Comprehensive Research By Seismic And Geology Of The Silurian-devonian In Western Bachu Of Tarim Basin

West Bachu region of tarim basin can be divided into three blocks, Bashituo, Yasongdiand Maola which is an important secondary unit in central uplift belts in tarim basin.According to oil and gas exploration results in recent years, it is indicated that Devoniandoghetang and kezierta formation have some promising prospects. Due to the priorexploration horizons being carboniferous and Permian systems, main production formationin the study region are the Lower Permian nanxia formation, the upper carboniferousxiaohaizi formation and the upper carbonate rock section and the lower sandstone section oflower carboniferous system. Resulting from limit investigation into siliurian-devoniansystem strata, sedimentary facies, lithofacies, paleogeography and reservoir macroscopicdistribution characteristics reservoir physical properties、types of reservoir space andmicrostructure characteristics can not be fully recognized,this situation affects thedeployment of oil and gas exploration.This paper takes the siliurian-devonian system strata as a study object, a virtual3Dwork area has been built up by using2D lines. Directed by stratigraphy, SequenceStratigraphy, petroleum geology and Seismic Exploration Theory, a primary recognitionabout sequence stratigraphy characteristics in this region has been accomplished inaccordance with drilling, logging and Seismic data. Compared with the results oflogging-seismic inversion and drilling data, a comprehensive research on the inversion isdone; seismic facies are classified in terms of waveform similarity and seismic attributes;physical properties are predicted based on inversion results and logging data; A syntheticprediction of reservoir physical properties of the study object is completed with the results mentioned above.In light of the research results, the researched area is comprised of1megasequence,2supersequence and6three-level sequence. Most Kepingtage formation seismic facies are ofcomparatively continuous and subparallel reflection configuration with medium amplitude.If the configuration is detected in the west part of the researched area, it reflects that thesedimentary environment is of high energy. If the configuration is detected in the east part ofthe researched area, it reflects the sedimentary environment is of low energy. Tataaiertageformation seismic facies are of continuous or comparatively continuous subparallelreflection configuration with medium amplitude in general, which reflects sedimentaryenvironment of low energy. As for Yimugantawu formation, the amplitudes range from lowto medium, the facies are either discontinuous or comparatively continuous, the internalreflection configuration is subparallel or granitoid. This kind of facies generally reflectthat the sedimentary environment of this area ranges from low energy to medium energy. Asfor Keziertage and Donghetang formation, the amplitudes range from low to medium and thefacies are discontinuous, which reflects that the that the sedimentary environment is of highenergy.On the basis of seismic facies and stratigraphic correlation，it can be regarded that thematerial source may totally come from western，but it varied in different periods.In siluriansystem， material source approximately came from northwestward in Kepingtageformation，the source mainly came from southwest in Tataaiertage formation，but inYimugantawu formation，the source mainly came from westward. In devonian system，material source may came from westward or southeast in Keziertage formation，but inDonghetang formation material source may came from westward.Using log binding seismic inverting technique is used in virtual3D work area to carryout the inversion. on the basis of Seismic inversion，the Distribution Law of sand body canbe listed as following：the sand body of Kepingtage formation, the overall performance isthat thick in eastern and gradually thinning trend to the west,； but in Tataaiertageformation，the thickest sand body in northwestward and it is thicker in southwest andNortheast；sand body is mainly in the north and reduce to the surrounding in Yimugantawu formation；the sand body also well developed in jia1well and kang1well in Keziertageformation，but in Donghetang formation the sand body is mainly distributed in central andsouthern.According to the comprehensive research on reservoir property of Keziertage andDonghetang formation, it is implied that both of them have a good quality, especially thosedistributed in the western and central part. In general, reservoir property of Keziertageformation is superior to that of Donghetang formation.