Application of High-Resolution Seismic Investigation for Geohazard and Geotechnical Assessment in Deepwater Field Developments

J. L. Gibson, R. C. Shipp, J. S. Smith, and J. A. Newlin
Shell International E&P, Inc, Houston, TX

Deepwater settings present a challenging environment for planning and executing field developments. The combination of complex geology and expensive drilling and development scenarios requires early assessment of the geohazard and geotechnical issues for evaluation of development feasibility, as input to economic models and to guide the planning and execution of high-resolution site surveys and geotechnical data collection.

To address this challenge, the approach used by Shell the past few years has been to maximize the utility of existing 3D seismic data through high-resolution reprocessing, and to characterize the seabed and the shallow subsurface geology through focused “desktop studies.” Assessment of regional-scale issues, for example, export pipeline route feasibility, to field-scale components, such as preliminary drilling sites and flowline layouts, are thereby addressed early in the project. More expensive site survey data is acquired at a suitable time in the project, only when needed, and in a targeted and cost effective manner. However, in cases where high-resolution site survey data has been acquired (i.e. short-cable high-resolution 3D seismic data, deep tow and AUV surveys), the order of magnitude increase in resolution often reveals important geohazards, particularly at the seabed, which prove to be critical in the field development plan. The combination of site survey data and reprocessed 3D seismic data results in a geohazards interpretation which is robust, and which provides a solid basis for progressing the field development plan in the most time efficient and cost effective manner.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005