The objective of this project is to develop a Reliability Centered Maintenance plan RCM, through Pulling operations to wells of a Marginal oil field those present a high frequency of failures at production string by sucker rod pump, swab and plunger lift. The first step was to rank the oil wells selected of the field of study through a Semi-quantitative Criticality Model “MCR” Criticality Risk Matrix and then apply the methodology RCM to wells those qualified in the Very High criticality range. The methodology proposed will allow developing a maintenance plan for the wells of Very high criticality.