Why Pre- Stack Data? by Kristian Kolbjørnsen (DNO) and Arild Haugen (NPD) FORCE seminar 6.2.2002

Pre-Stack Data Introduction History Logistics Processing Applications Actions/Suggestions

Introduction Seismoscope (132 ad) Newton Hilbert/Gödel Infomation/Exfomation: crucial for all communication ??..?

Les Miserables ?

Les Miserables !

History Analog period < 1960+; Pre-stack only! CDP concept ~ 1960’ies Digital technology >1960 Increased density in time and space 3D ~ 1980 Sophisticated processing Wave eq. Mig, ~ 1980

To pile something in a (conical) heap. Ethymology: Stack Stack, from Old-Norwegian stakkr stak stakk (Swedish: stack) To pile something in a (conical) heap. Stakk Høystakk Rifle Stack Stakkitt KongeStakk Kortstokk

Usage of Pre-Stack Data Examples: Data enhancements (Statics, filtering, CDP stack etc ) Velocity analysis: Taner and Koeler (1969) - ProMax (1985)  Today; same basic technology GSI 700 package!

What’s lost? Stacked data loaded toWorkstations 1:1000 (4 ms, 25m, 60 fold, 8 bit) Are we paying for more than we use? Refractions Reflections Noise Shot from the Paris Basin

What is hidden? Something MUST be hidden or at worst lost

How much info can we receive? Info received through eye: 10 Mbps Human brain extracts only 14 bps (Nørretranders, 1993) Age 50 100 Age

What can be revealed? Zi, Vp, Vs ….. λ μ ρ p , Φ , So, Sw… λ μ ρ p , Φ , So, Sw…                                             Aroma, Bouquet, Taste…. Stringent høye bærtoner

Post-Stack State-of-the-art Modern visualisation of post stack data a major step in the right direction New Paradigm Colour and motion assist the human brain in recognising patterns by rapid scans through the 3D cube However: Only the creative and experienced interpreter will be able to find Zen in the art of interpretation Geoprobe/Magic Earth

Data power For planning the future ALWAYS keep in mind the IT development curve There are no signs that this will change

1:1000 99,9 % of the data represents a potential

Accessing pre-stack data Lost time: 4-8 weeks Costs: Expensive reprocessing Expensive copying Example from DNO2002:

Philosophy Properly stored and easy access Standard formats (i.e.SEGY) Indexed Edited only (traceable) ”Standard” processing sequence (traceable) =>PETROBANK Appellation d’Origine Controlee French wine-standards

Reasons not to store pre-stack data? Cost? Cumbersome? Conservativism? Contractor opposition? Complete waste? Ignorance? Politics? Strategy? Cooperation is for communists!

Reasons to store Pre-stack data in Petrobank IT price-performance development (Rio) Prestack only 100 x poststack Proper storing costs only a fraction of acquisition costs Access Prevent data media degradation Backup Data cleaning and QC Time is money….

Storing Pre-stack data Data volume not an issue NPD can regulate the treatment of pre-stack data along the same guidelines as post-stack: For this afternoons discussion: Define pre-stack data as a part of the National Dataset

The search for Zp, Vp and Vs Topics: Wave Equation vs Ray Based (EAGE workshop) Kirchhoff becoming state-of-the art (Clustered Linux/PCs) Transverse Isotropic media with a Vertical axis of symmetri (VTI) – Leon Thomson Angle Stack/Migration Full Elastic Inversion vs Near/Far stack inversion AVO Clustering Velocities Workstations/Visualisation

Summary and key factors for success Easy access Visualisation Applications User interface Availability will stimulate many new ideas! The Pre-Stack era has just started

Thank you!

Proposal FORCE to initiate a project/work group Members: Authorities, Oil Companies and Contractors Mandate: Refine/Extract ideas from the seminar If necessary define pilot project(s) Propose an action plan for the treatment of PSD Discuss with NPD and OLF’s and FORCE’s seismic work groups