2002 Vol. 20, No. 3
column
Display Method:
2002, 20(3): 359-366.
Abstract:
Based on the fundamental principle of StrontiumIsotope Strati graphy(SIS），i.e. strontium isotope composition of seawater is a determined value during the same geological time,we can apply the SISto the research of clastic diagenesis in order to esti matethe effect of marine f acies and non- mari ne facies on diagenesis. three eXamples for t he application from Ahujiangkou Basin,Southern China Sea,ordos Basin,and Bohai wan Basi nare shown as follows ：(1)the composition of stronti umisotope of marine clastic diagenesisfluid developed in a regular pathway.Because of the dissolution of feldspar and other terri genous silicate minerals in diagenesis，the ratio of 87Sr/86Sr of later carbonate cements in diagenesis are usually higher than that of earlier one，and the ori ginal value of the evolution process is the ratio of 87Sr/86Sr of sea water in the same term，which is a determined value.(2)the ratio of 87Sr/86Sr of carbonate cement in terrestrial sandstones may be lower than that of continental meteoric water when the strontiumfromt he mantle influenced the syngenesis water,or the marine facies influenced the diagenesis water by dissolution of older terri genous carbonate rock fragments. However,the ratio of 87Sr/86Sr of carbonate cement preci pitated during later burial diagenesis is also higher than that precipitated during earlier period.(3)When the fluid fromthe mantle controlled the full diagenesis process,and if the inference from mantle strontiumis strong enough to erase or to decrease the difference of strontium isotope composition of various carbonate cements caused by the terrestrial effect in different diagenesis period or different diagenesis degrees，the ratio of87Sr/86Sr of carbonate cements precipitated in different diagenesis periods are all very low and，theref ore，it is lack of the evolution pattern,which often appears in other sedimentary basin,and the ratio of 87Sr/86Sr of carbonate cement precipitated during later burial diagenesis is higher than that precipitated during earlier period.
Based on the fundamental principle of StrontiumIsotope Strati graphy(SIS），i.e. strontium isotope composition of seawater is a determined value during the same geological time,we can apply the SISto the research of clastic diagenesis in order to esti matethe effect of marine f acies and non- mari ne facies on diagenesis. three eXamples for t he application from Ahujiangkou Basin,Southern China Sea,ordos Basin,and Bohai wan Basi nare shown as follows ：(1)the composition of stronti umisotope of marine clastic diagenesisfluid developed in a regular pathway.Because of the dissolution of feldspar and other terri genous silicate minerals in diagenesis，the ratio of 87Sr/86Sr of later carbonate cements in diagenesis are usually higher than that of earlier one，and the ori ginal value of the evolution process is the ratio of 87Sr/86Sr of sea water in the same term，which is a determined value.(2)the ratio of 87Sr/86Sr of carbonate cement in terrestrial sandstones may be lower than that of continental meteoric water when the strontiumfromt he mantle influenced the syngenesis water,or the marine facies influenced the diagenesis water by dissolution of older terri genous carbonate rock fragments. However,the ratio of 87Sr/86Sr of carbonate cement preci pitated during later burial diagenesis is also higher than that precipitated during earlier period.(3)When the fluid fromthe mantle controlled the full diagenesis process,and if the inference from mantle strontiumis strong enough to erase or to decrease the difference of strontium isotope composition of various carbonate cements caused by the terrestrial effect in different diagenesis period or different diagenesis degrees，the ratio of87Sr/86Sr of carbonate cements precipitated in different diagenesis periods are all very low and，theref ore，it is lack of the evolution pattern,which often appears in other sedimentary basin,and the ratio of 87Sr/86Sr of carbonate cement precipitated during later burial diagenesis is higher than that precipitated during earlier period.
2002, 20(3): 376-381.
Abstract:
The relationships of velocity and discharge,water level elevation， sediment concentration and widthdepth ratio of xijiang and beijiang River channels on the zhujiang Delte area are analyzed and some differences between the two rivers are revealed. one of the differences is that the channel cross sections are different between the two rivers either in width- dept h ratio or in channel evolution despite the planf or mof the two rivers appears multiple channel system. The author considered that all the xijiang River channels and the beijiang channels at b and C belts on the Delta area are anastomosi ng pattern,but the beijiang River channels at A belt are not anastomosing river pattern. The xijiang anastomosing channels are typical and developed,and the beijiang anastomosing channels still are at the primary developing stage. The anastomosing channel for mation follows the channel avulsion mechanismduring flooding as Smith (1989)stated. However,the freCuency of channel avulsion is veryrare， so the anastomosi ng channel for mation has a long history. The anastomosing channels have cohesive natural levees that were consisted of fine grain sediment such as clay or mud. Artificial levees did not the for mation cause of the anastomosing channel pattern. Nevertheless it not only restrained the migration of the channels and maintained the channel stability but also partly prevented flooding. This human behavior resulted the high sedimentary ratio in the anastomosing channels and lower sedimentary ratio on the interchannel lands. So the relative rising velocity of the anastomosing channel beds is greater than that of the interchannel lands.
The relationships of velocity and discharge,water level elevation， sediment concentration and widthdepth ratio of xijiang and beijiang River channels on the zhujiang Delte area are analyzed and some differences between the two rivers are revealed. one of the differences is that the channel cross sections are different between the two rivers either in width- dept h ratio or in channel evolution despite the planf or mof the two rivers appears multiple channel system. The author considered that all the xijiang River channels and the beijiang channels at b and C belts on the Delta area are anastomosi ng pattern,but the beijiang River channels at A belt are not anastomosing river pattern. The xijiang anastomosing channels are typical and developed,and the beijiang anastomosing channels still are at the primary developing stage. The anastomosing channel for mation follows the channel avulsion mechanismduring flooding as Smith (1989)stated. However,the freCuency of channel avulsion is veryrare， so the anastomosi ng channel for mation has a long history. The anastomosing channels have cohesive natural levees that were consisted of fine grain sediment such as clay or mud. Artificial levees did not the for mation cause of the anastomosing channel pattern. Nevertheless it not only restrained the migration of the channels and maintained the channel stability but also partly prevented flooding. This human behavior resulted the high sedimentary ratio in the anastomosing channels and lower sedimentary ratio on the interchannel lands. So the relative rising velocity of the anastomosing channel beds is greater than that of the interchannel lands.
2002, 20(3): 409-415.
Abstract:
Based on the geological and geophysical data,the authors summarized the applied seCuence strati graphy of non- marine basins in China. the controls on non- mari ne seCuences included both allocyclic and autocyclic processes. the most important factors Were tectonics and climate,but the environmental factor Would also be taken into account. the accommodation changed periodically With changing base level,resulting in the for mation of a series of genetically and spatially related depositional seCuences. Basically,base level of inner continent Was not controlled by changes of relative sea level. there Would be some relations bet Ween changes in relative sea level and continental base level during eustacy floodi ng,hoWever,a time lag existed betWeen the changes from marine basin to inner continent basin. the lake basin Was smaller than marine basin and the velocity of sedimentary supply Was higher, so the numbers of non- marine seCuences Were much more than those for med in marine facies during the same period. We have to pay attention to recognizing the systems tracts f or t he st udy of hi gh precision or hi gh-resolution seCuence strati graphy,especially to analyze t he loWstand systems tract Wit h its depositional systems. The genetic characteristics of seCuence boundary Were subaerial exposure,strati graphic truncation and subaCuatic erosion. According to the depositional feat ures of Zhanhua Depression,5 seCuence architect ures have been provi ded in this paper,Which are alluvial-fluvial/lacustri ne architecture，transitional architecture formed betWeen brackish lake and fresh lake,marine duration- deep lacustrine architecture，ramp architecture and fluvial-alluvial plain architecture. During the major development of non- marine basin，the step faulting breaks controlled depositional systems.Usually,loWstand complex fan,progradi ng Wedge and highstand turbidity f an Were located close to the third stepping break,it Was bypass of incised valley in loWstand period and then filled With adj acent sandy bar by the second stepping break,and at the first stepping break the sedi ments Were bypass Which could form favorable subtle or complex traps as the basin floor fan,and their economic significance Would be proved by boreholes in Bohai Bay Basin.
Based on the geological and geophysical data,the authors summarized the applied seCuence strati graphy of non- marine basins in China. the controls on non- mari ne seCuences included both allocyclic and autocyclic processes. the most important factors Were tectonics and climate,but the environmental factor Would also be taken into account. the accommodation changed periodically With changing base level,resulting in the for mation of a series of genetically and spatially related depositional seCuences. Basically,base level of inner continent Was not controlled by changes of relative sea level. there Would be some relations bet Ween changes in relative sea level and continental base level during eustacy floodi ng,hoWever,a time lag existed betWeen the changes from marine basin to inner continent basin. the lake basin Was smaller than marine basin and the velocity of sedimentary supply Was higher, so the numbers of non- marine seCuences Were much more than those for med in marine facies during the same period. We have to pay attention to recognizing the systems tracts f or t he st udy of hi gh precision or hi gh-resolution seCuence strati graphy,especially to analyze t he loWstand systems tract Wit h its depositional systems. The genetic characteristics of seCuence boundary Were subaerial exposure,strati graphic truncation and subaCuatic erosion. According to the depositional feat ures of Zhanhua Depression,5 seCuence architect ures have been provi ded in this paper,Which are alluvial-fluvial/lacustri ne architecture，transitional architecture formed betWeen brackish lake and fresh lake,marine duration- deep lacustrine architecture，ramp architecture and fluvial-alluvial plain architecture. During the major development of non- marine basin，the step faulting breaks controlled depositional systems.Usually,loWstand complex fan,progradi ng Wedge and highstand turbidity f an Were located close to the third stepping break,it Was bypass of incised valley in loWstand period and then filled With adj acent sandy bar by the second stepping break,and at the first stepping break the sedi ments Were bypass Which could form favorable subtle or complex traps as the basin floor fan,and their economic significance Would be proved by boreholes in Bohai Bay Basin.
2002, 20(3): 421-426.
Abstract:
Accurate determination of sedimentation boundary age in recent lake is a basic work relevant to environmental investigation. based on the relationship of two industrial events and type of magnetic substance,magnetic suscepti bility,depositional characteristics in five cores from the east Lake,Wuhan,Hubei,China,the changes of sedimentation rate have been recognized during a period of past 110 years and t wo historically events in A. D. 1740 and 1810. the boundaries be ween the layers attributed to changes in industrial activity around the lake. the study illustrates the value of magnetic suscepti bility for identifying time planes in recent sediments,and obtains the difference of sedimentation rates in different period and，furthermore,discusses the cause of magnetic susceptibility influenced by the charge of magnetic substance.
Accurate determination of sedimentation boundary age in recent lake is a basic work relevant to environmental investigation. based on the relationship of two industrial events and type of magnetic substance,magnetic suscepti bility,depositional characteristics in five cores from the east Lake,Wuhan,Hubei,China,the changes of sedimentation rate have been recognized during a period of past 110 years and t wo historically events in A. D. 1740 and 1810. the boundaries be ween the layers attributed to changes in industrial activity around the lake. the study illustrates the value of magnetic suscepti bility for identifying time planes in recent sediments,and obtains the difference of sedimentation rates in different period and，furthermore,discusses the cause of magnetic susceptibility influenced by the charge of magnetic substance.
2002, 20(3): 442-446.
Abstract:
Through a combined analysis of sedimentary characteristics,C and Oisotopes,Mg and Sr trace elements of a stalagmite from Heshang Cave,Hubei,Wit h urani um-series dating，t he palaeoclimatic and palaeoenvironmental Information from19.0ka to 6.9ka i n the Hubei area is obtained.The average resolution is 17a,and t he local resolution is 7a. The following results are obtained ：(1)f rom 19.0 ~16.6ka B.P. ：C and Oisotopes Were lighter,the climate Was cold and Wet ；(2)16.6 ~11.1kaB.P. ：C，Oisotopes Were a little heavy,temperature rose,r ain fall Was inclined to be little ；(3)11.1 ~10.3ka B.P. ：an excursion during dry and hot period responded to the Younger Dryas Event ；(4)10.3 ~6.9 ka B.P：C，O，I sotopes Were lighter,but Mg/Sr value Was bigger,showing temperature Was continuously rising and rain f all Was greater. These reflect the variation tends from humid-cold climate，to dry- hot climate，and to humid,War mcli mate in history,and some climatic variation trends of thousand years and hundred years cycles are gainned. I n particular the authors found out the integrated record of the Younger Dryas Event Which means the Younger Dryas Event is a globally climatic sudden change and environmental calamity.
Through a combined analysis of sedimentary characteristics,C and Oisotopes,Mg and Sr trace elements of a stalagmite from Heshang Cave,Hubei,Wit h urani um-series dating，t he palaeoclimatic and palaeoenvironmental Information from19.0ka to 6.9ka i n the Hubei area is obtained.The average resolution is 17a,and t he local resolution is 7a. The following results are obtained ：(1)f rom 19.0 ~16.6ka B.P. ：C and Oisotopes Were lighter,the climate Was cold and Wet ；(2)16.6 ~11.1kaB.P. ：C，Oisotopes Were a little heavy,temperature rose,r ain fall Was inclined to be little ；(3)11.1 ~10.3ka B.P. ：an excursion during dry and hot period responded to the Younger Dryas Event ；(4)10.3 ~6.9 ka B.P：C，O，I sotopes Were lighter,but Mg/Sr value Was bigger,showing temperature Was continuously rising and rain f all Was greater. These reflect the variation tends from humid-cold climate，to dry- hot climate，and to humid,War mcli mate in history,and some climatic variation trends of thousand years and hundred years cycles are gainned. I n particular the authors found out the integrated record of the Younger Dryas Event Which means the Younger Dryas Event is a globally climatic sudden change and environmental calamity.
2002, 20(3): 456-461.
Abstract:
The correlation of crude oil and its source rocks in the Turpan- Hami basin is made based on the geochemical parameters，such as biomarkers and carbon isotopes The result shoWs that the crude oil from the Tupan-Hami basin can be classified into three.According to the analysis of biomarkers，the first type of oil referring an obvious fresh Water environment,lower content of algae，great influence of bacteria, high content of C29sterane，low content of C304α- methylsterane high content of C24tetracyclic and C19trcyclic terpanes，and heavier carbon isotopes(δ13Cranges from -25 %to -27 %）.According to the correlation of crude oil and source rocks，the coal of Xishanyao For mation is the main source rock of the oil.The second type of oil is characterized by high content of algal substance(high content of C27 and C304α-methylstrane)，and this kind of oil is possi bly fromthe lacustrine mudstone With abundant algae.The carbon isotope of the third type of oil ranges from -30 %to -32 %，and its biomarkers reflect that the source rock is a kind of anoxic and salty lacustrine sedi ments(Ithas high contents of gammacerane and $- phyllocladane，and high ratio of C35/C34hopanes.
The correlation of crude oil and its source rocks in the Turpan- Hami basin is made based on the geochemical parameters，such as biomarkers and carbon isotopes The result shoWs that the crude oil from the Tupan-Hami basin can be classified into three.According to the analysis of biomarkers，the first type of oil referring an obvious fresh Water environment,lower content of algae，great influence of bacteria, high content of C29sterane，low content of C304α- methylsterane high content of C24tetracyclic and C19trcyclic terpanes，and heavier carbon isotopes(δ13Cranges from -25 %to -27 %）.According to the correlation of crude oil and source rocks，the coal of Xishanyao For mation is the main source rock of the oil.The second type of oil is characterized by high content of algal substance(high content of C27 and C304α-methylstrane)，and this kind of oil is possi bly fromthe lacustrine mudstone With abundant algae.The carbon isotope of the third type of oil ranges from -30 %to -32 %，and its biomarkers reflect that the source rock is a kind of anoxic and salty lacustrine sedi ments(Ithas high contents of gammacerane and $- phyllocladane，and high ratio of C35/C34hopanes.
2002, 20(3): 469-476.
Abstract:
Depositional settings of the upper Triassic of Chuxiong basin are f aVorable f or the deep basin gas accumulation. The fluVial and deltaic deposits constitute the dominated reserVoir in the deep basin. The numerous and mature coal beds and organic-rich shales associated inti mately With reserVoir rocks throughout the deep basin pro-Vide a prereCuisite f or deep basin gas accumulation. Gas has the tendency to be trapped in the deepest part of the basin and probably occupies loW per meability reserVoirs extensiVely. Gas generated in source rocks,moVed into the adj acent sand layer and then sloWly migrated updi p. The filling process of deep basin gas asted fromthe late Cretaceous to mid- Tertiary time. Gas may be located doWndip of an aCuifer Which outcrops in basin margins. The gas accumulation of the upper Triassic of Chuxiong basin is predicted and interpreted based on the trapping mechanism of deep basin gas reserVoir. The distribution of deep basin gas accumulation in the basin is descri bed according to the key parameters controlling the ulti mate trapping.
Depositional settings of the upper Triassic of Chuxiong basin are f aVorable f or the deep basin gas accumulation. The fluVial and deltaic deposits constitute the dominated reserVoir in the deep basin. The numerous and mature coal beds and organic-rich shales associated inti mately With reserVoir rocks throughout the deep basin pro-Vide a prereCuisite f or deep basin gas accumulation. Gas has the tendency to be trapped in the deepest part of the basin and probably occupies loW per meability reserVoirs extensiVely. Gas generated in source rocks,moVed into the adj acent sand layer and then sloWly migrated updi p. The filling process of deep basin gas asted fromthe late Cretaceous to mid- Tertiary time. Gas may be located doWndip of an aCuifer Which outcrops in basin margins. The gas accumulation of the upper Triassic of Chuxiong basin is predicted and interpreted based on the trapping mechanism of deep basin gas reserVoir. The distribution of deep basin gas accumulation in the basin is descri bed according to the key parameters controlling the ulti mate trapping.
2002, 20(3): 482-487.
Abstract:
Abstract the carbon isotopic compositions of hydrocarbon series were measured from natural gases in the Northern and central tari m basin . any local turnover phenomena,e.g. δ13c1 ＞δ13c2＞δ13c3 or δ13c1 ＞δ13c2＞δ13c3＞δ13c4，exist in the carbon isotopic compositions of hydrocarbon series. they suggests thathydrocarbons of the natural gases may be mainly biogenic in the Northern and central tarim basin. ost of natural gas samples have the turnovers of δ13 c3 ＞δ13 c4 from the Northern Slope Zone in the Luntai uplift,and the cause of the turnovers may be that these natural gases were mixed less amount of sapropelic hydrocarbons. according to δ13c1values of natural gases and whether they have the δ13c1 ＞δ13c2 turnover,natural gases in the central tarim basin can be divided in to two groups. Natural gases of the first group have heavy δ13c1 values,bet ween -2l.l %"-30.7 %，and the13c1＞δ13c2turnover,such as tz26(0)well,tzl03(cⅡ）well and tzl03(cⅢ）well ；the others have light δl3c1，δl3c2 values,with -4l.0 %"-43.7 %，and -38.8 %"-39.6 %，respectively,without the δ13c1 ＞δ13c2 turnover,such as t24sp-3(cⅢ），tz4-8-30(cⅢ），tz-l(0)and tz45(0)well. t may suggest that less amount of abiogenic hydrocarbons was contained in natural gases of the first group,and that natural gases in the central tarim basin have two genetic types. all the natural gases do not exist turnover of carbon isotopic compositions fromthe Lunnan Lower- uplift,suggesting that they may come from the same source.
Abstract the carbon isotopic compositions of hydrocarbon series were measured from natural gases in the Northern and central tari m basin . any local turnover phenomena,e.g. δ13c1 ＞δ13c2＞δ13c3 or δ13c1 ＞δ13c2＞δ13c3＞δ13c4，exist in the carbon isotopic compositions of hydrocarbon series. they suggests thathydrocarbons of the natural gases may be mainly biogenic in the Northern and central tarim basin. ost of natural gas samples have the turnovers of δ13 c3 ＞δ13 c4 from the Northern Slope Zone in the Luntai uplift,and the cause of the turnovers may be that these natural gases were mixed less amount of sapropelic hydrocarbons. according to δ13c1values of natural gases and whether they have the δ13c1 ＞δ13c2 turnover,natural gases in the central tarim basin can be divided in to two groups. Natural gases of the first group have heavy δ13c1 values,bet ween -2l.l %"-30.7 %，and the13c1＞δ13c2turnover,such as tz26(0)well,tzl03(cⅡ）well and tzl03(cⅢ）well ；the others have light δl3c1，δl3c2 values,with -4l.0 %"-43.7 %，and -38.8 %"-39.6 %，respectively,without the δ13c1 ＞δ13c2 turnover,such as t24sp-3(cⅢ），tz4-8-30(cⅢ），tz-l(0)and tz45(0)well. t may suggest that less amount of abiogenic hydrocarbons was contained in natural gases of the first group,and that natural gases in the central tarim basin have two genetic types. all the natural gases do not exist turnover of carbon isotopic compositions fromthe Lunnan Lower- uplift,suggesting that they may come from the same source.
2002, 20(3): 493-498.
Abstract:
The model system，Which is an incomplete three- dimensional model (X，Y，vertical geological layers and time)about the buried history and the maturity history of source rock in Liaohe Basin，is built and programmed. The model simulates the buried history of every depression by the Backstrip ping method While the unconformity is considered. The Ro evolution progress of source rock is simulated by TTI-Ro relationship after the TTI history is calculated With the paleo-temperature gradients. So，the maturity history is reconstructed. According to the result of model system，there are two deposit centers of East Depression,Which are Niuju and Gaolifang- Yongxingtun area,two deposit centers of West Depression,Which are Taian and Panshan- DaCingshuigou area,also two deposit centers of Damintun Depression,Which are Rongshengbao and the North area of Jinganbao.And Es3 of East Depression,Es4 and Es3 of West Depression,Es4 and Es3 of Damintun Depression,Which have been in oil Window，are main source layers of Liaohe Basin.
The model system，Which is an incomplete three- dimensional model (X，Y，vertical geological layers and time)about the buried history and the maturity history of source rock in Liaohe Basin，is built and programmed. The model simulates the buried history of every depression by the Backstrip ping method While the unconformity is considered. The Ro evolution progress of source rock is simulated by TTI-Ro relationship after the TTI history is calculated With the paleo-temperature gradients. So，the maturity history is reconstructed. According to the result of model system，there are two deposit centers of East Depression,Which are Niuju and Gaolifang- Yongxingtun area,two deposit centers of West Depression,Which are Taian and Panshan- DaCingshuigou area,also two deposit centers of Damintun Depression,Which are Rongshengbao and the North area of Jinganbao.And Es3 of East Depression,Es4 and Es3 of West Depression,Es4 and Es3 of Damintun Depression,Which have been in oil Window，are main source layers of Liaohe Basin.
Carbon Isotopic Composition and Yield of Gaseous Hydrocarbon by Oil Hydrous Pyrolysis in Rock Medium
2002, 20(3): 505-509.
Abstract:
Hydrous pyrolysis experiments of generating gas from the mixture of oil- Water and reservoir rocks have been caried out in a closed system，the samples are derived from deep layer of the Songliao basin.the results show that yield Cuantities of gaseous hydrcarbon is very small at temperature below350℃，Which mainly derived from oil evaporation. when simulating temperature reaches 400℃，large Cuantities of gas are generated from oil. with increasing of temperature the proprtion of methane in the generated gas increases,While the heavier components decrease particularly the propane.the range of temperature for gas largely generated from the mixture of oil - Water sandstone is 450~500℃，While the range from the mixture of oil —Water and igneous rocks is 450~600℃. The Cuantities of gaseous hydrocarbon generated from both settings are similar and about 17m3/t oil at the end，but the hydrocarbon yield is different at each temperature point.the maximal yield at 5 Cis respectively 78.67m3/t oil abd 66.11m3/t oil for the two experiments hydrolysis and catalysis may be an important influence on the composition and yield of the simulated gas.the experiment also shows that δ13Cvalues of the gas generated from the experiment at temperature between 400~450℃(Ro approximately 1.3 % ~1.8 %)are relatively lower than that of gas derived from kerogen，and δ13C1 is -5.86 %~-48.43 %. when the temperature increases to 550~600℃(Ro approximately 2.8 % ~3.4 %)，δ13C of the gas brcomes reativly higher than that of gas derived from kerogen，and kerogen，and δ13C1 is -39.61 %~-24.26 %.this fact indicates that fractionation of carbon isotopon of gas from the experiment is stronger than the gas directly derived from kerogen.the regular sequence of carbon isotope has been found at temperature between 400~450℃Ci.e.δ13C1＜δ13C2＜δ13C3＜δ13C4.but partial opposites sequence of carbon isotope appeared at temperature above 500℃，the sequence is δ13C1δ13C2＜δ13C3＜δ13C4. Comparing the carbon isotopic composition between the mixture of oil- Water and sandstone and the mixture of oil- Water and igneous rocks，the latter is lighter 1.2 %~4.2 %than the fromer at the temperature of 400~450℃ and heavier at the temperature above 550℃，Which show a different influence of catalysis in various medium.this result is useful for identifying the origin and maturation of nature gas for the deep layer of the Songliao basin.
Hydrous pyrolysis experiments of generating gas from the mixture of oil- Water and reservoir rocks have been caried out in a closed system，the samples are derived from deep layer of the Songliao basin.the results show that yield Cuantities of gaseous hydrcarbon is very small at temperature below350℃，Which mainly derived from oil evaporation. when simulating temperature reaches 400℃，large Cuantities of gas are generated from oil. with increasing of temperature the proprtion of methane in the generated gas increases,While the heavier components decrease particularly the propane.the range of temperature for gas largely generated from the mixture of oil - Water sandstone is 450~500℃，While the range from the mixture of oil —Water and igneous rocks is 450~600℃. The Cuantities of gaseous hydrocarbon generated from both settings are similar and about 17m3/t oil at the end，but the hydrocarbon yield is different at each temperature point.the maximal yield at 5 Cis respectively 78.67m3/t oil abd 66.11m3/t oil for the two experiments hydrolysis and catalysis may be an important influence on the composition and yield of the simulated gas.the experiment also shows that δ13Cvalues of the gas generated from the experiment at temperature between 400~450℃(Ro approximately 1.3 % ~1.8 %)are relatively lower than that of gas derived from kerogen，and δ13C1 is -5.86 %~-48.43 %. when the temperature increases to 550~600℃(Ro approximately 2.8 % ~3.4 %)，δ13C of the gas brcomes reativly higher than that of gas derived from kerogen，and kerogen，and δ13C1 is -39.61 %~-24.26 %.this fact indicates that fractionation of carbon isotopon of gas from the experiment is stronger than the gas directly derived from kerogen.the regular sequence of carbon isotope has been found at temperature between 400~450℃Ci.e.δ13C1＜δ13C2＜δ13C3＜δ13C4.but partial opposites sequence of carbon isotope appeared at temperature above 500℃，the sequence is δ13C1δ13C2＜δ13C3＜δ13C4. Comparing the carbon isotopic composition between the mixture of oil- Water and sandstone and the mixture of oil- Water and igneous rocks，the latter is lighter 1.2 %~4.2 %than the fromer at the temperature of 400~450℃ and heavier at the temperature above 550℃，Which show a different influence of catalysis in various medium.this result is useful for identifying the origin and maturation of nature gas for the deep layer of the Songliao basin.
2002, 20(3): 515-518.
Abstract:
The relationship bet ween viscosity and saturate,aromatic compounds of 21 oil samples in Leng43/37 blocks,Liaohe Oil Field was studied based on TLC- FI Danalysis and solvent selective extracting-Cuantitatively GC/MS analysis. Oil viscosity increases while saturate bulk composition decreases. Moreover,oil viscosity has close relationship with the absolute concentrate of naphthalene,phenanthrene and dibenzothiophene compounds and their percentage in aromatics rather than aromatic gross composition. The relationship bet ween viscosity and aromatic compounds shows a changing trend with viscosity. Aseries of models were primarily constructed to predict the viscosity of biodegraded oil in this paper.
The relationship bet ween viscosity and saturate,aromatic compounds of 21 oil samples in Leng43/37 blocks,Liaohe Oil Field was studied based on TLC- FI Danalysis and solvent selective extracting-Cuantitatively GC/MS analysis. Oil viscosity increases while saturate bulk composition decreases. Moreover,oil viscosity has close relationship with the absolute concentrate of naphthalene,phenanthrene and dibenzothiophene compounds and their percentage in aromatics rather than aromatic gross composition. The relationship bet ween viscosity and aromatic compounds shows a changing trend with viscosity. Aseries of models were primarily constructed to predict the viscosity of biodegraded oil in this paper.
2002, 20(3): 524-528.
Abstract:
One hundred and eighty-three species of fossil spores and pollen were identified，that are referred to 89 genera found in 44 crude oil samples and 3 natural gas samples collected fromthe North Tarim，Kuche,Kashi and Yecheng petroliferous regions of Tarim Basin. Based on the investigations of the fossil spores and pollen found in oil and gas，the mechanisms of petroleum migration were discussed according to the geological background of the basin. The contents of this study include the passages,phase states,directions，routes and periodic sequences of petroleum migration. Judging from the spores and pollen in petroleum，it may be concluded that microfissures for med by abnormal high pressure during the diagenesis of petroleumsource rocks could provide passages for the primary migration of petroleum；faults,unconformity surf aces，joints and other fissures could be the passages of the secondary migration of petroleum；petroleum might keep in the original phase state in the course of migration,and liquid and gaseous mixed phase might be the main phase state in the course of petroleum migration in Tarim Basin ；and the main direction of petroleum migration could be represented by either vertical migration or lateral migration for different reservoir types.
One hundred and eighty-three species of fossil spores and pollen were identified，that are referred to 89 genera found in 44 crude oil samples and 3 natural gas samples collected fromthe North Tarim，Kuche,Kashi and Yecheng petroliferous regions of Tarim Basin. Based on the investigations of the fossil spores and pollen found in oil and gas，the mechanisms of petroleum migration were discussed according to the geological background of the basin. The contents of this study include the passages,phase states,directions，routes and periodic sequences of petroleum migration. Judging from the spores and pollen in petroleum，it may be concluded that microfissures for med by abnormal high pressure during the diagenesis of petroleumsource rocks could provide passages for the primary migration of petroleum；faults,unconformity surf aces，joints and other fissures could be the passages of the secondary migration of petroleum；petroleum might keep in the original phase state in the course of migration,and liquid and gaseous mixed phase might be the main phase state in the course of petroleum migration in Tarim Basin ；and the main direction of petroleum migration could be represented by either vertical migration or lateral migration for different reservoir types.
2002, 20(3): 367-375.
Abstract:
On the basis of discussing the paleogeographic reconstruction,the change of lithology and biota through t he section，the cycles of Ce anormaly and the indicating biota for depth of water mass fromt he latest Ordovician in the Yangtze Basin，the author holds that 5 eustatic cycles in the latest Ordovician Wufengian and that,the depth of water mass is at least 50 to 80 metres(respect to Guanyinqiao Bed)and at most 500 metres or so.
On the basis of discussing the paleogeographic reconstruction,the change of lithology and biota through t he section，the cycles of Ce anormaly and the indicating biota for depth of water mass fromt he latest Ordovician in the Yangtze Basin，the author holds that 5 eustatic cycles in the latest Ordovician Wufengian and that,the depth of water mass is at least 50 to 80 metres(respect to Guanyinqiao Bed)and at most 500 metres or so.
2002, 20(3): 394-398.
Abstract:
New data on osmiumisotopic compositions of four seafloor massive sulfide samples from the TAG hydrothermal field has been got,the 187Os/186Os ratios of massive sulfide samples vary from2.305 to 7.879,with a mean of 5.986,these ratios are bet ween that of modern seawater and upper oceanic crust,and this range of Os isotopic compositions is likely the result of mixing of seawater with upper oceanic crust,maybe about 56 % of osmium in the massive sulfides is from the seawater,and 44 % is fromt he upper oceanic crust. The mixing of seawater with hydrothermal fluid have an obvious effect on the Os concentration and isotope composition of massive sulfi de during the seafloor hydrothermal activity.
New data on osmiumisotopic compositions of four seafloor massive sulfide samples from the TAG hydrothermal field has been got,the 187Os/186Os ratios of massive sulfide samples vary from2.305 to 7.879,with a mean of 5.986,these ratios are bet ween that of modern seawater and upper oceanic crust,and this range of Os isotopic compositions is likely the result of mixing of seawater with upper oceanic crust,maybe about 56 % of osmium in the massive sulfides is from the seawater,and 44 % is fromt he upper oceanic crust. The mixing of seawater with hydrothermal fluid have an obvious effect on the Os concentration and isotope composition of massive sulfi de during the seafloor hydrothermal activity.
2002, 20(3): 400-407.
Abstract:
Based on the analysis of outcrops,well logs and high resolution seismic reflection data,this paper tries to interpret the depositional enVironment and the seCuence stratigraphy of Jurassic in Kuche depression. The results show that the Kuche basin is a non-symmetry depression basin,of which the proVenance is from the north. There are 13 third seCuences and 3 seCuence beds,which are t he results of 3 cycles. The large lake transgression is the middle upper of Yangxia For mation,which is consistent to the hot climate. The enVironment is the braided riVer,meandering riVer- delta,and delta and shallowlake,with the ephemeral sea transgression. The source rock is well distributed in the ephemeral sea transgression and the large lake transgression in the middle Jurassic. the reservoir distribution is the key factor to forming oil and gas accumulation.the river reservoir heterogeneity is controlled by the terrestrial environment,although t here are the Well distri bution of the sandbody and great reservoir thickness.
Based on the analysis of outcrops,well logs and high resolution seismic reflection data,this paper tries to interpret the depositional enVironment and the seCuence stratigraphy of Jurassic in Kuche depression. The results show that the Kuche basin is a non-symmetry depression basin,of which the proVenance is from the north. There are 13 third seCuences and 3 seCuence beds,which are t he results of 3 cycles. The large lake transgression is the middle upper of Yangxia For mation,which is consistent to the hot climate. The enVironment is the braided riVer,meandering riVer- delta,and delta and shallowlake,with the ephemeral sea transgression. The source rock is well distributed in the ephemeral sea transgression and the large lake transgression in the middle Jurassic. the reservoir distribution is the key factor to forming oil and gas accumulation.the river reservoir heterogeneity is controlled by the terrestrial environment,although t here are the Well distri bution of the sandbody and great reservoir thickness.
2002, 20(3): 416-420.
Abstract:
Phosphorus is an important element Which produces eutrophication in lake sediment. People have paid special attention to the phosphorous research according to its content and geochemical activity as Well as complenmineral characteristics in the lake. the total content of phosphorus i n Dianchi lake is 10.3 times as high as normal data. the average content of P2o5 in bottom mud is 0.52 %,and t he highest content reaches 1.92 %. there are many phosphorus mineral deposits， so the source of phosphorus in the lake is very rich. on the basis of statistics,the phosphorus content has been increasi ng every year. the existi ng for ms of phosphorus in Dianchi sediment are mainly in adsorbed form，organic for m and combi ned With Fe,Ca,Al and Sb. these forms of phosphorus in the bottom mud are not stable， easily changing With environment,so phosphorus can be released into the Water body again. Microorganisms play an important role in t he circuation of phosphorus，l actate bacteria can resolve phosphate and make the content of soluble phosphorus increase in the lake. the enrichment of phosphorus can be due to assemble phosphorus bacteria and, after they die，the mineralization of the organic phosphorus is important Way Which result in hydrated phosphate deposit in the lake. When conditions are suitable，the unsteady hydrated phosphate is covered by sediment,after mineralization，it Will become apatite in the end.
Phosphorus is an important element Which produces eutrophication in lake sediment. People have paid special attention to the phosphorous research according to its content and geochemical activity as Well as complenmineral characteristics in the lake. the total content of phosphorus i n Dianchi lake is 10.3 times as high as normal data. the average content of P2o5 in bottom mud is 0.52 %,and t he highest content reaches 1.92 %. there are many phosphorus mineral deposits， so the source of phosphorus in the lake is very rich. on the basis of statistics,the phosphorus content has been increasi ng every year. the existi ng for ms of phosphorus in Dianchi sediment are mainly in adsorbed form，organic for m and combi ned With Fe,Ca,Al and Sb. these forms of phosphorus in the bottom mud are not stable， easily changing With environment,so phosphorus can be released into the Water body again. Microorganisms play an important role in t he circuation of phosphorus，l actate bacteria can resolve phosphate and make the content of soluble phosphorus increase in the lake. the enrichment of phosphorus can be due to assemble phosphorus bacteria and, after they die，the mineralization of the organic phosphorus is important Way Which result in hydrated phosphate deposit in the lake. When conditions are suitable，the unsteady hydrated phosphate is covered by sediment,after mineralization，it Will become apatite in the end.
2002, 20(3): 435-441.
Abstract:
Stalagmite is a typical dripstone shape of CaC03 in caves and the most comprehensive and systematical paleoclimate environment in for mation carrier too. With advances of dating techniCues and analytic methods with high resolution，it is of great significance in the paleoclimate environment reconstruction. The combi nation，thickness，grain size and bedding plane structure of depositional laminae in stalagmite are the material base to resume droping water trends of for ming stalagmite and the related paleo- hydrological conditions. 0n the basis of the analysis and study of many stalagmite vertical profiles and systematic isotopic compositions,trace elements and specific laminae，it has been demonstrated that stalagime sedimentary laminae have obvious rhythmic combination,sedimentary cycles and indication of paleoclimatic environments. It is firstly put for ward that stalagmite is of lamina groups of cone in cone,cone and pillar,cone i n cone and pillar combined types and with the sediment ary structures,such as continuity,cycle,disconnected and compound lamina types. The paper discusses their indivitual charatersitics，trends of dropping and flow water and evolutionary characteristics of climatic environments.
Stalagmite is a typical dripstone shape of CaC03 in caves and the most comprehensive and systematical paleoclimate environment in for mation carrier too. With advances of dating techniCues and analytic methods with high resolution，it is of great significance in the paleoclimate environment reconstruction. The combi nation，thickness，grain size and bedding plane structure of depositional laminae in stalagmite are the material base to resume droping water trends of for ming stalagmite and the related paleo- hydrological conditions. 0n the basis of the analysis and study of many stalagmite vertical profiles and systematic isotopic compositions,trace elements and specific laminae，it has been demonstrated that stalagime sedimentary laminae have obvious rhythmic combination,sedimentary cycles and indication of paleoclimatic environments. It is firstly put for ward that stalagmite is of lamina groups of cone in cone,cone and pillar,cone i n cone and pillar combined types and with the sediment ary structures,such as continuity,cycle,disconnected and compound lamina types. The paper discusses their indivitual charatersitics，trends of dropping and flow water and evolutionary characteristics of climatic environments.
2002, 20(3): 447-455.
Abstract:
West gases transporting to the east China is one of huge proj ects related to the development on the west China.The amount of first transportation gas that is 120 billion m3 will be provi ded by four basins in the western China especially Tari m basin.The remnant gas excavated in the basin is 3 397 > 108m3， basically satisf y the demand reCuired by the first phase of the proj ect.To provi de such enor mous resources is still in need of arduous assignment of geologists.The geochemical study on four basins,mainly including large- mi ddle basins，is very significant for reaching this goal. The results showthat the nat ural gas fromcoal was mostly generated in several foreland basins in Tarimin basin,China ；and the gas from high rank oil of Chuandong region existed mainly in Sichuan basin,China ；the natural gases of platform basin are the gas fromcoal and the composite gas from high-excessive rank oil gas and coal in Ordos basin China ；the gas of the Gai dam basin mainly came fromthe lowrank gas from coal.The resource potential is optimistic in the first three basins where may be found more than trillion cubic meter natural gas in the near furure.They will contribute to not only the west gases transporting to east region project, but also to our natural gas industry,and the amount of natural gas will be increased more than 500 billion m3 and 1000 billion m3 in the future five and fifteen years，respectively.
West gases transporting to the east China is one of huge proj ects related to the development on the west China.The amount of first transportation gas that is 120 billion m3 will be provi ded by four basins in the western China especially Tari m basin.The remnant gas excavated in the basin is 3 397 > 108m3， basically satisf y the demand reCuired by the first phase of the proj ect.To provi de such enor mous resources is still in need of arduous assignment of geologists.The geochemical study on four basins,mainly including large- mi ddle basins，is very significant for reaching this goal. The results showthat the nat ural gas fromcoal was mostly generated in several foreland basins in Tarimin basin,China ；and the gas from high rank oil of Chuandong region existed mainly in Sichuan basin,China ；the natural gases of platform basin are the gas fromcoal and the composite gas from high-excessive rank oil gas and coal in Ordos basin China ；the gas of the Gai dam basin mainly came fromthe lowrank gas from coal.The resource potential is optimistic in the first three basins where may be found more than trillion cubic meter natural gas in the near furure.They will contribute to not only the west gases transporting to east region project, but also to our natural gas industry,and the amount of natural gas will be increased more than 500 billion m3 and 1000 billion m3 in the future five and fifteen years，respectively.
2002, 20(3): 462-468.
Abstract:
There is great biogas potential in the Guaternary and Pliocene of the Yinggehai Basin. The compositions of gases f ound in the Basin are mainly methane and nitrogen. These biogases are characterized by high dry coefficients(C1/C1-5ratio)of 0.99, light carbon isotopes of methane(-65.57 %!-63.14 %）， especially heavy hydrogen isotopic values("Dc1%）of -172. 1 %!-108. 5 %. Geochemical data show that the Guaternary and Pliocene mud has the meanTOC value of 0.4 % and contains abundant organic matter which can be degraded by bacteria. The organic matter mainly consists of coarse-fi ber,semi-fiber and protein.Noticeably,it contains a high content of amino acid that is an inter mediate product during the f or mation process of biogas. This indicates that the mudstone in the Guaternary and Pliocene of the Basin is f avourable to biogas f or mation and is good biogas sourcerock.The data of modeling eXperi ment,combined with the gas measurement log and geotemperat ure gradient data of the basin,can be used to predict that the main stage of bio-gas generation is bet ween 35 C and 65 C and the death temperat ure of bio-gases is about 85 C(eCuivalent with the burial depth of around 1 900 min the Basin）.Finally，we suggest the generation-evolution model of marine biogas in the Yinggehai basin.
There is great biogas potential in the Guaternary and Pliocene of the Yinggehai Basin. The compositions of gases f ound in the Basin are mainly methane and nitrogen. These biogases are characterized by high dry coefficients(C1/C1-5ratio)of 0.99, light carbon isotopes of methane(-65.57 %!-63.14 %）， especially heavy hydrogen isotopic values("Dc1%）of -172. 1 %!-108. 5 %. Geochemical data show that the Guaternary and Pliocene mud has the meanTOC value of 0.4 % and contains abundant organic matter which can be degraded by bacteria. The organic matter mainly consists of coarse-fi ber,semi-fiber and protein.Noticeably,it contains a high content of amino acid that is an inter mediate product during the f or mation process of biogas. This indicates that the mudstone in the Guaternary and Pliocene of the Basin is f avourable to biogas f or mation and is good biogas sourcerock.The data of modeling eXperi ment,combined with the gas measurement log and geotemperat ure gradient data of the basin,can be used to predict that the main stage of bio-gas generation is bet ween 35 C and 65 C and the death temperat ure of bio-gases is about 85 C(eCuivalent with the burial depth of around 1 900 min the Basin）.Finally，we suggest the generation-evolution model of marine biogas in the Yinggehai basin.
2002, 20(3): 477-504.
Abstract:
Compound-specific stable carbon isotope analysis of n-alkanes and isoprenoids were conductedf or crude oils from Well Lunnan 14, Lunnan oilfield, tarim basin, NW China. it can be seen that the crude oils from the 0rdovician and Carboniferous productive horizons shared the same organic matter inputs while the triassic crude oil had different sources of organic matter input. in addition,the carbon isotope composition of isoprenoi dsis isotopically heavier than that of n-alkanes with the same carbon number. it is presumed that the biosynthesis pathway and intramolecular distribution of 13C might theoretically account for the recognized relationship between n-alkanes and isoprenoids in terms of carbon isotope compositions.
Compound-specific stable carbon isotope analysis of n-alkanes and isoprenoids were conductedf or crude oils from Well Lunnan 14, Lunnan oilfield, tarim basin, NW China. it can be seen that the crude oils from the 0rdovician and Carboniferous productive horizons shared the same organic matter inputs while the triassic crude oil had different sources of organic matter input. in addition,the carbon isotope composition of isoprenoi dsis isotopically heavier than that of n-alkanes with the same carbon number. it is presumed that the biosynthesis pathway and intramolecular distribution of 13C might theoretically account for the recognized relationship between n-alkanes and isoprenoids in terms of carbon isotope compositions.
2002, 20(3): 488-492.
Abstract:
To aimdirectly at the practical situation that the oil in Tarim basin can be preserved at depth much greater than in other ones，the experiments of oil cracking in to gas under pressure as high as in Tarimbasin are designed and carried out in this paper. The characteristics and yield of products f or med by the pyrolysis experiments With different pressure indicate that the pressure do have manifest influence on the processes of oil to gas. The chemical kinetic models that are constructed and calibrated by the experimental data With high pressure suggest that the activation energy of light oil to gas is relatively higher than that of the normal oil. The Weight average activation energies of oil cracking to gas under the high- pressure experiments are much higher than that of relative low- pressure experiments. Therefore，repression of high pressure f or decomposition of oil to gas has been testified Cuantitatively and the essence that the light oil contain ed less heteroatoms is more difficult to be degraded to gas has been explained.
To aimdirectly at the practical situation that the oil in Tarim basin can be preserved at depth much greater than in other ones，the experiments of oil cracking in to gas under pressure as high as in Tarimbasin are designed and carried out in this paper. The characteristics and yield of products f or med by the pyrolysis experiments With different pressure indicate that the pressure do have manifest influence on the processes of oil to gas. The chemical kinetic models that are constructed and calibrated by the experimental data With high pressure suggest that the activation energy of light oil to gas is relatively higher than that of the normal oil. The Weight average activation energies of oil cracking to gas under the high- pressure experiments are much higher than that of relative low- pressure experiments. Therefore，repression of high pressure f or decomposition of oil to gas has been testified Cuantitatively and the essence that the light oil contain ed less heteroatoms is more difficult to be degraded to gas has been explained.
2002, 20(3): 499-504.
Abstract:
Laboratory simulation has elucidated that high pressure(800 ~1000 atm）at moderate temperatures(300~500℃）can accelerate the structural evolution of natural bitumen in carbonate rocks. Under high pressures，the natural bitumen becomes more compact and regular in its structures. So the reflectance values(Rb）of bitumen increase obviously,and its Rb values and structural parameters (carbon lamellar distance d002，size of crystal nucleus，layer number of aromatic cycle and aromaticity)exceed that in the real thermal evolution level evidently. Nevertheless，this kind of bitumen preserves the chemical composition and distribution(including biomarkers）for med in true ther mal maturity. this uniCue geochemical nature differs from that of any published bitumen types(e.g.,ther mally matured bitumen,etc.)，which can be used to distinguish thermo-compressively matured bitumen fromother kinds of bitumens.
Laboratory simulation has elucidated that high pressure(800 ~1000 atm）at moderate temperatures(300~500℃）can accelerate the structural evolution of natural bitumen in carbonate rocks. Under high pressures，the natural bitumen becomes more compact and regular in its structures. So the reflectance values(Rb）of bitumen increase obviously,and its Rb values and structural parameters (carbon lamellar distance d002，size of crystal nucleus，layer number of aromatic cycle and aromaticity)exceed that in the real thermal evolution level evidently. Nevertheless，this kind of bitumen preserves the chemical composition and distribution(including biomarkers）for med in true ther mal maturity. this uniCue geochemical nature differs from that of any published bitumen types(e.g.,ther mally matured bitumen,etc.)，which can be used to distinguish thermo-compressively matured bitumen fromother kinds of bitumens.
2002, 20(3): 510-514.
Abstract:
The pyrolysis on-line gas chromatographic method of rock simulation,developed by Langf ang Branch of Research institute of Petroleum Exploration and Development,is a novel laboratory techniCue used to simulate hydrocarbon formation,which employs the unconventional grain size(0.5 ~2mm）. The results detected from the novel method of pyrolysis rock chips show that (1)The pyrolysate yields of unit Cuality rock of different samples are similar to that of conventional hydrous closed-system， so the t wo methods are comparable.(2)Rock pyrolysis experiment can reflect the yields of gas generated fromits host rock in different evolution stage. (3)The novel method is more valid in the potential evaluation of gas generation compared to that of conventional organic carbon in different evolution stage.(4)Anumber of conventional samples can be tested in rock pyrolysis experiment for its economical and simple method and the analytical cycle is short, so it is an available and credi ble techniCue for the judgement of validity and the Cuantitative evaluation of source rock. This technique will play more important role in the evaluation of source rock during the exploration of petroleum.
The pyrolysis on-line gas chromatographic method of rock simulation,developed by Langf ang Branch of Research institute of Petroleum Exploration and Development,is a novel laboratory techniCue used to simulate hydrocarbon formation,which employs the unconventional grain size(0.5 ~2mm）. The results detected from the novel method of pyrolysis rock chips show that (1)The pyrolysate yields of unit Cuality rock of different samples are similar to that of conventional hydrous closed-system， so the t wo methods are comparable.(2)Rock pyrolysis experiment can reflect the yields of gas generated fromits host rock in different evolution stage. (3)The novel method is more valid in the potential evaluation of gas generation compared to that of conventional organic carbon in different evolution stage.(4)Anumber of conventional samples can be tested in rock pyrolysis experiment for its economical and simple method and the analytical cycle is short, so it is an available and credi ble techniCue for the judgement of validity and the Cuantitative evaluation of source rock. This technique will play more important role in the evaluation of source rock during the exploration of petroleum.
2002, 20(3): 519-523.
Abstract:
Methane hydrates are nonstoichiometric crystalline compounds. They are formed by Water molecules that are linked together With hydrogen bonds and f or ma three -dimensional structure With cavities. The cavities can be occupied by certain molecules of methane gases. One cavity can accommodate only one molecule. These molecules should not interfere With the hydrogen bonds among the Water molecules，and they should have molecular diameters that are smaller than the diameter of the cavity. Methane hydrates play an important role in the exploitation，transportation,and processing of natural gas. There is a risk of hydrate formation at all the stages of natural gas handling due to the operating conditions of pressure and temperature that favor hydrate formation. We mainly discussed the equilibrium conditions of methane hydrates in this paper. The three- phase(H- LW- V）equilibrium of the methane hydrate experiment system in aqueous solutions containing AlCl 3 Was experimentally measured at pressures ranging from 4. 040 to 8. 382 MPa and at temperatures between 272. 15 and 278. 15K using the isothermal pressure search method. The addition of AlCl 3 exhibited a stronger inhibition effect as that observed f or other electrolytes(KCl)With the same concentration and discussed the reason. An empirical exponential equation is proposed to Well correlate the measured data for aqueous solution. The computed values matched the experimental data obtained in this Work very Well. At last,the aqueous solutions containing AlCl3 is a better inhibitor for oil gas pipeline in the oil-gas industry.
Methane hydrates are nonstoichiometric crystalline compounds. They are formed by Water molecules that are linked together With hydrogen bonds and f or ma three -dimensional structure With cavities. The cavities can be occupied by certain molecules of methane gases. One cavity can accommodate only one molecule. These molecules should not interfere With the hydrogen bonds among the Water molecules，and they should have molecular diameters that are smaller than the diameter of the cavity. Methane hydrates play an important role in the exploitation，transportation,and processing of natural gas. There is a risk of hydrate formation at all the stages of natural gas handling due to the operating conditions of pressure and temperature that favor hydrate formation. We mainly discussed the equilibrium conditions of methane hydrates in this paper. The three- phase(H- LW- V）equilibrium of the methane hydrate experiment system in aqueous solutions containing AlCl 3 Was experimentally measured at pressures ranging from 4. 040 to 8. 382 MPa and at temperatures between 272. 15 and 278. 15K using the isothermal pressure search method. The addition of AlCl 3 exhibited a stronger inhibition effect as that observed f or other electrolytes(KCl)With the same concentration and discussed the reason. An empirical exponential equation is proposed to Well correlate the measured data for aqueous solution. The computed values matched the experimental data obtained in this Work very Well. At last,the aqueous solutions containing AlCl3 is a better inhibitor for oil gas pipeline in the oil-gas industry.
