An operator drilled and completed a single well bore consisting of an 8-1/2" open hole with 6-5/8" completion screens. At first oil and extending into long term production they wanted to:
In total three TRACERCO Diagnostics™ controlled release water-soluble chemical tracers and three TRACERCO Diagnostics™ controlled release oil-soluble chemical tracers were identified as compatible to meet project objectives. As the 6-5/8" screens had been manufactured each of the tracers was applied to the outside of the wire wrap screens and protected using a shroud by Tracerco’s Houston based operational team. Each of the screens was shipped to the site and run in hole at zones of most interest to the customer.
Sampling and Analysis
Sampling for the tracer was performed at different stages of well production from well test to production flow ‘ramp up’. The initial sampling phase was taken during the well test via a surface well test package. Sampling began at ‘bottoms up’ and continued for 12 days. The frequency of samples taken was based on the flow rate of well production and previous project experience. Initially a production sample was taken every 10 minutes. This was reduced to one sample every 30 minutes by the completion of the well test phase. Samples were analysed at the Tracerco Tracer Technology Centre using modern analytical Gas Chromatography instrumentation. In parallel, samples were analysed using portable analysis equipment to compare results and prove that onsite analysis could be achieved.
Results and Interpretation
The analysis showed that production was from the ‘heel’ and ‘mid’ sections of the well bore, whilst the tracer located at the ‘toe’ of the well was measured around background levels. During this initial phase the only water producing was due to the return of completion fluids within the wellbore. The initial ‘field trial’ of on-site analysis equipment also proved to be successful, with the data showing good, comparative trends in comparison to lab-based equipment. Ongoing sampling and analysis will continue to determine the time at which the toe of the well starts to contribute to well flow, when produced water is detected and determine where it is flowing into the well downhole. In addition, onsite analysis shall be used during the next well completion to allow instant results at first oil in order that wellbore intervention can be accomplished if deemed necessary.
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