碎屑岩储层断裂带构造成岩作用和油气封堵特征研究

In hydrocarbon exploration and production, as faults can be either conduits or retarders for fluid flow, research on fault sealing capacity has attracted interests of petroleum geologists in the past decades. The proposition and improvement of multiple approach methodologies of evaluation on fault sealing capacity has significantly promoted the application of fault seal analysis in hydrocarbon exploration and production. However, in either fundamental research or practical application, the existing studies on fault sealing evaluation are mostly derived from the extensional geological settings with relative simple fault zone architecture, whereas the fault zone architecture and fault sealing mechanisms in the compressional geological settings are yet well-documented, particularly classification of structural diagenesis and resultant fault rocks developed within fault zones in compressional geological settings. Therefore, in order to reveal the important control of thrust fault evolution on fault zone structure, structural diagenesis and its hydrocarbon sealing capacity, this study in the Lenghu fold-and-thrust belt aims at: (i) revealing the thrust fault evolution and spatial distribution of the stress/strain by constructing the 3D geospatial structural models and geomechanical models of the Lenghu fold-and-thrust belt; (ii) quantitively depicting the structure of the thrust fault zone and building the 3D fault zone structural model, based on the detailed outcrop mapping and rock deformation characterization of well-exposed outcrops in field; (iii) defining the rock deformation mechanisms and evaluating the hydrocarbon sealing capacity of the fault rocks, by applying the methods of the Triangle Juxtaposition Diagram, Clay Smear Indices, Micro-structural Analysis, and Petrophysical Assessment, etc. Finally, this study focuses on the important control of thrust fault architecture on both the fault zone structure and its hydrocarbon sealing capacity within compressional geological settings.

断层既可作为油气运移通道也可形成有效封堵，故断层封堵引起了国内外石油行业的广泛重视。近年来，多种断层封堵评价方法的提出和完善，促进了断层封堵研究在勘探生产中的应用。然而，无论在基础研究层面还是实践应用层面，现有的断层封堵研究多针对断裂结构相对较为简单的张性断裂带，而压性断裂带结构复杂程度更高，其封堵机理尚不清楚，特别是压性断裂带构造成岩作用及断层岩类型有待阐明。本研究以柴北缘冷湖构造带为例：1）建立其三维构造模型和地质力学模型，明确断裂带演化过程和应力应变空间展布特征；2）通过逆断层典型露头的高精度解译，识别各断裂结构的岩石变形特征，对逆断层结构进行特征划分和定量表征，建立逆断层断裂带结构三维模型；3）分析断裂带岩石变形强度及变形机制，判别断裂带构造成岩作用和断层岩类型，并对断裂带油气封堵性进行半定量和定量评价。最后，综合评价逆断层演化过程对断裂带构造成岩作用及油气封堵性的控制作用。

断层既可作为油气运移通道也可形成有效封堵，故断层封堵引起了国内外石油行业的广泛重视。然而，无论在基础研究层面还是实践应用层面，前人开展的断层封堵研究多针对断裂结构相对较为简单的张性断裂带，而压性断裂带结构复杂程度更高，其封堵机理尚不清楚，特别是压性断裂带构造成岩作用及断层岩类型有待阐明。针对这些关键科学问题和技术难题，课题组2019-2022年开展了《碎屑岩储层断裂带构造成岩作用和油气封堵特征研究》，主要完成了四个方面研究内容。一是建立了三维构造模型和地质力学模型，明确了断裂带演化过程和应力应变空间展布特征；二是通过逆断层典型露头的高精度解译，识别了各断裂结构的岩石变形特征，对逆断层结构进行了特征划分和定量表征，建立了逆断层断裂带结构三维模型；三是分析了断裂带岩石变形强度及变形机制，判别了断裂带构造成岩作用和断层岩类型，并对断裂带油气封堵性进行了半定量和定量评价；四是综合评价了逆断层演化过程对断裂带构造成岩作用及油气封堵性的控制作用。研究发现：①研究区发育了微裂缝、碎裂带、微观涂抹带和硅酸盐混合变形带等4种微观构造类型；②变形带内粘土矿物含量是发育微观变形类型的主要控制因素，粘土矿物含量小于20%时主要发育碎裂带，粘土矿物含量大于50%时主要发育微观涂抹带，粘土矿物含量介于20%～50%之间时主要发育硅酸盐混合变形带；③微观构造的发育对研究区储层物性具有一定的影响，其中微裂缝的发育能够有效提高原岩孔隙度和渗透率，而微观变形带的发育对储层物性的改造作用较为有限。本项目的延续研究获批了国家自然科学基金面上项目（NO. 42272147）。相关研究成果以第一或通讯作者在Petroleum Exploration and Development、GSA Bulletin、Journal of Petroleum Science and Engineering、《石油勘探与开发》和《地球科学》等国内外石油地质领域权威期刊发表科技论文8篇，出版全英文专著1部；获中石化联合会科技进步一等奖1项（第3）、教育部科技进步二等奖1项（第4）；入选山东省泰山学者青年专家；获青岛市青年科技奖。