نشریه علوم زمین خوارزمی

نشریه علوم زمین خوارزمی

ارزیابی ژئوشیمیایی و بررسی پتانسیل هیدروکربن زایی سازند گرو در میدان جفیر منطقه دشت آبادان، جنوب غرب ایران

نویسندگان
مژده انصاری 1
مرتضی آسمانی 2
بهزاد مهرابی 1
بیوک قربانی 3
1 دانشگاه خوارزمی
2 دانشگاه خوارزمِی
3 پژوهشگاه صنعت نفت
10.22034/KJES.2024.10.2.106672
چکیده
دشت آبادان واقع در جنوب غربی ایران به ‌عنوان یکی از غنی‌ترین حوضه‌های نفتی کشور و بخشی از حوضه عظیم بین‌النهرین شناخته می‌شود. کشف منابع جدید هیدروکربنی در این منطقه در سال‌های اخیر و وجود میدان‌های مشترک، بیانگر ضرورت انجام مطالعات گسترده زمین‌شناسی و ژئوشیمیایی در این منطقه است. علی‎‌رغم اهمیت سازند گرو به عنوان یکی از سنگ‌های منشأ کلیدی در این منطقه، تا کنون مطالعه دقیقی به منظور بررسی پتانسیل ‌هیدروکربن‌زایی این سازند در میدان جفیر انجام نشده است. در این مقاله، ارزیابی ژئوشیمیایی سازند گرو به عنوان سنگ منشأ احتمالی در شمال دشت آبادان در میدان جفیر مورد بررسی قرار گرفت. بدین منظور تعداد 14 نمونه خرده حفاری از سازند مذکور برای ارزیابی کمیت، کیفیت و بلوغ مواد آلی در این سازند به روش آنالیز پیرولیز راک-اول مطالعه شد. نتایج آنالیزها نشان داد که سازند گرو با میانگین کربن آلی 2/2 درصد وزنی و شاخص هیدروژن متوسط برابر mg HC/g TOC 303 عمدتا از نوع مواد آلی دریایی (کروژن تیپ II) بوده و کمی مواد آلی خشکی (III) نیز به همراه دارد. بنابراین سازند گرو به عنوان یک سنگ منشأ با پتانسیل خوب تا عالی در میدان جفیر شناخته می‌شود. همچنین بلوغ حرارتی سازند گرو بطور متوسط معادل انعکاس ویترینایت حدود 8/ درصد است که بیانگر پیک پنجره نفتی می‌باشد. میزان اثر ماتریکس و موادآلی خنثی در سازند گرو، از طریق ترسیم نمودار S2 در برابر TOC و رسم خط رگرسیون آن نیز بررسی شد. نتایج نشان می‌دهد که مقدار قابل توجهی از هیدروکربن تولیدی به‌ میزان mg HC/g TOC 2/5 توسط ماتریکس جذب می‌گردد که نقش ماتریکس معدنی را در تحلیل‌های ژئوشیمیایی این سازند برجسته می‌کند. این مطالعه نشان داد که سازند گرو می‌تواند نقش مهمی در شارژ سازندهای مخزنی بالاتر در میدان جفیر داشته است.

کلیدواژه‌ها
پیرولیز راک-اول
پتانسیل هیدروکربن‌زایی
سنگ منشأ
اثر ماتریکس معدنی
میدان جفیر

عنوان مقاله English

Geochemical evaluation and hydrocarbon potential of the Garau Formation in the Jufair field in Abadan Plain, SW Iran

نویسندگان English

Mozhde Ansari 1
Morteza Asemani 2
Behzad Mehrabi 1
Buyuk Ghorbani 3
1 Kharazmi University
2 Kharazmi University
3 Research Institute of Petroleum Industry (RIPI)
چکیده English

The Abadan Plain is one of the most prolific basins in southwestern Iran and a part of the Mesopotamian Basin. In recent years, exploring new hydrocarbon resources in the region and the occurrence of shared oil fields in this region necessitates comprehensive geological and geochemical evaluations. Despite the significance of the Garau Formation as a key source rock in this region, no detailed study has yet been conducted to evaluate its hydrocarbon generation potential in the Jufair field. This study investigated the geochemical evaluation of the Garau Formation as a candidate source rock in the Jufair oil field in northern Abadan Plain. For this purpose, Rock-Eval pyrolysis analysis was conducted on 14 cutting samples to assess the quantity, quality, and thermal maturity of organic matter. The results indicated that the Garau Formation has an average total organic carbon (TOC) content of 2.2 wt.% and an average hydrogen index (HI) of 303 mg HC/g TOC, which is dominantly composed of mostly marine-type organic matter (i.e., Type II kerogen) with slightly terrestrial organic matter (i.e., Type III kerogen). Hence, the Garau Formation was classified as a good to excellent source rock in the Jufair oilfield. Also, the average thermal maturity of the Garau Formation is equal to the vitrinite reflectance of 0.8%, which implies the peak of the oil window. The matrix effect and inert organic carbon in the Garau Formation were also examined by plotting S2 versus TOC and drawing a regression line. The results showed that the matrix can absorb a significant amount of generated hydrocarbons, equal to 2.5 mg HC/g Rock, highlighting the mineral matrix has an essential role in the geochemical nature of the formation. This study emphasizes that the Garau Formation has played a vital role in charging the overlying reservoir formations in the Jufair oil field.

کلیدواژه‌ها English

Rock-Eval pyrolysis
Hydrocarbon potential
Source rock
Mineral matrix effect
Jufair oil field
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