Introduction
In 2013 SGS Horizon, in combination with Z-Terra and Moser Geophysical Services, carried out a reprocessing job for operator Oranje Nassau Energie which involved the merger of the surveys Q16 and Monster. The pre-processing of the data was followed first by a pre-stack time migration and then a pre-stack depth migration. Pre-processing and subsequent pre-stack time- and depth-migration were amplitude preserved since the reservoirs are fluid sensitive. Velocity analysis during the PSDM phase was performed by tomography where three levels were considered: pre-Chalk, Chalk and post-Chalk. Depth migration was performed in anisotropic mode. The availability of a high-quality migration velocity and focusing of the depth image provided optimal conditions for subsequent diffraction imaging and deployment of diffraction imaging technology in the North Sea.  

Q16
The working area is in the licences Q16a and Q16bc in the southern part of the Dutch North Sea (Figure 1).

Figure 1 Location of Q16 in the Dutch offshore

The primary target in the area comprises the Main Buntsandstein of the Q16A and Q16- Maas fields including their near-field exploration prospects. The depth range of this target is approximately from 1500–4000m. In addition, the Lower Cretaceous Vlieland Formation represents a secondary target. No sub-salt imaging is required as no movable Zechstein salt is present in subject area. The structural setting is defined by two key tectonic features: pre-Cretaceous block faulting (mainly caused by Jurassic rifting of the West Netherlands Basin) and Late Cretaceous to Early Tertiary basin inversion. The compressional inversion is relative mild in the Q16 area at the southwestern edge of the West Netherlands Basin.    Continue Reading →

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Introduction
In 200 shale gas represented just 1% of American natural gas supplies. Today, it is 30% and the percentage keeps increasing. The technology to drill and fracture shale formations is now exported from the US to the rest of the world, increasing national oil and gas reserves in many other countries. Currently, there is a high level of activity for both shale gas and liquids production. Productivity in the shale plays depends on many factors including total organic content, the susceptibility of the reservoir to hydraulic fracturing and factors in the well design and completion processes.

Figure 1 Cross section of Middle to Late Cretaceous rocks of south-central Texas.The Eagle Ford Formation pinches out to the northeast over the San Mancos Arch. (After Hentz and Ruppel, 2010).

However, since reservoir porosity is exclusively fracture porosity, the detection of naturally occurring faults and fractures and the interaction of these with the hydraulic
fracturing process are key areas of investigation.    Continue Reading →

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HOUSTON–In 2000, shale gas represented only 1 percent of U.S. natural gas supplies. Today, it is 30 percent and that percentage keeps increasing. The technology to drill and fracture shale formations
is being exported to the rest of the world, increasing national oil and gas reserves in many other countries.

The thickness of shale formations is often only a few hundred feet, so new, high-resolution echnologies are needed to visualize the structure and the natural fracture distribution and orientation in these thin shale layers. High-resolution imaging of small-scale fractures in shale reservoirs has the potential to improve production and recovery efficiency, reduce field development costs, and decrease the environmental impact of developing the field by using fewer wells to optimally produce the reservoir.

Diffraction imaging (DI) is a novel technology that uses diffractions to image with super-resolution small subsurface elements that produce diffractions such as small-scale faults and fractures. Since diffractors are, by definition, smaller than the wavelength of seismic waves, diffraction imaging provides super-resolution information, which consists of image details that are beyond the classical Rayleigh limit (the minimum resolvable detail) of half a seismic wavelength.

FIGURE 1A. Specular Reflection and Diffraction Imaging Comparison

FIGURE 1B. Resolution of Kirchhoff Migration (left) versus Diffraction Imaging (right)

Diffraction imaging can be used to complement the structural images produced by conventional processing by generating an additional image volume of high-resolution unconformities. By identifying the areas with increased natural fracture density, reservoir engineers can design an optimal well placement program that targets the sweet spots and areas with increased production, while minimizing the total number of wells used for a prospective area.   Continue Reading →

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