Gravel-pack (GP) completions are used on formations presenting sand-production problems worldwide. The inherent problem with this type of completion is its tendency to become plugged as a result of fines migration, solids invasion, and emulsion problems, which are the most commonly damaged mechanisms affecting productivity. Pumping acid systems is an effective method to solve GP plugging problems but usually results in increased post-treatment water production. Acid will enter zones with higher water saturations, which often are higher permeability, and causes operational problems, such as decreased oil production and increased lifting costs. Historically, various methods for diverting fluids have been used. These methods included the use of viscous fluids, degradable particles, ball sealants and foam. Recently, relative permeability modifiers (RPM) have been used successfully as a diversion system for acid systems to decrease the relative permeability to water. Customized application to clean up GP completions is the presented solution. This paper describes the use of RPM diversion systems that reduce the formation's permeability to water without significant effects on permeability to hydrocarbons. Four GP wells that were treated with this system, resulting in increased hydrocarbon production without increasing water production, are presented in detail. The four wells discussed are located in the same reservoir in Oriente Basin, onshore Ecuador. Wells are placed in formation M-1 Tarapoa Oilfield, which is an unconsolidated sand formation. Sand production has occurred in some of the oil producers. Wells are generally completed with GP screens with sand being pumped to fill the perforations and the wellbore x screen annulus. Well A8 was the first well treated with the acid system diverted with an RPM. Well A8 had a production decline caused by GP plugging, which also affected the ESP equipment performance. After the treatment the well productivity was restored successfully. It was decided to treat three more wells in the same reservoir. These treatments also resulted in a gain in production. Introduction Acid preferentially goes into zones with high water saturation.(Eoff et al. 2004; Eoff and Dalrymple 2003). In heterogeneous production zones where matrix stimulation treatments are normally carried out, the acid tends to enter the area of greatest permeability and leaves the less permeable areas untreated. In this scenario, the water cut increases over time because water travels more easily through the more-permeable water zones. Faced with this problem and the necessity to remove the formation damage in the gravel pack (Schmidt 1996) small volumes of acid without diverters were pumped in an attempt to penetrate only a few inches. Following stimulation, the Productivity Index (PI) increased, partially by increasing the bottomhole pressure but mainly by significant increase in water production. Different types of diverters were later tested to reverse these results. The forms or methods of diversion of fluid wereViscous fluidsDegradableparticlesBall sealantsFoams All these methods have advantages as well as disadvantages, but it is important to mention that none of them were guaranteed not to stimulate the water areas.