Vertical gas migration associated with coal seam gas production

2016 ◽  
Vol 56 (2) ◽  
pp. 602
Author(s):  
Ludovic Ricard ◽  
Julian Strand
Keyword(s):  
Coal Seam ◽  
Risk Evaluation ◽  
Critical Role ◽  
Gas Production ◽  
Mitigation Strategies ◽  
Gas Migration ◽  
Coal Seam Gas ◽  
Gas Reservoirs ◽  
Gas Leakage ◽  
Migration Pathways

Gas migration outside coal seam gas reservoirs has been identified as a risk associated with CSG production. While such an event has not been reported or scientifically associated with CSG production, understanding the physical mechanism of the vertical migration in the overburden involved should gas leakage occur would improve mitigation strategies and risk evaluation. In this extended abstract, a series of key modelling scenarios of gas migration above the reservoir are developed. Interpretation of the scenarios highlights that: the seal/leakage nature of the overburden strongly impacts gas migration and volume of gas leaked; when leakage does occur, the leaked volume represents a very small portion of the original gas in place and volume of gas produced; the connectivity of the overburden plays a critical role on the gas migration pathways and volume of gas leaked; and, residual gas saturation, and relative permeability hysteresis provide means to trap the mobile gas, significantly reducing the volume of gas leaked reaching shallower formations.

The Influence of Formation Dip Angle on Buoyancy-Induced Gas Migration During Coal Seam Gas Production

2021 ◽  
Author(s):  
Mohammad Sedaghat ◽  
Des Owen ◽  
Philip Hayes ◽  
James Underschultz ◽  
Suzanne Hurter ◽  
...  
Keyword(s):  
Coal Seam ◽  
Gas Production ◽  
Gas Migration ◽  
Coal Seam Gas ◽  
Dip Angle ◽  
Formation Dip Angle

Prediction and management of solids production in typical Surat Basin coal seam gas reservoirs, eastern Australia

2015 ◽  
Vol 55 (2) ◽  
pp. 444
Author(s):  
Abbas Khaksar ◽  
Morteza Jami ◽  
Ahmadreza Younessi
Keyword(s):  
Coal Seam ◽  
Water Saturation ◽  
Gas Production ◽  
Control Measures ◽  
Coal Seam Gas ◽  
Gas Reservoirs ◽  
Short Life Span ◽  
Sand Control ◽  
Eastern Australia ◽  
Different Characteristics

The exploiting of coal seam gas (CSG) reservoirs worldwide has developed rapidly. These reservoirs are located in different geological settings and have different characteristics. In eastern Australia for instance, Surat Basin CSG reservoirs are typically thin and interbedded with thick layers of sandstone, siltstones and shales, and occur at shallow depths, adjacent to fresh-water aquifers. For commercial gas production from wet- and low- permeability thin CSG reservoirs, both the hydrostatic pressure and the water saturation have to be reduced through a de-watering and pressure depletion process. These mechanisms increase the risk of rock failure and solids production before or from the onset of gas production in many CSG wells. In thinly bedded CSG reservoirs, solids production from coals may not be a concern, but sanding from interbed rocks—some with abundant water sensitive clay minerals—may be a significant source of solids production. Given the relatively low drilling and completion costs and short life span of the CSG wells, many of the conventional sand control measures such as screens or gravel packs may be of limited use or not applicable. In this extended abstract, examples of solids production issues and the potential sources of solids in typical Surat Basin CSG wells are shown, and options for solids control are discussed.

scholarly journals A Generic Method for Predicting Environmental Concentrations of Hydraulic Fracturing Chemicals in Soil and Shallow Groundwater

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 941 ◽  
Author(s):  
Dirk Mallants ◽  
Elise Bekele ◽  
Wolfgang Schmid ◽  
Konrad Miotlinski ◽  
Andrew Taylor ◽  
...  
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Shallow Groundwater ◽  
Solute Concentration ◽  
Coal Seam Gas ◽  
Transport Modelling ◽  
Environmental Concentrations ◽  
Modelling Framework ◽  
Recharge Rates ◽  
Migration Pathways

Source-pathway-receptor analyses involving solute migration pathways through soil and shallow groundwater are typically undertaken to assess how people and the environment could come into contact with chemicals associated with coal seam gas operations. For the potential short-term and long-term release of coal seam gas fluids from storage ponds, solute concentration and dilution factors have been calculated using a water flow and solute transport modelling framework for an unsaturated zone-shallow groundwater system. Uncertainty about dilution factors was quantified for a range of system parameters: (i) leakage rates from storage ponds combined with recharge rates, (ii) a broad combination of soil and groundwater properties, and (iii) a series of increasing travel distances through soil and groundwater. Calculated dilution factors in the soil increased from sand to loam soil and increased with an increasing recharge rate, while dilution decreased for a decreasing leak rate and leak duration. In groundwater, dilution factors increase with increasing aquifer hydraulic conductivity and riverbed conductance. For a hypothetical leak duration of three years, the combined soil and groundwater dilution factors are larger than 6980 for more than 99.97% of bores that are likely to be farther than 100 m from the source. Dilution factors were more sensitive to uncertainty in leak rates than recharge rates. Based on this dilution factor, a comparison of groundwater predicted environmental concentrations and predicted no-effect concentrations for a subset of hydraulic fracturing chemicals used in Australia revealed that for all but two of the evaluated chemicals the estimated groundwater concentration (for a hypothetical water bore at 100 m from the solute source) is smaller than the no-effect concentration for the protection of aquatic ecosystems.

Beneficial use of associated water in the Queensland coal seam gas industry

2010 ◽  
Vol 50 (2) ◽  
pp. 686
Author(s):  
Cristian Purtill
Keyword(s):  
Water Management ◽  
Coal Seam ◽  
Single Mode ◽  
Gas Production ◽  
Management Policy ◽  
Coal Seam Gas ◽  
Gas Industry ◽  
Beneficial Use ◽  
Challenges And Opportunities ◽  
Water Management Strategy

The Queensland Government has developed an associated water management policy that, among other things, strives to maximise the beneficial use of associated water derived from Queensland’s burgeoning coal seam gas industry. The Department of Infrastructure and Planning reports that domestic gas production alone (i.e. without an export LNG market) will produce on average 25 GL per annum in the next 25 years. Most of this water has sufficiently high total dissolved solids and other water quality issues to require some form of treatment prior to use. Clearly, the relatively large volumes of water present both challenges and opportunities to the communities in which the CSG industry is developing. In line with the philosophy of beneficial use of associated water, Santos has developed a portfolio of options within its associated water management strategy and plans for its Arcadia Valley, Fairview and Roma tenements. The strategy seeks to: provide enduring value for the community; maximise benefits while minimising the environmental footprint; provide a range of alternatives to avoid single-mode failure; use scalable options in response to uncertainty; deploy demonstrated technologies; and, meet and exceed all regulatory requirements. This paper will set some context around the broader CSG industry’s associated water challenges, and identify what parameters must be considered in arriving at beneficial uses for the water. The paper then explores some of Santos’ approaches to associated water management.

Determining the impacts of coal seam gas extraction on water-dependent assets

2016 ◽  
Vol 56 (2) ◽  
pp. 545
Author(s):  
David Post ◽  
Peter Baker ◽  
Damian Barrett
Keyword(s):  
Coal Seam ◽  
Indigenous Peoples ◽  
Rural Areas ◽  
Scientific Information ◽  
Gas Production ◽  
Specific Reference ◽  
Catchment Management ◽  
State Governments ◽  
Coal Seam Gas ◽  
Coal Resource

Many Australians, particularly in rural areas, are seeking clear scientific information about the potential impacts of coal seam gas production on groundwater and surface water across the country. In response to the resultant community concern, the Australian Government commissioned an ambitious multi-disciplinary program of bioregional assessments to improve understanding of the potential impacts of coal seam gas (and large coal mining) activities on water-dependent assets across six bioregions in eastern and central Australia. Delivered through a collaboration between the Department of the Environment, the Bureau of Meteorology, CSIRO, and Geoscience Australia—and including close engagement with natural resource management and catchment management organisations, coal resource companies, Indigenous peoples and state governments—the results will allow coal resource companies, governments, and the community to focus on the areas where impacts may occur so that these can be minimised. Key findings of the program will be presented with specific reference to the potential impacts on water-dependent assets due to CSG development by Metgasco and AGL in the Clarence-Moreton and Gloucester regions, respectively.

scholarly journals Mathematical modelling of gas production and compositional shift of a CSG (coal seam gas) field: Local model development

Energy ◽  
2015 ◽  
Vol 88 ◽  
pp. 621-635 ◽  
Author(s):  
Steven Psaltis ◽  
Troy Farrell ◽  
Kevin Burrage ◽  
Pamela Burrage ◽  
Peter McCabe ◽  
...  
Keyword(s):  
Coal Seam ◽  
Mathematical Modelling ◽  
Model Development ◽  
Gas Production ◽  
Local Model ◽  
Coal Seam Gas ◽  
Gas Field
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