Integrated Approach: Perforation System Optimization for Sand Prevention
Authors: Ruslan Mohd Zahirin , Frydman Marcelo , Garcia German , Benavides Marcia , Sepulveda Willem , Arevalo Alejandro Matulevich 
Published: January 2010

Managing sand production is critical in brownfield operation. Solid productions are often causing issues with completion and surface facilities. Sand management and prevention are the current practices and leaving sand control as the last option if required. To make better informed decision to select sand control, one must understand, managing and preventing two conditions that may cause sand production: formation failure and sand transportation which lead to this study. The integrated approach started from technical screening of available sand control methods, followed by statistical and Monte Carlo process, geomechanics analysis, dual packer formation tester, identification of sand production prone layers, perforation system optimization and pilot wells evaluation. Technical feasibility of sand management and prevention was evaluated using Bayesian knowledge engine and extensive historical case based reasoning. All the producers with sand problems were selected for a statistical analysis to correlate the production characteristics with sand production behaviours. Significant correlation was observed for the velocity per perforation with the severity of sand production trend. Sand production is less with reduction in the velocity per perforation.

The velocity threshold limit was identified using a dual packer formation tester. Utilizing Monte Carlo probabilistic analysis and considering the variation in reservoir properties, the probable threshold limits were identified for different reservoir within the same field and area. Combining these limits with previous statistical analysis results, for this field those wells that producing higher than the medium limit historically quadruples in the sand production.

In order to address the heterogeneity of the reservoir, a sand production prediction log was created. This log combines the mechanical earth model, geology and velocity at each perforation versus velocity threshold limit for sand transportation. This gives a complete integrated insight understanding of sand production across each perforation interval. Briefly, the log will indicate if there is possibility of sand production. The log was tested with the existing wells. Sand production was observed at surface exactly as the log interpretation.

The optimum perforation system was evaluated using one of the commercialized software. The selection criteria and constraint were strongly governed by the mechanical earth model, mud invasion analysis, well productivity, sand transportation velocity threshold limit, decision risk analysis and economic evaluations. All perforation systems velocity profiles were evaluated with sand production prediction log mentioned earlier. This aid tool enables layer by layer perforation system optimization to manage potential sand production problem and guideline for production optimization processes.

This paper discusses integrated approach for sand management prevention. Case study shows 2 pilots were selected for this project using the above mentioned approached. The results are favourable,