Study On The High-resolution Sequence Stratigraphy Of Quaternary In Sanhu Area Of Chaidam Basin

Sanhu-Chaidong area is located in the eastern part of Qaidam Basin. There are about 60000km2 effective exploration area and five biological gas field have been found such as Sebei biological gas field, Tainan biological gas field. Tainan gas field was found in 1988. There was no breakthrough in other areas except the Tertiary of Yikeyawuru structure in the regional exploration. There are only 18.7% developed reserves which has been found. High-resolution sequence stratigraphy is the basis of all geological work, the establishment of stratigraphic framework is the basis of sedimentary facies analysis, forecasting and favorable sandbank search for subtle reservoirs. Therefore, high-resolution sequence stratigraphy study is important to the Quaternary of Sanhu-Chaidong area.In this paper, regarding the classical theory of sequence stratigraphy and Cross’s the cyclic sequence stratigraphy analysis as a guide, making full use of drilling, core, outcrop, analysis of laboratory data, conventional logging, palaeontological and seismic data in the study area to achieve comprehensive study and high-resolution sequence stratigraphy division on single-well. based on high-resolution sequence stratigraphic division more than 100 wells, a number of six sequence boundaries ( SB1, SB2, SB3, SB4, SB5, SB6), 5 sequences (SQ1, SQ2, SQ3, SQ4, SQ5) in Qigequan groups (Q1+2) are identified. Border sequences correspond to rock-layers, which are K13, K10, K7, K5, K3 and K1 respectively, flooding surface generally correspond to the K11, K9, K6, K4, K2.According to the VSP calibration of 6 wells and synthetic records of 34 wells, the correlation of wells and seismic data.based on the identification of contact relationship of the seismic axis, seismic sequence stratigraphy interpretation of the 50 seismic lines are finished and six sequence boundary and five flooding surfaces which have good match with drilling sequence boundary are identified.Integrating the analyses of drilling and seismic sequence stratigraphy,the conclusion can be stated as follows:①The thickness center of all 5 sequences which developed in the Quaternary of Sanhu-Chaidong are located in the southern part of Tainan area, and the sedimentary center transferred from west to east.②the corresponding relationship about rock-layers of Sebei, Senan, Tainan, Tuofengshan and Taijinaier , Yikeyawuru are K1 ~ K1, K3 ~ K2, K4 ~ K3, K9 ~ K4, K10 ~ K5, K13 ~ K6, the corresponding relationship about rock-layers of Yanhu are K4 ~ K1 / 2, K7 ~ K8, K12 ~ K9, K13 ~ K10.