Hannah Chambers

presents

Deposition and Diagenesis of the Blossom Sand, Panola County, Texas

12:00 PM Wednesday, April 21, 2021
on Zoom

ABSTRACT

The Late Cretaceous Blossom Sand is a sandstone within the Austin Group. In the East Texas Basin, it is a historic gas reservoir located at depths of approximately 2,000 ft. The Blossom Sand can be found in the subsurface of Arkansas, Louisiana and in outcrops of northeast Texas. Since the discovery of the Carthage Field, the Blossom Sand has produced approximately 26 BCF of gas with minor amounts of oil. Because very little research has been conducted on this sandstone, the origin of its clay minerals, and depositional style have gone largely unknown. This study provides insights into the depositional environment and diagenetic history of the Blossom Sand using thin section analysis, x-ray diffraction, x-ray fluorescence, scanning electron microscopy, and porosity and permeability measurements. Each method was used to identify clay minerals and their associations and variability, and correlated with porosity/permeability throughout the core to determine controls.

The major minerals found in this formation include quartz, calcite, and illite. The Blossom Sand is composed of two major sand facies that contain planar lamination, wavy bedding, bioturbation, pellets, and casts and molds of shallow marine bivalve organisms. Porosity and permeability are inversely correlated with calcite content based upon Ca concentrations, indicating that calcite cement is the primary control on porosity and permeability within the Blossom. Sedimentary structures indicative of multidirectional currents and shallow marine fossils suggest that the sands were deposited in nearshore environments. The presence of trace fossils like casts and molds indicate that dissolution and redistribution of biogenic carbonate resulted in calcite cement that controls the porosity and permeability of the Blossom Sand. Gaining a better understanding of the depositional environment and nature of porosity and permeability in sandstone reservoirs like the Blossom Sand can improve success in oil and gas exploration and secondary recovery.

BIOGRAPHY

Hannah Chambers is a graduate of Mississippi State University where she received her B.S. in geology in 2019. Hannah is currently a graduate student at Stephen F. Austin State University where she will graduate with an M.S. in geology in May 2021. Her thesis research focuses on defining the depositional environment and diagenetic features of the Blossom Sand in Panola County, Texas. Hannah is a member of AAPG and SGE and is recognized as a Geologist-In-Training by the Mississippi Board of Registered Professional Geologists.