The following reconciliation of Concho’s estimated proved oil and natural gas reserves for year-end 2012 are based on reports prepared by Cawley, Gillespie & Associates, Inc. and Netherland, Sewell & Associates, Inc., independent petroleum engineers.
|Proved reserves at December 31, 2011||386.5|
|Purchase of minerals-in-place||56.5|
|Sales of minerals-in-place||(35.3||)|
|Extensions and discoveries||91.9|
|Revisions of previous estimates 1||(22.6||)|
|Proved reserves at December 31, 2012||447.2|
1 Includes 5.1 MMBoe of negative revisions due to price.
Concho’s costs incurred (including asset retirement costs) are as follows:
|Years Ended December 31,|
|Property acquisition costs||$||524,979||$||1,298,878|
|Total costs incurred for oil and natural gas properties||$||1,832,139||$||2,821,258|
For 2012, drill-bit finding and development costs, defined as the total costs incurred for oil and natural gas properties, less property acquisition costs, divided by extensions and discoveries, were $16.56 per Boe, as compared to $15.11 per Boe in 2011.