The Albertine Graben in western Uganda is a Mesozoic-Cenozoic rift basin with petroleum exploration potential. A fundamental evaluation of petroleum potential of the graben is given based on field research, data proce...The Albertine Graben in western Uganda is a Mesozoic-Cenozoic rift basin with petroleum exploration potential. A fundamental evaluation of petroleum potential of the graben is given based on field research, data processing of gravity and magnetism, analysis of graben structure, geochemistry, reservoir and composition research. The basin has a double-layered framework and a large thickness of sediments. Gravity highs shown in a residual anomaly map might indicate central uplift zones. There exist at least two sets of mature or low-maturity source rocks corresponding to a certain source rock in the Cretaceous or Paleogene and Neogene strata. The graben has basement rock with potential reservoirs and Tertiary sandstone reservoirs and thus has petroleum exploration potential.展开更多
A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed aro...A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed around the Manjiaer Sag in the eastern Tarim Basin. Some explorations occurred and no oil or gas field was discovered around the Awati Sag in the western Tarim Basin. Information from wells and outcrops reveals that there are excellent oil and gas source rock conditions around the Awati Sag. Transformed reef-shoal reservoirs could be formed in the Ordovician carbonate rocks with paleo-geographic background and hydrothermal conditions. Therefore, it is necessary to make a systematical study and overall evaluation of the potential of the periphery of the Awati Sag in terms of source rock evolution, resource potential, high-grade reservoir formation and distribution, and main factors controlling hydrocarbon migration and accumulation.展开更多
As the most important gold producer in China,the Northwest Jiaodong Peninsula is famous for its large gold deposits.In recent years,the discovery of gold mineralization has reached a depth of 4000 m below the surface ...As the most important gold producer in China,the Northwest Jiaodong Peninsula is famous for its large gold deposits.In recent years,the discovery of gold mineralization has reached a depth of 4000 m below the surface in this region.It has attracted significant interest from explorers about the prospecting potential at greater depths.Besides,the current deep drilling shows that the prospecting effect in the west portion is better than the region to the east.Does it imply that there is a difference in prospecting potential between the east and the west?This paper seeks to address the issue through fission track thermochronology on apatite and zircon to reveal the temperature-time evolution relationship of rock mass and to inverts their thermal evolution history.In addition,this study analyzes the transformation of ore deposits after mineralization,quantitatively calculates the uplift-erosion rate of rock mass,and summarizes the preservation law of ore deposits.Based on the thermal history simulation of the apatite fission track,our results show that the Guocheng gold belt has experienced three stages of thermal evolution:108-74,74-27,and 27-0 Ma.The uplift and cooling processes of the threestage tectonic uplift events are the results of multi-stage Pacific plate accretion.The calculated total denudation depth of the gold deposit in the Guocheng gold belt from Cretaceous to the present is about 3.4-5.3 km.The metallogenic depth of the ore body in the gold belt is 5.6-8.0 km,which indicates that the ore body in the Guocheng gold belt has suffered a significant degree of denudation.It is speculated that the location with less denudation in the southwest has greater prospecting potential.Our results quantitatively identify the uplift and denudation of the deposit after mineralization,which provides a new theoretical reference for regional mineralization,deep prospecting and exploration.展开更多
Large-scale oil exploration has been done and large quantities of oil-gas fields have been found in the northern shelf basin of the South China Sea for more than 20 years. The tectonic oil-gas pools are the main type....Large-scale oil exploration has been done and large quantities of oil-gas fields have been found in the northern shelf basin of the South China Sea for more than 20 years. The tectonic oil-gas pools are the main type. With the exploration to be deepened, looking for atectonic oil-gas pools is listed in China's exploration strategy. There are advantages for the forming of atectonic oil-gas pools in the northern shelf basin of the South China Sea. Because the level of water has been frequently changing within all historical periods, lithozones are changed alternately in both vertical and lateral directions and formed lithologic deposition especially at low water level stages, such as the low-lying fans of basin-floor fans and slope fans. Due to frequent tectonic movement within all historical periods, many structural surfaces and structural unconformities were formed. At the same time, they also formed many kinds of structural unconformity oil-gas pools. According to our exploration and research, the promising areas of atectonic reservoirs within marine basins include: (1) the basin-floor fan of the deep water district, such as the central depression of the Southeast Qiong basin and Baiyun sag in the Zhujiangkou basin; (2) the frontal area of the large ancient delta, such as the Lingao structural belt in the Yingge Sea basin and Huizhou sag in the Zhujiangkou basin; (3) the unconformity pinchout belt or denudation belt in the slope area and the uplift area, for instance, the Yingdong slope belt in the Yingge Sea basin and Yacheng 13-1 structural belt in the southeast Qiong basin. All this proves that the prospects for atectonic oil-gas pools in the northern shelf basin of the South China Sea are very broad.展开更多
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 ...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.展开更多
The Tamtsag Basin is located in the extreme eastern portion of the Mongolia. The Basin and its counterpart in China (the Hailar Basin) are united a whole basin on the structural setting. In recent years, the Tamtsag B...The Tamtsag Basin is located in the extreme eastern portion of the Mongolia. The Basin and its counterpart in China (the Hailar Basin) are united a whole basin on the structural setting. In recent years, the Tamtsag Basin attracts more and more attention with the important exploration discovered in the 19th block by SOCO and in Hailar Basin of China. This paper discusses the exploration potential of Tamtsag Basin from the viewpoint of petroleum geology.展开更多
The Carboniferous shale in the Guizhong Depression of central Guangxi presents good exploration potential of shale gas,but its exploration effectiveness is restricted by the unclear distribution,quality and potential ...The Carboniferous shale in the Guizhong Depression of central Guangxi presents good exploration potential of shale gas,but its exploration effectiveness is restricted by the unclear distribution,quality and potential of high-quality shale.In this paper,the Lower Carboniferous Luzhai shale was taken as the research object in order to guide the exploration of Carboniferous shale gas in the Guizhong Depression.Based on the field outcrops,well drilling,well logging and test data of the Guizhong Depression and its surrounding areas,the shale formation was studied systematically based on the characteristics of distribution,organic geochemistry and reservoir,and the preservation conditions.Then,the development characteristics of black shale were confirmed and the distribution laws of high-quality shale were summarized.Finally,shale gas exploration was analyzed and the favorable exploration areas were defined.And the following research results were obtained.First,the Luzhai shale in the Guizhong Depression is mainly carbonaceous shale and siliceous shale of deepwater continental shelf facies.Second,the high-quality Luzhai shale is 20-60 m thick and it is characterized by high total organic carbon,good type of organic matters,moderate maturity of organic matter,high content of brittle minerals,good reservoir property and developed pores of organic matters.Third,regional caprocks and roofs&floors are well developed in the Liucheng Slope and the Yishan Sag.They are weakly deformed,suffer from less uplift and denudation,and are far away from the strong strikeeslip reverse fault,so they have good preservation conditions.Fourth,shallow wells which were drilled in the surface structures of the Guizhong Depression in the early stage present abundant gas shows,and most of them produce gas flow,which reveals a promising prospect of shale gas exploration in this area.In conclusion,the wide and gentle synclines with large burial depth in the Liucheng Slope and the Yishan Sag are the favorable areas for shale gas exploration in the Guizhong Depression.展开更多
It was previously deemed that volcanic rocks in the western Sichuan Basin were not developed,which restricted the exploration of volcanic gas reservoirs in this area.Recently,however,Sinopec's wildcat well,Well YS...It was previously deemed that volcanic rocks in the western Sichuan Basin were not developed,which restricted the exploration of volcanic gas reservoirs in this area.Recently,however,Sinopec's wildcat well,Well YS1 encounters Upper Permian volcanic rocks about 300 m thick in the western Sichuan Basin,the reservoir physical properties of which are good with strong gas shows.In order to evaluate the exploration prospect of volcanic gas reservoirs in western Sichuan Basin,we studied the Permian volcanic rocks in this area from the aspects of formation and development characteristics,reservoir characteristics,gas genesis and plays based on the new understandings on exploration wells,com-bined with the analysis on tectonic evolution and its controlling effect on volcanism.Then,the volcanic eruption mechanism,the distribution mode of volcanic edifice and the hydrocarbon accumulation pattern of volcanic gas reservoir were figured out.Finally,the exploration potential of natural gas was evaluated.The following research results were obtained:(1)the Permian volcanic rocks in western Sichuan Basin are well developed and its tectonic setting is consistent with that of Emeishan basalt,which is the product of the Emeishan mantle plume.(2)Under the control of vertical faults,a great number of volcanic edifices are developed and there are many eruption cycles.Volcanic rocks are superimposed vertically and connected laterally.(3)The volcanic rocks in western Sichuan Basin are different to some extent from those in southwestern Sichuan Basin in terms of lithology,lithofacies and reservoir characteristics.In the western Sichuan Basin,the tuff of explosive facies is dominant with some basalt of effusive facies,and the reservoir space of volcanic rocks is mainly acted by inter-breccia skeletal pores,dissolved pores and matrix micro-pores.In conclusion,multiple sets of effective source rocks are developed around the volcanic intervals in western Sichuan Basin,and together they constitute effective natural gas plays.Therefore,it has a better natural gas exploration prospect,and it is a new field worthy of attention.展开更多
The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin.The efficiency of these source rocks is the key to the breakthrough in natural ...The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin.The efficiency of these source rocks is the key to the breakthrough in natural gas exploration in the study area.This paper analyzes the hydrocarbon potential of each sag in this basin from the perspective of control of both source rocks and geothermal heat.Two types of source rocks occur in the Yacheng Fm,namely mudstone of transitional facies and mudstone of neritic facies.Both of them are dominated by a kerogen of type-III,followed by type-II.Their organic matter abundances are controlled by the amount of continental clastic input.The mudstone of transitional facies is commonly higher in organic matter abundance,while that of neritic facies is lower.The coal-measure source rocks of transitional facies were mainly formed in such environments as delta plains,coastal plains and barrier tidal flat-marshes.Due to the control of Cenozoic lithosphere extension and influence of neotectonism,the geothermal gradient,terrestrial heat flow value(HFV)and level of thermal evolution are generally high in deep water.The hot setting not only determines the predominance of gas generation in the deep-water sags,but can promote the shallow-buried source rocks in shallow water into oil window to generate oil.In addition to promoting the hydrocarbon generation of source rocks,the high geothermal and high heat flow value can also speed up the cracking of residual hydrocarbons,thus enhancing hydrocarbon generation efficiency and capacity.According to the theory of joint control of source quality and geothermal heat on hydrocarbon generation,we comprehensively evaluate and rank the exploration potentials of major sags in the Qiongdongnan Basin.These sags are divided into 3 types,of which type-I sags including Yanan,Lingshui,Baodao,Ledong and Huaguang are the highest in hydrocarbon exploration potential.展开更多
Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow(7.5×10^(4) m^(3)/d gas and 9.8 m^(3)/d oil)from the Middle Jurassic Lianggaoshan Formation,presenting a g...Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow(7.5×10^(4) m^(3)/d gas and 9.8 m^(3)/d oil)from the Middle Jurassic Lianggaoshan Formation,presenting a good test production effects,which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin.In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas,this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells,such as wells Taiye 1 and Fuye 10.Then,the main factors controlling the enrichment of lacustrine shale oil and gas are discussed,and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined.And the following research results are obtained.First,the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance,high porosity and high gas content,and it is the geological base of shale oil and gas enrichment.Second,the developed large wide and gentle syncline,good preservation condition and higher pressure coefficient(generally>1.2)are the key to the enrichment and high yield of shale oil and gas.Third,the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas.In conclusion,the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth,developed microfractures and moderate thermal evolution,and its shale gas resource extent and shale oil resource extent are 1922×10^(8)m^(3)and 2800×10^(4)t,respectively,indicating greater potential of shale oil and gas exploration,so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.展开更多
Since the Anyue Gasfield,located in the central Sichuan paleo-uplift of the Sichuan Basin,was discovered,great efforts have been made to work on natural gas exploration and discovery in the SinianeLower Paleozoic in t...Since the Anyue Gasfield,located in the central Sichuan paleo-uplift of the Sichuan Basin,was discovered,great efforts have been made to work on natural gas exploration and discovery in the SinianeLower Paleozoic in the north slope of present paleo-uplift which has similar depositional settings.It is verified by the breakthrough of natural gas exploration in the second Member of Upper Sinian Dengying Formation in the north slope of central Sichuan paleo-uplift by wildcat well PT1 and the new sign of natural gas exploration in the Canglangpu Formation of Lower Cambrian and the fourth Member of Dengying Formation by Well JT1 that there are also favorable conditions for the formation of large-scale gas province in the north slope.In order to determine the natural gas exploration potential of SinianeLower Paleozoic in the central Sichuan paleo-uplift and provide the guidance for the following exploration deployment,this paper analyzed the petroleum geological conditions of SinianeLower Paleozoic in the north slope.And the following research results were obtained.First,the marginal platform belts in the second and the fourth Member of Sinian Dengying Formation in the north slope are basically separated areally,and they are superior to the Gaoshiti-Moxi area in terms of marginal platform width and sedimentary thickness and are intrinsically advantageous in sedimentation.Second,compared with the Gaoshiti-Moxi area,the reservoirs of Sinian Dengying Formation in the north slope are better in reservoir conditions,and many sets of quality reservoirs are developed vertically in Siniane-Cambrian.Third,hydrocarbon accumulation elements of Sinian Dengying Formation are better allocated in the north slope.Lithological traps are developed with a larger cumulative area.Wells JT1 and PT1 verify that there is gas in the lithological trap of the fourth and the second Member of Dengying Formation and large-scale lithological gas reservoirs are developed in the slope setting.In conclusion,compared with the Gaoshiti-Moxi area,the Sinian-Lower Paleozoic in the north slope is superior in petroleum geological conditions and has the advantage of multi-layer stereoscopic exploration vertically,presenting a great natural gas exploration potential and promising exploration prospects,so it is a new important strategic zone of conventional natural gas exploration in the Sichuan Basin.展开更多
Western Guizhou is a favorable region for coalbed methane(CBM)exploration and development in Guizhou Province.Affected by complex geological conditions,the heterogeneity of middle-high rank coal reservoirs is strong,a...Western Guizhou is a favorable region for coalbed methane(CBM)exploration and development in Guizhou Province.Affected by complex geological conditions,the heterogeneity of middle-high rank coal reservoirs is strong,and the geological and engineering control effects on enrichment and high productivity of CBM are significantly different.This paper comparatively analyzes the characteristics of middle-and high-rank coal reservoirs in the western Guizhou region,revealing the productivity characteristics and gas/water production rules of typical middle-high rank CBM high-yield wells.Moreover,it establishes a geological-engineering control model for the enrichment and high productivity of CBM in middle-high-rank coal seams in the western Guizhou region and analyzes the exploration and development potential and direction of middle-high-rank CBM in the region.The results are as follows.First,the middle-rank coal in the western Guizhou region is represented by the Liupanshui coalfield,where cleats and fractures are well developed,the content of macropores and mesopores is relatively high,the permeability is good,and the adsorption capacity is relatively weak.The high-rank coal is represented by the Zhina coalfield,where micropores are well developed,the permeability is greatly affected by burial depth,and the adsorption capacity is strong.Second,the difference in the characteristics of middle-rank and high-rank coal reservoirs in the western Guizhou region is mainly reflected in the pore-permeability conditions and adsorption capacity.The porosity and permeability of middle-rank coal samples are both greater than those of high-rank coal samples,and the development of secondary microfractures is the main reason for the relatively high permeability of middle-rank coal,while the well-developed micropores in high-rank coal provide more space for CBM preservation.Third,the CBM highyield wells in middle-rank coal seams in the western Guizhou region have the characteristics of“relatively high water production and high gas production,”while those of high-rank coal seams have the characteristics of“low water production and high gas production”or“high water production and low gas production.”The gas content and permeability of the coal reservoirs are the common constraints on whether CBM in middle-high rank coal seams can be highly productive under complex geological conditions.Fourth,the enrichment and high productivity of CBM in middle-high rank coal seams under complex geological conditions is the result of the synergistic matching of depth structure hydrology and adaptive fracturing production techniques.The CBM enrichment model,reservoir reformability,and gas/water production characteristics under geological and engineering synergistic control are unique and complex.Fifth,the middle-high rank coal seams in the western Guizhou region exhibit the basic resource characteristics of high gas content and high CBM resource abundance.Carrying out a precise evaluation of the CBM dual sweet spot system and reservoir volume stimulation are important guarantees for the efficient exploration and development of CBM in the western Guizhou region.展开更多
This work extensively investigated global tight sandstone gas, and geologically and geochemically analyzed the tight sandstone gas in China＇s Ordos, Sichuan, and Tarim basins. We compared typical tight sandstone gas ...This work extensively investigated global tight sandstone gas, and geologically and geochemically analyzed the tight sandstone gas in China＇s Ordos, Sichuan, and Tarim basins. We compared typical tight sandstone gas in China with that in North America. We proposed six conditions for the formation of China＇s tight sandstone gas, and illustrated the geological characteristics of tight sandstone gas. In China, gas-bearing tight sandstones were mainly deposited in continental lake deltas and marine-terrigenous facies basin environments, associated with coal-measure strata, and were mostly buried deeper than 2000 in under a formation pressure of 20-30 MPa, with pressure coefficients varying from overpressure to negative pressure. In other countries, tight gas bearing sandstones were dominantly deposited in marine to marine-terrigenous facies environments, occurred in coal-measure strata, and were mostly buried shallower than 2000 m in low-pressure systems. We systematically analyzed tight sandstone gas in the Ordos, Sichuan, and Tarim basins in terms of chemical compositions, geochemical characteristics of carbon isotopes, origins, and sources. Tight sandstone gas in China usually has a hydrocarbon content of 〉95%, with CH4 content 〉90%, and a generally higher dry coefficient. In the three above-mentioned large tight sandstone gas regions,δ13C1 and δJ3C2 mainly ranges from -42%o to -28%o and from -28%o to -21%o, respectively. Type III coal-measure source rocks that closely coexist with tight reservoirs are developed extensively in these gas regions. The organic petrology of source rocks and the carbon isotope compositions of gas indicate that tight sandstone gas in China is dominantly coal-derived gas generated by coal-measure strata. Our analysis of carbon isotope series shows that local isotope reversals are mainly caused by the mixing of gases of different maturities and that were generated at different stages. With increasing maturity, the reversal tendency becomes more apparent. Moreover, natural gas with medium-low maturity （e.g., Xujiahe Formation natural gas in the Sichuan Basin） presents an apparent reversal at a low-maturity stage, a normal series at a medium -maturity stage, and a reversal tendency again at a high-maturity stage. Finally, we proposed four conditions for preferred tight sandstone gas ＂sweep spots,＂ and illustrated the recoverable reserves, proven reserves, production, and exploration prospects of tight sandstone gas. The geological and geochemical characteristics, origins, sources, and exploration potential of tight sandstone gas in China from our research will be instructive for the future evaluation, prediction, and exploration of tight sandstone gas in China and abroad.展开更多
The northern area of the South Yellow Sea, located in the offshore region of China, resulted from the continental-continental collision orogeny during the Mesozoic and can be divided into four stages in terms of tecto...The northern area of the South Yellow Sea, located in the offshore region of China, resulted from the continental-continental collision orogeny during the Mesozoic and can be divided into four stages in terms of tectonic evolution： （1） pre-orogenic passive continental margin stage （Z-T2）; （2） foreland basin stage corresponding with the late phase of the Sulu （苏鲁） orogeny （J3-K）; （3） post-orogenic intracontinental rifted basin stage （K2t-E）; and （4） regional subsidence and coverage stage （N-Q）. Based on detailed investigation and study of the intracontinental rifted basin, hydrocar- bon source rocks of Late Cretaceous Taizhou （泰州） Formation distributed well in the basin, and four reservoir-cap combinations as well as numerous trap structures were found. As a result, the geological conditions would be excellent for reservoir formation in the basin, and the oil resource amount is estimated at about 20×10^8 t, which makes the basin a major target for hydrocarbon exploration in the South Yellow Sea.展开更多
Recently,a high-yield gas flow of 22.5×10^(4)m^(3)/d was achieved in the wildcat well Yongtan 1,deployed by PetroChina Southwest Oil and Gasfield Company,and an extrusive facies volcaniclastic gas reservoir was f...Recently,a high-yield gas flow of 22.5×10^(4)m^(3)/d was achieved in the wildcat well Yongtan 1,deployed by PetroChina Southwest Oil and Gasfield Company,and an extrusive facies volcaniclastic gas reservoir was first discovered in the Sichuan Basin,which is a major breakthrough in the exploration of volcanic rock gas reservoirs.In order to further evaluate the exploration potential in Permian volcanic rock gas reservoirs in this basin,we systematically reviewed and summarized the exploration process of volcanic rocks in this study area,as well as the characteristics of gas reservoirs of well Yongtan 1,the controlling factors and modes of hydrocarbon accumulation.The following findings were obtained.(1)Over the past five decades of gas exploration of volcanic rocks,the change of exploration thought and progress in seismic prediction contribute to a major discovery in this study area,i.e.,the well location deployment of Yongtan 1 was determined in the Jianyan area,where the volcanic anomalies of the Permian developed outbursts are well developed and the gas reservoir conditions are favorable.This also proves that another new gas exploration area in this basin was found.(2)From the data of Yongtan 1,we found high-quality volcanic porous reservoirs with a thickness of over 100 m developed in the Permian strata,the effusive volcanic rock types dominated by breccia and tuffaceous breccia,reservoir space composed of dissolution pores,interbreccia dissolution pores,and other pores,the porosity of which is 6.68%-13.22%and 10.26%on average,the permeability 0.01-4.43 mD and 2.35 mD on average.(3)This abnormally high pressure gas reservoir was buried 4500-6000 m deep underground with the middle formation pressure being 125.625 MPa and the pressure coefficient being up to 2.22.Methane content in the minor H_(2)S-bearing produced gas flow reached up to 99.03%.(4)Volcanic rocks in the Jianyang-Zhongjiang-Santai area are developed,and they are adjacent to the Cambrian high-quality source rocks in the Deyang-Anyue rifting.The early extensional deep faults play a role in connecting source and storage.There are many sets of caprocks,such as the Upper Permian Longtan Formation and Lower Triassic layered thick paste rocks,providing conditions for forming large-scale tectonic-lithologic composite trap gas reservoirs,and the favorable exploration area reaches up to 6000 km^(2).In conclusion,this major discovery not only proves that Permian volcanic rocks in the Sichuan Basin has large potential for oil and gas exploration,but reaffirms the confidence in changing our exploration thought,speeding up new exploration zones and areas,and discovering more and bigger gas fields.展开更多
At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic res...At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic reservoirs) have been found. Since both the amount and reserve of the discovered subtle reservoirs are small, a great exploration potential remains in the Taibei Sag. The shallow to medium formations in the west of the Taibei Sag were divided into three second-order sequences and ten third-order sequences, of which the rising cyclothems of SQ(J2q) and SQ8 (J2s2) datum level are major exploration targets for the subtle reservoirs (lithologic). The depositional systems of Qiquanhu and Subashi braided river delta were developed there, where the sedimentary sand body is dominated by the regional slopes and slope break belts. There are four main modes the formation of lithologic traps: deltaic front onlap on the slope belt, deltaic front toplap on the slope break belt, lately tilted frontal sand body and sublacustrine fan—slope fan on the slope break belt, of which the first three modes are the major styles of the formation of subtle reservoirs. Major targets for subtle reservoir exploration in the near future include Putaogou Member on the north slope of Huoyanshan, the east slope of Pubei, the nose-like palaeohigh regions of Huobei, Subashi and Lianmuqin, around the Shengbei secondary sag.展开更多
The aim of this article is to explore potential directions for the development of artificial intelligence(AI).It points out that,while current AI can handle the statistical properties of complex systems,it has difficu...The aim of this article is to explore potential directions for the development of artificial intelligence(AI).It points out that,while current AI can handle the statistical properties of complex systems,it has difficulty effectively processing and fully representing their spatiotemporal complexity patterns.The article also discusses a potential path of AI development in the engineering domain.Based on the existing understanding of the principles of multilevel com-plexity,this article suggests that consistency among the logical structures of datasets,AI models,model-building software,and hardware will be an important AI development direction and is worthy of careful consideration.展开更多
文摘The Albertine Graben in western Uganda is a Mesozoic-Cenozoic rift basin with petroleum exploration potential. A fundamental evaluation of petroleum potential of the graben is given based on field research, data processing of gravity and magnetism, analysis of graben structure, geochemistry, reservoir and composition research. The basin has a double-layered framework and a large thickness of sediments. Gravity highs shown in a residual anomaly map might indicate central uplift zones. There exist at least two sets of mature or low-maturity source rocks corresponding to a certain source rock in the Cretaceous or Paleogene and Neogene strata. The graben has basement rock with potential reservoirs and Tertiary sandstone reservoirs and thus has petroleum exploration potential.
文摘A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed around the Manjiaer Sag in the eastern Tarim Basin. Some explorations occurred and no oil or gas field was discovered around the Awati Sag in the western Tarim Basin. Information from wells and outcrops reveals that there are excellent oil and gas source rock conditions around the Awati Sag. Transformed reef-shoal reservoirs could be formed in the Ordovician carbonate rocks with paleo-geographic background and hydrothermal conditions. Therefore, it is necessary to make a systematical study and overall evaluation of the potential of the periphery of the Awati Sag in terms of source rock evolution, resource potential, high-grade reservoir formation and distribution, and main factors controlling hydrocarbon migration and accumulation.
基金co-financed by the National Key Research and Development Plan(No.2016YFC0600104)the Geological Research Project of China+1 种基金the National Gold Group Co.,Ltd.Xintai Gold Mining Co.,Ltd(Yantai,Shandong)(No.XY-DZ2020081)。
文摘As the most important gold producer in China,the Northwest Jiaodong Peninsula is famous for its large gold deposits.In recent years,the discovery of gold mineralization has reached a depth of 4000 m below the surface in this region.It has attracted significant interest from explorers about the prospecting potential at greater depths.Besides,the current deep drilling shows that the prospecting effect in the west portion is better than the region to the east.Does it imply that there is a difference in prospecting potential between the east and the west?This paper seeks to address the issue through fission track thermochronology on apatite and zircon to reveal the temperature-time evolution relationship of rock mass and to inverts their thermal evolution history.In addition,this study analyzes the transformation of ore deposits after mineralization,quantitatively calculates the uplift-erosion rate of rock mass,and summarizes the preservation law of ore deposits.Based on the thermal history simulation of the apatite fission track,our results show that the Guocheng gold belt has experienced three stages of thermal evolution:108-74,74-27,and 27-0 Ma.The uplift and cooling processes of the threestage tectonic uplift events are the results of multi-stage Pacific plate accretion.The calculated total denudation depth of the gold deposit in the Guocheng gold belt from Cretaceous to the present is about 3.4-5.3 km.The metallogenic depth of the ore body in the gold belt is 5.6-8.0 km,which indicates that the ore body in the Guocheng gold belt has suffered a significant degree of denudation.It is speculated that the location with less denudation in the southwest has greater prospecting potential.Our results quantitatively identify the uplift and denudation of the deposit after mineralization,which provides a new theoretical reference for regional mineralization,deep prospecting and exploration.
文摘Large-scale oil exploration has been done and large quantities of oil-gas fields have been found in the northern shelf basin of the South China Sea for more than 20 years. The tectonic oil-gas pools are the main type. With the exploration to be deepened, looking for atectonic oil-gas pools is listed in China's exploration strategy. There are advantages for the forming of atectonic oil-gas pools in the northern shelf basin of the South China Sea. Because the level of water has been frequently changing within all historical periods, lithozones are changed alternately in both vertical and lateral directions and formed lithologic deposition especially at low water level stages, such as the low-lying fans of basin-floor fans and slope fans. Due to frequent tectonic movement within all historical periods, many structural surfaces and structural unconformities were formed. At the same time, they also formed many kinds of structural unconformity oil-gas pools. According to our exploration and research, the promising areas of atectonic reservoirs within marine basins include: (1) the basin-floor fan of the deep water district, such as the central depression of the Southeast Qiong basin and Baiyun sag in the Zhujiangkou basin; (2) the frontal area of the large ancient delta, such as the Lingao structural belt in the Yingge Sea basin and Huizhou sag in the Zhujiangkou basin; (3) the unconformity pinchout belt or denudation belt in the slope area and the uplift area, for instance, the Yingdong slope belt in the Yingge Sea basin and Yacheng 13-1 structural belt in the southeast Qiong basin. All this proves that the prospects for atectonic oil-gas pools in the northern shelf basin of the South China Sea are very broad.
基金supported by National Science and Technology Major Project entitled Test and Application Promotion of Shale Gas Exploration and Evaluation Techniques(No.2016ZX05034)a project organized by the China Geological Survey entitled Shale Gas Geological Survey in Northeastern Yunnan(No.DD20190080).
文摘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.
文摘The Tamtsag Basin is located in the extreme eastern portion of the Mongolia. The Basin and its counterpart in China (the Hailar Basin) are united a whole basin on the structural setting. In recent years, the Tamtsag Basin attracts more and more attention with the important exploration discovered in the 19th block by SOCO and in Hailar Basin of China. This paper discusses the exploration potential of Tamtsag Basin from the viewpoint of petroleum geology.
基金Project supported by the National Major Science and Technology Project“Shale Gas Play Evaluation and Exploration Technologies”(No.:2017ZX05036).
文摘The Carboniferous shale in the Guizhong Depression of central Guangxi presents good exploration potential of shale gas,but its exploration effectiveness is restricted by the unclear distribution,quality and potential of high-quality shale.In this paper,the Lower Carboniferous Luzhai shale was taken as the research object in order to guide the exploration of Carboniferous shale gas in the Guizhong Depression.Based on the field outcrops,well drilling,well logging and test data of the Guizhong Depression and its surrounding areas,the shale formation was studied systematically based on the characteristics of distribution,organic geochemistry and reservoir,and the preservation conditions.Then,the development characteristics of black shale were confirmed and the distribution laws of high-quality shale were summarized.Finally,shale gas exploration was analyzed and the favorable exploration areas were defined.And the following research results were obtained.First,the Luzhai shale in the Guizhong Depression is mainly carbonaceous shale and siliceous shale of deepwater continental shelf facies.Second,the high-quality Luzhai shale is 20-60 m thick and it is characterized by high total organic carbon,good type of organic matters,moderate maturity of organic matter,high content of brittle minerals,good reservoir property and developed pores of organic matters.Third,regional caprocks and roofs&floors are well developed in the Liucheng Slope and the Yishan Sag.They are weakly deformed,suffer from less uplift and denudation,and are far away from the strong strikeeslip reverse fault,so they have good preservation conditions.Fourth,shallow wells which were drilled in the surface structures of the Guizhong Depression in the early stage present abundant gas shows,and most of them produce gas flow,which reveals a promising prospect of shale gas exploration in this area.In conclusion,the wide and gentle synclines with large burial depth in the Liucheng Slope and the Yishan Sag are the favorable areas for shale gas exploration in the Guizhong Depression.
基金Project supported by Sinopec Science and Technology Special Project“Evaluation of Hydrocarbon Formation Conditions and Targets of Permian Volcanic Rocks in Western Sichuan”(No.P18069-3)National Science and Technology Major Special Project“Evaluation and Strategic zone selection of Hydrocarbon Resources Potential of Marine Carbonate Strata”(No.2017ZX05005001-004).
文摘It was previously deemed that volcanic rocks in the western Sichuan Basin were not developed,which restricted the exploration of volcanic gas reservoirs in this area.Recently,however,Sinopec's wildcat well,Well YS1 encounters Upper Permian volcanic rocks about 300 m thick in the western Sichuan Basin,the reservoir physical properties of which are good with strong gas shows.In order to evaluate the exploration prospect of volcanic gas reservoirs in western Sichuan Basin,we studied the Permian volcanic rocks in this area from the aspects of formation and development characteristics,reservoir characteristics,gas genesis and plays based on the new understandings on exploration wells,com-bined with the analysis on tectonic evolution and its controlling effect on volcanism.Then,the volcanic eruption mechanism,the distribution mode of volcanic edifice and the hydrocarbon accumulation pattern of volcanic gas reservoir were figured out.Finally,the exploration potential of natural gas was evaluated.The following research results were obtained:(1)the Permian volcanic rocks in western Sichuan Basin are well developed and its tectonic setting is consistent with that of Emeishan basalt,which is the product of the Emeishan mantle plume.(2)Under the control of vertical faults,a great number of volcanic edifices are developed and there are many eruption cycles.Volcanic rocks are superimposed vertically and connected laterally.(3)The volcanic rocks in western Sichuan Basin are different to some extent from those in southwestern Sichuan Basin in terms of lithology,lithofacies and reservoir characteristics.In the western Sichuan Basin,the tuff of explosive facies is dominant with some basalt of effusive facies,and the reservoir space of volcanic rocks is mainly acted by inter-breccia skeletal pores,dissolved pores and matrix micro-pores.In conclusion,multiple sets of effective source rocks are developed around the volcanic intervals in western Sichuan Basin,and together they constitute effective natural gas plays.Therefore,it has a better natural gas exploration prospect,and it is a new field worthy of attention.
基金National Key Basic Research and Development Plan(973 plans)“Basic research on oil and gas formation and distribution in deep water basins in South China Sea”(No.2009CB219400)Special and Significant Project of National Science and Technology“Key technology of marine oil and gas exploration in deep water area”(No.2008ZX05025 and 2011ZX05025)Investigation and Evaluation Project of National Strategic Petroleum Resource Provinces of the Ministry of Land and Resources(No.XQ-2004-05 and XQ-2007-05).
文摘The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin.The efficiency of these source rocks is the key to the breakthrough in natural gas exploration in the study area.This paper analyzes the hydrocarbon potential of each sag in this basin from the perspective of control of both source rocks and geothermal heat.Two types of source rocks occur in the Yacheng Fm,namely mudstone of transitional facies and mudstone of neritic facies.Both of them are dominated by a kerogen of type-III,followed by type-II.Their organic matter abundances are controlled by the amount of continental clastic input.The mudstone of transitional facies is commonly higher in organic matter abundance,while that of neritic facies is lower.The coal-measure source rocks of transitional facies were mainly formed in such environments as delta plains,coastal plains and barrier tidal flat-marshes.Due to the control of Cenozoic lithosphere extension and influence of neotectonism,the geothermal gradient,terrestrial heat flow value(HFV)and level of thermal evolution are generally high in deep water.The hot setting not only determines the predominance of gas generation in the deep-water sags,but can promote the shallow-buried source rocks in shallow water into oil window to generate oil.In addition to promoting the hydrocarbon generation of source rocks,the high geothermal and high heat flow value can also speed up the cracking of residual hydrocarbons,thus enhancing hydrocarbon generation efficiency and capacity.According to the theory of joint control of source quality and geothermal heat on hydrocarbon generation,we comprehensively evaluate and rank the exploration potentials of major sags in the Qiongdongnan Basin.These sags are divided into 3 types,of which type-I sags including Yanan,Lingshui,Baodao,Ledong and Huaguang are the highest in hydrocarbon exploration potential.
基金Project supported by the National Major Science and Technology Project“Target Assessment and Exploration Technologies of Shale Gas Play”(No.:2017ZX05036)the Sinopec“Ten Major”Scientific and Technological Projects“Exploration and Evaluation Techniques of Jurassic Continental Shale Oil and Gas”(No.:P21078-1).
文摘Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow(7.5×10^(4) m^(3)/d gas and 9.8 m^(3)/d oil)from the Middle Jurassic Lianggaoshan Formation,presenting a good test production effects,which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin.In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas,this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells,such as wells Taiye 1 and Fuye 10.Then,the main factors controlling the enrichment of lacustrine shale oil and gas are discussed,and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined.And the following research results are obtained.First,the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance,high porosity and high gas content,and it is the geological base of shale oil and gas enrichment.Second,the developed large wide and gentle syncline,good preservation condition and higher pressure coefficient(generally>1.2)are the key to the enrichment and high yield of shale oil and gas.Third,the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas.In conclusion,the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth,developed microfractures and moderate thermal evolution,and its shale gas resource extent and shale oil resource extent are 1922×10^(8)m^(3)and 2800×10^(4)t,respectively,indicating greater potential of shale oil and gas exploration,so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.
基金supported by the National Major Science and Technology Project“Development of large-scale oil/gas fields and coalbed methane”(No.2016ZX05004-005)PetroChina Company Limited's Major Science and Technology Project“Key technology for achieving 30 BCM gas production and its application in Southwest Oil/Gas Field”(No.2016E-0602).
文摘Since the Anyue Gasfield,located in the central Sichuan paleo-uplift of the Sichuan Basin,was discovered,great efforts have been made to work on natural gas exploration and discovery in the SinianeLower Paleozoic in the north slope of present paleo-uplift which has similar depositional settings.It is verified by the breakthrough of natural gas exploration in the second Member of Upper Sinian Dengying Formation in the north slope of central Sichuan paleo-uplift by wildcat well PT1 and the new sign of natural gas exploration in the Canglangpu Formation of Lower Cambrian and the fourth Member of Dengying Formation by Well JT1 that there are also favorable conditions for the formation of large-scale gas province in the north slope.In order to determine the natural gas exploration potential of SinianeLower Paleozoic in the central Sichuan paleo-uplift and provide the guidance for the following exploration deployment,this paper analyzed the petroleum geological conditions of SinianeLower Paleozoic in the north slope.And the following research results were obtained.First,the marginal platform belts in the second and the fourth Member of Sinian Dengying Formation in the north slope are basically separated areally,and they are superior to the Gaoshiti-Moxi area in terms of marginal platform width and sedimentary thickness and are intrinsically advantageous in sedimentation.Second,compared with the Gaoshiti-Moxi area,the reservoirs of Sinian Dengying Formation in the north slope are better in reservoir conditions,and many sets of quality reservoirs are developed vertically in Siniane-Cambrian.Third,hydrocarbon accumulation elements of Sinian Dengying Formation are better allocated in the north slope.Lithological traps are developed with a larger cumulative area.Wells JT1 and PT1 verify that there is gas in the lithological trap of the fourth and the second Member of Dengying Formation and large-scale lithological gas reservoirs are developed in the slope setting.In conclusion,compared with the Gaoshiti-Moxi area,the Sinian-Lower Paleozoic in the north slope is superior in petroleum geological conditions and has the advantage of multi-layer stereoscopic exploration vertically,presenting a great natural gas exploration potential and promising exploration prospects,so it is a new important strategic zone of conventional natural gas exploration in the Sichuan Basin.
基金supported by the“Belt and Road”Innovation Cooperation Project of Jiangsu Province(Grant No.BZ2022015)the National Natural Science Foundation of China(No.42030810 and 42102207)Geological Exploration Foundation of Guizhou Province(No.52000021MGQSE7S7K6PRP).
文摘Western Guizhou is a favorable region for coalbed methane(CBM)exploration and development in Guizhou Province.Affected by complex geological conditions,the heterogeneity of middle-high rank coal reservoirs is strong,and the geological and engineering control effects on enrichment and high productivity of CBM are significantly different.This paper comparatively analyzes the characteristics of middle-and high-rank coal reservoirs in the western Guizhou region,revealing the productivity characteristics and gas/water production rules of typical middle-high rank CBM high-yield wells.Moreover,it establishes a geological-engineering control model for the enrichment and high productivity of CBM in middle-high-rank coal seams in the western Guizhou region and analyzes the exploration and development potential and direction of middle-high-rank CBM in the region.The results are as follows.First,the middle-rank coal in the western Guizhou region is represented by the Liupanshui coalfield,where cleats and fractures are well developed,the content of macropores and mesopores is relatively high,the permeability is good,and the adsorption capacity is relatively weak.The high-rank coal is represented by the Zhina coalfield,where micropores are well developed,the permeability is greatly affected by burial depth,and the adsorption capacity is strong.Second,the difference in the characteristics of middle-rank and high-rank coal reservoirs in the western Guizhou region is mainly reflected in the pore-permeability conditions and adsorption capacity.The porosity and permeability of middle-rank coal samples are both greater than those of high-rank coal samples,and the development of secondary microfractures is the main reason for the relatively high permeability of middle-rank coal,while the well-developed micropores in high-rank coal provide more space for CBM preservation.Third,the CBM highyield wells in middle-rank coal seams in the western Guizhou region have the characteristics of“relatively high water production and high gas production,”while those of high-rank coal seams have the characteristics of“low water production and high gas production”or“high water production and low gas production.”The gas content and permeability of the coal reservoirs are the common constraints on whether CBM in middle-high rank coal seams can be highly productive under complex geological conditions.Fourth,the enrichment and high productivity of CBM in middle-high rank coal seams under complex geological conditions is the result of the synergistic matching of depth structure hydrology and adaptive fracturing production techniques.The CBM enrichment model,reservoir reformability,and gas/water production characteristics under geological and engineering synergistic control are unique and complex.Fifth,the middle-high rank coal seams in the western Guizhou region exhibit the basic resource characteristics of high gas content and high CBM resource abundance.Carrying out a precise evaluation of the CBM dual sweet spot system and reservoir volume stimulation are important guarantees for the efficient exploration and development of CBM in the western Guizhou region.
基金supported by the Petro China Major Scientific and Technical Project (No.: 2014B-0608)the National Science and Technology Major Project of China (NO.: 2011ZX5001-001)
文摘This work extensively investigated global tight sandstone gas, and geologically and geochemically analyzed the tight sandstone gas in China＇s Ordos, Sichuan, and Tarim basins. We compared typical tight sandstone gas in China with that in North America. We proposed six conditions for the formation of China＇s tight sandstone gas, and illustrated the geological characteristics of tight sandstone gas. In China, gas-bearing tight sandstones were mainly deposited in continental lake deltas and marine-terrigenous facies basin environments, associated with coal-measure strata, and were mostly buried deeper than 2000 in under a formation pressure of 20-30 MPa, with pressure coefficients varying from overpressure to negative pressure. In other countries, tight gas bearing sandstones were dominantly deposited in marine to marine-terrigenous facies environments, occurred in coal-measure strata, and were mostly buried shallower than 2000 m in low-pressure systems. We systematically analyzed tight sandstone gas in the Ordos, Sichuan, and Tarim basins in terms of chemical compositions, geochemical characteristics of carbon isotopes, origins, and sources. Tight sandstone gas in China usually has a hydrocarbon content of 〉95%, with CH4 content 〉90%, and a generally higher dry coefficient. In the three above-mentioned large tight sandstone gas regions,δ13C1 and δJ3C2 mainly ranges from -42%o to -28%o and from -28%o to -21%o, respectively. Type III coal-measure source rocks that closely coexist with tight reservoirs are developed extensively in these gas regions. The organic petrology of source rocks and the carbon isotope compositions of gas indicate that tight sandstone gas in China is dominantly coal-derived gas generated by coal-measure strata. Our analysis of carbon isotope series shows that local isotope reversals are mainly caused by the mixing of gases of different maturities and that were generated at different stages. With increasing maturity, the reversal tendency becomes more apparent. Moreover, natural gas with medium-low maturity （e.g., Xujiahe Formation natural gas in the Sichuan Basin） presents an apparent reversal at a low-maturity stage, a normal series at a medium -maturity stage, and a reversal tendency again at a high-maturity stage. Finally, we proposed four conditions for preferred tight sandstone gas ＂sweep spots,＂ and illustrated the recoverable reserves, proven reserves, production, and exploration prospects of tight sandstone gas. The geological and geochemical characteristics, origins, sources, and exploration potential of tight sandstone gas in China from our research will be instructive for the future evaluation, prediction, and exploration of tight sandstone gas in China and abroad.
基金supported by the National Natural Science Foundation of China (No. 40620140435)
文摘The northern area of the South Yellow Sea, located in the offshore region of China, resulted from the continental-continental collision orogeny during the Mesozoic and can be divided into four stages in terms of tectonic evolution： （1） pre-orogenic passive continental margin stage （Z-T2）; （2） foreland basin stage corresponding with the late phase of the Sulu （苏鲁） orogeny （J3-K）; （3） post-orogenic intracontinental rifted basin stage （K2t-E）; and （4） regional subsidence and coverage stage （N-Q）. Based on detailed investigation and study of the intracontinental rifted basin, hydrocar- bon source rocks of Late Cretaceous Taizhou （泰州） Formation distributed well in the basin, and four reservoir-cap combinations as well as numerous trap structures were found. As a result, the geological conditions would be excellent for reservoir formation in the basin, and the oil resource amount is estimated at about 20×10^8 t, which makes the basin a major target for hydrocarbon exploration in the South Yellow Sea.
基金supported by the Major Science&Technology Special Project of PetroChina Company Limited“Research and Application of Key Technologies for 300×10^(8) m^(3) Gas Productivity in Southwest Oil&Gasfield”(No.:2016E-0604).
文摘Recently,a high-yield gas flow of 22.5×10^(4)m^(3)/d was achieved in the wildcat well Yongtan 1,deployed by PetroChina Southwest Oil and Gasfield Company,and an extrusive facies volcaniclastic gas reservoir was first discovered in the Sichuan Basin,which is a major breakthrough in the exploration of volcanic rock gas reservoirs.In order to further evaluate the exploration potential in Permian volcanic rock gas reservoirs in this basin,we systematically reviewed and summarized the exploration process of volcanic rocks in this study area,as well as the characteristics of gas reservoirs of well Yongtan 1,the controlling factors and modes of hydrocarbon accumulation.The following findings were obtained.(1)Over the past five decades of gas exploration of volcanic rocks,the change of exploration thought and progress in seismic prediction contribute to a major discovery in this study area,i.e.,the well location deployment of Yongtan 1 was determined in the Jianyan area,where the volcanic anomalies of the Permian developed outbursts are well developed and the gas reservoir conditions are favorable.This also proves that another new gas exploration area in this basin was found.(2)From the data of Yongtan 1,we found high-quality volcanic porous reservoirs with a thickness of over 100 m developed in the Permian strata,the effusive volcanic rock types dominated by breccia and tuffaceous breccia,reservoir space composed of dissolution pores,interbreccia dissolution pores,and other pores,the porosity of which is 6.68%-13.22%and 10.26%on average,the permeability 0.01-4.43 mD and 2.35 mD on average.(3)This abnormally high pressure gas reservoir was buried 4500-6000 m deep underground with the middle formation pressure being 125.625 MPa and the pressure coefficient being up to 2.22.Methane content in the minor H_(2)S-bearing produced gas flow reached up to 99.03%.(4)Volcanic rocks in the Jianyang-Zhongjiang-Santai area are developed,and they are adjacent to the Cambrian high-quality source rocks in the Deyang-Anyue rifting.The early extensional deep faults play a role in connecting source and storage.There are many sets of caprocks,such as the Upper Permian Longtan Formation and Lower Triassic layered thick paste rocks,providing conditions for forming large-scale tectonic-lithologic composite trap gas reservoirs,and the favorable exploration area reaches up to 6000 km^(2).In conclusion,this major discovery not only proves that Permian volcanic rocks in the Sichuan Basin has large potential for oil and gas exploration,but reaffirms the confidence in changing our exploration thought,speeding up new exploration zones and areas,and discovering more and bigger gas fields.
文摘At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic reservoirs) have been found. Since both the amount and reserve of the discovered subtle reservoirs are small, a great exploration potential remains in the Taibei Sag. The shallow to medium formations in the west of the Taibei Sag were divided into three second-order sequences and ten third-order sequences, of which the rising cyclothems of SQ(J2q) and SQ8 (J2s2) datum level are major exploration targets for the subtle reservoirs (lithologic). The depositional systems of Qiquanhu and Subashi braided river delta were developed there, where the sedimentary sand body is dominated by the regional slopes and slope break belts. There are four main modes the formation of lithologic traps: deltaic front onlap on the slope belt, deltaic front toplap on the slope break belt, lately tilted frontal sand body and sublacustrine fan—slope fan on the slope break belt, of which the first three modes are the major styles of the formation of subtle reservoirs. Major targets for subtle reservoir exploration in the near future include Putaogou Member on the north slope of Huoyanshan, the east slope of Pubei, the nose-like palaeohigh regions of Huobei, Subashi and Lianmuqin, around the Shengbei secondary sag.
文摘The aim of this article is to explore potential directions for the development of artificial intelligence(AI).It points out that,while current AI can handle the statistical properties of complex systems,it has difficulty effectively processing and fully representing their spatiotemporal complexity patterns.The article also discusses a potential path of AI development in the engineering domain.Based on the existing understanding of the principles of multilevel com-plexity,this article suggests that consistency among the logical structures of datasets,AI models,model-building software,and hardware will be an important AI development direction and is worthy of careful consideration.
