Sequence Stratigraphy And Sendimentary System Of Upper Jurassic To Lower Cretaceous In Papuan Basin

Abstract:The Papuan Basin underwent superimposition of onshore and offshore and was generated in the marginal Mesozoic and Cenozoic Australian plate. The basin is resulted from a secular evolution and ultimately the deposition thicknesses covers from2,000to6,000m where rich oil and gas resources have been found. This thesis is an analysis mainly on the Upper Jurassic and Lower Cretaceous in which possesses the mess of oil and gas.On the basis of the previous studies, this thesis is designed to make a systematic sequence devision on the Upper Jurassic to Lower Cretaceous in the Papua Basin with massive amount of data such as seismic, logging, drilling and so forth. This thesis is also designed to research the sedimentary system of the Imburu group, Toro group and Ieru group. The sequence stratigraphy model and sedimentary system mode in the Mesozoic basin were therefore established. The sand body constrained by the sequence stratigraphic framework from the Upper Jurassic to Lower Cretaceous was evaluated. Our studies have shown as follows:Eight type â…  third-order sequences were identified from upper Jurassic to Lower Cretaceous; The sequence pattern of the northern and southern edges of the basin was controlled by the sedimentary faults, the fastest growing faults is in the Cretaceous, while the shelf break in southeast continental is type â…  sequence pattern; Fluvial-alluvial systems, shore systems, delta systems and slope-basin systems were included in the Mesozoic, the fluvial-alluvial system and delta system were widely distributed in Jsq12sequence, while shore systems were the most widely developed in Ksql sequence; The thickest sandstone was developed in Ksql sequence while the widest in Jsq12sequence. The subtle traps could formed by LST sand in the deep water area, stratigraphic traps can be formed by TST sandstone in the shelf break, if covered directly by TST mudstones large-scale traps can be formed by HST sandstone. lacked of seal, the exploration potential of HST sandstone was lost in southeast, and the research extent of the LST and TST sandstone was still very poor.Controlled by the sequence stratigraphic framework and the relationship between the physical properties of sand and its relationship with Source-reservoir-seal combination were considered, the research found LST and TST had more exploration potential, the most favourable LST sand located in the deep basin, while TST sand was located above the shelf break, the southeast Fly platform in Jsq12period and the Central Fly platform in Jsq13period were the most favourable area in the region besides the Papuan fold belt.