Effect of Shear on paraffin Inhibitor Performance: cold Finger Investigation with a GOM crude Oil

David Jennings and Klaus Weispfennig

Baker Petrolite, 12645 W. Airport Blvd., Sugar Land, TX 77478 USA

Paraffin inhibitors function by incorporating into wax deposit structures, altering the deposit structure’s ability to adhere to surfaces. Generally, effective inhibitors create weaker deposits which are susceptible to removal from shear forces in the flow field. For some crude oil production systems, paraffin inhibitors can provide significant reduction in wax deposition and be an economically attractive means for increasing production and/or decreasing wax remediation control costs.

Typically paraffin inhibitors are evaluated using simple laboratory screening devices, such as cold fingers.  In this work, a series of cold finger experiments was performed to examine the effect of shear on inhibitor performance with a Gulf of Mexico (GOM) crude oil. 

Results from the study showed that the weight percent inhibition of wax remained relatively constant with increasing shear indicating that inhibitor performance remained constant; within the shear range studied. The amount of bare cold finger surface was found to increase with increasing shear though. In contrast, the weight percent inhibition of the total deposit (deposited wax and entrained crude oil) was found to decrease with increasing shear in the study. This is, however, related more to an effect of increasing shear reducing the amount of entrained oil present in deposits rather than a reduction in inhibitor performance. Examples from several cold finger experiments will be discussed illustrating these effects.