Major Customers	12 Months Ended
Dec. 31, 2012
Major Customers
Major Customers	4. Major Customers The Partnership sells crude oil and natural gas on credit terms to refiners, pipelines, marketers, and other users of petroleum commodities. Revenues are received directly from these parties or, in certain circumstances, paid to the operator of the property who disburses to the Partnership its percentage share of the revenues. During the year ended December 31, 2012, one marketer and one operator accounted for 14.4% and 79.9% of the Partnership’s crude oil and natural gas revenues, respectively. During the year ended December 31, 2011, one marketer and one operator accounted for 27.5% and 63.9% of the Partnership’s crude oil and natural gas revenues, respectively. During the year ended December 31, 2010, two marketers and one operator accounted for 20.1%, 35.5%, and 43.5% of the Partnership’s crude oil and natural gas revenues, respectively. Due to the competitive nature of the market for purchase of crude oil and natural gas, the Partnership does not believe that the loss of any particular purchaser would have a material adverse impact on the Partnership.

4. Major Customers

The Partnership sells crude oil and natural gas on credit terms to refiners, pipelines, marketers, and other users of petroleum commodities. Revenues are received directly from these parties or, in certain circumstances, paid to the operator of the property who disburses to the Partnership its percentage share of the revenues. During the year ended December 31, 2012, one marketer and one operator accounted for 14.4% and 79.9% of the Partnership’s crude oil and natural gas revenues, respectively. During the year ended December 31, 2011, one marketer and one operator accounted for 27.5% and 63.9% of the Partnership’s crude oil and natural gas revenues, respectively. During the year ended December 31, 2010, two marketers and one operator accounted for 20.1%, 35.5%, and 43.5% of the Partnership’s crude oil and natural gas revenues, respectively. Due to the competitive nature of the market for purchase of crude oil and natural gas, the Partnership does not believe that the loss of any particular purchaser would have a material adverse impact on the Partnership.