【作者】 许国明；

【导师】 陈洪德；

【作者基本信息】 成都理工大学 ， 地层与古生物学， 2010， 博士

【摘要】 研究区处于松潘-甘孜地槽和扬子地台西北大陆边缘槽台过渡带。自从晋宁运动扬子地台基底形成以来,古中生代海相(Z-T2)总体处于被动大陆边缘的构造背景下,加里东至印支早期构造大阶段中,在川西槽台过渡带,槽区形成克拉通边缘裂陷槽盆地,台区形成克拉通周边沉降盆地(台缘)和克拉通内坳陷盆地(台内)。这些不同性质的原型盆地在其形成演化过程中都曾形成过有利烃源岩发育的构造沉积背景。本次研究以深灰色以深的灰岩、泥岩作为烃源岩,编制的不同层系烃源岩平面展布图显示槽区、龙门山区和川西坳陷区烃源岩层系有所不同,槽区烃源岩依次为泥盆系(D)、志留系(S)、上三叠统(T3)和下寒武统(∈1);龙门山区为泥盆系(D)和中二叠统(P2);川西坳陷以中二叠统(P2)和下中三叠统(T1-T2)为主,此外有部分为下寒武统(∈1)。海相∈1、P烃源岩评价结果表明,下寒武统Ⅰ类烃源区位于绵阳、绵竹一线的西北地区,生烃强度30～130×108m3/km2。Ⅱ类烃源区位于绵阳、德阳、中江、金堂一带,生烃强度10～30×108 m3/km2。Ⅲ类烃源区位于什邡、成都以西地区,生烃强度小于10×108m3/km2。中二叠统Ⅰ类烃源区位于汉旺、彭州、雾1井以东地区,生烃强度30～55×108m3/km2。其以西地区为Ⅱ类烃源区,生烃强度24～30×108m3/km2。上二叠统烃源岩,以中江、新都、温江一线为界,其西部为Ⅱ类烃源区,生烃强度10～30×108m3/km2。其东部为Ⅲ类烃源区,生烃强度8～10×108m3/km2。对龙门前山源岩、油苗、沥青样品饱和烃色谱(GC)、色谱-质谱(GC-SQ)以及碳同位素等资料分析对比认为:陆相储层中的油苗、沥青具有海陆混源,海相储层具有海相多源供烃的特征;如在厚坝陆相油砂岩(J2s1)和中坝气田中46井T3x2储层内沥青的色谱-质谱具有典型的海相图谱特征,而与D2j源岩图谱近似,江油汉旺地区的沙窝子组(D3s)与武都镇飞仙关组(T1f)和鱼洞梁仙关组(T1f)储层沥青样品的GC-SQ高度相似;烃源岩演化分析表明:川西古生界台缘坳陷P3、D、∈、Z的源岩在安县运动(T3X3-4)之前均已成熟,可以向高处的斜坡和台内(即现今的龙门前山至川西坳陷一带)运移,因此预测在龙门前山至川西坳陷一带未遭后期构造运动破坏的层系可能找到“海生海储”、“海生陆储”的油气藏。通过川西龙门山地区北段江油-平武、中段汉旺-大火地和南段映秀-三江等地野外石油地质调查及相关样品分析化验以及龙深1井、川科1井样品成果和盆地内钻井地化样品成果的分析,指出了研究区海相古、中生界整体而言,主要发育3套区域性生储盖组合:①以盆地-下斜坡相Z1ds黑色页岩、深灰色微晶灰岩、∈1黑色页岩为烃源/以Z2dn暴露藻礁、藻屑滩孔缝性白云岩为储层/∈1、S泥页岩为盖层;②以Z2dn2、∈1及盆地相S1灰黑色页岩、D1-2盆地-深水陆棚相黑色页岩、黑灰色泥微晶灰岩为烃源/S1-2、D2-3砂岩、礁滩相灰岩、云岩为储层/D2-3与C1z泻湖-潮坪相泥页岩为盖层;③以外缓坡相和沼泽相P2-3暗色泥质泥微晶灰岩、黑色页岩为烃源岩/P2-3、T1-2滩相灰岩、云岩为储层/T1-2泥岩、膏岩、T3泥岩为盖层。这几套组合的存在是川西海相古油气藏和现今油气藏得以形成的基础。其中第一套组合在川西坳陷埋深大于8000米,第二套组合仅发育于川西西缘龙门山区,可能对川西第三套组合储层有一定规模补给,最具现实勘探意义的是第3套P-T的组合。区带综合评价认为:川西地区都江堰-江油断裂以西的龙门山构造带受印支晚期-喜山期多期构造运动影响,古中生代地层遭受强烈的抬升剥蚀、挤压推覆,构造变形严重,断裂通天,油气保存条件遭到严重破坏,整体成藏条件差;都江堰-江油断裂以东川西坳陷西缘,地震剖面揭示在坳陷西缘古中生界还保存有较完整的“原地体”构造带,在“原地体”构造带上沉积多套巨厚的印支中晚-燕山期海陆相盖层,西侧被江油-都江堰断裂之下多条未露头的低角度叠瓦逆冲断层封挡,保存条件相对较好,海相层系早期成藏的圈闭可能未遭印支晚期至喜山期的构造运动的严重破坏,只是被调整改造,印支晚期后深埋,油转化成气,在新的成藏条件下形成新的油气藏,因此,综合生储盖条件及构造演化分析认为:在江油-都江堰断裂以东、川西坳陷西缘古中生界“原地体”构造带内极可能寻找到大中型的天然气藏,应是川西海相油气勘探重要区带;另外,川西坳陷中部-川中隆起的区域地震剖面还揭示:古中生界还发育孝泉-新场-丰谷构造带、龙泉山构造带、中江-回龙鼻状构造带,它们保存条件优越,早中三叠统内可能发育台内滩相储层,可能寻找到大中型的构造-岩性或岩性油气藏,也是川西海相油气勘探重要区带。更多还原

【Abstract】 The sturdy area located transition zone between Songpan-Ganzi geosyncline and northwest continent margin of Yangtze platform. Platform base formed during Jinning activity,belonged to passive continental margin from Paleozoic to Mesozoic. In the transition zone of western Sichuan, The geosyncline evolved cratonic marginal rift basin From Caledonian to early Indosinian, platform evolved cratonic around basins and intracratonic sag basins. These prototype basins of different property had favorable tectonic-deposition setting of the source rock. This research defined dark gray limestone, shale as source rock, mapped the map of plane distribution of source rock. Source rock in geosyncline contained: Devonian, Silurian, Upper Triassic, Lower Cambrian and Middle Permian, which is different from Longmenshan area, While Middle Permian and Middle-Lower Triassic in depression of western Sichuan. By evaluation of source rock, indicated that TypeⅠsource rock area located northwest of the line between Mianyang and Mianzhu. Density of producting hydrocarbon is 30～130×108m3/km2. TypeⅡsource rock area located Mianyang, Deyang, Zhongjiang, Jintang. Density of producting hydrocarbon is 10～30×108 m3/km2. TypeⅢsource rock area located westof the line between Shifanf and Chengdu. Density of producting hydrocarbon is less than 10×108m3/km2. Density of producting hydrocarbon of TypeⅠsource rock of Middle Permian is 30～55×108m3/km2 in east of the line between Hanwang, Pengzhou and Wu1 well. West of the line is TypeⅡsource rock of Upper Permian, Density of producting hydrocarbon is 10～30×108m3/km2. East of the line is TypeⅢsource rock, Density of producting hydrocarbon is 8～10×108m3/km2.By the analysis of source rock, oil seepage, GC, GC-SQ and carbon isotope, we deem that source of oil seepage and asphalt in continental reservoir came from both continental and marine. Marine reservoir had characteristics of multi-source. For example, the characteristic of GC-SQ in continental sandstone (J2s1) of Houba is similar to Zhong 46 well (T3x2 reservoir), and similar to the map of source rock(D2j), GC-SQ of asphalt sample of Shawozi formation in Hanwang, Jiangyou, Feixiangguan formation in Wudu, and Yutongliang are highly similar. From the analysis of evolution of source rock indicated that source rock was matured before Anxian activity. Oil and gas migrated to slope and interplatform(From front Longmenshan to depression of western Sichuan). So predicted that the area from front Longmenshan to depression of western Sichuan was not destroyed by later tectonic movement, may find petroleum reservoir of marine source rock– marine reservoir and marine source rock– continental reservoir.By the petroleum geological survey in Longmenshan area and the analysis of related samples, we had acquaintanceship for regional source-reservoir-seal combinations as follow:①Black shale, dark gray microcrystalline limestone (Z1ds), black shale (∈1) in basin-lower slope as source rock. Fracture dolomite (Z2dn) in exposed shoal-reef as reservoir. Shale(∈1, S) as seal.②Gray-black shale (Z2dn2,∈1, S1) in basin and black shale, dark gray microcrystalline limestone (D1-2) in basin-shelf as source rock. Sandstone, limestone, dolomite (S1-2、D2-3) in shoal-reef. as reservoir. Shale (D2-3, C1z) in lagoon-tidal flat as seal.③Dark muddy microcrystalline limestone, black shale (P2-3) in outer ramp and swamp as source rock. Limestone, dolomite (P2-3、T1-2) in shoal as reservoir. Mudstone, gypsum and salt rocks (T1-2) and mudstone (T3) as seal. These combinations had preserved the oil and gas in western Sichuan. The burial depth of first combination is more than 8,000 meters in depression of western Sichuan. The second combination only developed in Longmenshan arera, which supply the third combination to some extent. The third combination had exploration significance.Comprehensive evaluation: By the influence of late Indosinian - Himalayan tectonic movement, Paleozoic-Mesozoic strata was uprifted and eroded, thrusted, deformed in western Sichuan. The condition for oil and gas preservation was destroyed. From seismic profiles, indicated that Paleozoic-Mesozoic strata had complete“autochthon”tectonic zone, which was covered by marine-continental seal in middle-late Indosinian-Yanshan epoch. And be seal by imbricate low-angle thrust fault in west, preservation condition was better. Oil and gas from order destroyed reservoir migrated into new reservoir. From the angle of comprehensive evaluation, east of Jiangyou-Dujiangyan fracture and west of depression in western Sichuan may find medium and large reserves of natural gas. Western Sichuan, Longquanshan tectonic zone, Zhongjiang-Huilong nose tectonic zone had favorable preservation condition, May developed shoal facies reservoir, which are key area for exploration in western Sichuan.更多还原