Reservoirs in the Sinian Dengying (DY) to Lower Cambrian Longwangmiao (LWM) formations in the central Sichuan Basin exhibit evident hydrothermal activities with pyrobitumen showing signs of alterations caused by hydrothermal fluids. However, few studies have explored the relationship between hydrothermal fluid activity and the evolution of natural gas accumulation, resulting in a significant lack of understanding of oil and gas accumulation history in the DY Formation. The impact of hydrothermal fluids on oil and gas accumulation in the DY Formation is substantial, and a correct understanding of the natural gas accumulation process and the identification of favorable exploration areas in the DY Formation require further research into hydrothermal cracking gas accumulation. By examining the filling features, optical textures, and structural characteristics of pyrobitumen and conducting geochemical studies on fluid inclusions trapped by hydrothermal minerals, this study explored the genesis of pyrobitumen in the DY to LWM formations. The relationship between hydrothermal fluid activity and oil cracking was also analyzed. The the pyrobitumen in the DY to LWM formations in the central Sichuan Basin were formed during hydrothermal fluid activity, exhibiting the same optical anisotropy characteristics as the mesophase pyrobitumen. Pyrobitumen can be divided into four types: fine-grained mosaic, medium-grained mosaic, coarse-grained mosaic, and streamline types. Its formation temperature exceeded 300 ℃, far surpassing the maximum burial temperature of the strata, indicating its hydrothermal fluid-driven genesis. The hydrothermal fluid activity occurred during the Late Permian and was related to the Emeishan mantle plume. The temperature of the hydrothermal fluids exceeded 300 ℃, leading to crude oil cracking in reservoirs of the DY to LWM formations. This study found that hydrothermal fluid activity advanced the cracking time of crude oil in the paleo reservoirs of the DY to LWM formations to the Late Permian, disrupting the existing accumulation model and helping us re-understand the evolution process of gas reservoirs and identify favorable accumulation areas.

针对鄂尔多斯盆地华庆地区长6油层组砂岩非均质性强、物性差,严重制约勘探与开发的问题,综合运用石油地质学、沉积岩石学、成藏动力学等理论,通过钻井、录井、测井资料,结合多种测试分析数据,对研究区长6油层组致密砂岩油藏成藏条件进行深入研究.研究结果表明,华庆地区B257井区长6致密砂岩油藏成藏主要受优质的烃源岩、良好的储层与油藏特征共同控制.最终依据油层组的沉积背景、构造条件、储层条件、烃源岩条件和生产情况确定了2个有利勘探区域.研究结果为华庆地区B257井区长6油层组致密砂岩油藏的勘探与开发指明了方向.

通过对子长采油厂L346井区长6储层岩心物性分析、 砂岩薄片鉴定分析和测井资料的整理和分析,研究了该区的"岩、 电、 物、 油"特征及它们之间的相互关系.子长采油厂L346井区长6储层主要是极细粒石英砂岩.在物性较好的细粒砂岩段其在测井曲线上的解释结论为油水层时,其电性特征为自然电位呈现负异常,自然伽马呈现低值以及电阻率中—高值

致密砂岩气藏,作为最为现实的未来油气资源的接替领域,与早期常规天然气气藏研究的不同在于其勘探思路及指导思想的不断转变.致密砂岩气勘探的重点集中于在有效生烃范围内寻找优质储层甜点,烃源岩和高效储层展布规律的研究是亟需解决的核心问题.高分辨率地震资料保幅处理、 曲线重构储层预测技术以及叠前AVO属性分析烃类检测方法三者有效结合,为实现致密砂岩气勘探取得突破提供了有效途径.