Although various logging challenges in highly deviated and horizontal wells have been addressed in many previous studies, only a few investigations have focused on emulsion diagnosis and multiphase production log (MPL) solutions in such difficult conditions. The emulsion discussed in this paper is water-in-oil emulsion, in which water is present in the form of droplets dispersed in oil. This is generally expected to happen in a high velocity, turbulent flow regime, and in a low density contrast between oil and water. The impact of water emulsion is the inability to identify and quantify water entries using the standard holdup measurement arrays, because the water droplets have the same conductivity as oil and travel at the same velocity as oil, regardless of well deviation.
A novel workflow and methodology were established for successful diagnosis of this emulsion downhole to be able to perform inflow profiling for these problematic wells, using information from different sources of data: multiphase production logging tool (MPLT), pulsed neutron logging tool (PNLT), and surface fluid sampling. The workflow includes job preparation, real-time monitoring during logging operation, and post-job data interpretation.
The optimized workflow was applied to field examples for successful diagnosis of the emulsion and the integrated logging solution to overcome this challenge in horizontal wells. This led to the determination, with high confidence, of the downhole flow profile and to the accurate quantitative identification of the source of water production. The information can then be used to plan suitable well intervention, without which the reservoir and/or field development could not be optimized.
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