Study On The Deep Structure And Gas Hydrate Prediction In The Shule Depression,South Qilian Mountains

Natural gas hydrate,commonly known as "combustible ice",is an ice-like crystalline material formed by water and methane molecules under low temperature and high pressure conditions,and usually occurs in submarine sediments and in permafrost.It is a new type of clean energy with good prospects for exploration.China,as the third largest frozen country,has a huge gas hydrate energy prospect.However,due to the lag in research on natural gas hydrates in China,it is still at an early stage.Since the successful drilling of hydrate cores in the frozen soil area of Qilian Mountains in 2008,the area has become one of the research hotspots.The study area is located in the Shule Sag,South Qilian Mountain.Due to the complex geological features and adverse weather conditions,the effective identification and prediction of the favorable gas reservoirs in the terrestrial area of the region still lacks a systematic and effective way of thinking and methods.Therefore,exploring and analyzing the geophysical anomaly response characteristics of gas hydrates in the permafrost region has important theoretical and reference values.In view of the complex geologic structure in the study area,the paper studies the restoration of the balance section through the well section in the study area.The mapped structural evolution section visually expresses the stratigraphic development of the study area and accurately examines the fine structural interpretation of the seismic data.This technique is used to analyze and summarize the research area,and provide the basis for the positive and negative work in the later period.In view of the characteristics of the hydrates in the study area,such as multi-attribute anomalies,this paper proposes a method for comprehensive verification of various geophysical technologies.Based on previous studies,this paper analyzes the hydrate accumulation characteristics of the area,and establishes a complex geological model based on the geological structure and well logging information in the study area.Combined with post-stack impedance inversion and multi-attribute techniques,the comprehensive prediction and verification of hydrate reservoirs are performed,and their geophysical response characteristics are analyzed and summarized.The detailed construction interpretation,post-stack impedance inversion,and comprehensive application of multi-attribute technologies have effectively reduced the problem of multi-solution of gas hydrate reservoirs in the terrestrial area,and greatly improved the prediction accuracy of reservoirs.This paper analyzes the hydrocarbon accumulation characteristics and geophysical response characteristics of the gas hydrate in the permafrost region,combining high-quality seismic data processing and structural interpretation.The use of post-stack impedance inversion comprehensive prediction and verification of the study area hydrate reservoir.It is believed that the basic geophysical response characteristics of natural gas hydrates in Shule depression area of South Qilian Mountains are characterized by velocity inversion,amplitude reflection blank,and abnormal seismic attributes.Secondly,the comprehensive burial depth of hydrate is determined on the isothermal plane or isobaric surface,and the distribution characteristics of hydrates are identified based on the amplitude,frequency,and dessert properties in the burial depth range of the hydrate.It provides an effective technical means and method for the identification of sensitive parameters of natural gas hydrates in the hydrates of this area and in other similar terrestrial frozen areas in China.