George C. Flowers

Computation of the thermodynamic properties of reactions involving minerals and queous solutions with the aid of the personal computer

Abstract A BASIC program (EQCALC) for the calculation of the thermodynamic properties of reactions involving minerals, ions, and liquid water has been developed for the personal computer. EQCALC is written in “generic” BASIC in order to be as machine independent as possible. The program runs on the IBM PC, IBM compatibles, and many other microcomputers, requiring about 84K bytes for execution. The program outputs the standard molal volume, standard molal heat capacity, standard molal enthalpy, standard molal Gibbs free energy, and the logarithm of the equilibrium constant for the reaction.

The Impact of Hurricane Andrew: Changes in the Texture and Chemistry of Barataria Estuary Bottom Sediments

ABSTRACT In 1993, approximately one year after passage of Hurricane Andrew, samples were taken from 97 locations in the Barataria estuary to determine the impact of the storm on bottom sediment texture and heavy metal content. Bottom sediments of the Barataria estuary are enriched in sand relative to other southeastern Lousiana estuaries (e.g., Lakes Pontchartrain and Maurepas). Sand content of bottom sediments is comparable to that of Perdido Bay, Alabama/Florida and other estuaries along the Mississippi-Alabama-Florida coast, but this has not always been the case. Comparison of ternary sediment diagrams for 1969 and 1993 indicates that bottom sediment sand content has increased over the past 24 years. In 1969, the bottom of Barataria estuary consisted predominantly of sandy and clayey silts; presently, sand-silt-clay is the most abundant sediment type. Passage of eight hurricanes near the estuary, including Hurricane Andrew in 1992, caused the relative increase in sand content of bottom sediments. Bottom sediments of the Barataria estuary contain an average of approximately 5 moles/g acid volatile sulfide (AVS). Assuming sediment AVS is due to the presence of monosulfides, the average binding capacity of bottom sediments is approximately 5 moles divalent heavy metal/g. The Barataria estuary, therefore, has a limited capacity to absorb heavy metals via exchange reactions with sediment AVS. Heavy metal data for bottom sediments indicate that, with the exception of Ba, there has been no significant anthropogenic input of heavy metals into this estuary. Because bulk metal content is controlled largely by sediment texture, low metal concentrations are expected in a estuary containing relatively coarse-grained bottom sediments.

Middle Miocene Stratigraphic Traps, Southeast Manila Village Field, Louisiana

ABSTRACT Southeast Manila Village Field, Louisiana, produces from two middle Fleming Group sandstones at depths ranging from 11,400 to 12,000 ft. Hydrocarbon production occurs mainly by a pressure deplion mechanism; a waterflood has been initiated to stabilize reservoir pressure. Fourteen wells have been drilled to date, and ultimate recovery from the field is estimated to be 4,609 MBO and 3,267 MMCFG. Thin sand bodies, designated as the 28 and 29 Sands, occur in a shale interval, which ranges in thickness from 500 to 600 ft. The reservoir rocks are thinly laminated, moderately to well-sorted, and very fine-grained sands. Thin sand laminations have sharp lower contacts with the interbedded shales, indicating episodic deposition. Foraminiferal assemblages indicate that the sands have been deposited in 100 to 400+ ft of water. The sands are probably the result of turbidity flow deposition in a distal-delta environment. Diagenetic reactions are, in part, responsible for the hydrocarbon accumulation in the sands. Dissolution of primary calcite cement and detrital K-feldspar grains has generated secondary porosity in the sands. Precipitation of authigenic minerals, such as chlorite, pyrite, siderite, kaolinite, illite, and mixed-layer clays has, however, influenced primary and secondary oil recovery. Migration and accumulation of hydrocarbons apparently halted secondary cementation by inhibiting the precipitation of authigenic clays.

Sedimentary and Geochemical Systems in Transitional Marine Sediments in Northern Gulf of Mexico: ABSTRACT

The coastal zone of the northern Gulf of Mexico is marked by a series of bays and estuaries that serve as the principal depositional basins for rivers draining an area of greater than 160,000 km2. These rivers annually contribute a sediment load to the basins in excess of 12 million tons. Because each river drains a watershed of different lithologic character and each river is further characterized by a different flow regime and hydraulic properties, the sediments deposited in the marginal basins have unique characteristics. Extensive municipal and industrial dumping of effluent over the years has also acted to imprint geochemical differences on each of the depositional basins. Depending on the degree of industrialization within the watershed, the bays and estuaries may be described as heavily impacted (Mobile Bay), moderately impacted (Apalachicola Bay, Mississippi Sound), or slightly impacted (Pensacola Bay). A strong correlation was observed between the degree of heavy metal contamination and the textural and organic content of the sediments. Analyses further indicated that most metals were partitioned in the bottom sediments in forms that would permit their subsequent release back into the water column or would allow transference of the metal to fauna by ingestion. End_of_Article - Last_Page 1424------------