Origin and evolution of oilfield waters in the Tazhong oilfield, Tarim Basin, China, and their relationship to multiple hydrocarbon charging events
Origin and evolution of oilfield waters in the Tazhong oilfield, Tarim Basin, China, and their relationship to multiple hydrocarbon charging events
复制标题
塔里木盆地塔中油田油田水成因、演化及其与多次油气充注事件的关系
DOI：
10.1016/j.marpetgeo.2018.09.018
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发表时间：
2018-12-01
影响因子：
4.2
通讯作者：
Xiao, Zhongyao
中科院分区：
文献类型：
--
作者：
Chen, Jian;Liu, Dayong;Xiao, Zhongyao
对塔中油田奥陶系灰岩储层中的油田沃茨进行了化学和同位素研究，以追踪沃茨的来源和演化，并论证其与油气充注的可能关系。测定了油田沃茨的元素化学（Cl、Br、SO 4、I、K、Na、Ca、Mg和Sr）和多种同位素组成（δ D、δ O-18、Sr-87/Sr-86和129 I/I）。结果表明，这些油田沃茨含有三个阶段的入渗，沿着与大气降水的贡献较小。在晚志留世和石炭纪期间，大气降水似乎已经向下渗透。最早期卤水含碘量很低（<5.65mg/L），在晚奥陶世由贫有机质的寒武系向上迁移至下奥陶统白云岩;第二次卤水含碘量高（> 50 mg/L），来源于寒武系泥质烃源岩，向上运移进入奥陶系储层。这一阶段与志留纪和泥盆纪原油从烃源岩向储层运移的主要时期有关。这两种盐水都含有来自石灰岩储集岩的恒定水平的裂变I-129（11.8-47.0原子/μ L）。最后，具有非常低的I含量但较高I-129（106-491原子/μ L）的盐水开始向上迁移并渗入储层。考虑到相对较高的裂变I-129，这一阶段可能发生在晚新生代，并与来自相同源岩的干气运移有关。结合前人对该盆地其他油田的研究结果，认为油田沃茨演化可以作为油气成藏事件的制约因素，而油气成藏事件的发生和演化最终受控于区域构造运动和局部地质因素。
We conducted a chemical and isotopic study of oilfield waters from Ordovician limestone reservoirs in the Tazhong oilfield (Tarim Basin, China) to trace the origin and evolution of the waters, and to demonstrate their possible relationship with hydrocarbon charging. The elemental chemistry (Cl, Br, SO4, I, K, Na, Ca, Mg, and Sr) and multiple isotopic compositions (delta D, delta O-18, Sr-87/Sr-86, and 129 I/I) of the oilfield waters were determined. The results show that these oilfield waters contain basinal brines that infiltrated in three stages, along with a lesser contribution from meteoric water. The meteoric water appears to have infiltrated downwards during the late Silurian and Carboniferous. The earliest brine had very low I contents (< 5.65 mg/L) and migrated upwards from organic-poor Cambrian to Lower Ordovician dolostones during the Late Ordovician. The second brine had high I contents (> 50 mg/L), was derived from Cambrian argillaceous source rocks, and migrated upwards into Ordovician reservoirs. This stage was related to the main period of migration of crude oils out of the source rocks into reservoirs during the Silurian and Devonian. Both of these brines incorporated constant levels of fissiogenic I-129 from the limestone reservoir rocks (11.8-47.0 atom/mu L). Finally, brine with very low I contents, but higher I-129 (106-491 atom/mu L), began to migrate upwards and infiltrate reservoirs. Given the relatively high fissiogenic I-129, this stage may have occurred during the late Cenozoic, and was associated with migration of dry gas from the same source rocks. Our results, combined with those of a previous study of other oilfields in the basin, suggest that the evolutionary of oilfield waters can be used to constrain hydrocarbon accumulation events, and both of which were ultimately controlled by regional tectonism and local geological factors.