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The detection depth of current borehole acoustic reflection imaging is only tens of meters without high resolution. This considerably limits its wide application in the identification and fine description of unconventional reservoirs and in the optimization of drilling trajectories. Increasing the directional energy from the transmitter to a geological structure is an excellent way to solve this issue. In this study, a plasma source with a parabolic reflector was introduced during borehole acoustic reflection imaging. First, an experimental system was built for testing the plasma source. Next, the acoustic-electrical characteristics and directional radiation of the source were studied using experiments and a numerical simulation. Finally, the advantages, disadvantages, and feasibility of the plasma-transmitting source were analyzed; some suggestions for further work on the source and its logging application were proposed. The experimental and simulation results show that the use of a plasma source with a parabolic reflector can increase the detection depth of borehole acoustic reflection imaging to hundreds of meters with high resolution. This is crucial in imaging the geological structures near boreholes and enhancing oil-gas exploration and development.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9610984 | PMC |
http://dx.doi.org/10.3390/s22208050 | DOI Listing |
J Acoust Soc Am
July 2025
State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
In acoustic logging, the dipole-mode wave is a type of guided wave that propagates along the borehole, and its dispersion characteristics are typically used to invert the shear-wave velocity of the formation around the borehole. However, traditional dispersion-based inversions rely on the layered model assumption, limiting their applicability to formations that are either uniformly distributed along the borehole axis or exhibit gradual variations. As a method that directly fits observed waveforms, full waveform inversion (FWI) can be applied to various formation models without being constrained by the assumption of two-dimensional homogeneity.
View Article and Find Full Text PDFSci Rep
July 2025
Liaohe Geophysical Exploration Branch of BGP, CNPC, Panjin, 124010, China.
A borehole sidewall acoustic transmitter, specifically designed for openhole, introduces a unique approach to acoustic single-well reflection imaging logging, featuring transducers that directly contact the borehole's sidewall, much like the SBT tool employed in cased hole applications. Utilizing a three-dimensional finite-difference algorithm, the study conducts a numerical simulation of acoustic reflection imaging logging with the transmitter, successfully acquiring acoustic field data from both the borehole and the surrounding rock formation. Analysis of the acoustic field in rock formation shows that the radiation characteristics of the transmitter in two different work modes resemble those of tubular monopole and cross-dipole sources, respectively.
View Article and Find Full Text PDFSci Rep
July 2025
State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, Beijing, 102211, China.
The integrity of the roadway surrounding rock is directly related to the safety and stability of the mine, and it is of great significance to carry out a rapid evaluation method for the surrounding rock integrity of the coal mine roadway during the construction process. In response to the limitation of traditional borehole rock integrity evaluation methods on borehole wall images, this paper proposes a coal mine roadway rock integrity evaluation method based on borehole image-acoustic-radar data, utilizing the unique advantages of borehole image, acoustic scanning, and radar detection technologies in-situ. Firstly, by constructing a multivariate characteristic parameter analysis method for borehole rock mass structure, the multivariate characteristic parameter description of borehole rock mass structure can be achieved.
View Article and Find Full Text PDFACS Omega
June 2025
College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China.
Pore pressure stands as a foundation parameter for an optimal mud density window evaluation; thus, its accurate prediction plays an essential role in the success and safety of the well-drilling process. However, its prediction in complex geological formations remains one of the challenges, particularly in tectonic setting areas in which various complex geoprocess mechanisms drive the formation pressure system. Fracture structure, strong burial change, and strong formation heterogeneity of the Upper Wuerhe formation in the Jinlong 2 block form unique geological characteristics that impair the accuracy of parametric conventional prediction models.
View Article and Find Full Text PDFSensors (Basel)
March 2025
College of Petroleum Engineering, Xi'an Shiyou University, Xi'an 710065, China.
Traditional emitters used for downhole acoustic detection have limited radiation frequency and energy, making it difficult to transmit high-precision acoustic signals over long distances. This paper presents a plasma emitter in which high-pressure discharge generates a powerful spherical impulse wave with a wide frequency range. First, the discharge characteristics of the plasma needle-plate emitter are analyzed using high-voltage discharge experiments and discharge simulation models for underwater emitters.
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