structural trap

A structural trap in geology is a formation that prevents petroleum and natural gas from escaping, causing them to accumulate in a reservoir. These traps are created by tectonic events like folding or faulting of rock layers.1

The most common type is an anticline, which is an upfold in rock strata. About 80% of the world's petroleum is found in anticlinal traps. Another type is a fault trap, where rock fractures and displacement along a fault line create a barrier to petroleum migration. Salt domes can also form structural traps. These occur when upward-moving salt masses create folds or faults in surrounding rock layers.12

A crucial element of any trap is a porous and permeable reservoir rock sealed above by an impermeable cap rock, such as shale or evaporites.1