X0101 EFFECT 33 LIVE 2011-05-02 09:15:00

S-4

0001346980 Chaparral Energy, Inc. 333-173516 0001364760 Chaparral Real Estate, L.L.C. 333-173516-09 0001364763 Chaparral Resources, L.L.C. 333-173516-08 0001364759 Chaparral CO2, L.L.C. 333-173516-07 0001364757 Chaparral Energy, L.L.C. 333-173516-06 0001364765 CEI Acquisition, L.L.C. 333-173516-05 0001382458 CEI Pipeline, L.L.C. 333-173516-04 0001408822 Green Country Supply, Inc. 333-173516-03 0001510108 Chaparral Exploration, L.L.C. 333-173516-02 0001510109 Roadrunner Drilling, L.L.C. 333-173516-01