With the advancement of technology and the improvement of the level of understanding, deep hydrocarbon exploration in the Songliao basin has become one of the key objects. Wangfu fault depression is a typical oil-gas fault depression with a high degree of deep hydrocarbon exploration in the southeast of the Songliao basin. Finding out the oil-gas accumulation period of the deep hydrocarbon exploration is of great practical significance. The aim of the study is to find out the period and time of deep hydrocarbon accumulation in Wangfu fault depression, so as to provide an important theoretical basis for deep hydrocarbon exploration. The objective is to reveal the process and track of deep hydrocarbon accumulation of Huoshiling -Yingcheng Formations based on the lithofacies characteristics and the homogenization temperature distribution characteristics of fluid inclusions, combined with the burial history and thermal history simulation of strata in Wangfu fault depression. The results show that the reservoir of Huoshiling-Yingcheng Formations in Wangfu fault depression have experienced at least two periods of oil and gas filling events and two periods of oil filling events. The first hydrocarbon filling event was formed in the middle of Quantou period (about 95.4-97.5 Ma). Being influenced by the hydrocarbon expulsion from the source rocks of Huoshiling Formation, a large-scale oil and gas migration was formed. The second filling event occurred in the early Qingshankou period (about 93.6-92.0 Ma). During this period, the lake of the Songliao Basin expanded extensively, and the oil migrated and recharged through the opening fault on a large scale. The third filling event occurred in the late Qingshankou period (about 88.9-90.8 Ma), during which the source rocks of Shahezi Formation were in the peak of hydrocarbon generation and a large number of hydrocarbon migration occurred. The last large-scale filling event occurred in the early Nenjiang period (about 85.8-84.0 Ma). Affected by the rapid expansion of the lake basin in this period, the fault fractures reopened, resulting in the secondary migration and filling of oil.

The discoveries of oil and gas reservoirs in the volcanic rocks of the Songliao Basin (SB) have attracted the attention of many researchers. However, the lack of studies on the genesis of the volcanic rocks has led to different opinions being presented for the genesis of the SB. In order to solve this problem, this study selected the volcanic rocks of the Yingcheng Formation in the Southern Songliao Basin (SSB) as the research object, and determined the genesis and tectonic setting of the volcanic rocks by using LA‐ICP‐MS zircon U‐Pb dating and a geochemical analysis method (major elements, trace elements, and Hf isotopes). The volcanic rocks of the Yingcheng Formation are mainly composed of rhyolites with minor dacites and pyroclastic rocks. Our new zircon U‐Pb dating results show that these volcanic rocks were erupted in the Early Cretaceous (113–118 Ma). The primary zircons from the rhyolites have ∊Hf (t) values of +4.70 to +12.46 and two‐stage model age (TDM2) of 876–374 Ma. The geochemical data presented in this study allow these rhyolites to be divided into I‐type rhyolites and A‐type rhyolites, both of which were formed by the partial melting of the crust. They have SiO2 contents of 71.62 wt.%–75.76 wt.% and Al2O3 contentsof 10.88 wt.% to 12.92 wt.%. The rhyolites have distinctively higher REE contents than those of ordinary granites, with obvious negative Eu anomalies. The light to heavy REE fractionation is not obvious, and the LaN/YbN (average value = 9.78) is less than 10. The A‐type rhyolites depleted in Ba, Sr, P, and Ti, with relatively low Nb/Ta, indicating that the rocks belong A2 subtype granites formed in an extensional environment. The adakitic dacites are characterized by high Sr contents (624 to 1,082 ppm), low Y contents (10.6 to 12.6 ppm), high Sr/Y and Sr/Yb ratios, and low Mg# values (14.77 to 36.46), indicating that they belong to “C” type adakites. The adakitic dacite with high Sr and low Yb were likely generated by partial melting of the lower crust under high pressure conditions at least 40 km depth. The I‐type rhyolites with low Sr and high Yb, and the A‐type rhyolites with very low Sr and high Yb, were formed in the middle and upper crust under low pressure conditions, respectively. In addition, the formation depths of the former were approximately 30 km, whereas those of the latter were less than 30 km. The geochemical characteristics reveal that the volcanic rocks of Yingcheng Formation were formed in an extensional environment which was related to the retreat of subducted Paleo‐Pacific Plate. At the late Early Cretaceous Period, the upwelling of the asthenosphere mantle and the lithosphere delamination caused by the retreat of the subducted Paleo‐Pacific Plate, had resulted in lithosheric extension in the eastern part of China. Subsequently, a large area of volcanic rocks had formed. The SB has also been confirmed to be a product of the tectonic stress field in that region.

德惠断陷火山岩储层发育在火山机构以及部分风化壳中,笔者以其火山机构内幕型储层为研究对象,提出综合利用钻井、测井和地震资料对火山机构内幕进行火山机构-喷发单元-岩相逐级精细刻画的方法.通过对岩芯和薄片观察总结了8种火山岩储集空间类型,结合储层物性特征分析火山机构、喷发单元及岩相对火山岩储层的控制作用.研究结果表明:火山岩储层在火山机构中心和近火山口较为发育;喷发单元上部储层优于下部储层,喷发单元中部裂隙较为发育,可形成一套完整的孔隙-裂缝配置;火山岩相中以爆发相热碎屑流亚相、喷溢相上部亚相以及侵出相内带亚相为优质储层.

在盆地地质背景基础上,根据火山机构的宏观和微观特征,综合运用地质-地球物理等手段,在松辽盆地南部地区建立营城组火山机构地质模式,讨论不同类型火山机构的储层特征.火山机构识别综合利用3类方法:包含地质界面特征、岩性岩相特征、化学成分、喷发方式和单元叠置关系的地质识别,包含自然伽马测井、电阻率测井的测井识别以及包含地震相特征、地震反射特征、地震属性的地震识别.依据以上方法将德惠断陷营城组火山机构分成3类6种,包括流纹质熔岩机构、英安质熔岩机构、安山质熔岩机构、流纹质碎屑岩机构,安山质碎屑岩机构和复合火山机构.针对长岭断陷流纹质不同类型火山机构储层的孔隙度及储集空间类型进行统计,结果表明:复合火山机构的储层物性较好,碎屑岩火山机构的储层物性次之,熔岩火山机构的储层物性较差;酸性火山熔岩机构顶部物性最好,中部物性次之,底部物性最差;火山碎屑熔岩机构在横向上分布较为广泛,在纵向上由多个堆积单元组成.

In this study, we use seismic reflection, well-log and core data to investigate the basin structure and sedimentary filling of the Upper Jurassic and Lower Cretaceous in the Dehui Depression, Songliao Basin, Northeastern China. The Late Jurassic-Early Cretaceous Dehui Depression is an active-fault bounded graben. Unconformity and vertical variations on fault activity reveal that the syn-rift stage of the basin can be subdivided into four sub-stages: (i) early syn-rift stage (Huoshiling Formation), which is composed mainly of fan-delta and shallow lacustrine depositional systems; (ii) rift-climax stage (Shahezi Formation), which consists of sublacustrine fan, fan-delta and deep lacustrine depositional systems; (iii) late syn-rift stage (Yingcheng Formation), which is composed of fan-delta and shallow lacustrine depositional systems; (iv) rift-depression transition stage (Denglouku Formation), which is composed of braid delta and shallow lacustrine depositional systems. Fault evolution and episodic rifting control the basin geomorphology, and thus influenced the depositional systems of each stage, while the climate influenced the sediment type. Besides, our estimation on the hydrocarbon exploration potential of the rift-related successions in Dehui Depression shows that they can sustain the formation of medium-large gasfield.

Based on integrated analyze of core, well-logging, seismic and laboratory test data, sedimentary features and distribution pattern of the lakeshore bar are studied systematically. The lakeshore bar is mainly made up of fine sandstone and siltstone with such shallow water sedimentary structures as wave cross bedding, parallel and linsen bedding. Its facies sequences include the inverted and the composite. The cumulative grain-size distribution curves predominantly are two-stage. Oblique bars and orthogonal bars are formed at the bar fringe for lake current and wave kept acting on the lakeshore bars. The lakeshore bars were developed in lake-bays between deltas in descending half cycle of medium short-term strata cycles in the first and the second member of the Qingshankou Formation. Its distribution is obviously controlled by slope breaks and lake shoreline migration. The bar in the western actic region is characterized by thick sand and narrow facies belts. However, the bar in the southern gentle region is distinguished by thin sand and its multi-row distribution. As one of the favorite field of subtle reservoir exploration, the lakeshore bar is easily developed into multi-type of native reservoirs.

Shallow-water delta in large lacustrine depression basins is different from conventional delta in aspects of framework,microfacies,sandbody,scale and shape.In this article,forming conditions and deposition characteristics of K2y1 shallow-water deltas in the southern Songliao basin has been analyzed.Songliao basin are characterized by stable structure,slow subsidence,flat palaeotopography,dry climate and sufficient material source during Putaohua Formation,thus formed a distinctive shallow-water delta deposition.Unlike conventional terrigenous basins,its shoreline often migrated in large scale and few deep lacustrine and semi-deep lacustrine facies developed. The shallow-water delta can be distinguished by following characteristics:(1)The channel of shallow-water delta extended far away,up to 160 km from delta plain to lake center;Divaricating and confluence were often happen in delta.Sand bodies show obvious direction and birds foot-like distribution on the isopach map.(2)Mouth bar in the front of delta was not developed as restricted by accommodation and washing action.The sandstone reservoirs were obviously controlled by fluvial system.(3)Channel on the delta front were reformed to sheetlike sandstone by lake water and can be divided into three styles which include poorly sheetlike,moderately sheetlike and intensely sheetlike styles;(4)The sedimentary models of shallow-water delta differ from Gilbert delta style which have topset bed,bottomset bed and foreset bed.During K2y1 deposition period,the base level increased gradually,I and II sand group provided a favorable reservoir storage space,III sand group transgress provided a good seal for Putaohua reservoir.

Deep volcanic gas reservoirs have become an important growth point of oil and gas reserves in the south of Songliao Basin.The study on distribution and forming pattern of volcanic gas reservoirs is not thorough enough due to low degree of exploration.Based on in-depth analysis of the horizontal and vertical distribution characteristics of the reservoirs already discovered,three reservoir forming patterns are summarized for the east,central and west fault depressed zones.Based on deep geological understanding,the distribution and forming patterns of volcanic gas reservoirs are generalized to provide a thought for volcanic gas reservoir exploration.

The southern Songliao Basin have abundant natural gas source.But the genetic type of hydrocarbon gas are organic,abiogenetic and mixed.The organic type includes coal-formed gas and oil-formed gas.It perform as part-inversion and complete-inversion.To definite the source and origin of natural gas in Yingtai fault depression,according to geochemistry index,natural gas component,carbon isotopic and light hydrocarbon fingerprints of hydrocarbon source rocks,the genetic type of natural gas in the area of interest is analyed and the contrast of the source of natural gas is made.It can be concluded that the hydrocarbon gas in Yingtai fault depression contains the composition of condensate-associated gas and coal-formed gas.The natural gas in the southern sag mainly origins from Sahezi Group,and the northern are from Yingcheng Group.It affiliates to enhance the cognition of the hydrocarbon accumulation condition and accumulation model,in order to direct the research for the accumulation and distribution principle of natural gas and the further natural gas exploration.

By careful observation oil volcanic drilling cores, casting thin sections and statistical analysis of petrophysical properties, it can be suggested that the igneous rock reservoir of the Yingcheng Formation in the Changling fault depression is composed of different rock types, mainly rhyolite, ryholitic crystal tuff and in-situ autoclastic brecciation lava. There are different reservoir spaces in various lithological igneous rocks, but they are mainly composed of primary stomata, secondary solution pores and fractures. Their evolution processes can be divided into three stages: The primary reservoir space, exogenic leaching process and burial diagenesis. During the process, the reservoir qualities are affected by lithology and lithofacies, tectonics and dissolutions due to weathering leaching. Therefore, the near-crater facies of volcanic apparatus, which are distributed along the deep faults and dissolution zones on the high position of paleo-structures, are the favorable places for the high-quality volcanic reservoirs in the Changling fault depression.

This paper is to summarize and analyze key factors of volcanic gas accumulation.The results showed that although the six elements of accumulation(source rock,reservoir,cap rock,migration, trap and preservation)in the gas reservoir are indispensable,in terms of the deep formation in Songliao Basin,source rock conditions(mainly the development and distribution of deep gas source rocks)and reservoir conditions(development and distribution of excellent volcanic reservoirs)are even more important for the enrichment and accumulation of natural gas.In southeast rift zone where the tectonic movement is more intensive,fracture restricting the primary gas reservoir damage and secondary gas reservoir formation.Fault system and its evolution are,in the final analysis,the most fundamental and critical factor to various elements of accumulation,more or less,directly or indirectly.Can be said that not only the fault system controlling depression,but also control other elements of accumulation such as source rocks and generation of HCs,reservoir,migration,accumulation and preservation,thus affecting the volcanic gas reservoirs in the region the most fundamental and key constraints.

In order to evaluate and recognize the exploration potential of fault depressions except for the middle part fault depression where had a great breakthrough, the geological and geochemical data from the risk exploration well-Longshen 1, qualitative appraisement and quantitative calculation method are used to study gas source conditions and the exploration potential of Yingtai fault depression. This research indicates that dark mudstones of K1yc and K1sh layers are relatively development and the residual organic carbon content is relatively higher, and the organic matter is mainly at high-to over-mature evolution stage, especially with type Ⅱ1 and Ⅱ2 organic matter which have a higher gas generation potential, other than the type III organic matter accepted by predecessor. All above evidence hints there is a better exploration potential in deep fault depression. Meanwhile, the original carbon content and hydrocarbon potential of organic matter are much higher than present values, which indicate the signification of restitution for the objective appraisement of high-over-mature source rock. Quantitative appraisement preliminarily reveals that the gas resource of Yingtai fault depression is ranger from 93.8 to 375.8 billion cubic meters, where has a gas source condition for forming medium to large-sized gas fields or groups. It also means that some fault depressions have important and exploratory exploration potential, besides Xujiaweizi and Changling fault depression.

Based on substantial experimental material of reservoir,porosity and permeability parameters of the volcanic reservoir and the quantitative evaluation parameters of heterogeneity of Well Longshen 1 field of Yingtai fault is analyzed.The results show that volcanic reservoir physical properties change a lot in space.It has a strong non-homogeneous.This makes an effective reservoir prediction of volcanic difficulty.Using the imaging logging,indoor rock identification and casting thin section analysis,this study explores the mechanism and process that the various factors on the formation and transformation of the volcanic reservoir space,points out that lithology of the volcanic rocks is the base of other parameters having an impact on the reservoir properties.Volcanic subfacies are the main control factors of physical,diagenetic and tectonic aspects are an important factor on the physical properties,this makes an effective volcanic reservoir prediction have regulations to abide by.

The Longshen 1 well marks the breakthrough for deep gas exploration in the Yingtai depression in southern Songliao basin,and the ascription of its deep horizon is a key to the resource evaluation and reserve prediction in the Yingtai depression.The deep horizons in the Longshen 1 well were further subdivided by using rock-electric characteristics,correlation between wells,sporopollen assemblages and log and seismic data.The generalization is as the followings: the Yingcheng Group of the Longshen 1 well consisting of two set of thick volcanic(igneous rock) and two set of thin sedimentary rocks.They are significantly different from both the underlying and overlying layers in lithology,electrical property and seismic features.Its sporopollen characteristics were also distinct to those of the upper and lower formations,with gymnospermae pollen being up 65% and pteridophyta spore 35%,comparable to those of the Yingcheng Group in the northern Songliao basin.The top and bottom boundary of the Yingcheng Formation in the Longshen 1 well were 2 895 m and 3 532 m respectively and the Shahezi Formation has not been cut throught.

The unique tectonic setting and rift evolution of Songliao basin resulted in the formation and enrichment of volcanic CO2 gas pools. Mesozoic-Cenozoic volcano-magmatic activities developed in Songliao rift basin, with characteristics of multi-phase eruption, wide distribution and good reservoir condition. Volcanic activities were generally central vent eruption, mainly developing medium-basic and acidic volcanic assemblages, rhyolite, tuff and other rock types, two types of explosive facie and effusive facie. Mesozoic volcanic rocks are widely distributed in the basin, including Upper Jurassic Huoshiling Formation, Lower Cretaceous Yingeheng Formation constituting favorable reservoir of deep level of the basin, while Cenozoic volcanic rocks more exposed outside the basin and less drilled in the basin. Highly-enriched CO2 in the basin is of mantle-derived inorganic origin caused by mantle-derived magma degassing during Qingshankou and Cenozoic volcanic activity period. The formation of volcanic CO2 gas pools are mainly controlled by the background of deep structure, deep-large faults and Mesozoic-Cenozoic volcanic rocks. Discovered volcanic CO2 gas pools are mostly distributed in volcanic rocks of Yingcheng Formation in ancient central uplift and its adjacent faulted depression, characterized with point-belt distribution and local enrichment. Based on the controlling factor analysis, five CO2 accumulation plays were predicted.

It is very significant to probe the complex charging history in Chaluhe depression of Yitong basin.1D numeric modelling of hydrocarbon generation and expulsion history of source rocks in 4 wells confirms that the major source rocks had entered their threshold of maturity at the Middle-Late Eocene and reached the peak generation stage at the Early-Middle Oligocene.For this study,145 fluid inclusion samples from 19 wells have been employed to systematically obtain information on fluorescent colors of hydrocarbon inclusions,homogenization temperatures of oil inclusions and their coeval aqueous inclusions.The results indicate three events of oil charging for the Paleocene reservoirs.By integrating with the burial historical curves,the oil charging events have been reconstructed at 38.1-27 Ma,19.5-10 Ma and 1-0 Ma respectively.When combining the known information on hydrocarbon charging history and structural evolution,two intermittent periods of hydrocarbon migration and accumulation have been revealed,which were at 27-19.6 Ma and 10-2 Ma,respectively,corresponding to two structural uplift stages.In other words,tectonic uplift events occurring at the Late Palaeogene and the Early Neogene stopped the hydrocarbon supplies or destroyed the migrated and accumulated hydrocarbon so that hydrocarbon inclusions can not be probed at the two stages.Therefore,the Late Eocene to Middle Oligocene,Early-Middle Miocene and the Quaternary are the three important reservoir-forming periods in Chaluhe fault depression.

The dual structure of the complex fault depression in Songliao Basin and its geologic historic construction determined the existence of two sets of petroleum systems and their differences.The deep fault-depression group developed during Late Jurrasic to early Cretaceous and the particularity of the constructions of its inside sedimentary rock and volcanic rock determined the particularity of the natural gas enrichment conditions.The large thick limnetic facies in Shahezi Formation provided abundant organics for the formation of coal gas.The large-scale volcanic activities during fault-depression period and the strong geothermal field resulted from the huge thick and stable sediment during depression period sped up the transformation of hydrocarbon source rock and resulted in the formation of large amount of abiogenetic gas.The volcanic eruption within several ten thousands sq.km during the age of Yingcheng Formation formed the favorable facies belt with the stacked explosive facies and effusive facies,and developed the medium-acidic volcanic reservoir with pores and fractures.The relative independent volcanic rock formed the special trap type under the huge thick seal formation.The early-formed structure provided the trapping conditions for the formation of the primary gas pool.The late structural movement destroyed the primary gas pool,and developed the secondary gas pool.Meanwhile,the deep large fault was connected with the deep inorganic gas sources,forming the special CO2 gas reservoir.

Chaluhe faulted depression of Yitong Basin,an inland graben,has experienced multiple phased tectonic activities from the Late Cretaceous to the present.By means of microthermometry combined with the analysis of burial history,thermal history,and integrating hydrocarbon generation and expulsion history of major source rocks with tectonic movements,the hydrocarbon filling process can be subsequently divided into three episodes.While the GOI technology proves that the earlier filling hydrocarbon has been destructed at the peak of the structural closures,and the later filling hydrocarbon at the deeper structural closures are still preserved.This shows a favorable prospective for the future exploration.

According to traditional hydrocarbon genesis theory,it is accepted that organic maturity is affected by temperature,time and pressure.After summarizing exploration practices,it reveals that thermal maturity of organic matter is mainly controlled by temperature.So long as the temperature is high enough,substantial hydrocarbon can be generated from source rock.Tectonic movements do not only produce great amount of heat,but also make hydrocarbon generation and expulsion abruptly.Compressive process promote the hydrocarbon generation and migration.In addition,tectonic movements can form a set of traps,which shorten the time from generation to accumulation.Therefore,in areas where tectonic compression are well developed,though shallow buried source rock,they also have the capacity for hydrocarbon expulsion,and can form economic oil reservoirs.Based on these findings,the traditional theory that shallow source rock can not expulse oil should be broke,and regions of marginal basin with intense structural deformation should be taken into the exploratory frontier.

The deep beds of Changling fault depression is characterized by rich natural gas which can reach from 1.14×1012 m3 to 1.71×1012 m3(the average value is 1.42×1012 m3) according to the results of petroleum system simulation.The hydrocarbon gases and CO2 are distributed in different areas: the east part of the depression is rich in hydrocarbon gases;the west part is rich in CO2;the middle part is rich in the both kinds of gases.The distribution of hydrocarbon gases are controlled by source rocks,while the CO2 is closely related to the volcanic rocks and major basement faults.The comprehensive evaluations show five favorable regions,among which one is belong to typeⅠ,three belong to type Ⅱ,one belong to type Ⅲ.The typeⅠand type Ⅱ are the favorable regions to explore for the next step.