Prestack Seismic Analysis Research Articles

Enhanced Inter-Trace Variations Extraction via a Self-Supervised Network for Pre-Stack Seismic Analysis

Enhanced Inter-Trace Variations Extraction via a Self-Supervised Network for Pre-Stack Seismic Analysis

Introduction to this special section: Rock physics

Rock physics links the physical properties of rocks to geophysical and petrophysical observations and, in the process, serves as a focal point in many exploration and reservoir characterization studies. Today, the field of rock physics and seismic petrophysics embraces new directions with diverse applications in estimating static and dynamic reservoir properties through time-variant mechanical, thermal, chemical, and geologic processes. Integration with new digital and computing technologies is gradually gaining traction. The use of rock physics in seismic imaging, prestack seismic analysis, seismic inversion, and geomechanical model building also contributes to the increase in rock-physics influence. This special section highlights current rock-physics research and practices in several key areas, namely experimental rock physics, rock-physics theory and model studies, and the use of rock physics in reservoir characterizations.

Applications of quantitative prestack seismic analysis to unconventional resource play characterization in the Permian/Delaware Basin

The characterization of shale plays involves an understanding of tectonic history, geologic settings, reservoir properties, and the in-situ stresses of the potential producing zones in the subsurface. The associated hydrocarbons are generally recovered by horizontal drilling and hydraulic fracturing. Historically, seismic data have been used mainly for structural interpretation of the shale reservoirs. A primary benefit of surface seismic has been the ability to locate and avoid drilling into shallow carbonate karsting zones, salt structures, and basement-related major faults which adversely affect the ability to drill and complete the well effectively. More recent advances in prestack seismic data analysis yield attributes that appear to be correlated to formation lithology, rock strength, and stress fields. From these, we may infer preferential drilling locations or sweet spots. Knowledge and proper utilization of these attributes may prove valuable in the optimization of drilling and completion activities. In recent years, geophysical data have played an increasing role in supporting well planning, hydraulic fracturing, well stacking, and spacing. We have implemented an integrated workflow combining prestack seismic inversion and multiattribute analysis, microseismic data, well-log data, and geologic modeling to demonstrate key applications of quantitative seismic analysis utilized in developing ConocoPhillips' acreage in the Delaware Basin located in Texas. These applications range from reservoir characterization to well planning/execution, stacking/spacing optimization, and saltwater disposal. We show that multidisciplinary technology integration is the key for success in unconventional play exploration and development.

Noise suppression of time-migrated gathers using prestack structure-oriented filtering

Prestack seismic analysis provides information on rock properties, lithology, fluid content, and the orientation and intensity of anisotropy. However, such analysis demands high-quality seismic data. Unfortunately, noise is always present in seismic data even after careful processing. Noise in the prestack gathers may not only contaminate the seismic image, thereby lowering the quality of seismic interpretation, but it may also bias the seismic prestack inversion for rock properties, such as acoustic- and shear-impedance estimation. Common postmigration data conditioning includes running window median and Radon filters that are applied to the flattened common reflection point gathers. We have combined filters across the offset and azimuth with edge-preserving filters along the structure to construct a true “5D” filter that preserves amplitude, thereby preconditioning the data for subsequent quantitative analysis. We have evaluated our workflow by applying it to a prestack seismic volume acquired over the Fort Worth Basin, TX. The inverted results from the noise-suppressed prestack gathers are more laterally continuous and have higher correlation with well logs when compared with those inverted from conventional time-migrated gathers.

Practical aspects of AVO modeling

AVO (amplitude variation with offset) modeling contributes significantly in seismic data acquisition design, and prestack seismic data processing and interpretation. It has become a common practice in prestack seismic analysis. It is also used for verifying and developing AVO theories. Conducting AVO modeling is, by nature, an exercise of multidiscipline integration. It thus enhances reservoir characterization and reduces the risk in hydrocarbon exploration.

An empirical method for estimation of anisotropic parameters in clastic rocks

Clastic sediments, particularly shale, exhibit transverse isotropic properties with the symmetric axis perpendicular to bedding (VTI). These anisotropic rock properties are important in seismic imaging, prestack seismic analysis, and reservoir characterization. Laboratory tests are the main techniques used in measuring rock anisotropic properties. Vertical seismic profiling (VSP) and seismic refraction are the in-situ techniques used to determine anisotropic parameters. All of these methods provide significant insight to the anisotropic properties of the subsurface. However, limitations exist in the applications of these methods because of cost issues and restrictions on the number of measurements that can be conducted. Therefore, new techniques that are cost effective, easy to use, and able to measure continuous anisotropic profiles are desirable. This paper describes a methodology which involves the use of conventional rock properties to derive anisotropic rock properties.