The 15+ years of hands on experience is more valuable than you probably realize. The fact that you have had the same job for so long also shows many good points to employers-dedication, responsibility & DEPENDABILITY :-) You may not have oodles of work references but your track record with the one should pull a good deal of weight.
I know when I am looking to hire new employees I always look at how long at each job as a key factor-I need people who are dedicated to their work and not "bouncing" around. I do not want to train new employees over and over. In the long run that costs more than hiring someone who stays put :-)
Hugs
April