Organic group separation and characterization of petroleum source rock extracts and crude oils by chromatographic and spectroscopic methods

Abstract

In the Atlas of NOl,th enl Tunisia stratifol"lll lead and zim' sulphide minel'alization 'lccu .. in laminated hlaek shales of tlH.' Cenomanian-Tunmian Bahloul Fonllatioll and as Bou (;rinc on'hocly alon~ a fault systcm throu~h Crdal~tOUS series. TIH' a~c, IIIl'chanism of minel'alization anti source of organic matter is still controversially discussl'd . The lH'ecipitation of hasc metals as sulphidcs in sediments I'c<juil'cs oq~anic matter as hydl'o~en SOUlTe hoth in thermochemical (Ahiolo~ical) and haduial (Biological) sulphatc rcduction. Bahloul Formation is an l'H~cllent l'X:IIUpk to study this phenomena, Threc scl'ies of 97 samplcs, were investigated with raJl~l' of geochcmical techniques: -Dctermination of total eal:hon (TC), total ol'ganic carhon (TOC), total sulphur (TS) hy LCl~O Ca"hon-Sulphtll' Detenllinatol'. -I~ock-E":II Pyrolysis of all the th,'ee sel'ks. - I~xtraction of hitUlllen with C H2Ci2 hy Soxhlet apparatus, -Separation of or~ank ~roups (lIyclt'ocadwJls) hy Column Chr'oll1atography (eC) into aliphatic, aromatic, hctero (NSO compounds) and asphaltenes. -(;as ch,'omato~raphy «;e) of aliphatk and aromatic fractions, -Derivation of NSO fnlctions and their Gas dlromatognlphy. -(;as chromatography and Mass spedromeh'y of selected sampll~s. -Biolll~II'kl'r identitication and quantitication in aliphatic fradions hy GC-MS. -Identitil'ation of individuall~ompollnds in hyd"oearhon fnldions (~J'CIups) hy (;C and GC-MS. Core, r'e,~sentativl' samples frolll on'hody and third sl'ries Wl'l'l' also invcstigatl'd hy (hgank Pelt'o~nlphy (Reflcet:lI1ce/Fluon~ sl'encc Minosl'opy), Inoq~anic geochemical analyst's hy X-I~ay Fluon'scellce (XRF) for ma.ior (Na, Mg, AI, Si, P, S, K, Ca, Ti, Mn '-'" Fe) and trace (V, Cr, Co, Ni, Cu, Zn, As, Rh, Sr, Zr, Ba, Ph, Th, Sc & Cd) eklllcn(s and isotopic dctenllinations hy Mass spectromet<~r (C '-'" 0 of carhonate, C isotopy of extnlet and kero~en) wen' made for representative samp!t's f,'om thn'e scrics, Analytical data ohtaincd from organk gcochemkal, inoq~ank gcochl~J1lical "mlly,'ics, isotopic determinations and microsCClpic measurements/ohservations were interpl'dl'd and ploHed to estahlish (liffl'n'lIl relationships and corrchltions to investigate thc followings: v -Richness, quality and maturity of organic matter. -O r igin and soun'c of organic mattcr. -Organic matter typing in scdiments of Bahloul Formation and Bou G rinc orehody. -Depositional environment of organic mattel". -llydmcarhon (petroleum) potential of Bahloul FOI"mation. -The abnonnal hiodegradation (Al'Omatic hydrocarhons dcgraded pr'ior to aliphath.' hydr"oc:lI"hons). -Altl~rati on in miner"al composition. -Mechanism of mineralization with rcfl~r"enCe to or"ganic matter. -Corrdation of hiodegradation and mineralization. Good correlation havc hecn found among the data coming from diffcrent an;,lytical techniques.