Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $25,000 Total Non-Federal Funds: $50,000
Principal Investigators: Joseph Suflita, Irene Davidova
Abstract: Oil and gas in Oklahoma are regularly extracted from unconventional reservoirs using a combination of horizontal drilling and hydraulic fracturing techniques. These procedures can generate remarkable volumes of produced water (PW) that routinely get injected into the terrestrial subsurface via disposal wells. The correlation of this practice with increased seismic activity, prompted the OK Corporation Commission to reduce the volume of PW disposed. A study group recommended reuse of fracturing water so that less needed final disposal. Unfortunately, microbial activities that generate acid and sulfides diminish the prospects of PW recycling. The proposed efforts will explore inexpensive mechanisms to control the predominant microbial population responsible for the undesirable properties of PW and make the water more suitable for re-use. This approach also has the prospect of augmenting the use of biocides. These expensive chemicals are routinely used to control microbial activities in PW, but the overall effectiveness of this approach appears limited. Studies performed by us and other research groups demonstrated that PW from Barnett, Marcellus, Utica, Burket/Geneso and Antrim shales are often dominated by a single bacterial Order, the Halanaerobiales. The predominance of Halanaerobiales represents an opportunity to differentially impact the prospects of PW recycling through attempts to control Halanaerobium metabolism, or by finding the physico-chemical conditions that restrict the growth of this bacterium. Thus, the major objective of the proposal will be to find suitable and inexpensive methods to limit the activity and proliferation of problematic Halanaerobiales so that PW can be more readily reused. We will explore the ecological boundaries associated with these organisms relative to the operational and geochemical factors associated with hydraulic fracturing fluids. Specifically, we will determine the salinity conditions that effectively limit Halanaerobiales. While information on the lower salinity tolerance limits for this organisms are known, comparable information on the upper tolerance limits are not. Salts for the manipulation of PW salinity characteristics can be obtained by evaporation, another inexpensive procedure used to reduce PW disposal volume. We will use Halanaerobium strain DL-01 as a model organism in this study. This strain was obtained from a hydraulically fractured site in the Barnett by our laboratory. We intend to cultivate this bacterium under a range of salinities to determine the upper tolerance limits while evaluating both growth and the rates of thiosulfate reduction. We will also interrogate genomic data for strain DL-01 and other Halanaerobiales (once the ongoing sequencing effort headed by K. Wrighton laboratory at Ohio State Univ. is publically available) in search of clues on potential inhibitors that can interrupt crucial metabolic pathways. We will, also, survey the literature and investigate approaches for the induction of prophages responsible for bacterial lysis. Preliminary reports suggest that prophages are inherent in the genomes of Halanaerobium strain DL-01 (personal communication).