The 2012 year-end total net proved crude oil reserves estimate, adjusted for the sale of BPZ Energy's 49% interest in Block Z-1 to Pacific Rubiales, is 16.4 million barrels covering the Company's Corvina and Albacora fields. The estimates were prepared by the Company's independent reserve auditors Netherland Sewell & Associates, Inc. A full presentation of our reserves estimated in accordance with Securities and Exchange Commission rules will be included in our annual report on Form 10-K.
The Company's proved (P1), probable (P2), and possible (P3) crude oil reserves on a net basis for the Corvina and Albacora fields as of December 31, 2012 were as follows:
| Total Oil Reserves (Mmbo)
|| Total Combined
| Proved (P1)
| Probable (P2)
| Possible (P3)
The following comparison of Block Z-1 reserves is adjusted for BPZ Energy's 51% interest on a year-to-year basis.
Total net proved reserves were lower in 2012 compared to 2011 levels by 1.3 million barrels of oil. Net oil production of 0.6 million barrels during calendar 2012 accounted for almost half of the decrease. The remainder of the proved reserve decrease was mainly due to workovers pending on the 14D and 15D wells at the Corvina CX-11 platform, as well as removal of the Albacora A12F well from the proved category given its required conversion to a gas injection well. During 2012 no new wells were drilled in either field.
The net probable reserves category declined by 1.7 million, also mainly due to the workovers pending at the 14D and 15D wells previously mentioned. Net possible reserves were relatively flat year-over-year.