Development And Application On In-situ Geochemical Detection Technology Of Methane Concentration In Seawater

Gas hydrate is a potential clean energy, and the cage-like compound is formed from methane and water molecules under conditions of low temperature and high pressure. It is estimated that marine gas hydrates accounts for the hydrate resources total about 90%. Therefore, marine gas hydrate exploration technology research and development is very important on development of marine energy resources.Traditional oil and gas resources geochemical exploration methods, which used in marine gas hydrate exploration, has many disadvantages, such as difficult for sampling, high cost, long analysis-cycle, much deviation and so on, and its application is limited. Seawater concentration of methane in-situ survey technology is a new geochemical real-time detection method, with a small, continuous and rapid analysis, etc., to provide a new means of geochemical exploration for the discovery of the gas hydrate zone. Over the past decade, foreign progress a series of methane sensors, represented by the METS, with the use of optical, electrochemical, biology means to achieve the purpose of the in-situ detection. Chinese scientists have do some work on development of the technology, but mainly on Raman spectroscopy. The work is still on the stage of laboratory theoretical research or prototype testing, and cannot meet the needs of the marine environment and resources investigation.Against this background, the National 863 Program "In-situ geochemical detection system of marine gas hydrate" is aim at developing a new method to detect the methane and other hydrocarbon concentration of seawater in-situ. My paper is about the related work as the following.1) The systematic study of the domestic and international ocean in situ hydrocarbon indicators detection technology. Collecting a lot of data and summarizing the basic researches on the methane concentration of seawater in-situ survey technology all over the world. Having an in-depth understanding of the technology trends, and design ideas established on this basis, completion of the framework and the technical design of the developing system.2) Completed a combination of the four key technologies design and machine installation and joint commissioning of the developing system. The four key technologies are:reduced voltage of seawater and steady flow, rapid quantitative separation of seawater and quantification of the injector, light hydrocarbon geochemical testing by sensors and signal process, in-situ operations in deep sea and high pressure seal of the developing system. Doing lots of performance testing work on each part of the key components, and develop a system of methane concentration in-situ detecting in seawater with independent intellectual property rights.3) To participate in two sea trials of the developed system. The data results showed that ours test data are coincide with the all the original data of the same sea area, and are reliable. The developed system is expected to provide a favorable technical means for marine geochemical surveys.4) After two sea trials, summing up the practical experience of the sea trials, analysis and the problems of the developed system. Comparing with the similar foreign products and putting forward some corresponding recommendations to further improve the development of the system.