IDENTIFCATION OF HIGH VELOCITY ANOMALIES, IMPERCEPTIBLE TO SEISMIC RESOLUTION, BY INTEGRATION OF SEISMIC ATTRIBUTES, IN 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; Wyandot formation; Naskapi member; seismic attributes; seizmička anomalija brzina; formacija Wyandot; član Missisauga; član Naskapi; seizmički atributi; Canada; naskapi
• Online Access: https://hrcak.srce.hr/216280; https://hrcak.srce.hr/file/315596

Penobscot Field is located in the Sable Sub-basin, in the Nova Scotia Basin, belonging to the Canadian territory, and for the year of 1991, a 3D seismic acquisition was carried out in this region. Also, two exploratory wells were previously drilled (L-30 and B-41). Then, with the subsequent interpretation of the area, a discrepancy was found around 10ms to 15ms (approximately 25m) in the travel times of the seismic waves in the vicinity of well B-41, resulting in a false structural high in the Mississauga Formation and Naskapi Member. It is possibly caused by changes in geological facies and thickness of the Wyandot formation, consequently, B-41 well became dry. For these reasons, to identify the possible problem which caused everything mentioned above, the area between the wells was delimited by a seismic subvolume (by reducing the seismic cube), making a seismic interpretation of the top of the formations of interest, as well as an analysis of certain petrophysical properties in the wells, in order to delimit the thickness of the anomaly and, consecutively, the use of the seismic attributes for lateral identification of the anomaly in the Wyandot Formation. Polje Penobscot nalazi se u podnožju Sable, u bazenu Nova Škotska koji pripada kanadskomu području, gdje je 1991. godine načinjeno 3D seizmičko snimanje. Prethodno su izbušene dvije istraživačke bušotine (L-30 i B-41). Zatim je, uz dodatnu interpretaciju, otkriveno vrijeme prolaska 10 do 15 ms (otprilike 25 metara) seizmičkih valova u blizini bušotina B-41, što je rezultiralo interpretacijom „lažnih” struktura unutar «lanova Missisauga i Naskapi. To je vjerojatno uzrokovano promjenama u sastavu i debljini Wyandotove formacije. Prepoznavanje uzroka lažnih signala bušotina B-41 dobro je izvedeno. Prepoznavanjem lažnih ocrta bilo je moguće područje između dviju spomenutih bušotina ocrtati kao seizmički podvolumen, odnosno kao dio „seizmičke kocke”. Time je seizmička interpretacija postala strukturno ispravna, uz dodatno omogućavanje analize određenih petrofizičkih svojstava u bušotinama. Nadalje, utvrđena je debljina područja „anomalnoga” odziva, kako po okomici tako i bočno, a unutar formacije Wyandot.