准噶尔盆地盆地春光区块沙湾组S2-3准层序组沉积体系

发布时间：2018-11-08 20:01

【摘要】：车排子凸起新近系油气具有“层浅、优质、高产”等特征,具有很大油气勘探前景。然而,由于该区勘探程度总体还较低、岩性油气圈闭的成藏条件非常复杂,单独运用“亮点”模式无法解决该区勘探问题,特别是沙二段地层岩性,其埋深达到1600m为其“亮点”门限,故出现早期排2、排8井突破较大,后期排204、208井落空的现象。究其原因,主要是对目的层段砂体分布不明、沉积体系认识不清、无法落实圈闭位置等。针对上述问题,本文在前人研究基础上,综合应用钻井和地震资料,首先通过对早中新统沙湾组的层序地层结构分析,建立沙二段层序地层格架样式;然后选择S2-3准层序组为研究对象,通过典型钻井剖面的速度分析和波形分析,建立砂体识别标志;在此基础上,开展S2-3砂体的地震扫描解释,再通过砂体边界分析圈定砂体,展示S2-3砂体平面分布;最后,根据砂体的剖面结构特征(如前积构型)、平面形态、组合特征的综合分析标定水流方向,进而进行地震相和沉积相分析,认识三角洲—湖相沉积体系。主要进展与认识概括为以下5个方面:(1)通过沙湾组层序地层学分析,将沙湾组划分为3个三级层序,发现这3个层序基本对应前人的沙一段、沙二段和沙三段岩性地层单元划分。(2)沙湾组的层序地层结构及相分布分析表明,SQ2层序发育于沙湾组2级层序的湖进时段,即湖盆快速扩张期,欠补偿沉积造成沉积期的水体开阔且较深,这是S2-3准层序组发育于浅湖、半深湖和深湖环境的主要原因。(3)S2-3砂层组砂体扫描解释结果显示,该砂层组主要发育河道砂、河口坝、席状砂、叠覆扇砂。(4)水体体系分析结果表明,物源主要来自北北西向,三角洲内发育六个分支河道,这一认识进一步证实了徐国强等早期推断。(5)S2-3沉积体系研究表明,靠近北部隆起带发育三角洲沉积体,在前三角洲斜坡和浅湖环境缺乏砂体堆积,而在欠补偿沉积的工区南缘发育深水扇沉积体,从而形成大型湖盆缓坡带的三角洲—深水扇沉积体系。大型湖盆的快速湖进及欠补偿沉积是形成这种复杂沉积体系的主要原因。
[Abstract]:The Neogene oil and gas in the Chepeizi uplift has the characteristics of "shallow formation, good quality and high yield", and has great prospects for oil and gas exploration. However, because the exploration degree in this area is still relatively low, and the conditions of reservoir formation in lithologic oil and gas traps are very complex, the application of "bright spot" model alone cannot solve the exploration problems in this area, especially the lithology of the formation of the second member of the Shahejie formation. Its burying depth of 1600m is the "bright spot" threshold, so the phenomenon of early drainage 2, well 8 breaking through, and late well 204208 falling out. The main reasons are that the distribution of sand bodies in the target formation is not clear, the sedimentary system is not clear, and the trap location is unable to be implemented. In view of the above problems, based on the previous studies, this paper synthetically applies drilling and seismic data, firstly through the sequence stratigraphic analysis of the early Miocene Shawan formation, the sequence stratigraphic framework style of the second member of the Shahejie formation is established. Then the S2-3 quasequence group is selected as the research object, and the sand body identification mark is established through velocity analysis and waveform analysis of typical drilling profile. On this basis, the seismic scanning interpretation of the S2-3 sand body is carried out, and then the sand body is delineated by the boundary analysis of the sand body, and the plane distribution of the S2-3 sand body is displayed. Finally, the flow direction is calibrated according to the comprehensive analysis of the profile structural characteristics (such as progradation configuration), plane morphology and assemblage characteristics of the sand body, and then the seismic and sedimentary facies are analyzed, and the delta-lacustrine sedimentary system is recognized. The main progress and understanding are summarized as follows: (1) through sequence stratigraphy analysis of Shawan formation, Shawan formation is divided into three third-order sequences. (2) the sequence stratigraphic structure and facies distribution of the Shawan formation show that the SQ2 sequence developed in the lacustrine stage of the second order sequence of the Shawan formation, that is, the rapid expansion period of the lake basin. The water body of the sedimentary period is open and deep due to uncompensated deposition, which is the main reason that the S2-3 quasequence group developed in shallow lake, semi-deep lake and deep lake environment. (3) the result of S2-3 sand body scanning interpretation shows that the S2-3 sequence formation developed in shallow lake, semi-deep lake and deep lacustrine environment. The sand formation mainly develops channel sand, estuarine bar, sheet sand and overlying fan sand. (4) the results of water system analysis show that the source mainly comes from NNW, and six branch channels are developed in the delta. This understanding further confirmed Xu Guoqiang's early inference. (5) the study of S2-3 sedimentary system shows that delta sedimentary bodies are developed near the northern uplift zone, and there is a lack of sandbody accumulation in the pre-delta slope and shallow lake environment. Deep-water fan sedimentary bodies are developed in the southern margin of undercompensated depositional area, thus forming deltaic deep-water fan sedimentary system in the gentle slope zone of large lake basin. The rapid lacustrine movement and undercompensated deposition of the large lake basin are the main reasons for the formation of this complex sedimentary system.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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