厘定油气运移-油藏充注砂岩输导层的地球物理-地球化学新方法

Since the carrier bed is a pathway of the oil migration and reservoir filling, it is an important foundation where the formation of the oil/gas field is studied and deployment of exploration is planned. The carrier beds involve the oil and gas conduit performance in various types such as porous clastic rock (e.g., sandstone), the karst pore-cavern-fracture network layer, unconformity surface and the fault. Petroleum geology communities both in China and overseas have so far paid much attention to the identification of the carrier beds, mainly focusing on macroscopic analysis based on the geological concept. There is the lack of a direct method that can identify and verify the effective carrier beds. In view of different contents and methods in various types of carrier beds, this interdisciplinary research application aims to directly identify the oil migration in the carrier beds of sandstone reservoir, based on the integration of petroleum geological, geochemical and geophysical theory and methods. Specifically, the driving force and the restraining force of fluid migration in sandstone layer are to be measured and evaluated along the one-dimensional drilling profile by integrating geophysics well-logging methods. The sandstone layers, which driving force is greater than the restraining force, will be quantitatively characterized and optimally selected. Second, the geochemical reservoir bitumen analysis techniques are used to test whether the selection is rich in residual oil migration. The sandstone layer, where the oil migration or filling has been positively identified, will be recognized as the carrier bed. Finally, by comparing the sublayers of the carrier beds between different wells, the distributions of the carrier beds in the plane and spatial dimensions will be studied, which can provide effective foundation towards a prospect exploration.

输导层是油气运移与油藏充注的通道，也是油气成藏研究与勘探部署的重要依据，其内涵涉及孔隙性碎屑岩层（如砂岩）、岩溶性孔洞-裂隙网络层、不整合面以及断层等的油气输导性能。国内外石油地质界非常关注输导层的判识与研究，但对于输导层的研讨迄今大多仍基于地质理念的宏观分析，缺乏厘定与验证有效输导层的直接手段。鉴于不同类型的输导层研究内容与方法的差异性，本申请拟从砂岩油藏入手，通过石油地质-地球化学与地球物理学理论与方法的跨学科交叉研究，直接厘定油气运移输导层，即综合地球物理测井方法，沿钻井剖面在一维尺度上测定与评价砂岩层流体运移动力与阻力，定量表征并优选出动力大于阻力具备油气输导能力的砂岩层，再采用油藏地球化学储层沥青分析技术，检验其中是否确实富含残留运移烃类，将证明发生过油气运移或充注的砂岩层厘定为输导层。最后通过井间输导层小层对比，在平面与空间尺度上研究输导层的展布，为预测有利的勘探区带提供依据。

油气运移输导层的有效检测是油气勘探研究的难题。本项目通过不同学科理论与方法的交叉研究，发展了一种直接检测油气运移砂岩输导层的新方法。根据研究区地下油气藏的油气和水的密度及油气柱高度，建立了油气运移动力模型。发展了基于测井资料建立油气运移阻力模型的两种方法。第一种方法是基于常规测井资料，结合岩心实验分析数据，利用岩心刻度测井的方法建立了研究区的泥质含量、孔隙度、渗透率、油气运移阻力模型。第二种方法是基于核磁共振测井资料建立油气运移阻力模型，将核磁共振测井采集的原始回波串数据通过降噪、数据压缩以及反演，得到横向弛豫时间T2分布，发展了扩展幂函数法将T2分布转化为随测井深度连续变化的毛管压力曲线，获取油气运移阻力。依据油气运移动力学原理，沿钻井剖面在一维尺度上定量表征出动力大于阻力具备油气输导能力的砂岩层，结合油藏地球化学储层沥青分析结果及录井数据，确定单井中的砂岩输导层。绘制了研究区多井连井剖面，在平面与空间尺度上研究了砂岩输导层的展布，综合储层沥青分子地球化学信息，示踪了研究区油气运移方向。