Abnormal fluid pressures caused by deposition and erosion of sedimentary basins
Gravitational loading or unloading due to deposition or erosion in sedimentary basins is one of the most common mechanisms responsible for abnormal fluid pressures in geologic formations. This paper examines the integrated response of fluid pressures to both deposition and erosion using vertical one-dimensional numerical models. The modeling results show that vertical loading and unloading of sedimentary basins containing thick interbeds of low permeability can give rise to abnormal fluid pressure-depth trends that closely resemble those observed in the field. On a geological time scale, an under-pressured formation may become normally pressured or over-pressured and vice versa because of transient flow induced by vertical geologic movements. A case study in the Guymon area of Texas County, Oklahoma, shows that there are two underpressured reservoirs in this area. The burial curve constructed from geologic information indicates that this area has undergone multiple subsidence and uplift events. Based on stratigraphic information, a vertical geologic section of this area is represented by a numerical model consisting of two reservoir formations and two shale (confining) units. The numerical model is able to reproduce the observed pressure abnormalities based on the drill-stem test (DST) data. The hydraulic conductivities of the two shale formations are estimated to be 4.2 × 10 and 5.1× 10 m s from model calibration.q 1998 Elsevier Science B.V.
On the Maintenance of Anomalous Fluid Pressures: I. Thick Sedimentary Sequences
Various physical and chemical processes may be envisioned which will cause anomalous pressures on an underground fluid. In order to consider the maintenance of anomalous pressure, it is necessary to consider the problem as one of nonsteady fluid flow. The time rate of pressure change and maintenance depends upon the hydrodynamics of flow through porous media and the particular boundary conditions. This paper presents a series of general solutions to hydrodynamic models which are germane to the problem of creating and maintaining excess-fluid pressures in a thick sedimentary sequence.

The creation and maintenance of fluid pressures approaching lithostatic pressure through a process of continuous sedimentation was evaluated. Our results indicate that a sedimentation rate of 500 m/106 yr (reasonable for the Gulf Coast) will create fluid pressures approaching lithostatic in a sedimentary column that has a hydraulic conductivity of 10−8 cm sec−1, or lower.

It is apparent that the creation of anomalous pressure and its maintenance depends, to a large degree, upon the hydraulic conductivity and, to a lesser extent, upon the specific storage of clay layers within the system.
Fortune and Responsibility in Calderón's La gran Cenobia
La gran Cenobia deals with the war between Queen Zenobia of Palmyra and the Emperor Aurelian. Calderón de la Barca draws most of his information from historical sources; the dramatist, however, changes history and adapts it to his own dramatic purpose. The theme of Fortune gives unity to the play. Aureliano is portrayed as a tyrant who, to prove his independence from Fortune, behaves tyrannically, causing his eventual downfall. Cenobia believes that Fortune controls her life, but does not acknowledge that her own actions contribute to her misfortune. The analysis concludes that Fortune, as depicted in this play, is not an omnipotent and blind force, but what one has forged with his or her own actions coupled with the actions of others and circumstance.