The eastern part of China refers to the vast area east of east longitude 1 12 and north of the Yangtze River. Among them are the famous Northeast Plain, North China Plain and parts of the middle and lower reaches of the Yangtze River, with a total area of about 2.5 million km2. There are many Mesozoic and Cenozoic sedimentary basins in eastern China, which are the main places for oil and gas exploration.
Because these Mesozoic and Cenozoic sedimentary basins are almost completely covered by the thick Quaternary (130 ~ 160 m), oil exploration has always relied on expensive seismic exploration methods. However, in recent years, with the introduction of remote sensing technology and its application practice in petroleum geology of Nanyang Basin, Zhoukou Basin, Subei Basin, Huanghua Depression and Liaohe Basin, remote sensing technology has a good geological interpretation effect and great application potential in petroleum exploration in a large area of Quaternary coverage, especially through appropriate image processing, combined with geological and geophysical data to explain deep geological structures and structures, which can achieve satisfactory results.
The concealed structure in Quaternary coverage area is indirect information obtained through the interpretation of micro-geomorphological characteristics, water distribution characteristics, soil moisture, vegetation community types and other related factors displayed by remote sensing images. Then, combined with the existing geophysical and geochemical data, the geological significance and attributes are judged to provide geological data for oil and gas exploration.
On the other hand, as a special geological body, under various geological effects, its hydrocarbons can penetrate through the dense overburden and penetrate into the surface in various ways, or be adsorbed by the soil to produce various physical and chemical effects, resulting in soil alteration and plant growth variation; Or hydrocarbon substances escape into the air, reach a certain concentration, and form mist floating above the oil and gas field under suitable climatic conditions such as temperature and humidity. Because this fog has a strong reflection on the solar electromagnetic radiation in the visible band, it forms a "shadow" bright area on the remote sensing image. Then these soil alteration zones, vegetation variation zones and "shadow" bright zones may indicate the existence of underground oil and gas reservoirs.
Second, remote sensing reveals underground geological information.
The fundamental task of petroleum remote sensing is to use the remote sensing data (data) obtained by airborne or spaceborne sensors to obtain images reflecting the comprehensive information of various ground objects through computer processing, establish various geological interpretation marks under the guidance of modern petroleum geology theory, and explain the possible ground effects of regional geological background, basin structure (including secondary structural belts and large-scale local structures) and oil and gas micro-leakage, and synthesize relevant information such as geophysical and geochemical exploration on the basis of field verification.
As far as the satellite remote sensing data (MSS or TM) used at present is concerned, it is difficult to obtain satisfactory geological interpretation results for the Quaternary large-scale coverage area and serious human landscape interference in eastern China. After years of exploration and research, it is an effective way and means to reveal the underground geological structure and structure by processing the new image with four main functions: linear stretching+histogram adjustment+local statistical enhancement+color gradation coloring. This is achieved by using MSS data on I2S 10 1 system. This new image has been applied in many oilfields in the east of China, and achieved good results.
Figure 1 Remote Sensing Interpretation of Gravity and Aeromagnetic Anomaly Superimposed Images and Annular Images in Nanyang-Biyang Depression.
1-linear image; 2- abnormal band sound; 3— Gravity isoline; 4- aeromagnetic isoline; 5— Special processing of the ring image displayed on the image; 6— Ring image displayed on the image after conventional stretching; 7— Known petroleum areas
Fig. 2 Geological Interpretation Map of Comprehensive Processing Image of Biyang Depression
Fig. 3 Geological Interpretation Map of Satellite Images in Dongpu Depression
1-ring image; 2- main fracture; 3- Secondary fracture; 4- hyperopia area; L- ring image related to basement uplift; A- ring image related to depression; R- ring image related to basalt; N-ring image related to modern sedimentation; O —— annular image related to known oil fields; Y-ring image for predicting oil.
(1) Example 1: Biyang Depression
Biyang Depression is a continental sedimentary depression formed in Late Mesozoic (K-R), with a total area of 4700km2 and a sedimentary thickness of 9000m, including 2000m in Cretaceous and 7000m in Tertiary. The surface of Biyang sag is covered by Quaternary, with a thickness of 100 m.. Biyang sag is a huge light-colored annular anomaly on the standard pseudo-color composite image, with dim tone and unclear geological information. After multifunctional combined image processing, the information content and color richness have been obviously improved (see plate ⅳ- 1). After interpretation, several annular structures are found, which are consistent with most local structures determined by geophysical methods (Figure 1). Especially r 1- 1-3, r1-9, r1-8, r 1-4 and r/kloc-0. More importantly, in the future exploration, two oil fields, such as Fuwan, were discovered in the east-west R 1- 12 prediction area.
Fig. 4 Geological interpretation map of combined processing of satellite images of Liaohe fault depression.
1- Pre-Cretaceous continuous outcrop distribution area; 2- Pre-Sinian latent uplift area; 3- Paleozoic and some Mesozoic basement distribution areas; 4- Slope or basement dominated by Mesozoic; 5- local uplift; 6- local depression; 7— obvious linear structure; 8— obvious linear structure; 9— Set the ring structure and number related to the oilfield; 10- lakes and water systems
(2) Example 2: Dongpu Depression
Dongpu Depression is a Mesozoic-Cenozoic tectonic basin with an area of about 3500km2, flat terrain and well-developed water system. On the MSS standard false color composite image, the image contrast is small and the color is monotonous. The flocculent shadow structure on the light background is only the reflection of the slightly inclined plain with the surface slope of 1: 2000 ~ 1: 6000. After multifunctional combined image processing, the single factor of the ground surface is changed, and the image presents a rich and subtle annular shadow structure under a light background (see plate ⅰ- 1). Compared with geological data, most of them are closely related to the convexity and concavity of basement and basalt or local structures at different depths. In particular, bright annular anomalies are often related to known oil fields. In 1985, the author made an oilfield prediction based on remote sensing research. Results Two tertiary oil fields (Figure 3) were discovered between the prediction area 1987- 1989, with reserves exceeding 20 million tons.
(3) Example 3: Liaohe Basin
The buried depth of Paleogene in Liaohe Basin is about 3000 ~ 4000 m, and the covering thickness of Neogene-Quaternary is 800 ~1500 m. The surface is flat, the water system is developed, and the surface conditions are extremely complicated, plus a large area of farmland and meadows. However, after multi-functional combination processing, the image can still reflect the basic morphology and changing characteristics of uplift structure in Liaohe Basin with different colors and colorful texture structure (see plate ⅵ-2). In particular, some buried hill belts in the western depression are also clearly reflected in the images, such as Shu Qi (R- 17) and Xinglongtai (R- 19) buried hill belts (Figure 4). Most of the linear structures interpreted by remote sensing have also been confirmed as hidden faults by drilling data, and some known oil fields have also been reflected in different degrees in the regional processing images. Therefore, under the premise of considering the geological structure background, we have predicted a number of new oil-bearing areas through the comparative analysis of image characteristics, among which the overseas river prediction area (Figure 4,0 ~18) has found oil fields in the later exploration and has been put into development. In addition, Kailu Basin in the periphery of Liaohe Basin and Subei Basin in Jiangsu Province have also achieved exciting results.
Of course, while emphasizing the use of multi-functional combined images to process the obtained information, we must never ignore the experiments of other processing methods and the comparative analysis and research of multi-temporal and multi-species images, so as to further develop and improve the remote sensing methods of petroleum geology.
Third, detect oil and gas information on the ground.
The surface detection of oil and gas information is an attempt to detect the abnormal characteristics of various surface geophysical and geochemical exploration fields produced by subtle oil and gas reservoirs. There are many articles and materials about it, so I won't go into details in this article. Now I just give an example of Biyang basin.
1985, in order to verify the results of remote sensing geological interpretation, soil adsorption of hydrocarbons and regional hydrochemical sampling analysis were carried out in Bichu sag. The results show that the content of adsorbed hydrocarbons in the oil-generating sag is obviously increased, and the anomalies of elements such as Hg and I, and the fluorescence and ultraviolet anomalies of aromatic hydrocarbons are also closely related to the distribution of oil fields (Figures 5 and 6), which are also consistent with the anomalies of remote sensing images in different degrees. Therefore, according to different geological and geographical backgrounds, the establishment of effective interpretation marks can make a useful contribution to the exploration of oil and gas information by remote sensing technology.
Fourth, the basic conclusion
The application of remote sensing technology in petroleum exploration is still very short, but the application research of more than ten years shows that remote sensing images can provide necessary information for the regional study of oil-bearing basins. Combining with various data, we can not only study the causes of the basins, but also further study the structural characteristics and spatial laws of the local structures of the basins. By choosing the corresponding image processing method, rich hidden geological information can be obtained, which can become reliable and practical geological data if verified by geophysical exploration and drilling data. Analogy analysis of remote sensing image features also has great application potential in oil and gas prediction. Remote sensing technology is fast and cheap, which can greatly save investment, shorten exploration period and improve exploration efficiency when used in oil exploration. This is a new technology worthy of active development.
Fig. 5 Isogram of hydrocarbon adsorbed by soil in Biyang Depression
The main components of hydrocarbons are C6-C9, with the highest content of 3957μg/g and the lowest content of 23 μ g/g; 38 Sampling points and number
Fig. 6 Distribution of hydrochemical anomalies in Biyang Depression
1-residual anomaly isoline of typical trend of organic components (cubic); 2—δ 13C CH sampling point and content (‰ pdb); 3— Comprehensive abnormal areas (zones) and their numbers; 4-Abnormal salt content
refer to
Ye Hefei, Cao Xiujuan. Application of remote sensing image in oil and gas exploration in Dongpu sag. See: Essays on New Theories, Methods and Technologies of Oil and Gas Exploration. Beijing: Ocean Press, 1989.
Wang Fuyin. Remote sensing study on oil and gas leakage in a certain place in eastern China. Remote sensing of land and resources, 1990, (4).
Yang Bailin. Spectral information of rocks and minerals and aerial subdivision infrared spectrum remote sensing prospecting. Remote sensing of land and resources, 1990, (3).