Technolog Research On Using Seismic Data To Predict Reservoir In The FuXian Project Of Oredos Base

The reservoir distribution and physical property of reservoir are thekey factors in the Fuxian exploration area of Ordos basin.Directed by theresults of foreward modeling, to analyze the wave form charateristic ofburied grooves on the Majiagou formation unconformity of the Paleozoicperiod, to analyze seismic attributions of the sand body in the pre –Paleozoic period and Mesozoic.Based on plenty of detected seismicattritutions, the sandstone distribution has been analyzed. By using sparsespike inversion and seismic charateristic inversion methods, all seismicprofiles in the subject haved been inversed. Mainly achievement asfollows:1.Early Paleozoic period gas reservoir is controlled by the tend ofburied grooves. There are lot of seismic reflection caused by the buriedgrooves They have follow characters: events pulleddown, round waveoccuring , return–wave ,enlarged event amplitude,number of the eventsbecoming more.The tend of the grooves in the area are NW-SE.2.Exist of the sand body enhances the seismic . A changing amplitudecharater show on the seismic profile,thee isolated sand body make thesandstone bottom event cut the downlying event.It causes seismic phaseand frequency chang. The river mouth sand bar show a strong energy onthe top of main sand body, the strong energy of the distributary channelsand is at te bottom of the sand body, meanwhile uplying event of thesand body has a low relief .3.The reflection amplitude of one sand layer changes with the sandthickness .The amplitude of Shan2 layer has something to do with thecoal bed. The thicker coal bed is, the stronge reflection amplitude. Thereare two possibilities about the poor reflection amplitude: no coal bed, orexisting thick gas sand.4.Because of the big overlap area between sandstone impedance andmudstone impedance ,the impedance cannot identify the sandstone andmudstone effectively. There is a better correclation between the Garmmarvalue and rock lithology.5.Predicted framework sandstone thickness and effective sandstonethickness have better correclation in the lower Shihezi formation.Both ofthem show same thicker sandstone area at the east and west sides, thinsandstone area is in the middle area. Fugu2 well area and Zhongfu2 wellarea and west area of the project with thicker effective sandstone arefavorable zones of lower Shihezi formatin.South of Fugu1 well area andZhongfu21 well area are favorable zones of the Shanxi formation.6.According to the results of the predicted Chang8 section of Yanchangformation which is the mainly objective section,the thicker frameworksandstone and effective sandstone distribute from south to middle area ofthe project. It indicates that there exit channel sand bodies in the southernproject. There exist three Chang8 effective sandstone belts in the east,middle, and west area respectively. It is favorable to form lithologicalreservoirs where permibility sandstone and non-permibility sandstoneinteractive exist on plan. Chang7 sandstone mainly distributes in thenorth and east of the project. The thicker framework sandstone andeffective sandstone distribution areas are consistent with the area ofvariable amplitude seismic facies. Fugu4 well area is target zone. Chang6sandstone is thicker in the most of project, but the framework sandstoneand effective sandstone mainly distribute in the west area of the project.