Noel Black

Evaluation of rapid dual-tracer 62Cu-PTSM + 62Cu-ATSM PET in dogs with spontaneously occurring tumors

We are developing methods for imaging multiple PET tracers in a single scan with staggered injections, where imaging measures for each tracer are separated and recovered using differences in tracer kinetics and radioactive decay. In this work, signal separation performance for rapid dual-tracer (62)Cu-PTSM (blood flow) + (62)Cu-ATSM (hypoxia) tumor imaging was evaluated in a large animal model. Four dogs with pre-existing tumors received a series of dynamic PET scans with (62)Cu-PTSM and (62)Cu-ATSM, permitting evaluation of a rapid dual-tracer protocol designed by previous simulation work. Several imaging measures were computed from the dual-tracer data and compared with those from separate, single-tracer imaging. Static imaging measures (e.g. SUV) for each tracer were accurately recovered from dual-tracer data. The wash-in (k(1)) and wash-out (k(2)) rate parameters for both tracers were likewise well recovered (r = 0.87-0.99), but k(3) was not accurately recovered for PTSM (r = 0.19) and moderately well recovered for ATSM (r = 0.70). Some degree of bias was noted, however, which may potentially be overcome through further refinement of the signal separation algorithms. This work demonstrates that complementary information regarding tumor blood flow and hypoxia can be acquired by a single dual-tracer PET scan, and also that the signal separation procedure works effectively for real physiologic data with realistic levels of kinetic model mismatch. Rapid multi-tracer PET has the potential to improve tumor assessment for image-guide therapy and monitoring, and further investigation with these and other tracers is warranted.

Rapid Multi-Tracer PET Tumor Imaging With

Rapid multi-tracer PET, where two to three PET tracers are rapidly scanned with staggered injections, can recover certain imaging measures for each tracer based on differences in tracer kinetics and decay. We previously showed that single-tracer imaging measures can be recovered to a certain extent from rapid dual-tracer 62Cu-PTSM (blood flow) + 62Cu-ATSM (hypoxia) tumor imaging. In this work, the feasibility of rapidly imaging 18F-FDG plus one or two of these shorter-lived secondary tracers was evaluated in the same tumor model. Dynamic PET imaging was performed in four dogs with pre-existing tumors, and the raw scan data was combined to emulate 60 minute long dual and triple-tracer scans, using the single-tracer scans as gold standards. The multi-tracer data were processed for static (SUV) and kinetic (K1, Knet) endpoints for each tracer, followed by linear regression analysis of multi-tracer versus single-tracer results. Static and quantitative dynamic imaging measures of FDG were both accurately recovered from the multi-tracer scans, closely matching the single-tracer FDG standards (R > 0.99). Quantitative blood flow information, as measured by PTSM K1 and SUV, was also accurately recovered from the multi-tracer scans (R = 0.97). Recovery of ATSM kinetic parameters proved more difficult, though the ATSM SUV was reasonably well recovered (R = 0.92). We conclude that certain additional information from one to two shorter-lived PET tracers may be measured in a rapid multi-tracer scan alongside FDG without compromising the assessment of glucose metabolism. Such additional and complementary information has the potential to improve tumor characterization in vivo, warranting further investigation of rapid multi-tracer techniques.

^{18}{\hbox {F-FDG}}

Marine controlled-source electromagnetic (MCSEM) technology has been successfully established as an effective tool for offshore hydrocarbon (HC) exploration. In this paper we consider another application of the MCSEM method for HC reservoir monitoring. We demonstrate that EM methods can also be used for the monitoring of producing wells in connection with the enhanced recovery of hydrocarbons. We have developed a powerful new EM modeling technique based on the integral equation method with an inhomogeneous background conductivity (IE IBC). This new method and the corresponding computer software make it possible to model the EM response over a realistic complex model of a sea-bottom HC reservoir. The numerical modeling results demonstrate that the MCSEM method has the ability to map changes in resistivity caused by the production of hydrocarbons over time. In addition, the EM data help to visualize changes in the location of the oil-water contact within the reservoir. This result opens the possibility for practical application of the EM method in HC reservoir monitoring.

and Secondary Shorter-Lived Tracers

ABSTRACT A towed streamer electromagnetic system capable of simultaneous seismic and electromagnetic data acquisition has recently been developed and tested in the North Sea. We introduce a 3D inversion methodology for towed streamer electromagnetic data that includes a moving sensitivity domain. Our implementation is based on the 3D integral equation method for computing responses and Frechet derivatives and uses the re‐weighted regularized conjugate gradient method for minimizing the objective functional with focusing regularization. We present two model studies relevant to hydrocarbon exploration in the North Sea. First, we demonstrate the ability of a towed electromagnetic system to detect and characterize the Harding field, a medium‐sized North Sea hydrocarbon target. We compare our 3D inversion of towed streamer electromagnetic data with 3D inversion of conventional marine controlled‐source electromagnetic data and observe few differences between the recovered models. Second, we demonstrate the ability of a towed streamer electromagnetic system to detect and characterize the Peon discovery, which is representative of an infrastructure‐led shallow gas play in the North Sea. We also present an actual case study for the 3D inversion of towed streamer electromagnetic data from the Troll field in the North Sea and demonstrate our ability to image all the Troll West Oil and Gas Provinces and the Troll East Gas Province. We conclude that 3D inversion of data from the current generation of towed streamer electromagnetic systems can adequately recover hydrocarbon‐bearing formations to depths of approximately 2 km. We note that by obviating the need for ocean‐bottom receivers, the towed streamer electromagnetic system enables electromagnetic data to be acquired over very large areas in frontier and mature basins for higher acquisition rates and relatively lower cost than conventional marine controlled‐source electromagnetic methods.

Monitoring of Hydrocarbon Reservoirs Using Marine CSEM Method

Recent studies have inferred the feasibility of time-lapse controlled-source electromagnetic (CSEM) methods for the surveillance of offshore oil and gas fields. However, quantitative interpretations have not been shown to ascertain what information about the reservoirs that may be recovered. We present a 3D inversion study of synthetic time-lapse CSEM data for the lateral water flooding of a reservoir unit where the hydrocarbon accumulation is trapped by a thin dome structure. We demonstrate that even with few constraints on the model, the flooding front can be recovered from 3D inversion. In this paper, synthetic time-lapse CSEM responses are simulated with the threshold about the noise floor and subject to multiple 3D inversion scenarios. The time-lapse CSEM inverse problem is highly constrained though inherently 3D since the geometry of the reservoir is established prior to production from high resolution seismic surveys; rock and fluid properties are measured from well logs; and multiple history matched production scenarios are contained in dynamic reservoir models.

Three-dimensional inversion of towed streamer electromagnetic data

A towed streamer electromagnetic (EM) system capable of simultaneous seismic and CSEM data acquisition has been developed and tested in the North Sea. The towed EM data are processed and delivered as a time-domain impulse response. In this paper, we use 3D modeling and inversion to investigate the ability of the towed EM system to detect and characterize the Harding field, a typical North Sea-type target. The 3D model of the Harding field itself was constructed from dynamic reservoir simulations. We have compared our 3D inversion of time-domain towed streamer EM data with 3D inversion of conventional frequencydomain CSEM data. We observe similarities in the recovered models. Obviating the need for ocean bottom receivers, the towed-streamer EM system enables CSEM data to be acquired simultaneously with seismic over very large areas in frontier and mature basins for higher production rates and relatively lower cost than conventional CSEM.

3D Inversion of Time-lapse CSEM Data For Reservoir Surveillance

Recent studies have inferred the feasibility of time-lapse controlled-source electromagnetic (CSEM) methods for the monitoring of offshore oil and gas fields. The time-lapse CSEM inverse problem is highly constrained though inherently 3D since the geometry of the reservoir is established prior to production from high resolution seismic surveys; rock and fluid properties are measured from well logs; and multiple history matched production scenarios are contained in dynamic reservoir models. Using Archie’s Law, rock and fluid properties from dynamic reservoir simulations of the Harding field in the North Sea were converted to resistivity, from pre-production in 1996 to decommissioning in 2016. CSEM data were simulated for each state. We demonstrate how 3D inversion can be used for monitoring the oil-water contact from pre-production to end of oil production in 2011, and for monitoring of the gas-water contact 2011 to 2016 during gas production. In particular, we show that focusing regularization is able to recover sharp resistivity contrasts across the oil-water and gas-water boundaries, whereas smooth regularization fails to recover an adequate resistivity contrast.

3D inversion of towed streamer EM data — A model study of the Harding field and comparison to 3D CSEM inversion

Rapid multi-tracer PET, where two to three PET tracers are rapidly scanned with staggered injections, can recover certain imaging measures for each tracer based on differences in tracer kinetics and decay. We previously showed that single-tracer imaging measures can be recovered to a certain extent from rapid dual-tracer 62Cu-PTSM (blood flow) + 62Cu- ATSM (hypoxia) tumor imaging. Here we develop improved tracer-separation algorithms and evaluate signal-separation performance for rapidly imaging various combinations of F- FDG plus 62Cu-PTSM and/or 62Cu-ATSM. Dynamic imaging with these three tracers was performed in four dogs with prexisting tumors, and the raw scan data was combined to emulate dual- and triple-tracer imaging, using the single-tracer scans as gold standards. The multi-tracer data were processed for static (SUV) and kinetic (k1-k3, knet) endpoints for each tracer, followed by linear regression analysis of multi-tracer vs. single-tracer results. The FDG information was largely retained in these multi-tracer protocols. Static imaging measures (SUV) for FDG were accurately recovered, with r>0.99 in all protocols studied (four dual-tracer and one triple-tracer). Dynamic FDG imaging measures (k!-k3, knet) were well-correlated with single-tracer values (r>0.99). SUVs for PTSM and ATSM were also recovered well (r=0.97 and 0.92, respectively), and dynamic measures were recovered to varying degrees. The additional and complementary information obtained from PTSM and ATSM imaged simultaneously with FDG has the potential to improve tumor assessment for image-guided therapy and monitoring, warranting further development of the signal-separation algorithms.

3D Inversion of Time-lapse CSEM Data from Dynamic Reservoir Simulations of the Harding field, North Sea

Abstract Marine controlled-source electromagnetic (MCSEM) technology has been successfully established as an effective tool for offshore hydrocarbon (HC) exploration. In this paper we consider another application of the MCSEM method for HC reservoir monitoring. We demonstrate that EM methods can be successfully used for the monitoring of production wells in connection with the enhanced recovery of hydrocarbons. We have developed a powerful new EM modeling technique based on the integral equation method with an inhomogeneous background conductivity (IE IBC). This new method, and the corresponding computer software, make it possible to model the EM response over a realistic complex model of a sea-bottom HC reservoir. The numerical modeling results demonstrate that the MCSEM method has the ability to map changes in resistivity caused by the production of hydrocarbons over time. In addition, the EM data help to visualize changes in the location of the oil-water contact within a reservoir. This result opens the possibility for practical application of the EM method in HC reservoir monitoring.

Measurement of secondary tracers in FDG tumor imaging by rapid multi-tracer PET

Michael S. Zhdanov, Masashi Endo, Noel Black, Lee Spangler, Stacey Fairweather, Andrew Hibbs, George A. Eiskamp and Robert Will present a feasibility study of permanent electromagnetic (EM) monitoring of CO2 sequestration in deep reservoir using a novel borehole-to-surface EM (BSEM) method.