我最新的文章“Depletion of 13C in residual ethane and propane during thermal decomposition in sedimentary basins”(沉积盆地乙烷和丙烷分解过程中13C的贫化)终告发表,发表于Organic Geochemistry杂志,今天收到了50天免费下载的链接: https://authors.elsevier.com/a/1Xm4ZXLtI-T0e 这篇文章,看起来只是解决一个问题,但实际上回答了天然气成因的国内外三个或者四个大问题。 一个问题是页岩气高成熟阶段的乙烷和丙烷同位素倒转,即,随成熟度增加,乙烷和丙烷更加贫13C。这和通常的动力学分馏相反。这个问题是在10年前,随着巴奈特页岩气的开发,开始引人注意的。之后研究人员发表了很多文章试图来解释这个问题,惭愧的是我2013年在Chemical Geology上也发了一篇,认为“干酪根裂解气”和“油裂解气”混合是造成同位素异常的原因。但我随后在Hess工作时就发现,这种混合不符合高成熟阶段烃源岩内的物料平衡。遗憾的是这篇文章已经误导了很多研究者。 另一个问题是鄂尔多斯盆地奥陶系天然气的气源。这些天然气碳同位素的特征,实际和后来的巴奈特页岩气很相似。因为乙烷很贫13C,按照通常的天然气划分指标,就归结为海相碳酸盐岩气;于是,奥陶系气藏的天然气被认为贫有机质碳酸盐岩形成的。这又涉及到国内一个更大的问题,即,中国广泛分布的古生界贫有机质碳酸盐岩是不是烃源岩?从物料平衡、石油地质分析、国内外油气藏对比等多个角度考虑,这种贫有机质碳酸盐岩不会成为油气藏的源岩。那么,乙烷的天然气特征必须重新解释。 最后一个问题就是无机成因天然气的问题。上面说的是乙烷丙烷随母质成熟度而贫13C,这是一种倒转;另一种倒转是甲烷、乙烷和丙烷依次更贫13C。后面一种倒转,长期被认为是费托反应合成天然气的特征。松辽盆地1990年代中期发现了这种特征的天然气,所以一直被认为地球深部费托反应合成的,也就是无机成因天然气,或者“非生物成因天然气”。但是地质证据不支持这些天然气是深部来源的。此外,甲烷、乙烷和丙烷的13C倒转,在高成熟页岩气中也发现得越来越多。 我们的文章,说明的是,如果乙烷和丙烷分解是部分可逆的,那么残留的乙烷和丙烷就可以变得贫13C。所以上面种种现象,其实都是在高成熟阶段,乙烷丙烷部分可逆分解造成的结果。 同行肯定知道这篇文章的重要程度,所以最先投往GCA。但是GCA始终建议改投,即使争取到送审、审稿人同意修改发表之后,编辑部依然要求改投。不过,在我最近多读了GCA的一些参考文章之后,发现这篇文章简洁得有些单薄,确实不符合GCA的口味。 无论如何,困扰二十多年的学术问题,终于有了简明的答案。我刚把文章链接用邮件发给了一下石油地球化学同行,一位同行的评价是,我现在的解释“quite eloquent”。这也是我最感欣慰的评价。
新闻报道见此: http://www.cas.cn/xw/cmsm/201405/t20140513_4118737.shtml 《Science》编辑的总结: EDITOR'S SUMMARY Upgrading Methane Sans Oxygen Direct routes to converting methane to higher hydrocarbons can allow natural gas to be used to provide chemical feedstocks. However, the reaction conditions needed to activate the strong C-H bond tend to overoxidize the products. Guo et al. (p. 616) report a high-temperature nonoxidative route that exposes methane to isolated iron sites on a silica catalyst. Methyl radicals were generated and coupled in the gas phase to form ethylene and aromatics along with hydrogen. The isolation of the active sites avoided surface reactions between the radicals that would deposit solid carbon. 补充材料有对催化剂合成和反应的描述: http://www.sciencemag.org/content/suppl/2014/05/07/344.6184.616.DC1/Guo.SM.pdf 文章让人很兴奋,如果这个技术真的产业化了,对天然气的利用绝对是革命性的突破。但是冷静下来可以想到这么好的技术或许不会先发paper,所以不禁还是有些疑问,这些疑 问是: 一、只要催化剂中没有成簇的金属,就可以防止积碳?实际情况不是如此。现在在线测量甲烷氢同位素的方法是把甲烷在1350摄氏度(比这篇文章的反应温度高之有限)的活性炭上彻底分解为氢气和碳;而活性炭是担载在氧化铝上面,这个反应并不需要金属催化。 二、乙烯是个热力学很不稳定的物质,高温下远远比甲烷容易分解为石墨和氢气,而且 乙烯更容易和自由基反应 。感觉上 乙烯应该是浓度很低的暂态产物, 但是产物中 乙烯浓度很高。 补充材料页5中把 乙烷作为中间体,而产物中并没有乙烷的选择性,很让人费解。这些结果无论 从热力学还是动力学上都不好理解。 三、如果产物中有少量积碳,如何能够定量。 所以目前对这个潜在技术至多只能谨慎乐观,如果能走到中试,或许会回答上面问题。
2010年美国墨西哥湾深海油气井泄漏事件想毕大家还记忆犹新。其实这类灾害与深海油气井在海底建造的天然气水合物有关。最近MIT科学家研究出抑制深海油气井甲烷水合物建造的表面涂层,值得我们关注。( http://web.mit.edu/newsoffice/2012/undersea-ice-clog-mitigation-0412.html ) During the massive oil spill from the ruptured Deepwater Horizon well in 2010, it seemed at first like there might be a quick fix: a containment dome lowered onto the broken pipe to capture the flow so it could be pumped to the surface and disposed of properly. But that attempt quickly failed, because the dome almost instantly became clogged with frozen methane hydrate. Methane hydrates, which can freeze upon contact with cold water in the deep ocean, are a chronic problem for deep-sea oil and gas wells. Sometimes these frozen hydrates form inside the well casing, where they can restrict or even block the flow, at enormous cost to the well operators. Now researchers at MIT, led by associate professor of mechanical engineering Kripa Varanasi, say they have found a solution, described recently in the journal Physical Chemistry Chemical Physics . The paper’s lead author is J. David Smith, a graduate student in mechanical engineering. The deep sea is becoming “a key source” of new oil and gas wells, Varanasi says, as the world’s energy demands continue to increase rapidly. But one of the crucial issues in making these deep wells viable is “flow assurance”: finding ways to avoid the buildup of methane hydrates. Presently, this is done primarily through the use of expensive heating systems or chemical additives. “The oil and gas industries currently spend at least $200 million a year just on chemicals” to prevent such buildups, Varanasi says; industry sources say the total figure for prevention and lost production due to hydrates could be in the billions. His team’s new method would instead use passive coatings on the insides of the pipes that are designed to prevent the hydrates from adhering. These hydrates form a cage-like crystalline structure, called clathrate, in which molecules of methane are trapped in a lattice of water molecules. Although they look like ordinary ice, methane hydrates form only under very high pressure: in deep waters or beneath the seafloor, Smith says. By some estimates, the total amount of methane (the main ingredient of natural gas) contained in the world’s seafloor clathrates greatly exceeds the total known reserves of all other fossil fuels combined. Inside the pipes that carry oil or gas from the depths, methane hydrates can attach to the inner walls — much like plaque building up inside the body’s arteries — and, in some cases, eventually block the flow entirely. Blockages can happen without warning, and in severe cases require the blocked section of pipe to be cut out and replaced, resulting in long shutdowns of production. Present prevention efforts include expensive heating or insulation of the pipes or additives such as methanol dumped into the flow of gas or oil. “Methanol is a good inhibitor,” Varanasi says, but is “very environmentally unfriendly” if it escapes. Varanasi’s research group began looking into the problem before the Deepwater Horizon spill in the Gulf of Mexico. The group has long focused on ways of preventing the buildup of ordinary ice — such as on airplane wings — and on the creation of superhydrophobic surfaces, which prevent water droplets from adhering to a surface. So Varanasi decided to explore the potential for creating what he calls “hydrate-phobic” surfaces to prevent hydrates from adhering tightly to pipe walls. Because methane hydrates themselves are dangerous, the researchers worked mostly with a model clathrate hydrate system that exhibits similar properties. The study produced several significant results: First, by using a simple coating, Varanasi and his colleagues were able to reduce hydrate adhesion in the pipe to one-quarter of the amount on untreated surfaces. Second, the test system they devised provides a simple and inexpensive way of searching for even more effective inhibitors. Finally, the researchers also found a strong correlation between the “hydrate-phobic” properties of a surface and its wettability — a measure of how well liquid spreads on the surface. The basic findings also apply to other adhesive solids, Varanasi says — for example, solder adhering to a circuit board, or calcite deposits inside plumbing lines — so the same testing methods could be used to screen coatings for a wide variety of commercial and industrial processes. Richard Camilli, an associate scientist in applied ocean physics and engineering at Woods Hole Oceanographic Institution who was not involved in this study, says, “The energy industry has been grappling with safety and flow-assurance issues relating to hydrate formation and blockage for nearly a century.” He adds that the issue is becoming more significant as drilling progresses into ever-deeper water and says the work by Varanasi’s team “is a big step forward toward finding more environmentally friendly ways to prevent hydrate obstruction in pipes.” The research team included MIT postdoc Adam Meuler and undergraduate Harrison Bralower; professor of mechanical engineering Gareth McKinley; St. Laurent Professor of Chemical Engineering Robert Cohen; and Siva Subramanian and Rama Venkatesan, two researchers from Chevron Energy Technology Company. The work was funded by the MIT Energy Initiative-Chevron program and Varanasi’s Doherty Chair in Ocean Utilization. A block of a gas hydrate (methane clathrate) recovered from seafloor sediments off the Oregon coast. Photo: Wusel007/wikipedia
圆圈内是北极地区拥有石油和天然气资源的区域 The Arctic holds an estimated 13% (90 billion barrels) of the world's undiscovered conventional oil resources and 30% of its undiscovered conventional natural gas resources, according to an assessment conducted by the U.S. Geological Survey (USGS). Consideration of these resources as commercially viable is relatively recent despite the size of the Arctic's resources due to the difficulty and cost in developing Arctic oil and natural gas deposits. Studies on the economics of onshore oil and natural gas projects in Arctic Alaska estimate costs to develop reserves in the region can be 50-100% more than similar projects undertaken in Texas. Profitable development of Arctic oil and natural gas deposits could be challenging due to the following factors: Equipment needs to be specially designed to withstand the frigid temperatures. On Arctic lands, poor soil conditions can require additional site preparation to prevent equipment and structures from sinking. Long supply lines and limited transportation access from the world's manufacturing centers require equipment redundancy and a larger inventory of spare parts to ensure reliability, while increasing transportation costs. Employees expect higher wages and salaries to work in the isolated and inhospitable Arctic. Natural gas hydrates can pose operational problems for drilling wells in both onshore and offshore Arctic areas. Natural gas development could be especially challenging. Although the Arctic is rich in natural gas, the development of Arctic natural gas resources could be impeded by the low market value of natural gas relative to that of oil. Furthermore, natural gas consumers live far from the region, and transportation costs of natural gas are higher than those for oil and natural gas liquids. Overlapping and disputed claims of economic sovereignty between neighboring jurisdictions also could be an obstacle to developing Arctic resources. The area north of the Arctic Circle is apportioned among eight countries—Canada, Denmark (Greenland), Finland, Iceland, Norway, Russia, Sweden, and the United States. Under current international practice, countries have exclusive rights to seabed resources up to 200 miles beyond their coast, an area called an Exclusive Economic Zone (EEZ). Beyond the EEZ, assessments of "natural prolongation" of the continental shelf may influence countries' seabed boundaries. Along with economic and political challenges, environmental stewardship and regulatory permitting may also affect timelines for exploration and production of Arctic resources. Environmental issues include the preservation of animal and plant species unique to the Arctic, particularly tundra vegetation, caribou, polar bears, seals, whales, and other sea life. The adequacy of existing technology to manage offshore oil spills in an arctic environment is another unique challenge. Spills among ice floes can be much more difficult to contain and clean up than spills in open waters. The Arctic holds an estimated 13% (90 billion barrels) of the world's undiscovered conventional oil resources and 30% of its undiscovered conventional natural gas resources, according to an assessment conducted by the U.S. Geological Survey (USGS). Consideration of these resources as commercially viable is relatively recent despite the size of the Arctic's resources due to the difficulty and cost in developing Arctic oil and natural gas deposits. Studies on the economics of onshore oil and natural gas projects in Arctic Alaska estimate costs to develop reserves in the region can be 50-100% more than similar projects undertaken in Texas. Profitable development of Arctic oil and natural gas deposits could be challenging due to the following factors: Equipment needs to be specially designed to withstand the frigid temperatures. On Arctic lands, poor soil conditions can require additional site preparation to prevent equipment and structures from sinking. Long supply lines and limited transportation access from the world's manufacturing centers require equipment redundancy and a larger inventory of spare parts to ensure reliability, while increasing transportation costs. Employees expect higher wages and salaries to work in the isolated and inhospitable Arctic. Natural gas hydrates can pose operational problems for drilling wells in both onshore and offshore Arctic areas. Natural gas development could be especially challenging. Although the Arctic is rich in natural gas, the development of Arctic natural gas resources could be impeded by the low market value of natural gas relative to that of oil. Furthermore, natural gas consumers live far from the region, and transportation costs of natural gas are higher than those for oil and natural gas liquids. Overlapping and disputed claims of economic sovereignty between neighboring jurisdictions also could be an obstacle to developing Arctic resources. The area north of the Arctic Circle is apportioned among eight countries—Canada, Denmark (Greenland), Finland, Iceland, Norway, Russia, Sweden, and the United States. Under current international practice, countries have exclusive rights to seabed resources up to 200 miles beyond their coast, an area called an Exclusive Economic Zone (EEZ). Beyond the EEZ, assessments of "natural prolongation" of the continental shelf may influence countries' seabed boundaries. Along with economic and political challenges, environmental stewardship and regulatory permitting may also affect timelines for exploration and production of Arctic resources. Environmental issues include the preservation of animal and plant species unique to the Arctic, particularly tundra vegetation, caribou, polar bears, seals, whales, and other sea life. The adequacy of existing technology to manage offshore oil spills in an arctic environment is another unique challenge. Spills among ice floes can be much more difficult to contain and clean up than spills in open waters. http://www.eia.gov/todayinenergy/detail.cfm?id=4650
渤海湾盆地东营凹陷 沙四下亚段地层压力演化 与天然气成藏 刘华,沉积学报 ,2011,29(6):120-127 摘 要 :通过实测压力、泥岩声波时差、流体包裹体古压力恢复,对东营凹陷 民丰地区沙四下亚段地层压力的演化特征进行了分析。研究表明,民丰地区地层压力纵向上存在“常压 -- 超压 -- 常压”三段式结构;时间上, 沙四下亚段地层压力具有“二旋回波动模式 ” ,即存在“常压 - 弱超压 - 常压 ” 和“常压 - 超高压 - 常压(弱超压)”的演化过程,其中两次地层超压的形成时间与中深层天然气藏的两期成藏时间相对应,为油气藏的形成提供了动力条件。研究区 地层压力的动态演化过程是多因素作用的结果,第一次高压的形成是地层快速沉积产生欠压实的结果,生烃贡献相对较小;第二次超压的形成是烃源岩大量生烃和原油裂解成天然气造成的,沉积作用为辅。由于地温梯度降低、断裂 - 砂体泄压、饱和气藏深埋等作用的影响,现今民丰地区沙四下储层表现为以常压为主,伴生部分超压的分布特征。 关键词 :渤海湾盆地;东营凹陷; 裂解气;成藏动力;地层压力演化 中图分类号:TE311+.1 文献标识码 A Pressure Evolution and Gas Accumulation of the fourth member of the Shahejie Formation in Dongying depression , Bohaiwan basin Liu Hua,ACTA SEDIMENTOGICA SINICA Abstract: After the paleo-pressure build-up by means of measured pressure , mudstone sonic log interval and fluid inclusions, the pressure evolution model of the fourth member of the Shahejie formation is analyzed in Minfeng area, Dongying depression. The results show that, different periods of reservoir formation correspond to different pressure system in Es 4 reservoir, Minfeng area: the hydrocarbon accumulation of sha 2-last stage of Dongying was accomplished in a higher pressure system; the hydrocarbon accumulation environment of the last stage of Ng was normal pressure; and after the middle and late period of Nm the cracking gas in the central area of sub sag was formed in a high pressure system. The dynamic evolution process of formation pressure is the results of integrated effect of multiple factors, the first high pressure was due to uncompaction of the high-rate deposition of the formation, and the hydrocarbon-generation made a little contribution; a large amount of hydrocarbon played an important part in the form of the second high pressure, in addition the sedimentation acted as the auxiliary role. Under the influence of the decrease of geothermal gradient, fracture, sand body-pressure discharge and the deep-buried of gas reservoir, the gas reservoir founded in sha 4 reservoir, Minfeng area is mainly normal pressure. Keywords: Dongying depression; cracking gas; dynamic hydrocarbon accumulation; paleo-pressure
On October 13, 2011, Libya resumed natural gas exports to Italy via the 340-mile, Greenstream Pipeline (Greenstream), which is jointly owned by the Eni S.p.A. and the National Oil Company of Libya. Natural gas delivery imports to Sicily, Italy, at the Gela receipt point, are now about 150 million cubic feet per day (MMcf/d). http://www.eia.gov/todayinenergy/detail.cfm?id=3570
我来自山东的农村,了解农村老百姓的疾苦。尽管目前的农村,做饭的时候很多早已使用了天然气。但是看到下面一句话,还是吃惊不少。 Exposure to indoor air pollution from household burning and solid fuels affects nearly half of the world’s population. 这是最近发表在 Science 的一篇 paper 。文章以“ A Major Environmental Cause of Death ”为标题告诉了人们一个令人震惊的事实。 可以说女人在厨房遭受的环境风险因子暴露比男子吸烟还要严重,所以说 indoor air pollution 是一个值得关注的问题,因此,作为环境毒理学的科研工作者: We need both: more research trials to document rigorously the amount of reduction in IAP necessary to improve health, and also new approaches to evaluate the health benefi ts of major implementation programs already under way. Science .full.pdf
根据最新2009年统计数据表明,中东和北非国家天然气日产量占全球1/5。 In 2009 (the latest year data are available), Middle Eastern and North African (MENA) countries produced about 55 billion cubic feet per day (Bcf/d) of dry natural gas, which is about one-fifth of the estimated total worldwide daily supply and just under the average daily U.S. dry natural gas production of about 56 Bcf/d for the corresponding year. No single MENA country represented more than 5% of 2009 global dry natural gas production. Iran was the leading dry natural gas producer (12.7 Bcf/d) in MENA in 2009, a level about 20% of total 2009 U.S. natural gas consumption. MENA countries hold a much larger share of global liquefied natural gas (LNG) exports. In 2009, MENA accounted over 40% of worldwide LNG exports. Qatar's LNG exports alone reached nearly 1,800 billion cubic feet, about 20% of the global total.
网址: http://geology.geoscienceworld.org/cgi/content/abstract/39/5/451 High-precision 40 Ar/ 39 Ar age of the gas emplacement into the Songliao Basin Hua-Ning Qiu , He-Yong Wu , Jian-Bing Yun , Zi-Hui Feng , Yi-Gang Xu , Lian-Fu Mei and J.R. Wijbrans Abstract The problem of determining an exact isotopic age of hydrocarbon emplacement is complex because minerals suitable for dating with common isotopic methods are often lacking in the sedimentary domain. However, the igneous quartz from the Cretaceous volcanic rocks that host the gas reservoir in the Songliao Basin (northeastern China), contains abundant secondary fluid inclusions with high concentrations of K and high partial pressures of methane trapped during gas emplacement. Quartz with abundant K-rich fluid inclusions provides an excellent closed system well suited for 40 Ar/ 39 Ar dating. Three igneous quartz samples were measured by stepwise crushing to release the inclusion-based argon gas. All three samples yielded well-defined isochrons with ages in close agreement, precisely constraining the gas emplacement at 42.4 ± 0.5 Ma (2σ) below the Daqing oil field in the Songliao Basin, extending possible gas reservoirs from the upper Cretaceous to the middle Eocene. Received 5 November 2010. Accepted 13 December 2010. Geological So ciety of America 免费下载 HTML PDF (有效期至2013年4月): http://geology.geoscienceworld.org/cgi/content/full/39/5/451?ijkey=m3jLYm6qEV8Qskeytype=refsiteid=gsgeology ============================== 其他下载链接 http://geology.geoscienceworld.org/cgi/content/abstract/39/5/451 Full text PDF First published online March 29, 2011, doi: 10.1130/G31885.1
南京工业大学青年教师邵宗平教授,博士生张春明及合作者在国家杰出青年基金 (No.51025209) ,国家科技部 973 项目 (No.2007CB209704) 和教育部新世纪优秀人才计划的支持下在以甲烷为燃料采用进行气电共生的研究方面取得重要进展。 甲烷是天然气、煤层气和生物沼气的主要组成成分,是一种重要的能源物质和化工原料, 作者创新性地采用单室固体氧化物燃料电池结合高性能甲烷转化催化剂于同一气室中,成功实现了电能和合成气的高效共生,并实现零尾气排放。该 研究成果日前刊登于化学领域国际权威期刊德国《应用化学》上 ( Angew. Chem. Int.Ed. 2011, 50, 1792-1797) , 并被以内插图形式报道。其研究成果受到评审人的高度评价: “This is an excellent and truly exciting paper. The results are extremely interesting and would enhance the position of SOFCs as the preferred co-generation technology for practical applications...”,“This is an outstanding manuscript on the conversion of methane with oxygen to syngas and electricity…” , 两位评审人都将该研究工作的重要性选为 “Very Important” , 该论文被 德国《应用化学》选为 VIP 论文。 邵宗平 教授( 2010 年国家杰出青年基金获得者), 2005 年加入我校以来一直从事新能源材料与技术的研究,这是继其发表在国际膜科学杂志上的两篇论文相继被评为 2007 年和 2008 年度全国百篇最具影响国际学术论文以来,研究成果再次受到国内外同行的承认。 VIP paper.pdf
东营凹陷古近系天然气成藏条件及其主控因素 陈中红等 天然气工业 ,2008 ,28 (9) :9 - 12. 东营凹陷古近系深层裂解气勘探呈现出良好的态势 , 但目前对其成藏条件及其主控因素认识不清 , 因而制约了该区深层天然气的进一步勘探。对研究区大量的地球化学生烃指标、天然气组成指标及地层压力指标等进行了综合分析研究 , 结果认为东营凹陷古近系深层拥有古近系渐新统沙河街组沙三下亚段、沙四段以及古近系古新统始新统孔店组二段共计 3 套烃源岩层系 , 形成复合天然气生烃系统 , 深层裂解气形成于新近系上新统明化镇组中晚期 , 属于晚期成藏。由于沙四段中部大套膏盐岩的分割 , 古近系深层超压体系具有盐上、盐下两个次一级超压封存箱系统 , 相应形成盐上、盐下两套天然气成藏系统。各类扇体及次生孔隙是该区深层气主要的储集体及储集空间。该区沙三段中、下部沉积的深湖相灰色泥岩、油页岩 , 沙三段中上部的中厚层暗色泥岩夹钙质泥岩 , 以及沙四段中部的大套膏盐层构成了多套优质区域盖层 , 与弱的后期构造运动相互配置 , 形成良好的裂解气保存条件。古近系深层发育断层气藏、构造岩性气藏、各类沉积扇体形成的岩性气藏 , 其中后者应为该区近期深层天然气勘探的主要目标。 主题词 东营凹陷 古近纪 深层 气藏形成 勘探区 CONDITIONS AND MAIN CONTROLLING FACTORS OF NATURAL GAS POOLING IN THE PALEOGENE IN DONGYINGSAG CHEN Zhonghong et al Natural Gas Industry ,2008 ,28 (9) :9 - 12. Cracked gas exploration in the Paleogene in deep of Dongying sag is highly prospective , but current limited understandings about the cont rolling factors and conditions of gas pooling const rained further exploration of gas in deep of the sag.Analyses of the geochemical indexes of hydrocarbon - generation , gas compositions and formational pressure reveal a composite hydrocarbon generation system that is composed of three set s of source rocks in the Paleogene in deep of Dongying sag , including the lower third member , the fourth member of the Shahejie Formation and the second member of the Kongdian Formation.The deep cracked gas was generated in the middle and late stages of deposition of the Minghuazhen Formation and is characterized by late accumulation. The thick evaporates in the middle of the fourth member of the Shahejie Formation compartmentalizes the overpressure system in the Paleogene into a pre- and a post - salt compartment, resulting in a pre - and a post - salt gas system correspondingly. The reservoirs are composed mainly of various fans, while the pore space is dominated by secondary pores. The grey mudstone and oil shale in the middle and lower intervals of the third member of the Shahejie Formation, the medium to thick dark mudstone with calcareous mudstone interbeds in the upper to middle Shahejie Formation , and the thick evaporates in the middle of the fourth member of the Shahejie Formation are regional seals of high quality. These seals in combination with the weak late tectonic movement created favorable conditions for preservation of the cracked gas. Fault block gas reservoirs, st ructural 2 lithologic gas reservoirs and lithologic gas reservoirs are recognized in the Paleogene and the lithologic gas reservoirs are the major targets of deep gas exploration in the near future. Chen Zhonghong et al. Conditions and main controlling factors of natural gas pooling in the paleogene in dongying sag. Natural Gas Industry , 2008,29(9):10-14. (in Chinese)