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Abstract

Recently, new oil-water partitioning tracers, suitable for use in oil reservoirs to estimate remaining oil saturation in inter-well regions, were introduced and tested in a mature oilfield. In this paper we present the first application of the new partitioning tracers in relation to an ongoing EOR operation in a sandstone reservoir in the Bockstedt field in Northern Germany. The new class of tracers can be used assess inter-well oil saturation in so-called partitioning inter-well tracer tests (PITTs). The PITT is a non-destructive and non-intrusive test to measure oil saturation between injectors and producers in a reservoir. The test is based on recording the time delay experienced by a partitioning tracer, compared to a non-partitioning (or passive) tracer, when the tracers are transported through an oil-reservoir. The time delay is due to separation between passive and partitioning tracers as they move through the partially oil-filled reservoir. This delay is related to the oil saturation as well as the tracer's partition coefficients that govern the distribution of tracer between the oil and water phases. By recording the time delay, and measuring the partitioning coefficients in the lab, PITTs can be applied to measure oil saturation (So). To our knowledge, the PITT is the only known way to measure the remaining oil in the entire swept region between wells. Such tests are frequently used to investigate the presence and remediation of non-aqueous phase liquids (NAPLs) in ground-water applications. However, such tests are very rare in the oil industry due to harsh conditions and lack of suitable tracers. PITT tracers suitable for oil-reservoir applications appropriate partitioning characteristics between oil and water. In addition, all tracers must be stable during sample storage, have excellent analytical sensitivity, thermally stable at relevant temperatures, environmentally acceptable and unique in the reservoir environment. The partitioning tracer candidates, which qualified for sandstone reservoirs in this paper, fulfil all required criteria and it is therefore our hope that this will be a significant breakthrough for measurements of inter-well saturations in relation to EOR and IOR operations.

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/content/papers/10.3997/2214-4609.201412118
2015-04-14
2024-03-29
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201412118
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