关键词: 大庆长垣, 姚家组, 自然伽马, Fischer图解, 湖平面变化

Abstract: This paper selects the typical coring well DQ-Z90 to study high frequency sequence stratigraphy of the Yaojia Formation of the Changyuan District, Daqing. Ninety-one ultra-short-term cycles, 32 short-term cycles, 9 mid-term cycles and 3 long-term cycles are identified, and the Fischer plot is drawn. Two other coring wells DQ-N1 and DQ-N2 neighboring DQ-Z90 are selected to calculate sedimentary cycles and thickness by using natural gamma logging data, linear regression and first-order differential. The Fischer plot is used to display lake level trends. The Fischer plots from the three wells can be compared and they are in accordance with that of Songke-1 well, reflecting the highfrequency lake level changes and long-term lake level trend. Thus it demonstrates the feasibility of the new method, and verifies the consistency of the Fischer plot.

Key words: Changyuan in Daqing, Yaojia Formation, natural gamma, Fischer plot, lake level change