鄂尔多斯北部杭锦旗探区上古生界烃源岩评价

鄂尔多斯盆地北部杭锦旗探区上古生界烃源岩问题争议大。通过有机地球化学分析、盆地模拟等方法手段对研究区上古生界烃源岩展开研究。结果表明,上古生界发育石炭系、二叠系两套烃源岩,煤层是最好的烃源岩,泥岩为差烃源岩。煤层有机碳的质量分数最高,平均值为61.32%;有机质类型好,以Ⅲ型干酪根为主,属于生气型源岩;有机质成熟度为0.8%~1.3%,已经进入生气高峰阶段。烃源岩生气强度为(0.1~1.3)×109m3/km2,具备为研究区天然气成藏提供物质基础的条件。盆地模拟结果表明山西组总生气量大于太原组,是主要的烃源岩层系。烃源岩从侏罗纪末进入大规模生烃阶段,生烃高峰为早白垩世。研究区石炭系和二叠系煤层是上古生界天然气成藏的主要气源岩,天然气组分中甲烷含量变化、天然气侧向运移距离等证据进一步佐证了上述观点,突出了研究区上古生界烃源岩的原地性特征。     

鄂尔多斯盆地东南部奥陶系烃源岩评价

鄂尔多斯盆地东南部奥陶系地层烃源岩厚度大,类型多种多样,成熟度高,为了客观认识鄂尔多斯盆地东南部奥陶系地层烃源岩有机质丰度和生烃潜力,通过有机岩石学和有机地球化学相互结合综合分析的方法开展对鄂尔多斯盆地东南部地区奥陶系烃源岩评价研究。结果表明:鄂尔多斯盆地东南部奥陶系发育泥质烃源岩和碳酸盐岩烃源岩,其主要分布在南缘古坳陷和陕北古坳陷;烃源岩残余有机碳平均值0.30%~3.12%;有机质类型主要为Ⅰ-Ⅱ_1型;烃源岩热演化程度达到高成熟-过成熟阶段;奥陶系烃源岩在三叠系朱(T_3y末)进入生气高峰,至侏罗系末(J末)属持续埋藏生气阶段,从晚白垩世开始抬升隆起,生气强度逐渐降低。综合区域地质分析认为,渭北隆起北部与伊陕斜坡南部过渡带在晚古生代沉积后,奥陶系烃源岩埋深一般大于2500 m,生气时间长,有利于天然气形成,是有利的勘探目标区。     

准连续型致密砂岩气藏地质条件和成藏特征——以鄂尔多斯盆地中部上古生界山西组为例

通过大量钻井、测井、录井以及试气资料,结合岩心观察和薄片鉴定,对鄂尔多斯盆地上古生界山西组准连续型致密砂岩储层的岩石学特征、成岩作用、物性特征和孔候特征进行综合分析,并对山西组的成藏特征从烃源岩特征、储层特征、储盖组合特征以及成藏模式4个方面进行研究.结果表明:鄂尔多斯盆地上古生界山西组属于准连续型致密砂岩气藏,烃源岩在早白垩世末大量生气,具有近源成藏、砂体大面积准连续分布、储层致密、成岩作用类型多、孔喉结构复杂、物性普遍较差、烃源岩类型好等特征.山西组下部主要广覆式发育优质烃源岩,上部主要为致密储层,天然气通过微裂缝进入致密储层中进而成藏,在地层中呈准连续分布.综合分析鄂尔多斯盆地上古生界山西组准连续型致密砂岩气资源潜力大,具有广阔的勘探前景.     

四川威远震旦系与下古生界天然气成藏特征

四川盆地威远气田是唯一的在震旦系灯影组、寒武系洗象池组和奥陶系宝塔组均获得气藏和气井的地区.通过对比威远气田震旦系、寒武系和奥陶系天然气成分特征,得出奥陶系天然气与震旦-寒武系特征存在差异,暗示是两套不同的烃源体系,前者主要供烃来源是下志留统,后者供烃来源主要是下寒武统.但威远气田寒武系和奥陶系储集性能先天不好,加之加里东期构造抬升剥蚀破坏了保存条件,制约了天然气的大规模成藏.在此基础上,通过对四川盆地下组合的几个重点勘探地区威远-资阳-安平店、高石梯-丁山构造震旦系天然气成藏条件的对比分析,在烃源、盖层和储集层条件相似的情况下对应的最终成藏结果却不同,这与前期古油气藏的分布有关,也与后期隆升构造调整有关,这些都是制约震旦系的成藏关键,也说明四川盆地震旦系与下古生界(下组合)勘探的苛刻性和复杂性.     

鄂尔多斯盆地西北部奥陶系“三元”主控成藏规律

通过对鄂尔多斯盆地西北部奥陶系烃源岩、储集层及天然气展布规律的研究,探讨其天然气成藏规律。奥陶系烃源岩主要分布在上统乌拉力克组和拉什仲组,以海相泥岩为主;储层主要发育在中统克里摩里组和桌子山组,依据岩石类型、孔隙结构,可分为岩溶孔洞型储层和白云岩晶间溶孔型储层;天然气藏的形成受烃源岩、储层和圈闭的"三元"主控,具有有效烃源岩控制天然气区域分布、优质储层控制天然气聚集带展布、有效圈闭控制气藏分布特征。鄂尔多斯盆地西北部的西侧气藏主要为油型气,东侧主要为煤型气,均为上生下储的成藏模式。     

鄂尔多斯盆地上古生界致密砂岩气成藏特征

鄂尔多斯盆地上古生界气藏为致密砂岩气藏。通过对盆地上古生界烃源岩、储集层、储层致密和成藏时间以及天然气运聚的分析,详细研究盆地上古生界致密砂岩气藏的成藏特征。本溪组-山西组煤层是主要的烃源岩,烃源岩有机质丰度高,干烙根为Ⅲ型干烙根,有机质成熟度高,以高-过成熟为主,为盆地天然气成藏提供充足的物质基础。储层岩性以岩屑石英砂岩、石英砂岩和岩屑砂岩为主,孔隙度主要分布在4%~8%,渗透率在0.1×10~(-3)~0.5×10~(-3)μm~2,为低孔低渗致密砂岩储层。储层具有"小孔隙、细喉道、微裂缝不发育、孔喉连通性差"的特点。致密气藏是先致密后成藏,储层在早-中侏罗世储层演化为致密砂岩储层;而后在晚侏罗世-早白垩世天然气大量充注形成气藏。天然气在气体膨胀力的作用下沿着微裂缝近距离运移聚集形成大面积连片分布的致密砂岩气藏。     

天然气运移理论对我国天然气地质学建立的重要贡献

近 2 0年来 ,天然气运移理论研究对我国天然气地质学发展的贡献可概括为①为多源、多阶段和多运移相态天然气成藏理论的建立提供了重要依据 ;②进一步阐述了天然气成藏过程 ,指出天然气运移地质条件是盆地、热作用和成烃演化成藏三大地质要素的有机结合 ,是促进天然气聚集成藏的关键 ;③建立了天然气动态成藏、多期成藏和晚期成藏理论 ;④建立了符合中国地质特点的天然气调查研究系列的重要依据 ;⑤根据天然气运移理论 ,总结了中国大中型气田成藏条件 ,明确了中国大中型气田的勘探方向     

陕北斜坡东部上古生界烃源岩地球化学特征

陕北斜坡东部是鄂尔多斯盆地新发现的天然气富集区,通过综合剖析天然气地球化学特征和烃源岩的展布特征、地球化学特征,对该区烃源岩进行探究。研究后认为:1该区天然气具有甲烷含量高、非烃气体含量低的特点,气藏的重烃含量不高,干燥系数较高,气藏偏干。2煤层是上古生界天然气贡献最大的源岩,泥岩是天然气的第二位供应者,其中山西组泥岩为中等—好的烃源岩,太原组泥岩为好—非常好的烃源岩,本溪组泥岩属于好—极好的烃源岩。3该区上古生界煤系烃源岩母质输入具有多元性,有机质类型以腐殖型为主,Ro普遍高于2.0%,已进入过成熟干气阶段。     

鄂尔多斯盆地上古生界天然气成藏的地质特征

总结了天然气成藏的地质特征，目的是预测盆地内有利的天然气勘探区块。综合采用野外露头观察、钻井岩芯观察和室内分析研究等方法。研究表明，盆地晚古生代多种沉积体系发育，奠定了气藏的物质基础；沉积层序的演化控制了气源岩、储集层和盖层的发育及其空间组合；持续供气的气源岩、大范围分布的致密砂岩储集层、多因素封盖、就近成藏和成藏期晚等因素的综合作用有利于鄂尔多斯盆地上古生界天然气藏的形成和保存。指出盆地内5个有利的天然气勘探区块。     

鄂尔多斯盆地东缘临兴地区上古生界烃源岩特征及其对天然气成藏的控制作用

应用测井、录井、岩心等资料确定鄂尔多斯盆地东缘临兴地区上古生界烃源岩展布特征,通过有机质丰度、类型、成熟度指标对烃源岩进行综合评价,并分析了烃源岩条件对气藏形成与分布的控制作用。研究表明,临兴地区上古生界烃源岩为山西组、太原组和本溪组的煤层及暗色泥岩,其中主力烃源岩为煤层。煤层厚度2. 17～31. 01 m,均值18. 91 m;暗色泥岩厚度16. 93～119. 95 m,均值59. 19 m。烃源岩有机质丰度较高,煤的残余有机碳20. 40%～87. 32%,均值62. 15%,暗色泥岩的残余有机碳0. 09%～38. 60%,均值4. 59%;有机质类型以Ⅲ型干酪根为主,含有部分Ⅱ型干酪根;受紫金山岩体侵入的影响,烃源岩成熟度较高,烃源岩镜质体反射率0. 78%～4. 89%,均值1. 23%,主体处于成熟—高成熟阶段。临兴地区生气强度(10. 22～44. 86)×108m3/km2,与邻区神木气田(生气强度(8～33)×108m3/km2)相比,临兴地区的气源条件优于神木气田。平面上,临兴地区内煤层厚度 11 m,生气强度 11×108m3/km2的区域为工业气流井主要分布区,且在烃源岩条件较好的区域,其含气性也较高;纵向上,天然气垂向运移距离与煤层厚度和生气强度具有一定的正相关性,表现为随煤层厚度、生气强度增大,天然气垂向运移距离更远。     

鄂尔多斯盆地中部奥陶系风化壳天然气的运移特征

鄂尔多斯盆地中部奥陶系风化壳天然气运移是迄今研究比较薄弱的重要问题 .在前人工作的基础上 ,依据实际的地质和地球化学资料 ,分析了鄂尔多斯盆地中部奥陶系风化壳天然气的运移特征 .研究认为 ,以靖边为中心的中部气区是天然气运移的有利区 .奥陶系风化壳天然气的运移较为复杂 ,既有奥陶系来源天然气的侧向运移 ,又有上覆石炭—二叠系来源天然气的穿层运移 .这与研究区的构造演化、古流体等研究结果相吻合     

Features of the type Ⅲ-like source rock and its generated natural gas

The mother matter of Ordovician source are mainly sapropelic and generate oil in mature stage, since the high plants did not appear in Ordovician period, which is well known by internal and external scholars. Now we find a kind of Orodovician source rock generating mainly light oil and gas in mature stage during appraising source rocks in the Tarim Basin. The organic matters of this source rock are chiefly constructed by benthic brown algae in organisms (showing as macro algae), and are similar to humic source in hydrocarbon generation. The natural gas generated by this kind of source matters is obviously different from the sapropelic gas.     

Features of the type III-like source rock and its generated natural gas

The mother matter of Ordovician source are mainly sapropelic and generate oil in mature stage, since the high plants did not appear in Ordovician period, which is well known by internal and external scholars. Now we find a kind of Orodovician source rock generating mainly light oil and gas in mature stage during appraising source rocks in the Tarim Basin. The organic matters of this source rock are chiefly constructed by benthic brown algae in organisms (showing as macro algae), and are similar to humic source in hydrocarbon generation. The natural gas generated by this kind of source matters is obviously different from the sapropelic gas.     

Dynamics for multistage pool formation of Lunnan low uplift in Tarim Basin

Lunnan area in the Tarim Basin has become animportant onshore oil production base in China. Formationof the oil and gas pools in the low uplift of Lunnan has ex-perienced a comparatively complex process of dynamics.Based on the hydrocarbon generation period of source rocks,the formation period of cap rocks and traps, the analysis oforganic inclusion and the analysis of bitumen in the reservoir,this paper draws the conclusion that the low uplift area ofLunnan has experienced three pool formation periods: thePermian period, the Cretaceous-Early Tertiary period andthe Late Tertiary-Quaternary period and two oil and gasreservoir adjustment periods: the Late Permian period andthe Late Tertiary-Quaternary period. The comprehensivestudy indicates that the large-scale Ordovician buried hill,formed in Early Hercynian, became the reservoir during thePermian period, because the Cambrian-Lower Ordovicianoil was discharged laterally into the reservoir along the topof the Ordovician weathering crust from south to north. Thereservoir experienced a complicated process—reconstruc-tion in the end of Permian, adjustment in Cretaceous-EarlyTertiary and re-discharging process in Late Tertiary-Qua-ternary, leading to the early original heavy oil reservoir ofmarine facies and the late original light oil reservoir and gaspool. Carboniferous, Triassic and Jurassic oil and gas reser-voirs result from upward adjustment and re-distribution ofOrdovician oil and gas reservoirs. Of those results, the for-mation of Triassic-Jurassic oil and gas pools came under theinfluence of the northward-tilting structure. The oil and gassourcing from the different hydrocarbon source rock inter-vals vertically migrated into the base unconformity of Trias-sic system. Then the oil and gas migrated laterally fromnorth to south and accumulated into the reservoir.     

An approach to noble-gas isotopic compositions in natural gases and gas-source tracing in the Ordos Basin, China

Isotopic compositions of noble gases, i.e. He Ar Kr and Xe, are measured in natural gases from the Zhongbu gasfield in the Ordos Basin. And heavy noble-gas isotopes (Kr, Xe) are here first used in geochemically studying natural gases and gas-source correlation. Isotopic compositions of heavy noble gases in natural gases, especially Xe, show two-source mixing in the Zhongbu gasfield. Gas sources are somewhat different in the northeast and the southwest of the gasfield. Generally, the gas source of the Lower Paleozoic makes a greater contribution in the southwest than in the northeast in the field. Two kinds of gases can be differentiated from isotopic compositions of heavy noble gases and from their relation with the Ar isotopic composition, Therefore, the comprehensive study on isotopic compositions of light and heavy noble gases can supply more useful information on gas-source correlation and tracing.     

塔中地区油气资源评价

系统评价了塔里木盆地塔中地区的烃源岩,采用盆地数值模拟方法定量计算了塔中地区的生、排烃数量。研究表明,塔中地区的油气运移聚集主要发生于早古生代和晚古生代的几次构造运动期间,聚集的油气曾遭受过严重的破坏,塔中地区的构造演化对塔中地区的油气聚集起着至关重要的作用。寒武系和下奥陶统烃源岩生排油时间较早,因此对现今已发现的油藏贡献不大,而晚排出的天然气有利于聚集;中上奥陶统烃源岩生排油延续时间较长,对塔中的油气聚集有实质性的贡献。     

鄂尔多斯盆地北部上古生界煤成气及其砂岩气藏成藏模式

鄂尔多斯盆地北部上古生界地层中广泛发育的煤层是大型气田形成的物质基础,煤层埋深为2.2~2.8 km,厚度为22~49 m,镜质体反射率为0.6%~2.5%,属长焰煤—贫煤;煤层是良好的烃源岩,其平均生烃强度为23.52×108m3/km2.煤层、砂岩储层和顶部上石盒子区域性泥岩盖层的良好空间配置是上古生界煤成气砂岩气藏形成的关键.描述了该地区上古生界砂岩和泥岩中2种高角度裂缝特征,指出了裂缝的形成时期及其在煤成气成藏中的运移通道作用.最后将该地区煤成气藏近源型成藏模式细分为近源-源内聚集型和近源-裂缝运移型.     

Two accumulation modes of marine-origin natural gas in the Tarim Basin

HeUanhe gas field, Lungudong gas field and Tazhong gas field are marine marine-origin natural gas reservoirs in the craton area in the Tarim Basin. The natural gas is generated from Cambrian source rocks. The simulation experiment indicated that the cracking of the dispersedly dissoluble organic matter remaining in the source rocks is the main origin of marine natural gas. There are two modes to form gas reservoirs, one is the dry gas reservoir such as HeUanhe gas field, in which gas accumulated on the fault belt with violent tectonic movement, the other is condensate gas reservoir formed on the inheriting uplift such as Lunnan and Tazhong gas fields. The hybrid simulation experiment of cracking gas and crude oil indicated that crude oil accumulated on a large scale in those uplift belts at the early stage, and natural gas filled the ancient oil reservoir at the late stage, and the gas reservoirs were formed after the gas mixed with the crude oil.     

The generation and accumulation of natural gas from Yinan 2 gas pool in Kuqa Depression

By using the methods of hydrocarbon generation kinetics and carbon isotope kinetics, combined with geological background of natural gas pool formation, the generation and accumulation of natural gas from Yinan 2 gas pool was studied in Kuqa Depression of the Tarim Basin. Natural gas of Yinan 2 gas pool is mainly derived from Middle and Lower Jurassic coal-bearing source rocks, and generally belongs to long time-accumulated gas. It is suggested that Yinan 2 gas is chiefly accumulated in the last 5 Ma, its Ro ranges from 1.25% to 1.95%, and the loss rate of natural gas is about 25%-30%. This work not only complements and reduces the deficiency of formation model of natural gas pools which traditionally depends on the matching relationships between source rock, reservoir, cap rock, and trap, but also is a useful reference in the study of other gas pools.