Reserves/Rroduction Indices | INPEX CORPORATION

Net proved reserves, Net probable reserves

In the year ended March 31, 2010, the total of our proven reserves and prospecting reserves fell 8% compared with the previous fiscal year to approximately 4.4 billion barrels. Only slight additions were made through such means as discovery of new oil and gas fields, while production during the period declined.

Reserve to production ratio (Proved reserves,Proved + Probable reserves)

Reserve replacement ratio (3-year average)

Average expenses per boe produced (Production cost, General and administrative expenses)

Finding and development cost per boe (3-year average)

Exploration success ratio (3-year average)

Note:

Proved reserves and production volumes are calculated in accordance with U.S. Security Exchange Commission (SEC) rules.
Probable reserves as of March 31, 2008,2009 and 2010 are calculated in accordance with SPE/WPC/AAPG/SPEE guideline (SPE-PRMS) approved in March 2007. The volumes are sum of proved reserves and probable reserves by SPE - PRMS after deduction of proved reserves by SEC rules. Probable reserves as of March 31, 2007 is based on guideline established by SPE and WPC (1997 SPE/WPC).
Proved reserves and probable reserves are based on the reserves report by DeGolyer and MacNaughton. Reserve volumes of Joslyn oil sand project (mining) are based on the evaluation by RYDER SCOTT as of March 31, 2008 only.

Reserves to production ratio (Years) = Reserves as of the end of the fiscal year / Production in the fiscal year
Reserve replacement ratio = Proved reserves increase including acquisition / production
Finding and development cost per boe = The sum of total costs incurred, for exploration and development of oil and gas fields and total costs incurred for acquisitions divided by the sum of proved reserve extensions, acquisitions and revisions.
Exploration success ratio = The number of net productive exploratory Wells drilled divided by the number of net exploratory Wells drilled
Exploratory well：An exploratory well is a well drilled to find a new field, to find a new reservoir in a field previously found to be productive of oil or gas in another reservoir or to extend the limits of a known reservoir.

Years ended March 31	2007	2008	2009	2010
Net proved reserves (MM boe)	1,770	1,645	1,598	1,475
Net probable reserves (MM boe)	1,959	2,721	3,176	2,929
Net production (M boe/day)	418	423	405	405
Reserves to production ratio (Years)
Proved reserves	11.6	10.7	10.8	10.0
Proved reserves + Probable reserves	24.5	28.2	32.3	29.8
Reserve replacement ratio (3-year average, %)*1	293%	122%	61%	35%
Average expenses per boe produced (US$)*2
Production cost	8.5	10.2	12.4	11.2
Selling, general and administrative expenses	1.7	1.6	2.5	2.7
Finding and development cost per boe (3-year average US$)*2,3	6.9	17.5	28.3	55.4
Exploration success ratio (3-year average, %)	32.8%	57.9%	56.3%	64.5%

*1	Higher ratio in 2009 and 2010 resulted from no substantial addition to the proved reserves.
*2	Figures are translated into U.S.dollars based on the average exchange of the relevant fiscal year. In the fiscal years ended March 31, 2007, 2008, 2009 and 2010 the average exchange rate were ¥116.62, ¥113.61, ¥100.85 and ¥92.49 respectively.
*3	Higher costs in 2008, 2009 and 2010 resulted from no substantial addition to the proved reserves and increased exploration and development expenditures during the term.

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