Geological characterization and exploration potential of shale gas in the Carboniferous Jiusi Formation,northern Guizhou and Yunnan provinces,SW China

Dark mudstones and shales of the Carboniferous Jiusi Formation are widely developed in northern Guizhou and Yunnan provinces, SW China. However, the distribution, reservoir characterization, and exploration potential of organic-rich shales in this area are yet to be quantified, thus limiting the prospect of shale gas in this area. This study investigates the basic geological conditions of Jiusi shale gas, using core data, well-logs, and some other test data, obtaining the following results. The organic-rich shales are mainly composed of deltaic-to-shallow-shelf deposits, with thickness ranging from 0 to 450 m, and above 350 m around the subsidence center. The organic matter is mainly type Ⅱ kerogen with TOC content of mostly 1%–2%, indicating a moderate maturity. The argillaceous shale reservoirs are indicative of strong heterogeneity, high clay minerals content, low porosity, low permeability, high specific surface area, and relatively developed secondary porosity. The gas-log anomaly intervals obtained from the survey wells have a cumulative thickness that is apparently greater than 200 m, and a few shale intervals showing high desorbed and adsorbed gas contents. Due to complex structures in the study area, conditions responsible for shale gas occurrence and trapping are generally moderate. However, areas having wide and gentle folds with moderate depth of burial reveals relatively favorable conditions of hydrocarbon traps. In contrast with typical marine-continental transitional shales, the Jiusi shale have better geological conditions for shale gas preservation. The analysis of the geological framework and hydrocarbon potential of Carboniferous Jiusi Formation provide more insight for the exploration of Carboniferous shale gas in southern China.

Breakthrough of shallow shale gas exploration in Taiyang anticline area and its significance for resource development in Zhaotong, Yunnan Province, China

Based on exploration and development results and evaluation of marine shale gas in South China in the past ten years, in view of the features of "high maturity, strong tectonic reformation and high shear stress" of the shale in Zhaotong exploration zone in the Yunnan and Guizhou Plateau, as well as the key issues of long time diffusion and leakage of shallow shale gas, and the preservation conditions, the factors controlling shallow shale gas sweet spot and key zone selection evaluation technology of shale gas are investigated. From 2017 to 2018, the first significant exploration breakthrough was made in the Taiyang anticline at a buried depth of 700 to 2 000 m, discovering large-scale proved geological reserves of shallow shale gas. By examining the accumulation conditions and sweet spot control factors of the shallow shale gas in this area, it is found that the accumulation and productivity potential of shale gas in the mountainous area with complex structure outside basin are controlled by five factors:(1) The gas-rich area has weak tectonic reformation and good preservation conditions on the whole, taking on typical anticline trap occurrence mode.(2) The gas-rich area is in over-pressure state and high in shale gas content.(3) The gas-rich area has high quality shale and thus superior source rock condition.(4) The gas-rich area has high quality reservoirs dominated by class I.(5) The shale gas reservoir in the gas-rich area has high content of brittle minerals and small difference between maximum and minimum horizontal stresses which are conducive to hydraulic fracturing. The innovative practice and core technologies formed during the exploration and production capacity construction of shallow shale gas in the Zhaotong demonstration zone have great reference significance for shallow shale gas exploration and development in other areas.

Analysis of the world deepwater oil and gas exploration situation

The global trends in deepwater oil and gas exploration,characteristics of deepwater oil and gas discovery,and layout of deepwater oil and gas exploration business by seven major international oil companies are systematically analyzed using commercial databases(e.g.S&P Global and Rystad)and public information of oil companies.The deepwater area is currently the most important domain for global oil and gas exploration and discovery,with the most discoveries and reserves in passive continental margin basins.The deepwater discoveries have the greatest contribution to the total newly discovered oil and gas reserves in the sea areas,with an increasing number of lithological reservoirs discovered,and oil and gas discoveries mainly distributed in the Mesozoic–Cenozoic.The seven major international oil companies are widely active in various aspects of deepwater oil and gas exploration and development,and play a leading role.Based on years of theoretical understanding of global oil and gas geology and resource evaluation,it is proposed that favorable deepwater exploration areas in the future will mainly focus on three major areas:the Atlantic coast,the Indian Ocean periphery,and the Arctic Ocean periphery.Six suggestions are put forward for expanding overseas deepwater oil and gas exploration business:first,expand the sources for obtaining multi-user seismic data and improve the scientific selection of deepwater exploration areas;second,increase efforts to obtain deepwater exploration projects in key areas;third,adopt various methods to access into/exit from resource licenses flexibly;fourth,acquire licenses with large equity and operate in“dual-exploration”model;fifth,strengthen cooperation with leading international oil companies in deepwater technology;and sixth,improve business operation capabilities and gradually transform from“non-operators”to“operators”.

Analysis of the world oil and gas exploration situation in 2021

The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercial databases such as IHS and public information of oil companies. It has been found that the world oil and gas exploration situation in 2021 has continued the downturn since the outbreak of COVID-19. The investment and drilling workload decreased slightly, but the success rate of exploration wells, especially deepwater exploration wells, increased significantly, and the newly discovered reserves increased slightly compared with last year. Deep waters of the passive continental margin basins are still the leading sites for discovering conventional large and medium-sized oil and gas fields. The conventional oil and gas exploration in deep formations of onshore petroliferous basins has been keeping a good state, with tight/shale oil and gas discoveries made in Saudi Arabia, Russia, and other countries. While strengthening the exploration and development of local resources, national, international, and independent oil companies have been focusing on major overseas frontiers using their advantages, including risk exploration in deep waters and natural gas. Future favorable exploration directions in the three major frontiers, the global deep waters, deep onshore formations, and unconventional resources, have been clarified. Four suggestions are put forward for the global exploration business of Chinese oil companies: first, a farm in global deepwater frontier basins in advance through bidding at a low cost and adopt the “dual exploration model” after making large-scale discoveries;second, enter new blocks of emerging hot basins in the world through farm-in and other ways, to find large oil and gas fields quickly;third, cooperate with national oil companies of the resource host countries in the form of joint research and actively participate exploration of deep onshore formations of petroliferous basins;fourth, track tight/shale oil and gas cooperation opportunities in a few countries such as Saudi Arabia and Russia, and take advantage of mature domestic theories and technologies to farm in at an appropriate time.

Geological characteristics and development potential of transitional shale gas in the east margin of the Ordos Basin,NW China

The shales in the 2nd Member of Shanxi formation in the east margin of the Ordos Basin were deposited in a marine-nonmarine transitional environment during the Permian.Based on the recent breakthroughs in the shale gas exploration and theoretical understandings on the shale gas of the study area,with a comparison to marine shale gas in the Sichuan Basin and marine-nonmarine transitional shale gas in the U.S.,this study presents the geological characteristics and development potential of marine-nonmarine transitional gas in the study area.Four geological features are identified in the 2nd Member of the Shanxi Formation in the study area has:(1)stable sedimentary environment is conductive to deposition of widely distributed organic shale;(2)well-developed micro-and nanoscale pore and fracture systems,providing good storage capacity;(3)high content of brittle minerals such as quartz,leading to effectively reservoir fracturing;and(4)moderate reservoir pressure and relatively high gas content,allowing efficient development of shale gas.The 2nd Member of Shanxi Formation in the east margin of Ordos Basin is rich in shale gas resource.Three favorable zones,Yulin-Linxian,Shiloubei-Daning-Jixian,and Hancheng-Huangling are developed,with a total area of 1.28×104 km2 and resources between 1.8×1012 and 2.9×1012m3,indicating a huge exploration potential.Tests of the 2nd Member of Shanxi Formation in vertical wells show that the favorable intervals have stable gas production and high reserves controlled by single well,good recoverability and fracability.This shale interval has sufficient energy,stable production capacity,and good development prospects,as evidenced by systematic well testing.The east margin of the Ordos Basin has several shale intervals in the Shanxi and Taiyuan formations,and several coal seams interbedded,so collaborative production of different types of natural gas in different intervals can be considered.The study results can provide reference for shale gas exploration and development and promote the rapid exploitation of shale gas in China.

Reservoir forming conditions and key exploration and development technologies for marine shale gas fields in Fuling area, South China

Although shale gas resources are abundant in China,commercial discoveries have not been made before the discovery of Fuling Shale Gas Field.SINOPEC has done lots of theoretical and technological studies on marine shale gas development in China.Research shows shale gas has dynamic accumulations with early preservation and late reconstruction and proposes high-quality shale developed in deep-water shelf as the base and good preservation conditions as the key factor for shale gas accumulation.Key technologies and facilities were developed for geophysical survey of shale gas,design and optimization of shale gas development,drilling and completion of horizontal wells,and fracturing stimulation.As the first and largest shale gas field in China,the discovery and successful development of Fuling Shale Gas Filed has made China the first country to achieve large-scale development of shale gas after North America.By August 2017,Fuling Shale Gas Field had declared 6008.14×10^(8)m^(3) proven reserves,76.8×10^(8)m^(3) production capacity and 133.9×10^(8)m^(3) cumulative production.The construction of Fuling Shale Gas Field with high level,high speed and high quality has been a good example of shale gas development in China.Its successful experiences can be used to other fields and play an important role in optimizing energy structure and improving environment.

The Fast Road of Shale Gas Development in China——Reflections on Building a Special Test Areas for National Shale Gas Development

China's shale gas development has had a good start. It is necessary that the developers take advantage of the opportunity to make further efforts to promote shale gas development in China, in particular by rolling out a comprehensive plan on a national level. The author makes a proposal to establish a special shale gas test area in and adjacent to the Sichuan Basin as the most important way to promote the rapid development of shale gas in China. For this purpose, the author analyzes the current situation and problems of shale gas development in China, addresses the necessity and feasibility of establishing a special test area for shale gas development, and draws up the scope of this shale gas special test area of about 450 thousand square kilometers, covering Sichuan, Chongqing, Guizhou, and part of Yunnan, Hunan, Hubei provinces, and proposes the establishment of a shale gas test area in China. This consists of an overall plan, targets, and contents in 10 aspects, along with organization and implementation modes. The shale gas exploration and development in the shale gas zones is promoted vigorously by introducing special policies and innovating exploration, development and utilization model. While at the same time, the shale gas zones of continental facies in the Ordos Basin and marineterrigenous facies in South Hubei Basin will be established.The experiences of the reform in the shale gas zones will be the good practice for the reform of petroleum organization system.

Electrical structure identification of deep shale gas reservoir in complex structural area using wide field electromagnetic method

To fully exploit the technical advantages of the large-depth and high-precision artificial source electromagnetic method in the complex structure area of southern Sichuan and compensate for the shortcomings of the conventional electromagnetic method in exploration depth,precision,and accuracy,the large-depth and high-precision wide field electromagnetic method is applied to the complex structure test area of the Luochang syncline and Yuhe nose anticline in the southern Sichuan.The advantages of the wide field electromagnetic method in detecting deep,low-resistivity thin layers are demonstrated.First,on the basis of the analysis of physical property data,a geological–geoelectric model is established in the test area,and the wide field electromagnetic method is numerically simulated to analyze and evaluate the response characteristics of deep thin shale gas layers on wide field electromagnetic curves.Second,a wide field electromagnetic test is conducted in the complex structure area of southern Sichuan.After data processing and inversion imaging,apparent resistivity logging data are used for calibration to develop an apparent resistivity interpretation model suitable for the test area.On the basis of the results,the characteristics of the electrical structure change in the shallow longitudinal formation of 6 km are implemented,and the transverse electrical distribution characteristics of the deep shale gas layer are delineated.In the prediction area near the well,the subsequent data verification shows that the apparent resistivity obtained using the inversion of the wide field electromagnetic method is consistent with the trend of apparent resistivity revealed by logging,which proves that this method can effectively identify the weak response characteristics of deep shale gas formations in complex structural areas.This experiment,it is shown shows that the wide field electromagnetic method with a large depth and high precision can effectively characterize the electrical characteristics of deep,low-resistivity thin layers in complex structural areas,and a new set of low-cost evaluation technologies for shale gas target layers based on the wide field electromagnetic method is explored.

中国海相页岩气资源潜力及未来勘探方向

以中国南方上奥陶统五峰组—下志留统龙马溪组页岩气为代表的海相页岩气是国内页岩气勘探开发的主战场。近年来,海相页岩气勘探开发不断面临着新的问题和挑战,开拓页岩气资源新领域和提高页岩气产量仍是重中之重。在梳理前人研究成果的基础上,分析总结国内海相层系页岩气分布特征与资源潜力,并进行有利区预测。四川盆地及其周缘五峰组—龙马溪组页岩气地质资源量和可采资源量分别为(17.50~33.19)×10^(12)m^(3)和(3.50~6.14)×10^(12)m^(3),其中深层页岩气资源占比超过50%,主要分布在川东高陡构造带和川南低陡构造带;二叠系吴家坪组页岩气地质资源量和可采资源量分别为(8.7~24.6)×10^(12)m^(3)和(1.3~3.7)×10^(12)m^(3),在川东开江—梁平、龙驹坝、建南及三星等地区具有勘探潜力;寒武系筇竹寺组页岩气地质资源量和可采资源量分别为(5.69~12.71)×10^(12)m^(3)和(0.89~1.06)×10^(12)m^(3),其有利区主要分布在川西南井研—犍为—威远—资阳、川北南江及中扬子宜昌等地区;震旦系陡山沱组、蓟县系洪水庄组和青白口系下马岭组等海相古老层系具有一定的页岩气资源潜力,是潜在的页岩气资源接续,陡山沱组页岩气有利区主要分布在湘鄂西和渝东南地区,洪水庄组页岩气有利区主要分布在河北承德—宽城一带,下马岭组页岩气有利区主要分布在河北涿州—北京房山—门头沟—昌平一带和兰旗营子一带。基于此,进一步对海相页岩气未来勘探方向提出3点建议:一是聚焦深层—超深层、常压页岩气,走向新区新层系,拓宽页岩气勘探领域;二是深化深层—超深层、完善常压及丰富新区新层系页岩气勘探理论;三是着眼深层—超深层页岩气钻完井和开采技术与配套装备改进与创新,降低常压页岩气单井钻采成本。

四川盆地大安区块五峰组—龙马溪组深层页岩地质特征与勘探有利区

近年来,四川盆地渝西地区大安区块上奥陶统五峰组—下志留统龙一1亚段连续获得多口高产工业气井,展示了该区块页岩气良好的勘探开发前景。但由于该区块页岩埋藏深,勘探程度低,深层优质页岩段沉积微相类型、储层特征及其空间展布规律不清,页岩气有利区优选依据不充分,制约了该区页岩气的深化勘探与开发。为此,通过岩心观察、扫描电镜、地球化学与物性测试、含气量测定和核磁共振等实验手段分析,结合钻测井资料,研究了大安区块五峰组—龙一1亚段各小层地质特征及储层展布规律,建立了深层页岩气有利区评价标准,优选了深层页岩气勘探有利区。研究结果表明:①高碳硅质页岩微相和高碳含黏土硅质页岩微相是最优质页岩气储层发育的沉积微相,主要发育于五峰组—龙一13小层。②龙一11—龙一14小层孔隙度平均超过4%,储集性好;五峰组—龙一13小层超大孔和裂缝较发育,所占比例分别为66%和25%。③五峰组—龙一13小层脆性矿物平均含量为55%,可压性好;含气量平均值不低于4.0 m^(3)/t,含气条件较好;龙一11—龙一13小层各层平均总有机碳含量超过3.0%,生烃条件好;地层压力系数普遍大于1.90。结论认为:①五峰组—龙一13小层页岩储层品质最优;②Ⅰ类、Ⅱ类和Ⅲ类页岩气有利区资源量分别为3775.78×10^(8) m^(3)、2970.05×10^(8) m^(3)、599.83×10^(8) m^(3);③该区深层页岩气勘探潜力大,是四川盆地重要的天然气产能接替区,其中临江向斜为下一步页岩气勘探的最有利区。

Shale gas potential of the lower Silurian hot shales in southern Iran and the Arabian Plate: Characterization of organic geochemistry

A significant phase of global warming appeared during the Llandovery and productive Silurian hot shale was preserved all over the world.The lower Silurian shale is the main effective source rock for most of the Paleozoic hydrocarbon in Iran and the Arabian platform.Silurian hot shales have become prospective resources for new energy such as shale gas.The regional distribution and shale gas potential of the lower Silurian hot shale in southern Iran and the Arabian plate are determined using outcrops and exploration well samples data from previous studies.The studied area has a high organic content(on average more than 2%),maximum burial depth is 5300 m,shale thickness of 30-200 m,organic matter maturities(most comparable),clay minerals content ranging from 20%to 57%,quartz content ranges from 20%to 49%,feldspar content ranges from 10%to 15%and calcite content ranges from 1.48%to 5%which all favor shale gas generation and accumulation.We concluded that southern Iran and east-central Saudi Arabia are two of the most sustainable and favorable locations for shale gas exploration and production for lower Silurian hot shale after assessing all of the key characteristics.

Hydrocarbon accumulation and key exploration & development technologies of Changning-Weiyuan marine shale gas field, southern Sichuan

China is rich in shale gas resources and has broad prospects for development. However, the quality ofshale gas resources in China is different from that in the United States, so independent unique technologies are urgently required in China. In this regard, PetroChina has carried out theoretical andtechnical researches systematically on shale gas in Longmaxi Formation in southern Sichuan according toits geology-engineering characteristics. Guided by the “three-control” theory for marine shale gasenrichment and high yield (i.e. sedimentary diagenesis controls reservoir, preservation conditions control accumulation, and continuous thickness of Type I reservoir controls production), six key explorationand development technologies in southern China have been innovatively developed for marine shale gaswhich experienced multi-stage tectonic evolution. The technologies include comprehensive geologicalevaluation technology, development optimization technology, optimal and fast drilling technology forhorizontal well, volume fracturing technology for horizontal well, factory-like operation technology, andefficient clean production technology. These technologies have enabled the large-scale commercial recovery of shale gas. By the end of 2019, PetroChina had obtained proved geological reserves of1.06
1012 m3, had built production capacity of 10
109 m3, and had cumulative gas production of20
109 m3 in southern Sichuan. The remarkable results of application are of great significance forvigorously developing shale gas industry to reduce external dependence, ensure national energy security,and realize the strategy of "ecological priority and green development".

页岩气地质综合评价和目标优选

页岩气为烃源岩层系的油气聚集,属于源岩滞留气,以游离和吸附状态为主存在。中国页岩气资源调查和勘探开发刚刚起步,工作基础差别较大。在含油气盆地,由于有以往油气勘探开发资料,对含气页岩发育层系、有机质热演化程度、气显示等基本资料,具有一定的工作基础;在含油气盆地外以及油气勘探程度很低的沉积区,以上基础资料缺乏,仅有地表和部分固体矿产探井资料可供参照,工作基础薄弱。在不同工作基础的地区,页岩气地质综合评价所处阶段不同,主要评价指标也不同;随着工作程度的提高,资料的不断丰富,评价指标也逐步增加。页岩气地质评价以区域地质演化分析为基础,主要涉及以下几方面内容:(1)含气页岩评价。主要研究划定含气页岩层段,页岩的TOC、Ro、岩石和矿物成分,页岩分布、厚度、埋深、纵向和横向变化规律等,优选页岩气富集远景区。(2)页岩含气性和资源潜力评价。主要研究页岩的含气量、吸附能力、储集空间类型、储层物性、储层裂缝及其变化规律,预测页岩气资源潜力等。(3)页岩气开发条件和开发经济性评价。研究储层温度、流体压力、流体饱和度及流体性质,研究页岩的敏感性,页岩的岩石力学参数、区域现今应力场特征,地表条件和开发保障条件,通过试验井产量数据分析开发经济条件。综合各方面因素,优选有利开发区。

下扬子区上二叠统龙潭组页岩气勘探前景

通过对下扬子地区龙潭组页岩气基本地质条件的分析,并对比美国典型页岩气地质特征,认为下扬子地区上二叠统龙潭组具有良好的页岩气地质条件。通过构造、龙潭组暗色泥页岩的赋存特征和生烃条件的综合分析,将下扬子区龙潭组页岩气勘探分为3类区块,分别是Ⅰ类优选区块,Ⅱ类潜力区块和Ⅲ类前景区块,其中,Ⅰ类优选区块中皖南宣泾盆地水东向斜和环太湖锡澄虞地区的祝塘复向斜具有良好的页岩气生成和保存条件,是下扬子区页岩气的最有利勘探区。

四川盆地页岩气富集控制因素及类型

四川盆地页岩气具有多领域、多层系、多类型的特点。有利的沉积相、成熟度和保存条件是四川盆地页岩气富集的关键因素。海相深水陆棚优质页岩具有源、储、可压一体页岩气的富集条件，为最有利的沉积相类型。湖相碳酸盐湖坡风暴滩沉积的页岩与灰岩互层组合，具有源、储、可压近配页岩气富集条件，有利于微裂缝的发育，具有较好储渗性。适中的成熟度（2％～3％）生气高峰阶段，饱和气有机孔隙最发育，页岩的储集性最好。在埋藏条件下，页岩气的赋存总体上随着埋深增加，吸附气缓慢下降，而游离气则较快增加，超压区有利于游离气保存。在此研究基础上，将四川盆地页岩气划分为3个层系5种类型。其中，下志留统盆内缘超压和盆内超高压深水陆棚厚层页岩气型最有利于页岩气富集。依据各层系有利的沉积相带，适中演化程度（镜质体反射率1．3％～3．5％），压力系数大于1．2，埋深小于4500m分布区，预测出不同层系的页岩气有利区。

页岩气资源评价方法体系及其应用——以川西坳陷为例

根据页岩气发育条件及富集机理,结合油气资源评价方法的基本原则,系统归纳并建立了适合于不同地质及资料条件下的页岩气资源量与储量评价方法体系,包括:类比法(规模类比法、聚集条件类比法、综合类比法等)、成因法(产气历史分析法、剩余资源分析法、成因分析法等)、统计法(体积统计法、吸附要素分析法、地质要素分布概率风险分析法、产量分割法等)和综合分析法(蒙特卡洛法、打分法、盆地模拟法、专家赋值法、特尔菲综合法等)。通过对四川盆地川西坳陷页岩气地质条件和富集有利性的分析,优选上三叠统须家河组须五段为该地区页岩气发育且具有经济可采意义的有利层段。结合该地区实际地质条件,分别采用地质类比法、成因分析法和体积法对川西坳陷页岩气资源量进行了计算,运用特尔菲法加权得到该地区页岩气资源总量为1.47×1012～1.68×1012m3,均值为1.58×1012m3。平面上,页岩气勘探研究有利区主要分布于新场—德阳—广汉—新都—温江—大邑一线的成都凹陷。

上扬子地区下寒武统牛蹄塘组页岩气成藏条件

基于上扬子地区下寒武统牛蹄塘组黑色页岩的野外露头、钻井、岩心等资料，通过显微薄片、扫描电镜及X-衍射、压汞分析、等温吸附等多项实验测试分析，以牛蹄塘组黑色页岩的地层、岩石学、地球化学、地球物理和页岩含气性等为重点，对上扬子地区下寒武统牛蹄塘组页岩气形成的成藏条件与特征进行了初步探索。研究表明上扬子地区下寒武统牛蹄塘组以浅水-深水陆棚沉积环境控制富有机质页岩的发育，沉积厚度一般在50～300 m；有机碳含量在1.5％以上，有机质成熟度达到高-过成熟阶段；富有机质页岩脆性矿物丰富、粘土矿物演化程度高，以伊利石稳定矿物为主，不含蒙脱石；多种孔隙类型及裂缝发育，可为页岩气的赋存提供良好储集空间；富有机质页岩含气量达到了页岩气商业开发下限2.0 m3/t。综合各种成藏条件，认为资阳-自贡一带、黔北和渝东南-湘鄂西地区为页岩气有利勘探区带。

桂中坳陷下石炭统黑色页岩发育特征及页岩气勘探潜力

位于广西壮族自治区中部的桂中坳陷石炭系具有较好的页岩气勘探前景,但优质页岩的分布、品质和勘探潜力不清制约了该区页岩气的勘探成效。为了指导该坳陷石炭系页岩气的勘探,以下石炭统鹿寨组页岩为研究对象,利用该坳陷及周缘野外露头、钻井录井、分析测试等资料,对页岩地层的分布特征、有机地球化学特征、储集特征、保存条件等进行了系统研究,落实黑色页岩发育特征,总结优质页岩展布规律,分析页岩气勘探潜力,圈定勘探有利区带。研究结果表明:(1)桂中坳陷鹿寨组页岩以深水陆棚相沉积的碳质页岩、硅质页岩为主;(2)鹿寨组优质页岩厚度介于20～60 m,有机碳含量高、有机质类型好、有机质成熟度适中、脆性矿物含量高、储集物性较好、有机质孔隙发育;(3)柳城斜坡和宜山凹陷发育良好的区域盖层和顶底板,构造变形程度较弱,抬升剥蚀作用较弱,远离走滑性质较强的逆断层,具有良好的保存条件;(4)该坳陷早期地表构造所钻浅井气显示丰富、多口井获得天然气流,揭示了较好的页岩气勘探前景。结论认为,柳城斜坡带、宜山凹陷埋藏深度较大的宽缓向斜是该坳陷页岩气勘探的有利区。

准噶尔盆地南缘页岩气形成条件与有利区预测

通过对准噶尔盆地南缘泥页岩分布情况、厚度、面积、总有机碳含量、热演化程度、有机质类型、矿物岩石成分等因素的分析,确定了准噶尔盆地南缘侏罗系八道湾组、三工河组和西山窑组、二叠系芦草沟组、红雁池组以及石炭系是页岩气发育的有利层位。经过对有利层位的页岩气富集条件分析,并利用镜质体反射率(Ro)等值线、泥岩厚度等值线和总有机碳含量(TOC)等值线进行叠加的分析方法,最终确定霍玛吐背斜带西北缘、沙湾凹陷和莫南凸起三者过渡区域的侏罗纪地层,阜康凹陷与阜康断裂带过渡区域的侏罗纪地层,柴窝堡坳陷达坂城凹陷和永丰凹陷二叠纪地层埋藏较浅处,以及齐古断褶带石炭纪地层埋藏较浅处等4处为页岩的有利发育区。

库车拗陷页岩气聚集条件与勘探前景

分析库车拗陷钻井和地球化学资料,研究页岩气聚集的条件.结果表明：库车拗陷侏罗系—三叠系泥页岩有机碳质量分数高,集中分布在2.0%-3.0%之间;泥页岩厚度大,多数在200 m以上;干酪根类型以倾于生气的腐殖型为主;有机质成熟度分布较广,从0.6%-3.0%均有分布,主要集中分布在2.0%附近,有机质处于成熟—高熟阶段,具备形成页岩气的物质基础.库车拗陷构造活动强烈,逆掩断裂发育,为该地区泥页岩中天然裂缝的发育提供条件,有利于页岩气的富集和实现工业开采.利用多因素叠合法对库车拗陷页岩气有利聚集区进行预测,认为侏罗系页岩气聚集的有利区为拜城拗陷及克依构造带上,三叠系页岩气聚集的有利区集中分布在拜城拗陷,而在克依构造带有部分分布.