| Amu Darya Right Bank Block of eastern Turkmenistan, a long-narrow regionlocated between Amu River and Uzbekistan, is the source of natural gas of central Asiaand the headstream of the China-East Asia pipeline. The studied area, which acrossthree secondary structural units (including Chalzu terrace, Beshekent depression andsoutheast Gilsa slop), experienced multi-stages of structural evolution in the geologicalhistory, exhibits complex fracture types, and gas pool of this area distributed indifferent sedimentary belts possessed significant variations. The structural evolution,fault features and the key factors control the gas pools formation need further morestudies.Based on the well log strata correlation, seismic interpretation, this article studied thestrata relationship, fracture characteristics, structure evolution periods, the key factorsof gas pool formation and the like in Callovian-Oxfordian of Amu Darya Right BankBlock in Amu-Darya basin by the theory guidance of sedimentology, structural geologyand natural gas geology with the data from the logging, drilling cores and laboratoryanalysis.According to the results of logging features recognition, strata correlation andprecision seismic interpretation, the strata distribution variation and the fracturefeatures of Callovian-Oxfordian was emphatically analyzed, and this made the firmfoundation for the further studies of strata correlation, structural evolution perioddivision as well as gas pool formation. And through this study, three importantsearching development and innovations are obtained.①A theoretical promotion forthe mostly used traditional logging correlation of strata is bring forward, and proposedthe narrow sense logging stratigraphy, which can be the beneficial supplement to thetraditional strata correlation method such as sequence stratigraphy etc. Narrow senselogging stratigraphy, based on the principle of causality and binary rule of geologicalevolution history, consists of the logging combination features, relatively static and changeful characteristics, and the complete stratigraphic sequence. In practice, thenarrow sense logging stratigraphy includes4basic steps, distinguish the relative stableand variable logging features, establish a complete stratigraphy sequence, establishstandard sections and correlate strata of different regions.②Integrated the result ofseismic interpretation and salinity analysis, the isochronous stratigraphic relationshipof Callovian-Oxfordian in A and B region is constructed with the method of the Narrowsense logging stratigraphy. According to that, the phase change from the strata of XVm,XVp, XVac in A region to HA and HB in B region is recognized, and exploringlyconstructed the sedimentary model of high salinity carbonate.③Based on the seismicisochronous interface tracking and fine fracture interpretation,9seismic isochronoussurface from bottom to top are interpreted and the corresponding structure maps areconstructed successively, subsequently. According to the result of the3types and8sub-types fracture analysis, it is proposed that, the studied area mainly experienced4stages of structural evolution, which including the rifting stage from Permian toTriassic, Callovian-Oxfordian stage, Yanshanian stage and Himalayan stage. AndCallovian-Oxfordian stage is the trap embryo stage, Yanshanian stage is the trapformation stage and Himalaya stage is the trap reconstruction stage.④Through theintegrated study of stratigraphy, structure and fracture, and combined with the typicalgas polls anatomy of the studied area, it is concluded that structural evolution,fractures and the sedimentation are the main factors that control the formation of thegas pools of Amu Darya Right Bank Block. The structural-lithological trap of thesouth slop and the lithological trap in the center of B region should become significanttargets in the further deploy scheme of natural gas exploration. |
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