纵、横波速度识别火成岩气、水层影响因素实验研究

摘要/Abstract

摘要：

为了揭示纵、横波速度识别火成岩气、水层的物理机理与储层内在因素的联系,指导火成岩储层流体类型识别,选取准格尔盆地石炭系火成岩岩心,采用超声波脉冲法对其纵、横波速进行测量,分别获取了干燥和饱和水状态下岩心的纵、横波速度,并进一步分析了流体类型、孔隙度、密度和岩性等地层因素对纵、横波速度的影响。地层含气会引起纵波速度和纵、横波速比明显减小,而对横波速度影响较小;在低孔隙层段,气、水层的纵、横波速差异特征弱化,流体类型识别较困难;火成岩岩性复杂,纵波速度受SiO₂含量影响较大,应区分不同岩性进行流体识别。基于实验认识,分岩性建立V_P/V_s—R_t交会图对研究区测试层段进行气、水层识别,中—基性岩和酸性岩V_P/V_s分别为1.85和1.75时,气、水层被有效区分,但受到低孔隙度影响,气、水层响应特征差异弱化,不能区分气层与气水同层。

关键词: 火成岩, 纵、横波速度, 物理机理, 影响因素, 流体识别

Abstract:

In order to reveal the link between the physical mechanism of identifying gas and water zones in igneous rock with longitudinal and transverse waves' velocity, and the internal factors of reservoirs, and guide the identification of fluid types in igneous rock, the Carboniferous igneous rock core of the Junggar Basin was selected, and its longitudinal and transverse waves' velocities were measured via the ultrasonic pulse method . The longitudinal and transverse waves' velocities of the core in the dry state and the water-saturated state were obtained. In addition, the influence of the internal factors of reservoirs like the fluid types, porosity, density and lithology on elastic wave velocity were analyzed. The research showed that the gas-bearing state of the formation would cause the significant decrease in both the longitudinal wave velocity and the ratio of longitudinal to transversal wave velocities, but had a small impact on transversal wave velocity. In formations with low porosity, it was difficult to identify the fluid types because the difference in the characteristics of the longitudinal and transverse waves' velocities in gas and water zones was weakened. Due to the complex lithology in igneous rock and the great influence of SiO₂ content on elastic wave velocity, fluid types should be identified by different lithology. Based on the above conclusion and in order to highlight logging responses of fluids, V_P/V_s-R_t crossplots were established by different lithology to identify gas and water zones in tested formations in the research area. For intermediate-basic rock and acid rock, the V_p/V_s values are 1.85 and 1.75, respectively, which can be used to distinguish the gas zone and the water zones effectively; however, due to the influence of low porosity, it is difficult to effectively distinguish between the gas zone and the gas-water coexistence zone.

Key words: carboniferous igneous rock, longitudinal and transverse wave velocity, physical mechanism, influential factors, fluid identification

中图分类号:

P631

贾俊,李昌,王亮,赵宁. 纵、横波速度识别火成岩气、水层影响因素实验研究[J]. 油气藏评价与开发, 2018, 8(5): 8-13.

Jia Jun,Li Chang,Wang Liang,Zhao Ning. Experimental study on identification of influencing factors of igneous gas and water layer by longitudinal and shear wave velocities[J]. Reservoir Evaluation and Development, 2018, 8(5): 8-13.

图/表 8

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参考文献 31

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序号	岩样编号	岩性	孔隙度, %	饱和样品				干燥样品				纵/横波速比
序号	岩样编号	岩性	孔隙度, %	密度/ （g·cm^-3）	V_P/ （km·s^-1）	V_S/ （km·s^-1）	V_P/V_S	密度（g·cm^-3）	V_P/ （km·s^-1）	V_S/ （km·s^-1）	V_P/V_S	V_P饱/V_P干	V_S饱/V_S干
1	00429	玄武岩	0.20	3.02	3.87	2.11	1.83	2.81	3.08	2.02	1.52	1.26	1.04
2	05640		2.10	2.85	3.36	2.11	1.59	2.66	3.19	2.33	1.37	1.05	0.91
3	16487		14.80	2.80	3.88	2.17	1.79	2.41	2.74	1.46	1.88	1.42	1.49
4	16488		13.70	2.74	4.02	2.05	1.96	2.35	2.44	1.97	1.24	1.65	1.04
5	04678	安山岩	15.30	2.68	2.38	1.45	1.64	2.29	2.36	1.49	1.59	1.01	0.97
6	04673		13.00	2.62	2.53	1.61	1.57	2.27	2.50	1.48	1.69	1.01	1.09
7	04400		1.00	2.69	4.24	2.74	1.55	2.54	3.29	2.19	1.51	1.29	1.25
8	04404		2.60	2.54	3.99	2.00	1.99	2.36	3.09	2.01	1.53	1.29	1.00
9	20321	闪长玢岩	8.00	2.74	3.02	1.89	1.59	2.46	3.17	1.75	1.82	0.95	1.08
10	05568		9.20	2.64	3.86	2.12	1.83	2.37	2.90	1.83	1.59	1.33	1.16
11	05579		9.90	2.60	3.45	1.88	1.84	2.33	2.96	1.93	1.54	1.17	0.97
12	20329		11.10	2.66	3.01	1.79	1.68	2.40	3.17	1.80	1.76	0.95	0.99
13	06103	花岗斑岩	6.80	2.62	4.20	2.53	1.66	2.39	3.79	2.46	1.54	1.11	1.03
14	06106		3.30	2.64	3.91	2.05	1.91	2.45	3.41	2.06	1.66	1.15	1.00
15	06109		8.70	2.64	2.95	1.80	1.64	2.37	2.91	1.84	1.58	1.01	0.98
平均值			7.90	2.70	3.51	2.02	1.74	2.43	3.00	1.91	1.59	1.18	1.07

岩性	ρ 和 V_P		ρ 和 V_S
岩性	回归公式	相关系数	回归公式	相关系数
玄武岩	ρ=1.349V_P^0.608	0.89	ρ=2.191V_S^0.232	0.55
安山岩	ρ=1.795V_P^0.269	0.87	ρ=2.087V_S^0.218	0.89
闪长玢岩	ρ=1.541V_P^0.394	0.80	ρ=3.251V_S^-0.512	0.94
花岗斑岩	ρ=2.269V_P^0.049	0.37	ρ=2.378V_S^0.016	0.14