# Identifying the Enhanced Oil Recovery Polymer in Sludge Formed in Water Lines

## TL;DR

This paper introduces a method to detect EOR polymers in oil industry sludge, helping prevent formation and reduce environmental impact.

## Contribution

A novel procedure using SEC and MALS to identify EOR polymers in sludge samples is developed and validated.

## Key findings

- The developed procedure successfully detected EOR polymers in synthetic sludge samples.
- EOR polymer was detected in all eight real sludge samples from a Brazilian oil field.
- The method allows estimating polymer concentration in sludge.

## Abstract

Sludge formation is extremely undesirable in the petroleum
industry.
Such sludge formation can be induced by different causes. The deposition
of asphaltenes, waxes, inorganic salts, and even corrosion products
is among the main causes of sludge formation. Therefore, it is very
important to characterize the sludge to identify the causes of its
formation and apply procedures to minimize or even avoid it. A protocol
to characterize sludge in oil and water lines is already available.
However, the role of the polymer used in enhanced oil recovery (EOR)
on the sludge formation is already unknown. In this work, a procedure
to identify the presence of the EOR polymer in sludge samples was
developed. Two techniques to detect polymers were selected: size-exclusion
chromatography (SEC) and multiangle light scattering (MALS). These
techniques were validated by using polymer solutions at different
concentrations. Then, synthetic sludge samples were prepared based
on an emulsion of waxes and asphaltenes in toluene and brine, without
and with different concentrations of polymers. The synthetic sludge
samples were submitted to successive extractions with organic solvents
to recover the residue, which was dispersed in water, filtered, and
analyzed by SEC and MALS. The procedure was validated with synthetic
sludge and applied to eight real sludge samples coming from a Brazilian
oil field. The polymer was detected in all of them, and its concentration
could be estimated. This kind of characterization makes it possible
to identify the causes of sludge formation, preventing it and helping
to reduce the environmental impact of the oil industry.