Sequence-lithofacies Paleogeography And Sandbody Distribution Rule Of The2th Member Shanxi Formation In Yulin Gas Field, Ordos Basin

Erdos basin is one of Chinese "main resources of basin of West to East Gas Transmission", the current proven Daniudi, Yulin, Surig and other large oil and gas fields, Erdos basin area of about2.5×105km2. The Yulin gas field is located in the northeastern part of Erdos basin exploration and development potential of the upper Paleozoic gas field, about8500km2area. This gas field of Shanxi formation,lower Permian is coal-bearing clastic rock, from top to bottom is divided into P1s1and P1s2, the P1s2is the main gas production.In this thesis, sedimentology, high resolution sequence stratigraphy and lithofacies palaeogeography of the guide, the2th member of shanxi formation in the northeast of the Erdos Basin as the research object, combined with the sedimentary geological background, drilling core and well logging data, the combination of macro and micro, carrying out the system of2th member of Shanxi formation depositional system, the high resolution sequence stratigraphy, palaeogeography and sequence lithofacies study of sandbody distribution in detail. The following research achievements and progress:1.The2th meber of Shanxi formation of Yulin gas field belongs to Marine braided river delta sedimentary system, gas field in braided river delta plain subfacies belt, can identify the distributary channel, natural levee, crevasse splay, inter distributary bay and interdistributary swamp and flood plain microfacies, including distributary channel sand body with sand layer thickness is larger, better physical properties, the sand body in the vertical and longitudinal communicated on the characters, for the benefit of reservoir sand body.2. combined with previous studies, the drilling core, logging, seismic and analytical data results, using the theory of sequence stratigraphy of2th member of Shanxi formation in Yulin gas field,2member of Shanxi formation of the high resolution sequence stratigraphy study, the2th member of Shanxi formation is divided into1long term cycles, and further divided into2medium-term cycles,4short-term cycles, and the establishment of the2th member of Shanxi formation stratum sequence frame. Study on the characteristics of2th member of Shanxi formationdevelopment group, sequence interface characteristics.3.Comparison in the analysis of high resolution sequence stratigraphy and the sedimentary microfacies and sequence analysis, combined with the establishment of the marine facies, braided river delta sedimentary mode, the sequence-paleogeographic mapping, depicts the distributary channel sand bodies and plane distribution characteristics of Yulin gas field, and space-time evolution rule, provides the basis for2th member of shanxi formations of Yulin gas field, Prediction of oil and gas reservoir exploration evaluation and efficient development.