Abstract
As discussed in the previous paper (Part 1), the Minamiaga "paraffin" is featured by a relatively large quantity of carboid and a small quantity of petrolene contents. Owing to the peculiarity of the "paraffin", special consideration should be given to prevent the "paraffin" trouble.
Laboratory experiments for deposition and inhibition of the "paraffin" were carried out on Minamiaga crude oil with available chemicals having surface activity. To mitigate the trouble, an addition of chemicals like petrolene was expected to be effective because petrolene (which was extracted from other crude oil) added to Minamiaga oil had revealed the tendency to reduce the deposition of solid. Among the 11 materials tested, two chemicals were selected. One was pour point reducer, the main component of which was alkylnaphthalene, and the other was sludge disperser, and the mixture of the two (in the ratio of two to one) showed better effect than in the case of separate application.
Following the laboratory tests, field test was run at the Minamiaga field. The well stream of Minamiaga-28W was divided into two equal flows at the well-head, then the mixture of the said two chemicals were added continuously at the rate of 300ppm to one of the streams. (There took place some intermittent interruptions due to mechanical reasons.) The none additive flow was for a blank test. The experiment lasted for 108 days in winter season. The result of the field test was favorable in spite of the interruptions of chemical addition into the crude oil.
It would be reasonable to establish a hypothesis that some kinds of alkylnaphthalene act as an inhibitor for coagulation precipitation of solid by bridging carboid with liquid oil. Consequently, the Minamiaga "paraffin" trouble should be prevented by adding the inhibitor.
