【作者】 刘炎昊；

【导师】 张小东；

【作者基本信息】 河南理工大学 ， 地质资源与地质工程， 2010， 硕士

【摘要】 基于以往对不同煤级煤储层物性及煤层气运移机理的研究成果,结合不同煤级煤的孔裂隙形态观测和孔隙结构参数测试结果,研究了高煤级煤储层孔、裂隙性,吸附、解吸特征,研究发现:高煤级煤的微孔含量较高,孔比表面积较大,压汞测得的孔隙中值半径和孔隙度较小;相对于低煤级煤,高煤级煤内的孔隙具有显著的定向性,但孔隙连通性较差,多为半封闭孔。孔隙形态、结构参数的变化规律,反映了煤化程度增高的过程,也是煤体内微孔含量增大,大孔含量减少,孔隙定向性增大的过程。进一步研究发现,高煤级煤的裂隙系统发育不均衡,外生裂隙较发育,内生及显微裂隙发育稀少,中间缺失次级裂隙的过渡。高煤级煤吸附性总体上要大于中、低煤级煤,但相应地造成气体解吸的困难性。以沁水盆地为例,探讨了高煤级煤储层条件下,煤层气排采过程中气体的运移过程及扩散、渗流的动态演化规律,构建了适于研究区的煤层气开采过程中气体扩散、渗流模型。研究认为:高煤级煤气藏含气性好,但相对解吸速率低,解吸效率不高,开发难度较大;煤层气排采过程中,孔隙内气体的扩散模式是一个动态变化过程,随着压力的改变,同一孔径范围内会相应经历不同的扩散模式。而由于高煤级煤特有的孔隙属性,Knudsen型扩散非常微弱,过渡型扩散贯穿于排采的整个过程,Fick型扩散主要发生排采降压初期,且在小孔径范围内的扩散速率总体要高于低煤级煤,在大孔径范围内则与之相反;高煤级煤的渗流通道发育不协调,渗流速率有一个快速增大的过程,但总体上仍较低煤级煤低,排采阶段受控于有效应力及煤基质自调节效应,区内储层渗透率呈现规律性变化。更多还原

【Abstract】 Based on the physical properties of coal reservoirs of different ranks and the gas migration mechanism of coal-bed research results, combine the test results of the pore fracture morphology observation and pore structure parameters of different ranks coal, this paper through research of reservoir pores and cranny property, adsorption and desorption characteristics of high-rank coal, the results show that: the micropore content increases gradually with the deepening of coalification degree, but the macropore content displayed contrary trend, the transitional and meso pore content changed slightly; High rank coal pore specific surface area is also greater than low rank coal, but the porosity and average pore radius are letter; The micropore distribute densely and directivity in high rank coal, however, the pore connectivity is worse and the semi-closed pore is in the majority. The change law of pore morphology and structure parameters show the increase process of coalification degree, that is the process of micropore content in coal increased, the macropore content decreased and the pore directionality increased. Further study found that the development is not balanced in the pore fracture system of high rank coal, which the exogenous pore fracture is more developed, endogenous and microstructure part is scarce, and the secondary pore fracture is lack. Adsorbability of high rank coal is greater than the middle and low rank coal as the whole, but increased the difficulty of gas desorption accordingly.This paper use Qinshui basin as an example to explore the evolution law of gas migration, diffusion and seepage in the discharge and mining process of coal bed gas with the conditions of high rank coal reservoirs, and form the gas diffusion and seepage model fit the research area. Study holds that: the gas-bearing property of gas reservoir is good in high rank coal, but relative desorption rate and desorption efficiency is low that difficult to develop; the gas diffusion model of inner pore is a dynamic changing process which changes diffusion model in the same pore size with the change of pressure. Due to the specific pore properties of high rank coal, Knudsen diffusion model is less, Transitional diffusion model throughout the entire discharge and mining process , Fick diffusion model mainly occurs in the beginning period of depressurization, and the diffusion rate in the small pore size is higher than the low rank coal, but the contrary in the large pore size. The development of seepage channels in high rank coal is out of line which seepage rate there is a rapidly growing process, but is still lower than low rank coal in general. In the mining stage it is controlled by the effective stress and self-regulating effect of coal matrix, the permeability of reservoir showed regular changes.更多还原