TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOften, the main challenge in producing hydrocarbons in north Mexico is the accompanying large associated water production. In the Cuenca de Burgos field in northern Mexico, operators typically encounter water production of over 400 BWPD following fracture-stimulation treatments. This paper discusses how water production in those fields was significantly reduced using a new conformance-whilefracturing (CWF) method that incorporates a chemical relative permeability modifier (RPM) prepad.The formations were reported to have high watersaturation levels. Fracture-stimulation treatments performed in similar intervals usually (1) intersected a stringer of water within the targeted interval, or (2) extended into the highly saturated areas above and/or below the interval. Water cuts as high as 50 to 60% had made production of such intervals uneconomical.Data gathered from the first six months of production on more than seven wells in northern Mexico illustrate the economic benefit of the stimulation treatments using the new CWF technique. In many cases, the treatment has limited water production to less than 20%, and some applications have reduced water production to negligible levels. This paper discusses the job design, field application, and results of several CWF treatments performed in this area between 2004 and 2005.