Oil sludge is the by-product when producing oil, mixed with water, oil, and solid sediment, which is the dangerous waste but has high recycling value. With the increasingly tense supply of oil resources, many countries are doing researches in oil sludge recycling technology. The pyrolysis technology is drawing wide attention of researchers all over the world with its advantages of disposal thoroughly and high energy recycling. The proper oil sludge treatment is essential since these waste materials are hazardous to human and environment.
In oilfield operations oily sludges are produced as sediments in tanks and apparatus, as well as from oil spills (e.g. in the course of maintenance / repair work, or due to pipeline leaks). Those sludges, in their original form, can have extremely high solids contents at moderate to high oil contents. However, at the time when the sludges from different sources are combined and prepared for treatment, the oil / water / solids ratios are such, that treatment with normal oil sludge processing equipment is easily possible. Very often oilfield sludges are collected in lagoons and withdrawn from there for processing, rather than being processed directly downstream of the source / collection point.
The differing origins and compositions of waste oil mean that its water, oil and solids content can vary considerably. A water content in the order of 40-80% by volume, approximately 10-50% by volume oil phase with rather high viscosity, and a high solids content (in the order of 10-40% by volume) with potentially very large particle sizes, as well as potential content of significant amounts of other debris often characterize this product.
Compared to many other waste oil applications, the product properties oil field sludges require special attention be given to the mechanical pre-treatment of the sludges prior to processing. And because the recovered oil is usually not refined on-site, but rather added to the crude oil stream before it is sent to refining, the oil quality is normally sufficient using 3-phase decanter technology, which means these systems can typically be designed with one single 3-phase separation step.