GSA Connects 2021 in Portland, Oregon

Paper No. 137-5
Presentation Time: 9:10 AM


LOREE, Peter and QUAN, Tracy M., Boone Pickens School of Geology, Oklahoma State University, 105 Noble Research Center, Stillwater, OK 74078

Water can make up a significant portion of the output generated by petroleum wells, in some cases as high as 7 times the petroleum output per well. This produced water (PW) typically is more saline than ocean water and has a highly heterogeneous composition of organic and inorganic compounds. Additionally, this composition can vary on a per-well basis. This can limit characterization if some sort of processing is not performed prior to analysis. For our project, we utilize nuclear magnetic resonance (NMR) techniques to acquire interpretable data from whole-water analysis of PW. NMR analysis is a well-documented technique capable of non-destructive description of various compounds. We used a water-suppression experiment designated PE-ES-WATERGATE to acquire a qualitative assessment of organic compound classes present in 18 samples collected from the Black Warrior Basin in Alabama. Results were then compared with previous studies to gain insight into possible trends related to the presence or absence of organic compounds. Results indicate approximately one third of samples show significant detectable organic compound signals, the majority of which are located between 0.0-4.0ppm. These are currently interpreted as likely belonging to alkane, allylic alkenes and other aliphatic compound classes. Smaller peaks observed between 7.5-8.5ppm are interpreted to be phenols, based on previous work characterizing the Black Warrior Basin. An unresolved complex mixture (UCM) is also present, most frequently between 1.0-2.5ppm. Previous reporting on the basin indicated significant freshwater input into the local groundwater from the east and southeast, which resulted in reduced salinity and total dissolved solids (TDS) of produced water in those areas. Our results indicate that organic compounds appear to be similarly affected, with a general decrease in discrete signals relative to the UCM.