Influence of n-Paraffin Composition on the Aging of Wax-Oil Gel Deposits
نویسندگان
چکیده
An excess Gibbs free energy model is applied to in®estigate the influence of n-paraffin composition on the aging beha®ior of wax-oil gel deposits known to form in subsea petroleum transport pipelines. The aging of wax-oil gels occurs by a counterdiffusion process where wax molecules with carbon numbers greater than a critical carbon num( ) ber CCN diffuse into the gel matrix, and ®ice ®ersa. Model crude oils were formulated to exhibit ®arying decreasing exponential distributions of n-paraffin components in the range n-C to n-C . Deposition experiments were conducted using a laboratory cold 9 53 finger apparatus simulating the cold wall of a subsea pipeline. Gas chromatography analysis of gel deposit compositions yielded experimental CCN ®alues. A solid-liquidphase equilibrium model, employing a modified ®ersion of UNIQUAC to compute solid-phase component acti®ity coefficients, was able to successfully predict the critical carbon number for a ®ariety of model oil n-paraffin compositions.
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