The Quantitative Identification Method Of Slope Break Zone And Its Application In The Cretaceous In Chepaizi Area

The slope break belt has great effect on sedimentary and lithology in the slope area,especially in the steep slope area.It also controls the development of the lithologic-stratigraphic trap.The lowstand systems sandbodies and non-structural reservoirs developed in the slope break belt have become important targets for oil and gas exploration.Therefore,it is important to accurately identify the distribution range of slope break belt.By fine structure interpretation of the Cretaceous Qinghsuihe Formation,Hutubi Formation,Shengjinkou Formation and Paleogene Ziniquanzi Formation based on the 3D seismic data of the Chepaizi area in the Junggar Basin,this paper combine seismic and geology method to identify and analyze the slope break belt in the study area.Based on the previous studies,this paper puts forward the qualitative and quantitative identification method of slope break belt based on the trend surface theory,the seismic dip attribute and the slope theory.The mathematic surface model,dip logging,formation thickness contours and seismic geology profile are used to verify and analyze those methods.It uses the seismic attribute and seismic inversion technique to indentify and predict the sandbodies in the study area,and then analyze the relationship between the slope break belt and sandbodies,sedimentary facies and stratigraphic lithologic reservoirs.The result shows that the above three methods can effectively identify the distribution range of the slope break belt in the study area.The method based on the slope theory,with the highest accuracy,can quantify the geometric parameters of the slope break belt such as slope gradient,horizontal width and height difference.The Cretaceous strata in Chepaizi area of the Junggar Basin are wedge-shaped monoclinic structure which tilts NW-SE with complex fault system.The study area develop successional flexure slope break belt in Cretaceous period,and is main controlled by the deep large overthrust fault and the ancient Carboniferous salient.The slope break belt has a controlling effect on the sedimentary facies,sandbodies and non-structural oil and gas reservoirs in the study area.Therefore,the stratigraphic-lithologic traps made up of deltaic lowstand sandbodies in this area still have great potential for oil and gas exploration.