The age constraints on natural gas strata and its geological signficance of Well Y in Hari depression, Yingen-Ejin basin
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摘要:
银额盆地哈日凹陷Y井钻遇多层天然气显示层,并对井深2946.0~2951.0m井段射孔压裂,获天然气9.15×104m3/d(无阻流量)。对浅层天然气显示层确定为白垩系银根组无异议,但获得工业气流的产层时代归属尚存争议。通过镜质体反射率(Ro)随深度的变化规律的研究,以及利用钻井岩心实验分析获得泥岩地球化学特征对沉积物源区沉积环境的判别,约束了二叠系与白垩系巴音戈壁组的不整合界面位于第9次取心(岩心底深2593.80m)与第10次取心(岩心顶深2909.60m)之间;地球物理测井自然伽马、电阻率等曲线在2792.0m出现突变,确定二叠系与白垩系巴音戈壁组的不整合界面为2792.0m。明确了Y井天然气产层为二叠系,指示了二叠系良好的油气资源前景,区内今后油气勘探应以二叠系为主要目的层。
Abstract:Well Y intersects several natural gas strata in Hari depression, Yingen-Ejin basin. It is characterized by open flow capacity of 91500m3 natural gas per day after hydra perforating and fracturing between 2946.5m and 2951.0m. This paper has no suspect on the oil source of the superficial zone of this well, which came from the Cretaceous Yin'gen Formation. Additionally, there exists controversy on the stratigraphic age of the industrial gas flow. Based on the Roversus depth correlation and geochemical characteristics discrimination of well mudstones, the unconformity between the Permian and the Cretaceous Bayin'gebi Formation was identified in the depth between 2593.80m and 2909.60m. Meanwhile, the gamma ray and specific resistance curve of the geophysical log revealed obvious changes at the 2792.0m of the tenth coring. Moreover, this research confirms that 2792.0m is the unconformity between the Permian and Cretaceous Bayin'gebi Formation. Particularly, it means that the natural gas derived from Permian has good hydrocarbon prospects. The oil-gas exploration in future should mainly focus on the Permian strata.
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Keywords:
- Hari depression /
- Yingen-Ejin basin /
- natural gas reservoir /
- unconformity interface /
- Permian /
- Cretaceous
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致谢: 陕西省延长石油(集团)有限责任公司勘探公司银额指挥部为样品采集提供了方便,中国地质调查局西安地质调查中心实验测试中心进行了样品分析,在此一并表示衷心的感谢。
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图 1 Y井井位及区域地质略图[10]
1—新生界;2—中生界;3—上古生界;4—下古生界;5—古生界;6—中元古界;7—古中元古界;8—古元古界;9—元古宇;10—新太古界-元古宇;11—新太古界;12—超基性岩;13—火山岩;14—地名;15—工业气井
Figure 1. The location of Well Y and regional geological sketch map
图 3 Y井泥岩稀土元素配分模式[15]
Figure 3. Chondrite-normalized REE patterns for mudstones of Well Y
图 4 沉积物源区构造环境判别图[15]
A—大洋岛湖;B—大陆岛湖;C—活动陆缘;D—被动陆源
Figure 4. Tectonic setting discrimination diagrams with trace elements of sedimentary provenance
表 1 Y井泥岩稀土和微量元素分析结果
Table 1 REE and trace elements data of mudstones from Well Y
10-6 送样号 HC-32 HC-33 HC-34 HC-35 HC-36 平均 送样号 HC-32 HC-33 HC-34 HC-35 HC-36 平均 取心回次 第9次 第10次 取心回次 第9次 第10次 井深/m 2592.9 2909.6 2911.1 2911.7 2912.9 井深/m 2592.9 2909.6 2911.1 2911.7 2912.9 La 27 22.2 20.4 21 25.5 22.3 Co 17 15.4 19.2 17.8 20.8 18.3 Ce 64.2 46.2 43.7 44.6 50.9 46.35 Rb 168 122 112 99 136 117 Pr 7.96 5.57 5.2 5.21 6.27 5.56 Cs 38 27.3 39 33.3 37.8 34.4 Nd 31 21.5 19.4 20.3 24.1 21.3 Mo 0.84 0.19 0.07 0.1 0.22 0.14 Sm 6.93 4.6 4.34 4.36 5.12 4.61 As 53.2 13.3 16 81.6 29.8 35.2 Eu 1.44 1.01 0.92 0.89 1.04 0.97 Sr 327 404 394 396 326 380 Gd 6.08 4.01 3.98 4.15 4.57 4.19 Ba 573 525 522 481 615 536 Tb 0.96 0.65 0.66 0.65 0.75 0.68 V 140 119 118 113 127 119 Dy 5.53 4.04 4 3.95 4.41 4.1 Sc 13.9 14 12.4 11.7 15.4 13.4 Ho 1.12 0.85 0.84 0.83 0.92 0.86 Nb 11.6 10.2 10.4 10.2 11.4 10.6 Er 3.13 2.51 2.44 2.42 2.64 2.5 Ta 0.86 0.81 0.8 0.8 0.86 0.82 Tm 0.48 0.39 0.38 0.38 0.4 0.39 Zr 159 170 172 166 192 175 Yb 3.14 2.54 2.57 2.48 2.68 2.57 Hf 4.36 4.54 4.52 4.46 5.14 4.67 Lu 0.47 0.39 0.4 0.38 0.4 0.39 B 76.3 58.5 72.7 73.2 67.7 68 总计 159.4 116.5 109.2 111.6 129.7 116.8 Ga 21.4 21.6 23.8 21.9 25 23.1 Y 28.7 22.3 21.9 21 24.2 22.4 Se 0.22 0.14 0.13 0.16 0.26 0.17 Pb 13.3 21.9 23.7 23.2 25.8 23.65 U 2.56 2.88 1.82 1.72 2.53 2.24 Cr 75.5 80.3 76.4 72.5 77.2 76.6 Th 12.6 8.73 8.67 7.7 9.2 8.58 Ni 36.3 41.9 41 38.4 48.4 42.4 -
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