GEOLOGICAL CONTROLS ON EXPLOITABLE COAL SEAM GAS DISTRIBUTION IN QUEENSLAND

2006 ◽  
Vol 46 (1) ◽  
pp. 343 ◽  
Author(s):  
J. J. Draper ◽  
C.J. Boreham
Keyword(s):  
Coal Seam ◽  
Vitrinite Reflectance ◽  
Gas Production ◽  
Gas Content ◽  
Burial History ◽  
Coal Seam Gas ◽  
Gas Generation ◽  
Delta Plain ◽  
Wide Range ◽  
Gas Fields

Methane is present in all coals, but a number of geological factors influence the potential economic concentration of gas. The key factors are (1) depositional environment, (2) tectonic and structural setting, (3) rank and gas generation, (4) gas content, (5) permeability, and (6) hydrogeology. Commercial coal seam gas production in Queensland has been entirely from the Permian coals of the Bowen Basin, but the Jurassic coals of the Surat and Clarence-Moreton basins are poised to deliver commercial gas volumes.Depositional environments range from fluvial to delta plain to paralic and marginal marine—coals in the Bowen Basin are laterally more continuous than those in the Surat and Clarence-Moreton basins. The tectonic and structural settings are important as they control the coal characteristics both in terms of deposition and burial history. The important coal seam gas seams were deposited in a foreland setting in the Bowen Basin and an intracratonic setting in the Surat and Clarence-Moreton basins. Both of these settings resulted in widespread coal deposition. The complex burial history of the Bowen Basin has resulted in a wide range of coal ranks and properties. Rank in the Bowen Basin coal seam gas fields varies from vitrinite reflectance of 0.55% to >1.1% Rv and from Rv 0.35-0.6% in the Surat and Clarence-Moreton basins in Queensland. High vitrinite coals provide optimal gas generation and cleat formation. The commercial gas fields and the prospective ones contain coals with >60% vitrinite.Gas generation in the Queensland basins is complex with isotopic studies indicating that biogenic gas, thermogenic gas and mixed gases are present. Biogenic processes occur at depths of up to a kilometre. Gas content is important, but lower gas contents can be economic if deliverability is good. Free gas is also present. Drilling and production techniques play an important role in making lower gas content coals viable. Since the Bowen and Surat basins are in a compressive regime, permeability becomes a defining parameter. Areas where the compression is offset by tensional forces provide the best chances for commercial coal seam gas production. Tensional setting such as anticline or structural hinges are important plays. Hydrodynamics control the production rate though water quality varies between the fields.

THE WALLOON COAL MEASURES—THE NEXT COAL SEAM GASTARGET?

2000 ◽  
Vol 40 (1) ◽  
pp. 86
Author(s):  
S.G. Scott ◽  
P. Crosdale
Keyword(s):  
Coal Seam ◽  
Vitrinite Reflectance ◽  
Petroleum Exploration ◽  
Gas Content ◽  
Coal Seam Gas ◽  
Gas Industry ◽  
Permian Coal ◽  
Petroleum Wells ◽  
The Individual ◽  
Coal Measures

The Queensland coal seam gas industry has grown over the last 12 years. During this time the vast majority of exploration wells have targeted the Late Permian coal measures in the Bowen and Galilee Basins. These formations have been the major target because they contain coals with a vitrinite reflectance ranging above 0.7%. This range has always been seen as the main period for methane generation.As well as containing vast quantities of Permian coal, Queensland also has vast quantities of Middle Jurassic coals within its Mesozoic Basins. These coals have received little-to-no exploration for their coal seam gas potential as they have always been interpreted as being immature for gas generation.Over 550 petroleum exploration wells drilled in the Mesozoic Surat Basin of eastern Queensland were reviewed to determine the coal volume of the intersected Walloon Coal Measures. A significant number have intersected large volumes of sub-bituminous to high volatile bituminous coals, in seams ranging up to 11.7 m in thickness. While the individual seams are not laterally persistent, the coal packages can be traced over hundreds of kilometres of the eastern Surat Basin.While only one well has tested the gas content, gas quality and saturation of the Walloon Coal Measures, numerous water bores have reported gas flows from the zone, and petroleum wells intersecting the formation have recorded high mud gas readings during drilling.The relatively shallow depth of the unit over much of the basin, the thickness of the coal packages, the proximity to major gas trunk pipelines and markets make the Walloon Coal Measures an ideal target for the next generation of coal seam gas explorers.

Impact of in-seam drilling performance on coal seam gas production and remaining gas distribution

2019 ◽  
Vol 59 (1) ◽  
pp. 328
Author(s):  
Fengde Zhou ◽  
Glen Fernandes ◽  
Joao Luft ◽  
Kai Ma ◽  
Mahmoud Oraby ◽  
...  
Keyword(s):  
Coal Seam ◽  
Gas Production ◽  
Gas Content ◽  
Gas Distribution ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
Gas Saturation ◽  
Drilling Performance ◽  
Permeability Anisotropy ◽  
The Impact

Drilling horizontal wells in low permeability coal seams is a key technology to increase the drainage area of a well, and hence, decrease costs. It’s unavoidable that some parts of the horizontal section will be drilled outside the targeted coal seam due to unforeseen subsurface conditions, such as sub-seismic faulting, seam rolls, basic geosteering tools, drilling practices and limited experiences. Therefore, understanding the impact of horizontal in-seam drilling performance on coal seam gas (CSG) production and remaining gas distribution is an important consideration in drilling and field development plans. This study presents a new workflow to investigate the impact of horizontal in-seam performance on CSG production and gas distribution for coal seams with different porosity, permeability, permeability anisotropy, initial gas content (GC), initial gas saturation and the ratio of in-coal length to in-seam length (RIIL). First, a box model with an area of 2 km × 0.3 km × 6 m was used for conceptual simulations. Reduction indexes of the cumulative gas production at the end of 10 years of simulations were compared. Then, a current Chevron well consisting of a vertical well and two lateral wells, was selected as a case study in which the impact of outside coal drilling on history matching and remaining gas distribution were analysed. Results show that the RIIL plays an increasing role for cases with decreasing permeability or initial gas saturation, while it plays a very similar role for cases with varied porosity, permeability anisotropy and GC. The size and location of outside coal drilling will affect the CSG production and remaining gas distribution.

Burial History Reconstruction of the Appalachian Basin in Kentucky, West Virginia, Pennsylvania, and New York, Using 1D Petroleum System Models

2019 ◽  
Vol 56 (4) ◽  
pp. 365-396
Author(s):  
Debra Higley ◽  
Catherine Enomoto
Keyword(s):  
New York ◽  
Vitrinite Reflectance ◽  
Structural Complexity ◽  
Appalachian Basin ◽  
Source Rocks ◽  
Burial History ◽  
Gas Generation ◽  
Deep Basin ◽  
Utica Shale ◽  
Wet Gas

Nine 1D burial history models were built across the Appalachian basin to reconstruct the burial, erosional, and thermal maturation histories of contained petroleum source rocks. Models were calibrated to measured downhole temperatures, and to vitrinite reflectance (% Ro) data for Devonian through Pennsylvanian source rocks. The highest levels of thermal maturity in petroleum source rocks are within and proximal to the Rome trough in the deep basin, which are also within the confluence of increased structural complexity and associated faulting, overpressured Devonian shales, and thick intervals of salt in the underlying Silurian Salina Group. Models incorporate minor erosion from 260 to 140 million years ago (Ma) that allows for extended burial and heating of underlying strata. Two modeled times of increased erosion, from 140 to 90 Ma and 23 to 5.3 Ma, are followed by lesser erosion from 5.3 Ma to Present. Absent strata are mainly Permian shales and sandstone; thickness of these removed layers increased from about 6200 ft (1890 m) west of the Rome trough to as much as 9650 ft (2940 m) within the trough. The onset of oil generation based on 0.6% Ro ranges from 387 to 306 Ma for the Utica Shale, and 359 to 282 Ma for Middle Devonian to basal Mississippian shales. The ~1.2% Ro onset of wet gas generation ranges from 360 to 281 Ma in the Utica Shale, and 298 to 150 Ma for Devonian to lowermost Mississippian shales.

scholarly journals Isotopic signatures of major methane sources in the coal seam gas fields and adjacent agricultural districts, Queensland, Australia

2021 ◽  
Vol 21 (13) ◽  
pp. 10527-10555
Author(s):  
Xinyi Lu ◽  
Stephen J. Harris ◽  
Rebecca E. Fisher ◽  
James L. France ◽  
Euan G. Nisbet ◽  
...  
Keyword(s):  
Coal Seam ◽  
Treatment Plant ◽  
Source Attribution ◽  
Multiple Sources ◽  
Coal Seam Gas ◽  
Isotopic Signatures ◽  
Keeling Plot ◽  
Stable Isotopic ◽  
Close Proximity ◽  
Gas Fields

Abstract. In regions where there are multiple sources of methane (CH4) in close proximity, it can be difficult to apportion the CH4 measured in the atmosphere to the appropriate sources. In the Surat Basin, Queensland, Australia, coal seam gas (CSG) developments are surrounded by cattle feedlots, grazing cattle, piggeries, coal mines, urban centres and natural sources of CH4. The characterization of carbon (δ13C) and hydrogen (δD) stable isotopic composition of CH4 can help distinguish between specific emitters of CH4. However, in Australia there is a paucity of data on the various isotopic signatures of the different source types. This research examines whether dual isotopic signatures of CH4 can be used to distinguish between sources of CH4 in the Surat Basin. We also highlight the benefits of sampling at nighttime. During two campaigns in 2018 and 2019, a mobile CH4 monitoring system was used to detect CH4 plumes. Sixteen plumes immediately downwind from known CH4 sources (or individual facilities) were sampled and analysed for their CH4 mole fraction and δ13CCH4 and δDCH4 signatures. The isotopic signatures of the CH4 sources were determined using the Keeling plot method. These new source signatures were then compared to values documented in reports and peer-reviewed journal articles. In the Surat Basin, CSG sources have δ13CCH4 signatures between −55.6 ‰ and −50.9 ‰ and δDCH4 signatures between −207.1 ‰ and −193.8 ‰. Emissions from an open-cut coal mine have δ13CCH4 and δDCH4 signatures of -60.0±0.6 ‰ and -209.7±1.8 ‰ respectively. Emissions from two ground seeps (abandoned coal exploration wells) have δ13CCH4 signatures of -59.9±0.3 ‰ and -60.5±0.2 ‰ and δDCH4 signatures of -185.0±3.1 ‰ and -190.2±1.4 ‰. A river seep had a δ13CCH4 signature of -61.2±1.4 ‰ and a δDCH4 signature of -225.1±2.9 ‰. Three dominant agricultural sources were analysed. The δ13CCH4 and δDCH4 signatures of a cattle feedlot are -62.9±1.3 ‰ and -310.5±4.6 ‰ respectively, grazing (pasture) cattle have δ13CCH4 and δDCH4 signatures of -59.7±1.0 ‰ and -290.5±3.1 ‰ respectively, and a piggery sampled had δ13CCH4 and δDCH4 signatures of -47.6±0.2 ‰ and -300.1±2.6 ‰ respectively, which reflects emissions from animal waste. An export abattoir (meat works and processing) had δ13CCH4 and δDCH4 signatures of -44.5±0.2 ‰ and -314.6±1.8 ‰ respectively. A plume from a wastewater treatment plant had δ13CCH4 and δDCH4 signatures of -47.6±0.2 ‰ and -177.3±2.3 ‰ respectively. In the Surat Basin, source attribution is possible when both δ13CCH4 and δDCH4 are measured for the key categories of CSG, cattle, waste from feedlots and piggeries, and water treatment plants. Under most field situations using δ13CCH4 alone will not enable clear source attribution. It is common in the Surat Basin for CSG and feedlot facilities to be co-located. Measurement of both δ13CCH4 and δDCH4 will assist in source apportionment where the plumes from two such sources are mixed.

Overview of geologic evolution and hydrocarbon generation of the Pannonian Basin

2018 ◽  
Vol 6 (1) ◽  
pp. SB111-SB122 ◽  
Author(s):  
Ferenc Horváth ◽  
Ivan Dulić ◽  
Alan Vranković ◽  
Balázs Koroknai ◽  
Tamás Tóth ◽  
...  
Keyword(s):  
Late Miocene ◽  
Pannonian Basin ◽  
Hydrocarbon Generation ◽  
Burial History ◽  
Gas Generation ◽  
Vertical Movements ◽  
Delta Plain ◽  
Marine Strata ◽  
Shelf Slope ◽  
Oil Generation

The Pannonian Basin is an intraorogenic extensional region floored by a complex system of Alpine orogenic terranes and oceanic suture zones. Its formation dates back to the beginning of the Miocene, and initial fluvial-lacustrine deposits pass into shallow to open marine strata, including a large amount of calc-alkaline volcanic materials erupted during the culmination of the synrift phase. The onset of the postrift phase occurred during the Late Miocene, when the basin became isolated and a large Pannonian lake developed. Early lacustrine marls are overlain by turbiditic sandstones and silts related to a progradational shelf slope and a delta plain sequence passing upward into alluvial plain deposits and eolian sands. A remarkable nonconformity at the top of lacustrine strata associated with a significant (4–7 my) time gap at large parts of the basin documents a neotectonic phase of activity, manifested by regional strike-slip faulting and kilometer-scale differential vertical movements, with erosion and redeposition. Subsidence and burial history modeling indicate that Middle and Late Miocene, fairly organic-rich marine and lacustrine (respectively) shales entered into the oil-generation window at about the beginning of the Pliocene in depocenters deeper than 2.5–3 km, and even reached the wet to dry gas-generation zone at depths exceeding 4–4.5 km. Migration out of these kitchens has been going on since the latest Miocene toward basement highs, where anticlines and flower structures offered adequate trapping conditions for hydrocarbons. We argue that compaction of thick sedimentary piles, in addition to neotectonic structures, has also been important in trap formation within the Pannonian Basin.

Quantitative Evaluation of Coal Seam Gas Content Estimate Accuracy

1995 ◽  
Author(s):  
Matthew J. Mavor ◽  
Timothy J. Pratt ◽  
Charles R. Nelson
Keyword(s):  
Coal Seam ◽  
Quantitative Evaluation ◽  
Gas Content ◽  
Coal Seam Gas

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.

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