Appeal No. 1996-2400
Application 08/245,145
reference than that shown in Example 1 thereof (5 percent by weight), with the expectation of obtaining
“maximum scale inhibition of the formation” and an “optimum concentrated sodium chloride solutions
required to carry an effective amount of inhibitor into the formation” (id.). Appellants point out that in
the method of Faircloth et al., the “precipitation [of the inhibitor] is caused by changing the pH of the
solution, and there is no suggestion that salt concentration could be adjusted . . . to obtain precipitation
of the inhibitor,” and thus submit that a prima facie case of obviousness has not been established (brief,
page 4). We agree with appellants.
We find that Faircloth et al. teaches that increase in pH to precipitate the calcium salt of the
inhibitor is accomplished by the hydrolysis of a “precursor which is capable of reacting within the
formation to become a basic component” (e.g., col. 2, lines 26-28, col. 2, line 64, to col. 3, line 48,
and col. 4, lines 6-22 and 35-57). We further find that the formation brine used by Faircloth et al. to
squeeze the acidic inhibitor solution into the formation is disclosed in the reference to be “[t]ypically . . .
slightly acidic but highly buffered due to the presence of an abundance of ionic species . . . [and] will
dissolve small quantities of the calcium-inhibitor salt” (col. 4, lines 22-30 and 51-52). Furthermore,
Faircloth et al. discloses nitrilotri(methylene phosphonic acid) and diethylenetriaminepenta(methylene
phosphonic acid) as scale inhibitors (col. 3, lines 61-67), with the latter exemplified in Faircloth et al.
Example 1.
Based on this evidence, we find no suggestion in Faircloth et al. to increase the sodium chloride
concentration above the 5% by weight of the scale inhibiting solution disclosed in Example 1 thereof.
In re Antonie, 559 F.2d 618, 619-20, 195 USPQ 6, 8-9 (CCPA 1977); see also In re O’Farrell,
853 F.2d 894, 903-04, 7 USPQ2d 1673, 1681 (Fed. Cir. 1988). To the extent that the examiner
relies on inherency with respect to the amount of sodium chloride in formation brine, we observe that
Faircloth et al. disclose that “[a]s production resumes from the wellbore, the pH of the solution will
become that of the formation brine” which are “[t]ypically . . . slightly acidic” (col. 4, lines 22-25). We
find no evidence in the record which establishes that the concentration of sodium chloride in “typical”
formation brine is such that the solution formed after production is resumed, which would be expected
to possess nitrilotri(methylene phosphonic acid) or diethylenetriaminepenta-(methylene phosphonic
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