Extra-deep resistivity has been used successfully since 2004 in Norway for reservoir navigation relative to distant bed boundaries. The need for improved reservoir understanding and geosteering decisions in complex heterogeneous reservoirs has led to the development of a new extra-deep azimuthal resistivity (EDAR) tool. Inversion results of deep azimuthal resistivity measurements are bridging the gap between traditional logging-while-drilling (LWD) measurements and seismic data, and can image reservoir architecture during drilling tens of meters away from the borehole. It is possible to delineate multiple geologic layers directionally away from the borehole with resistivity contrasts without probing the layers directly. The non-unique nature of inversions leads to questions about the reliability and accuracy of the inversion results.

This paper will present measurement and inversion results from an airhang test and a land-based drilling facility, testing the tool and interpretation methodology by comparing results with known geometry. During the airhang test, the tool was suspended at specified distances to a water surface to verify the response. The measured response from this test matched the expectations very well. A field test at a drilling site was conducted to check the performance in a realistic downhole setting. The well was landed horizontally in the target zone using the new EDAR system. The verification step determined the ‘true’ top boundary, which was accomplished by sidetracking from the original hole and penetrating the target top at a point previously interpreted from the resistivity data. The verification tests will be discussed in detail, in addition to a general overview of the hardware and interpretation comprising the measurement.

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