Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the elec...Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the electrical properties of the polymer solution. Then, according to the different processes for polymer flooding the reservoir, we perform rock resistivity experiments and analyze the rock resistivity variations in different displacement phases. We also compare the resistivity log responses of oil layers filled with the polymer solution to those filled with water. The results show that when displacing the oil-bearing core by different polymers, the resistivity changes monotonously decrease and show either ＂W＂ type or ＂S＂ type. The resistivity log responses are weak when displacing water and there is no flooded show if the oil layer is injected by a fresh water polymer solution. If the oil layer is injected by a sewage polymer solution, the resistivity log response has similar characteristic as a polluted water flooded layer.展开更多
Pore brine potassium and deep sand gravel layer found is of large size and high economic value liquid potash deposit in western Qaidam basin depression tectonic(Fig.1).Because the reservoir is relatively thick,it is d...Pore brine potassium and deep sand gravel layer found is of large size and high economic value liquid potash deposit in western Qaidam basin depression tectonic(Fig.1).Because the reservoir is relatively thick,it is difficult to展开更多
The lithologies of the Chinese Continental Scientific Drilling main hole （CCSD-MH） are mainly comprised of orthogneiss,paragneiss,eclogite,amphibolite,and ultramafic rocks.The statistical results of logs of CCSD-MH ...The lithologies of the Chinese Continental Scientific Drilling main hole （CCSD-MH） are mainly comprised of orthogneiss,paragneiss,eclogite,amphibolite,and ultramafic rocks.The statistical results of logs of CCSD-MH indicate that ultramafic rocks are characterized by very high CNL （neutron log） and very low GR （gamma ray log） and RD （resistivity log）;eclogites are characterized by high DEN （density）,VP （P-wave velocity） and PE （photoelectric absorption capture cross section）;orthogneiss and paragneiss are characterized by high GR,U （uranium content）,Th （thorium content）,K （potassium content） and RD,and low DEN,PE,and CNL;logging values of amphibolite are between the logging values of eclogites and paragneiss.In addition,the logs could reflect the degree of retrograde metamorphism of eclogites.The upper section （100-2 000 m） shows higher DEN,PE,VP,and lower GR,U,Th,K,RD than the lower section （2 000-5 000 m）.Most logs of the upper section are more fluctuant than those of the lower section.This indicates that the upper section has more heterogeneities than the lower section.The cross plots of logs indicate that DEN,GR,K,and CNL are more powerful in identifying ultrahigh pressure metamorphic （UHPM） rocks at the CCSD-MH.GR value of the rocks from CCSD-MH shows obviously an increasing trend from ultramafic rock （the most mafic rocks at CCSD-MH） to orthogneiss （the most acid rocks at CCSD-MH）.On the contrary,DEN value decreases from the ultramafic rock to the orthogneiss.CNL log is a good indicator of the content of structure water in crystalline rocks.展开更多
Carbonate gas reservoir in the eastern area on the Right Bank of the Amu Darya River,Turkmenistan,are of low-porosity and with developed fractures.In this area,fractures control reservoir properties and natural gas pr...Carbonate gas reservoir in the eastern area on the Right Bank of the Amu Darya River,Turkmenistan,are of low-porosity and with developed fractures.In this area,fractures control reservoir properties and natural gas production,and karst fractures are the most important kind of fractures,so their identification and evaluation are quite necessary.In this paper,fracture types were identified and their occurrence was extracted by using conventional logging and image logging data after core calibration.Then,the distribution characteristics of karst fractures and their controlling effect on reservoirs were studied according to the identification results.And the following research results were obtained.First,karst fractures are mainly of high angle with the characteristic of mono system and the interactive relation of genesis.Second,they are mainly distributed in the upper XVhp layer of CallovianeOxford Stage and the lower XVa2eXVI layer.Third,they are the main effective fractures in this area.The dissolved pores are connected effectively through the expanded karst fractures by dissolution,and consequently reservoirs of high porosity and permeability are formed and they are the important reservoir type and high-yield gas reservoir in this area.Fourth,karst fractures are related to high-yield wells and high-yield layers in this area,and they also control the distribution of high-yield reservoirs in the lower part of CallovianeOxford Stage.It is concluded that by virtue of imaging logging and conventional logging data,karst fractures,unfilled fractures,semi-filled fractures and fullyfilled fractures can be identified and evaluated better.Furthermore,the identification and evaluation of karst fractures deepen the understanding on fractured reservoirs in this area,improve the reservoir evaluation effect,and provide the basis for the target horizon and azimuth optimization of horizontal wells and highly deviated wells.And it is also indicated that the reservoirs with developed karst fractures are the subsequent important drilling targets.展开更多
Multi-type unconventional gas-bearing reservoirs with different lithologies and gas accumulation potential occur in the deep part of the Songliao basin.However,the reservoirs are non-homogeneous,the gas components dif...Multi-type unconventional gas-bearing reservoirs with different lithologies and gas accumulation potential occur in the deep part of the Songliao basin.However,the reservoirs are non-homogeneous,the gas components differ substantially,and not all types of gas-bearing reservoirs have been identified or evaluated.The International Continental Scientific Drilling Program(ICDP)is used as an example to conduct qualitative and quantitative evaluations of deep multi-type unconventional gas-bearing reservoirs using conventional and specialized logging data.The core test data are used to determine the physical properties.The porosity and permeability are compared and analyzed using different methods and models.The results show that the reservoirs have low to ultra-low porosity and ultra-low permeability.Based on the comparison of the rock mechanical parameters and mineral composition,brittleness evaluation parameters are proposed for different types of deep reservoirs in the study region.The mineral brittleness index is highly consistent with the brittleness index based on rock mechanics.An identification method for deep multi-type gas-bearing reservoir and a classification approach for different gas properties are established based on the logging response and parameter interpretation.The methane gas reservoirs have low density(DEN)and low compensated neutron logging(CNL)values and high acoustic(AC)time difference and high resistivity(RT)values.The CO_(2)gas reservoirs have lower RT values and higher CNL values than the hydrocarbon gas reservoirs.The comprehensive analysis of deep gas source rock conditions and of the source-reservoir relationship provides insights for the evaluation of deep multi-type unconventional gas reservoirs.The discovery of high hydrogen content is of significant importance for developing new areas for deep natural gas exploration.展开更多
Compared with conventional gas reservoirs,shale gas reservoirs are not sensitive to petrophysical properties,making it much difficult to identify this kind of reservoirs with well logging technologies.Therefore,throug...Compared with conventional gas reservoirs,shale gas reservoirs are not sensitive to petrophysical properties,making it much difficult to identify this kind of reservoirs with well logging technologies.Therefore,through a comparison of the logging curves of the Lower Silurian Longmaxi marine shale in the Jiaoshiba area,Sichuan Basin,it is found that the mud shale on conventional log curves generally features high gamma ray,high uranium,low thorium,low kalium,relative high resistivity,high interval transit time,low neutron,low density and low photoelectric absorption cross section index,while on elements logging curves,it features an increase of silicon content and a decrease of aluminum and iron content.Based on the logging response characteristics of mud shale,the logging curves most sensitive to shale,gamma ray,neutron and density logging were selected and overlaid to identify mud shale effectively.On the basis of qualitative identification,the density logging value can identify the non-organic-rich mud shale from organic-rich mud shale,because the former has a density of 2.61–2.70 g/cm^(3),while the latter has a density of less than 2.61 g/cm^(3).The identification results agree well with the results of field gas content test,TOC experiment,and gas logging,so this study can provide reference for the logging interpretation.展开更多
The Anda Sag,the northern part of the Xujiaweizi Fault Depression in the Songliao Basin,contains high-quality source rocks and tight,lithologic gas deposit-dominated volcanic reservoirs of the Lower Cretaceous Yingche...The Anda Sag,the northern part of the Xujiaweizi Fault Depression in the Songliao Basin,contains high-quality source rocks and tight,lithologic gas deposit-dominated volcanic reservoirs of the Lower Cretaceous Yingcheng Formation.This area is known to have a variety of volcanic edifices that are characterized by multi-phase eruption and superimposed distribution.Currently,the sag has been highly explored,and drilling of targets in the critical crater areas with reservoirs relatively developed has basically finished.So,additional targets will be defined.Thus,a criterion for dividing the volcanic eruption phases was established based on core,well log and seismic response marks.Through a wellseismic skeleton section analysis,it was believed that three volcanic eruption phases(Ⅰ,Ⅱ and Ⅲ)occurred in the Anda Sag.Finally,the volcanic edifice and facies belt distribution of each phase were predicted by using seismic coherence body and trend-surface analysis technologies,with over 30 new volcanic crater targets identified.The predicted results show that the distribution of lithofacies and lithologies determines the framework of better volcanic reservoirs in the west and south than that in the east and north respectively.Lithological-structural gas reservoirs are dominant in the west,while tight lithologic gas reservoirs are dominant in the east.Based on the study results,the favorable exploration area is finalized as 950 km^(2),a potential of 100 billion m3 gas resources has been implemented.展开更多
This study pertains to the evaluation of shale gas and rock physics properties of this area with respect to its total organic content of Sember Formation, Khiproarea, Pakistan. We use well logs data for this study. Th...This study pertains to the evaluation of shale gas and rock physics properties of this area with respect to its total organic content of Sember Formation, Khiproarea, Pakistan. We use well logs data for this study. The Khipro area is prominent in the Lower Indus Basin for its hydrocarbon (oil and gas) structural traps. In shale gas evaluation, TOC of Sember Formation is estimated. The analysis has been done with the help of the wire line data of the well Bilal North-01. The presence of shale gas in the study area is analyzed with the help of different techniques. Rock physics and petrophysical analysis have been done in order to get the properties of the area related to the shale gas evaluation.展开更多
Identification of the favorable salt-and potash-forming layer,we still mainly rely on logging interpretation and coring verification.However,we both know that the continuously carbonate platform is cyclical growing.It...Identification of the favorable salt-and potash-forming layer,we still mainly rely on logging interpretation and coring verification.However,we both know that the continuously carbonate platform is cyclical growing.It has recorded valuable information about the phase transition of carbonate rocks,which were synchronized with the relative sea-level cycles.This paper presents a fast and展开更多
This paper studies the alluvial fan facies characteristics and distribution in the Lower Talang Acar Formation in the Northeast Betara Oilfield. The conglomerate sedimentary characteristics and its distribution were s...This paper studies the alluvial fan facies characteristics and distribution in the Lower Talang Acar Formation in the Northeast Betara Oilfield. The conglomerate sedimentary characteristics and its distribution were studied based on core data, logging interpretation and seismic property analysis. The research indicated that alluvial fan deposits of Bed F in the Lower Talang Akar Formation were characterized by coarse granularity, poor sorting and low quality. Sand-bodies accumulate longitudinally, and inter-layers are poorly developed, extending locally in the transverse orientation. Typical logging response of alluvial fan system is summarized, and conglomerate is characterized by low gamma-ray （GR） intensity, low resistance, high density and low value between DLD and LLD, which reflects poor physical reservoir properties, coarse rocks and relatively high density. Conglomerate is developed mainly in the northeast and middle-south of the studied area. The upper part of bed F is found in a small area in the middle-south, while the lower part of bed F is developed in a relatively large area in the middle-south.展开更多
基金sponsored by the Major National Oil&Gas Specific Project (Grant No.2011ZX05020 008)
文摘Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the electrical properties of the polymer solution. Then, according to the different processes for polymer flooding the reservoir, we perform rock resistivity experiments and analyze the rock resistivity variations in different displacement phases. We also compare the resistivity log responses of oil layers filled with the polymer solution to those filled with water. The results show that when displacing the oil-bearing core by different polymers, the resistivity changes monotonously decrease and show either ＂W＂ type or ＂S＂ type. The resistivity log responses are weak when displacing water and there is no flooded show if the oil layer is injected by a fresh water polymer solution. If the oil layer is injected by a sewage polymer solution, the resistivity log response has similar characteristic as a polluted water flooded layer.
文摘Pore brine potassium and deep sand gravel layer found is of large size and high economic value liquid potash deposit in western Qaidam basin depression tectonic(Fig.1).Because the reservoir is relatively thick,it is difficult to
基金supported by the Special Fund for Basic Scientific Research of Central Colleges (No. CUG090106)the National Basic Research Program of China (No. 2003CB716500)
文摘The lithologies of the Chinese Continental Scientific Drilling main hole （CCSD-MH） are mainly comprised of orthogneiss,paragneiss,eclogite,amphibolite,and ultramafic rocks.The statistical results of logs of CCSD-MH indicate that ultramafic rocks are characterized by very high CNL （neutron log） and very low GR （gamma ray log） and RD （resistivity log）;eclogites are characterized by high DEN （density）,VP （P-wave velocity） and PE （photoelectric absorption capture cross section）;orthogneiss and paragneiss are characterized by high GR,U （uranium content）,Th （thorium content）,K （potassium content） and RD,and low DEN,PE,and CNL;logging values of amphibolite are between the logging values of eclogites and paragneiss.In addition,the logs could reflect the degree of retrograde metamorphism of eclogites.The upper section （100-2 000 m） shows higher DEN,PE,VP,and lower GR,U,Th,K,RD than the lower section （2 000-5 000 m）.Most logs of the upper section are more fluctuant than those of the lower section.This indicates that the upper section has more heterogeneities than the lower section.The cross plots of logs indicate that DEN,GR,K,and CNL are more powerful in identifying ultrahigh pressure metamorphic （UHPM） rocks at the CCSD-MH.GR value of the rocks from CCSD-MH shows obviously an increasing trend from ultramafic rock （the most mafic rocks at CCSD-MH） to orthogneiss （the most acid rocks at CCSD-MH）.On the contrary,DEN value decreases from the ultramafic rock to the orthogneiss.CNL log is a good indicator of the content of structure water in crystalline rocks.
文摘Carbonate gas reservoir in the eastern area on the Right Bank of the Amu Darya River,Turkmenistan,are of low-porosity and with developed fractures.In this area,fractures control reservoir properties and natural gas production,and karst fractures are the most important kind of fractures,so their identification and evaluation are quite necessary.In this paper,fracture types were identified and their occurrence was extracted by using conventional logging and image logging data after core calibration.Then,the distribution characteristics of karst fractures and their controlling effect on reservoirs were studied according to the identification results.And the following research results were obtained.First,karst fractures are mainly of high angle with the characteristic of mono system and the interactive relation of genesis.Second,they are mainly distributed in the upper XVhp layer of CallovianeOxford Stage and the lower XVa2eXVI layer.Third,they are the main effective fractures in this area.The dissolved pores are connected effectively through the expanded karst fractures by dissolution,and consequently reservoirs of high porosity and permeability are formed and they are the important reservoir type and high-yield gas reservoir in this area.Fourth,karst fractures are related to high-yield wells and high-yield layers in this area,and they also control the distribution of high-yield reservoirs in the lower part of CallovianeOxford Stage.It is concluded that by virtue of imaging logging and conventional logging data,karst fractures,unfilled fractures,semi-filled fractures and fullyfilled fractures can be identified and evaluated better.Furthermore,the identification and evaluation of karst fractures deepen the understanding on fractured reservoirs in this area,improve the reservoir evaluation effect,and provide the basis for the target horizon and azimuth optimization of horizontal wells and highly deviated wells.And it is also indicated that the reservoirs with developed karst fractures are the subsequent important drilling targets.
基金supported by the National Natural Science Foundation of China(Grant Nos.42072168 and 41802156)the National Key R&D Program of China(Grant No.2019YFC0605405)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2022YQDC06)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(Grant No.PRP/open2006)。
文摘Multi-type unconventional gas-bearing reservoirs with different lithologies and gas accumulation potential occur in the deep part of the Songliao basin.However,the reservoirs are non-homogeneous,the gas components differ substantially,and not all types of gas-bearing reservoirs have been identified or evaluated.The International Continental Scientific Drilling Program(ICDP)is used as an example to conduct qualitative and quantitative evaluations of deep multi-type unconventional gas-bearing reservoirs using conventional and specialized logging data.The core test data are used to determine the physical properties.The porosity and permeability are compared and analyzed using different methods and models.The results show that the reservoirs have low to ultra-low porosity and ultra-low permeability.Based on the comparison of the rock mechanical parameters and mineral composition,brittleness evaluation parameters are proposed for different types of deep reservoirs in the study region.The mineral brittleness index is highly consistent with the brittleness index based on rock mechanics.An identification method for deep multi-type gas-bearing reservoir and a classification approach for different gas properties are established based on the logging response and parameter interpretation.The methane gas reservoirs have low density(DEN)and low compensated neutron logging(CNL)values and high acoustic(AC)time difference and high resistivity(RT)values.The CO_(2)gas reservoirs have lower RT values and higher CNL values than the hydrocarbon gas reservoirs.The comprehensive analysis of deep gas source rock conditions and of the source-reservoir relationship provides insights for the evaluation of deep multi-type unconventional gas reservoirs.The discovery of high hydrogen content is of significant importance for developing new areas for deep natural gas exploration.
基金National Science and Technology Major Project“Appraisal of shale gas resources and selection of play in Shangyangzi and Yunnan-Guizhou areas”(No.14B12XQ151001).
文摘Compared with conventional gas reservoirs,shale gas reservoirs are not sensitive to petrophysical properties,making it much difficult to identify this kind of reservoirs with well logging technologies.Therefore,through a comparison of the logging curves of the Lower Silurian Longmaxi marine shale in the Jiaoshiba area,Sichuan Basin,it is found that the mud shale on conventional log curves generally features high gamma ray,high uranium,low thorium,low kalium,relative high resistivity,high interval transit time,low neutron,low density and low photoelectric absorption cross section index,while on elements logging curves,it features an increase of silicon content and a decrease of aluminum and iron content.Based on the logging response characteristics of mud shale,the logging curves most sensitive to shale,gamma ray,neutron and density logging were selected and overlaid to identify mud shale effectively.On the basis of qualitative identification,the density logging value can identify the non-organic-rich mud shale from organic-rich mud shale,because the former has a density of 2.61–2.70 g/cm^(3),while the latter has a density of less than 2.61 g/cm^(3).The identification results agree well with the results of field gas content test,TOC experiment,and gas logging,so this study can provide reference for the logging interpretation.
文摘The Anda Sag,the northern part of the Xujiaweizi Fault Depression in the Songliao Basin,contains high-quality source rocks and tight,lithologic gas deposit-dominated volcanic reservoirs of the Lower Cretaceous Yingcheng Formation.This area is known to have a variety of volcanic edifices that are characterized by multi-phase eruption and superimposed distribution.Currently,the sag has been highly explored,and drilling of targets in the critical crater areas with reservoirs relatively developed has basically finished.So,additional targets will be defined.Thus,a criterion for dividing the volcanic eruption phases was established based on core,well log and seismic response marks.Through a wellseismic skeleton section analysis,it was believed that three volcanic eruption phases(Ⅰ,Ⅱ and Ⅲ)occurred in the Anda Sag.Finally,the volcanic edifice and facies belt distribution of each phase were predicted by using seismic coherence body and trend-surface analysis technologies,with over 30 new volcanic crater targets identified.The predicted results show that the distribution of lithofacies and lithologies determines the framework of better volcanic reservoirs in the west and south than that in the east and north respectively.Lithological-structural gas reservoirs are dominant in the west,while tight lithologic gas reservoirs are dominant in the east.Based on the study results,the favorable exploration area is finalized as 950 km^(2),a potential of 100 billion m3 gas resources has been implemented.
文摘This study pertains to the evaluation of shale gas and rock physics properties of this area with respect to its total organic content of Sember Formation, Khiproarea, Pakistan. We use well logs data for this study. The Khipro area is prominent in the Lower Indus Basin for its hydrocarbon (oil and gas) structural traps. In shale gas evaluation, TOC of Sember Formation is estimated. The analysis has been done with the help of the wire line data of the well Bilal North-01. The presence of shale gas in the study area is analyzed with the help of different techniques. Rock physics and petrophysical analysis have been done in order to get the properties of the area related to the shale gas evaluation.
文摘Identification of the favorable salt-and potash-forming layer,we still mainly rely on logging interpretation and coring verification.However,we both know that the continuously carbonate platform is cyclical growing.It has recorded valuable information about the phase transition of carbonate rocks,which were synchronized with the relative sea-level cycles.This paper presents a fast and
文摘This paper studies the alluvial fan facies characteristics and distribution in the Lower Talang Acar Formation in the Northeast Betara Oilfield. The conglomerate sedimentary characteristics and its distribution were studied based on core data, logging interpretation and seismic property analysis. The research indicated that alluvial fan deposits of Bed F in the Lower Talang Akar Formation were characterized by coarse granularity, poor sorting and low quality. Sand-bodies accumulate longitudinally, and inter-layers are poorly developed, extending locally in the transverse orientation. Typical logging response of alluvial fan system is summarized, and conglomerate is characterized by low gamma-ray （GR） intensity, low resistance, high density and low value between DLD and LLD, which reflects poor physical reservoir properties, coarse rocks and relatively high density. Conglomerate is developed mainly in the northeast and middle-south of the studied area. The upper part of bed F is found in a small area in the middle-south, while the lower part of bed F is developed in a relatively large area in the middle-south.
