SOLUTION OF HIGH VELOCITY ANOMALIES IMPERCEPTIBLE TO SEISMIC RESOLUTION, BY MEANS OF SYNTHETIC MODELS, PENOBSCOT FIELD, CANADA

• Published in: Rudarsko-geološko-naftni zbornik
• Main Authors: García Moreno, Wilmer Emilio, Omaña Galeano, Iván Daniel
• Format: Article in Journal/Newspaper
• Language: English
• Published: Faculty of Mining, Geology and Petroleum Engineering University of Zagreb 2019
• Subjects: high velocity anomaly; Mississauga formation; Nova Scotia; Canada; lower and upper cretaceous; ray tracing; Kirchhoff PSTM and PSDM; visoka brzina anomalija; formacija Missisauge; Nova Škotska; Kanada; donji i gornji kredni; Ray-Tracing; Kirchhoff PSTM i PSDM; naskapi
• Online Access: https://hrcak.srce.hr/216285; https://hrcak.srce.hr/file/315606

Penobscot Field is located in the Sable Sub-basin in Nova Scotia, Canada, where a 3D seismic acquisition campaign was carried out in 1991 and also two oil wells were previously drilled (L-30 and B-41). In the interpreted seismic data, a discrepancy was found in the travel times of the seismic waves near well B-41, causing a false structural height in the Naskapi Member, Mississauga Formation (Early Cretaceous or Lower Cretaceous) and deeper formations (10 to 15 ms, i.e. approximately 25 m). It was decided to find a solution of this problem using synthetic models. First, making a delimitation of the study area by means of a seismic subcube, which were later interpreted surfaces of interest, through the well data. The average velocity and density properties were found for each interpreted strata. Subsequently, a 2D seismic acquisition was simulated, choosing a line that crossed both wells and through the use of ray traces, synthetic shot gathers were obtained and processed through the use of different seismic migration tests, and the final solution was found to be Kirchhoff pre-stacking migration in depth. Polje Penobscot nalazi se u subbazenu Sable u Novoj Škotskoj, Kanada. Tamo je 1991. načinjeno 3D seizmičko snimanje te su izbušene dvije naftne bušotine (L-30 i B-41). U interpretiranim seizmičkim podatcima uočeno je odstupanje u očekivanim seizmičkim brzinama u okolici bušotine B-41. Tako je ocrtano lažno strukturno uzdignuće unutar člana Naskapi (formacija Missisauge) i dublje (anomalija od 10 do 15 ms ili približno 25 m). Odlučeno je taj problem riješiti uporabom sintetičkih modela. Prvo su određeni volumeni seizmičke kocke, zatim površine za analizu te su uporabom bušotinskih podataka izračunane prosječne brzine i gustoća za svaki interpretirani sloj. Nakon toga je načinjen 2D seizmički model, koji je obuhvatio obje bušotine, praćenje sintetskih oblika, te Kirchhoffovu preseizmičku i postseizmičku dubinsku migraciju.