Thermal and hydrocarbon-charge history and the relationship between diagenesis and reservoir connectivity: Venture field, offshore Nova Scotia, eastern Canada1Geological Survey of Canada Contribution 20100418.

2011 ◽  
Vol 48 (9) ◽  
pp. 1293-1306 ◽  
Author(s):  
Atika Karim ◽  
Georgia Pe-Piper ◽  
David J.W. Piper ◽  
Jacob J. Hanley
Keyword(s):  
Nova Scotia ◽  
Fluid Inclusions ◽  
Upper Jurassic ◽  
Gas Reservoirs ◽  
Carbonate Cements ◽  
Migration History ◽  
Carbonate Cementation ◽  
Homogenization Temperatures ◽  
Hydrocarbon Charge ◽  
Reservoir Connectivity

Fluid inclusions in diagenetic cements in Upper Jurassic – Lower Cretaceous sandstones offshore Nova Scotia provide constraints on the fluid migration history in gas reservoirs of the Scotian basin. Diagenetic minerals from six wells in the Venture field were analysed by optical petrography, scanning electron microscopy (SEM), and electron microprobe. A total of 122 primary and secondary fluid inclusions were analysed from different cements. Primary aqueous inclusions in quartz overgrowths have homogenization temperatures (Th) of 111.8 ± 7.1 °C (1σ) and in later carbonate cements 126.5 ± 2.1 °C; inclusions in both cements are highly saline (16–26.1 wt.% NaCl equivalent). Secondary aqueous and hydrocarbon-bearing inclusion trails crosscutting silica cement and detrital quartz have Th of 121.6 ± 13.6 °C and low salinities (8.7 ± 6.0 wt.%). Secondary carbonic inclusions have CO2 melting temperatures (–56.6 ± 0.1 °C) and Th (–9.3 ± 0.8 °C) indicating a high-density carbonic phase. Late carbonate cements in the same sandstone units vary in chemical composition in different wells, and connected reservoirs show similar late carbonate assemblages, suggesting that the late carbonate cementation may be partly controlled by the reservoir fill and spill sequence. Silica and late carbonate cementation involved highly saline fluid flow, likely at about ∼135 Ma. Hydrocarbon migration postdated silica cementation and was associated with secondary fracturing, suggesting that it corresponded to the onset of overpressure.

scholarly journals Tungsten Ores of the Dzhida W-Mo Ore Field (Southwestern Transbaikalia, Russia): Mineral Composition and Physical-Chemical Conditions of Formation

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 725
Author(s):  
Ludmila B. Damdinova ◽  
Bulat B. Damdinov
Keyword(s):  
Mineral Composition ◽  
Fluid Inclusions ◽  
Apical Part ◽  
Hydrothermal Fluids ◽  
True Temperature ◽  
Gangue Mineral ◽  
Mineral Formation ◽  
Physical Chemical ◽  
Homogenization Temperatures ◽  
Chemical Conditions

This article discusses the peculiarities of mineral composition and a fluid inclusions (FIs further in the text) study of the Kholtoson W and Inkur W deposits located within the Dzhida W-Mo ore field (Southwestern Transbaikalia, Russia). The Mo mineralization spatially coincides with the apical part of the Pervomaisky stock (Pervomaisky deposit), and the W mineralization forms numerous quartz veins in the western part of the ore field (Kholtoson vein deposit) and the stockwork in the central part (Inkur stockwork deposit). The ore mineral composition is similar at both deposits. Quartz is the main gangue mineral; there are also present muscovite, K-feldspar, and carbonates. The main ore mineral of both deposits is hubnerite. In addition to hubnerite, at both deposits, more than 20 mineral species were identified; they include sulfides (pyrite, chalcopyrite, galena, sphalerite, bornite, etc.), sulfosalts (tetrahedrite, aikinite, stannite, etc.), oxides (scheelite, cassiterite), and tellurides (hessite). The results of mineralogical and fluid inclusions studies allowed us to conclude that the Inkur W and the Kholtoson W deposits were formed by the same hydrothermal fluids, related to the same ore-forming system. For both deposits, the fluid inclusion homogenization temperatures varied within the range ~195–344 °C. The presence of cogenetic liquid- and vapor-dominated inclusions in the quartz from the ores of the Kholtoson deposit allowed us to estimate the true temperature range of mineral formation as 413–350 °C. Ore deposition occurred under similar physical-chemical conditions, differing only in pressures of mineral formation. The main factors of hubnerite deposition from hydrothermal fluids were decreases in temperature.

Telluride Mineralogy of the Deer Horn Au-Ag-Te-(Bi-Pb-W) Deposit, British Columbia: Implications for the Generation of Tellurides

2021 ◽  
Author(s):  
Jordan A. Roberts ◽  
Lee A. Groat ◽  
Paul G. Spry ◽  
Jan Cempírek
Keyword(s):  
British Columbia ◽  
Fluid Inclusions ◽  
Hanging Wall ◽  
Oscillatory Zoning ◽  
Stage Iii ◽  
Fine Grained ◽  
Melting Temperatures ◽  
Homogenization Temperatures ◽  
Intrusive Suite ◽  
Cathodoluminescence Imaging

ABSTRACT The Deer Horn deposit, located 150 km south of Smithers in west-central British Columbia, is an Eocene polymetallic system enriched in Au-Ag-Te with lesser amounts of Bi-Pb-W; the Au and Ag are hosted in Te-bearing minerals and Ag-rich gold (Au-Ag alloy). A quartz-sulfide vein system containing the main zones of Au-Ag-Te mineralization and attendant sericite alteration occurs in the hanging wall of a local, spatially related thrust fault and is genetically related to the nearby Eocene Nanika granodiorite intrusive suite. Tellurium-bearing minerals commonly form isolated euhedral to subhedral grains or composite grains (up to 525 μm in size) of Ag-, Bi-, Pb-, and Au-rich tellurium-bearing minerals (e.g., hessite, tellurobismuthite, volynskite, altaite, and petzite). Panchromatic cathodoluminescence imaging revealed four generations of quartz. Within remnant cores of quartz I, local oscillatory zoning occurs in quartz II. Fine-grained veinlets of quartz III and IV crosscut quartz I and II, showing evidence of at least two deformation events; late-forming veinlets of calcite crosscut all generations of quartz. The tellurides and Ag-rich gold occur in stage III quartz. Three types of fluid inclusions were observed in stage III and IV quartz: (1) aqueous liquid and vapor inclusions (L-V); (2) aqueous carbonic inclusions (L-L-V); and (3) carbonic inclusions (vapor-rich). Primary fluid inclusions related to the telluride mineralization within quartz III were tested with microthermometry, along with a few primary inclusions from quartz IV. Homogenization temperatures are 130.0–240.5 °C for L-V inclusions and 268.0–336.4 °C for L-L-V inclusions. Aqueous carbonic inclusions had solid CO2 melting temperatures from –62.1 to –56.8 °C, indicating the presence of ≈1 to 30 mol.% dissolved methane in these inclusions. The Deer Horn Au-Ag-Te-(Bi-Pb-W) deposit is a reduced intrusion-related gold system characterized by sheeted veins, metal zoning, low salinity aqueous-carbonic fluids, and a genetic relationship to an Eocene granodiorite. Values of δ34S of pyrite vary from –1.6 to 1.6 per mil and are compatible with a magmatic source of sulfur.

scholarly journals Genesis of the Longmendian Ag–Pb–Zn Deposit in Henan (Central China): Constraints from Fluid Inclusions and H–C–O–S–Pb Isotopes

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Xinglin Chen ◽  
Yongjun Shao ◽  
Chunkit Lai ◽  
Cheng Wang
Keyword(s):  
Fluid Inclusions ◽  
Central China ◽  
Granitic Magma ◽  
Two Phase ◽  
Quartz Veins ◽  
The North ◽  
Granitic Magmatism ◽  
Polymetallic Sulfides ◽  
Homogenization Temperatures ◽  
Stage 1

The Longmendian Ag–Pb–Zn deposit is located in the southern margin of the North China Craton, and the mineralization occurs mainly in quartz veins, altered gneissic wallrocks, and minor fault breccias in the Taihua Group. Based on vein crosscutting relations, mineral assemblages, and paragenesis, the mineralization can be divided into three stages: (1) quartz–pyrite, (2) quartz–polymetallic sulfides, and (3) quartz–carbonate–polymetallic sulfides. Wallrock alteration can be divided into three zones, i.e., chlorite–sericite, quartz–carbonate–sericite, and silicate. Fluid inclusions in all Stage 1 to 3 quartz are dominated by vapor-liquid two-phase aqueous type (W-type). Petrographic and microthermometric analyses of the fluid inclusions indicate that the homogenization temperatures of Stages 1, 2, and 3 are 198–332°C, 132–260°C, and 97–166°C, with salinities of 4.0–13.3, 1.1–13.1, and 1.9–7.6 wt% NaCleqv, respectively. The vapor comprises primarily H2O, with some CO2, H2, CO, N2, and CH4. The liquid phase contains Ca2+, Na+, K+, SO42−, Cl−, and F−. The sulfides have δ34S=–1.42 to +2.35‰ and 208Pb/204Pb=37.771 to 38.795, 207Pb/204Pb=15.388 to 15.686, and 206Pb/204Pb=17.660 to 18.101. The H–C–O–S–Pb isotope compositions indicate that the ore-forming materials may have been derived from the Taihua Group and the granitic magma. The fluid boiling and cooling and mixing with meteoric water may have been critical for the Ag–Pb–Zn ore precipitation. Geological and geochemical characteristics of the Longmendian deposit indicate that the deposit is best classified as medium- to low-temperature intermediate-sulfidation (LS/IS) epithermal-type, related to Cretaceous crustal-extension-related granitic magmatism.

Diagenetic palaeotemperatures from aqueous fluid inclusions: re-equilibration of inclusions in carbonate cements by burial heating

1987 ◽  
Vol 51 (362) ◽  
pp. 477-481 ◽  
Author(s):  
R. C. Burruss
Keyword(s):  
Fluid Inclusions ◽  
Confining Pressure ◽  
Homogenization Temperature ◽  
Aqueous Fluid ◽  
Temperature History ◽  
Maximum Temperature ◽  
Carbonate Cements ◽  
Trapping Temperature ◽  
Observed Behaviour ◽  
The Common

AbstractDiagenetic palaeotemperatures determined from aqueous fluid inclusions can be affected by re-equilibration during burial heating. Calculations based on the observed behaviour of inclusions in fluorite under external confining pressure allows prediction of the temperatures and depths of burial necessary to initiate re-equilibration of aqueous inclusions in the common size range 40 to 4 µm. Heating of 20° to 60°C over the initial trapping temperature may cause errors of 10° to 20°C in the homogenization temperature. This suggests re-equilibration may cause aqueous inclusions in carbonates to yield a poor record of their low-temperature history, but a useful record of the maximum temperature experienced by the host rock. Previous work suggests inclusions containing petroleum fluids will be less susceptible to re-equilibration.

HIGH RESOLUTION PALAEOGEOGRAPHIC MAPPING OF THE FLUVIAL-LACUSTRINE PATCHAWARRA FORMATION IN THE COOPER BASIN, SOUTH AUSTRALIA

2002 ◽  
Vol 42 (1) ◽  
pp. 65 ◽  
Author(s):  
P.C. Strong ◽  
G.R. Wood ◽  
S.C. Lang ◽  
A. Jollands ◽  
E. Karalaus ◽  
...  
Keyword(s):  
High Resolution ◽  
South Australia ◽  
River System ◽  
Structural Features ◽  
Gas Reservoirs ◽  
Predictive Tool ◽  
Sequence Stratigraphic ◽  
Channel Belt ◽  
Reservoir Connectivity ◽  
Cooper Basin

Fluvial-lacustrine reservoirs in coal-bearing strata provide a particular challenge for reservoir characterisation because of the dominance of coal on the seismic signature and the highly variable reservoir geometry, quality and stratigraphic connectivity. Geological models for the fluvial gas reservoirs in the Permian Patchawarra Formation of the Cooper Basin are critical to minimise the perceived reservoir risks of these relatively deep targets. This can be achieved by applying high-resolution sequence stratigraphic concepts and finescaled seismic mapping. The workflow begins with building a robust regional chronostratigraphic framework, focussing on widespread lacustrine flooding surfaces and unconformities, tied to seismic scale reflectors. This framework is refined by identification of local surfaces that divide the Patchawarra Formation into high-resolution genetic units. A log facies scheme is established based on wireline log character, and calibrated to cores and cuttings, supported by analogue studies, such as the modern Ob River system in Western Siberia. Stacking patterns within each genetic unit are used to determine depositional systems tracts, which can have important reservoir connectivity implications. This leads to the generation of log signature maps for each interval, from which palaeogeographic reconstructions are generated. These maps are drawn with the guiding control of syn-depositional structural features and net/ gross trends. Estimates of fluvial channel belt widths are based on modern and ancient analogues. The resultant palaeogeography maps are used with structural and production data to refine play concepts, as a predictive tool to locate exploration and development drilling opportunities, to assess volumetrics, and to improve drainage efficiency and recovery during production of hydrocarbons.

BREATHING NEW LIFE INTO THE EASTERN DAMPIER SUB-BASIN: AN INTEGRATED REVIEW BASED ON GEOPHYSICAL, STRATIGRAPHIC AND BASIN MODELLING EVALUATION

2004 ◽  
Vol 44 (1) ◽  
pp. 123 ◽  
Author(s):  
G.P. Thomas ◽  
M.R. Lennane ◽  
F. Glass ◽  
T. Walker ◽  
M. Partington ◽  
...  
Keyword(s):  
Seismic Data ◽  
Joint Venture ◽  
Velocity Model ◽  
Upper Jurassic ◽  
Source Rocks ◽  
Third Order ◽  
Geochemical Fingerprinting ◽  
Stratigraphic Framework ◽  
Seismic Image ◽  
Hydrocarbon Charge

The eastern Dampier Sub-basin on Australia’s northwestern margin has been subject to intensive exploration activity since the early 1960s. The commercial success rate for exploration drilling, however, has been a disappointing 8%, despite numerous indications of at least one active petroleum system. During 2002–2003, Woodside and its joint venture partners undertook an integrated review of the area, aimed at unlocking its remaining potential. Stratigraphy, hydrocarbon charge and 3D seismic data quality were addressed in parallel.The eastern Dampier Sub-basin stratigraphy was upgraded from the existing, conventional, second-order tectono-stratigraphic framework to a third-order, exploration-scale, genetic stratigraphic framework. The new framework has regional predictive capability in terms of reservoir (and seal) presence and facies, and has led to recognition of new plays and an enhanced understanding of known plays. One new play involves shoreface sands within the Calypso Formation. New light has been shed on the known Lower Cretaceous M.australis sands play (K30), by the creation of gross depositional environment maps at third-order sequence scale. The Upper Jurassic deepwater clastics play of the Lewis Trough has also been developed, by recognition of four prospective, sand-rich gravity-flow intervals in the early Oxfordian (J42 play).A 3D charge modelling study, underpinned by new geochemical analysis, has allowed delineation of areas of higher and lower risk in terms of hydrocarbon charge and phase (oil versus gas). Key source rocks for oil are identified in the early Oxfordian W.spectabilis biozone, although they are also a likely source for gas in the southwest of the area. The Bathonian-Callovian Upper Legendre Formation is a major source for gas, but could also have contributed minor oil in the northeast of the area. By a combination of geochemical fingerprinting and 3D forward modelling, most hydrocarbon occurrences in the area have been tied to these source intervals, complete with a consistent view of maturities and migration pathways.Some 1,500 km2 of the Panaeus multi-client 3D survey were reprocessed, with close attention to multiple removal, velocities and imaging. A step-change improvement in seismic quality was obtained, together with improved velocities for depth conversion.The prospect portfolio has been polarised and much enhanced through these studies, and the results of several existing wells have become better understood. Some new prospects were identified by apparent direct fluid indications, detected in one case by 3D volume AVO screening. Other new prospects are the result of a clearer seismic image, or of the revised velocity model for depth conversion. New plays are still being followed up, while the fresh light cast on existing plays (e.g. K30 and J42), in combination with improved seismic data, has led to development of several interesting opportunities.

scholarly journals Genesis of the Zhijiadi Ag-Pb-Zn Deposit, Central North China Craton: Constraints from Fluid Inclusions and Stable Isotope Data

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-23 ◽  
Author(s):  
Tao Liu ◽  
Suo-Fei Xiong ◽  
Shao-Yong Jiang ◽  
Hua-Liang Li ◽  
Qi-Zhi Chen ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
North China Craton ◽  
North China ◽  
Early Stage ◽  
Homogenization Temperature ◽  
Main Stage ◽  
Magmatic System ◽  
Hydrothermal Deposit ◽  
Homogenization Temperatures ◽  
Late Stages

The Zhijiadi Ag-Pb-Zn deposit is located in the central North China Craton. Fluid inclusions (FIs) studies indicate three types of FIs, including aqueous, aqueous-carbonic, and daughter mineral-bearing multiphase inclusions. The daughter minerals in FIs are mainly composed of marcasite, chalcopyrite, calcite, and dolomite. Microthermometric data show that the homogenization temperature and salinity of FIs decrease gradually from early to late stages. Homogenization temperatures from early to main to late stages span from 244 to 334°C, from 164 to 298°C, and from 111 to 174°C, respectively, while their salinities are 4.0–9.9 wt.% NaCl equiv., 0.5–12.7 wt.% NaCl equiv., and 0.2–8.8 wt.% NaCl equiv., respectively. Trapping pressures drop from 203–299 MPa (the early stage) to 32–158 MPa (the main stage). The dropping of pressure and temperature and mixing and/or dilution of ore-forming fluids result in the formation of ore deposit. Combined with C-O-S-Pb isotopic compositions, the initial ore-forming fluids and materials were likely derived from a magmatic system. As a whole, we proposed that this deposit belongs to medium-low temperature hydrothermal deposit related to volcanic and subvolcanic magmatism strictly controlled by the fault zones.

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