四川盆地陆相油型气分布、成因及来源

四川盆地陆相天然气类型主要为煤型气,而油型气的含量、分布较少,因此在研究四川盆地有利于油型气生成的陆相烃源岩特征及分布的基础上,从全盆的角度通过天然气地球化学特征结合构造条件分析了陆相油型气的分布、成因与来源情况。研究表明:1川西地区须一段、川中地区中下侏罗统发育腐泥型烃源岩,川中地区须一段发育薄层的腐殖腐泥型烃源岩;2油型气在川西地区须二段少量分布,在川中地区中下侏罗统大量分布,须二、须六段少量分布,在川南地区须家河组各段有一定量分布;3川西地区须二段油型气为二次裂解成因,来自川西地区须一段腐泥型烃源岩,川中地区中下侏罗统和须二、须六段油型气为干酪根裂解成因,中下侏罗统和须六段油型气来自川中地区中下侏罗统腐泥型烃源岩,须二段油型气来自川中地区须一段薄层的腐殖腐泥型烃源岩,川南地区须家河组各段油型气为二次裂解成因,来自下伏海相地层。     

地球内部物质物性的原位高温高压研究：大体积压机与同步辐射源的结合

四川盆地是一个大型复合含气为主、含油为辅的叠合盆地。多旋回的沉积演化过程,孕育了多套海相、陆相烃源岩,且不同区域发育不同成因类型的烃源岩。目前下寒武统、志留系、下二叠统、上二叠统和上三叠统五套主要烃源岩均已进入高演化阶段,并以成气为主。由于多阶成烃、混源聚集和后期遭受TSR次生蚀变等成藏过程的复杂性使得天然气组分较干、碳同位素组成复杂,常规方法进行气源对比较困难。文中在对四川盆地沉积演化背景分析的基础上,通过对有效烃源岩发育特征和分布规律的探讨,分区域进行了气藏的分析,特别是对天然气组分、非烃组成(H2S、CO2、N2等)和碳同位素等资料综合研究的基础上,基本确定了各区块各含气层系的主力源岩。认为川东主力产层石炭系、三叠系和二叠系的气源分别为志留系、上二叠统龙潭组和下二叠统;川南气区震旦系灯影组、寒武系、二叠系和三叠系产层的气源分别主要来自下寒武统,上、下二叠系源岩;川西气区侏罗系和三叠系须家河组主产层的气源主要来自三叠系须家河组煤系烃源岩,下二叠统和嘉陵江组产层气源则可能主要来自二叠系;川中主要为产油区,下侏罗统自流井群原油应来自侏罗系源岩,浅部层系气源为上三叠统须家河组的陆相烃源岩,深部气藏则为寒武系烃源岩。由于川东北部烃源岩发育层数最多,且质量都较好,因此川东北部是烃类最富集的地区,也是勘探潜力最大的地区。     

泸州地区上三叠统须家河组天然气成因类型与来源

通过对天然气的组成和碳同位素组成的综合研究,综合实际地质条件,明确了泸州古隆起上三叠统须家河组天然气的成因类型和分布规律,并细分了不同气藏的气源贡献和来源特征。结果表明研究区存在3种来源与成因类型天然气:①以须家河组煤系为来源的自生自储型天然气;②以深层来源气为主的天然气;③以须家河组煤系烃源为主,深层来源为辅的混合型成因气。     

藏北羌塘盆地QK-1井中侏罗统烃源岩地球化学特征

QK-1天然气水合物钻探试验井位于西藏羌塘盆地毕洛错地区,主要钻遇中侏罗统夏里组粉砂质泥岩和布曲组灰岩。其有机质丰度、有机质类型、有机质成熟度等有机地球化学特征表明,南羌塘地区中侏罗统烃源岩的有机质丰度偏低,夏里组泥岩TOC介于0.26%~0.38%之间,达到差-中烃源岩标准,而布曲组灰岩TOC介于0.02%~0.08%之间,仅局部达到差烃源岩标准;两个组的烃源岩有机质类型主要为Ⅱ₂型及Ⅲ型,较利于天然气的生成,其中夏里组的生气能力优于布曲组;该区烃源岩热演化程度较高,Ro为1.31%~1.63%之间,均达到高成熟阶段,而夏里组有可能已进入干气阶段。基于冻土区天然气水合物成藏条件分析,综合考虑夏里组烃源岩及沉积厚度特征,认为中侏罗统夏里组具备良好的天然气水合物勘探前景。     

库车前陆坳陷形成大气区的烃源岩条件

随着勘探的深入,库车前陆坳陷逐渐成为我国重要的大气区.本文对其形成大气区的关键条件之一的烃源岩特征进行了深入研究.库车坳陷主要分布中-上三叠统浅湖-半深湖相泥质烃源岩和中-下侏罗统煤系烃源岩,具有厚度大、丰度高、类型差和成熟度高的特点.三叠-侏罗系烃源岩具有十分丰富的天然气生成量,天然气来源不是制约库车坳陷天然气勘探的因素;根据三叠-侏罗系烃源岩的类型特征和成熟度特征认为库车坳陷资源丰富、以气为主,在天然气的生成上侏罗系烃源岩的贡献要大于三叠系.     

四川盆地中三叠统-上三叠统马鞍塘组天然气藏特征和有利勘探地区

四川盆地中三叠统雷口坡组勘探已近40年,但迄今为止只发现了两个大中型气藏.近年来,雷口坡组钻井油气显示活跃,展示了良好的勘探前景.四川盆地中三叠统气藏储层主要位于底部雷一段、顶部雷三一雷四段,天然气主要来源于上二叠统龙潭组和上三叠统须家河组烃源岩,各气藏天然气组分特征也不尽相同,储集空间均以各类次生溶蚀孔隙为主,多为低-中孔低渗的孔隙型或裂缝一孔隙型储层.气藏盖层发育,均具备良好的直接盖层和区域盖层条件.上三叠统马鞍塘组储层主要位于其顶、底部的(藻)砂屑灰岩和泥晶灰岩,烃源岩和盖层与雷三、雷四段成藏条件相似.本文将四川盆地中三叠统一上三叠统马鞍塘组生储盖组合特征概括为两种类型:1)上二叠统龙潭组烃源岩+雷一-雷二段滩相储层+雷口坡组膏盐盖层;2)上三叠统烃源岩+雷三-雷四段-马鞍塘组底部(礁)滩相储层和(或)风化壳古岩溶储层+上三叠统泥质盖层.将来的油气勘探应更加重视对第二组合的关注.龙门山中南段前缘地区应是中三叠统雷三一雷四段和上三叠统马鞍塘组油气勘探最有利的地区.     

川西前陆盆地中部须家河组煤成气资源与勘探

川西前陆盆地须家河组作为上三叠统重要的含煤地层,含有多套烃源岩。采用沉积有机碳法对各套烃源岩的特征进行了研究。结果表明,烃源岩中含有丰富的有机质,其类型以Ⅲ型干酪根为主,部分为Ⅱ型干酪根。烃源岩总体上成熟度较高,天然气总生成量大,不同地区和各套烃源岩的分布特征和生烃潜力存在明显差异,有机碳值变化幅度大,天然气产出量不均衡。不同地区,烃源岩非均质性和盆地构造演化及沉积特征变化复杂,造成了川西地区中部勘探面临一些问题。这些问题需要紧密结合前陆盆地构造发育和含煤地层沉积的特点,研究烃源岩分布差异性特征,从煤系烃源岩、天然气成藏理论和勘探技术等方面加以解决。     

川西坳陷中段上三叠统须家河组二段原油裂解成因天然气发现及成藏模式初探

川西坳陷中段具备多套烃源层、多个烃源区、多期油气生成、多期油气成藏同时又经历了多个构造期调整和破坏,纵向上发育的多套生储盖组合孕育了多层含气层系。天然气碳同位素分析表明,该区上三叠统须家河组产出的部分天然气乙烷碳同位素具有明显偏负的特征,相关图版的判别显示,这部分天然气具有原油裂解气的性质。同时在研究区上三叠统须家河组储层中发现了大量的储层沥青充填物,通过岩芯观察、显微照片、元素、热解等分析,发现该储层沥青充填物具有多种类型、多种分布形态、边界较为清楚等特征,且这些沥青充填物的反射率较高,尤其是须二段的储层沥青,这一特征与焦沥青的基本特征类似,表现为油藏裂解后残余物的特征,原油裂解气和焦沥青的发现证实了川西坳陷中段须家河组古油藏的存在。在此基础上,通过综合分析生油及裂解条件等,对研究区须家河组古油藏裂解气成藏模式进行了初步探讨,将这一过程分为印支晚期古油藏形成、燕山中期古油藏裂解、燕山晚期-喜山期气藏调整三个连续的阶段,这对深化认识川西坳陷中段天然气的成因和分布具有一定的意义。     

川中与川西地区陆相煤成气地球化学特征差异

对四川盆地川中与川西地区陆相气藏天然气组分、碳同位素和氢同位素数据进行分析。结果表明:川西地区上三叠统须家河组和侏罗系天然气以干气为主,川中地区上三叠统须家河组天然气以湿气为主;天然气中甲烷含量、干燥系数和氮气含量等在川西地区纵向上有规律变化。川中地区上三叠统天然气甲烷碳同位素轻于川西地区天然气甲烷碳同位素;乙烷碳同位素值除川中八角场大安寨组气藏部分气样表现为油型气外,川中地区须家河组气藏和川西地区须家河组、侏罗系气藏均为煤型气。造成上述差异的主要原因是:川西地区须家河组在须三段沉积末期就进入生烃门限,川中地区须家河组直到早侏罗世才开始生烃。川西地区侏罗系次生气藏是须家河组气源在高压下以混合相通过断裂形成的,川中地区须家河组气藏主要以游离相汇聚至物性较好的砂体中。     

贺兰山汝箕沟地区及中卫探区上三叠统烃源岩初步评价?

贺兰山中卫探区是中国石化胜利油田分公司2002年8月登记的勘探新区,迄今为止,探区内还没有钻井资料,总体的勘探程度非常低。为研究中卫探区上三叠统烃源岩的生烃能力,对探区以北汝箕沟地区上三叠统露头区暗色泥岩进行了取样分析,结果表明：该泥质岩的有机碳含量为3.03%,总烃含量0.0025%;干酪根显微组分以镜质组为主,类型指数-72.5,属Ⅲ型干酪根;Ro值为0.93％,有机质热演化已达到成熟阶段。与探区以东鄂尔多斯盆地延长组、石炭系-二叠系煤系地层相比较,汝箕沟地区上三叠统泥质岩样品的有机质丰度较高,成熟度好,可作为较好的气源岩。晚三叠世时期,中卫探区和汝箕沟地区同属滨浅湖相沉积环境,中卫探区更靠近湖盆中心,为更有利的生烃沉积相带。中卫探区上三叠统烃源岩应具有较好的生气能力,应以该套烃源岩为基础,加强中卫探区内天然气的勘探。     

四川盆地中三叠统-上三叠统马鞍塘组天然气藏特征和有利勘探地区

四川盆地中三叠统雷口坡组勘探已近40年,但迄今为止只发现了两个大中型气藏.近年来,雷口坡组钻井油气显示活跃,展示了良好的勘探前景.四川盆地中三叠统气藏储层主要位于底部雷一段、顶部雷三一雷四段,天然气主要来源于上二叠统龙潭组和上三叠统须家河组烃源岩,各气藏天然气组分特征也不尽相同,储集空间均以各类次生溶蚀孔隙为主,多为低...     

川西侏罗系上沙溪庙组砂岩中绿泥石的成岩耗水作用及其油气地质意义

通过对川西坳陷中侏罗统上沙溪庙组砂岩储层样品的普通薄片和铸体薄片观察分析,讨论了砂岩中绿泥石环边胶结物的特征、形成期次以及油气地质意义。研究表明,富SiO2的孔隙流体对初期形成的绿泥石环边胶结物产生溶蚀作用。如果孔隙流体性质呈现适合石英胶结物形成时,当流体渗透过绿泥石环边到达石英碎屑颗粒表面,由于对绿泥石环边的溶蚀作用使得流体中SiO2浓度降低,则不足以形成石英胶结物,从而保护了孔隙空间不被充填。在成岩过程中矿物蚀变成绿泥石发生的＂成岩耗水＂作用使得地层水减少,地层压力降低,与围岩形成压力差,有利于油气运移和富集。     

Geochemical Characteristics and Genetic Types of Natural Gas in the Xinchang Gas Field, Sichuan Basin, SW China

The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane (88.99%–98.01%), and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5~(th) member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4~(th) member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3~(rd) and 4~(th) members of the Xujiahe Formation. The gases reservoired in the 2~(nd) member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma'antang and Xiaotangzi formations. The gases reservoired in the 4~(th) member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks.     

中国南方古生界-中生界油气藏成藏规律及勘探方向

中国南方古生界—中生界古油藏主要分布于黔中—雪峰 -江南隆起北侧 (以下古生界及上震旦统灯影组古油藏为主 ,其烃源主要是下寒武统 )及南盘江—十万大山地区上古生界及下三叠统台地及孤立台地边缘 (主要是上古生界及下三叠统自生自储型古油藏 ) ;现存古生界—中生界油气藏主要分布于四川盆地。根据南方多期构造改造及油气演化复杂性的特点 ,将南方古生界—中生界油气藏分成原生、次生及再生烃油气藏 3类。认为南方现存的古生界—中生界原生油气藏很少 ,绝大部分原生油气藏均已破坏成为古油藏 ,四川盆地现存的大多数油气藏是典型的次生油气藏。提出次生气藏有利勘探领域有川东南及大巴山前缘上石炭统—下三叠统、乐山 -龙女寺隆起东南斜坡上震旦统灯影组及下古生界、川西北地区及楚雄盆地北部凹陷上三叠统—下侏罗统煤成气藏 ,再生烃油气藏有利勘探地区有苏北盆地阜宁—盐城—海安—兴化—宝应地区、江汉盆地沉湖地区南部潜江—仙桃—牌州—汊参 1井地区及江西鄱阳盆地南部凹陷。这一认识已经得到苏北盆地盐城凹陷朱家墩气田、川东方斗山背斜带寨沟湾石炭系气田及江汉盆地沉湖地区南部开先台西油藏勘探发现的证实。     

北黄海盆地东部坳陷中生界烃源岩特征及其指示的油气勘探方向

为了量化表征北黄海盆地东部坳陷中生界主力烃源岩生、排烃特征,综合利用镜质体反射率(R_o)、残余有机碳含量(TOC)、岩石热解、干酪根镜检及饱和烃色谱等资料,在总结研究区烃源岩地化特征的基础上,通过油源对比明确主力烃源岩层并依托盆地模拟方法量化其生、排烃贡献.结果表明,北黄海盆地东部坳陷中生界的两类原油均来源于区内中侏罗统和上侏罗统两套主力烃源岩层,其中,中侏罗统烃源岩的有机质丰度整体处于"好-最好"级别,上侏罗统烃源岩的有机质丰度则以"中等-好"为主;二者均存在早白垩世末期和早中新世两次生、排烃高峰,但上侏罗统的排烃速率[q_e(max)=27.3×106 t/Ma]远高于中侏罗统的排烃速率[q_e(max)=4.2×106 t/Ma],对研究区油气成藏的贡献更大.虽然下白垩统暗色泥岩的生烃潜力有限,但其底部砂岩与紧邻上侏罗统主力烃源岩层构成的"下生上储"式的源储配置关系是区内最重要的勘探目的层,其次为中、上侏罗统内部"自生自储"式的有利成藏组合,同时,中侏罗统下部"上生下储"式的成藏组合也应予以重视.      

川西坳陷中段新场地区天然气研究及气源对比

经过大量学者多年的研究总结,川西坳陷中段新场地区具备良好的生、储、盖等成藏组合。结合地质背景及碳同位素、轻烃的研究,认为新场地区天然气主要是Ⅲ型干酪根的煤型气,气藏主要分布在上三叠系的须二段和须四段,以及中侏罗系、上侏罗系地层中。     

Gas generation and expulsion characteristics of Middle–Upper Triassic source rocks,eastern Kuqa Depression,Tarim Basin,China: implications for shale gas resource potential

Frontier exploration in the Kuqa Depression, western China, has identified the continuous tight-sand gas accumulation in the Lower Cretaceous and Lower Jurassic as a major unconventional gas pool. However, assessment of the shale gas resource in the Kuqa Depression is new. The shale succession in the Middle–Upper Triassic comprises the Taliqike Formation (T₃t), the Huangshanjie Formation (T₃h) and the middle–upper Karamay Formation (T_2–3k), with an average accumulated thickness of 260 m. The high-quality shale is dominated by type III kerogen with high maturity and an average original total organic carbon (TOC) of about 2.68 wt%. An improved hydrocarbon generation and expulsion model was applied to this self-contained source–reservoir system to reveal the gas generation and expulsion (intensity, efficiency and volume) characteristics of Middle–Upper Triassic source rocks. The maximum volume of shale gas in the source rocks was obtained by determining the difference between generation and expulsion volumes. The results indicate that source rocks reached the hydrocarbon expulsion threshold of 1.1% VR and the hydrocarbon generation and expulsion reached their peak at 1.0% VR and 1.28% VR, with the maximum rate of 56 mg HC/0.1% TOC and 62.8 mg HC/0.1% TOC, respectively. The volumes of gas generation and expulsion from Middle–Upper Triassic source rocks were 12.02 × 10¹² m³ and 5.98 × 10¹² m³, respectively, with the residual volume of 6.04 × 10¹² m³, giving an average gas expulsion efficiency of 44.38% and retention efficiency of 55.62%. Based on the gas generation and expulsion characteristics, the predicted shale gas potential volume is 6.04 × 10¹² m³, indicating a significant shale gas resource in the Middle–Upper Triassic in the eastern Kuqa Depression.     

Source Rocks for the Giant Puguang Gas Field,Sichuan Basin:Implication for Petroleum Exploration in Marine Sequences in South China

Detailed geochemistry studies were conducted to investigate the origin of solid bitumens and hydrocarbon gases in the giant Puguang gas field. Two types of solid bitumens were recognized： low sulfur content, low reflectance （LSLR） solid bitumens in sandstone reservoirs in the Xujiahe Formation and high sulfur content, high reflectance （HSHR） solid bitumens in the carbonate reservoirs in the Lower Triassic Feixianguan and Upper Permian Changxing formations. Solid bitumens in the Upper Triassic Xujiahe Formation correlate well with extracts from the Upper Triassic to Jurassic nonmarine source rocks in isotopic composition of the saturated and aromatic fractions and biomarker distribution. Solid bitumens in the Feixianguan and Changxing formations are distinctly different from extracts from the Cambrian and Silurian rocks but display reasonable correlation with extracts from the Upper Permian source rocks both in isotopic composition of the saturated and aromatic fractions and in biomarker distribution, suggesting that the Permian especially the Upper Permian Longtan Formation was the main source of solid bitumens in the carbonate reservoirs in the Feixianguan and Changxing formations in the Puguang gas field. Chemical and isotopic composition of natural gases indicates that the majority of hydrocarbon gases originated from sapropelic organic matter and was the products of thermal cracking of accumulated oils. This study indicates that source rock dominated by sapropelic organic matter existed in the Upper Permian and had made major contribution to the giant Puguang gas field, which has important implication for petroleum exploration in marine sequences in South China.     

Petroleum geology and exploration direction of gas province in deepwater area of North Carnarvon Basin,Australia

North Carnarvon Basin is a gas province with minor oily sweet spots in deepwater area with water depth more than 500 m, which is one of the hot spots of global petroleum exploration for its series of giant hydrocarbon discoveries in recent years. However, the degree of oil and gas exploration in deepwater area is still low, and the conditions for oil and gas accumulation are not clear. Based on the current exploration situation and latest database of fields, applying multidisciplinary analysis of hydrocarbon geology, hydrocarbon accumulation elements and its exploration direction of North Carnarvon Basin in deepwater area are analyzed. The results show that there are three sets of main source rocks in deepwater area of North Carnarvon Basin, which are Triassic marine shale in Locker Formation and delta coal-bearing mudstone with thin carbonaceous mudstone in Mungaroo Formation, Lower –Middle Jurassic paralic carbargilite and coal measure strata in Athol Formation and Murat Formation, Cretaceous delta mudstone in Barrow Group and marine shale in Muderong Formation. Most source rock samples show gas-prone capability. The coarse sandstone of delta facies in Middle–Upper Triassic Mungaroo Formation is the most important reservoir in deepwater area, Lower Cretaceous Barrow Group deep-water gravity flow or underwater fan turbidite sandstone is the secondly main reservoir. Lower Cretaceous marine shale in Muderong Formation is most important regional caprock. Triassic mudstone in Mungaroo Formation is an important interlayer caprock in deepwater area. There are two main reservoir accumulation assemblages in deepwater area, one is Triassic structural-unconformity plane reservoir accumulation assemblage of Locker Formation to Mungaroo Formation, and the other is Lower–Middle Jurassic Athol Formation and Murat Formation–Lower Cretaceous stratigraphic lithology-structural reservoir accumulation assemblage of Barrow Group to Muderong Formation. There are three main control factors of hydrocarbon Accumulation: One is coupling of source and seal control hydrocarbon distribution area, the second is multi-stage large wave dominated deltas dominate accumulation zone, the third is direction of hydrocarbon migration and accumulation in hydrocarbon-rich generation depression was controlled by overpressure. The south of Exmouth platform in deepwater area is adjacent to hydrocarbon rich depression zone, reservoir assemblage is characterized by “near source rocks, excellent reservoir facies, high position and excellent caprocks ”, which is the main battlefield of deepwater oil and gas exploration in North Carnarvon Basin at present. There are a lot of fault block traps in the northern structural belt of Exmouth platform, and the favorable sedimentary facies belt at the far end of delta plain in Mungaroo Formation is widely distributed, which is the next favorable exploration zone. The Lower Cretaceous, which is located at the concave edge uplift adjacent to the investigator depression and the Exmouth platform, also has a certain exploration prospect in northwest of deepwater area.