鄂尔多斯盆地西南部上古生界天然气成藏动力研究

发布时间：2018-11-19 07:10

【摘要】：本文在对研究区多口探井的钻井、测井、分析化验等静态资料与试气、试采等动态资料分析的基础上,对鄂尔多斯盆地西南部上古生界天然气藏的成藏动力来源、古流体压力状态、异常高压成因以及增压大小进行了深入研究,并进一步将动力与成藏联系起来,总结其成藏动力模式。主要取得了以下认识:通过流体包裹体测试分析,对研究区上古生界盒8、山1段储层古压力进行恢复,结果显示上古生界石盒子组及山西组存在古超压,主要为弱超压-超压系统。前人认为鄂尔多斯盆地上古生界石盒子组、山西组古超压的成因主要为压实不均衡导致的,但本次研究从沉积速率、测井响应、生烃强度、成岩等多方面进行论证认为古超压成因主要为生烃引起的增压。建立煤系烃源岩生烃增压的数值模型并进行计算得出,超压形成时期主要发生在晚侏罗世、早白垩世气藏进入大量生烃期之后,并且累计生成的超压与试气产量有一定的正相关性,间接说明了形成超压的主要成因为生烃超压,并且这种超压作为油气运移的主要动力,为成藏起到了一定的贡献作用。综合各项研究结果,研究区成藏动力模式主要有两种,一种是早白垩末期之前烃源岩生烃作用形成的巨大压力是天然气运移的重要动力源,由于研究区在地史中缺乏天然气的大规模侧向运移的条件,天然气主要在异常压力驱动下以幕式涌流方式进行运移,主要为垂向、近距离、快速成藏,代表为研究区山1气藏。而在早白垩世末期地层被抬升剥蚀之后,由于温度、压力、应力的下降,生烃增压没有能量的供给无法再成为天然气运移的动力,后期主要是在天然气浓度差的作用下通过做扩散运移,代表为研究区盒8气藏。
[Abstract]:Based on the static data of drilling, logging and analysis of many exploration wells in the study area and the dynamic data of gas test and production test, this paper analyzes the source of reservoir forming power of the Upper Paleozoic natural gas reservoir in the southwest of Ordos Basin. The pressure state of paleofluid, the origin of abnormal high pressure and the size of supercharge are deeply studied, and the dynamic model of reservoir formation is summarized. The main results are as follows: through the fluid inclusion test and analysis, the paleo pressure of the Upper Paleozoic Box 8 and the first member of the Shan formation in the study area has been restored. The results show that there is paleo overpressure in the Upper Paleozoic Shihezi formation and Shanxi formation. Mainly for the weak overpressure-overpressure system. It is believed that the origin of paleo overpressure in Upper Paleozoic Shihezi formation and Shanxi formation in Ordos Basin is mainly caused by uneven compaction. However, this study is based on sedimentation rate, log response and hydrocarbon generation intensity. Diagenesis and other aspects demonstrate that the origin of paleo-overpressure is mainly caused by the pressurization caused by living hydrocarbons. The numerical model of hydrocarbon generation pressure in source rocks of coal measures is established and calculated. It is concluded that the formation of overpressure occurred mainly in the late Jurassic and after the early Cretaceous gas reservoir entered a large hydrocarbon generation period. And there is a positive correlation between accumulative overpressure and gas production, which indirectly shows that the overpressure is mainly caused by hydrocarbon generation overpressure, and this overpressure, as the main driving force of oil and gas migration, plays a certain contribution to reservoir formation. Based on the results of various studies, there are mainly two types of dynamic models for reservoir formation in the study area. One is that the huge pressure formed by hydrocarbon source rock hydrocarbon generation before the end of early Cretaceous is an important power source for natural gas migration. Due to the lack of the condition of large-scale lateral migration of natural gas in the study area, natural gas is mainly transported by curtain inrush flow driven by abnormal pressure, mainly vertical, short distance, rapid accumulation, represented by mountain 1 gas reservoir in the study area. After the strata were uplifted and denuded at the end of the early Cretaceous, because of the decrease of temperature, pressure and stress, the hydrocarbon-generating pressure could not become the driving force of natural gas migration without energy supply. In the later stage, diffusion migration is mainly done under the action of gas concentration difference, which is represented by box 8 gas reservoir in the study area.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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