Advanced Search
DSpace@MIT

Asymmetric source acoustic LWD for the improved formation shear velocity estimation

Research and Teaching Output of the MIT Community

Show simple item record

dc.contributor.author Chen, Tianrun
dc.contributor.author Wang, Bing
dc.contributor.author Zhu, Zhenya
dc.contributor.author Burns, Daniel R.
dc.contributor.other Massachusetts Institute of Technology. Earth Resources Laboratory en_US
dc.date.accessioned 2012-01-12T19:02:34Z
dc.date.available 2012-01-12T19:02:34Z
dc.date.issued 2009
dc.identifier.uri http://hdl.handle.net/1721.1/68333
dc.description.abstract Most acoustic LWD tools generate a single pure borehole mode (e.g., dipole or quadrupole) to estimate the formation shear velocity. We propose an approach where many borehole modes are generated and all the modes are used simultaneously to obtain a better shear estimate. In this approach we find the best fit to the dispersion characteristics of a number of modes, rather than one mode. We propose using an asymmetric source, that is a single source on one side of the tool, together with arrays of receivers distributed azimuthally around the tool to allow different modes to be identified and analyzed. We investigate such an approach using synthetic and laboratory data. The lab data uses a scale-model LWD tool with one active sources transducer mounted on the side of the tool. This source geometry generates monopole, dipole, and quadrupole modes simultaneously. Four sets of receiver arrays, each separated by 90 degrees azimuthally, are used to isolate and analyze each of these modes by adding and subtracting the signals received from different arrays. Based on the dispersion analysis and the method of least square fitting, we find that the by simultaneously using both dipole and quadrupole modes, we can reduce the residual error of the best fit shear velocity. It should be noted that higher order modes (e.g., hexapole, etc) will also be generated by an asymmetric source, and these modes could also be utilized with the appropriate azimuthal receiver configuration. en_US
dc.publisher Massachusetts Institute of Technology. Earth Resources Laboratory en_US
dc.relation.ispartofseries Earth Resources Laboratory Industry Consortia Annual Report;2009-03
dc.title Asymmetric source acoustic LWD for the improved formation shear velocity estimation en_US
dc.type Technical Report en_US
dc.contributor.mitauthor Chen, Tianrun
dc.contributor.mitauthor Wang, Bing
dc.contributor.mitauthor Zhu, Zhenya
dc.contributor.mitauthor Burns, Daniel R.
dspace.orderedauthors Chen, Tianrun; Wang, Bing; Zhu, Zhenya; Burns, Daniel R. en_US


Files in this item

Name Size Format Description
Chen_2009.pdf 1.476Mb PDF

This item appears in the following Collection(s)

Show simple item record

MIT-Mirage