吐哈盆地北部山前带构造样式及演化特征

吐哈盆地北部山前带地质结构复杂,地震资料品质差,油气勘探难度大。为寻求油气勘探新突破,利用地质、地震和钻井资料,对北部山前带构造样式进行重新梳理,通过构造物理模拟实验校正构造解释,建立更合理和准确的构造模型,系统分析该地区构造变形机理及变形规律。研究成果表明,北部山前带发育侏罗系煤层和二叠系泥岩双滑脱层,形成了以叠瓦状构造为主的逆冲推覆构造,垂向上为“入”字型冲断层、突起构造、叠瓦扇构造;滑脱层下面是堆垛状双重构造或叠瓦状双重构造;平面上受2组断层控制,呈南北成排、东西成段分布,由北向南依次为冲断带、逆掩带、逆掩带外缘构造带。研究区中东段推覆体下盘断背斜、断块构造群发育,形态完整,利于油气保存,是侏罗系油气勘探的有利区;逆掩带外缘构造带形态较为完整,是下侏罗统及之下层系油气勘探的潜力区。

Structural Style and Evolution of Northern Piedmont Belt in Turpan-Hami Basin

Complex geological structures and poor quality of seismic data make the northern piedmont belt difficult to be explored in the Turpan-Hami basin. In order to make new breakthroughs in oil and gas exploration, geological, seismic and drilling data is used to describe structural styles, conduct structural physical simulation to correct structural interpretation, and establish a more reasonable and accurate structural model to systematically analyze the mechanism and law of the structural deformation in the study area. The results show that double decollement layers (Jurassic coal seam and Permian mudstone) are developed in the northern piedmont belt and thrust nappe structures dominated by imbricated structures form, where zigzag thrust faults, protuberances and imbricated fans can be found vertically. Under the detachment layers, there are double stacked structures or double imbricated structures. In the plane, the piedmont belt is controlled by two groups of faults and the study area is divided into 3 rows of structural belts including thrust belts, overthrust belts and structural belts at the outer edge of the overthrust belts from north to south. The fault anticline and fault-block structural groups in the footwall of the nappe in the middle-east section of the study area are well developed with complete morphology, which are favorable for oil and gas preservation, and are the targets for risk exploration of Jurassic oil and gas. The structural belt at the outer edge of the overthrust belt with relatively complete morphology is a potential target for oil and gas exploration in the Lower Jurassic and its underlying strata.