To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the pa...To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the paper conducted the numerical simulation of pre-drainage gas in drillings along coal seam, studied the relationship of adsorption constants and permeability, gas pressure, and effective drainage radius of coal seams, and applied the approach to the layout of pre-drainage gas drillings in coal seams. The results show that the permeability of coal seams is on the gradual increase with time, which is divided into three sections according to the increase rate: the drainage time 0–30 d is the sharp increase section;30–220 d is the gradual increase section; and the time above 200 d is the stable section. The permeability of coal seams is in negative linear and positive exponent relation with volume adsorption constant VLand pressure adsorption constant PL, respectively. The effective drainage radius is in negative linear relation with VLand in positive exponent relation with PL. Compared with the former design scheme, the engineering quantity of drilling could be reduced by 25%.展开更多
选取祁连山天然气水合物钻探区DK-8井岩心样品中的砂岩,利用模拟气合成含天然气水合物砂岩样品,并进行电阻率及介电常数研究。砂岩样品在天然气水合物形成后电阻率明显增大。在温度震荡过程中,电阻率测量能检测到水合物或冰的二次形成...选取祁连山天然气水合物钻探区DK-8井岩心样品中的砂岩,利用模拟气合成含天然气水合物砂岩样品,并进行电阻率及介电常数研究。砂岩样品在天然气水合物形成后电阻率明显增大。在温度震荡过程中,电阻率测量能检测到水合物或冰的二次形成。在天然气水合物形成过程中,体系的介电常数变化规律复杂,在1 k Hz^100 k Hz频段内,含水合物岩石的介电常数存在频散特性,频率高于100 k Hz,频散特性变弱。从介电常数的实验结果来看,基于介电常数的电法勘探技术可用来定性分析含水合物储层,但很难定量研究储层的水合物饱和度。展开更多
基金Financial support for this work,provided by the National Natural Science Foundation of China(Nos.51327007,51104118 and51204134)Shaanxi Province Youth Science and Technology Star Project of China(2014KJXX69)
文摘To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the paper conducted the numerical simulation of pre-drainage gas in drillings along coal seam, studied the relationship of adsorption constants and permeability, gas pressure, and effective drainage radius of coal seams, and applied the approach to the layout of pre-drainage gas drillings in coal seams. The results show that the permeability of coal seams is on the gradual increase with time, which is divided into three sections according to the increase rate: the drainage time 0–30 d is the sharp increase section;30–220 d is the gradual increase section; and the time above 200 d is the stable section. The permeability of coal seams is in negative linear and positive exponent relation with volume adsorption constant VLand pressure adsorption constant PL, respectively. The effective drainage radius is in negative linear relation with VLand in positive exponent relation with PL. Compared with the former design scheme, the engineering quantity of drilling could be reduced by 25%.
文摘选取祁连山天然气水合物钻探区DK-8井岩心样品中的砂岩,利用模拟气合成含天然气水合物砂岩样品,并进行电阻率及介电常数研究。砂岩样品在天然气水合物形成后电阻率明显增大。在温度震荡过程中,电阻率测量能检测到水合物或冰的二次形成。在天然气水合物形成过程中,体系的介电常数变化规律复杂,在1 k Hz^100 k Hz频段内,含水合物岩石的介电常数存在频散特性,频率高于100 k Hz,频散特性变弱。从介电常数的实验结果来看,基于介电常数的电法勘探技术可用来定性分析含水合物储层,但很难定量研究储层的水合物饱和度。
