The Research For Provenance Systems And Characteristics Of Sedimentary And Reservoir In Yingcheng Formation Of Shiwu Oilfield In Lishu Fault Depression

Shiwu Oilfield in Lishu fault Depression, located in the southeast of Songliao basin, has developed into a composite basin of fault depression superposition since Late Jurassic. And Shiwu Oilfield, in the center of the basin, is one of the richest oil and gas zone. In this paper, on the basis of core, logging, and a lot of analysis data, using sedimentary theories and methods as a guide, combined with mathematic theory of statistics, conducts a study of provenance Systems and sedimentary characteristics of Yingcheng Formation in Shiwu Oilfield.Through the methods of cluster analysis, clastic particles component, heavy minerals, the percentages of glutenite and dipmeter, carrying out a comprehensive analysis of provenance systems of Yingcheng Formation with the character of multi-source deposition in Shiwu Oilfield leads to a perspective that there are three depositional source systems, which are North Slope provenance, east Slope provenance and northwest provenance. And rock type is mainly igneous rock in the North Slope source Area. Rock types of the eastern slope source area are mainly magmatic rocks and metamorphic rocks. In Northwest source area rock types are mainly sedimentary and igneous rocks.Clastic grains from three directions gather in the study area, where the distribution extent of sediments from north slope and northwest are borader.In this study area, it mainly developed fan delta, braided river delta and lake sedimentary system types: fan delta forming in the early sedimentary period of Yingcheng Formation, distributing in the northern part and the eastern slope of the basin, is made up of sand bodies such as underwater distributary channel, mouth bar and sheet sand, which are current deposits and gravity flow deposits like mud flow. Braided river delta developing in the whole basin in the mid and late of the Yingcheng Formation, also has distributary channel and mouth bar and sheet sand microfacies, however, because of some factors leading to unstable deposition, such as terrain slope relief and frequent lake level change, sand distribution of braided river delta is relatively wider and thinner. Sedimentation of Lake face is mainly composed of the depositon of shore-shallow lake and deep lake. Shore-shallow lake is characterized with thin sand mud interbed, with bio-drilling construction; Deep lake and semi- deep lake have the feature of a large section of dark gray, black shale or of the argillaceous sandstoneShiwu Oilfield in Lishu fault depression, controled by multi-source, developed several sedimentary types. And in each deposition period, Provenance Systems and Sedimentary Characteristics have the strong inheritance, forming a sedimentation pattern of mixed-source deposition, differences in sources, development with inheritance.