Steam-assisted gravity drainage (SAGD) technology, although a relatively new oil recovery method, has already proved its value in economic development of heavy-oil sands in Western Canada. The SAGD process requires a lifetime monitoring of steam chamber growth to optimize reservoir development, improve oil recovery, and minimize environmental impact. Operators have widely used pulsed neutron well logs to monitor their life cycles of oil sand reservoirs. Time-lapse pulsed neutron logs acquired in observation wells enable operators to effectively track the growth of the steam chamber and identify the changes of formation fluid saturations. We present high-temperature pulsed neutron logging technology and an algorithm to quantify steam, heavy oil and water saturations in SAGD wells. One of the major challenges in well logging operation is to withstand the thermal shock from the steam chamber. Reservoir temperature often varies abruptly, by as much as 250 degrees C in a very short interval, so the logging tool must be stable in drastic temperature variations. Well logging conditions such as a steam-filled wellbore, extra completion hardware and bad cement quality are challenging factors as well. Furthermore, formation fluid saturation analysis in Canadian oil sands is typically complex because the formation water salinity is relatively fresh but varies, clay properties are not homogeneous, and SAGD operations create conditions in which three-phase fluids coexist in the formation. These environmental conditions make it difficult to rely only on commonly used thermal neutron capture cross-section measurements (formation sigma). In this paper, case study examples present the above-mentioned challenges and solutions to identify the multi-component formation fluids. The multi-detector pulsed neutron well logging instrument has been modified with a custom-designed heat flask to handle the extreme temperature variations in the SAGD environment. This heat-flask equipped instrument ensures a stable data acquisition in the presence of rapid and extreme temperature variation and enables a prolonged and time-efficient operation through effective heat management. For saturation analysis, we demonstrate an advanced algorithm to quantify three fluid components using a combination of gamma ray ratio and carbon/oxygen (C/O) measurements.

Monoamine oxidase (MAO) are flavoenzymes that metabolize neurotransmitter, dietary and xenobiotic amines to their corresponding aldehydes with the production of hydrogen peroxide. Two isoforms, MAO-A and MAO-B, are expressed in humans and mammals, and display different substrate and inhibitor specificities as well as different physiological roles. MAO inhibitors are of much therapeutic value and are used for the treatment of neuropsychiatric and neurodegenerative disorders such as depression, anxiety disorders, and Parkinson’s disease. To discover MAO inhibitors with good potencies and interesting isoform specificities, the present study synthesized a series of 2,1-benzisoxazole (anthranil) derivatives and evaluated them as in vitro inhibitors of human MAO. The compounds were in most instances specific inhibitors of MAO-B with the most potent MAO-B inhibition observed for 7a (IC50 = 0.017 µM) and 7b (IC50 = 0.098 µM). The most potent MAO-A inhibition was observed for 3l (IC50 = 5.35 µM) and 5 (IC50 = 3.29 µM). It is interesting to note that 3-(2-aminoethoxy)-1,2-benzisoxazole derivatives, the 1,2-benzisoxazole, zonisamide, as well as the isoxazole compound, leflunomide, have been described as MAO inhibitors. This is however the first report of MAO inhibition by derivatives of the 2,1-benzisoxazole structural isomer. Graphical abstract

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Steam flooding is an essential recovery process in developing heavy oil reservoirs. Operators typically drill and case observation wells to monitor the movement of the injected steam and changes in heavy oil and water saturations. This in-well surveillance is performed using pulsed neutron well logging techniques. Pulsed neutron well logging technology has been used for more than 60 years to determine formation fluid saturation behind casing. We introduce a next-generation slim multi-detector pulsed neutron well logging tool. The new pulsed neutron tool integrates an upgraded pulsed neutron generator, lanthanum bromide scintillation detectors, and an improved electronics system. A robust data analysis technique is another vital component of through-casing multiphase formation fluid quantification. A conventional method for analyzing three-phase saturation uses two pulsed neutron logs in sequence. We have adopted a simultaneous analysis approach that combines two pulsed neutron measurements simultaneously to evaluate the volumes of multiphase fluid components. We present a case study of oil sands produced by the steam-assisted gravity drainage (SAGD) method. We also show comparisons of data acquisition with the previous-generation and new pulsed neutron tools, operating time, and data quality. We acquired time- and energy-based gamma-ray spectra from multiple detectors to extract key pulsed neutron measurements such as ratios of inelastic and capture gamma rays and carbon/oxygen ratios. Time- and energy-spectra-based salinity-independent nuclear measurements were combined to compute three-phase formation fluid saturation. The new tool acquired data of the same quality at least three times faster than the legacy tool. The new tool that offers three improved features (higher pulsed neutron outputs, denser scintillation detectors, and high-speed digital electronics) combined with a new acquisition technology that records time- and energy-spectra-based pulsed neutron data sets simultaneously enables faster reservoir surveillance. Operators using thermal methods for heavy oil recovery must understand the current underground steam distribution. This affects steam injection optimization and determines subsequent reservoir management activities. A technique for delineating steam, heavy oil, and water through cased monitoring wells was improved by incorporating a new well logging tool, an innovative acquisition mode, and an advanced nuclear data analysis workflow.