Smalley, Andy1, Mitch D. Pavlovic2, Stephen Dymmock2
(1) Baker Atlas, Milan, Italy (2) Baker Atlas, Houston, TX
The use of high resolution borehole imaging devices has been well demonstrated for the characterisation of reservoirs in recent years. Such high resolution images, until recently, could only be acquired in wells drilled using conventional conductive mud systems. The recent development of micro-resistivity imaging devices for use in wells drilled with non-conductive mud systems has helped to overcome this limitation. This paper presents the results of an interpretation of data acquired from a new micro-resistivity imaging device. The simultaneously acquired circumferential acoustic borehole images further enhanced the structural interpretation. By integrating this interpretation with Dielectric data, a detailed lithological interpretation was possible, allowing a detailed net sand estimation to be carried out.
The well was drilled on the apex of a thrust-related anticline. Bedding features identified from the borehole images display trends consistent with the seismic interpretation, demonstrating a flat overall structure gently dipping to the SW. A very gradual increase in mean dip magnitude was observed as the well trajectory approaches the SW limb.
Given that sandstones in Adriatic reservoirs are volcanic-sourced, they tend to be radioactive and therefore not readily identified using a gamma ray log. Net sand estimation has hence proved problematic using conventional logging suites alone. A lithological classification of the logged interval was carried out by integrating the borehole image data with the dielectric curve. The distribution of sand, silt, shale and heterolithics over the logged interval was interpreted. Subsequently, an accurate net sand estimation was carried out.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.