The Stratigraphic Sequence Research Of The Deep Formations Of Gulong-Changjiaweizi Fault Depression

This paper made sequence stratigraphy research in Gulong-Changjiaweizi fault deep formation area base on seismic, logging and well drilling data by the theory of sequence stratigraphy. The target strata studied in this paper include Huoshiling Formation, Shahezi Formation, Yingcheng Formation and Denglouku Formation. Of the studied target strata, this paper focuses the main research objective on the strata of Denglouku Formation, and also makes a groping research into the volcanic rock strata of the first segment of Yingcheng Formation.On the basis of carefully analyzing and referring the research fruits, by means of the study on the seismic data, logging data and drilling data, the author divides the target strata into four super-sequence. It is believed that the interface of each formation of the deep strata in the studied area is a super-sequence boundary, and accordingly each formation forms a super-sequence. Meanwhile it is also deemed that the strata of Denglouku formation in studied area developed Deng-2 Segment, Deng-3 Segment and Deng-4 Segment, and according to the characteristics of their boundaries, the strata of Denglouku Formation can be further divided into three sequences. Based on the above cognitions, an isochronous stratigraphic framework of the deep strata in studied area is built by means of tracing and correlating the well-tie seismic sections and of combining the well data and seismic data.Based on this cognition, the author analyzes the planar distribution features of volcanic lithofacies, on the premise of analyzing the evolution of sedimentary facies and sedimentary environment for the strata of Denglouku Formation inside the isochronous stratigraphic framework, this paper predicts the distribution of reservoir for each segment of Shahezi Formation strata by using various geophysical attributes. According to the analysis and the study on the seismic, logging and drilling data of the volcanic rocks from the first member of Yingcheng Formation, the author thinks the lithofacies types of the volcanic rocks in the studied region mainly include volcanic channels facies, eruptive facies, effusive eruption facies and volcanic-sedimentary rock facies. It is deemed that the structural subsidence is the main factor of controlling the development of stratigraphic sequence during the faulting stage, while the climate change is the leading factor of controlling the development of stratigraphic sequence during the depression period.At last, the favorable exploration zones in the studied area are pointed out by making an integrative consideration of various ingredients such as source rocks, reservoir rocks, cap rocks and traps.