塔里木盆地克拉苏构造带西部构造变形规律与油气勘探方向

塔里木盆地库车坳陷克拉苏构造带西段变形较复杂,深层地震资料成像不理想,圈闭发现与落实难度大,油气勘探开发程度低。为了加快该区的油气勘探进程,基于前人的研究成果,利用最新的钻井信息、高品质三维地震资料,在分析克拉苏构造带不同区段构造变形特征的基础上,研究了构造带构造差异变形的规律、构造变形特点及构造样式,剖析了克深断裂带突发构造集中发育的成因,并指出了该区下一步的油气勘探方向。研究结果表明:①塑性膏盐岩、区域挤压应力、基底先存构造等3因素分段主控构造差异变形规律;②大北段主要受双盐湖的影响,发育楔形冲断叠瓦构造;③博孜—大北区段受斜向挤压、双盐湖及古隆起等3个因素的影响,发育完整突发构造样式、雁列式大规模推覆构造样式及楔形冲断叠瓦构造样式;④博孜区段主要受古隆起阻挡,发育破碎型突发构造样式;⑤阿瓦特—博孜区段构造转换带主要受应力斜向挤压及单盐湖的影响,发育楔形冲断叠瓦构造样式。结论认为,克深断裂构造带、拜城断裂构造带内普遍发育的突发构造群、雁列式圈闭群具有巨大的油气勘探开发潜力,是该区重要的勘探对象。

Structural deformation laws and oil & gas exploration direction in the western Kelasu tectonic zone of the Tarim Basin

The western section of Kelasu tectonic zone in the Kuqa Depression of the Tarim Basin is faced with a series of difficulties such as complicated deformation, poor deep reservoir seismic imaging, difficult trap discovery and confirmation and low oil & gas exploration and development degree. In order to speed up the oil and gas exploration in this area, this paper analyzed the structural deformation characteristics in different sections of the Kelasu tectonic zone based on previous research results, combined with the latest drilling information and high-quality 3D seismic data. Then, differential structural deformation laws, structural deformation characteristics and structural patterns of the Kelasu tectonic zone were studied, and the reasons for the intensive development of pop-up structures in the Keshen fault belt were analyzed. Finally, the oil & gas exploration direction in this area in the next step was pointed out. And the following research results were obtained. First, the differential structural deformation laws are controlled by three major factors in different sections, namely plastic gypsum-salt rock, regional compression stress and basement pre-structure. Second, under the effect of twin salt lakes, wedge-shaped thrust imbricated structures are developed in the Dabei Block. Third, the Bozi–Dabei Block is under the joint effect of oblique compressions, twin salt lakes and paleo-uplifts, and complete pop-up structures, large-scale echelon nappe structures and wedge-shaped thrust imbricated structures are developed. Fourth, the Bozi Block is hindered mainly by the paleo-uplift, and broken pop-up structures are developed. Fifth, the structural transition zone of Awate–Bozi Block is mainly affected by oblique compression stress and single salt lake, and wedge-shaped thrust imbricated structures are developed. In conclusion, pop-up structure group and echelon trap group that are generally developed in the Keshen fault belt and the Baicheng fault belt have huge oil & gas exploration and development potential, so they are the important exploration objects in this area.