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Financial Information: Reserves/Production Indices

  1. Proved reserves are calculated in accordance with U.S. Security Exchange Commission (SEC) rules.
  2. Probable reserves 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 regulations.
  3. In regard to the proved reserves and probable reserves, the reserves of the projects which are expected to be invested a large amount and affect the company' future result materially are evaluated by DeGolyer & MacNaughton, and the others are done internally.
  • 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 / The sum of proved reserve extensions, acquisitions and revisions.
  • Exploration success ratio = The number of net productive exploratory wells drilled / 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.

↓This table is scrollable horizontally.

Years ended March 31 2014 2015 2016 2017 2018
Net proved reserves (MM boe) 2,532 2,434 3,264 3,304 3,857
Net probable reserves (MM boe) 1,945 1,610 1,705 1,389 1,459
Net production (Thousand boe/day) 409 408 514 521 450
Reserves to production ratio (Years)          
Proved reserves 17.1 16.4 17.4 17.4 23.5
Proved reserves + Probable reserves 30.2 27.2 26.4 24.7 32.4
Reserve replacement ratio (3-year average, %)* 370 100 321 246 362
Average expenses per boe produced (US$)          
Production cost 18.3 17.8 12.6 11.2 12.8
Production cost (Excluding royalty) 9.8 11.2 7.8 6.1 5.9
Selling, general and administrative expenses 3.5 3.5 2.6 2.1 2.7
Finding and development cost per boe
(3-year average US$)
11.7 58.2 16.9 15.7 7.7
Exploration success ratio (3-year average, %) 59.5 52.9 45.3 43.8 21.0
* Lower ratio in 2015 resulted from the absence of the positive impact from newly booked proved reserves of the Ichthys LNG project in 2012. Higher ratio in 2016 resulted from the acquisition of producing ADCO Onshore Concession in Abu Dhabi, and others.

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