Abstract
Is it a good idea to drill dual-lateral wells in a differentially depleted carbonate formation? The question is difficult. However, a state-of-the-art production-logging tool brought an answer that sanctioned the re-entry drilling program of this offshore field in the Persian Gulf.
The new-technology production services platform equipped with eight electrical e-probes for flow- imaging capability was run on coiled tubing for the first time in this offshore field to characterize the production of a new dual-lateral well. The main objective was to evaluate the total contribution of the horizontal drains. However, since the well was perforated in the different layers crossed by the well path, another critical objective was to determine the need for a stimulation program or a new completion design. Reservoir pressure in the different layers was expected to be non-uniform, so an additional objective of the logging operation was to obtain information on the differential depletion.
Production logging in highly deviated wells is difficult with standard sensors. One reason is that a conventional tool using differential pressure cannot measure fluid density. Moreover, flow regimes can be extremely complex, giving rise to phenomena such as water re-circulation, which is common in slanted wells and impossible to measure with a simple production logging string.
The data showed that both legs are contributing equally to the total production and observed water re-circulation on the bottom of the well. The perforations are not contributing to the total flow. Moreover, a crossflow observed during shut-in conditions suggested different pressure levels in the two layers.
This paper describes the logging operation and discusses how the results helped optimize the re-development plan of this aging field.
