盆1井西凹陷东环带三工河组层序地层格架及沉积特征OA

Located in the central Junggar Basin,the eastern ring of the West Sag of Well Pen-1 is a significant tar-get for oil and gas exploration in China.However,controversies persist in terms of the sequence stratigraphic framework division of the Lower Jurassic Sangonghe Formation.Based on logging and core data,this paper adopts analytic methods including maximum entropy spectral analysis,prediction error filter analysis(PEFA),integrated prediction error filter analysis(INPEFA),cosine of instantaneous phase,and wavelet time-frequency analysis to process lithology-sensitive logging curves.As a result,curves such as the frequency trend,cosine of instantaneous phase,and wavelet coefficients at different scales as well as time-frequency chromatograms are ob-tained.Sequence boundaries of different orders are identified by analyzing trend inflection points of varying am-plitudes,oscillation characteristics of the obtained curves,and energy variations in the time-frequency chromato-grams.Single-well stratigraphic division is conducted on 53 drilled wells penetrating the Sangonghe Formation in the study area,and 28 of them are selected for cross-well sequence framework correlation analysis.Addition-ally,the sequence stratigraphic framework and sedimentary distribution characteristics of the second member of Sangonghe Formation(J1s2)and the third member of Sangonghe Formation(J1s3)are studied.The research re-sults indicate that J1s2 and J1s3 in the study area collectively constitute a third-order sequence,internally de-veloping three system tracts of the lowstand system tract(LST),transgressive system tract(TST),and high-stand system tract(HST).Furthermore,J1s2 can be divided into four fourth-order sequences.The depocenter of the study area exhibits migratory patterns,primarily distributed in the northwestern and northeastern parts,with the most significant depocenters located near the Z11 and QS4 wells.Finally,a high-precision sequence strati-graphic correlation framework for J1s2 and J1s3 is established,various sequences and sedimentary boundaries are identified,and their spatial sedimentary characteristics are clarified,thus laying a foundation for the detailed oil and gas exploration in the study area.