Deformation Mechanism Of Fracture In The Cap Rock And Vertical Sealing Ability

Capillary sealing ability of most of the cover layer is very strong on both the macro and the micro.Nor does it cover layer cracking due to reservoir overpressure.But cover often be discovered secondary reservoir and is most associated with the fracture.Study of deformation mechanism on fracture in the cover layer and vertical sealing ability has a certain relevance.Under certain conditions,most of the rocks will generate the brittle-ductile transition.Deformation properties of rock are influenced by many factors,with increasing confining pressure,ductile of rock increases;But,when pore pressure,temperature,fluid content and strain rate decrease,ductile of rock gradually increases.Wan Gui-mei(2008)found that salt rock began to enter the softening point at 500m depth,it can reach a very strong liquidity at 3000m depth.While gypsum,when the buried depth is more than 2000m,it will occur dehydration and turn into anhydrite.When gypsum,mud and salt layer alternating deposits,this can greatly increase ductile of salt and mud.The buried deep of gypsum-salt rock and gypsum-mudstone caprock in Kuqa depression are almost below 3000m.Therefore the cover layer have a certain degree of ductile deformation.Papers considering effect of brittle-plastic deformation of rock factors,such as temperature and confining pressure and pore fluid,strain rate,timing and anisotropic,consolidation-consolidation of mudstone in half to plastic,brittle deformation of overconsolidated rock is more likely to occur.For gypsum-salt rock,however,buried deep in a paste of 2600m above salt layer dominated by brittle easily cracke,3500m gypsum-salt layers are plastic,easy to change,3000?3200m for the transition phase.Summary out five species cover layer crisp plastic evaluation method,respectively is brittle index,and Super consolidation index,and mudstone of within friction angle,and q-p phase figure and rock density.Using the methods above to hailar--tamuchage basin has two sets of mudstone caprock evaluation,considers two sets of mudstone of the basin is in a consolidation phase,belongs to the stage of plastic deformation,caprock closed strong.and above method on hailaer--tamuchage basin of two sets mudstone cover layer for has evaluation,think the basin of two sets mudstone are is consolidation stage,belonging to plastic deformation stage,cover layer closed ability strong.