The multi-component induction tool (3DEXSM was run to re-evaluate and reduce uncertainty in reserves estimates of several laminated shaly sand sequences in a number of Kuwaiti reservoirs. The measurements were used to derive resistivities parallel and orthogonal to the formation bedding. The anisotropic resistivity data was then used to derive the true resistivities of thin sand beds, beds much below the resolution of induction tools. The wells logged presented significant challenges including a variety of borehole environments. The borehole sizes ranged from 6.125 in. to 12.25 in. The borehole fluids included both low and high salinity water-based muds, as well as oil-based muds. We successfully recorded high quality data in a 12.25-in. well with very high salinity mud and extensive breakouts. Further complicating the situation was that some of the intervals were logged in deviated holes and many of the laminated formations were deeply invaded with the highly saline mud filtrate. Conductive well bore environments, deep invasion and tool eccentricity are often regarded as serious impediments to successfully logging multi-component instruments and deriving accurate vertical and horizontal resistivities in electrically anisotropic formations. However, the multi-component tool makes measurements at ten frequencies and in these wells multi-frequency processing effectively eliminated the perturbing environmental effects and produced a robust and reliable formation resistivity and anisotropy. The multi-component induction data, the multi-frequency processing and laminated shaly sand analysis were successfully used to reduce uncertainty in reserves computations of the North Kuwait reservoir laminated sands.

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