Emil Lundberg

Reflection seismic investigations in the Dannemora area, central Sweden: Insights into the geometry of polyphase deformation zones and magnetite‐skarn deposits

The Bergslagen region is one of the most ore prospective districts in Sweden. Presented here are results from two nearly 25 km long reflection seismic profiles crossing this region in the Dannemora ...

High-resolution 3D reflection seismic investigation over a quick-clay landslide scar in southwest Sweden

Quick-clay landslides often occur in the northern hemisphere in areas that were covered by Pleistocene glaciation. They are particularly common along the shorelines of the Gota River in southwester ...

Reducing the risk of hydrocarbon exploration and lithology characterization — using a neural network approach in the West Delta Deep Marine Concession Area, Offshore Nile Delta, Egypt

There are many approaches and concepts for the exploration and development of hydrocarbon reservoirs. In this study, we develop both a lithology classification and a gas chimney prediction workflow. We classify the entire seismic volume into its most likely facies domains and transform the seismic cube into a gas chimney probability cube. Both these approaches utilize a neural network algorithm, which we find is an efficient method to integrate the multiple input attributes required to extract the target log, or to isolate target features from the seismic background data. A combination of a set of seismic attributes (obtained from multilinear regression) with the nonlinearity of the artificial neural network technique is used to develop effective workflows to classify and explore the reservoirs. Analysis of the results helps to quantify the chance of success of the exploration prospects and also, in conjunction with the petroleum system of the prospects, leads to a reduced risk of the hydrocarbon exploration and development wells.It is estimated that urban life will be the norm for around 60% of the world’s population by 2040, leading to a more centralized distribution of people and making the city as the main place of resi ...

Seismic and Electrical Resistivity Investigations for the Planning of a Tunnel in Oslo Outskirts

Oslo municipality is presently planning bus and car tunnels to facilitate its accessibility and increase traffic efficiency. Urban environment is usually a challenge for geophysical pre-investigations because of the various sources of noise, vibrations and restriction both in time and space. These technical challenges were overcome with the use of a newly developed seismic streamer specifically designed for noisy urban areas, from an industry-academia partnership. A total of 3.5 km long seismic data along 14 profiles were acquired for the tunnels pre-investigation with the main goals of (1) obtaining information about depth to bedrock, (2) detecting potential weakness zones, and (3) optimizing the number of drillings and their locations for a follow-up study. In addition, six electrical resistivity tomography profiles were acquired near the planned tunnel alignments. Inversion of first breaks and electrical resistivity data provides a seamless depth to bedrock interface that is in most places in good agreement with the nearby geotechnical soundings. In addition, the geophysical sections reveal the bedrock undulation character and provide some indication of weakness zones. This case study also illustrates that if the pre-investigation had been based only on boreholes, it would have overseen a potential difficulty during excavation.

High-resolution Reflection Imaging for the Planning of a Double Train-track Tunnel in the City of Varberg, Sweden

A newly developed broadband MEMs-based seismic landstreamer system was employed for the planning of a double train-track tunnel in the city of Varberg, southwest Sweden. In addition to the refraction analysis and velocity tomographic modeling, reflection processing of the data was considered given the good quality of the data and realization of reflections in some raw shot gathers. Bedrock is strongly reflective in most cases and only at occasions when reaches near the surface it disappears in the reflection section. Bedrock undulation is clearly noticeable in most reflection sections and at one occasion it appears to be strongly diffractive. The diffraction signature is now known to be associated with a buried water tank used in fire emergency situations. Reflection seismic data greatly complements tomographic models and may support a deep bedrock at where the tunnel is planned to be excavated in the downtown Varberg.

Cross-correlation Time-lapse Static Corrections Versus Refraction Static Corrections on 4D Land Seismic CO2 Monitoring

Difficulties encountered during the processing of the timelapse 3D land-seismic data at the CO2 geological storage site at Ketzin, Germany, were to a large extent attributed to changes in near-surface velocities. Two workflows for processing of the 4D data were tested. The first one included re-calculation of the refraction static corrections based on new information about the near-surface from first breaks. This workflow showed that the near-surface changes could only imperfectly be resolved by new refraction static corrections. The second workflow included cross-correlation of the traces acquired at the same locations but during different campaigns and calculation of the prestack time shifts between the surveys. Both workflows demonstrated their capability to minimize the time-lapse noise and enhance the time-lapse reservoir signature. They provide similar time-lapse results, except that the cross-correlation workflow is quicker, more accurate and displays less time-lapse noise.