Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas

Loucks, Robert G.; Ruppel, Stephen C.

doi:10.1306/11020606059

Cited by 704 publications

(378 citation statements)

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“…The 120 foot long (37 m) Blakely #1core (API 42-497-33041), taken from southeastern Wise County within the Fort Worth Basin, includes part of the upper Barnett Shale (2166-2169 m below ground surface (bgs), the Forestburg Limestone (2169-218 mbgs), and the upper part of the lower Barnett Shale (2181-2202 mbgs) (Loucks and Ruppel 2007). We obtained core samples from this Blakely #1 well, courtesy of the core repository of the Texas Bureau of Economic Geology, representing five depths separated by at most 10 m: 2167 m (7109 ft; upper Barnett), 2175 m (7136 ft; Forestburg Limestone), and 2185 m (7169 ft), 2194 m (7199 ft) and 2200 m (7219 ft); all from the upper part of the lower Barnett) ( Table 2).…”

Section: Samplesmentioning

confidence: 99%

Pore structure and tracer migration behavior of typical American and Chinese shales

Liu

Gao

et al. 2015

Pet. Sci.

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With estimated shale gas resources greater than those of US and Canada combined, China has been embarking on an ambitious shale development program. However, nearly 30 years of American experience in shale hydrocarbon exploration and production indicates a low total recovery of shale gas at 12 %-30 % and tight oil at 5 %-10 %. One of the main barriers to sustainable development of shale resources, namely the pore structure (geometry and connectivity) of the nanopores for storing and transporting hydrocarbons, is rarely investigated. In this study, we collected samples from a variety of leading hydrocarbon-producing shale formations in US and China. These formations have different ages and geologic characteristics (e.g., porosity, permeability, mineralogy, total organic content, and thermal maturation). We studied their pore structure characteristics, imbibition and saturated diffusion, edge-accessible porosity, and wettability with four complementary tests: mercury intrusion porosimetry, fluid and tracer imbibition into initially dry shale, tracer diffusion into fluid-saturated shale, and high-pressure Wood's metal intrusion followed with imaging and elemental mapping. The imbibition and diffusion tests use tracer-bearing wettability fluids (API brine or n-decane) to examine the association of tracers with mineral or organic matter phases, using a sensitive and micro-scale elemental laser ablation ICP-MS mapping technique. For two molecular tracers in n-decane fluid with the estimated sizes of 1.39 nm 9 0.29 nm 9 0.18 nm for 1-iododecane and 1.27 nm 9 0.92 nm 9 0.78 nm for trichlorooxobis (triphenylphosphine) rhenium, much less penetration was observed for larger molecules of organic rhenium in shales with median pore-throat sizes of several nanometers. This indicates the probable entanglement of sub-nano-sized molecules in shales with nano-sized pore-throats. Overall findings from the above innovative approaches indicate the limited accessibility (several millimeters from sample edge) and connectivity of tortuous nanopore spaces in shales with spatial wettability, which could lead to the low overall hydrocarbon recovery because of the limited fracture-matrix connection and migration of hydrocarbon molecules from the shale matrix to the stimulated fracture network.

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Section: Samplesmentioning

confidence: 99%

Pore structure and tracer migration behavior of typical American and Chinese shales

Liu

Gao

et al. 2015

Pet. Sci.

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“…Their results show that biogenic quartz is abundant, and TOC are well correlated to quartz content and nondetrital trace element proxies (Vxs, Uxs, Nixs and Cuxs), suggesting the enrichment of organic matter in the Long-1 Member was controlled by Energies 2016, 9, 1088 5 of 24 changing paleoproductivity and bottom water redox conditions in a periodically stratified marine basin [24]. Depositional processes, productivity, and bottom water redox conditions have a profound control on the basin-wide distribution of lithofacies as well as the amount and quality of organic matter [25][26][27][28][29][30][31][32][33]. The Sichuan Basin developed on the Precambrian metamorphic basement of the upper Yangtze craton [34].…”

Section: Numbermentioning

confidence: 99%

“…Depositional processes, productivity, and bottom water redox conditions have a profound control on the basin-wide distribution of lithofacies as well as the amount and quality of organic matter [25][26][27][28][29][30][31][32][33]. The Sichuan Basin developed on the Precambrian metamorphic basement of the upper Yangtze craton [34].…”

Section: Shale Sample Preparationmentioning

confidence: 99%

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

et al. 2016

Energies

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Abstract:With the exploitation of shale gas booming all over the world, more and more studies are focused on the core technology, hydraulic fracturing, to improve commercial exploitation. Shale gas resources in China are enormous. In this research, a series of tests were carried out with samples of black organic-rich shale from the Lower Silurian Longmaxi formation, south China. Samples were drilled from different directions and were subjected to uniaxial and triaxial condition with various confining pressures, aiming at studying its rock mechanics properties, so as to provide basis for research and breakthrough of hydraulic fracturing technology. According to the results of the study, the development and distribution of shale's bedding planes significantly impact its mechanical properties. Shale samples show obvious brittle characteristics under low confining pressure, and its mechanical behavior begins to transform from brittle to plastic characteristics with increasing confining pressure. Shale samples with different inclinations (β) have different sensitivities to the confining pressure. As a result, samples with 45 • inclinations (β) are least sensitive. The strength of bedding planes is significantly lower than that of shale matrix, and tensile failure and shear failure generally tend to occur along the bedding planes. When hydraulic fracturing was conducted in shale formation with depth less than 2.25 km, corresponding to original in-situ of 60 MPa, cracks will preferably occur at first along the inclination (β) angle of 45 • from the maximum principal stress, and the failure mode is most likely to be shear failure without volumetric strain. And, different modes of failure will occur at different locations in the reservoir, depending on the orientation of bedding inclined from the principle stress, which can probably explain the phenomenon why there are fractures along and cross the bedding planes during hydraulic fracturing treatment. When hydraulic fracturing was conducted in shale formation with depth greater than 2.25 km, hydraulic fractures may not crack along the bedding surfaces to some extent.

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“…Tempestites and contour currents are more apt to redistribute muds previously deposited in the marine environment by tractive processes rather than transporting them directly into a basin. Along with the concept of hemipelagic rain in quiet waters is the corollary that environments of deposition must be 'deep;' this is supported by the fact that many shales are enriched in organic matter, indicating an anoxic environment of deposition [15]. However, anoxic waters can occur at shallow water depths, and extensive mud deposition can occur in shallow-marine mud banks [16].…”

Section: Shale Depositional Processesmentioning

confidence: 99%

“…Recent studies utilizing Field Emission Scanning Electron Microscopy (FE-SEM) coupled with incremental, argon(Ar)-ion milling of shale surfaces has revealed significant 'organo-porosity' within kerogen ( Figure 5) [15,19] This porosity is generated during the organic-maturation process that accompanies burial and hydrocarbon generation [1]. Organoporosity is by no means the only porosity within shales, nor is Ar-ion milling the only way to image pores in shales.…”

Section: Shale Porosity and Permeabilitymentioning

confidence: 99%

Important geological properties of unconventional resource shales

Slatt

2011

Open Geosciences

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Abstract:The revelation of vast global quantities of potentially productive gas and oil-prone shales has led to advancements in understanding important geological properties which impact reservoir performance. Based upon research on a variety of shales, several geological properties have been recognized as being common and important to hydrocarbon production.(1) transport/depositional processes include hemipelagic 'rain', hyperpycnal flows, turbidity current flows, tempestites , wave-reworking, and contour currents in both shallow and deep water settings. (2) Common shale minerals include clays, quartz, calcite, dolomite, apatite, and pyrite; organic constituents include spores (Tasmanites), plant remains, biogenic quartz and calcite, and arenaceous foraminifera. (3) Porosity and permeability are characteristically low with pore sizes ranging down to the nanoscale. Main pore types include intergranular (including pores within clay floccules), porous organic matter, porous fecal pellets, and microfractures. (4) Important geochemical characteristics include organic richness (>3%), maturity (>1.1%Ro for shale gas and 0.6-0.9% for shale oil) and type (I-IV), in addition to certain biomarkers which are indicators of bottom water oxicity during deposition. Remaining hydrocarbon potential [RHP = (S1 + S2)/TOC] also reflects temporal environmental changes. 'Isotopic reversals' can be used to detect best producing areas in shale-gas plays. (5) Lithofacies stacking patterns and sequence stratigraphy are the result of eustatic depositional history. A general sequence stratigraphic model is presented here that highlights this commonality. (6) Geomechanical properties are key to drilling, fracturing and production of hydrocarbons. Brittle-ductile couplets at several scales occur in shale sequences. (7) Geophysical properties, when calibrated to rock properties, provide a means of regionally to locally mapping the aforementioned properties. (8) Economic and societal considerations in the exploration and development of resource shales are garnering attention. Many potentially economic shale-gas and shale-oil plays are being identified globally. Risks and uncertainties associated with gas-and oil-rich shales include the lack of long-term production histories, environmental concerns related to hydraulic fracturing, uncertainty in calculating hydrocarbons-in-place, and fluctuations in supply, demand, and price.

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Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas

Cited by 704 publications

References 18 publications

Pore structure and tracer migration behavior of typical American and Chinese shales

Pore structure and tracer migration behavior of typical American and Chinese shales

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

Important geological properties of unconventional resource shales

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