目前的物源方法一般局限在地质与地球化学方法上,如重矿物分析法、碎屑岩类分析法、同位素法、裂变径迹法等等.但这些方法存在较大的局限性,它们只能反映井上及井周围地层的物质特征.对于一个井少且井分布不均匀的地区,这些方法就不能准确判断物源方向或无法判断物源方向.地球物理方法在这种情况下就占据一定的优势,因为该方法得到的横向上的地层信息较连续.主要概述了如何利用地球物理方法中地震相、反演、地震属性分析方法来判断物源方向,并结合实例使用地震属性中的频谱分解方法分析某工区的物源方向.

The wide-spread sandstone in Xujiahe Fomation of the Upper Triassic,Sichuan Foreland Basin,is one of the most important exploration strata.With the exploration development of the gasfield,it needs to clarify the predominant factors that control the widespread sandstone developing to guide the further exploration and production. To elucidate the depositional mechanism and spacial arrangement of the the widespread sandstone,the sedimentary physical simulation method was adopted to transform the original geological conditions into physical model,on base of investigating the evolution of tectonic,ancient landform and sedimentary system,and so on.And the simulation parameters were taken into consideration and designed to study the mechanism of widespread sandstone through the simulation of flume experiment technology.Three provenances were designed in the experiment to incarnate the characteristics of sedimentary systems during different stages and at different locations under the multi-source conditions.Six intervals were simulated to playback the sedimentary characteristics,by conducting the experiment which was designed referring to principle of simulation and natrural model method.The main controlling factors of widespread sandstone were concluded,by designed such as simulation parameters,such as flow,sediment flux,gradient,subsidence and lake level et al.Some preliminary conclusions are obtained as follows： 1.Under the gradual slope conditions,it is in the shallow area-at the depth of 2.3 cm,slope of 4 that distributary channels migrated frequently,where the area water passed became larger gradually.And so did the area where sandbody deposited and was retransformd,which was benefit for widespread sandstone developing.The sandbodies were universally thin and homogeneous.And the width-thickness ratio of the deltas is grater than 98∶1. 2.In the experiment,when the flux was 4.35 l/s and sediment content was 9.5 g/s,the channels branched and sandbodies moved forward.While was 0.49 l/s and 0.4 g/s,single channel developed and sandbodies were eroded.So the flux and sediment content of different water consociation helped widespread sandstone development. 3.With tectonic subsidence and accommodation extending,the sand sediment developed to sandbodies of certain scale. 4.With frequent changes of the lake level,sandbodies of each stage expanded to different directions in the plane and overriding in vertical.Besides,the lobes combinated laterally,widespread sandstone was easily developed. 5.In the experiment,convergence of 3 sources showed explain of the development of widespread sandstone.During 6th depositional stage,the lake level rised in ascending order： 10cm-12cm-14cm-16 cm-18cm,when the sandbodies deposited continuously towards the source regions.When the lake level dropped from 18cm to 12cm,the accommodation decreased,the sediment carried by rivers deposited in low-lying location and former sandbodies were reformed obviously,which was benefit to widespread sandstone. In the depositional process,the channels bifurcated into distributary channels and lateral migrated continuously.The sandbody prograted and retrogradated vertically by fluctuation of lake level and assembled in horizontal and vertical direction.Then widespread sandstone developed.

The upper Triassic Xujiahe Formation in Sichuan Basin had the characteristics of wide distribution of sandbodies,big thickness of sediments,growth of multi-sources,big changes of the multi-source sediments and various periods of sediments.To represent the results of large scale of the sediments,a physical model was especially designed for the multi-sources in Xujiahe Formation.Because the features of different sources,different times and different positions were needed for simulation experiments,in the model design,3 sources were designed and six formations were simulated.Similitude principle combined with naturalness simulation principle was used for model design to present the real sedimentation characters.By using the similitude principle,the similitude correlation was established between the primary type and model for determining the boundary and designing the source features,settling the volume of flexible floor and the changes of the lake level.The hydrodynamic parameters were simulated for the experiment by naturalness simulation principle.The experimental parameters are repeatedly adjusted and validated by test-bed experiment and experiences,and the physical quantities required for experimental model are eventually determined.

The Late Triassic Western Sichuan Foreland Basin was the outcome that the fold-thrust belts developed in the front zone of orogenic belt thrust toward the Western Sichuan Area,it was due to the western edge of Yangtze plate occurring subduction to the west and colliding with the arc(land) land or another plate,it belonged to peripheral foreland basin.It was experienced complicated evolutionary process that the tectonic environment was transformed from extension to compression and deposited huge thickness of Xujiahe Formation that continental deposition was dominated,the unique sedimentary filling characteristics were established in the plane and in vertical direction.In the plane the difference of sharp subsidence caused by intensive Longmenshan thrust of orogenic belt and low amplitude steady subsidence of orogenic belt makes the differentiation of steep slope filling in the front of thrust belt and gently slope filling in Cratonic margin.And in the vertical direction,the structural movement has the episodic features alternating between active period and static period,the basin is filled with shore-shallow lake fine deposition of Member 1,3,5 of Xujiahe Formation and heavy-bedded and blanket sand of Member 2,4,6 of Xujiahe Formation.The alternated fillers of mudstone and sand are created by sandwich type source reservoir caprock.

Through the fine analysis of sedimentary facies,the microfacies proportion of different sand bodies is analyzed.The reservoirs in Beisanxi Area of Saertu Oilfield are divided into four reservoir structures:Type A and Type B,which are mainly distributary channel facies;Type C and Type D,which are mainly sheet sand of delta front.The geologic model is established using the geologic constrain modeling method.In a small layer for unit,the reserves of different microfacies are calculated and reserves distributions are analyzed,which shows that the reserves distribution of reservoir with different facies structure have different features and the reserves structures are different.On basis of traditional reserves estimation and considering the influence factors of facies structure on reserves control,this paper also considers that this method can directly represent the reserves of different genetic sand bodies and can provide a quantitative basis for analyzing the potentialities of different sand bodies.