The Development Characteristic And The Prediction Of Favorable Zones Of Litho-stratigraphic Traps For Silurian In Tarim Basin

Litho-stratigraphic trap,as an important oil-gas group,has gradually attracted petroleum geologist attention.Practice on exploration presented that the exploration of litho-stratigraphic traps in Tarim Basin had been very important.Based on outcrops,drilling data and seismic data,this paper studied the features of the sequence stratigraphy of Silurian in Tarim Basin first.The sedimentary face types and Time-space distribution within the sequence stratigraphic framework was analysed as well.Then the types,formation condition and distribution law of the litho-stratigraphic traps were cited in this paper to predict its favorable horizon and distribution.Base on all the results above,it submitted two exploration targets with the 3D-seismic data and the seismic attributes and inversion technology.This paper has three peculiarities below:(1)By comprehensive analysis of the sedi-sequence,palaeogeomorphology and formation condition of litho-stratigraphic traps,it proposed that the litho-stratigraphic traps was multi-controlled by three elements:sedimentary face,sequence and palaeogeomorphology;(2)Two section of Lithology section can be identified in Kepingtage fomation in Tazhong North slope area:the Gray Mudstone Section and the Down Sandstone section.The Section of down-sandstone was an retrogradation sandbody formed by the controlling of palaeogeomorphology in the course of transgression.Litho-stratigraphic traps formed as Gray Mudstone deposited above Down Sandstone;(3)There are several under-water low uplifts asloping to Northwest developing in Tazhong area;the uplifts could be benefit for the developing of tidal flat face and the formations of channel filled-lithologic traps.This paper got several recognitions below:(1)Silurian can be divided into three third sequences that each third sequence was constituted by TST and HST,in which tidal flat,shoreland,shelf and delta faces developed;distribution characteristics of facies were descripted in six sedimentary maps.(2)Five types of traps:stratigraphic overlap trap,lens,updip pinchout,channel filled and unconformity barrier trap mainly developed in Kepingtage Formation of Silurian.Their formation and distribution were obviously controlled by eustasy,palaeogeomorphology and sedimentary face.It can be interpreted that several eustasy benefit to the formaton of reservoir and trap,palaeogeomorphology change leaded to the different sedimentary faces and all these differences benefit litho-stratigraphic traps;(3)Litho-stratigraphic traps always developed in the TST of 3th sequence.On the other hand,it likely developed tidal flat and shore controlled by slope and under-water low uplift unit in the plane;(4)Considering the effection of fault and uncomformity and the distribution law of litho-stratigraphic traps,the most benefit exploration area was in Mancan1-Yihe1-Badong2-Tangcan1-Tazhong34;(5)Basing on 3D-seismic data and the recognition to sedi-sequence and condition of oil&gas,some targets were submitted in the Ka1 3D and Shun1 3D area.