This paper discusses the principles of geologic constraints on reservoir stochastic modeling. By using the system science theory, two kinds of uncertainties, including random uncertainty and fuzzy uncertainty, are rec...This paper discusses the principles of geologic constraints on reservoir stochastic modeling. By using the system science theory, two kinds of uncertainties, including random uncertainty and fuzzy uncertainty, are recognized. In order to improve the precision of stochastic modeling and reduce the uncertainty in realization, the fuzzy uncertainty should be stressed, and the ＂geological genesis-controlled modeling＂ is conducted under the guidance of a quantitative geological pattern. An example of the Pingqiao horizontal-well division of the Ansai Oilfield in the Ordos Basin is taken to expound the method of stochastic modeling.展开更多
This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are re...This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load-displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.展开更多
With the aim of identifying novel thermostable esterases, comprehensive sequence databases and cloned fosmid libraries of metagenomes derived from an offshore oil reservoir on the Norwegian Continental Shelf were scre...With the aim of identifying novel thermostable esterases, comprehensive sequence databases and cloned fosmid libraries of metagenomes derived from an offshore oil reservoir on the Norwegian Continental Shelf were screened for enzyme candidates using both sequence-and function-based screening. From several candidates identified in both approaches, one enzyme discovered by the functional approach was verified as a novel esterase and subjected to a deeper characterization. The enzyme was successfully over-produced in Escherichia coli and was shown to be thermostable up to 90°C, with the highest esterase activity on short-chain ester substrates and with tolerance to solvents and metal ions. The fact that the thermostable enzyme was solely found by functional screening of the oil reservoir metagenomes illustrates the importance of this approach as a complement to purely sequence-based screening, in which the enzyme candidate was not detected. In addition, this example indicates the large potential of deep-sub-surface oil reservoir metagenomes as a source of novel, thermostable enzymes of potential relevance for industrial applications.展开更多
The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the midMesozoic,yet has experienced episodic phases of deformation since that time.In this paper,we document field evidence to c...The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the midMesozoic,yet has experienced episodic phases of deformation since that time.In this paper,we document field evidence to characterize and date the intra-plate tectonic history of the Gobi Altai region from the Triassic to the present.To this end,we provide detailed mapping of the structure and stratigraphy of the eastern flanks of Mt.Ih Bogd that contains the widest variety of rock-time units in the area.We carry out geochronological analysis of basaltic lavas and basement granite in the area.We demonstrate that a crystalline basement with a 502 ± 8 Ma granitoid（U/Pb） underwent two phases of basin formation in the Mesozoic.which we date with new40Ar/39Ar lava ages of 218.5 ± 1.5,123.2 ± 0.7 and 124.8 ± 1.2 Ma,respectively.Both phases are linked to deposition of fluvio-lacustrine sediments and trap-like basaltic volcanics,with cumulative thicknesses of 1000-1500 m.Both basins were likely north-facing half-grabens that developed underN-S extension,but were subsequently overthrusted by Paleozoic and older crystalline basement during a less well constrained,but likely mid-Cretaceous phase of N-S shortening and basin inversion.Our results are consistent with recent seismic imaging of rift basins100 km to the NE of the study area where a similar history was reconstructed.The multiple phases of intra-plate deformation appear to have parallel structural trends,most likely due to reactivated Paleozoic basement structures created during the original terrane amalgamation of the Central Asian Orogenic Belt continental crust.This strong basement heterogeneity may predispose it to reactivation,and make it sensitive to changes in the overall stress field of the Eurasian plate driven by forces at its margins and base.Detailed study of Mongolia’s multi-stage tectonic history may thus provide a key proxy for the long-term dynamics of the Eurasian plate.In addition,the repeated reactivation of the Gobi Altai region during the last 200 My supports the contention that non-cratonized continental interior regions composed of Phanerozoic terrane collages are particularly susceptible to fault reactivation,much more than older cratonized continental crust.展开更多
We study the 2-parameter acoustic Born series for an actual medium with constant velocity and a density distribution.Using a homogeneous background we define a perturbation,the difference between actual and reference ...We study the 2-parameter acoustic Born series for an actual medium with constant velocity and a density distribution.Using a homogeneous background we define a perturbation,the difference between actual and reference medium(we use background and reference as synonyms),which exhibits an anisotropic behavior due to the density distribution.For an actual medium with a constant velocity,the reference velocity can be selected so that the waves in the actual medium travel with the same speed as the waves in the background medium.Scattering theory decomposes the actual wave field into an infinite series where each term contains the perturbation and the propagators in the background medium.Hence,in this formalism,all propagations occur in the background medium and the actual medium is included only through the perturbations which scatter the propagating waves.The density-only perturbation has an isotropic and an anisotropic component.The anisotropic component is dependent on the incident direction of the propagating waves and behaves as a purposeful perturbation in the sense that it annihilates the part of the Born series that acts to correct the time to build the actual wave field,an unnecessary activity when the reference velocity is equal to the one in the actual medium.This means that the forward series is not attempting to correct for an issue that does not exist.We define the purposeful perturbation concept as the intrinsic knowledge of preciselywhat a given term is designed to accomplish.This is a remarkable behavior for a formalism that predicts the scatteredwave fieldwith an infinite series.At each order of approximation the output of the series is consistent with the fact that the time is correct because the velocity is always constant.In the density-only perturbation,the forward series only seeks to predict the correct amplitudes.Finally,we extend the analysis to a wave propagating in a medium where both density and velocity change.By selecting a convenient set of parameters,we find a conceptual framework for the multiparameter Born series.This framework provides an insightful analysis that can be mapped and applied to the concepts and algorithms of the inverse scattering series.展开更多
文摘This paper discusses the principles of geologic constraints on reservoir stochastic modeling. By using the system science theory, two kinds of uncertainties, including random uncertainty and fuzzy uncertainty, are recognized. In order to improve the precision of stochastic modeling and reduce the uncertainty in realization, the fuzzy uncertainty should be stressed, and the ＂geological genesis-controlled modeling＂ is conducted under the guidance of a quantitative geological pattern. An example of the Pingqiao horizontal-well division of the Ansai Oilfield in the Ordos Basin is taken to expound the method of stochastic modeling.
文摘This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load-displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.
文摘With the aim of identifying novel thermostable esterases, comprehensive sequence databases and cloned fosmid libraries of metagenomes derived from an offshore oil reservoir on the Norwegian Continental Shelf were screened for enzyme candidates using both sequence-and function-based screening. From several candidates identified in both approaches, one enzyme discovered by the functional approach was verified as a novel esterase and subjected to a deeper characterization. The enzyme was successfully over-produced in Escherichia coli and was shown to be thermostable up to 90°C, with the highest esterase activity on short-chain ester substrates and with tolerance to solvents and metal ions. The fact that the thermostable enzyme was solely found by functional screening of the oil reservoir metagenomes illustrates the importance of this approach as a complement to purely sequence-based screening, in which the enzyme candidate was not detected. In addition, this example indicates the large potential of deep-sub-surface oil reservoir metagenomes as a source of novel, thermostable enzymes of potential relevance for industrial applications.
基金UK NERC Grant NER/D/S/2003/00671 to WDCThe 2005 fieldwork of DJJvH was partly supported by an E.J.Garwood Grant of the Geological Society of London+1 种基金GBS was supported by the Molengraaff Foundation and the KF Hein FoundationDJJvH acknowledges funding through ERC Starting Grant 306810(SINK)and an NWO VIDI grant
文摘The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the midMesozoic,yet has experienced episodic phases of deformation since that time.In this paper,we document field evidence to characterize and date the intra-plate tectonic history of the Gobi Altai region from the Triassic to the present.To this end,we provide detailed mapping of the structure and stratigraphy of the eastern flanks of Mt.Ih Bogd that contains the widest variety of rock-time units in the area.We carry out geochronological analysis of basaltic lavas and basement granite in the area.We demonstrate that a crystalline basement with a 502 ± 8 Ma granitoid（U/Pb） underwent two phases of basin formation in the Mesozoic.which we date with new40Ar/39Ar lava ages of 218.5 ± 1.5,123.2 ± 0.7 and 124.8 ± 1.2 Ma,respectively.Both phases are linked to deposition of fluvio-lacustrine sediments and trap-like basaltic volcanics,with cumulative thicknesses of 1000-1500 m.Both basins were likely north-facing half-grabens that developed underN-S extension,but were subsequently overthrusted by Paleozoic and older crystalline basement during a less well constrained,but likely mid-Cretaceous phase of N-S shortening and basin inversion.Our results are consistent with recent seismic imaging of rift basins100 km to the NE of the study area where a similar history was reconstructed.The multiple phases of intra-plate deformation appear to have parallel structural trends,most likely due to reactivated Paleozoic basement structures created during the original terrane amalgamation of the Central Asian Orogenic Belt continental crust.This strong basement heterogeneity may predispose it to reactivation,and make it sensitive to changes in the overall stress field of the Eurasian plate driven by forces at its margins and base.Detailed study of Mongolia’s multi-stage tectonic history may thus provide a key proxy for the long-term dynamics of the Eurasian plate.In addition,the repeated reactivation of the Gobi Altai region during the last 200 My supports the contention that non-cratonized continental interior regions composed of Phanerozoic terrane collages are particularly susceptible to fault reactivation,much more than older cratonized continental crust.
文摘We study the 2-parameter acoustic Born series for an actual medium with constant velocity and a density distribution.Using a homogeneous background we define a perturbation,the difference between actual and reference medium(we use background and reference as synonyms),which exhibits an anisotropic behavior due to the density distribution.For an actual medium with a constant velocity,the reference velocity can be selected so that the waves in the actual medium travel with the same speed as the waves in the background medium.Scattering theory decomposes the actual wave field into an infinite series where each term contains the perturbation and the propagators in the background medium.Hence,in this formalism,all propagations occur in the background medium and the actual medium is included only through the perturbations which scatter the propagating waves.The density-only perturbation has an isotropic and an anisotropic component.The anisotropic component is dependent on the incident direction of the propagating waves and behaves as a purposeful perturbation in the sense that it annihilates the part of the Born series that acts to correct the time to build the actual wave field,an unnecessary activity when the reference velocity is equal to the one in the actual medium.This means that the forward series is not attempting to correct for an issue that does not exist.We define the purposeful perturbation concept as the intrinsic knowledge of preciselywhat a given term is designed to accomplish.This is a remarkable behavior for a formalism that predicts the scatteredwave fieldwith an infinite series.At each order of approximation the output of the series is consistent with the fact that the time is correct because the velocity is always constant.In the density-only perturbation,the forward series only seeks to predict the correct amplitudes.Finally,we extend the analysis to a wave propagating in a medium where both density and velocity change.By selecting a convenient set of parameters,we find a conceptual framework for the multiparameter Born series.This framework provides an insightful analysis that can be mapped and applied to the concepts and algorithms of the inverse scattering series.
