Schlumberger

Technical Paper: Dip or Strike? – Complementing Geophysical Sampling Requirements and Acquisition Efficiency

Society: SEG
Paper Number: 5900296
Presentation Date: 2015
 

Abstract

Dip or strike? The shooting direction during the planning process for a new marine towed streamer seismic survey, depends on many factors. These factors include structural dip, fault orientation, survey dimension and the location of the survey area relative to no-access zones such as marine parks, international boundaries etc. Generally, the data is acquired in the dip direction to enable finer inline sampling in the dominant dip direction and perpendicular to the faults. However, in many cases economic factors override the geophysical issues and a survey is acquired in the most efficient direction. The case study presented here pertains to an area adjacent to a no-access zone, and the structural dip of interest is not aligned to the most efficient survey direction. Extensive 3D kinematic ray tracing analysis and 3D illumination studies were performed to estimate the illumination and sampling requirement for the steeply dipping fault zone. The need for optimal sampling in dip direction whilst maintaining efficiency led to data acquisition using multi-measurement streamers. This technology allows for reconstruction of the wavefield sampled equally in both inline and crossline directions, thereby achieving both operational efficiency and geophysical sampling requirement. To validate the integrity of the shooting direction decision, a swath of data was also acquired in dip direction and compared to the reconstructed data acquired in strike direction.

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