Unconventional hydrocarbons in shales: source rock or waste zones?

2015 ◽  
Vol 55 (2) ◽  
pp. 474
Author(s):  
Nachiketa Mishra ◽  
John Kaldi ◽  
Ulrike Schacht
Keyword(s):  
Organic Compounds ◽  
Hydrocarbon Generation ◽  
Bakken Formation ◽  
Unconventional Resources ◽  
Hydrocarbon Content ◽  
Basin Scale ◽  
Unconventional Hydrocarbons ◽  
Mercury Injection Capillary Pressure ◽  
Continuous Source ◽  
Cooper Basin

This extended abstract summarises the objectives of a research project that will provide insight into hydrocarbon generation and accumulation in continuous-source reservoirs and how to best exploit such unconventional resources in Australia, specifically in the Cooper Basin. It compares and contrasts a productive shale from the US—the Bakken Formation—with shales from the Cooper Basin. Unconventional resources, such as the Devonian-Mississippian Bakken Formation, have been assumed to be continuous source-reservoirs where the oil is generated from organic-rich shales with minimal migration. It is possible, however, that the shale intervals are a waste zone (a leaked seal). These waste zones form when the buoyancy pressure of the hydrocarbon exceeds the capillary forces in the seal, resulting in tertiary migration. Oil saturation values strongly correlate with the hydrocarbon content parameter (S1/TOC) from Rock-Eval. Values of 120 mgHC/gC are typically indicative of non-indigenous or migrated hydrocarbons (reservoirs or leaked seals). Mercury injection capillary pressure (MICP) analysis of core samples can also diagnose whether a shale is a source or a seal. Organic shales with high capillary entry pressures generally have low hydrocarbon content, in line with in-situ generation; shales with low entry pressures have comparatively higher hydrocarbon content and indicate migration from an underlying accumulation. Once these waste zones are identified on a basin-scale, specific samples from the Bakken Formation will be analysed using micro-scale sealed vessel pyrolysis, combined with monitoring of the biomarkers and other organic compounds using mass spectrometry. As the composition of organic compounds is altered during migration, this will confirm whether they are generated locally or migrated.

scholarly journals Contributions to local and regional-scale formaldehyde concentrations

2018 ◽  
Author(s):  
Lucas Bastien ◽  
Nancy Brown ◽  
Robert Harley
Keyword(s):  
Organic Compounds ◽  
San Francisco ◽  
Transport Model ◽  
Regional Scale ◽  
Air Pollutant ◽  
Chemical Transport Model ◽  
Adjoint Sensitivity ◽  
Voc Emissions ◽  
Mixing Ratios ◽  
Basin Scale

Abstract. Reducing ambient formaldehyde concentrations is a complex task because formaldehyde is both a primary and a secondary air pollutant, with significant anthropogenic and biogenic sources of volatile organic compounds (VOC) precursor emissions. This work uses adjoint sensitivity analysis in a chemical transport model to identify emission sources and chemical reactions that influence formaldehyde mixing ratios in the San Francisco Bay Area, and within three urbanized sub-areas. For each of these receptors, the use of the adjoint technique allows for efficient calculation of the sensitivity of formaldehyde to emissions of NOx, formaldehyde, and VOC precursors occurring at any location and time. Formaldehyde mixing ratios are found to be generally higher in summer than in winter. The opposite seasonal trend is observed for the sensitivities of these mixing ratios to formaldehyde emissions. In other words, even though formaldehyde is higher in summer, reducing formaldehyde emissions has a greater impact in winter. In winter, 85–90 % of the sensitivity to emissions is attributed to direct formaldehyde emissions. In summer, this contribution is smaller and more variable, ranging from 26 to 72 % among the receptor areas investigated in this study. Higher relative contributions of secondary formation versus direct emissions are associated with receptors located farther away from heavily urbanized and emission-rich areas. In particular, the relative contribution of biogenic VOC emissions (15–41 % in summer) is largest for these receptors. Ethene and other alkenes are the most influential anthropogenic precursors to secondary formaldehyde. Isoprene is the most influential biogenic precursor. Sensitivities of formaldehyde to NOx emissions are generally negative, but small in magnitude compared to sensitivities to VOC emissions. The magnitude of anthropogenic emissions of organic compounds other than formaldehyde is found to correlate reasonably well with their influence on population-weighted formaldehyde mixing ratios at the air basin scale. This correlation does not hold for ambient formaldehyde in smaller urbanized sub-areas. The magnitude of biogenic emissions does not correlate with their influence in either case.

Unconventional gas prospectivity of the Cooper Basin

2015 ◽  
Vol 55 (2) ◽  
pp. 428 ◽  
Author(s):  
Lisa Hall ◽  
Tony Hill ◽  
Liuqi Wang ◽  
Dianne Edwards ◽  
Tehani Kuske ◽  
...  
Keyword(s):  
Source Rocks ◽  
System Modelling ◽  
Hydrocarbon Generation ◽  
Tight Gas ◽  
Unconventional Gas ◽  
Upper Carboniferous ◽  
Gas Market ◽  
Intracratonic Basin ◽  
Exploration Activity ◽  
Cooper Basin

The Cooper Basin is an Upper Carboniferous–Middle Triassic intracratonic basin in northeast SA and southwest Queensland. The basin is Australia's premier onshore hydrocarbon-producing province and is nationally significant due to its provision of domestic gas for the east coast gas market. Exploration activity in the region has recently expanded with numerous explorers pursuing newly identified unconventional hydrocarbon plays. While conventional gas and oil prospects can usually be identified by 3D seismic, the definition and extent of the undiscovered unconventional gas resources in the basin remain poorly understood. This extended abstract reviews the hydrocarbon prospectivity of the Cooper Basin with a focus on unconventional gas resources. Regional basin architecture, characterised through source rock distribution and quality, demonstrates the abundance of viable source rocks across the basin. Petroleum system modelling, incorporating new compositional kinetics, source quality and total organic carbon (TOC) map, highlight the variability in burial, thermal and hydrocarbon generation histories between depocentres. The study documents the extent of a number of unconventional gas play types, including the extensive basin-centred and tight gas accumulations in the Gidgealpa Group, deep-dry coal gas associated with the Patchawarra and Toolachee formations, as well as the less extensive shale gas plays in the Murteree and Roseneath shales.

From play to production: the Cooper unconventional story—20 years in the making

2015 ◽  
Vol 55 (2) ◽  
pp. 407 ◽  
Author(s):  
Carl Greenstreet
Keyword(s):  
East Coast ◽  
Market Access ◽  
Horizontal Wells ◽  
Gas Flows ◽  
Resource Potential ◽  
Unconventional Resources ◽  
Gas Shales ◽  
Reservoir Conditions ◽  
Structural Closure ◽  
Cooper Basin

The Cooper Basin is Australia’s leading onshore producing hydrocarbon province, having produced more than 6 Tcf of natural gas since 1969. The basin is undergoing renewal 45 years later, driven by the emerging growth of east coast LNG export-driven demand. Following North America’s shale gas revolution, the Cooper Basin’s unconventional potential is now widely appreciated and it is believed to hold more than 100 Tcf of recoverable gas. This resource potential is held in four stacked target unconventional lithotypes, each having demonstrated gas flows: tight sands—heterogeneous stacked fluvial sands; deep coal—porous dry coals, oversaturated with gas; shales—thick, regionally extensive lacustrine shales; and, hybrid shales—mixed lithotype containing interbedded tight sandstones, shales and coals. Industry activity initially focused on the Nappamerri Trough, where more than 25 contemporary exploration wells have been drilled, proving up an extensive basin-centred gas play with >1,000 m of continuous overpressured gas saturated section outside of structural closure. Santos has had a team focused on unconventional resources for nearly 20 years and successful results have been quickly tied into the producing infrastructure. This has been demonstrated with the Moomba–191 REM shale success, Moomba–194 and the recent Moomba–193H connection, one of the basin’s first fracture-stimulated horizontal wells. Prospective geology, existing infrastructure and market access makes the Cooper Basin well positioned for unconventional success. Each resource play is unique and commercial success requires considered adaptation of established technologies and workflows, based on a understanding of local geological and reservoir conditions. Commercialisation activity now seeks to define play fairways, characterise and prioritise reservoir targets and determine appropriate drilling and completion approaches.

Constraining the distribution and relationship between overpressure, natural fracture density and temperature in the Cooper Basin, Australia

2016 ◽  
Vol 56 (1) ◽  
pp. 11 ◽  
Author(s):  
David Kulikowski ◽  
Dennis Cooke ◽  
Khalid Amrouch
Keyword(s):  
Uranium Content ◽  
Natural Fracture ◽  
Hydrocarbon Generation ◽  
Fracture Density ◽  
Fracture Detection ◽  
Field Scale ◽  
Seismic Attribute ◽  
Fracture Development ◽  
Generation Mechanisms ◽  
Cooper Basin

To effectively and safely extract hydrocarbon from low permeability and overpressured reservoirs in the Cooper Basin, a thorough understanding of the regional and field scale distribution of overpressure, temperature and fracture density is essential. Previous research omitted the effect of fluid expansion and hydrocarbon generation mechanisms for overpressure generation in the basin, albeit reservoir temperatures have sharply increased in the past five million years. The authors collate pressure (>8,000 samples) and temperature (>6,000 samples) data from 1,095 wells across the SA portion of the Cooper Basin and incorporate natural fracture densities from 28 interpreted borehole image logs to investigate the spatial variation, and potential relationship, between pressure, temperature and natural fracture density. Results show significantly lower geothermal gradients within the Patchawarra Trough, likely attributed to a lack of shallow volcanics, blanketing coals or low uranium content. Shallow volcanics are common in high-temperature areas such as the Moomba/Big Lake and Gidgealpa fields and deeper portions of the Nappamerri Trough, with overpressured wells (>0.45 psi/ft) appearing to cluster in these areas, particularly south of the Gidgealpa-Merrimelia-Innamincka Ridge. Fracture density shows no obvious relationship to pressure, inferring a dominant structural origin for natural fracture development. Although the authors cannot exclusively attribute fluid expansion and hydrocarbon expansion mechanisms to overpressure, they likely have a profound effect. Future work should investigate the feasibility of integrating pressure, vertical stress and sonic velocity to constrain the overpressure generation mechanism within the basin while incorporating field scale seismic attribute analysis for natural fracture detection and overpressure analysis.

DETERMINATION OF THE HYDROCARBON PROSPECTIVITY OF SEDIMENTS BY HYDROGENATION

1984 ◽  
Vol 24 (1) ◽  
pp. 222 ◽  
Author(s):  
E. J. Evans ◽  
B. D. Batts
Keyword(s):  
Liquid Hydrocarbon ◽  
Land Plant ◽  
Source Rocks ◽  
Hydrocarbon Potential ◽  
Hydrocarbon Generation ◽  
Hydrocarbon Content ◽  
Hydrocarbon Maturation ◽  
Significant Difference ◽  
Recent Developments ◽  
Exploratory Wells

Recent developments in hydrogenation procedures allow the liquid hydrocarbon potential and the total liquid hydrocarbon content of source rocks to be determined directly. In essence, mild controlled hydrogenation. without the cleavage of C-C bonds, converts the recognized hydrocarbon precursors in immature source rocks, i.e. the largely aliphatic acids, alcohols, esters, etc., into the parent alkanes. These alkanes, which have a distinctive composition, are easily collected and determined in toto by routine analytical processes. Thus hydrocarbon potentials are immediately revealed.Since the bulk of Australian crudes are of land plant (humic) origin, initial investigations have been largely concentrated on vitrinites and inertinites separated from Australian coals. These studies have shown that:the formation, on hydrogenation, of alkanes with a distinctive composition is an excellent guide to sediment maturity and to hydrocarbon potential; hydrocarbon generation, although not hydrocarbon maturation, is complete when the reflectance of vitrinite in contributing sediments approximates 0.65 per cent; and no significant difference exists between the hydrocarbon potentials and the hydrocarbon content of associated inertinites and vitrinites when the reflectance of the latter is in the range 0.3 to 1.2 per cent. These findings provide a guide to basin potentials and an explanation for the unexpected prospectivity of inertinite-rich Australian sediments.Results of applying this procedure to sediment samples from exploratory wells in the Gippsland and Cooper Basins have generally followed trends seen with coal samples and confirmed the value of the method in determining hydrocarbon potentials.

scholarly journals Organic compounds in produced waters from the Bakken Formation and Three Forks Formation in the Williston Basin, North Dakota

Heliyon ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. e03590
Author(s):  
Matthew S. Varonka ◽  
Tanya J. Gallegos ◽  
Anne L. Bates ◽  
Colin Doolan ◽  
William H. Orem
Keyword(s):  
North Dakota ◽  
Organic Compounds ◽  
Williston Basin ◽  
Bakken Formation ◽  
Three Forks Formation ◽  
Three Forks ◽  
Produced Waters

AN EXPERIMENT IN SOIL GEOCHEMICAL PROSPECTING FOR PETROLEUM, DELLA GAS FIELD, COOPER BASIN

1975 ◽  
Vol 15 (1) ◽  
pp. 103
Author(s):  
S. B. Devine ◽  
H. W. Sears
Keyword(s):  
Gamma Ray ◽  
Analytical Techniques ◽  
Statistical Correlation ◽  
Gas Field ◽  
Mean Values ◽  
Gamma Ray Spectrometer ◽  
Hydrocarbon Content ◽  
Soluble Material ◽  
Cooper Basin ◽  
Propane Butane

The aim of the experiment was to test the method of prospecting for petroleum by soil geochemical analysis of hydrocarbons and, in particular, its possible application in the Cooper Basin. Some 379 samples were taken in traverses across the Della Gas Field and a nearby, undrilled anticlinal structure. The samples were taken from a depth of 5 m at a spacing of 5 per mile (approximately 1 every 300 m). Hydrocarbons were extracted with 2N HCI and analysed by gas chromatography. Some modifications to the published analytical techniques had to be made to overcome the prbblem of traces of organic compounds present in local waters and reagents.Arithmetic mean values analysed for the Della Gas Field were: acid soluble material, 8.62 per cent; ethane, 1.33 ppm; propane, 0.77 ppm; butane, 0.62 ppm; pentane, 0.84 ppm. In plots of, firstly, the sum of ethane, propane, butane and pentane and secondly that sum normalized to the amount of acid soluble material, anomalous areas containing only a few sample points occur above and near the Della Field, and the undrilled structure.There is only low statistical correlation between the amount of acid soluble material and the hydrocarbon content of the soils. The hydrocarbon content of the soils may possibly be associated with diagenetic gypsum and calcite and possibly smectite (?mixed layer clay) but the evidence is inconclusive. The soil hydrocarbon content shows some tendency to correlate with the finer grain sizes. The anomalies appear to bear no relation to the vegetation. A radiometric survey with a gamma ray spectrometer showed little variation of values and no relation to the geochemistry nor the outline of the Della Gas Field.The experiment has shown that significant variations in hydrocarbon content of the soils can be analysed in the Cooper Basin and apparent anomalous zones can be outlined. The anomalous zones may be related to the Della Gas Field.

SOURCE, MATURITY AND GAS COMPOSITION RELATIONSHIPS IN THE SOUTHERN COOPER BASIN

1980 ◽  
Vol 20 (1) ◽  
pp. 191
Author(s):  
D.A. Schwebel ◽  
S.B. Devine ◽  
M. Riley
Keyword(s):  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
Geothermal Gradient ◽  
Temperature Gradients ◽  
Land Plants ◽  
Hydrocarbon Generation ◽  
Gas Composition ◽  
Wet Gas ◽  
Structural Zones ◽  
Cooper Basin

In the Permian sedimentary sequence of the Cooper Basin, land plants contributed the bulk of the organic matter to the sediments. Inertinite, vitrinite and exinite are common kerogen types present in the organic-rich shales. Coal thickness varies areally.The geothermal gradient, though varying (from area to area), is everywhere higher than normal for sedimentary basins. The whole of the Permian sequence is mature for hydrocarbon generation. The highest temperature gradients of up to 3.19°F/100’ are measured in the Nappamerrie Trough and are associated with areas of granitic basement. Vitrinite reflectance profiles confirm that the sediments are thermally mature.Trends of gas composition indicate three distinct regions with gases trapped in:the Patchawarra Trough tend to be high in CO2 and wet gas;the Nappamerri Trough tend to be high in CO2 and low in wet gas; andthe Tennapera Trough tend to be low in CO2 and moderately high in wet gas.These differences in gas composition are accounted for by differences in thermal history within structural zones.

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