Composition and Origin of Surface Casing Fluids in a Major US Oil- and Gas-Producing Region.

Fluids leaked from oil and gas wells often originate from their surface casing─a steel pipe installed beneath the deepest underlying source of potable groundwater that serves as the final barrier around the well system. In this study, we analyze a regulatory dataset of surface casing geochemical samples collected from 2573 wells in northeastern Colorado─the only known publicly available dataset of its kind. Thermogenic gas was present in the surface casings of 96.

Public data from three US states provide new insights into well integrity.

Oil and gas wells with compromised integrity are a concern because they can potentially leak hydrocarbons or other fluids into groundwater and/or the atmosphere. Most states in the United States require some form of integrity testing, but few jurisdictions mandate widespread testing and open reporting on a scale informative for leakage risk assessment. In this study, we searched 33 US state oil and gas regulatory agency databases and identified records useful for evaluating well integrity in Colorado, New Mexico, and Pennsylvania.

Probabilistic Assessment of Above Zone Pressure Predictions at a Geologic Carbon Storage Site.

Carbon dioxide (CO) storage into geological formations is regarded as an important mitigation strategy for anthropogenic CO emissions to the atmosphere. This study first simulates the leakage of CO and brine from a storage reservoir through the caprock. Then, we estimate the resulting pressure changes at the zone overlying the caprock also known as Above Zone Monitoring Interval (AZMI).

Spatial and Temporal Characteristics of Historical Oil and Gas Wells in Pennsylvania: Implications for New Shale Gas Resources.

Recent large-scale development of oil and gas from low-permeability unconventional formations (e.g., shales, tight sands, and coal seams) has raised concern about potential environmental impacts.

Measurement and modeling of CO₂ solubility in natural and synthetic formation brines for CO₂ sequestration.

CO2 solubility data in the natural formation brine, synthetic formation brine, and synthetic NaCl+CaCl2 brine were collected at the pressures from 100 to 200 bar, temperatures from 323 to 423 K. Experimental results demonstrate that the CO2 solubility in the synthetic formation brines can be reliably represented by that in the synthetic NaCl+CaCl2 brines. We extended our previously developed model (PSUCO2) to calculate CO2 solubility in aqueous mixed-salt solution by using the additivity rule of the Setschenow coefficients of the individual ions (Na(+), Ca(2+), Mg(2+), K(+), Cl(-), and SO4(2-)).

Quantifying the benefit of wellbore leakage potential estimates for prioritizing long-term MVA well sampling at a CO2 storage site.

This work uses probabilistic methods to simulate a hypothetical geologic CO2 storage site in a depleted oil and gas field, where the large number of legacy wells would make it cost-prohibitive to sample all wells for all measurements as part of the postinjection site care. Deep well leakage potential scores were assigned to the wells using a random subsample of 100 wells from a detailed study of 826 legacy wells that penetrate the basal Cambrian formation on the U.S.

Leakage detection of Marcellus Shale natural gas at an Upper Devonian gas monitoring well: a 3-d numerical modeling approach.

Potential natural gas leakage into shallow, overlying formations and aquifers from Marcellus Shale gas drilling operations is a public concern. However, before natural gas could reach underground sources of drinking water (USDW), it must pass through several geologic formations. Tracer and pressure monitoring in formations overlying the Marcellus could help detect natural gas leakage at hydraulic fracturing sites before it reaches USDW.

Volumetrics of CO2 storage in deep saline formations.

Concern about the role of greenhouse gases in global climate change has generated interest in sequestering CO(2) from fossil-fuel combustion in deep saline formations. Pore space in these formations is initially filled with brine, and space to accommodate injected CO(2) must be generated by displacing brine, and to a lesser extent by compression of brine and rock. The formation volume required to store a given mass of CO(2) depends on the storage mechanism.

Production, purification, and characterization of a fusion protein of carbonic anhydrase from Neisseria gonorrhoeae and cellulose binding domain from Clostridium thermocellum.

Carbon dioxide capture technologies have the potential to become an important climate change mitigation option through sequestration of gaseous CO2. A new concept for CO2 capture involves use of immobilized carbonic anhydrase (CA) that catalyzes the reversible hydration of CO2 to HCO3(-) and H+. Cost-efficient production of the enzyme and an inexpensive immobilization system are critical for development of economically feasible CA-based CO2 capture processes.

Sequestration of dissolved CO2 in the Oriskany formation.

Experiments were conducted to determine the solubility of CO2 in a natural brine solution of the Oriskany formation under elevated temperature and pressure conditions. These data were collected at temperatures of 22 and 75 degrees C and pressures between 100 and 450 bar. Experimentally determined data were compared with CO2 solubility predictions using a model developed by Duan and Sun (Chem.

Kinetics of chemoheterotrophic microbially mediated reduction of ferric EDTA and the nitrosyl adduct of ferrous EDTA for the treatment and regeneration of spent nitric oxide scrubber liquor.

Biomass from a prototype reactor was used to investigate the kinetics of chemoheterotrophic reduction of solutions of ferric ethylenediaminetetraacetic acid (EDTA) and solutions containing the nitrosyl adduct of ferrous EDTA using ethanol as the primary electron donor and carbon source. A series of batch experiments were conducted using biomass extracted from the scrubber solution treatment and regeneration stage of a prototype iron EDTA-based unit process for the absorption of nitric oxide with subsequent biological treatment. Using a linear-sweep voltammetric method for analysis of the ferric EDTA concentration, iron-reducing bacteria were found to behave according to the Monod kinetic model, at initial concentrations up to 2.