塔里木盆地塔河地区东部阿克库勒组阿四段条带状砂体成因再认识

塔里木盆地塔河油田三叠系阿克库勒组阿四段发育多条条带状砂体，为塔河油田主要碎屑岩油藏之一，前人研究多认为此类砂体为三角洲前缘水下分流河道沉积，但在成因解释方面存在一些矛盾，因而有必要开展新研究。从研究区岩性、粒度、沉积构造、相序等方面分析，显示阿四段属于湖盆边缘滨湖—浅湖环境沉积，条带状砂体为滨浅湖砂坝成因。依靠地震储层预测成果等，在研究区识别出了3期砂坝，并在研究区西部和东部发现2个季节性朵叶体，该区域内的砂体经过后期湖浪的改造后形成滨浅湖砂滩。参考前人地层、沉积等研究成果，提出研究区发育多期次滨浅湖砂坝沉积模式，认为塔河油田东部地区阿四段沉积时期辫状河三角洲控制面积变小，从而形成了大面积分布的滨浅湖环境，在滨浅湖环境内发育了多期次砂坝。

A new understanding of the causes of the banded sand body in the fourth member of Akekule Formation,eastern Tahe Oilfield,Tarim Basin

There are several banded sand bodies in the fourth member of the Triassic Akekule Formation in eastern Tahe Oilfield, Tarim Basin, and it is one of the major clastic rock reservoirs in Tahe Oilfield. Previous studies suggested that the origin of the sand was the distributary channel of delta front, but there are some problems about the origin and the characteristics of the sand body, so we did this research. The lithology, granularity, sedimentary structure and facies sequence of the study area are analyzed. The fourth member of Akekule Formation was deposited in shore-shallow lacustrine environment, and the origin of the banded sand is the shore-shallow lacustrine sandy bar. Based on the seismic reservoir prediction results in the work area, three sandy bars were found, and two seasonal lobes of delta were also found in the east and west parts of the area which were turned into shore-shallow lacustrine sandy beach by the lake wave. Finally we put forward the sedimentary model of shore-shallow lacustrine sandy bars of Akekule Formation in eastern Tahe Oilfield, when the fourth member of Triassic Akekule Formation in eastern Tahe Oilfield was deposited, the area of braided river delta was reduced, and the area of the shore-shallow lake was raised, so the shore-shallow lacustrine sandy bars was deposited in the shore-shallow lacustrine environment.