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Finding Fluid Conduits or Barriers through Seismic Fault Extraction—A Revolution in Sweet Spot and Compartment Mapping

Ralf Oppermann
OPPtimal Exploration & Development Pty Ltd

During the last two decades, volume interpretation techniques have increasingly revolutionised traditional 3D seismic interpretation workflows in the Oil and Gas industry. While traditional interpretation mainly relies on an interpreter to work through a large volume of data to identify and manually characterise subsurface geology and resources, volume interpretation allows to filter and classify subsurface features and extract 3-dimensional geological information through automated processes at a much faster pace, with higher accuracy and at higher resolution.

This talk presents results from the application of novel techniques in highest-resolution seismic fault extraction to various conventional and unconventional resources. The results challenge widespread perceptions of what is seismically resolvable from 3D seismic data, and offer groundbreaking new insights into the spatial distribution of fault and associated fracture networks and how they can affect the drilling, exploration and production of resources.

New Well Screening & Planning (WS&P) techniques, as well as Improved Resource Recovery (IRR) workflows will be presented that are focused on the full integration of new techniques in hi-res fault extraction with the detailed review of various geophysical, geological, geomechanical, drilling and production data.

Examples from various reservoirs around the world demonstrate the significant value that can be added when delineating 3-dimensional fault and associated fracture networks at high resolution and directly and quantitatively relating this information to drilling and production observations (Figure 1).

In most resource industries, it is critical to improve the understanding, detection, modelling and prediction of fault and fracture networks. The key problem for the development of fractured resources is the difficulty to visualise the exact location and geometry of fractures (Lonergan et al. 2007, Fractured Reservoirs, Geol Soc Spec Publ 270).

This is where novel techniques and workflows in Automated Fault Extraction offer new opportunities to visualize fault and associated fracture networks at extremely high resolution. The workflows provide a completely new basis for the reliable identification and quantifiable prediction of fault networks in the subsurface, and allow to reliably delineate larger and smallerscale faults and predict fluid pathways in the subsurface.

High-resolution fault extraction typically results in the recognition of many small-scale fault penetrations in wells. These fault penetrations are often directly linked with a number of drilling and production problems, or opportunities. Fault penetrations are often linked with drilling problems (e.g. fluid losses, borehole instability), as well as production issues (water production along fault planes, x-flow between wells) or production opportunities (access to productive natural fracture networks, 'sweet spots'). The new techniques can therefore provide a step-change in understanding drilling, safety and production issues in existing wells.

The new techniques can also be utilised to optimise future resource activities and recoveries from resources. Fluid barriers, fluid conduits or drilling hazards in the subsurface can be reliably predicted, which allows to reduce drilling risks and costs, locate sealing or open fault & fracture networks and significantly increase resource production from assets.

It will be demonstrated that a focused application of the new technology workflows delivers increased recoveries from resources, and also results in safer, cheaper and more successful drilling operations. The new techniques are proposed as Best Practice workflows for the exploration & development of both conventional and unconventional resources.

Figure 1. High-resolution fault extraction visualises smallscale spatial changes in amplitude, frequency or phase content of 3D seismic data, and challenges perceptions of what can and can not be identified with seismic data. Comparison and calibration of seismic fault extractions with faults identified in wells (from, e.g., core, image logs/dipmeter or log correlation) helps to ground-truth extractions and assess the true seismic fault resolution of a particular data set at objective level.

AAPG Search and Discovery Article #90179©2013 AAPG Geosciences Technology Workshop, Houston, Texas, August 6-7, 2013