柴西地区渐新统膏盐岩的形成环境与发育模式
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宋光永(1985—),男,湖北武穴人,工程师,硕士,从事油气储层沉积学方面的研究。联系电话:15557154955,E-mail:305098792@qq.com。

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国家科技重大专项“大型岩性油气藏形成主控因素与有利区带评价”(2017ZX05001-002),中国石油天然气股份有限公司重大科技专项“柴达木盆地建设高原大油气田勘探开发关键技术研究与应用”(2016E-01)和“湖相碳酸盐岩成因模式与有利储集相带预测”(2016B-0303)。


Forming environment and development modes of the Oligocene lacustrine gypsum-salt rock in western Qaidam Basin
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    摘要:

    对柴西地区渐新统膏盐岩的形成环境、成因及分布规律认识不清,制约了油气勘探进展。利用沉积岩石学和 地球化学等方法,研究膏盐岩岩石类型及特征、沉积时期水体性质、时空分布特征及发育模式。结果表明:柴西地 区渐新统下干柴沟组上段膏盐岩以层状石盐为主,其次为石膏岩和少许钙芒硝及芒硝,膏盐晶体自形程度高,为原 生沉积作用形成;膏盐岩主要发育于水退浓缩沉积序列的晚期,古水体环境具有半咸化-咸化、还原、深水和低温等 特征,表明湖水蒸发浓缩过饱和结晶是膏盐岩的形成机制。膏盐岩纵向分布受控于湖平面升降,发育6个集中成盐 期;平面分布受控于湖底沉积古地貌,呈局限环带状分布且存在多个次级聚盐中心。根据柴西地区渐新统湖盆古 水体的演化阶段,将膏盐岩发育模式分为咸化阶段晚期和广盐湖期2种。早期膏盐岩的平面分布相对局限,主要形 成于洼陷区;晚期拓展至低隆起区,分布广泛。

    Abstract:

    The forming environment,genesis and distribution rule of the Oligocene lacustrine gypsum-salt rock in western Qaidam Basin have been not clear for a long time,which hinders the progress of petroleum exploration. In order to solve these problems,the sedimentary petrology and geochemical methods were used to study the types and characteristics of gypsum-salt rock,the nature of water bodies during deposition,temporal and spatial distribution and development modes. The results show that the Oligocene gypsum-salt rock in the lower Ganchaigou Formation in western Qaidam Basin is mainly layered halite,followed by gypsum rock,a little glauberite and mirabilite,and it is well euhedral and formed during primary deposition. The gypsum rock is mainly developed at the late stage of water regressive deposition. The sedimentary paleoenvironment has the characteristics of semi-saline and saline brackish and deep water,anoxic water body and low temperature.Its formation mechanism is that the crystalline precipitates due to the evaporation and concentration in a supersaturated lake. The vertical distribution of the gypsum rock is controlled by the fluctuation of lake level. There are 6 key salt-forming periods. The gypsum-salt rock is confined in a zonal distribution in the plane with multiple sub salt-forming centers,which is controlled by the paleomorphology of the lake bottom. Based on the evolution of the Oligocene water body of the lake basin in western Qaidam Basin,there are mainly two development model-the late salinization stage and the wide salt lake stage. In the early stage,the development of gypsum-salt rock mainly formed in the depression area with a limited distribution,while in the late stage,the gypsum-salt rock was distributed widely,extending to the low amplitude uplift area.

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宋光永,夏志远,王艳清,朱超,田明智,李海鹏.柴西地区渐新统膏盐岩的形成环境与发育模式[J].油气地质与采收率,2018,25(5):50~56

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  • 在线发布日期: 2018-09-13