The use of existing geological and structural maps, previous 2D seismic profiles, boreholes and correlation models between these data is sufficient to understand basin structure and thermal systems on a regional scale. However, this is not sufficient on a scale of a geothermal site....
Reflection-based full waveform inversion (RFWI) is increasingly used to recover long wavelengths of the background velocity model and provide updates that extend beyond the reach of diving waves. In our case study, we use an RFWI method that first updates the density using the high-wavenumber components of the decomposed full waveform inversion (FWI) gradient and then updates the velocity using the low-wavenumber components. We show on a deep water example from the Mexican side of the Perdido fold belt that RFWI improves the velocity inside the sediment mini-basins and thus the interpretability of the underlying salt. We also apply this method for the intra-salt and subsalt velocity updates and show how it can improve imaging of the deep targets.
In this paper, we focus on how to use PS imaging to help detecting the reservoir in the clastic layers. PS data allows for imaging of these reservoir units that have poor P-wave but high PS-wave reflectivity and also for lithological discrimination via extracted Vp/Vs values. To achieve such information, there are some key processing steps necessary to resolve. These include shear wave inversion, shear wave splitting analyses, demultiple, and finally, PP-PS joint inversion. Also, the initial results of PP-PS joint AVO inversion shows clear indications of the alternative target zones, and conform to the interpretations of these pay zones.
A 24-well pad is auto-planned and shows the Separation Rule anti-collision display computed for all wells all at once. The color controls represent three collision risk categories: green = minimum risk, yellow = medium risk and red = stop drilling, maximum risk zones. (Source: CGG GeoSoftware)
HOUSTON–Cuttings are a valuable and cost-effective source of subsurface data from both vertical and lateral wells that is commonly overlooked in oil and gas exploration and development drilling. Advancements in analytical technologies have enhanced the data extraction from cuttings to provide key subsurface insights, in lieu of core or sidewall core data.
Exploration in the Northern North Sea has been extremely successful, with important discoveries such as Statfjord in 1974, and Oseberg, Snorre, Gullfaks and Troll, discovered in 1979. More recently, several smaller but still very valuable discoveries have been made, demonstrating the remaining potential of the area.
Over the past 35 years, geothermal projects have been developed in the Upper Rhine Graben (URG) to exploit deep geothermal energy. Underneath approximately 2 km of sedimentary deposits, the deep target consists of a granitic basement, which is highly fractured and hydrothermally altered. Therefore, it has high potential as a geothermal reservoir.
Deterministic seismic inversion methods have been successfully used in many exploration and production projects in the petroleum industry. Some of the benefits of these methods are: the inverted impedances are rock properties tightly calibrated with well data; the seismic inversion process itself attenuates the wavelet effects, reduces side-lobes and tuning effects and enables quantitative predictions of reservoir properties, all of which are advantages to improving the understanding of the reservoir geology and better management of the drilling programs. However, when the reservoir is below the resolution of the seismic and/or has thinner low permeability barrier layers (compartments), estimating the reservoir volume and/or evaluating the connectivity in the reservoir geobodies from deterministic seismic inversion become less accurate and in many cases unfeasible. In such cases, the geostatistical seismic inversion method provides more accurate reservoir volumes and the uncertainty associated with the 3D models can be assessed and quantified. For the work described in this paper, we used a stochastic inversion methodology, which simulates many possible scenarios, to better discriminate the thickness of the sand/shale layers and the areal extent the layers in the Oligocene reservoir in the Barracuda Field, Campos Basin, offshore Brazil.
It is often observed that common image gathers computed after FWI are not flat. This is due to an improper anisotropy estimation. We propose a new joint reflections-diving rays tomography to estimate anisotropy prior to FWI. It aims at both flattening the common image point gathers and matching the kinematics of the observed and synthetic diving waves. The method is successfully demonstrated on a real land 3D broadband dataset.