Many shallow gas systems in North America experience a large decline in production with
time. Flow rates are often low and liquid residence times are long in such systems. A new
time-released, encapsulated product has been developed for such systems. Residence time
distribution functions are often used to understand reactant conversion in non-ideal reactors
and it is believed that their use in understanding the transport of chemicals can be applicable
in corrosion control of slow moving systems. There are many parameters that affect the
deliverability, effectiveness and control of the time-release of products in an oilfield system.
One factor is the diffusion of inhibitor within the polymer matrix (i.e. pellet). This can be
controlled by particle size. Other factors are related to the mass transfer to an external fluid
phase and the intrinsic residence time of fluids within the system. Some factors can be
controlled by the design of the product while others are controlled by the system conditions. In
many pipeline-gathering systems for sour gas, the residence time of fluids is relatively long. In
this presentation, the factors controlling time release of the product are discussed. Laboratory
results on product release are best fit to an appropriate diffusion-mass transfer model of the
product. A residence-time distribution model for an existing field in Canada is developed
based on the best fit of an earlier field trial. The residence-time distribution with a model of time
release of a newly developed product has been used to predict the time release in a field trial.
The predictions and the actual experimental results of the field trial will be compared in
different systems in terms of long-term inhibitor release profile.
Keywords: Encapsulated corrosion inhibitor, pipeline-gathering systems, low flow