packers

The probability of packer sticking is increased because of the casing deformation and crustation in casing failure well.

在损井中,由于形、结垢等因素,进一步加大了封隔器卡钻的可能性。

In order to prevent failure of packer and provide theoretical basis for selection of unsetting shear pin, the unsetting force of packer must he calculated in design.

为了防止封隔器在工作程中失效，并为解封剪钉（或剪环）的选择提供理论依据，必须进行解封力的设。

The causes are presented as follows: packer unloading pressure, formation damage, oil tool plugging, formation voidage, the worst formation physical properties and the effect from vicinage wells.

地层污染或工具堵塞;地层欠压;地层物性极差;邻井影响等。