北方重要盆地油气资源战略选区调查工作进展

北方重要盆地蕴藏着丰富的油气资源,是我国陆上油气资源增储上产的重点地区。“十三五”以来,公益性油气地质调查聚焦国家需求,着力推进“四新”(即新区、新层系、新类型、新领域)油气调查与评价,强力支撑了油气体制改革,取得了塔西北沙井子构造带西段油气调查新发现,以及塔里木盆地数字化建设与选区评价、塔东北奥陶系、塔西北寒武系、三门峡盆地古近系和准东及其周缘地区石炭系油气基础调查等多项新进展;形成了数字盆地标准方案,塔里木盆地电阻率-极化率异常解释图版2项科技创新成果;支撑新疆地区油气勘查开采体制改革工作取得实效,助力企业在塔里木盆地东部超深层油气勘探快速实现新突破,有效推动地方经济和社会发展。

Distribution Features of the Nanhua-Sinian Rifts and their Significance to Hydrocarbon Accumulation in the Tarim Basin

On the basis of reprocessing 34 new two-dimensional spliced long sections(20,191 km) in the Tarim Basin, the deep structure features of the Tarim Basin were analyzed through interpreting 30,451 km of two-dimensional seismic data and compiling basic maps. Seismic interpretation and geological analysis conclude that the Nanhua-Sinian strata are a set of rift-depression depositional systems according to their tectonic and depositional features. The rift valley formed in the Nanhua Period, and the transformation became weaker during the late Sinian Period, which eventually turned into depression. From bottom to top, the deposited strata include mafic igneous, tillite, mudstone, and dolomite. Three major depocenters developed inside this basin during the rift stage and are distributed in the eastern Tarim Basin, the Awati area, and the southwestern Tarim Basin. Among them, the rift in the eastern Tarim Basin strikes in the near east-west direction on the plane and coincides with the aeromagnetic anomaly belt. This represents a strong magnetic zone formed by upwelling basic volcanic rock along high, steep normal faults of the Nanhua Period. Controlled by the tectonic background, two types of sedimentary systems were developed in the rift stage and depression stage, showing two types of sequence features in the Sinian depositional stage. The Nanhua System appears as a wedge-shaped formation, with its bottom in unconformable contact with the base. The rifting event has a strong influence on the current tectonic units in the Tarim Basin, and affects the distribution of source rock in the Yuertus Formation and reservoir beds in the Xiaoerbulake Formation in Lower Cambrian, as well as the gypseous cap rock in Middle Cambrian. The distribution features of the rifts have important and realistic significance for determining the direction of oil and gas exploration in the deep strata of the Tarim Basin. Comprehensive analysis suggests that the Tazhong region is the most favorable zone, and the Kalpin-Bachu region is the optimal potential zone for exploring sub-salt oil and gas in deep Cambrian strata.

Sedimentary characteristics and main controlling factors of the Middle-Upper Permian and Middle-Upper Triassic around Bogda Mountain of Xinjiang,NW China

Based on field geological survey,interpretation of seismic data and analysis of drilling and logging data,the evolution of geological structures,stratigraphic sedimentary filling sequence and sedimentary system around the Bogda Mountain were analyzed according to the idea of"structure controlling basin,basin controlling facies and facies controlling assemblages".The tectonic evolution of the basin around the Bogda Mountain can be divided into nine stages.The Middle-Late Permian–Middle-Late Triassic was the development stage of intracontinental rift,foreland basin and inland depression basin when lake,fan delta and braided river delta sedimentary facies developed.Early intracontinental rifting,late Permian tectonic uplift,and middle-late Triassic tectonic subsidence controlled the shape,type,subsidence rate and sedimentary system evolution of the basin.The Bogda Mountain area was the subsidence center and deposition center of the deep water lake basin in the Middle Permian with mainly deep-water deposition and local gravity flow deposition.This area had tectonic inversion in the Late Permian,when the Bogda Mountain uplifted to form a low bulge and a series of fan delta sand bodies.In the Middle-Late Triassic,subsidence occurred in the Bogda low uplift,characterized by extensive development of braided river delta deposits.

塔里木盆地东南坳陷侏罗系展布特征研究

塔东南坳陷位于塔里木盆地的东南部,勘探程度较低。侏罗系为该区主要油气勘探目的层,明确塔东南坳陷侏罗系展布特征是实现该区油气突破的关键问题。通过分析2015年后实施的最新钻探工程以及最新采集处理的地震、电法剖面,结合钻测井、露头资料,研究塔东南侏罗系分布范围及厚度,结果表明侏罗系在塔东南坳陷广泛发育,仅在且末凸起西部局部地区缺失;瓦石峡凹陷侏罗系十分发育,沉积厚度大,分布范围广,并向阿尔金山前有明显加厚趋势,可作为塔东南坳陷油气勘探目标区。

塔里木盆地沙漠区深层地震剖面拼接和深层成像技术

塔里木盆地深层油气资源丰富,由于缺乏支撑深层油气勘探的盆地级二维地震剖面,塔里木盆地深层油气勘探始终无法取得大规模突破。针对塔里木盆地沙漠区深层地震资料接收能量弱、信噪比低、各种干扰发育、二维格架测线资料品质差异大等诸多问题。本文采用微测井约束拟三维层析静校正、一致性处理、叠前“六分法”综合去噪等技术手段来解决静校正、一致性、信噪比等问题。在此基础上,进一步通过高精度拉东变换、聚束滤波结合近道内切除,消除多次波的影响,达到去伪存真的效果。最后通过共反射面元叠加成像、τ-p信号增强、低频拓展等深层信号增强技术改善深层成像。通过以上多种配套技术的综合应用,提高了塔里木盆地深层大剖面地震资料的成像效果,证明了这些技术在塔里木盆地沙漠区深层成像的可行性和实用性。

塔里木盆地柯坪断隆构造特征及油气勘探潜力

基于非地震资料的认识和一系列二维地震剖面的精细解释,剖析了柯坪断隆的构造属性、构造演化和断裂系统,划分了内部构造单元。研究认为:柯坪断隆为塔里木盆地的一部分,是盆地的一级构造单元;受不同断裂控制,柯坪断隆可分为3个构造分区,即东段阿克苏区、中段柯坪区和西段西克尔区,分别发育不同的构造样式;柯坪断隆经历了加里东期、海西期、印支期—燕山期、喜马拉雅期等多期构造运动,最终形成了现今的隆-坳格局。油气地质条件综合分析表明,柯坪断隆发育优质烃源岩、良好的生-储-盖组合和古隆起背景,沙井子构造带志留系天然气圈闭资源量达0.2018×10^(12)m^(3),柯坪断隆震旦系—寒武系深层石油资源量为16.84×10^(8)t,油气勘探潜力巨大。其中,阿克苏区的古生界、新生界构造-岩性圈闭,以及柯坪区和西克尔区的寒武系盐下隐伏构造是主要的油气勘探目标。