Recently Added in Bulletin

Borehole breakouts do not give an accurate measurement of in situ stress orientation in fractured tight reservoirs. An example is the discrepancy between the maximum horizontal principal compression stress derived from various methods in the Eocene Hetaoyuan Formation, Nanxiang Basin China

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Multidisciplinary interpretation of borehole images, cores, wireline logs, and seismic data is crucial to the construction of the regional transportation systems and the stratigraphic correlation in the Xujiahe Formation, Sichuan Basin, China. Three major sedimentary systems have been identified.

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Facies variations of source rock were determined from molecular and compound specific isotopic composition of the n-alkanes in oil from the Central Sumatra Basin. This study shows the variability of depositional environments that could generate potential source rock intervals.

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Pore structures of carbonate rock are quantified using multiscale digital image analysis. Mercury injection capillary pressure measurements are used to assess pore throat properties. The quantified pore structure parameters are correlated to plug measurements of electrical resistivity and permeability.

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Feldspar dissolution and precipitation of clay and quartz cements affect reservoir quality in sandstones with detrital feldspar. This paper evaluates their impact on two Eocene fan delta sandstones in Bohai Bay Basin, China.

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Carbonate buildups in Central Luconia, offshore northwest Borneo, display complex seismic geomorphologies formed in response to high frequency, high-amplitude oscillation of sea level and periodic incursions of siliciclastics. These results have implications for petroleum exploration and production.

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Based on a study of 51 coal samples, pores in coals can be divided into plant tissue hole, blowhole, dissolved pore, and intercrystalline pore. Pore structure can be opened, semi-closed, and ink bottle.” The total pore volume shows a positive relationship with the total specific surface area.

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Critical factors related to topographic, geologic, and hydrologic features are important for the creation and preservation of underpressure present in the Midcontinent of the United States. One of these areas is the large, highly saline brine plume of western Oklahoma and Kansas.

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A flexible, object-based rock reconstruction algorithm reproduces the microscale micritic fabrics of microporous carbonates. Results quantify the importance of micropores in contributing to or controlling overall flow and sweep characteristics in such fabrics.

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Borehole images are useful for in-depth characterization of fluvial deposits in the Upper Cretaceous of the Piceance Basin, Colorado. This procedure is especially useful in the reconstruction of paleomorphology, flow, regime, and fluvial architecture.

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Recently Added in Interpretation
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Recently Added in Environmental Geosciences

Net fluid production and pressure data were gathered to estimate the amount of CO2 storage space available and the potential for additional oil recovery using CO2-enhanced oil recovery (EOR) in the Phacoides sandstone, McKittrick oilfield, San Joaquin Valley, California. 

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One of the challenges confronting carbon dioxide capture and sequestration (CCS) in geologic media over extended periods of time is determining the caprock sealing capacity. If the pressure of supercritical carbon dioxide (scCO2) injected in the repository overcomes the caprock sealing capacity, leaking of scCO2 may enter other porous formations, compromising the storage formation, or even may go back to the atmosphere, and thus the process of sequestration becomes futile.

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Examination of historical water-quality data (major cations and anions and total dissolved solids [TDS]) for Rock Creek, located in eastern Nebraska’s saline wetlands north of the Platte River, revealed that concentrations of sodium (Na), chloride (Cl), and TDS increased significantly in the downstream reach below the town of Ceresco, exceeding the U.S. Environmental Protection Agency (USEPA) secondary drinking water standards of 250 mg/L for Cl and 500 mg/L for TDS.

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This study simulated the injection of supercritical phase CO2 into the South Georgia Rift (SGR) basin to evaluate the feasibility of long-term storage. Because of the lack of basin data, an equilibrium model was used to estimate the initial hydrostatic pressure, temperature, and salinity gradients that represent our study area. 

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We use sediment ages and mercury (Hg) concentrations to estimate past and future concentrations in the South River, Virginia, where Hg was released between 1930 and 1950 from a manufacturing process related to nylon production. In a previous study, along a 40 km (25 mi) reach, samples were collected from 26 of 54 fine-grained deposits that formed in the lee of large wood obstructions in the channel and analyzed for grain size, Hg concentration, and organic content. We also obtained radiometric dates from six deposits. To create a history that reflects the full concentration distribution (which contains concentrations as high as 900 mg/kg [900 ppm]), here, we treat the deposits as a single reservoir exchanging contaminated sediments with the overlying water column, and assume that the total sediment mass in storage and the distribution of sediment ages are time invariant. We use reservoir theory to reconstruct the annual history of Hg concentration on suspended sediment using data from our previous study and new results presented here. Many different reconstructed histories fit our data. To constrain results, we use information from a well-preserved core (and our estimate of the total mass of Hg stored in 2007) to specify the years associated with the peak concentration of 900 mg/kg. Our results indicate that around 850 kg (1874 lb) of Hg was stored in the deposits between 1955 and 1961, compared to only 80 kg (176 lb) today. Simulations of future Hg remediation suggest that 100-yr timescales will be needed for the South River to remove Hg-contaminated sediments from the channel perimeter through natural processes.
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 SONAR, historical and aerial photographs, and vibracoring were used to assess the type and thickness distribution of sediments impounded by Gold Ray Dam on the Rogue River in southern Oregon. From these data, a volume of about 400,000 cubic yards (

Equation EG13006eq1

) of sediment was determined for the inundated area of the reservoir.

Overall, sediment volumes in the impounded part of the reservoir were less than expected. There are three possibilities that may explain the perceived absence of sediment: (1) the gradient of the Rogue River in this stretch is less, and therefore sediment yields are less; (2) the extraction of gravels and/or other impediments upstream decreased the availability of sediments delivered into the reservoir; and/or (3) sediment was deposited by a prograding delta that filled in the inundated area of the floodplain upstream from Gold Ray Dam. The amount of sediment deposited on this inundated floodplain may have been as much as 1,800,000 cubic yards (Equation EG13006eq2), bringing the total amount of sediment impounded by Gold Ray Dam to Equation EG13006eq3 yards (Equation EG13006eq4).

Applied sedimentology is not only vital to developing a depositional model for the filling of a reservoir, but also providing insights into depositional and erosional changes that will occur upon the removal of a dam. In particular, the processes of delta formation, reoccupation of abandoned channels, and avulsion are paramount in determining sediment accumulation and distribution in reservoirs.

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Shales are becoming the most important source of natural gas in North America, and replacement of coal by natural gas is reducing CO2 emissions and improving air quality. Nevertheless, shale gas is facing strong opposition from environmental nongovernmental organizations. Although these organizations have greatly exaggerated the potential negative environmental impacts of shale gas and shale oil, methane leakage and contamination of groundwater and surface water by flowback and produced waters are serious concerns. These contamination pathways are not unique to shale gas and shale oil, and they are manageable.
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The West Virginia Division of Energy is currently evaluating several deep saline formations in the Appalachian Basin of West Virginia that may be potential carbon dioxide (CO2) sequestration targets. The Silurian Newburg Sandstone play, developed in the 1960s and 1970s, primarily involved natural-gas production from reservoir rock with well-developed porosity and permeability. High initial pres-sures encountered in early wells in the Newburg indicated that the overlying Silurian Salina Formation provides a competent seal. Be-cause of the large number of CO2 point sources in the region and the favorable reservoir properties of the formation (including an esti-mated 300 bcf of natural-gas production), the Newburg Sandstone was evaluated for the potential geologic storage of CO2. Within the Newburg play, there are several primary fields separated geographi-cally and geologically by saltwater contacts and dry holes. Previous studies have determined the storage potential within these individual fields. This study shows that the Newburg is more suitable for small-scale injection tests instead of large-scale regional storage operations.
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