| 鸡西盆地主力煤层水可动性及其孔渗控制 |
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| 引用本文： | 周文宇,王小明,曾凡桂,党正,朱冲,陈文文,王志壮,涂明恺.鸡西盆地主力煤层水可动性及其孔渗控制[J].地质科技通报,2021,40(3):124-131. |
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| 作者姓名： | 周文宇 王小明 曾凡桂 党正 朱冲 陈文文 王志壮 涂明恺 |
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| 基金项目： | 国家自然科学基金项目U1910204国家自然科学基金项目41972184国家自然科学基金项目41973077中国地质大学（武汉）学科杰出人才基金项目102-162301192664 |
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| 摘 要： | 水可动性是影响煤层气产出的重要因素，分析孔渗对水可动性的作用对鸡西盆地煤层气开发具有重要意义。以鸡西盆地不同矿区主力煤层为研究对象，开展了低场核磁共振（NMR）及渗透率实验，同时，结合称重测定煤样含水饱和度的方法，分析了煤层孔渗特征对煤中水可动性的影响。结果表明:①研究区煤样中吸附孔较为发育，平均占比为58.36%；渗流孔和裂隙发育程度相当，平均占比分别为21.23%和20.41%，且两者之间连通性较好；②确定了煤样达到束缚水状态的离心力为1.38 MPa，此压力下煤中可排出半径约0.1 μm半开放或开放孔隙中的可动水。煤样可动水饱和度为27.84%~60.87%，平均值37.86%；束缚水饱和度为39.13%~72.16%，平均值62.14%，可动水含量相对束缚水含量较低。随着离心压力的增加，可动水首先沿着大裂隙流动，随后经过渗流孔流出，束缚水主要存在于吸附孔中，需要克服较大的毛细管阻力，难以流动；③尽管煤样变质程度相近，但其内部水的可动性及赋存状态存在明显差异，这可能是造成同一区块不同煤层气井气水产出差异的原因之一；④研究区煤中半径>1 000 nm段孔喉越发育、煤岩渗透率越大，煤的可动水饱和度越高，水在其中越容易流出；煤中半径0~100 nm段孔喉越发育，煤的可动水饱和度越低，水在其中被束缚而难以流动。
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| 关 键 词： | 煤层气 低场核磁共振 可动水饱和度 孔渗特征 鸡西盆地 |
| 收稿时间： | 2020-07-06 |
Water mobility of the main coal seam and its control of porosity and permeability in Jixi Basin |
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| Abstract: | Water mobility is an important factor affecting the production of coalbed methane. It is of great significance to analyze the effect of porosity and permeability on water mobility for the development of coalbed methane in Jixi Basin. In order to analyze the influence of porosity and permeability of coal reservoir on the water mobility, we performed low field NMR, permeability and water saturation experiments on the main coal seams of different mining areas in Jixi Basin.The results show that: ①Adsorption pores are relatively developed and the average proportion is 58.36%, while the seepage pores and fractures are similarly developed, with the average proportion of 21.23% and 20.41%, respectively.The seepage pores and fracture are well connected; ②The centrifugal force that makes the studied coal seam reach the bound water state is 1.38 MPa, under which the movable water can be discharged from half-open or open pores with a radius of more than 0.1 μm.By which the movable water saturation is 27.84%-60.87%, with an average of 37.86%; the irreducible water saturation is higher which is calculated as 39.13%-72.16%(av.62.14%).With the increase of pressure, the movable water flows first along the fracture, and then flows out through the seepage pores, while the irreducible water mainly existing in the adsorption pores is difficult to flow because of the large capillary resistance during centrifugation; ③There are obvious differences in water mobility and occurrence in coal samples with similar metamorphic degree, which may be one of the reasons for the difference of water and gas production in different block's CBM wells; ④The movable water in the study area is easy to flow out from coals with higher movable water saturation, greater permeability and more developed pore throat of more than 1 000 nm, but the water is difficult to flow out from coals with lower movable water saturation and more developed pore throat of 0-100 nm in which water is trapped. |
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