A Computational XFEM Hydraulic Fracture Model for Analyzing Caprock Breach in Layered Formations

A critical challenge in CO2 storage operations is controlling and predicting vertical fracture growth resulting from CO2injection.Geologicalformationsconsist oflayerswhere eachhasvaryingmechanicalpropertiesandin-situstressfields,creating contrast between thelayers.Whenanunwantedhydraulic fracture encountersweakorstrongcaprocks,thepropagationcharacteristics are affecteddue to the non-localcharacterof a hydraulic fracture influencingthe pressure and associated fracture geometry.In this work,we employanXFEM in a fully coupledhydro-mechanicalframework toanalyze a verticalfluid-drivenfracturebreachingthe caprock.Thefracture isdriven in a multi-layerand permeable formationsbyinjectinganincompressible viscousfluid atthefracture inlet assumingthat thefracture propagatesunderplane strain conditions.Fluid flowin the fracture ismodeled by lubricationtheory and theporefluid movementin the porousformationsisbasedon the Darcylaw.Thecouplingfollowsthe Biot theory while fracture propagation criterionisbased oncohesive damagemechanics.The investigationisperformednumerically with Abaqusto obtain the fracture opening, length, and propagation pressure versus time and length. The unwanted hydraulic fracture was successfully validated against the k-dominated regime with zero leak-off. Results showed that caprock breach produces wider profiles in soft evaporitesand narrowerin hardshales.Also,the pressure profilesincreasein bothcaseswhenthe fracture penetrates the caprock.