Calcium Naphthenate (CaN) formation has a major impact in some
oil production systems, sometimes causing unplanned shutdowns for days at a
time, with huge financial impact for the operating company.
Through on-site experience in troubleshooting CaN deposition
and severe emulsion problems, Oil Plus set up
a research team that developed a new laboratory screening technique to predict
the probability of sodium emulsion soaps (SES) and calcium naphthenate (CaN) deposits.
The low and high molecular weight acid concentrations along with the percentage
residue of the oil samples are compared to our extensive database, with oils
ranging from no known production problems through to the worst CaN producing
The outputs from these comparisons are called the naphthenate
probability index (NPI) and soap probability index (SPI). Whilst Oil Plus is now
confident that CaN formation can be predicted reliably, more work is required to
enable operators to plan their mitigation strategies.
This initial development work led to Oil Plus setting up two
JIP's to investigate the formation mechanism of naphthenate deposition and
produce a software prediction model to predict where, when and how much
deposition might be formed in a production system. The project involves both
academic and industrial collaborators and is sponsored by six international oil
companies and one service company.
Now in its second phase, the project has successfully developed
a method in which the variables significant to naphthenate deposition are
carefully controlled, allowing deposition to be quantified with high accuracy.
This approach of establishing solubility products, along with numerous physical
chemistry measurements, has allowed the construction of a thermodynamic computer
model controlled by inputs for all significant variables.