HR: 11:45h
AN: U42A-06    [Abstracts]
TI: Acoustic Anisotropy Measurement and Interpretation in Deviated Wells
AU: Tang, X
EM: Xiaoming.Tang@bakerhughes.com
AF: HTC, Baker Hughes, Inc., 2001 Rankin Road, Houston, TX 77073 United States
AU: * Patterson, D
EM: Douglas.Patterson@bakerhughes.com
AF: HTC, Baker Hughes, Inc., 2001 Rankin Road, Houston, TX 77073 United States
AB: A current trend in petroleum exploration and production is that more and more deviated/horizontal wells are drilled, especially in deep water reservoirs like Gulf of Mexico. The issue of anisotropy is particularly important for deviated wells penetrating the soft sedimentary rocks of the reservoirs. In sedimentary formations, shales can be highly anisotropic due to mineral alignment, and sands can also be anisotropic due to their sensitivity to formation stresses. Many acoustic anisotropy measurements using cross-dipole tools have been made in deviated wells. However, interpreting the acoustic anisotropy data can be quite complicated, especially in the presence of strong anisotropy. In a deviated well, the well trajectory is neither perpendicular to, nor parallel with, the formation bedding planes. Consequently, the measured anisotropy is not the true formation anisotropy, but an apparent anisotropy at a given well deviation. Besides, several anisotropy parameters (e.g., Thomsen parameters) are needed to characterize the formation anisotropy while the cross-dipole measures only one of them. Nevertheless, the variation of the anisotropy and its associated azimuth relative to the well trajectory contains the information about the anisotropy parameters. By analyzing the anisotropy data in conjunction with the well configuration, we can characterize the relationship among the anisotropy parameters. By combining the data with lithology, we can also distinguish stress-induced anisotropy from other sources of anisotropy. The result is an improved characterization of formation anisotropy and its geological environment.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 5102 Acoustic properties
DE: 5194 Instruments and techniques
DE: 7260 Theory and modeling
DE: 7294 Instruments and techniques
SC: Union [U]
MN: 2005 Joint Assembly