کاربرد آنالیز طیفی در چینه‌نگاری سکانسی و تعیین چرخه‌های میلانکوویچ در سازند سروک در میدان کوپال

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه زمین‌شناسی، دانشکده علوم پایه، دانشگاه فردوسی مشهد

2 شرکت ملی مناطق نفت‌خیز جنوب، اداره عملیات زمین‌شناسی

چکیده

سازند سروک (آلبین تا تورونین) یکی از واحدهای کربناته در جنوب­غرب ایران است که در حاشیه نئوتتیس نهشته شده است. هدف از این مطالعه آنالیز چینه­نگاری سکانسی و شناسایی چرخه­های میلانکویچ این سازند در چاه­های شماره 20 و 48 میدان کوپال به روش آنالیز طیفی MESA و با استفاده از نرم­افزار سیکلولاگ و لاگ گاما است. مطالعه 250 نمونه میکروسکوپی منجر به شناسایی 9 میکروفاسیس شد که در سه محیط رسوبی دریای باز، سد و لاگون بر جای گذاشته شده­اند. علاوه بر این دو سکانس رسوبی رده سوم (بر اساس تغییرات رخساره­ای و نیز تغییرات منحنی­های PEFA و INPEFA) نیز شناسایی شده است. بررسی چرخه­های میلانکوویچ با استفاده از دو روش تعیین فواصل بین پیک­های گاما و آنالیز MESA نشان داد که غالب آن­ها از چرخه­های 100 هزار ساله تشکیل شده­اند. سن­سنجی مداری با توجه به شمارش این چرخه­ها نشان داد که این بخش از سازند که مورد حفاری قرار گرفته سنی معادل 11 تا 12 میلیون سال دارد.

کلیدواژه‌ها


عنوان مقاله [English]

Application of spectral analysis in sequence stratigraphy and Milancovich cycles identification in Sarvak Formation in Kupal Oilfield

نویسندگان [English]

  • F. Abasaghi 1
  • A. Mahboubi 1
  • S.R. Mousavi Harami 1
  • Sh Avarjani 2
چکیده [English]

The Sarvak Formation (Albian to Turonian) is one of the carbonate units in the southwest Iran that was deposited on Neotethys margin. The purpose of this study is to analysis sequence stratigraphy and to identify Milankovitch cyclesof this formation in wells No. 20 and 48 in the Kupal Oilfield. This study was done by MESA spectral analysis method, using Cyclolog software and gamma ray data. The study of 250 thin sections led to identification of 9 microfacies that were deposited in three depositional environments including lagoon, shoal and open marine. In additions two third order depositional sequences (based on facies variations and changes PEFA and INPEFA curves) were identified. Examination of Milankovitch cycles, using both interval variations between gamma ray peaks and MESA spectral analysis methods showed that most of them formed 100,000 years cycles type. Orbital age determination with respect to counting of these cycles showed that this part of drilled formation has 11 to12 million years age.

کلیدواژه‌ها [English]

  • Sarvak
  • gamma
  • MESA
  • Sequence Stratigraphy
  • Milankovitch cycles

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