Low resistivity and low contrast (LRLC) environments are challenging for existing deep (DAR) and ultra-deep azimuthal resistivity (UDAR) technologies. The new generation of Logging While Drilling (LWD) ElectroMagnetic (EM) Azimuthal Resistivity technology named “Multi Depth Azimuthal Resistivity” (MDAR) platform has advanced features and considerably more measurements facilitating running multiple inversions of azimuthal measurements which are critical in LRLC environment. Featuring a unique design of triaxial collocated antennas, close proximity to the bit transmitter and increased signal-to-noise ratio, the MDAR technology proven to be valuable for confidently landing a well in a target thin sand lobe with low resistivity contrast.

This paper demonstrates how combining real time Reservoir Mapping Inversions (RMI), that are referenced at the midpoint of the transmitter-receiver array, can resolve the reservoir structure around the wellbore while At-Bit Inversions (ABI), that are referenced at the transmitter position right behind the bit, provides the optimal combination to make informed decisions to land a well in LRLC environment.

Landing sections play a critical role in well placement efficiency as it will lead to saving or losing valuable reservoir exposure. Some current technologies with either DAR or UDAR depths of detection can resolve and map the reservoir structure around the wellbore, however they have inherent limitations increasing the level of uncertainty of inverted “apparent” resistivity and distance to boundary depending on the surrounding environment. The MDAR provides the inputs that enables the inversion to reduce the uncertainty in the position of formation boundaries and the structural dip allowing for timely landing decisions to be made.

MDAR was employed in LRLC environment to optimize well landing and determine the impact of the new generation hardware features and newly developed inversion on the accuracy and efficiency of the operation.

The MDAR provides significantly improved measurements and signal-to-noise ratio, the inversion depicts increased sensitivity to formation resistivity properties as compared to current technologies.

MDAR platform was deployed in the landing section to target a thin (3–7 ft TVD) sand lobe in a low resistivity low contrast environment. As the wellbore deviation increased towards lateral, several formations with different geological properties were mapped below the wellbore with the Reservoir Mapping Inversion depth of investigation exceeding 70 ft TVD. The geological structure was confidently mapped in terms of structural dip and position. The near bit ABI allowed for first detection of structural changes.

Once the target reservoir was entered, the value of the MDAR ABI was proven in providing real time mapping of multiple thin layers with high confidence even in low resistivity contrast environment outperforming current DAR and UDAR technologies. The ABI allowed confident landing decisions in the target sand lobe saving substantial footage (1200 ft MD) compared to the predrill plan.

The new MDAR technology has improved hardware and enhanced sensitivity for low resistivity contrast formations. With triaxial collocated antennas, improved signal-to-noise ratio, multiple inversions, the lowest available firing frequencies and the closest near bit inversion, the MDAR platform can confidently place the wellbore in this most challenging environment. Realtime delivery of 1D, 2D and 3D interpretations and answer products increases the reservoir understanding and the confidence to make timely critical decisions to accurately place the well.