常磐沖前弧堆積盆地における白亜系海成泥質岩の石油根源岩能力
スポンサーリンク
概要
- 論文の詳細を見る
Gas and condensate have been discovered in the offshore Joban fore-arc Basin. They derived from coal and coaly mudstone in the Upper Cretaceous to the Miocene sediments. Although thick Cretaceous marine argillaceous rocks deposited in the basin, especially in the east of the Abukuma Ridge, they have not been evaluated as an effective source rock. Therefore, organic geochemical characteristics and petroleum generation potential were studied for the Cretaceous argillaceous rocks in the basin.The argillaceous rock samples from the MITI Joban-oki, MITI Kesennuma-oki, and Kita-Ibaraki-oki TJ-1 wells and from outcrops of the Futaba and the Nakaminato Groups were submitted to total organic carbon, total nitrogen and total sulfur analyses, Rock-Eval pyrolysis, and bitumen extraction. Saturate hydrocarbons fractionated from the bitumens were further analyzed by GC-MS.Only a small number of samples from the Kita-Ibaraki-oki TJ-1 and the MITI Joban-oki wells show good petroleum generation potential (S2≥2.5 mgHC/gRock). These samples also have high Hydrogen Index (≥250 mgHC/gCo). Two biomarker ratios, (C27+C29+C31)/(C24∼C34) of n-alkanes and C27/(C27+C29) of steranes, indicate an evident negative correlation, suggesting source organic input. Two other ratios, pristane/phytane and C35/(C31∼C35) of homohopanes, also indicate a negative correlation, suggesting oxic/anoxic depositional environment. All these ratios correlate to petroleum generation potential, and good potential is accompanied by low ratios in (C27+C29+C31)/(C24∼C34) of (C-alkanes and pristane/phytane, and high ratios in C27/(C27+C29) of steranes and C35/(C31∼C35) of homohopanes.These results suggest that the Cretaceous argillaceous rocks in the offshore Joban Basin can have good petroleum generation potential in case of abundant marine organic matter deposited under anoxic environment. For petroleum exploration in the east of the Abukuma Ridge, it is important to predict the regional distribution of Cretaceous argillaceous source rocks that are rich in marine organic matter and deposited under anoxic environment.
- 石油技術協会の論文
石油技術協会 | 論文
- 地震波シミュレーションが地下構造探査に果たす役割
- インバージョンテクトニクス
- 最近の探鉱プレイへの構造形成モデルの貢献
- 堆積盆地の地史情報に基づく沈降モデルと構造形成--日本海東部と中国北部湾を例にして (第55回石油技術協会総会地質・探鉱部門シンポジウム--堆積盆地評価とその応用)
- 東北裏日本海域における石油の生成と移動の時期 (「石油の生成と移動の時期」シンポジウム特集号)