Corrosion inhibitors, scale inhibitors, biocides, demulsifiers and wax/paraffin dispersant are typically not pure chemicals. Many of the ingredients that are used for the formulation of oilfield chemicals are side stream products having some degree of variation from batch to batch. These chemicals undergo a multitude of laboratory and field tests before they can be injected in the producing field.
The user investment in time and money to select the right chemical does not stop after the selection of the best chemical. A follow-up need to be done to insure that the chemical tested is the same as the one delivered to the field every time it is purchased. Decrease in the effectiveness of the chemical may usually seen fairly rapidly if the demulsifier’s components are different. However, if the chemistry of a corrosion inhibitor or a scale inhibitor changes without the knowledge of the user, it may go unnoticed until a catastrophic failure or the need to do an expensive workover arises. Thus, a good chemical quality control program is needed to prevent such problems.
Quality control by the user are usually based upon characteristics such as color, non-volatile residue, base number, acid number, viscosity, density, pour point and other physical parameters. However, these properties are not directly related to the composition of the actual chemical. Advanced quality control such as Fourier-Transform Infrared Spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance (C13 NMR) spectroscopy are more appropriate in determining if the chemical components and content of the oilfield chemical is different from the sample tested.