The Early Cretaceous sands on the Måløy slope constitute as reservoir for many oil and gas discoveries as seen in the Duva field and Hamlet and Ofelia discoveries. These sands have been deposited in submarine channels and fans, fed by material derived from the Norwegian mainland, through a series of shelf-edge canyons, established in the Late Jurassic.
We present a method to enhance the bandwidth of seismic data in the continuous wavelet transform (CWT) domain. By utilizing the features of CWT in detecting time-variant frequency content and automatically designing band-dependent time window, we can enhance the seismic bandwidth mostly based on signal. A high-dimensional implementation of the method enables us to make full use of the information from nearby data to stabilize the algorithm. A real data example shows that applying the proposed method at different processing stages has different benefits. If implemented properly, the approach is AVO friendly and a better alternative to conventional spectrum balancing.
Full-waveform inversion (FWI) uses the full wavefield as input but, in general, diving waves are the key driver of the method. How to maximize the contribution of reflected waves is an important factor for success of FWI, especially on seismic data with a short offset coverage. We propose Dynamic Resolution Time-Lag FWI (DR-TLFWI) to better utilize the reflections, especially for low-wavenumber velocity updates for better kinematics.
We present a means to estimate porosity and permeability at cm-scale resolution using whole-core computed tomography (CT) scans. We focus on carbonate reservoir intervals of the Buah Formation and Khufai Formation, both part of the Precambrian Nafun Group, from two wells located onshore Oman. We segmented the CT volumes and measured a range of vug properties such as size and shape descriptors, followed by multiple linear regression for all possible permutations of terms for the prediction of CCA porosity and permeability.
Marine vibrator sources offer the ability to emit a fully customisable and accurately repeatable sweep signature. Resulting peak amplitude levels are much lower than for airguns, making marine vibrators potentially preferable for the welfare of marine life. While the highly repeatable nature of the signal may be attractive for time-lapse applications, it must be considered alongside other time-lapse repeatability factors such as source positioning.
We present the use of elastic full waveform inversion (FWI) of surface waves to create a detailed shear velocity model of the near surface in the Middle East, where the shallow geology features strong velocity contrasts, making traditional velocity model building techniques challenging. The approach uses low-frequency virtual data from 3D interferometry and active surface waves to update the shear velocity model, providing valuable information for velocity model building and imaging. The study demonstrates the effectiveness of elastic FWI by comparing the results with the legacy velocity model and migrated images, showing improved resolution of the subsurface and simplified geological structures.
Land FWI has been applied to seismic data in the Sultanate of Oman in the past years, but its usage has been limited to low frequency updates and input for migration purpose only. With proper input data conditioning, initial model preparation and velocity inversion, we have managed to run acoustic FWI to 35 Hz. An FWI Image was then derived from the velocity, producing a superior image of the complex fault system compared to the conventional methods due to the utilization of the full wavefield and the least square fitting from low to high frequencies.
A multi-disciplinary project is presented utilizing data from the CGG archives and re-purposing them for porphyry copper deposit exploration. we reprocess the data, interpret and combine the results and place them within a holistic mineral systems framework to derive new exploration insights and demonstrate an effective methodology for search-space elimination and targeting.
The shallow water region of the Gulf of Mexico is known to present significant petroleum prospects due to dynamic tectonic activities during the late Cretaceous to early Tertiary. Previous imaging in this region using sparse ocean bottom cable (OBC) surveys was poor, mainly due to unresolved overburden velocity in the Mesozoic section. We implemented a velocity model building (VMB) approach driven by Time-lag full-waveform inversion (TLFWI) to resolve the complex velocity features in this area.