Research On Sequence Stratigraphy Of Damoguaihe Group In The South Of Wuerxun Depression

Guided by the theories of sequence stratigraphy, structural geology, sedimentology and petroleum geology, using seismic data, borehole log, logging curves and cores, the sequence framework have been built, detailed research and analysis on sedimentary evolution, discriminate distribution of sand body and lithologic trap, carry on analysis for source, reservoir and cap rock, at last explore the prospect areas.Combined seismic data, well logging data, cores with chemical examination data, Damoguaihe group is a whole super sequence, it develops lowstand system tracts(LST) , transgressive system tracts(TST) and highstand system trarcts(HST). Damoguaihe group is divided into twelve fourth-order sequences: the first sequence (Dâ… 1) is the stage of braided river delta, comparable shallow lake and fan delta deposition of LST period; The second and third (Dâ… 2 , Dâ… 3 )sequences are the stages of braided river comparable deep lake and fan delta deposition of TST period. The fourth and fifth ((Dâ… 4 , Dâ… 5) sequences are the stages of meandering river delta, comparable deep lake braided river delta facies of early stage of HST period. The sixth-ninth (Dâ…¡1-Dâ…¡4) sequences are the stages of meandering river delta, comparable shallow lake braided river delta facies of middle stage of HST period. The tenth-twelveth (Dâ…¡5-Dâ…¡7) sequences are the stages of anastomosed stream delta, shallow lake braided river delta of the end stages of HST period. Sandstone is well developed with a higher sand-land ratio in the stages of LST, TST and middle stage of HST, while sand is not well developed in the rest of the two stages.The quality of hydrocarbon source rocks in Damoguaihe group is mainly bad-middle class, lack of hydrocarbon generate potential, oil mainly comes from the dark shale affected by segment one of Nantun Group. Oil migration experiences vertical and lateral movement, which is controlled by oil sources faults and lensoid body. From bottom to top Damoguaihe group develops three reservoir and capping sets and five prospect areas.