dose is used to scan formulation as in two previous articles of this series 13,35 , and the stability vs C D is plotted, C D * being the value at which the minimum stability is reached, i.e. the optimum formulation.…”

“…As in the previous articles of this series 12,13,35 , the conditions are selected so as to focus on the formulation influence and to reduce secondary effects: (1) the demulsifier is placed in the aqueous phase before emulsifying so that the demulsifier convection and diffusion through oil is eliminated;…”

“…what is referred to as 'stability' in the plots, is the time required for the separation of half of the water, i.e. 2.5 ml, as used in previous reports 13,35,50 after optimization 17,51 . Hamaca crude oil is an extra heavy one, i.e.…”

Study of the formation and breaking of extra-heavy-crude-oil-in-water emulsions—A proposed strategy for transporting extra heavy crude oils

“…crude composition, brine and temperature) must be controlled to obtain the optimal formulation of new demulsfiers and it is difficult to found the compromise between parameters to obtain the best conditions to break the emulsion in practice [29][30][31][32][33].…”