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The ''core catcher'', the device that holds the core in the barrel, is tailored to the type of inner barrel and lithology expected. Table 2 lists core catchers by their common names and usages. In some cases, multiple catchers are used. Friable sandstone interbeddded with shale might require both slip and flapper type catchers. Full-closure catchers, run primarily to ensure success when coring unconsolidated sand, also incorporate split ring or slip type catchers to improve core recovery in the event that coring ends in hard rock.

The ''core catcher'', the device that holds the core in the barrel, is tailored to the type of inner barrel and lithology expected. Table 2 lists core catchers by their common names and usages. In some cases, multiple catchers are used. Friable [[sandstone]] interbeddded with shale might require both slip and flapper type catchers. Full-closure catchers, run primarily to ensure success when coring unconsolidated sand, also incorporate split ring or slip type catchers to improve core recovery in the event that coring ends in hard rock.

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A heavy duty core barrel should be considered when cutting long lengths of relatively homogeneous formations or when anticipating higher than normal torque loads. This system can also be especially attractive when rig time is the largest component of the coring expense.

A heavy duty core barrel should be considered when cutting long lengths of relatively homogeneous formations or when anticipating higher than normal torque loads. This system can also be especially attractive when rig time is the largest component of the coring expense.

The precursor of today's heavy duty core barrels is the marine core barrel. This tool was developed to be stronger than conventional systems for use in offshore settings. The marine barrel increases the margin of safety against tool failure, but is restricted to cutting a 3-in.-diameter core.

The precursor of today's heavy duty core barrels is the marine core barrel. This tool was developed to be stronger than conventional systems for use in [[offshore rig|offshore]] settings. The marine barrel increases the margin of safety against tool failure, but is restricted to cutting a 3-in.-diameter core.

Today's special heavy duty core barrels have been developed to core harder than normal formations and to cut extended length cores. These tools are designed to cut cores up to 5.25 in. in diameter. Heavy duty threads allow more torque to be applied to the bit and improve the margin of safety against tool failure.

Today's special heavy duty core barrels have been developed to core harder than normal formations and to cut extended length cores. These tools are designed to cut cores up to 5.25 in. in diameter. Heavy duty threads allow more torque to be applied to the bit and improve the margin of safety against tool failure.

[[Category:Wellsite methods]]

[[Category:Wellsite methods]]