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Collaborating Authors
2013 SEG Annual Meeting
Seismic Methodology for Identification of Highly Profitable Wells in Fractured-Vuggy Carbonates in the Tarim Basin
Ping, Yang (BGP, CNPC) | Haiyin, Li (BGP, CNPC) | Guangjian, Dan (BGP, CNPC) | Xianghao, Liang (Tarim Oilfield Company, Petrochina) | Qing, Miao (Tarim Oilfield Company, Petrochina) | Bing, Jing (Tarim Oilfield Company, Petrochina)
Summary It is a long-lasting challenge that in the fractured-vuggy carbonates of the Tarim Basin, the production rates of the wells are usually very high at the beginning but decline very fast. Our studies show that the high and stable yielding wells can be located after the reserve of each fracture-cave unit has been assessed based on proper seismic methodology. That methodology consists of three core techniques: the full-azimuth and high-density acquisition, the amplitude-preserved prestack depth migration, and the quantitative reservoir characterization. Based on these techniques, the fracture-cave units can be delineated and the big oil-bearing units are selected as the drilling targets. By this way, the ratio of highly profitable wells versus total wells drilled increases significantly, and optimizes the development plan of the field.
Summary In many pore pressure predictions, the differential pressure rather than the effective pressure is estimated from velocity measurements as a value of 1 is assumed for the effective pressure coefficient n. In this study n is calibrated with well-log data in two different Gulf of Mexico (GOM) pressure regimes that represent compaction disequilibrium and unloading/clay digenesis processes. Values for n in abnormal pressure zones are approximately 0.83. For extending the results to areas where there is insufficient well control to calibrate n, n is inverted from Gassmann's equation.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Mineral > Silicate > Phyllosilicate (0.50)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.33)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.92)
- Well Drilling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Furthermore, the FMM can be used for computing the traveltimes and raypaths of To compute traveltimes and raypaths of seismic waves of the multiply reflected and transmitted seismic waves when different types in ocean regions with complex seabed it is implemented in a multistage way (Raulinson and topography, a new method, called multistage upwind Sambridge, 2004). However, the conventional upwind interpolation method, is presented. The key point of the finite difference scheme is not suitable for the irregular method is to construct the linear interpolation formulas for grid. As a result, the FMM cannot be used directly in the traveltimes and raypaths by using the basic ideas of the mountainous regions with complex surface topography upwind finite difference method, the multistage fast (Sun, et al., 2011). The same is true when the FMM is used marching method, and of the multistage backward ray in ocean regions with the complex seabed topography.
High-Resolution Interpretation of Sonic Logging Measurements Using Stochastic Inversion With Spatial Slowness Sensitivity Functions
Huang, Shan (The University of Texas at Austin) | Yang, Qinshan (The University of Texas at Austin) | Matuszyk, Pawel J. (The University of Texas at Austin) | Torres-Verdín, Carlos (The University of Texas at Austin)
Summary Sonic logging tools excite compressional, shear, and different dispersive modes in a wellbore. Waveforms acquired at the receiver array are processed to calculate compressional and shear slowness logs, from which one can estimate relevant dynamic elastic properties of rock formations surrounding the borehole. Shoulder-bed effects often influence the interpretation of sonic logging measurements when the tool operates across formations with thin beds. To address that challenge, we introduce a new method that reduces shoulder-bed effects and provides a high resolution shear slowness log. At several discrete frequencies, the method uses stochastic inversion to match simulated flexural mode slownesses with those obtained from processed field data. The method gives accurate results with quantitative indicators of parameter uncertainty. Axial spatial slowness sensitivity functions are used for forward modeling, which significantly reduces computation time. We apply the new method to a synthetic case and obtain accurate and stable shear slowness estimations. In a field case, the inverted results not only correlate well with the original log, but also provide an enhancement in vertical resolution.
Instantaneous 4D Seismic (I4D) for Offshore Water Injection Monitoring
Hatchell, Paul (Shell International Exploration and Production Incorporated) | Wang, Kanglin (Shell International Exploration and Production Incorporated) | Lopez, Jorge (Shell International Exploration and Production Incorporated) | Stammeijer, Jan (Shell Upstream Americas) | Davidson, Mark (Shell Upstream Americas)
Summary "Instantaneous 4D (i4D)" is a new method which aims to acquire dedicated high-quality 4D data with short turn-around time at cost levels low enough to make it affordable to repeat such data acquisition programs reasonably frequently. This method enables monitoring of fast reservoir changes such as those occurring in the vicinity of water injection wells. The method does not replace conventional full-field 4D monitoring but is designed to fill in the interval between conventional surveys and balance long-term versus short-term monitoring needs. We expect this technology to become important in offshore hydrocarbon fields with rapid changes due to water injection.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.88)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Four-dimensional and four-component seismic (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
Summary Stampede field, formerly known as Pony-Knotty Head field, is a sub-salt Miocene discovery in the deepwater, Gulf of Mexico. Although it is a well imaged structure, development and production requirements warranted an improved image over the field. From the discovery through field development, a variety of seismic data such as NAz (Narrow Azimuth), WAz (Wide Azimuth) and Dual Coil (Full Azimuth or FAz) have been used to meet these requirements. In this paper, we are going to present improvements in imaging at the Stampede field over time and discuss issues and challenges in sub-salt imaging in general.
- North America > United States > Gulf of Mexico > Central GOM (1.00)
- North America > United States > North Dakota > Burke County (0.89)
- North America > United States > Montana > Richland County (0.89)
- North America > United States > Colorado > Logan County (0.89)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.98)
- Geophysics > Seismic Surveying > Seismic Processing (0.70)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Green Canyon > Block 512 > Stampede Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Green Canyon > Block 511 > Stampede Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Green Canyon > Block 468 > Stampede Field (0.99)
SUMMARY The nonlinearity of the seismic amplitude-variation-with-offset (AVO) response in the presence of large relative changes in acoustic and elastic medium properties is investigated with physical modelling data. A procedure for pre-processing reflection data, acquired using the CREWES-University of Calgary physical modelling facility, is enacted on a reflection from a water/plexiglas boundary. The resulting picked and processed amplitudes are compared with exact solutions of the plane-wave Zoeppritz equations, as well as first, second, and third order RPP approximations. We conclude that in the angle range 0-20°, the third order plane wave approximation is sufficient to capture the nonlinearity of the AVO response to within roughly 1% from a liquid-solid boundary with VP, VS and ? contrasts of 1485-2745m/s, 0-1380m/s, and 1.00-1.19gm/cc respectively. This is in contrast to the linear Aki-Richards approximation, which is in error by as much as 25% in the same angle range.
Summary The Devonian Grosmont Formation in northeastern Alberta, Canada is the world's largest accumulation of heavy oil in carbonate rock with estimated bitumen in place of 64.5×10 m. At the study location the eroded and buried surface of the Grosmont refers as the Devonian unconformity. This unconformity is a key to the development of the Grosmont resource because the resource abuts the unconformity. Using legacy seismic data and available well log information we were able to define the Devonian unconformity as a mature karst surface within observable features such as dolines, karst valleys, karst plain, a Poljie and a ridge. The Dolines and karst valleys and other such dissolution features have the potential to erode the bitumen reservoir of the upper Grosmont members. Mapping and avoiding areas such as the dolines and karst valley are highly important for oil prospectors to increase certainty of reservoir presence.
- Geology > Rock Type > Sedimentary Rock (1.00)
- Geology > Geological Subdiscipline > Stratigraphy > Lithostratigraphy (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.76)
- North America > Canada > Saskatchewan > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > Canada > Northwest Territories > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > Canada > Manitoba > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- (2 more...)
Summary Subsurface illumination is an important consideration in survey design. Uneven illumination can distort or obscure seismic targets. Many factors affect the illumination of subsurface structures, including acquisition geometry, complex overburden shape and reflector dip angle. For a given acquisition geometry, the transformation of recording points to virtual sources allows for extended subsurface illumination for a particular shot. In marine surveys, strong surface multiples are often recorded; however, they are typically separated from primary reflections for imaging. Multiples contain information about the subsurface and have the potential for extended illumination. Injecting recorded multiples at the receiver locations essentially transforms receiver points to virtual sources in a migration. In this paper, we compare the imaging capacity of free-surface multiples using different migration kernels, a one-way and a two-way wavefield extrapolators. A two-way wavefield extrapolator overcomes the steep-dip limitation of the one-way extrapolator, at the expense of potential increase in imaging artifacts. Results from migrations using a synthetic dataset shot over the SEG Advanced Modeling Corporation (SEAM) 3D model are compared. Imaging of multiples only is compared with benchmark images of primaries only to isolate the potential of multiples for extended illumination and imaging.
Summary Over the past 20 years, ray-based post-migration reflection tomography has remained largely unchallenged as a velocity model building tool for seismic depth imaging. While other methods have been proposed, they have yet to be adopted into standard workflows. The decisive elements for such tools are: accuracy, resolution, flexibility, ease of use, and turnaround time. The success of depth domain tomography comes from the good balance it offers between those elements. This paper aims to illustrate with a few practical innovations in post migration tomography, that ray based approaches are still making progress and are nowadays finding applications far beyond their expected range of validity.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)