Abstract: A method is disclosed for real-time (well-site) resistivity anisotropy determination using array lateral logs or any other unfocused, lateral-type measurements, and array induction logs or any other focused, induction-type measurements. Near-vertical wells with a deviation angle of less than 30 degrees are considered. Since with a lateral log, at each logging depth the injected current has both horizontal and vertical components, the data contains information related to both horizontal (Rh) and vertical (Rv) resistivities. With array induction tool, the induced current in near-vertical wells has only a horizontal component, and the induction data contain information related to Rh only. Having those two data sets acquired in the same well, it is possible to instantly estimate the formation resistivity anisotropy using square of a ratio between borehole and invasion corrected lateral and induction focused logs.

Abstract: A method for determining formation resistivity anisotropy in a wellbore environment. The method of the present invention effectively extends the dynamic range of the existing well logging service of the multi-component induction tool, allowing the use of this service in wells drilled with conductive WBM systems. A sequential inversion processing of galvanic array lateral log HDLL/MLL data or DLL/MLL and also multi-component induction log (3DEXSM) data is used. The formation resistivity structure of the near wellbore environment is determined using the galvanic measurements of the array lateral log tool.

Abstract: A method is disclosed for real-time (well-site) resistivity anisotropy determination using array lateral logs or any other unfocused, lateral-type measurements, and array induction logs or any other focused, induction-type measurements. Near-vertical wells with a deviation angle of less than 30 degrees are considered. Since with a lateral log, at each logging depth the injected current has both horizontal and vertical components, the data contains information related to both horizontal (Rh) and vertical (Rv) resistivities. With array induction tool, the induced current in near-vertical wells has only a horizontal component, and the induction data contain information related to Rh only. Having those two data sets acquired in the same well, it is possible to instantly estimate the formation resistivity anisotropy using square of a ratio between borehole and invasion corrected lateral and induction focused logs.

Abstract: A method for determining formation resistivity anisotropy in a wellbore environment. The method of the present invention effectively extends the dynamic range of the existing well logging service of the multi-component induction tool, allowing the use of this service in wells drilled with conductive WBM systems. A sequential inversion processing of galvanic array lateral log HDLL/MLL data or DLL/MLL and also multi-component induction log (3DEXSM) data is used. The formation resistivity structure of the near wellbore environment is determined using the galvanic measurements of the array lateral log tool.

Abstract: In highly deviated wells or when the relative dip angle between formation layering and wellbore axis is large, array induction measurements exhibit erratic spikes, misleading curve separations, and inaccurated resistivity values, preventing log analysts from accuratly evaluating invasion and formation resistivities. Our newly developed deviated-well software focusing (DSF) method that is derived from the Born approximation simultaneously accounts for all these dipping effects. The induction response is separated into two portions: a background response and a perturbation respones. An inhomogeneous, anisotropic background formation model is used to calculate the background response, and the perturbation response is interpreted through a software focusing technique. The combination of the two solutions is the final result.

Abstract: In highly deviated wells or when the relative dip angle between formation layering and wellbore axis is large, array induction measurements exhibit erratic spikes, misleading curve separations, and inaccurate resistivity values, preventing log analysts from accurately evaluating invasion and formation resistivities. To address these problems, various correction methods and inversion techniques have been developed. The correction methods, however, only yield satisfactory results when the relative dip angle is low to moderate, and inversion techniques are typically very time consuming. Conventionally, dipping bed effects are considered in terms of a charge effect and a volumetric effect. As even more complex earth models are considered, we find that formation anisotropy also exaggerates the dipping effect, manifested by misleading curve separations in the array instrument readings. Our newly developed deviated-well software focusing (DSF) method simultaneously accounts for all these dipping effects.

Abstract: A method for enhancing the axial resolution of conductivity well log measurements of in earth formation zones radially distal from a wellbore. The method includes calculating differential axial resolution information present in measurements of the conductivity of a zone radially proximal to the wellbore by low pass filtering the proximal zone measurements so as to have the same axial resolution as the measurements of earth formations radially distal from the wellbore, and subtracting the low pass filtered measurements from the measurements of the proximal zone. The differential axial resolution information is projected to conductivity values which would obtain if the proximal zone conductivity were equal to the distal zone conductivity. The projection is calculated by determining a projection factor, which is related to a weighted average of a ratio of conductivity in the distal zone with respect to the conductivity in the proximal zone.