Drilling of multilateral wells has increased significantly over the past few years as one of the reservoir development strategies to maximize well productivity through maximizing reservoir contact (MRC). These complex wells impose big challenges with respect to well accessibility for rigless well intervention. Means to access those wells were developed to perform conventional coiled tubing (CT) operations, such as reservoir stimulation.

One of the existing challenges is to perform production logging in these complex wells to quantify oil and water contribution of each open hole lateral and pinpoint fluids entry, mainly deep water inside these laterals.

This challenge was encountered in a multilateral oil evaluation producer, which was drilled in a carbonate oil reservoir but died shortly after being put on production due to high water production from an unknown source. This necessitates the logging of each of the well's laterals to identify the water contribution intervals to allow for the proper remedial action on this well, as well as to determine the optimal well completion for this type of reservoir, including inputting to geological modeling.

At present, there is no single production logging tool (PLT) that can be utilized to log each lateral selectively. Therefore, a combination of a multilateral tool along with a reservoir saturation tool was utilized to locate and access laterals selectively and to record a pulsed neutron log to determine the produced water velocity across each of the laterals. The pulsed neutron log was combined with three phase hold-up logs allowing the generation of production profiles of each lateral as well as the detection of water entries across these laterals.

This paper discusses the planning, execution and results evaluation of the logging job on an openhole multilateral oil producer along with all the techniques, which were employed to overcome challenges encountered along the way to acquire the best possible data on each lateral.

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