High-resolution reservoir characterization by an acoustic impedance inversion of a Tertiary deltaic clinoform system in the North Sea

Abstract

Fluvio-deltaic sedimentary systems are of great interest for explorationists because they can form prolific hydrocarbon plays. However, they are also among the most complex and heterogeneous ones encountered in the subsurface, and potential reservoir units are often close to or below seismic resolution. For seismic inversion, it is therefore important to integrate the seismic data with higher resolution constraints obtained from well logs, whereby not only the acoustic properties are used but also the detailed layering characteristics. We have applied two inversion approaches for poststack, time-migrated seismic data to a clinoform sequence in the North Sea. Both methods are recursive trace-based techniques that use well data as a priori constraints but differ in the way they incorporate structural information. One method uses a discrete layer model from the well that is propagated laterally along the clinoform layers, which are modeled as sigmoids. The second method uses a constant sampling rate from the well data and uses horizontal and vertical regularization parameters for lateral propagation. The first method has a low level of parameterization embedded in a geologic framework and is computationally fast. The second method has a much higher degree of parameterization but is flexible enough to detect deviations in the geologic settings of the reservoir; however, there is no explicit geologic significance and the method is computationally much less efficient. Forward seismic modeling of the two inversion results indicates a good match of both methods with the actual seismic data.

Application of Spectral Decomposition and Seismic Attributes For Channel Geometry and Infill Lithology Determination: A Case Study from The Southern North Sea Basin

“…According to Figure 2, the horizon of interest is at an interval rich in sediments with gamma ray values generally greater than 70 API [45]. This is consistent with the observation of Tetyukhina, et al [8] who reported that shaly sediments with higher impedance values were deposited mainly at the bottomset of the clinoform system in the F3 block of the Southern North Sea basin.…”

“…Channels are generally visually close to or below seismic resolution [7,8], so thin to their surrounding geometry that their subtleties are nearly invisible in traditional seismic data. Thus, delineating thin reservoir sands from conventional seismic data had always been a challenge.…”

Plio-Pleistocene stratigraphic sequences and depositional model using 3D seismic interpretation constrained by well logs in Central Graben, North Sea

“…The North Sea Groups of Cenozoic era, approximately 1460 m in total thickness unconformably overlying the Chalk Group of Late Cretaceous. In North Sea region thermally subsiding basin (epicontinental basin received sediments from neighboring landmasses), were formed during Cenozoic era (Sclater and Christie 1980;Ziegler 1988;Jordt et al 1995;Sørensen et al 1997;Faleide et al 2002;Tetyukhina et al 2010;Benvenuti et al 2012;Mojeddifar et al 2015; Figure 1. Location map of F3-block: (a) subset of coordinate reference system ED50-UTM31, (b) Netherlands onshore and offshore boundaries and structural elements of the Late Jurassic-Early Cretaceous, modified after (Schroot and Schüttenhelm 2003;Kombrink et al 2012;Nelskamp et al 2012), (c) the seismic survey boundary of F3-block in blue, the location of the wells by black dots and the north-south and east-west cross sections by dashed lines.…”

Acoustic nonlinear full-waveform inversion on an outcrop-based detailed geological and petrophysical model (Book Cliffs, Utah)

“…In the oil and gas industry, inversion of seismic data is a well-known technique used for refining structural interpretation as well as for reservoir characterization (Treitel and Lines, 2001;Tetyukhina et al, 2010). With continued progress in computing power and seismic data acquisition, the seismic full-waveform inversion technique introduced by Tarantola (1984), in which all wave types including multiscattered waves are accounted for, is becoming feasible.…”