Logging-while-drilling (LWD) imaging solutions have been a part of the oil and gas formation evaluation technologies portfolio for quite some time. Lately, most LWD solutions have evolved to address new challenges in complex environments. This paper discusses advanced LWD electrical imaging technology and its recent use to help solve persistent challenges related to both well placement and reservoir characterization.

In a thin heterogeneous carbonate reservoir constrained by a tight control window of placement, the high-resolution, real-time laterolog electrical image proved to be an optimum solution to help determine well placement for maximizing reservoir contact. Running wireline imaging for fracture identification, inflow control device (ICD) completion design, and reservoir characterization can impose many risks related to well trajectory, borehole stability, borehole shape, and well control. However, an alternative LWD high-resolution laterolog electrical imaging solution—validated by the example described in this paper from a carbonate reservoir in the Middle East—demonstrated its capability to achieve the same objectives in those environments while avoiding the above-mentioned risks.

Well placement (geosteering) is dependent on control points from offset wells and LWD tool measurements that help identify the location of the bottomhole assembly (BHA) down hole in real time to enable on-the-fly decisions regarding well placement in the sweet zones. Imaging applications that outline a 360° view of the borehole are commonly used to identify formation dips, allowing geosteering specialists to make well trajectory adjustments. This paper illustrates an example of a resistivity contrast in a carbonate reservoir capped by a tight resistive boundary. The real-time LWD high-resolution electrical image helped identify formation dips and features of sublayers within the zone of interest. Noticeable changes in the sublayers' dip were most likely related to a boundary dip angle change. After adjusting the drilling assembly trajectory to account for that change, the LWD electrical image clearly illustrated parallel lines, indicating the well trajectory was smoothly following the same formation dip. In addition, the LWD focused resistivity tool capability to record high-resolution images while drilling proved to be an effective alternative solution to wireline imaging in these environments.

You can access this article if you purchase or spend a download.