应用定量颗粒荧光技术恢复塔中地区石炭系油气充注历史

The application of quantitative grain fluorescence technique to restore the hydrocarbon charge history of Carboniferous reservoirs in Tazhong area,Tarim Basin

塔中地区经历了复杂的构造演化,给油气成藏研究带来了挑战。为恢复塔中地区石炭系的油气充注历史,利用定量颗粒荧光(QGF和QGF-E)技术开展了详细研究。结果表明,在TZ421井现今油水界面之下存在古油层和残余油层,前者位于-2 510～-2 610m,古油水界面位于-2 610 m,后者位于-2 510～-2 570 m,残余油水界面位于-2 570 m。在TZ103井的现今气水界面之上存在古油层,位于-2 555～-2 605 m,古油水界面位于-2 605 m。结合成藏条件分析认为,TZ421井中存在厚度100 m的古油层,表明晚海西期轻质油充注规模大,随后在燕山期发生两次泄漏,在喜马拉雅期天然气充注过程中形成凝析气顶。TZ103井现今凝析气层中存在厚度为50 m的古油层,表明在凝析气藏形成之前,在晚海西期有轻质油充注,古油层保存较好,在喜马拉雅期天然气充注过程中形成凝析气藏。利用定量颗粒荧光技术准确地恢复了塔中地区石炭系2期油气充注过程,为油气充注历史研究提供了新的可靠证据。

The Tazhong area experienced complexed structural evolution, which makes studies on hydrocarbon accumulation in this ar- ea more challengeable. In order to restore the hydrocarbon charge history of this area, we carried out a study the quantitative grain fluorescence （QGF and QGF-E） techniques was carried out. The results show that a palaeo-oil zone and a residual oil zone exist be low the present oil-water contact in Well TZ421, the former having a strong QGF response is distributed between - 2 510 m and - 2 610 m with a paleo-oil-water contact at - 2 610 m, while the latter with a strong QGF-E response is located between-2 510 m and - 2 57（I m with a residual oil water contact at - 2 570 m. In addition, above the current gas-water contact of Well TZ103, a palaeo oil zone can be observed between - 2 555 m and - 2 605 m with a paleo oil-water contact at - 2 605 m. The geological conditions for hy- drocarbon accumulation indicate that the paleo-oil zone with a thickness about 100 m in well TZ421, due to a large-scale charging of light oils. Charge in late Hercynian, and two episodes of oil leakage later in Yanshanian, and the formation of condensate gas cap during the Himalayan gas a 50m-thick paleo oil zone within the present condensate gas reservoir in well TZ103, suggesting a light-oil charge in late Hercynian before the formation of the condensate gas reservoir, which is formed by the Himalayan gas charge and does not destroy the previous paleo oil zone substantially. The reservoir of Well TZ421 is believed to have been charged initially down to 2610m, the depth of the paleo-oil-water contact. The presence of a 60 m-thick residual oil zone below the current oil water contact, as delineated by the QGF-E response, suggested that the paleo-oil zone leaked in two episodes and part of the oil column lost quite recently. The strong QGF response of the current gas-condensate zone in the two wells indicated that the initial- ly charged oil is subsequently partly dissolved in gas. Two episodes of the Carboniferous hydrocarbon charging history can be re- stored by applying quantitative grain fluorescence techniques, and this work provides new evidence for researches on hydrocarbon accumulation history in this area.