Exhibit 10.18

                      [LETTERHEAD OF ZYDECO ENERGY, INC.]



                                April 28, 1997



Cheniere Energy Operating Company, Inc.
237 Park Avenue, Suite 2100
New York, NY 10017

                         Re:  Fifth Amendment to Exploration Agreement dated
                              April 4, 1996 between Zydeco Exploration, Inc. and
                              FX Energy, Inc.



Gentlemen:


In accordance with the provisions of Section 16.b of the captioned Agreement and
when accepted by you in the manner hereinafter provided, this letter shall
constitute our agreement to amend said document to provide for expansion of the
Area of Mutual Interest as stipulated in Section 14 thereof and depicted on
Exhibit "B" attached thereto as follows, to wit:


   The Area of Mutual Interest is hereby expanded to include those Block within
   the area of 3-D seismic coverage acquired by Zydeco Exploration, Inc. from
   Fairfield Industries Inc. by Supplement Agreement No. 1 to Master License
   Agreement dated January 9, 1997, lying or being situated outside of the
   existing AMI, and being Blocks 24, 25, 40, 41, 42, 43, 44, and 45, West
   Cameron Area, Offshore Louisiana.


Except as herein specifically amended, all other provisions of the captioned
Agreement shall remain unchanged.  If you are in agreement with the foregoing,
please so indicated by signing and returning the attached copy of this letter
for completion of our files.


                                           Very truly yours,


 
                                           John O. Smith
                                           President & Chief Operating Officer

ACCEPTED AND AGREED TO
THIS 28 DAY OF APRIL, 1997.
     --        -----       

CHENIERE ENERGY OPERATING COMPANY, INC.

BY: /s/ Walter L. Williams
    -----------------------      
    WALTER L. WILLIAMS

TITLE:  VICE CHAIRMAN

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