To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of ...To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of porous reservoir prediction.Scattering imaging three-parameter wavelet transform technology was used to accurately predict small-scale cave bodies.The joint inversion method of velocity and amplitude anisotropy was developed to improve the accuracy of small and medium-sized fracture prediction.The results of multiscale fracture modeling and characterization,interwell connectivity analysis,and connection path prediction are consistent with the production condition.Finally,based on the above prediction findings,favorable reservoir development areas were predicted.The above ideas and strategies have great application value for the efficient exploration and development of complex storage space reservoirs and the optimization of high-yield well locations.展开更多
Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is diffic...Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner Ville distribution （SPWD） were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals.展开更多
In hydrocarbon reservoirs, seismic waveforms become complex and the correlation dimension becomes smaller. Seismic waves are signals with a definite frequency bandwidth and the waveform is affected by all the frequenc...In hydrocarbon reservoirs, seismic waveforms become complex and the correlation dimension becomes smaller. Seismic waves are signals with a definite frequency bandwidth and the waveform is affected by all the frequency components in the band. The results will not define the reservoir well if we calculate correlation dimension directly. In this paper, we present a method that integrates empirical mode decomposition （EMD） and correlation dimension. EMD is used to decompose the seismic waves and calculate the correlation dimension of every intrinsic mode function （IMF） component of the decomposed wave. Comparing the results with reservoirs identified by known wells, the most effective IMF is chosen and used to predict the reservoir. The method is applied in the Triassic Zhongyou group in the XX area of the Tahe oil field with quite good results.展开更多
The maximum effective hole-diameter mathematical modei describing the flow of slightly compressible fluid through a commingled reservoir was solved rigorously with consideration of wellbore storage and different skin ...The maximum effective hole-diameter mathematical modei describing the flow of slightly compressible fluid through a commingled reservoir was solved rigorously with consideration of wellbore storage and different skin factors. The exact solutions for wellbore pressure and the production rate obtained from layer j for a well production at a constant rate from a radial drainage area with infinite and constant pressure and no flow outer boundary condition were expressed in terms of ordinary Bessel functions. These solutions were computed numerically by the Crump's numerical inversion method and the behavior of systems was studied as a function of various reservoir parameters. The modei was compared with the real wellbore radii modei. The new modei is numerically stable when the skin factor is positive and negative, but the real wellbore radii modei is numerically stable only when the skin factor is positive.展开更多
The hydrocarbon detection techniques used currently are generally based on the theory of single-phase medium, but hydrocarbon reservoir mostly is multi-phase medium, therefore, multisolutions and uncertainties are exi...The hydrocarbon detection techniques used currently are generally based on the theory of single-phase medium, but hydrocarbon reservoir mostly is multi-phase medium, therefore, multisolutions and uncertainties are existed in the result of hydrocarbon detection. This paper presents a fast way to detect hydrocarbon in accordance with BOIT theory and laboratory data. The technique called DHAF technique has been applied to several survey area and obtained good result where the coincidence rate for hydrocarbon detection is higher than other similar techniques. The method shows a good prospect of the application in hydrocarbon detecting at exploration stage and in reservoir monitoring at production stage.展开更多
High-resolution exploration for lithologic targets confronted with difficulties due to the original brought out from geophysical and geologic characteristics of the loess hills and the very thick deserts in Ordos. Sci...High-resolution exploration for lithologic targets confronted with difficulties due to the original brought out from geophysical and geologic characteristics of the loess hills and the very thick deserts in Ordos. Scientific research since mid 1990s has conducted three acquisition techniques including the high-resolution crooked line survey in valleys, high-resolution multiple straight line survey and 3D survey, under different surface conditions and for different geological targets.展开更多
For thin gas reservoir of low-porosity and low-permeability in the loess desert area, a suite of lateral reservoir prediction techniques has been developed by Changqing Oil Company and the excellent effects achieved i...For thin gas reservoir of low-porosity and low-permeability in the loess desert area, a suite of lateral reservoir prediction techniques has been developed by Changqing Oil Company and the excellent effects achieved in exploration and exploitation in the areas such as Yulin, Wushenqi,Suligemiao, Shenmu etc., so that the Upper Paleozoic gas reserve has been stably increasing for eight years in Changqing Oilfield. The paper analyzed the effects and experience of the application of these techniques in detail.展开更多
Nowadays, it becomes very urgent to find remain oil under the oil shortage worldwide.However, most of simple reservoirs have been discovered and those undiscovered are mostly complex structural, stratigraphic and lith...Nowadays, it becomes very urgent to find remain oil under the oil shortage worldwide.However, most of simple reservoirs have been discovered and those undiscovered are mostly complex structural, stratigraphic and lithologic ones. Summarized in this paper is the integrated seismic processing/interpretation technique established on the basis of pre-stack AVO processing and interpretation.Information feedbacks occurred between the pre-stack and post-stack processes so as to improve the accuracy in utilization of data and avoid pitfalls in seismic attributes. Through the integration of seismic data with geologic data, parameters that were most essential to describing hydrocarbon characteristics were determined and comprehensively appraised, and regularities of reservoir generation and distribution were described so as to accurately appraise reservoirs, delineate favorite traps and pinpoint wells.展开更多
By the end of 2002, there are about 219 production wells (including 12 reinjection wells) in Tianjin. The annual production rate is 1.5×10 7 m 3 and the reinjection rate is 1.66×10 6 m 3. The main side effec...By the end of 2002, there are about 219 production wells (including 12 reinjection wells) in Tianjin. The annual production rate is 1.5×10 7 m 3 and the reinjection rate is 1.66×10 6 m 3. The main side effect anticipated from reinjection is the cooling of the reservoir. It is necessary to estimate the thermal breakthrough time in different distances between injection production wells. This paper describes the 2 D mass and heat transfer in the heterogeneous fractured rocks. The equations that arise for each grid block must be linearized. The main reinjection model is simulated by a program of the TOUGH2 to analyze the change of the temperature field and predict the pressure and heat break through. The tracer test is very important for understanding the transportation pathway and transport channel/space in the doublet system, and estimating the possible cooling resulted from the injection processes.展开更多
Limited by serious heterogeneity both horizontally and vertically, water driving of low-permeability layers in Qiaokou oilfield appears to be very difficult. As the classⅠ layer reaches the stage of high water-conten...Limited by serious heterogeneity both horizontally and vertically, water driving of low-permeability layers in Qiaokou oilfield appears to be very difficult. As the classⅠ layer reaches the stage of high water-content too early, the level of exploitation became worse with low-recovery. Regarding the serious heterogeneity and low recovery in layers class Ⅱand Ⅲ, composite fracturing technology suitable for this kind of reservoir was applied. Its basement was a lab study of indoor water driving efficiency and fracturing experiment. Perfect result has achieved by using the technology.展开更多
The Donghetang Formation (Upper Devonian) in central Tarim Basin has been thought an important oil and gas reservoir since the abundant oil and gas resources were found in the wells W16, W20, W34, and other fields. Ho...The Donghetang Formation (Upper Devonian) in central Tarim Basin has been thought an important oil and gas reservoir since the abundant oil and gas resources were found in the wells W16, W20, W34, and other fields. However, the sedimentary environment of the Donghetang Formation has been disputed because it suffered from both tidal and fluvial actions and there were not rich fossils in the sandstone. After the authors analyzed sedimentary features by means of drill cores, well logging data, paleosols, and with SEM obseruations, three kinds of sedimentary environments were distinguished: alluvial fan, tide-dominated estuary, and shelf. Particularly, the sedimentary features of tide-dominated estuary were studied in detail. Besides, the authors discussed sedimentary characteristics of the Donghetang Formation which was divided into two fourth-order sequences and five system tracts. At the same time, according to the forming process of five system tracts, the whole vertical evolution and lateral transition of tide-dominated estuary were illustrated clearly. Finally, the reservoir quality was evaluated based on porosity and permeability.展开更多
Frequency attenuation occurs when seismic waves propagate through the porous reservoirs containing hydrocarbons. Current researches on the seismic frequency attenuation mainly focus on the post-stack domain instead of...Frequency attenuation occurs when seismic waves propagate through the porous reservoirs containing hydrocarbons. Current researches on the seismic frequency attenuation mainly focus on the post-stack domain instead of the prestack domain. Here we propose the frequency attenuation gradient vs. offset （FAGVO） based on the amplitude variation with offset and frequency attenuation integral equations. We derive the FAGVO equation that equals to zero in a full-elastic medium and is negative in a viscoelastic medium. FAGVO is affected by the viscosity of the medium, the coefficients of reflection, the frequency variation, and high-frequency attenuation. FAGVO uses the differences of partially stacked data to decrease the interference caused by subsurface strata affecting the frequency attenuation, highlights the frequency attenuation gradient anomalies in hydrocarbon-bearing reservoir pores, and finally realizes the hydrocarbon fluid identification. The method was verified using a two-dimensional wave equation forward model and was found to be cost effective. Furthermore, the method does not require well information, which can be applied in the stage of seismic exploration, especially, in the exploration of a none-well project.展开更多
Methane-rich fluids were recognized to be hosted in the reservoir volcanic rocks as primary inclusions. Samples were collected from core-drillings of volcanic gas reservoirs with reversed δ13C of alkane in the Xujiaw...Methane-rich fluids were recognized to be hosted in the reservoir volcanic rocks as primary inclusions. Samples were collected from core-drillings of volcanic gas reservoirs with reversed δ13C of alkane in the Xujiaweizi depression of the Songliao Basin. The volcanic rocks are rhyolite dominant being enriched in the more incompatible elements like Cs, Rb, Ba, Th, U and Th with relative high LREE, depleted HREE and negative anomalies of Ti and Nb, suggesting a melt involving both in mantle source and crustal assimilation. Primary fluids hosted in the volcanic rocks should have the same provenance with the magma. The authors concluded that the enclosed CH4 in the volcanics are mantle/magma-derived alkane and the reversed δ13C of alkane in the corresponding gas reservoirs is partly resulted from mixture between biogenic and abiogenic gases.展开更多
文摘To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of porous reservoir prediction.Scattering imaging three-parameter wavelet transform technology was used to accurately predict small-scale cave bodies.The joint inversion method of velocity and amplitude anisotropy was developed to improve the accuracy of small and medium-sized fracture prediction.The results of multiscale fracture modeling and characterization,interwell connectivity analysis,and connection path prediction are consistent with the production condition.Finally,based on the above prediction findings,favorable reservoir development areas were predicted.The above ideas and strategies have great application value for the efficient exploration and development of complex storage space reservoirs and the optimization of high-yield well locations.
基金supported by National Natural Science Foundation of China(Grant No.40874059)
文摘Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner Ville distribution （SPWD） were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals.
基金sponsored by the National Nature Science Foundation of china(Grant No.40774064)National Hi-tech Research and Development Program of China(863 Program)(Grant No.2006AA0AA102-12)
文摘In hydrocarbon reservoirs, seismic waveforms become complex and the correlation dimension becomes smaller. Seismic waves are signals with a definite frequency bandwidth and the waveform is affected by all the frequency components in the band. The results will not define the reservoir well if we calculate correlation dimension directly. In this paper, we present a method that integrates empirical mode decomposition （EMD） and correlation dimension. EMD is used to decompose the seismic waves and calculate the correlation dimension of every intrinsic mode function （IMF） component of the decomposed wave. Comparing the results with reservoirs identified by known wells, the most effective IMF is chosen and used to predict the reservoir. The method is applied in the Triassic Zhongyou group in the XX area of the Tahe oil field with quite good results.
基金National Natural Science Foundation of China(No.50206016)Special Funds for Major State Basic Research Program of China(973 Program,No.1999022308)
文摘The maximum effective hole-diameter mathematical modei describing the flow of slightly compressible fluid through a commingled reservoir was solved rigorously with consideration of wellbore storage and different skin factors. The exact solutions for wellbore pressure and the production rate obtained from layer j for a well production at a constant rate from a radial drainage area with infinite and constant pressure and no flow outer boundary condition were expressed in terms of ordinary Bessel functions. These solutions were computed numerically by the Crump's numerical inversion method and the behavior of systems was studied as a function of various reservoir parameters. The modei was compared with the real wellbore radii modei. The new modei is numerically stable when the skin factor is positive and negative, but the real wellbore radii modei is numerically stable only when the skin factor is positive.
基金The project is sponsored by the Innovation Foundation of Key Lab of Geophysical Exploration under CNPC.
文摘The hydrocarbon detection techniques used currently are generally based on the theory of single-phase medium, but hydrocarbon reservoir mostly is multi-phase medium, therefore, multisolutions and uncertainties are existed in the result of hydrocarbon detection. This paper presents a fast way to detect hydrocarbon in accordance with BOIT theory and laboratory data. The technique called DHAF technique has been applied to several survey area and obtained good result where the coincidence rate for hydrocarbon detection is higher than other similar techniques. The method shows a good prospect of the application in hydrocarbon detecting at exploration stage and in reservoir monitoring at production stage.
文摘High-resolution exploration for lithologic targets confronted with difficulties due to the original brought out from geophysical and geologic characteristics of the loess hills and the very thick deserts in Ordos. Scientific research since mid 1990s has conducted three acquisition techniques including the high-resolution crooked line survey in valleys, high-resolution multiple straight line survey and 3D survey, under different surface conditions and for different geological targets.
文摘For thin gas reservoir of low-porosity and low-permeability in the loess desert area, a suite of lateral reservoir prediction techniques has been developed by Changqing Oil Company and the excellent effects achieved in exploration and exploitation in the areas such as Yulin, Wushenqi,Suligemiao, Shenmu etc., so that the Upper Paleozoic gas reserve has been stably increasing for eight years in Changqing Oilfield. The paper analyzed the effects and experience of the application of these techniques in detail.
文摘Nowadays, it becomes very urgent to find remain oil under the oil shortage worldwide.However, most of simple reservoirs have been discovered and those undiscovered are mostly complex structural, stratigraphic and lithologic ones. Summarized in this paper is the integrated seismic processing/interpretation technique established on the basis of pre-stack AVO processing and interpretation.Information feedbacks occurred between the pre-stack and post-stack processes so as to improve the accuracy in utilization of data and avoid pitfalls in seismic attributes. Through the integration of seismic data with geologic data, parameters that were most essential to describing hydrocarbon characteristics were determined and comprehensively appraised, and regularities of reservoir generation and distribution were described so as to accurately appraise reservoirs, delineate favorite traps and pinpoint wells.
文摘By the end of 2002, there are about 219 production wells (including 12 reinjection wells) in Tianjin. The annual production rate is 1.5×10 7 m 3 and the reinjection rate is 1.66×10 6 m 3. The main side effect anticipated from reinjection is the cooling of the reservoir. It is necessary to estimate the thermal breakthrough time in different distances between injection production wells. This paper describes the 2 D mass and heat transfer in the heterogeneous fractured rocks. The equations that arise for each grid block must be linearized. The main reinjection model is simulated by a program of the TOUGH2 to analyze the change of the temperature field and predict the pressure and heat break through. The tracer test is very important for understanding the transportation pathway and transport channel/space in the doublet system, and estimating the possible cooling resulted from the injection processes.
文摘Limited by serious heterogeneity both horizontally and vertically, water driving of low-permeability layers in Qiaokou oilfield appears to be very difficult. As the classⅠ layer reaches the stage of high water-content too early, the level of exploitation became worse with low-recovery. Regarding the serious heterogeneity and low recovery in layers class Ⅱand Ⅲ, composite fracturing technology suitable for this kind of reservoir was applied. Its basement was a lab study of indoor water driving efficiency and fracturing experiment. Perfect result has achieved by using the technology.
文摘The Donghetang Formation (Upper Devonian) in central Tarim Basin has been thought an important oil and gas reservoir since the abundant oil and gas resources were found in the wells W16, W20, W34, and other fields. However, the sedimentary environment of the Donghetang Formation has been disputed because it suffered from both tidal and fluvial actions and there were not rich fossils in the sandstone. After the authors analyzed sedimentary features by means of drill cores, well logging data, paleosols, and with SEM obseruations, three kinds of sedimentary environments were distinguished: alluvial fan, tide-dominated estuary, and shelf. Particularly, the sedimentary features of tide-dominated estuary were studied in detail. Besides, the authors discussed sedimentary characteristics of the Donghetang Formation which was divided into two fourth-order sequences and five system tracts. At the same time, according to the forming process of five system tracts, the whole vertical evolution and lateral transition of tide-dominated estuary were illustrated clearly. Finally, the reservoir quality was evaluated based on porosity and permeability.
基金supported by the Major National Science&Technology Project(No.2016ZX05003-003)the National High Technology Research and Development Program of China(863 Program)(No.2013AA064201)
文摘Frequency attenuation occurs when seismic waves propagate through the porous reservoirs containing hydrocarbons. Current researches on the seismic frequency attenuation mainly focus on the post-stack domain instead of the prestack domain. Here we propose the frequency attenuation gradient vs. offset （FAGVO） based on the amplitude variation with offset and frequency attenuation integral equations. We derive the FAGVO equation that equals to zero in a full-elastic medium and is negative in a viscoelastic medium. FAGVO is affected by the viscosity of the medium, the coefficients of reflection, the frequency variation, and high-frequency attenuation. FAGVO uses the differences of partially stacked data to decrease the interference caused by subsurface strata affecting the frequency attenuation, highlights the frequency attenuation gradient anomalies in hydrocarbon-bearing reservoir pores, and finally realizes the hydrocarbon fluid identification. The method was verified using a two-dimensional wave equation forward model and was found to be cost effective. Furthermore, the method does not require well information, which can be applied in the stage of seismic exploration, especially, in the exploration of a none-well project.
基金Supported by NSFC project No. 40372066 and SRFDP No. 20030183042
文摘Methane-rich fluids were recognized to be hosted in the reservoir volcanic rocks as primary inclusions. Samples were collected from core-drillings of volcanic gas reservoirs with reversed δ13C of alkane in the Xujiaweizi depression of the Songliao Basin. The volcanic rocks are rhyolite dominant being enriched in the more incompatible elements like Cs, Rb, Ba, Th, U and Th with relative high LREE, depleted HREE and negative anomalies of Ti and Nb, suggesting a melt involving both in mantle source and crustal assimilation. Primary fluids hosted in the volcanic rocks should have the same provenance with the magma. The authors concluded that the enclosed CH4 in the volcanics are mantle/magma-derived alkane and the reversed δ13C of alkane in the corresponding gas reservoirs is partly resulted from mixture between biogenic and abiogenic gases.
