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Comprehensive utilization of outcrop herein , logging, seismic and core data to study the Ordos Basin important including the gas bit Shanxi group Xiashihezi , and obtained the following understanding : 1 , according to lithological characteristics and different phase ( sub - micro- phase ) deposition logging response characteristics to determine the river delta , lacustrine 3 types of sedimentary facies , riverbed deposition, levee subfacies River diffuse sub -phase , delta plain , delta front , prodelta subfacies and 15 microfacies the logging phase mode Fig. 2, SQ8-SQ10 period as the main delta depositional system . SQ11-SQ12 , due to the differences between north and south and down, dipping basin pattern formation of the North Longnan , river sedimentation significantly strengthen the river system and delta systems coexist . 3 , the Ordos Basin SQ8 period of water into the lake shoreline moved northward , to SQ9 period , began a large-scale water receded , the sand body migration significantly to the lake basin . This process continues until the SQ12, the lake area is shrinking . By single well to even the well logging division identified SQ8-SQ12 deposition period , fluvial and delta phase space boundaries , and clearly the spatial distribution of the various periods of the main sand body . 5, during the deposition of the Ordos Basin SQ8-SQ12 there is more than one direction provenance . The northern source supply is dominant. The state the northern basin 4-5 Antiquities source was almost parallel from north to south distribution . There are also secondary source in the south of the basin and the eastern , the formation of smaller deltaic sediments . 6, SQ8-SQ12 period, the river - delta system is a deposition of shallow water , the lake basin transformation of the role of weak , strong fluvial depositional systems . And extends far from the plane, distributary channel development . Delta facies underwater distributary channel can extend very far into the lake basin , up to 300 km , the sand within the body into the lake basin .
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