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Treadgold, Galen (Global Geophysical Services) | Eisenstadt, Gloria (Global Geophysical Services) | Maher, John (Global Geophysical Services) | Fuller, Joe (Global Geophysical Services) | Campbell, Bruce (Global Geophysical Services)
Rock property analysis of the A large multi-client, full-azimuth 3D seismic survey of Niobrara involved processing the 3D to address both layer almost 800 square miles in southeastern Wyoming is the and azimuthal anisotropy, creating gathers with reliable far basis for a regional structural interpretation and azimuthal offset amplitudes for an elastic inversion. Initial analysis of velocity analysis of the Niobrara in the area of the Silo the layer anisotropy was performed on isotropicly migrated Field, in the northern end of the Denver-Jules Basin. The gathers using a simultaneous picking tool for velocity and unconventional Niobrara oil and gas play has been VTI (vertical transverse isotropy). VTI information was compared to the Bakken in North Dakota but variable well then used to update traveltimes and begin scanning for HTI results have long plagued operators. Silo Field has (horizontal transverse isotropy). The approach used to produced about 10 million barrels of oil since 1981 but well define the HTI involved migrating the gathers rates can vary drastically over a short distance. The study approximately 100 times to test the impact of small integrates seismically derived rock attributes, well and changes in azimuthal anisotropy (as expressed by elliptical production data, and integrated regional structural migration operators). The migration scanning result was interpretation to understand the Niobrara fracturing and to used to once again update 1-D travel times feeding a reduce drilling risk.
This study focuses on the application of carbon isotope and elemental stratigraphy to the Greenhorn - Carlile - Niobrara Formation interval, with analysis of seven cores in the Denver Basin and one core in the Washakie Basin. Carbon isotope stratigraphy has been shown to exhibit lithology independent chronostratigraphic correlative capabilities with the potential to provide local, regional, and global chronostratigraphic correlations. Carbon isotope data gathered from two Niobrara cores, one at six-inch sampling intervals and the other at two-foot intervals by Stout (2012), are used as a high-resolution pilot data set from which to build on. Recently collected carbon isotope data, sampled at two- and three-foot intervals along a 560-foot Greenhorn - Carlile - Niobrara core, present the first continuous carbon isotope profile of this scale and resolution for Late Cretaceous stratigraphy in the Denver Basin. Four more Greenhorn - Carlile - Niobrara cores will be sampled for carbon and oxygen isotopes. The carbon isotope profiles will be used as chronostratigraphic markers for intra- and inter-basinal correlations. Preliminary results clearly show correlative carbon isotope excursions among the cores.
Elemental stratigraphy has many applications including chemostratigraphic correlation, a proxy for mineralogy/lithology, and a proxy for water column conditions (e.g. redox potential) during the time of deposition (Tribovillard et al., 2006; Ratcliffe & Wright, 2012). Elemental analysis has particular merit in the study of mudstones such as those of the Greenhorn - Carlile - Niobrara Formation interval, with the ability to reveal geochemical trends in fine-grained, relatively homogeneous lithologies. The handheld energy-dispersive x-ray fluorescence (ED-XRF) analyzer is a modern tool capable of rapid, in situ measurements for elements greater than or equal to magnesium in atomic weight. The handheld ED-XRF analyzer has made high-resolution elemental stratigraphy a viable and even practical consideration. Elemental analysis was conducted by handheld ED-XRF analyzer on the same core suite as those sampled for carbon isotopes, at a sampling interval of one foot. Preliminary results show that particular elemental trends directly correspond to mineralogy/lithology and can be divided into distinct chemostratigraphic packages.
Brown, Morgan P. (Wave Imaging Technology Incorporated) | Higginbotham, Joseph H. (Wave Imaging Technology Incorporated) | Macesanu, Cosmin M. (Wave Imaging Technology Incorporated) | Ramirez, Oscar E. (Wave Imaging Technology Incorporated) | List, Dave (Fidelity E&P Company) | Lang, Chris (Fidelity E&P Company)
The Niobrara Shale in the United States has ramped up into a hot play that could soon bring an explosion of horizontal drilling in Colorado and Wyoming. The combination of horizontal drilling and multistage hydraulic fracturing is transforming the Niobrara from a target that has been drilled vertically and primarily for gas for nearly 100 years into a liquids-rich play that is capturing considerable attention. Speaking at the 2011 SPE Annual Technical Conference and Exhibition in Denver, John Ford, general manager of Colorado’s Wattenberg field at Anadarko, described the growing Niobrara activity as “really the next big thing.”
That optimism was understandable. In November, Anadarko announced that its leases at Wattenberg may hold more than a billion barrels of recoverable oil and natural gas. The statement noted company drilling success in 11 recent wells at the field, including the Dolph 27-1HZ horizontal well that showed initial production of more than 1,100 B/D of oil and 2.4 MMcf/D of natural gas. These latest wells have given the company confidence that it can drill between 1,200 and 2,700 wells in northeast Colorado, with approximately 160 wells planned for this year. Based on results so far, the company expects ultimate recovery of between 500 million and 1.5 billion bbl of oil, natural gas liquids, and natural gas on an equivalent basis.
Anadarko is not alone. Chesapeake Energy, Noble, Encana, and EOG Resources are among the largest acreage holders and the most active drillers of many companies—including numerous small independents—probing the Niobrara. Majors such as Shell and Marathon Oil have significant acreage.
There are more than 50 operators in or near the Wattenberg field alone. Situated north/northeast of the Denver area, Wattenberg is the largest producing field in the Denver-Julesburg (D-J) Basin and one of the largest onshore oil and gas fields in the US.
Reservoir Rock and Producing Regions
Although the Niobrara is usually referred to as a shale, its reservoir rock consists primarily of limestone or chalk intervals, said Steve Sonnenberg, professor of petroleum geology at Colorado School of Mines in a recent edition of the AAPG Explorer (published by the American Association of Petroleum Geologists). “The formation demonstrates facies changes that range from limestone and chalk in the eastern end to calcareous shale in the middle and eventually transitioning to sandstone farther west,” said Sonnenberg, a past president of AAPG. “Depth and thickness are highly variable.”