Sand Control: Sand Characterization, Failure Mechanisms, and Completion Methods

摘要

Sand production has historically been a problem associatedrnwith some consolidated, poorly consolidated, andrnunconsolidated sand formations. The result is usually lostrnproduction due to formation sand and fines plugging gravelrnpacks, screens, perforations, tubular, and surface flow linesrnor separators.rnCompletion methods applied to minimize sand productionrninclude: gravel packing, sand consolidation, criticalrnproduction rate, oriented/selective perforation, FracPacking, orrnany combination of these methods. These techniques are usedrnin consolidated, poorly consolidated, and unconsolidated sandrnformations. However, there are no guidelines available in thernliterature on how these methods are selected.rnMechanisms for sand failure include: tensile, shear,rncohesive, and pore collapse. Additionally, failure due tornchemical effects can occur when the cementation materials arernweakened due to chemical interactions. Many mathematicalrnmodels have been presented in the literature to predict sandrnfailure, and consequently determine sand production. Thesernmodels are based on different failure mechanisms and include:rnpressure drawdown/compressive strength, failure based on arngiven failure criterion such as Mohr Coulomb, cohesivernstrength failure, elastoplastic failure around a perforation,rnviscoplastic modeling, and empirical correlations. However,rnthere are no guidelines on how these models are applied basedrnon the characteristics of the sand formation.rnExperimental studies have been presented in the literaturernto model sand failure. These studies include sand arching,rnhollow cylinder strength, triaxial and hydrostatic, and largernscale testing. Laboratory testing are designed to study a givenrnfailure mechanism, and thus to predict sand production.rnThe objective of this paper is to categorize sandrnformations that potentially exhibit sand failure and sandrnproduction. Based on this characterization, an appropriaternlaboratory testing and mathematical modeling arernrecommended, and a completion method is suggested.rnExamples from standstone reservoirs in Saudi Arabia will bernused to demonstrate certain methods used for sand control.