Abstract After workover jobs, many oil-producing wells have reduced their production, which is caused by formation damage created by using inadequate completion brine. The damage mechanism may be: 1) Block in the face of the formation, produced by the tendency to form emulsions between the oil of the well and the completion brine, 2) Production of inorganic scale in the porous medium during the contact of the formation water with the completion brine, 3) blockage by suspended solids present in the completion brines, 4) Increased bacterial activity in the wellbore vicinity, 5) rock-fluid incompatibility due to sensitivity of the formation minerals to the completion brine, caused by high ion exchange, causing swelling of clays and reduction of the permeability, 6) increase of the water relative permeability. Given the above, this paper focuses on integrated analysis for selecting appropriate completion brines, based on an analysis of laboratory and production. Laboratory analysis includes: 1) Evaluation of fluid-fluid interactions, 2) physical- chemical analysis of produced water, 3) definition of Scale tendency of produced water and the mixture with control brine at the wellhead and at reservoir conditions through a simulation software, 4) filtration of the base fluid of the control brine and analysis SEM of solid waste found, 5) microbiological analysis of the base water of the completion brine, 6) compatibility brine-rock through test of core -flooding, 7) determination of critical salinity, The production analysis includes a diagnostic diagram with an assessment of the production history, fluid levels, events, extraction conditions, etc. The integrated analysis was applied in 12 wells in the fields A, and G in Colombia, to determine the root cause of production losses, after workover. The Economic evaluation showed loss of productivity, quantified in more than one million dollars per well. This paper presents the results of the evaluation in the wells G-11 and A-21, along with the conclusions and recommendations.