Which of the following is a common cause of abnormal pressure?

Abnormal pressure typically arises when the conditions within a geological formation do not allow for the normal dissipation of pressure. Under compacted shale, the failure to adequately compact leads to an excess of pore pressures because the weight of the overlying sediments is not sufficient to compress the pore fluids within the shale layer. This results in trapped fluids that contribute to abnormal pressure conditions.

In contrast, highly porous rock layers, high temperature gradients, and surface water accumulation are less likely to be direct causes of abnormal pressure in the context of well control. Highly porous rocks may facilitate fluid flow, reducing pressure build-up, while high temperature gradients can affect fluid properties but do not directly contribute to pressure abnormalities. Surface water accumulation typically influences surface water pressure and is not directly linked to underground well pressures or reservoir characteristics that lead to abnormal pressure scenarios.