EXHIBIT 23.1

CONSENT OF INDEPENDENT PETROLEUM ENGINEERS AND GEOLOGISTS

     Netherland, Sewell & Associates, Inc. has issued a report, as of December 31, 2006, of the “Estimate of Reserves and Future Revenue to the Ultra Petroleum Corporation Interest in certain oil and gas properties prepared in accordance with Securities and Exchange Commission guidelines” for Ultra Petroleum Corp. Netherland, Sewell & Associates, Inc. consents to the reference in Form 10-K to Netherland, Sewell & Associates, Inc.’s reserve report dated January 30, 2007, and to the incorporation by reference of our Firm’s name and report into Ultra’s previously filed Registration Statements on Form S-8 (File Nos. 333-132443; 333-13342; 333-13278) and Form S-3 (File No. 333-89522).

NETHERLAND, SEWELL & ASSOCIATES, INC.
By:	/s/ Frederic D. Sewell
	Frederic D. Sewell
	Chairman and Chief Executive Officer

Dallas, Texas
February 20, 2007