Seismic Velocity Sensitivity Analysis: Gulf of Mexico Example, Pony Field

2010 ◽  
Author(s):  
Ryan Mann ◽  
Henry Zollinger ◽  
Steve Checkles
Keyword(s):  
Sensitivity Analysis ◽  
Gulf Of Mexico ◽  
Seismic Velocity ◽  
Velocity Sensitivity

scholarly journals Sensitivity Analysis of Seismic Velocity and Attenuation Variations for Longmaxi Shale during Hydraulic Fracturing Testing in Laboratory

Energies ◽  
2017 ◽  
Vol 10 (9) ◽  
pp. 1393 ◽  
Author(s):  
Hongyu Zhai ◽  
Xu Chang ◽  
Yibo Wang ◽  
Ziqiu Xue ◽  
Xinglin Lei ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Hydraulic Fracturing ◽  
Seismic Velocity ◽  
Longmaxi Shale

Kinematic linkage between minibasin welds and extreme overpressure in the deepwater Gulf of Mexico

2014 ◽  
Vol 2 (1) ◽  
pp. SB69-SB77 ◽  
Author(s):  
Niven Shumaker ◽  
Daniel Haymond ◽  
Joe Martin
Keyword(s):  
Gulf Of Mexico ◽  
Seismic Velocity ◽  
Large Degree ◽  
Data Sets ◽  
Seismic Velocities ◽  
Burial History ◽  
Well Control ◽  
Deep Blue ◽  
Exploration Well ◽  
Primary Section

A geopressure interpretation technique known as the seismic velocity method is a common workflow in which shale compaction functions are characterized at offset control wells, matched to interval seismic velocities, and then used to predictively calculate geopressure away from well control. The seismic velocity method is used to interpret the expected geopressure profile at the Deep Blue subsalt exploration well in Green Canyon 723 in the deep water Gulf of Mexico. The Deep Blue prospect is distinct from other prospects in the play fairway in that the prospective section is overlain by a salt withdrawal minibasin, whereas the offsetting fields are positioned either along the flanks of minibasins or under a thick allochthonous salt canopy. Predrill geopressure interpretations using numerous tomographic imaging velocity data sets shows a large degree of consistency with the magnitude of geopressure encountered in offsetting supra salt and subsalt fields. Results from the Deep Blue 1 exploration well indicate the predrill geopressure interpretation from interval seismic velocities failed to anticipate the extreme degree overpressure encountered in the subsalt section of the well due to poor deep velocity resolution and an “unloaded” compaction signature. The magnitude of overpressure in the primary section is attributed to the emplacement of an unconformable halokinetic sequence over the primary subsalt basin. An interpretive paradigm is described in which the Deep Blue pressure cell is created through two halokinetic episodes: (1) rapid progradation of a salt canopy followed by (2) subsequent salt withdrawal and emplacement of an overlying minibasin. The linkage between halokinetic sequences, burial history, and the development of overpressure can be used to predictively characterize subsalt geopressure environments.

scholarly journals Use of a Mixed-Layer Model to Investigate Problems in Operational Prediction of Return Flow

2007 ◽  
Vol 135 (7) ◽  
pp. 2610-2628 ◽  
Author(s):  
John M. Lewis
Keyword(s):  
Sensitivity Analysis ◽  
Gulf Of Mexico ◽  
Boundary Conditions ◽  
Mixed Layer ◽  
Initial Conditions ◽  
Sea Surface ◽  
Return Flow ◽  
Control Vector ◽  
Layer Model ◽  
Mixed Layer Model

Abstract Inaccuracy in the numerical prediction of the moisture content of return-flow air over the Gulf of Mexico continues to plague operational forecasters. At the Environmental Modeling Center/National Centers for Environmental Prediction in the United States, the prediction errors have exhibited bias—typically too dry in the early 1990s and too moist from the mid-1990s to present. This research explores the possible sources of bias by using a Lagrangian formulation of the classic mixed-layer model. Justification for use of this low-order model rests on careful examination of the upper-air thermodynamic structure in a well-observed event during the Gulf of Mexico Experiment. The mixed-layer constraints are shown to be appropriate for the first phase of return flow, namely, the northerly-flow or outflow phase. The theme of the research is estimation of sensitivity—change in the model output (at termination of outflow) in response to inaccuracies or uncertainties in the elements of the control vector (the initial conditions, the boundary conditions, and the physical and empirical parameters). The first stage of research explores this sensitivity through a known analytic solution to a reduced form of the mixed-layer equations. Numerically calculated sensitivity (via Runge–Kutta integration of the equations) is compared to the exact values and found to be most credible. Further, because the first- and second-order terms in the solution about the base state can be found exactly for the analytic case, the degree of nonlinearity in the dynamical system can be determined. It is found that the system is “weakly nonlinear”; that is, solutions that result from perturbations to the control vector are well approximated by the first-order terms in the Taylor series expansion. This bodes well for the sensitivity analysis. The second stage of research examines sensitivity for the general case that includes moisture and imposed subsidence. Results indicate that uncertainties in the initial conditions are significant, yet they are secondary to uncertainties in the boundary conditions and physical/empirical parameters. The sea surface temperatures and associated parameters, the saturation mixing ratio at the sea surface and the turbulent transfer coefficient, exert the most influence on the moisture forecast. Uncertainty in the surface wind speed is also shown to be a major source of systematic error in the forecast. By assuming errors in the elements of the control vector that reflect observational error and uncertainties in the parameters, the bias error in the moisture forecast is estimated. These bias errors are significantly greater than random errors as explored through Monte Carlo experiments. Bias errors of 1–2 g kg−1 in the moisture forecast are possible through a variety of systematic errors in the control vector. The sensitivity analysis also makes it clear that judiciously chosen incorrect specifications of the elements can offset each other and lead to a good moisture forecast. The paper ends with a discussion of research approaches that hold promise for improved operational forecasts of moisture in return-flow events.

Integration of seismic and gravity data — A case study from the western Gulf of Mexico

2015 ◽  
Vol 3 (4) ◽  
pp. SAC99-SAC106 ◽  
Author(s):  
Irina Filina ◽  
Nicholas Delebo ◽  
Gopal Mohapatra ◽  
Clayton Coble ◽  
Gary Harris ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Gravity Field ◽  
Gravity Model ◽  
Seismic Velocity ◽  
Gravity Data ◽  
Public Domain ◽  
Gravity Modeling ◽  
Data Sets ◽  
Gardner Equation ◽  
Well Data

A 3D gravity model was developed in the western Gulf of Mexico in the East Breaks and Alaminos Canyon protraction areas. This model integrated 3D seismic, gravity, and well data; it was constructed in support of a proprietary seismic reprocessing project and was updated iteratively with seismic. The gravity model was built from seismic horizons of the bathymetry, salt layers, and the acoustic basement; however, the latter was only possible to map in seismic data during the latest iterations. In addition, a deep layer representing the Moho boundary was derived from gravity and constrained by public-domain refraction data. A 3D density distribution was derived from the seismic velocity volume using a modified Gardner equation. The modification comprised imposing a depth dependency on the Gardner coefficient, which is constant in the classic Gardner equation. The modified coefficient was derived from well data in the study area and public-domain velocity-density data sets. The forward-calculated gravity response of the composed density model was then compared with the observed gravity field, and the mismatch was analyzed jointly by a seismic interpreter and a gravity modeler. Adjustments were then made to the gravity model to ensure that the resultant salt model was geologically reasonable and supported by gravity, seismic, and well data sets. The output of the gravity modeling was subsequently applied to the next phase of seismic processing. Overall, this integration resulted in a more robust salt model, which has led to significant improvements in subsalt seismic imaging. The analysis of the regional trend in the observed gravity field suggested that a stretched continental crust underlay our seismic reprocessing area, with an oceanic-continental transition zone located to the southeast of our reprocessing region.

scholarly journals Sensitivity Analysis in Hydrological Modeling for the Gulf of México

2016 ◽  
Vol 154 ◽  
pp. 1152-1162
Author(s):  
Sara Ibarra ◽  
Rabindranarth Romero ◽  
Annie Poulin ◽  
Mathias Glaus ◽  
Eduardo Cervantes ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Gulf Of Mexico ◽  
Hydrological Modeling
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