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The Geophysical Evidences Of The Structural Characteristics In The Northern And Eastern Areas Of North Harbin In Songliao Basin And The Analysis Of The Oil & Gas Structural Conditions

Posted on:2009-10-27Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y F HuFull Text:PDF
GTID:1100360245463469Subject:Earth Exploration and Information Technology
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With the rapid development of science and technology in the world, there are evident progresses in the theories of the petroleum geology and geophysics, which promote oil and gas exploration in the field of exploration targets increasingly complex circumstances continuing to make new discoveries and breakthroughs and achieve great economic benefits. Songliao Basin is an important oil-producing area in China, the fruitful results in the oil and gas reserves has been achieved in the south of the Binzhou railway in the north of Songliao Basin, but the situation of the North Harbin area in the north of Songliao Basin is very different. The North Harbin area has been become an important area for exploration to succeed with the reduced oil and gas resources in the old exploration regions. Because of its especial tectonic location and rich oil and gas resources, the Songliao Basin has become one of the areas of the geological workers concerned, the much concern is on the South Harbin area of Songliao Basin, but the concern on the North Harbin area is relatively less.In the nearly 50 years of the exploration process on the North Harbin area, the pre-work is all isolated study in a small area, large area integrated explanation has not existed, and the exploration degree is also low. With the abundance of exploration data, the development of geological and geophysical theories and the exploration technology, which provide the necessary conditions for the geological conditions and distribution rule in the formation of deep oil and gas. To this point we selected the northern and eastern North Harbin area in-depth study as the breakthrough and provided reference of oil and gas exploration for deep stratum in the entire Songliao Basin and similar international basins.Compared to single seismic research, we use a number of gravity and magnetic data to study the fault system in Songliao Basin, and provide a basis for further determining the distribution of fault system. There are decades of basement rifts in North Harbin area, which are important on the framework structure of top layer and oil and gas concentrating. Most faults are in NNE and NE direction.The seismic reflection layer of T5 corresponds the faulted sequence at the bottom (at the end of Basin interface) reflection. The bedrocks of the mess reflection exist under the seismic reflection layer of T5, and the sedimentary rocks or volcanic rocks exist on the seismic reflection layer of T5. The region is divided into two parts, bedrock raised areas (faulted strata missing regions) and the fault zones. In the raised areas, the bedrocks embed relative shallow, areas of ups and downs are large, has dome-shaped, the deep depression areas are smaller, mostly are residue faulted. In the faulted zones, the bedrocks embed relative deep, and the faulted are developed. The local structures on the reflective layer of T4 mainly reflect the local structural characteristics in the deep northern Songliao Basin. These local structures mainly developed and distributed in the late Jurassic-early Cretaceous faulted basins and the fringe regions around the faulted areas and the deep depressions. The reflective layer of T4 is sporadic distribution on the whole, almost distribute the whole region, but there are relatively concentrated developed areas. The distribution of the partial structures is basically NW and NE-NNE directions, but the former is more.The generation mechanisms of Songliao Basin are discussed further, the former researches are emphasis that the united functions of the Western Asia Ocean and West Pacific tectonic domain on the Songliao Basin, but through the research of this area, we find that Mongolia-Okhotsk tectonic domain has a very important function on the research of growing mechanism in the Songliao Basin in addition to the above two tectonic domains. The geological and paleomagnetic data indicated that the ancient Okhotsk ocean consisting of the northern part of Heilongjiang and the eastern part of Mongolia closed from west to east since Permian, and in the eastern part completed closure in the Early Cretaceous. The closure of the ocean had a considerable impact on the tectonic evolution of the Northern and Northeastern China located on it's southeast area.Compared with the single small-scale and isolated research, through the integrated and united interpretation on the research area, we can gained the more comprehensive research results. We use two seismic profiles and Vp distribution characteristics to analyze regional tectonic characteristics and evolution rules on the northern and eastern areas of North Harbin. Through the integrated and united interpretation on the research area, we found that there were two groups of inverse faults roughly distributed in NE direction in the northern and eastern areas of North Harbin, which broke through several layers, the groups of reverse faults often formed the local anticlinal structures, and might be beneficial hydrocarbon accumulation belts. Integrated the previous research work, we did the further research on deep faulted geological structure and evolution, the bedrock conditions and the forming dynamic background in the northern and eastern areas of North Harbin, the faulted of Lindian, Suihua and Beian had been considered the beneficial oil and gas accumulation zones.The precision is not enough through the two above profiles describing the features of sedimentary layers in Songliao Basin, but it has a certain credibility on qualitative account of the deep-seated shapes. The local deep study had been processed in Songliao Basin, and there also had some scholars predicting the deep oil and gas prospects in Songliao Basin. In contrast, using two long profiles from a regional point to analyze distributions of the deep stratum and discuss the relationship of oil and gas, it obviously has a more comprehensive understanding. Several major faulted in Songliao Basin almost exist the performance of faulted"concave"or"ancient basins", and in larger scale. Integrating these conditions, good hydrocarbon prospects had been considered in the deep layers of Songliao Basin. Intensifying the deep oil and gas exploration work has been considered to be necessary. Despite Vp distributed profiles had large approximation (that is, tectonic map of T5 had different accuracy), but the performance of macroscopical consistent could be used as a kind of evidences for deep depressions.The evaluation of oil and gas prospects in the northern and eastern areas of North Harbin has different nature from the southern part of Songliao basin, the sedimentary layers of depression are shallow in the northern and eastern areas of North Harbin, the account of generating oil and gas is less, can not be compared with the north part of Songliao Basin, the depth of faulted in the northern and eastern areas of North Harbin is similar to the depth of depression in the north part of Songliao Basin. The above geological facts suggest that the faulted and the depression period can not be separated in the oil and gas exploration of the northern and eastern areas of North Harbin. We can affirm that gas exploration in the northern and eastern areas of North Harbin is the overall exploration and the faulted period is more important. The faulted sequence in the northern and eastern areas of North Harbin and the overlying depression sequence belong to two sequences forming by different period of basins, and we should treat differently. Based on the exploration actuality of Songliao Basin, the depression sequence should be looked for oil mainly, and the faulted sequence for gas mainly."Concave in the apophysis"within the deep fault and the groups of inverse faults in the mid-shallow layers are the important areas of the gas in deep layers and the mid-shallow oil and gas exploration in the northern and eastern areas of North Harbin.
Keywords/Search Tags:in the northern and eastern areas of North Harbin, tectonic characters, seismic long profiles and the distributions of Vp, Mongolia-Okhotsk Sea tectonic domain, the groups of inverse fault, the oil and gas accumulated condition
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