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Microfossil Analysis Microfossil Analysis - Applications for Determining Geological Age and Reconstructing Paleoenvironments - S ummary It is important to recognize the distribution of source and reservoir rocks and the migration pathways for hydrocarbon entrapment. Microfossil analyses provide geological age, stratigraphic correlation and paleoenvironmental data. Multi-microfossil analysis provides more detailed geological age data and high-resolution correlation of strata. Microfossil analysis contributes to accurate assessment of the subsurface for oil and gas exploration. Because microfossil analysis can be performed quickly, it is suitable for wellsite operation. ᴾᴾᵫᶇᶁᶐᶍᶄᶍᶑᶑᶇᶊᴾ Microfossils Foraminifera Calcareous Nannofossils Diatoms 0.01mm Foraminifera Pollen 5-600 䡚 5-6000 species Radiolaria Nannofossils 5-6000 䡚 Diatom 5-6㽢10 species 0.05mm 0.05mm Microfossils can be detected and identi- Foraminifera have calcareous Calcareous nannofossils are Diatoms are microfossils of fied under a microscope. Characteristics tests with chambers and formed by phytoplankton as very phytoplankton with siliceous valves, that make microfossils useful are: apertures of various shapes, and small calcareous plates and an important source material for ӑ Their abundance in rock were the first microfossils used (coccoliths), and are particularly hydrocarbons. These microfossils are ӑ The ease and speed with which they in the oil industry. Both useful index fossil because of easily identified even from can be analyzed planktonic and benthic their worldwide distribution. fragments because of their ӑ Their availability for wellsite operation foraminifera exist. symmetric morphological patterns. -Geological Age- -Stratigraphic horizon and correlation- Age Diatom Zone㻌㻌㻌㻌Range and Photo Bioevent . 䕰K=Neodenticula kamtschatica (2.7) K Niigata area Akita area Plio. Sasaoka F. Haizume F. Grt. praeinflata U. Tentokuji F. 䕰H=Denticulopsis katayamae (8.7) D Nishiyama F. Grt. orientalis 䕰D=Denticulopsis dimorpha (9.3) L. Tentokuji F. 䕦D=Denticulopsis dimorpha v. dimorpha (10.0) Late Miocene Shiiya F. PD C䕰PD=Denticulopsis praedimorpha (11.4) Grt. ikebei Funakawa F. 䕦PD=Denticulopsis praedimorpha v. minor (12.7) U. Teratomari F. HY Spirosigmoilinella C䕰HY=Denticulopsis hyalina (13.1) compressa Onnagawa F. L L.Teratomari F. PL Warm water species Nishikurosawa F. 䕰PL=Denticulopsis praelauta (15.8) Nanatani F. abundant 䕦L=Denticulopsis lauta (15.9) Green Tf. Green Tf. Middle Miocene 䕦PL=Denticulopsis praelauta (16.6) 䕦=First occurrence䠈䕰=Last occurrence The occurrence of Grt. ikebei from the Niigata area well and its The occurrence of the fossil Diatom Denticulopsis dimorpha in a rock stratigraphic horizons in the Shiiya Formation in the Niigata area and sample indicates a Late Miocene geological age, from 10 million to 9.3 the Funakawa Formation in the Akita area. million years ago. -Sedimantary Sequence - Key points ⏕ᒙ‽Bioevent PaleodepthྂỈ῝ኚື Gamma Sedimentaryሁ✚䝅䞊 Cal.Nannofossils▼⅊㉁䝘䝜 1km Seismicᆅ㟈᥈ᰝ᩿㠃 profile (Benthicᗏ⏕᭷Ꮝ⹸໬▼ Foram.) ray sequence䜿䞁䝇 ໬▼⏘ฟ㔞abundance MFS㻌㻌 Analyses of foraminifera, calcareous nannofossils and diatoms can 䕦 (P)G.flexosa Ab(0.40) Deep be performed. MFS Shallow Sequence A SBSB SB 䕰(N)P.lacunosa(0.44) (1) From a small rock sample (5–6g to 100g), microfossil analysis HST results can be obtained, often in a short period of time. (R/L)G.truncatulinoides(P) MFS TST (2) Micropaleontology is a powerful tool for establishing a 㻌 㻌 Sequence B LST chronostratigraphic framework and reconstructing the SBSB SF SB paleoenvironment of a region. Multi-fossil analysis provides more P. “anula”CS (N) MFS 1st Trimosina A(B) 㻌 detailed geological age data and high-resolution correlation of strata. Sequence C (3) Microfossil analysis contributes to the interpretation of SBSB sequence stratigraphy, high-resolution reservoir stratigraphy 䕰(N)R.asanoi(0.91) MFS SB=sequence boudary and paleoenvironmental comparisons. Sequence D MFS=maximum flooding surface Microfossil analyses greatly contribute to the assessment of oil & This sedimentary sequence was interpreted with multi-fossil analysis, gas distribution. logging data and a seismic profile. Microfossil analysis provides geological horizon, fossil abundance, and paleodepth data. These results FRQWULEXWHGWRHVWLPDWLRQRIWKHUHVHUYRLU·VGLVWULEXWLRQ Challenge the future with innovative technologies .
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