Abstract

As production logging technology advances, more confident results are achieved in multiphase horizontal wells. There are a number of wells with unfavorable completions for production logging. In addition, operational difficulties are observed from time to time posing challenges. In any case, confidence in the determination of fluid entry intervals is required. Because of dynamic data acquisition, real time decisions are needed.

In this paper, we present two field examples of challenging integrated production logging in horizontal wells. The first example shows identification of water entry with a compact integrated production logging tool in a cased horizontal well. The tool includes five miniaturized spinners for phase velocity, as well as six electrical and six optical probes for hold up. All sensor measurements are taken at the same depth level simultaneously. For the first time, a production logging job was transmitted in real time to the office for data quality control and decision making. Although unexpected difficulties were observed, the entry intervals of water and oil were identified as the job progressed. The second example demonstrates the identification of water entry in a pre-perforated (un-cemented) liner that is considered to be unfavorable condition for production logging. In order to detect water flow inside or outside the pre-perforated environment, a different tool string was used compared to the first example.

The results shown in this paper provide field examples of challenging conditions in horizontal production logging operations and interpretation. Efficient integrated production logging improves understanding of well behavior and reservoir characterization in challenging conditions.

Introduction

Increased water production can significantly reduce well performance and result in decreased oil production. The detection of water entry intervals and production profile provide useful information for understanding reservoir dynamics and well performance. For maximum productivity and choosing well trajectories, the evaluation of offset well performance is crucial. Production logging provides not only the detection of unwanted fluids but also measures effective well length that is needed in well testing evaluation for complete well performance analysis. In addition, the length and the number of entries provide information about the characteristics of the intervals. Eventually, the integration with reservoir and geological data yields more accurate reservoir characterization. After confident determination of water entry intervals, remedial actions can be assessed and shut off or re-completion can be conducted, if feasible.

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