An operator needed to identify water ingress locations across a 3-branch multi-lateral well to establish the accuracy of the reservoir simulation model. Such confirmation is invaluable in well production optimisation.
Tracerco was therefore contacted to provide controlled release tracer technology to establish where water ingress was occurring over an extended time period.
In total 11 controlled release water-soluble chemical tracers were required to meet the project objectives. These were carefully selected to deliver the required release rates and the desired detectability during analysis. The tracers were formulated into a matrix to provide controlled release and applied to specific screen joints.
During well production, surface samples were captured and analysed at Tracerco using sensitive analytical Gas Chromatography instrumentation combined with optimised tracer detection methodology.
Application of the Technology
Each controlled release chemical tracer was:
The screen was then sealed to protect against water intrusion whilst awaiting deployment.
Sampling and Analysis
The customer began sampling as the water cut approached 7%. One sample per week was taken over a 12 week period.
Tracerco analysed the samples, which proved that water was being produced across all three laterals.
Water ingress was detected in order of production. Firstly from the mid-section, then the heel and finally the toe of the lateral. Each event was detected at day one, 16 and 23 after the start of production.
Water production into this lateral detected firstly, in order, from the toe section followed by the mid-section and finally the heel section.
Throughout sampling water ingress was detected, initially at a high concentration and subsequently levelling off more consistently.
After 12 weeks of analysis, it was concluded by the customer that the data matched water production expectations predicted by the reservoir simulation model reasonably well. The tracer analysis had provided invaluable information about time and position of water break-through along the three individual branches of the well.
Calculations showed that less than 30% of tracer material was recovered over the period of the sampling schedule allowing a further six months monitoring to be available to the operator if needed.
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