The Study Of Palaeozoic Sequence Stratigraphic Characters Of Abei-Shunbei Area In Tarim Basin

The research area lies in the west of Northeast depression in Tarim basin, mostlyincluding Awati and Shuntuoguole fault depression, and a part of Shaya doming,whose area is about 30000km2.Based on the classical sequence stratigraphy theory, the cycle sequencestratigraphy method was applied to study the high resolution sequence stratigraphy.On the basis of the framework of high resolution chronostratigraphic sequence, byanalyzing the drill and seismic data, the type and lateral distribution pattern ofsedimentary facies of the research area is studied. The paper draws some conclusionsas follows:1. By analyzing the well and seismic data, the divisional precept of highresolution sequence stratigraphy is concluded.According to the analysis of high-resolution sequence stratigraphy of well andseism, the sequence boundary of well and seismic section was built. The research areacan be divided into 12 third-order sequences by identifying the well base level cycleand seismic reflection configuration, such as onlap, truncation and so on.2. Through the seismic-lithofacies analysis, it shows 3 kinds of seismic faciescharacteristics in the research area.Three kinds of seismic facies characteristics were found through theseismic-lithofacies analysis in the research are for the first time: â‘ High amplitudecontinuous facies (high energy and low energy sedment alternations);â‘¡Alterableamplitude discontinuous facies, which indicates the change of channel sand bodiesthickness in horizontal direction. â‘¢Low amplitude facies, formed above highamplitude or between high amplitude continuous facies or blank reflection, whichindicates the close or single deposit with sand (high energy) or mud (low energy).3. The high resolution sequence stratigraphy of the research area was analyzed,and the framework of chronostratigraphic sequence was built.The sequence stratigraphy unit in the research area show the basic feature: LSTdevelop not as good as TST and HST. Under the base level and sediment sourcecombined action, it has the characters as follow: thick sand body was deposited in theLST, but with a little crossrange extension;in the TST, sand body was less than in theLST and had a good crossrange extension;because of the bad condition ofpreservation, the sand body seldom existed and had a bad crossrange extension.4. On the basis of the framework of high resolution sequence stratigraphy, thearticle systematically studied the sedimentary faciesIn virtue of analysis of well logging facies, seismic facies and intervalvelocity-lithological prediction, the type and distribution of sedimentary facies werestudied. These results show: during Cambrian-Ordovician period, it mostly develop aset of carbonate rock sedimentary system, there are different distribution between theeast and west of Luntai area;a series of continental-source clastic sedimentary systemdeveloped during Silurian-Devonian period, in the mass, it belongs to deep watertrough mare basin and onshore environment;during Carboniferous-Permian period , aset of basalt was mostly deposited, which was continental facies and onshore-shallowsea sedimentary system.5. Through analyzing the assemblage of resource, reservoir and seal rocks, thefavorable zone was predicted.Although boring result of well Shun 8 showed the shadow of the oil explorationprospect of Donghe sand, relatively, the geologic setting of Donghe sand was also thebest in the research area. Donghe sand formation has the better reservoir propertycondition, and the predominant assemblage of resource, reservoir and seal rocks. Thisformation located on the regional unconformity, and was propitious to oil and gasmigration. All of these show the significance of Donghe sand exploration.