Exhibit
23.3
CONSENT
OF INDEPENDENT PETROLEUM ENGINEERS AND GEOLOGISTS
The
undersigned hereby consents to the references to our firm in the form and
context in which they appear in the Annual Report on Form 10-K of St. Mary Land
& Exploration Company for the year ended December 31, 2009. We
hereby further consent to the use of information contained in our reports, and
the use of our audit letter, as of December 31, 2009, relating to estimates of
revenues from St. Mary Land & Exploration Company’s oil and gas
reserves. We further consent to the incorporation by reference
thereof into this Registration Statement on Form S-8.
/s/
RYDER SCOTT COMPANY, L.P.
Ryder
Scott Company, L.P.
Denver,
Colorado
March 26,
2010