Proved vs. Proven

The past participle of the verb “to prove” can be either proved or proven.
Webster’s dictionary says “proved or proven,” which means they are equal variants and can be used interchangeably. British writers tend to use “proved” more often, while American writers tend to use “proven” more often.

Examples:
She has proven him wrong on more than one occasion. (American)
She has proved him wrong on more than one occasion. (British)

If you are using an adjective, Webster’s dictionary says “proven” is used more often.

Examples:
Proven gas reserves
A proven method

Here’s what Merriam-Webster has to say about “Proven”:
“… gradually worked its way into standard English over the past three and a half centuries. It seems to have first become established in legal use and to have come only slowly into literary use. Tennyson was one of its earliest frequent users, probably for metrical reasons. It was disapproved by 19th century grammarians, one of whom included it in a list of ‘words that are not words.’ Surveys made some 50 or 60 years ago indicated that proved was about four times as frequent as proven. But our evidence from the last 30 or 35 years shows this no longer to be the case. As a past participle, proven is now about as frequent as proved in all contexts. As an attributive adjective (proved or proven gas reserves) proven is much more common than proved.”

Interestingly, a search on OnePetro.org, limited to the SPE Papers, showed 11,213 hits for “proven” and 19,216 hits for “proved.” As an adjective, there were 563 hits for “proved reserves” vs. 396 hits for “proven reserves.”

My conclusion: It doesn’t matter which word you use for it, as long as you abide by the SPE definitions for calculating reserves. Here’s the link:
http://www.spe.org/industry/docs/PRMS_Guidelines_Nov2011.pdf

Guidelines for Application of the Petroleum Resources Management System (PRMS).
This new, 221-page document replaces the 2001 “Guidelines for Evaluation of Reserves and Resources” with expanded content that is updated to focus on using the 2007 PRMS to classify petroleum reserves and resources.

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Profound Quote of the Day:
“As a vessel is known by the sound, whether it be cracked or not; so men are proved, by their speeches, whether they be wise or foolish.”
– Demosthenes, Greek statesman, 382–322 BC
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