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Kansas
PSDM for Unconventional Reservoirs? A Niobrara Shale Case Study
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)
Summary As of this writing, unconventional resource plays absorb a significant proportion of onshore U.S. E&P budgets. The perceived simplicity and homogeneity of unconventional reservoirs explained their initial appeal to firms seeking to reduce "dry hole risk". However, as inconsistent drilling results from many resource plays highlight, shale reservoirs are neither simple nor homogeneous. Used infrequently 5-10 years ago, drillers today commonly employ 3D seismic to improve horizontal well "geosteering". Explorers also increasingly rely on 3D seismic to delineate productive "sweet spots". In particular, differential horizontal stress (from azimuthal anisotropy analysis) and elastic inversion for "brittleness" are paired to find optimal drill locations and wellbore orientation (Sena et al., 2011). While prestack depth migration (PSDM) is commonly applied in "complex" plays such as the sub-salt Gulf of Mexico, it has been adopted in resource plays at a slow (but accelerating) pace. PSDM promises two major "structural" benefits over conventional time imaging: · More accurate geologic dips between well control · Crisper and better positioned view of faulting Additionally, in areas that exhibit velocity complexity, seismic anisotropy, and dipping beds, PSDM can provide more accurate input for most attribute technologies. We present a case study from a wide-azimuth 50 mi survey acquired in the Niobrara Shale. While the study area exhibits mildly dipping beds, a significant shallow lateral velocity variation motivates the use of PSDM to correct event dips and improve the focusing of faults. Vertical mistie correction predicted the top Niobrara to within 4 feet on a new well, but we show enough variation in Thomsen d to justify anisotropic PSDM. Azimuthal velocity analysis using Wave Equation PSDM (WEM) azimuth angle gathers indicates a very weak level of overburden azimuthal anisotropy. However, we show that amplitude versus azimuth (AVAZ) may better measure differential horizontal stress in the target interval. We show that the contrast in Young’s Modulus across the Niobrara has significant azimuthal variations, implying a distinct preferred direction in terms of stiffness.
- North America > United States > Wyoming (0.85)
- North America > United States > Kansas (0.85)
- North America > United States > Colorado (0.85)
- North America > United States > Nebraska (0.71)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.71)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Anisotropy (0.48)
- North America > United States > Wyoming > Laramie Basin > Niobrara Formation (0.99)
- North America > United States > Nebraska > Laramie Basin > Niobrara Formation (0.99)
- North America > United States > Kansas > Thomsen Field (0.99)
- (3 more...)
- Well Drilling > Drilling Operations (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Management > Energy Economics > Unconventional resource economics (1.00)
Niobrara Fracture Prospecting Through Integrated Structural and Azimuthal Seismic Interpretation, Silo Field Area, Wyoming
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.
- Geology > Structural Geology > Fault (0.53)
- Geology > Geological Subdiscipline > Geomechanics (0.38)
- North America > United States > Wyoming > Silo Field (0.99)
- North America > United States > Wyoming > Niobrara Formation (0.99)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- (13 more...)
Understanding Production Drivers and Challenges in Converting a Vertical to Horizontal Oil Play Utilizing Single Well Modeling
Gonzales, Veronica M. (Schlumberger) | Barham, Michael (Helis Oil & Gas) | Lawless, Paul (Helis Oil & Gas) | Cherian, Bilu V. (Schlumberger) | Mata, Domingo (Schlumberger) | Higgins-Borchardt, Shannon (Schlumberger) | Alatrach, Samer (Schlumberger)
Abstract The recent growth in horizontal well technology has resulted in existing oil and gas vertical development plays to be evaluated for horizontal well applicability. As operators attmept to evaluate the criteria for converting from vertical well plays to horizontal well plays, sound data gathering and modeling become crucial to understand how completion strategies needs to be modified for improved production, without utilizing an expensive trial and error methodology. The Powder River basin contains a variety of producing shales and sands currently being explored for vialibility (i.e. Niobrara, Frontier, etc). In this study, reservoir and fracture properties are estimated based on hydraulic fracture modeling, rate-transient analysis techniques and production history matching to calibrate log data measurements. The challenges associated with calibration and modeling measurements from petrophysical and rock mechanics models are compared with hydraulic fracture and production modeling results to understand the direction of optimization and future basin growth. Past experiences are typically the basis for design and implementation of developing a new drilling and completion program. Interpretation of the hydraulic fracture behavior is often inferred from simple diagnostics, and as production ensues the repeatability for success or failure is often attributed to modifying the hydraulic fracturing program or geological influences, which is subject to inconsistency and qualitative introspection. Within this study a single well modeling approach is utilized to understand fracture geometry, correlate this with production history matching results, and distinguish production attribution from hydraulic fracture characteristics or reservoir properties. Exercising this workflow addresses challenges affiliated with modeling fracture propagation and production matching and the gap associated with horizontal well development in existing vertical plays.
- North America > United States > Wyoming (0.51)
- North America > United States > Montana (0.50)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.37)
- North America > United States > South Dakota > Williston Basin (0.99)
- North America > United States > North Dakota > Williston Basin (0.99)
- North America > United States > Montana > Williston Basin (0.99)
- (7 more...)
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.”
- North America > United States > Colorado > Weld County (0.71)
- North America > United States > Colorado > Larimer County (0.46)
- North America > United States > Colorado > Denver County (0.46)
- (3 more...)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.88)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.66)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Limestone (0.45)
- North America > United States > Wyoming > Sand Wash Basin (0.99)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Wyoming > Niobrara Formation (0.99)
- (31 more...)