祁连山冻土区天然气水合物储层岩石热物性实验研究

doi:10.19657/j.geoscience.1000-8527.2018.02.17

摘要/Abstract

摘要：

采用扫描电镜测试了祁连山冻土区天然气水合物储层泥岩和砂岩微观结构。在显微镜下观察到,泥岩由微小均匀的片状多边形块体构成,这种微观结构使得泥岩中水合物以浸染状赋存;而砂岩内部存在分散状孔隙,砂岩中水合物为孔隙赋存。采用瞬变平面热源法测试了含甲烷水合物储层岩石的导热系数和热扩散率。在温度为-9.41~9.41 ℃时,干泥岩导热系数为0.577~0.853 W·m^-1·K^-1,含甲烷水合物储层泥岩导热系数为0.704~1.050 W·m^-1·K^-1。在温度为-8.11~9.28 ℃时,干砂岩导热系数为0.828~1.271 W·m^-1·K^-1,含甲烷水合物储层砂岩导热系数为3.850~4.555 W·m^-1·K^-1。在温度为-9.41~9.41 ℃时,干泥岩热扩散率为0.712~0.894 mm²·s^-1,含甲烷水合物储层泥岩热扩散率为0.792~1.006 mm²·s^-1,干砂岩热扩散率为1.198~1.674 mm²·s^-1,含甲烷水合物储层砂岩热扩散率为1.403~1.769 mm²·s^-1。测试数据表明,对于孔隙型水合物,测定导热系数是一种较好的辨识水合物存在的辅助手段。

关键词: 天然气水合物, 导热系数, 热扩散, 微观结构, 泥岩, 砂岩

Abstract:

In this paper, the reservoir microstructures of mudstone and sandstone from Qilian Mountain permafrost were tested by electron microscopy. Under the microscope, the mudstone is composed of tiny and uniform flaky polygonal blocks, so that the hydrate immerses in the mudstone. The sandstone has dispersed pores inside, thus the hydrate exists in the sandstone by pore-type filling. The thermal conductivity and thermal diffusi-vity of reservoirs bearing methane hydrate were measured by transient plane heat source method. At the temperature range of about -9.41 to 9.41 ℃, the thermal conductivities of the dried mudstone and the mudstone bearing methane hydrate are 0.577-0.853 W·m^-1·K^-1 and 0.704-1.050 W·m^-1·K^-1, respectively. At the temperature range of about -8.11 to 9.28 ℃, the dried sandstone and the sandstone bearing methane hydrate have thermal conductivity of 0.828-1.271 W·m^-1·K^-1 and 3.850-4.555 W·m^-1·K^-1, respectively. At the temperature range of about -9.41 to 9.41 ℃, the thermal diffusivities of the dried mudstone, the mudstone bearing methane hydrate, the dried sandstone, and the sandstone bearing methane hydrate are 0.712-0.894 mm²·s^-1, 0.792-1.006 mm²·s^-1,1.198-1.674 mm²·s^-1, and 1.403-1.769 mm²·s^-1,respectively. The data show that it is a good means to explore the existence of hydrate by measuring the thermal conductivity of intervals bearing gas hydrate.

Key words: gas hydrate, thermal conductivity, thermal diffusivity, microstructure, mudstone, sandstone

中图分类号:

万丽华, 梁徳青, 李栋梁, 关进安. 祁连山冻土区天然气水合物储层岩石热物性实验研究[J]. 现代地质, 2018, 32(02): 385-391.

WAN Lihua, LIANG Deqing, LI Dongliang, GUAN Jin’an. Experimental Study of Thermophysical Properties of Reservoirs Bearing Gas Hydrates in Qilian Mountain Permafrost[J]. Geoscience, 2018, 32(02): 385-391.

图/表 11

图1 实验装置系统图 1.真空压力表;2.真空泵;3.氟塑料圆柱环;4.水合物样品;5.导热探头(探头直径小于试样直径的1/3);6.背景材料;7.不锈钢反应釜;8.压力表;9.压力传感器;10.铂电阻温度传感器;11.管路12.数据采集仪;13.导热测试设备;14.电脑工作站;15.储气瓶;16.空气浴;V1-V6.阀门;B1-B4.螺栓

Fig.1 Sketch map of the experimental setup

图2 泥岩、砂岩热物性测试样品宏观特征图

Fig.2 Microscopic photos of mudstone and sandstone samples

图3 泥岩冷冻样品显微特征图

Fig.3 Micro-feature photos of frozen mudstone

图4 砂岩冷冻样品显微特征图

Fig.4 Micro-feature photos of frozen sandstone

表1 岩石样品主要特征

Table 1 Main features of rock samples

编号	钻孔	发现水合物层段	层段主要岩性	水合物主要产状类型	岩性特征
样品1	SR-1井	312 m处	泥岩	浸染状	黑褐色,含钙质细纹层
样品2	DR-1井	312 m处	细砂岩	孔隙状	成分以石英为主,坚硬,局部较易破碎

图5 泥岩、砂岩及其含水合物导热系数

Fig.5 Thermal conductivity of dried mudstone and dried sandstone and these stones bearing methane hydrate

表2 泥岩烘干后导热系数、热扩散系数

Table 2 Thermal conductivity and thermal diffusion coe-fficient of the dried mudstone sample

T/℃	d/(W·m^-1·K^-1)	α/(mm²·s^-1)
-9.41	0.850	0.712
-8.72	0.853	0.755
-5.32	0.816	0.788
-3.74	0.721	0.855
-2.48	0.657	0.786
-1.42	0.633	0.832
1.78	0.650	0.825
3.42	0.602	0.775
5.34	0.606	0.825
8.01	0.613	0.721
9.41	0.577	0.894

表3 含水合物泥岩导热系数、热扩散系数

Table 3 Thermal conductivity and thermal diffusion coe-fficient of the mudstone bearing methane hydrate

T/℃	d/(W·m^-1·K^-1)	α/(mm²·s^-1)
-9.70	1.026	0.792 2
-7.07	1.050	0.788 8
-5.14	0.968	0.773 5
-4.72	0.937	0.885 0
-3.69	0.766	0.834 7
-1.39	0.733	0.978 6
0.44	0.746	0.981 6
2.32	0.746	0.958 0
4.15	0.749	1.006 0
5.25	0.747	0.880 2
6.63	0.717	0.880 2
7.95	0.704	0.892 0

表4 砂岩烘干后导热系数和热扩散系数

Table 4 Thermal conductivity and thermal diffusion coe-fficient of the dried sandstone sample

T/℃	d/(W·m^-1·K^-1)	α/(mm²·s^-1)
-8.11	1.155	1.412
-6.27	1.158	1.550
-4.56	1.271	1.340
-2.71	0.958	1.198
-1.75	0.857	1.292
1.18	0.879	1.256
3.14	0.873	1.627
6.71	0.934	1.674
9.28	0.8282	1.654

表5 含水合物砂岩导热系数和热扩散系数

Table 5 Thermal conductivity and thermal diffusion coe-fficient of the sandstone sample bearing methane hydrate

T/℃	d/(W·m^-1·K^-1)	α/(mm²·s^-1)
-9.77	4.510	1.403
-7.96	4.456	1.700
-6.32	4.530	1.630
-4.33	4.555	1.640
-2.33	4.250	1.769
-0.46	4.001	1.635
1.50	3.870	1.508
3.43	3.899	1.582
5.17	3.850	1.660

图6 泥岩、砂岩及其含水合物热扩散率

Fig.6 Thermal diffusion coefficients of dried mudstone and dried sandstone and these stones bearing methane hydrate

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