Research On Several Key Technologies Of Sediment Thermal Conductivity Meter

Submarine geothermal research is critical to the comprehensive evaluation of the marine oil and gas resources. Combining with the knowledge of the basin evolution, it can help us to understand the temperature history of hydrocarbon source beds, even the organic matter maturehistory------which is important on the exploration of the marine oil and nature gas. Submarinegeothermal research is also important for the accurate evaluation and prediction of the natural gas hydrate resources. It consists of the measurement and calculation of the submarine temperature, the sediment thermal conductivity and the geothermal gradient, et al.This work is focus on the multi-channel measurement technology of the sediment thermal conductivity. The theory of line source method is adopted because it is one of the simple heat flow models and has been tested having high testing efficiency. This method is based on two-dimensional unsteady heat conduction's plane radial heat flow model, and the hardware is designed using a single-probe continued heating methodThe technology of the multi-channel measurement of seafloor sediment thermal conductivity includes the high precision and sensitivity environment temperature detection, the structure of the measuring probe, the control and the stimulation of the heat impulse, the high-precision measurement technology of temperature and the thermal conductivity SAM algorithm.The environment temperature detection technology is realized on the basis of the temperature balance between the sensor (thermistor) and the testing system. For the high-precision temperature measurement, the Agilent34401A is employed as the resistance measuring instruments of the thermistor with high temperature sensitivity, and the multi-channel measurement is realized based on one-chip computer module. The interpolation algorithm is utilized in the upper computer to achieve high precision and resolution values of the temperature by reading the resistance of the thermistor. The programming language is SCPI language.Heat impulse control and stimulation is realized by controlling the current of the controllable constant-current-source module to heat Kama wire. The current can be controlled in the area of 30mA-900mA and the stability can achieve 0.1 percent. The multi-channel excitation is realized on the basis of one-chip computer module.The measuring probe is made of small-caliber thin-walled steel pipe by encapsulating heating wire and thermistor internally so as to achieve simultaneous heating and temperature measurement.Thermal conductivity SAM algorithm takes the line source method boundary conditions into account and makes use of computer technology to eliminate unqualified solution to ensure the reliability of the test data.Multi-channel thermal conductivity meter has been tested with three samples, fine sand, submarine sediment and standards quartz. In the test, the meter can realize eight-channel measurement and achieve the self-inspection precision of 7% as well as the mutual precision of 15%. The results proved the meter can meet the requirement of the practice of the submarine sediment thermal conductivity measurement. Comparing with the foreign TK04 thermal conductivity meter, our meter has several advantages, such as the multi -channel and high efficiency.Our work is involved in the "the eleventh five-year plan" 863 natural gas hydrate special project "natural gas hydrate heat flow in situ detection technology" and the "the eleventh five-year plan"863 exploration project "the multi-channel measurement technology of the sediment thermal conductivity",. The paper may also provide research foundation of further development of the thermal conductivity measurement.