Study On Characteristic And Predicting Technology Of Igneous Rocks In Tazhong Area Of Tarim Basin

The igneous rocks is developed in Tazhong area. Scientifically studying and predictingthe igneous rocks is the basis for comprehensive petroleum evaluation and explorationplan. Based on a lot of information including drilling, logging, seismic and geologic data,etc and combining them together, using technologies and methods such as wellcalibration, seismic facies anlaysis, seismic attribute analysis, velocity analysis,petrophysical analysis, impedance inversion and forward modeling, etc., this papercomprehensively predicted the igenous rocks in Tazhong area. The lateral and verticaldistribution, variance regulation of interval velocity, attitude, lithology, petrophysicalresponse and forming phases of igneous rocks were analyzed. The geophysicalcharacteristic of igneous rocks was also studied. It is the first time to use a quantifiedforward modeling to study the influence of igneous rocks on its underlying structure inTazhong area, and a set of method to predict igneous rocks by geophysical techniquewere summarized. The prediction of igneous rocks is well matched with drilled result.The main results and understandings was briefly introduced as follows:①There were several phases of volcanic activity in Tazhong area. Four of themwere confirmed, which are Later Sinian to Early Cambrian, Later Cambrian to EarlyOrdovician, Later-Mid Ordovician and Early Permian. The largest scale volcanism wasoccurred in Early Permian.②In the studied area, the thickness and lithology of igneous rocks are different ineach formation from Sinian to Permian. They are mainly intrusive rocks in earlier periodand eruption rocks in mid-later period. Vertically, igeneous rocks and volcanic clasticrocks are interbedded frequently.Igneous rocks in Permian is thinning gradually from thenorthwest to southeast then pinch-out.③The influence of igneous rock on its underlying structure is controlled by severalfactors such as the shape, thickness, velocity of igneous rock and the velocity differencebetween igneous rocks and its wall rock.④In order to increase the reliability of igneous rock prediction by seismicinformation, the valid amplitude and frequency of seismic data should be kept during theprocessing,and the influence non-geological factors should be eliminated as more aspossible.⑤The prediction of igneous rock distribution in trap No.5 of Katake 1 area ismatched with the drilling result by Well Zhong-1, which encountered good oil and gasshows in Permian igeneus rock.⑥This study will have a positive significance for the oil and gas exploration inTazhong area.