The recently developed borehole dipole shear wave(S-wave)reflection imaging technique has been successfully applied to deep hydrocarbon exploration,allowing for accurate detection of fracture-cavity reservoirs tens of...The recently developed borehole dipole shear wave(S-wave)reflection imaging technique has been successfully applied to deep hydrocarbon exploration,allowing for accurate detection of fracture-cavity reservoirs tens of meters away from the borehole.Further developments in this technology needs to resolve the azimuthal 180°-ambiguity caused by the symmetry of the dipole sources and receivers,known as the“180°-ambiguity problem”in the well logging community.This paper aims to determine the azimuth of reflectors outside a borehole uniquely,which is crucial for optimizing deep hydrocarbon exploration and critical field operations(such as directional drilling).Based on the theory of interaction between elastic waves and reflectors outside the borehole,this paper analyzes the azimuthal response characteristics of reflected waves received in the borehole.We propose a new full-azimuthal dipole measurement mode to eliminate the azimuthal ambiguity through a multi-azimuth data reception and combination method.The method has been validated in laboratory azimuthal model test wells.Theoretical and experimental results indicate that the new measurement method preserves the azimuthal amplitude variation characteristic of the conventional four-component(4C)measurement and possesses a 360°periodicity for the wave phase variation,which can be effectively used to resolve the azimuthal 180°-ambiguity of the dipole shear reflection imaging.Based on the new method,a new full-azimuthal dipole shear reflection imaging tool prototype has been developed and field tested in a horizontal development well in the Tarim oil field.The acoustic reflection imaging results clearly demonstrate that the horizontal well crosses an approximately 30 m thick fault-karst body,with the imaging range outside the borehole extending up to 65 m.By analyzing the amplitude and phase shift of the acoustic reflection data,allowing for delineating the fault-karst body in the formation.This research provides both theoretical and experimental foundations for the development and application of borehole azimuthal acoustic reflection imaging technology for deep hydrocarbon exploration.展开更多
Slip boundary condition is commonly utilized to model elastic wave propagation through layered earth media. The same approach is used here to characterize acoustic wave propagation along a cased borehole with various ...Slip boundary condition is commonly utilized to model elastic wave propagation through layered earth media. The same approach is used here to characterize acoustic wave propagation along a cased borehole with various cement bond conditions. By modeling the cement layer between casing and formation as a viscoelastic slip interface with complex coupling rigidity parameters, one can not only reduce the complexity in the classical elastic wave modeling of the problem, but also efficiently model various complicated wave phenomena that are difficult for the existing modeling. More specifically, the new theory can well describe the effect of the cement bond condition change and the location of the change(i.e., whether it is in the first interface between casing and cement, or the second interface between cement and formation) on the acoustic waves,demonstrating the good modeling capability and predicting power. Application of the theory to field data shows that the theory can correctly model the acoustic wave characteristics and interpret the cement bond condition, thus providing a useful fundament theory for casing bond evaluation using acoustic logging.展开更多
基金supported jointly by the National Natural Science Foundation of China(Grant Nos.U21B2064 and 42174145)the Natural Science Foundation of Shandong Province(Grant No.ZR2024YQ062)+1 种基金the Laoshan National Laboratory Science and Technology Innovation Project(Grant No.LSKJ202203407)the Major Scientific and Technological Projects of China National Petroleum Corporation(Grant No.ZD2019-183-004)。
文摘The recently developed borehole dipole shear wave(S-wave)reflection imaging technique has been successfully applied to deep hydrocarbon exploration,allowing for accurate detection of fracture-cavity reservoirs tens of meters away from the borehole.Further developments in this technology needs to resolve the azimuthal 180°-ambiguity caused by the symmetry of the dipole sources and receivers,known as the“180°-ambiguity problem”in the well logging community.This paper aims to determine the azimuth of reflectors outside a borehole uniquely,which is crucial for optimizing deep hydrocarbon exploration and critical field operations(such as directional drilling).Based on the theory of interaction between elastic waves and reflectors outside the borehole,this paper analyzes the azimuthal response characteristics of reflected waves received in the borehole.We propose a new full-azimuthal dipole measurement mode to eliminate the azimuthal ambiguity through a multi-azimuth data reception and combination method.The method has been validated in laboratory azimuthal model test wells.Theoretical and experimental results indicate that the new measurement method preserves the azimuthal amplitude variation characteristic of the conventional four-component(4C)measurement and possesses a 360°periodicity for the wave phase variation,which can be effectively used to resolve the azimuthal 180°-ambiguity of the dipole shear reflection imaging.Based on the new method,a new full-azimuthal dipole shear reflection imaging tool prototype has been developed and field tested in a horizontal development well in the Tarim oil field.The acoustic reflection imaging results clearly demonstrate that the horizontal well crosses an approximately 30 m thick fault-karst body,with the imaging range outside the borehole extending up to 65 m.By analyzing the amplitude and phase shift of the acoustic reflection data,allowing for delineating the fault-karst body in the formation.This research provides both theoretical and experimental foundations for the development and application of borehole azimuthal acoustic reflection imaging technology for deep hydrocarbon exploration.
基金supported by the National Natural Science Foundation of China (Grant No. 41774141)
文摘Slip boundary condition is commonly utilized to model elastic wave propagation through layered earth media. The same approach is used here to characterize acoustic wave propagation along a cased borehole with various cement bond conditions. By modeling the cement layer between casing and formation as a viscoelastic slip interface with complex coupling rigidity parameters, one can not only reduce the complexity in the classical elastic wave modeling of the problem, but also efficiently model various complicated wave phenomena that are difficult for the existing modeling. More specifically, the new theory can well describe the effect of the cement bond condition change and the location of the change(i.e., whether it is in the first interface between casing and cement, or the second interface between cement and formation) on the acoustic waves,demonstrating the good modeling capability and predicting power. Application of the theory to field data shows that the theory can correctly model the acoustic wave characteristics and interpret the cement bond condition, thus providing a useful fundament theory for casing bond evaluation using acoustic logging.
