The Application Of The Geogas Measurement In Buried Fracture

Concealed faults is an important basis for the evaluation the crustal stability of geological environment and exploration of content resources, especially the active fault structure has a great significance to the construction, water conservancy and hydropower construction. Great Bend area is located in the Brahmaputra River survey area, the region is not only rich in energy and mineral resources, but also the most abundant water resources in watersheds. However, as the region is located in the Brahmaputra suture belt intense tectonic movement, many faults, combined alpine valley landforms are widely developed. Quaternary cover deep, insidious cause fracture study in the region has brought great difficulty to become the region of the construction and planning constraints. Thus, the buried fault detection and study area for water conservancy and hydropower project siting, energy and mineral exploration, infrastructure construction and other very important significance.The research is funded by the National Natural Science Fund Project: concealed geological bodies and the ground breaking of the gas field study(project number: 41074094); National Hydropower Engineering Consulting Group Chengdu Survey and Design Institute Topic: the study of fractured fault structure in the Brahmaputra River Milin Jiedi- dangga,Bingding- duosong, Lilong fracture. With the study of the geological and structural features of the work area, the comprehensive research achievements of predecessors, we carry out gas and radon meansure in Tibet mili and linzi area, find out whether there is Jidi-dangga and Zangbajuezu fracture, detect and demonstrate those buried faults, analysis the characteristics and distribution of gas anomalies above buried faults, explore the gas field to determine blind fault activity.This paper firstly describes the search for buried fault related technologies and features, then elaborate geogas principle and in looking for broken applications, combined with relevant geological survey. According to the specific condition of diffrent concealed fault, in the two test areas we lay 12 survey lines, which include 7 lines in Linzhi survey area 5 survey lines in Sejila survey area. Gas measurements were obtained to 374 and measuring points, 374 groups of data analysis, each set of 39 kinds of element data radon measurements were obtained to 19 measurement points. Based on the measured data processing and analysis, referring to the results of geological survey division of the presence of abnormal Multiple geogas element region, using multivariate statistical analysis of multivariate statistical analysis tools for anomalous areas and the use of fuzzy discriminating against blind fault activity intensity Comparative analysis.Finally, the following results:1. It exists a variety of elements to gas anomalies in the vertically above the buried fault fracture zone, showing elements of "group" distribution characteristics. Combination gas anomaly over the in different ruptures has the similar characteristics. Some trace elements(REE, Y, Rb, U) and rock-forming elements(Cr, Mn, Zn) and other concealed above the suspected fracture have obvious abnormalities high value, which has a good indicationt on the buried faultat some level.2. According to analyzing the gas radon measurements data of the two survey areas, and combining with the geological survey, we initially identified the presence of abnormal cross-sectional PM01, PM02, PM04 outlier ground which is the location of Jidi-dangga Concealed fault. The presence of PM12 exception, PM14 outlier in Milling Sejila sectional survey area is likely to reveal Zangbajuezu fault and its branches through the location. Applying geogas measurement to concealed faults bed area are feasible and practical application.3. By the means of cluster analysis, trace elements and REE classification multivariate statistical analysis of geogas elements in the abnormal area, it reveals elements of multivariate statistical anomalies combination of features.4. Comparative analysis of the different fracture abnormal contrast of geogas, the use of fuzzy identification method discussing the activity of Jidi-daga fault, obtained the weak fault activity characteristics of the fault and indicate that the geogas abnormal contrast can can reflect strength of the fault. So the abnormal contrast was positively correlated with the fault activity.