普光地区千佛崖组构造–沉积特征研究

Study on the Tectonic-Sedimentary Characteristics of the Qianfoya Formation in Puguang Area

摘要: 四川盆地侏罗系千佛崖组页岩油气勘探前景良好，但目前对于该区域千佛崖组构造、沉积特征的研究还不够深入。为此，利用构造地质学、沉积学原理，依据岩心、测井、地震等资料，通过地震属性体提取、岩心精细描述等技术手段，精细描述了该地区区域构造特征、构造形态及断裂系统，划分了普光千佛崖组一段(简称千一段)沉积相及平面展布特征。研究表明：普光千佛崖组东向斜受毛坝东断层与东岳庙东断层控制，向南西抬升，发育北西向小断层，多消失于千佛崖组，有着较好的天然气保存条件。千一段整体为湖泊–三角洲沉积体，页岩气层为半深湖沉积，厚度25 m左右，全区发育稳定；致密气层为三角洲前缘沉积，东向斜发育3条复合河道，1号河道最为发育，砂体厚度平均16~36 m，页岩气和致密气之间隔层厚度为30 m左右，有着较好的开发潜力。

Abstract: The Jurassic Qianfoya Formation shale oil and gas exploration in the Sichuan Basin shows promising prospects. However, the current research on the structural and sedimentary characteristics of this area’s Qianfoya Formation is not yet thorough. Therefore, we have utilized principles from structural geology and sedimentology, combined with data from core samples, well logging, seismic surveys, and other sources. Through techniques such as seismic attribute extraction and detailed core description, we have provided a comprehensive depiction of the region’s structural features, morphology, fracture systems, as well as delineated the sedimentary facies and spatial distribution characteristics of the Puguang Qianfoya Formation segment (referred to as Segment One). The study reveals that the Puguang Qianfoya Formation is influenced by both the Maoba East Fault and Dongyuemiao East Fault resulting in an eastward tilt with uplift towards southwest direction. Multiple small faults develop in northwest direction but most disappear within the Qianfoya Formation while exhibiting favorable conditions for natural gas preservation. The entire Segment One represents a lacustrine-deltaic depositional system where shale gas layers form approximately 25 m thick within central lake areas; whereas tight gas layers are developed at delta fronts with three compound river channels forming at eastward tilting regions-among which Channel 1 exhibits significant development with sand body thickness averaging between 16~36 m. The interlayer thickness between shale gas and tight gas is around 30 m indicating good potential for development.