Demulsification Efficiency of Some New Stearate Esters of Ethoxylated and Propoxylated 1,8-Diamino-Octane for Water in Crude Oil Emulsions

Abstract

In this work, eight demulsifiers were prepared from 1,8-diamino-octane (DAO). The DAO was ethoxylated or propoxylated up to 100 ethylene or propylene oxide units respectively. These alkoxylated products were esterified to mono, di, tri, and tetra stearate. The chemical structure was confirmed by FTIR and nitrogen content. The surface active parameters of these surfactants were investigated on the basis of the surface tension measurements at 25°C and 60°C. These surfactants were tested as emulsion breakers (demulsifiers) against waxy crude oil emulsion (Water content (BSW) = 18%). From the obtained data, it was found that the prepared materials have surface active properties let them act as good demulsifiers. The maximum demulsification efficiency (100%) was obtained by DAOE₁₀₀-1 at 400 ppm_[30 min], the mixture of (DAOE₁₀₀-1 + DAOP₁₀₀-2) in ratio [3:1] at 400 ppm and (DAOE₁₀₀-2 + DAOP₁₀₀-1) in ratio [1:3] at 400 ppm at temperature 60°C the time taken for complete water separation was 15 and 9 minutes. for these mixtures, respectively. The flow properties of the emulsion with and without the demulsifier were investigated. The obtained results showed that the demulsifiers used enhance the dynamic viscosity and yield value (τ_B). The viscosity was reduced from 10.5 for the untreated crude oil to 3.58 for the treated crude oil at concentration 100 ppm and a temperature of 60°C, meanwhile the τ_B was reduced from 0.054 for crude oil to 0.013 for the treated sample at the same condition.

Keywords:

• Alkyldiamine
• demulsifier
• dynamic viscosity
• emulsion breakers
• surfactant
• yield value

Notes

X+Y+Z+M = 100.

e.o. = ethylene oxide.

p.o. = propylene oxide.

R = stearic acid (C₁₇H₃₅).

TCN = total carbon number in esters groups.

e.o = ethylene oxide unit.

p.o = propylene oxide unit.

n.s = no separation at any conc or time during the test.