Jl. Mari et al., AN EXAMPLE OF ACOUSTICS AND VERY HIGH-RESOLUTION SEISMIC IN A HIGHLY DEVIATED WELL, Revue de l'Institut francais du petrole, 49(6), 1994, pp. 615-625
Citations number
10
Categorie Soggetti
Energy & Fuels","Engineering, Chemical","Engineering, Petroleum
Acoustic logging is conventionally used to determine the slowness of f
ormations. The total-field recordings made in highly-deviated or horiz
ontal boreholes can be processed to provide microseismic borehole cros
s-sections having a lateral investigation range of some ten meters aro
und the drain hole. This article describes the results of experiments
performed in a limestone quarry located in Burgundy, France. A highly
deviated borehole (10 degrees) was drilled into a ''white oolite'' geo
logic unit that was about 80 m thick. Acoustic logs and high resolutio
n seismic were recorded in the deviated borehole. In acoustic logging,
two sets of data were recorded: a constant-offset cross-section and a
common shotpoint with a great number of traces and a centimetric dist
ance between traces. Data processing brought out reflections inside th
e white oolite several meters away from the drain hole. The acoustic l
og was not able to determine the top and bottom of the white oolite un
it. This goal was partially achieved by very high resolution seismic i
n the borehole. This type of seismic works in a frequency band interme
diate between conventional borehole seismic and acoustic logging. It r
equires the development of special tools, particularly with regard to
the borehole sources. A common shotpoint gather of very high-resolutio
n seismic data obtained with a prototype source of the impulsional typ
e shows reflections corresponding to reflectors situated several tens
of meters (approximately 40 m) away from the drain hole. The results o
f these experiments showed the potential of acoustic logging and high-
resolution borehole seismic for describing a reservoir unit at differe
nt scales.