Tracer technology has been increasingly used in inter-well tests to investigate reservoir performance, reservoir connectivity and residual oil saturation for providing useful information to improve decision making in reservoir management. To develop high-sensitive analytical methods for tracer detection has been one of the most central challenges to realize ubiquitous full field tracer deployment in large reservoirs. We presented using solid phase extraction (SPE) method to separate tracer molecules from high concentration of salts in produced water and enrich the tracer molecules onto SPE sorbents. Since no single commercially available SPE column could achieve satisfactory recovery efficiency for mixed barcoded tracers, we have designed new SPE sorbent formulations by combing commercially available sorbent materials. The reconstructed multi-functional SPE sorbents allow efficient removal of salts and enrichment of the amount of these molecular compounds, typically by 100 times or more, from produced water samples. For commercially available tracers such as fluorinated benzoic acids (FBAs) and Aramco’s newly developed Advanced Barcoded Tracers (ABTs) implemented in the oilfield in KSA, when the field samples were treated using the new SPE materials developed here, these tracer compounds can be readily separated from salt produced water and preconcentrated from part-per-trillion (ppt) to above part-per-billion (ppb) level of concentration in water, which enables the detection of these tracer compounds from otherwise undetectable levels. By bringing the concentrations of the analyte above the detection limits by conventional instrumental analysis such as high-performance liquid chromatography (HPLC) and fluorescence spectroscopy, less tracer materials need to be applied in oilfield application. This approach directly addressed key limitations in detection sensitivity of tracer compounds at ultra-low concentrations from produced water samples and has been successful applied to tracer analysis in recent field trials in KSA.

High-efficient method for separation and enrichment of tracers from field produced water samples

ACS Spring 2022

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