Value Addition by Walkaway VSP, Offshore India

Nidhi Jindal, Prativadi Jyothi, Sanjay Tiwari, Ajoy Biswal, Pranaya Sangvai, and Ravi Bastia
G&G, Reliance Industries Limited, Navi Mumbai, India

Walkaway VSP data plays a major role in reservoir delineation and characterization. Present study is from a prospect in the deep water of Krishna-Godavari basin. The basin is underlain by a series of NE SW trending en-echelon horsts and grabens. As such well path was not predicted to intersect any major fault plane, but there were some possibilities of intersecting small scale unknown fault planes at reservoir level. Walkaway VSP has been taken as a possible supplementary solution to delineate the small scale faults close to well, and to understand compartmentalization and fluid continuity within the zone of interest. Objectives for WVSP were
(1)Delineation of reservoir extent with improved
S/N ratio compared to Seismic.
(2)Increased Resolution of reservoir zone
(3)Correlation of zero offset VSP, seismic and WVSP.
(4)Estimation of AVO effect
(5)Anisotropy Estimation
(6)Delineation of fault/sub-seismic-fault close to well.
WVSP has been designed keeping above objectives into consideration. The image result presented in this paper shows, how walkaway VSP is able to evaluate our objectives using high-end processing techniques, VSFusion Vector 3D Migration and VSFusion MultiViewSM. The paper demonstrates how a walkaway VSP data can be processed in a true amplitude manner to obtain a high resolution image, which provides better imaging of reservoir sand. The addition by WVSP is seen by way of estimating anisotropy and avo effect. The value addition by WVSP helps to position the appraisal wells more accurately and reduce the risk of dry wells.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery