Sequence Stratigraphy Of The Nantun Formation In Bayan Hushu Sag Division And Analysis Of Reservoir Conditions

The predecessors divided the third-order sequence into the Nantun Formation of the Bayan Hushu Sag,and the division of the fourth-order sequence was not deep enough.This paper comprehensively uses logging,drilling,earthquake and other data,preferably the INPEFA logging and reversing technology method based on the theory of cyclic stratigraphy,systematically and deeply divides the third and fourth sequence of the Nantun Formation in Bayan Hushu Sag,and synthesizes it.The inflection point in the prediction error filtering analysis(INPEFA)curve can reflect the sequence interface of different levels,and the curve trend can also reflect the change of sedimentary cycle.The south segment can be divided into one third-order sequence by INPEFA technology.It is further divided into five fourth-order sequences;the second two-stage is divided into one three-level sequence,which is further divided into three four-level sequences,and the well-seismic combination is completed to complete the eight Nantun Formation main line and the well earthquake-geology Explain the section view.Under the guidance of sequence stratigraphy,the abundance,type and thermal evolution of organic matter in source rocks were studied in the study interval.It is concluded that the organic matter types of the source rocks of the Nantun Formation in Bayan Hushu Sag are well developed.It can be seen from the"A"analysis data of root and chloroform asphalt that the first and second sections of the Nantun Formation are basically I-II type,the source rock basically enters the mature threshold at about 1100m,and the mature layer is the top of the second section.The organic matter types of the study samples distributed in the western steep slope tectonic belt are poor,but the organic matter types of the source rocks of the Nantun Formation are well developed.In the horizontal direction,the section of the Nantun Formation of the Bayan Hushu Sag and the second layer of the Nantun Formation have the thickest mudstone.In the longitudinal direction,the second section of the Nantun Formation and the section of the Nantun Formation have reached the good~best source rock standard.Conduct seismic reservoir prediction research,conduct petrophysical statistics on the study area data,and then carry out seismic inversion to prepare for reservoir prediction.According to petrophysical statistics,the boundary line between mudstone and sandstone wave impedance is 7000g*m/(s*cm~3).At the same depth,the wave impedance is greater than the value of sandstone,which is less than the value of mudstone;The three-dimensional well wave impedance profile is obtained;the reservoir physical properties are analyzed from the longitudinal and lateral directions respectively.From the overall perspective,the physical properties of the second segment are better than those of the southern segment.The traps in the Bayan Hushu sag mainly consist of broken nose and fault block traps.The oil and gas generated in the sag migrates along the fault to the upward direction of the rock formation,and finally forms oil and gas reservoirs,forming the trap side of the reservoir.The fault is mainly dominated by lithologic closure.On the whole,the Bayan Hushu sag is developed in the southern part of the source rock,with high maturity,and the front row trap close to the sag is extremely favorable,while the South 2nd stage is limited due to poor maturity of the source rock and limited prospects for oil and gas exploration.