| Jimusaer sag is located in the east of the Junggar Basin.It is bordered to the east by the Guxi uplift,Qitai uplift to the north,Fukang fault to the south and Beisantai uplift to west and its area is about 1278km~2.In recent years,the results of exploration show the main target is Wudonggou formation which is at the high point of the structure.So the Jimusaer sag is long-term in favorable directional zone of hydrecarbon migration and the exploration prospects of it is good.The study area is lack in structral trap but it is ease to form the lithologic trap because the Wudonggou formation overlaps the Guxi uplift from west to east.However, it is difficult to recognize this kind of trap,so how to search for the litologic trap is the urgent problem we should solve.This study develope the work that includes identification of Sequence boundary,analysis of sedimentary face, description of reservoir character, analysis of favorable sedimentary facies belts and so on by integrated application of seismic,log and geochemistry data. Main achieved cognitions are as follow:1) Based on the division drilling sequences and the reflect termination of seismic profiles in the study area,the Wutonggou formation is divided in several strata sequences,the whole Wutonggou group is divided into a 3rd-order sequences,two 4th-order sequences, and WuTongGou formation 1st section and 2sec section concurrently.LST and HST systems were developed in the WuTongGou formation , Occur in the LST system low fan and incised valley which were composed of large set of Conglomerate. In the Well sections, the sed sedimentary characteristics of LST system are very obivous in the JI7th well ;The transgressive system tract is mainly formed of braided delta and fan-delta which were composed of gray sandstone, pebbly sandstone and mudstone;The HST is composed of the gray mudstone, sandstone and sandy mudstone on the whole.At this point,the lake is subsidenced steadily ,because of the flat terrain,a large area of shallow water or deep lake facies developed,and fan delta system occur in some steep slope area.2) Through sequence analysis, made four stratigraphic correlation sections and made a comparative analysis of the four sections by using a few mouthfuls of typical wells in the study area.These sections reflect the sedimentary characteristics and sequence evolution.3) Through the study of sedimentary and reservoir, and combining with the 90°phase transformation technology, multiple attribute analysis technology and so on, Jimusaer sag was divided into three belts. I belt mainly developed unloading fan delta, Although its buried deep property medium, the reservoir storage conditions is better ,because it's far from the eastern slope erosion area ofJimusaer sag, and has better debris content.Ⅱ,Ⅲin the slope with better hydrodynamic conditions, combined with relatively shallow burial depth, so the physical conditions were better.4)Just Wutonggou formation overall, with the following rules: source from the south, In the South the reservoir conditions is better than the North ; affected by compaction,the area that higher than Ji17 borefild has good physical properties in Wutonggou formation; Internal development of small faults enabling vertical migration of oil and gas; Wutonggou group is cut Jurassic erosion, the reservoir storage conditions were better than the cut Paleogene erosion. |
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