(459f) Synthesis and Evaluation of Dipicolinic Acid (DPA) – Based Interwell Tracers for Reservoir Surveillance

Our efforts to address the known deficiencies of modern-day chemical tracing in hot and high salinity reservoirs has led to the adaptation of developed technology such that it touches upon multiple facets of tracer management, with particular emphasis on materials development and their subsequent detection. Fundamentally, this technology comprises classes of optically detectable and chromatographically distinguishable molecular tracers that serve as selective chromophore ligands for trivalent lanthanide metals capable of sensitizing their luminescence upon ligand-metal ion complexation, thus enabling high-sensitivity detection. Lanthanide-based chelation chemistry already has a known basis in applications involving the detection of biological entities; in particular, dipicolinic acid (DPA), a biomarker of bacterial spores, exhibits high-specificity binding to sensors containing Tb³⁺/Eu³⁺ metal ions. In continuing to exploit the optical properties of such systems, we herein report the synthesis of DPA-derived molecular inter-well water tracers, placing particular emphasis on backbone functionalization of native DPA to generate “barcodes” that can enable their simultaneous full-field deployment. Preliminary coreflood results benchmarking DPA against conventional fluorobenzoic acid (FBA)-based and ionic (KCl) tracers indicate that DPA exhibits similar breakthrough times, is non-retentive and also non-partitioning. We have also demonstrated that DPA and its variants are amenable to chromatographic separation and detection by high performance liquid chromatography (HPLC), providing ultra-trace limits of detection (LOD) using a method complementary to optical detection modalities. Studies regarding the physicochemical properties of the lanthanide ion complexes generated are being conducted concurrently alongside evaluation of synthesized tracer candidates, the integrity of which are also being evaluated via long-term thermal stability testing. We hope that the research conducted herein will ultimately lead to the deployment of new classes of chemical tracers capable of facilitating increased waterflood efficiency, particularly in mature reservoirs where optimization of oil recovery techniques requires high levels of detail.