Partial Geophysical Features Of Songliao Basin And Its Peripheral Typical Basins

Songliao Basin is an important geologic structural unit in the northeast part of China and one of the areas which have wealthy oil and gas. It has gestated Daqing oil field which is the biggest continental facies oil field of China. The special geological conditions have drawn many attentions of rocksies. The surrounding basins of Songliao are possessed of their own predominant location advantages. Along with massive oil and gas explorations, we have accumulated lots of data on geology, geophysics, geochemistry, geotherm, oil and gas cause of formation etc. These valuable research findings did very important work in a way of oil and gas explorations. But, the oil and gas reserves which have been proved up are reducing day to day. So, It has very important meanings to take more exploration in Songliao basin and its surrounding basins.The aims of oil and gas explorations are more and more complicated nowadays, such as complicated surface conditions and underground structures. So, it is necessary for us to use varieties of geophysical methods synthetically, so as to solve all of these problems above and get more comprehensive understanding on underground stuctures.Base on above reasons, the paper aims at Songliao basin and its surrounding typical basins and constructures By ways of geophysical methods such as gravity, electricity (espesialy MT) etc. The study is according as many geophysical lines'data, and refering to previous geologic and geophysical data about the Northeast of China. Then, The paper has study systematacially on Songliao basin, Dayangshu basin and its south depression, Yilan-Yitong basin and Tangyuan rift, Sunwu-Jiayin basin, Boli basin, Jixi Basin, Sanjiang basin and Hulin basin etc. It has got each basin's geophysical features such as gravity anomaly, basement wave forms, electrical stucture and so on and made primary perspective oil and gas predictions on the low density and low resistivity areas.Before studying the geophysical features of the aimed areas, it is necessary to introduce the main basic theories and methods that used in the paper. first of all, the paper introduces integrated geophysical methods, the the golden rules of integrated geophysical interpretions which name "one,two,three and many", the proceedings that needed to be absorbed much attentions and the methods which are used in this paper. Then, the paper introduces the MT methods by the numbers which is the most important method in the paper and espesially narrates remote reference MT technique and its application to the field experiment. The paper makes summarized study on low resistivity oil and gas reservois and provides theoretic foundations in a degree.The study fields are located Northeast of China, so before local geophysical studies it is nessary to introduce the geologic and geophysical field features of the whole northeast area by the numbers. Refering to gravity anomaly and aeromagnetic anomaly features of the northeast area, the paper introduces the gravity anomaly subareas and aeromagnetic anomaly subareas of the northeast area and base on these, introduces the characters of Moho fluctuating. As a result, we get understandings as a whole of geophysical field features of northeast area and its subareas. And these provide macroscopical tectonic frameworks and features for the further studying of its inner basins and constructures.The concrete study of this paper begins with Songliao basin. firstly, the paper studies the geology and constructure evolvements so as to provide geologic basis for the further geophysical studies. And then, base on the Manzhouli-Suifenhe geophysical section data, the paper analyses the velocity features of Songliao basin and along the tendency towards of Man-Sui section, the paper leads out the introductions of Dayangshu basin, which located away from the northwest edge of Songliao basin. Begining with the geology and construct units, the paper Analyses the constructional characters of Dayangshu basin based on the geophysical data such as gravity anomaly, aeromagnetic anomaly and seismic sections. By use of the data of a general geophysical survey line, which begins from the inner of Songliao basin, bypasses the Dayangshu depression and stops in the inner of Daxinganling, the paper studies the constructional relations of Songliao basin and Dayangshu basin. We analyse the partial geophysical features of the northwest boundary of the Songliao basin and the deep constructial relations between Dayangshu depression and it. all these analysises are based on the data and their inversion results of gravity and geoelectricity and the longitudinal wave velocity features of Man-Sui section. At last, we get the conclusion that the northwest boundary of Songliao basin has the same features of deep level velocities and electricity structure.Yilan-Yitong basin abuts on the Songliao basin at its west edges and it is a east-west directions, long and narrow and large Cenozoic rift valley basin. During the former oil and gas explorating, we have got evaluatings of it, that it is in possession of thick oil layers, high output,well characters of oil and gas, equipped with the combinations of forming, deposited and covered layers, well situated of oil layer. Yilan-Yitong basin has its well oil and gas foregrounds. By use of the data of a general geophysical survey line, which is throughout the Yilan-Yitong basin and bypasses Tangyuan rift depression, the paper studies general geophysical features, Division of fracture zones, constructrial subzones and modality of the base of the basin. The survey line is short, so we just take a typical study of the basin. But Tangyuan rift depression is the high light area of the study. As a result of the analysis on electrical structure of the line, the paper gets a primary future predict of oil and gas, aimed at the low destiny and resistivity below the 3000 km at Tangyuan rift depression.Sunwu-Jiayin basin deputs the northeast of Songliao basin, and it is almost east-west directions. By use of the gravity anomaly and aeromagnetic anomaly data, the paper studies the general geophysical features of the basin and the basin is divided into 2 parts by Xunke. The high light of study is 2 general geophysical survey lines that one of them is begin from Songliao basin inner and stop at the inner of Sunwu-Jiayin basin and the other is almost all lied in the Sunwu-Jiayin basin. the directions of the 2 lines is north-north-east and north-west-west. The former line is aimed at the constructial relations of the 2 basins and the latter line is aimed at the inner geophysical features of the Sunwu-Jiayin basin. By use of the gravity, electrical data and their inversion results of the 2 lines, the paper studies of the fracture Divisions, construct subareas and base fluctuant shapes of the 2 lines. And as a result of analysis of MT sections, the paper makes a detailed study on the electrical structure features of Songliao basin, Sunwu-Jiayin basin and Xiaoxinganling. At last, the paper makes primary oil and gas future predictions to some subareas of Sunwu-Jiayin basin.Boli basin, Jixi basin, Sanjiang basin and Hulin basin locate at the east direction of Yilan-Yitong basin. And this area is belonged to Northeast Asian Yuejinshan collage zone. This study is based on 5 MT sections which locate at 4 basins. Combined with the geologic and geophysical data of this area, the paper make a divisions of the areas which have the same electical structure features. And then, we analyse the subarea's electrical characters and get the following conclusions: Jiamusi massif is stable and almost symmetrical; Xingkai massif is relative stable and has no large changes; But Wadashan terrain is bad symmetrical and less stable. At last, the paper discusses the constructure features of the east boundry of Jiamusi massif, constructural features of Wandashan terrain collaging and the oil and gas characters of the 4 basins.In conclusion, the paper study the geophysical features of Songliao basin and its surrounding typical basins by used the study results of general geophysical survey lines. The paper gets some further understandings of deep constructral features of basins and constructral relations of basins and provids partial geophysical basis for carrying on new exploration fields and newly scanning oil and gas resources of basins. The paper gets some new understandings of basins and makes some primary oil and gas future predictions of some areas of basins, and we hope all these results can provide some directive meanings for the further oil and gas explorations in future.