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

Abstract

Analog outcrops are commonly used to develop predictive reservoir models and provide quantitative parameters that describe the architecture and facies distribution of sedimentary deposits at a subseismic scale, all of which aids exploration and production strategies. The focus of this study is to create a detailed geological model that contains realistic reservoir parameters and to apply nonlinear acoustic full-waveform prestack seismic inversion to this model to investigate whether this information can be recovered and to examine which geological features can be resolved by this process.Outcrop data from the fluviodeltaic sequence of the Book Cliffs (Utah) are used for the geological and petrophysical twodimensional model. Eight depositional environments are populated with average petrophysical reservoir properties adopted from a North Sea field. These units are termed lithotypes here. Synthetic acoustic prestack seismic data are then generated with the help of an algorithm that includes all internal multiples and transmission effects. A nonlinear acoustic full-waveform inversion is then applied to the synthetic data, and two media parameters, compressibility (inversely related to the square of the compressional wave velocity v P ) and bulk density, r, are recovered at a resolution higher than the shortest wavelength in the data. This is possible because the inversion exploits the nonlinear nature of the relationship between the recorded data and the medium contrast properties. In conventional linear inversion, these details remain masked by the noise caused by the nonlinear effects A U T H O R SStefan Luthi is a professor in production geology and the head of the applied geology section at Delft University of Technology. He is also a senior technical advisor to Schlumberger Limited. Luthi holds a Ph.D. from the Swiss Federal Institute of Technology (ETH) in Zurich. During his career, he has worked on five continents and has published more than 50 articles in scientific journals. The results show that the eight lithotypes can be successfully recovered at a subseismic scale and with a low degree of processing artifacts. This technique can provide a useful basis for more accurate reservoir modeling and field development planning, allowing targeting of smaller reservoir units such as distributary channels and lower shoreface sands.

Reservoir Lithology Determination by Hidden Markov Random Fields Based on a Gaussian Mixture Model

“…The first example for applying the approach is the synthetic Book Cliffs model created by Feng et al [24] in which more details have been added and more differentiation is put on the potential reservoir lithologies than in the original [25]. As a test, only a subset of the whole 2-D section has been selected, and Fig.…”

Palynomorphs Content and Paleodepositional Environments of Mamu Formation in Okpekpe-1, Imiegba-1 and Imiegba-2, Benin Flank of Anambra Basin, Nigeria

“…The paleodepositional environment offers a basis for predicting comprehensive sedimentary characteristics, sand body geometry, and architecture of petroleum reservoirs. Formation outcrops are dependable analogs to subsurface lithofacies, and therefore, they are useful in studying facies distribution, reservoir characterization, and geohistory (Boggs, 2006;Tetyukhina et al, 2014). Palynomorphs are organicwalled microfossils with sizes that range from 5µm to 500µm, and they are generally composed of chitin, pseudochitin, sporopollenin and dinosporin.…”