环县-正宁地区延长组长9沉积体系及沉积演化特征研究

以鄂尔多斯盆地环县—正宁地区三叠系延长组长9为研究对象,结合野外露头和岩心观察及测井资料分析,通过点、线、面研究步骤,精细刻画研究区延长组长91、长92沉积相特征及演化规律,为后期石油勘探开发做好指导工作。研究表明:环县—正宁地区的沉积相类型为辫状河三角洲相和湖相沉积;其中辫状河三角洲平原亚相在露头区最为典型,辫状河三角洲前缘亚相是研究区的优势相带;长92比长91砂体更发育,西部比西南部和南部砂体更发育;长92沉积时期,辫状河三角洲平面展布趋势大致分为东西向和北东—南西向,按照区域可以分为4支三角洲;长91沉积时期辫状河三角洲沉积相比长92时期具有很好的继承性。

The Sedimentary Phase Characteristics and Evolution Rule of Chang 9 in Huanxian-Zhengning Area

The paper chooses Chang 9 of triassic Yanchang Formation as the study object,which is in Huanxian-Zhengning area of the Ordos Basin.Based on field outcrops,core observations and log data analysis,the sedimentary phase characteristics and evolution rule of Chang-91 and Chang-92 were analyzed from the aspects of point,line and surface.The study shows that the sedimentary phase type in Huanxian-Zhengning area is braided river delta phase and lacustrine phase.The braided river delta plain subphase is the most typical in the outcrop area,while the delta front subphase is the dominant phase zone of the study area.Chang-92 sand body is more developed than Chang-91 according to the longitudinal evolution;sand body in the west is more developed than that in the southwest and south.During the deposition period of Chang-92,the braided river delta,further divided into four smaller deltas,is roughly stretching in the east-west and the northeast-southwest direction.The braided river delta sedimentary phase in Chang-91 sedimentary period has much inheritance than that of in Chang-92.