The Architecture Of Meandering River Sand Body And Distribution Of Remaining Oil Of P1 Formation In The Development Area Of Northern Saertu

The study shows that 25-35 % remaining oil is preserved in the reservoir sandbodies for the reason of heterogeneity. Effected by architecture structure , the remaining oil is mainly distributed in some place of sandbodies. The most important thing is to make sure how the architecture structure influences heterogeneity. So the research on the architecture elements of a sandbody which is controlled by dense well pattern is very important.The article has set up sequence stratigraphy framework in P12 oil layer of the third team of the west second district in the north of Daqing Oilfield. Bounded by regional water flood surfaces, 3 4th order sequence have been recognized in this paper. The 4th order sequence is corresponded to P1-1,P1-2 and P1-3 segment respectively. On the base of the 4th order sequence framework, the deposit microfacies have been recognized, such as main stream channel , abandoned channel ,inter-chnnel lithosomic body combining the change of sand thickness to associate deposit microfacies in the surface. P1-2 is the characteristic of high bending meandering river sediment of delta plain which is combinding with river channel, abandoned channel, crevasse splay, crevasse channel ,nature levee and flood plain and so on. On the base of the microfacies analysis we aimed at main stream channel sand using the genesis configuration of sand contribute by Maill identify 3th 4th 5th order surface ,and the 5th order surface is channel fill composite sand boundary ,and the 4th surface is the boundary of between side store up of point bar in meandering river,and the 3th order surface is point bar accretion unit.The 4th boundary has very important sense to the reservoir heterogeneity and remaining oil distribution, so it is necessary to characterize the 4th surface ant its interior architecture.(the 4th surface could be continuously traced between 2 to 3 wells, which character is low angle, the bottom is 2°-3°,the middle and upper part is 3°-5°,which angle is postpone and the extend length of 4th surface is between 50-200m).By means of the certain of 4th surface air space spread out area and the angle and the distribution of abandoned channel, the visualization pattern of meandering river of P1-2 has been established, which could display the abandonment of river channel and the phenomenon of point bar elementary side store up. The meandering river apparently migrated twice in the study area, from the southeastern to the western.Finally ,by multidisciplinary analysis of the form of microfacies type ,the thickness distribution of sandbody ,the shape of sandbody and permeability variation, the 4th surface corresponds theⅡ,Ⅲinterbed which control the aeolotropy of the reservoir,the remaining oil distribute along the abandoned channel or under the 4th surface ,and the barrier bed which is separated by abandoned channel is favor place to look for remaining oil .