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Learnings from a Previous HitVerticalNext Hit Previous HitSeismicNext Hit Profiling (VSP) Programme

Saeed A. Al-Yarubi1*, Shadia F. Al-Farsi2, and Nasser T. Al-Touqi2
1Bristol University, UK
2Sultan Qaboos University, Oman
*[email protected]

Petroleum Development Oman (PDO) has been acquiring VSP (Previous HitverticalNext Hit Previous HitseismicNext Hit profile) data for the past 30 years. The different types of VSP data have been used for different objectives. ZOVSPs (zero-offset Previous HitverticalNext Hit Previous HitseismicNext Hit profile) and OVSPs (offset Previous HitverticalNext Hit Previous HitseismicNext Hit profile) are considered valuable and are used for time-to-depth calibration, Previous HitseismicNext Hit-to-well matching and identification of multiples on surface Previous HitseismicNext Hit. The OVSP is normally carried-out in deviated wells or over steeply dipping layers. We will show that the processing of ZOVSP and OVSP is not trivial and how erroneous processing steps or changing assumptions can lead to very different results. This will be demonstrated with a case study of processing ZOVSP with different contractors. WAWVSPs (walk away Previous HitverticalNext Hit Previous HitseismicNext Hit profile) have typically been used in an attempt to obtain better structural imaging and for time-lapse studies with limited or no successes. In PDO the confidence level in WAWVSPs is often low, resulting from an often-observed poor match of the processed WAVSP data with surface Previous HitseismicNext Hit data. This mismatch is observed in the form of: (1) considerable differences in structural dip; (2) events that could be interpreted as faults, which are not present in the surface Previous HitseismicNext Hit; and (3) wrong amplitudes differing from surface Previous HitseismicNext Hit. In addition to these problems, the bandwidth of the VSP data is not higher than surface Previous HitseismicTop, contrary to expectation. These problems will be illustrated with examples of processed WAWVSPs from different fields.


AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain