Experimental Study On The Relevant Laws Of Oil Shale Pyrolysis-Permeability And Internal Structure Variation

With the fast development of the international economy, the demands for the energy of various countries are greater and greater, the regular petroleum resources can't already satisfy the fast growth of the oil demand. The oil shale, as a kind of comparatively ideal supplement and substitute petroleum energy, have already become the focal point of energy development of various countries. The oil shale reserves of our country occupy the second in the world, oil shales resources have broad use prospects, seeking effective and economic utilization route of oil shale, for relieving the imbalance between supply and demand of energy and promoting the development of society have great realistic meanings.This text take in-situ exploitation technology as the background, use experiment method, analyse and research the pyrolisis,permeability and variation of internal structure of oil shale, the following is research contents and conclusions:1) The weightlessness law of different temperature of oil shale is roughly divided into three stages:the first stage (room temperature～200℃): weightlessness of this stage mainly caused by moisture evaporation; the second stage (200～600℃):This stage is the main part of oil shale pyrolisis; the third stage (600～900℃):This stage is mainly shown as resolving of carbonate. Heating rate have certain influence on the weightless law of oil shale, initial temperature of heat decomposition maximum weight loss rates and peak temperature of weightless intensify ascendant trend with the improvement of heating rates and weightlessness of oil shale sample show as the downward trend with the improvement of heating rates. The difference of the moisture content due to the difference of weightless rates before 100℃, the greater the moisture content, it is the higher to intensify necessary energy, thus before 100℃, at the same time the temperature rising slower, shown as with the increase of moisture content TG curve moves to right.2) The porosity shows a tendency trend with the rising of temperature. Because of effect of oil shale pyrolysis, after oil gas material appear, a large number of hole cracks form in oil shale, at temperature section of 300～600℃porosity of oil shale has been increased by a wide margin, porosity of Daqing oil shale has increased by 24.84%, porosity of Yan'an oil shale has increased by 20.27%, this temperature section is the main stage of oil shale pyrolysis.3) Utilized CT experimental analyticl system, carried observe and analyze on course of structure variation of Daqing and Yan'an oil shale under different temperatures, obtain the law of the structure changed within the oil shale.The structure variation obviously takes place after 200℃within the oil shale, the impact on structure of oil shale of temperature mainly stems from two respects: one hand because every opposite sex of mineral particle thermal expansion causes out of shape and incongruously among the particles, on the other hand is oil shale pyrolysis results emerging course releases influence.4) Based on fractal theory oil shale internal structure change was researched. Regard the Daqing and Yan'an oil shale's gap area under different temperatures as the research object, and discuss the corresponding law between fractal dimension and internal structural change. Studies have suggested:200～600℃range, the gap distribution have strong self-similarity according with fractal law.5) Utilized the high-temperature rock-permeability testing machine devised by Taiyuan University of Technology was used to test the changes in permeability at different temperatures and gas pressure in the in-situ stress state. Study show:with changes in temperature Daqing and Yan'an oil shale's permeability rate have a critical temperature, the permeability rate firstly decreases and then increases according to the critical temperature as demarcation point. On the other hand, Daqing oil shale's permeability rate present decreasing trend and Yan'an oil shale's permeability rate present the state of fluctuation with the rising gas pressure.