Solid separation from the heavy oil sludge produced from Liaohe Oilfield

Heavy oil sludge usually exists in the form of stable W/O emulsion, in which the water droplets were stabilized by natural surfactants and small solid particles. The oil recovery from the oil sludge is valuable, but the demulsification by using regular demulsifiers could be hindered by the solids. Therefore, the solid separation is important for oil recovery. In this paper, firstly, properties of heavy oil sludge produced from the Liaohe Oilfield were analyzed. Then, a multistage chemical treatment was proposed and chemicals were screened for solid separation. Limonene, sodium sulphate solution, (dioctadecyl dimethyl ammonium bromide + citric acid) were chosen for different purposes at different stages, respectively. At last, the rational separation conditions were investigated. After the treatment, the solid content in oil decreased from 18.57% to be 0.9% by mass. In addition, the mixture of recovered oil and fresh crude oil can be dehydrated easily by using regular demulsifiers.