Stratigraphic correlation of wells using discrete wavelet transform with fourier transform and multi-scale analysis

Abstract

Stratigraphic correlation of wells involves correlation of stratigraphic interfaces which should be continuous across the area between the wells. Stratigraphic correlation of wells comes at an advanced stage of reservoir estimation, where accurate quantitative information is required for prospect evaluation of the target reserve. It requires input from a variety of geophysical surveys ranging from seismic surveys to core analysis. In this work a novel and innovative technique using discrete wavelet transform with fourier transform and multi-scale analysis is demonstrated, which can be utilized for detecting stratigraphic interfaces and correlating them between wells. The technique was first tested on synthetic gamma ray logs for two synthesized wells and was then applied to the well data taken from geophysical surveys undertaken by dGB Earth Sciences in the Netherlands Offshore F3 Block. Discrete wavelet transform and fourier transform was applied to gamma ray logs to identify potential interfaces and then multi-scale analysis was used to characterize each horizon by finding its fractal dimension. Interfaces which had similar lithology and thickness, had similar fractal dimensions and were therefore correlated. This approach was also compared with conventional wavelet based techniques and was proved to be superior. The well correlation was also independently verified by identifying marker beds using seismic data in between the wells, and there was good agreement between the results that were obtained.