Precipitation and Deposition: Biased Approach on Flow Assurance?

If flow assurance of hydrocarbon solids remain dominated by the chemistry of precipitation process, how about the transport phenomena that remains associated with deposition process, which remains controlled by flowrate related advective, diffusive and dispersive effects?

Why does the transport phenomena (apart from flow aspects) not deserve the required attention?

Is the synergetic effect of precipitation and deposition of solids not an integral part of the overall flow assurance investigations?

OR

Why do we have a biased approach towards ‘chemistry-dominated precipitation’ (where, chemistry remains manifested in chemical thermodynamics and solubility involving intensive properties including pressure, temperature, concentration & chemical potential), while, ‘flowrate dominated deposition’ (which remains manifested in the transport phenomena that includes mass transfer, momentum transfer and heat transfer) of hydrocarbon solids, not given the due importance?

So, in the absence of the required investigation on deposition process, is it sufficient to celebrate the following successes ‘individually’?

(a) Success of asphaltene precipitation by regular solution theory;

(b) Success of paraffin wax precipitation by chemical potential and fugacity relationships;

(c) Success of natural gas hydrate precipitation by thermodynamic modelling of equilibrium lines; and

(d) Success of naphthenate precipitation through carboxylic acid chemistry

Whether various kinds of deposition processes are required to be followed for various hydrocarbon solids as asphaltenes and naphthenate tend to precipitate resulting from pressure reduction, while, gas hydrate and paraffin wax tend to precipitate resulting from cooling, and inorganic solids tend to precipitate resulting from flashing of produced water?

Do we have the required attention on the flowrate-dominated deposition process that includes hydrocarbon solid’s mass transfer (which depends significantly on the particle diameter expressed in terms of particle relaxation time)?

Are there investigations on the deposition of hydrocarbon solids that take into account both molecular transport and particle transport, including the details that consider the factors that control the adhesion and cohesion of flow assurance deposits?

If not, focusing only on the precipitation aspects and ignoring the deposition process, then, how will we be able to contribute to the mitigation of hydrocarbon solid’s deposition and eventually, facilitate the cleaning/removal operations and work-overs?

Will fluid mechanics based flow-rate dominated deposition process would gather the required momentum, in addition to the primary focus on the chemistry dominated precipitation process?

Suresh Kumar Govindarajan

Professor [HAG]

IIT Madras 25-Dec-2024