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North American Case Study Demonstrates the Ability of 3-D/3-C Seismic Data to Predict the Petrophysical Properties of Shale

Harris, Ron E.1; Tinnin, John 2
(1)Anadarko Petroleum, The Woodlands, TX. (2) GX Technology, Houston, TX.

The Devonian age Marcellus is a major shale play in North America that has drawn international attention. Commerciality was established in 2004 and the basin now has well over 100 rigs actively drilling. The majority of these wells are drilled as horizontal wells with laterals 1 to 2 kilometers in length. Hydraulic fracturing is used to stimulate a sufficient volume of shale that will produce commercial quantities of natural gas. Within the study area, the Marcellus Shale is approximately 60 meters thick and buried at a depth of 2.6 kilometers.

The challenges of this play include:

1)identifying shale ‘sweet spots’ which represent areas of higher productivity that are driven by several petrophysical properties including porosity, permeability, brittleness and total organic content (TOC);

2)optimizing well designs and geo-steering through detailed, seismically derived structure maps that identify subsurface features such as fold axis, faulting and collapse associated with salt dissolution;

3)optimizing the stimulation program by understanding the variances in rock properties within the shale zone and the areal distribution of Young’s Modulus, Poisson’s Ratio, and local stress regimes.

To address these challenges, a 67 square-kilometer, wide-azimuth, multi-component Previous Hit3-DNext Hit seismic survey was recorded in central Pennsylvania to determine the effectiveness of modern 3-D/3-C seismic data in extracting certain rock properties from the Marcellus Shale.

A rock physics study was conducted on well logs penetrating the “Shale” within the survey area to model the predicted seismic attribute response. Analysis of the modeled attributes provided valuable insight into shale porosity, brittleness, kerogen content, VP/VS and density. Seismic attribute volumes that reflect elastic properties were generated from the seismic data along with geometric attributes of curvature and Previous HitcoherencyNext Hit. Multiple Previous HitinversionNext Hit techniques were investigated, including a P-wave simultaneous Previous HitinversionNext Hit and a joint PP/PS Previous HitinversionNext Hit to document the value derived from the 3-D/3-C seismic data. All elastic and geometric seismic attribute volumes were calibrated to the existing subsurface data including wireline, core, microseismic and production information. By utilizing these multiple attribute volumes and Previous HitinversionTop products, ‘sweet spots’ can be identified to optimize drilling locations and stimulation programs.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.