New correlations for density of methane-free sodium chloride brine and solubility of methane in sodium chloride brines, valid over wide ranges of pressure, temperature, and salinity, are presented. Both correlations agree with the best available measurements within experimental error over most of the range of validity. These new correlations are combined with published correlations for methane partial molar volume to provide accurate and internally consistent estimates of brine density, specific volume, formation volume factor, and coefficient of isothermal compressibility at pressures above or below the bubble point pressure. The brine density correlation is valid for temperatures from 0 to 275 ° C (32 to 527 ° F), pressures from 0.1 to 200 MPa (14.5 to 29,000 psi), and sodium chloride content from 0 to 6 moles/kg H2O (0 to 26﹪ by weight). The methane solubility correlation is valid for temperatures from 20 to 360 ° C (68 to 680 ° F), pressures from 0.9 to 200 MPa (130 to 29,000 psi), and sodium chloride content from 0 to 6 moles/kg H2O (0 to 26﹪ by weight). A modification of an existing correlation for brine viscosity is also presented, extending its range of applicability to temperatures between 20 and 300 ° C (68 to 572 ° F), pressures between 0.1 and 200 MPa, and salinity between 0 and 5.4 moles NaCl/kgH2O (0 to 25﹪ NaCl by weight). Introduction Oil companies today produce in excess of 33 million cubic metres of water per day (210 MMbbl/day). The associated cost of handling this water production is estimated to exceed $40 billion per year(1). Understanding and dealing with these costs requires accurate knowledge of the water properties. Properties such as density, viscosity, and solubility affect the volume and movement of water through the reservoir, in the well bore, and at the surface facilities. As water production continues to increase, so does the importance of our understanding of the properties of the produced water. Many experimental studies of the behaviour of systems comprising water, sodium chloride, and methane have been reported in the physical chemistry literature during the last 25 years. By and large, the results of these studies have not been widely disseminated within the petroleum engineering community. In this paper, we present new correlations based on the published data for estimating those properties of primary interest to the petroleum engineer, namely the density, specific volume, methane solubility, formation volume factor, coefficient of isothermal compressibility, and viscosity. The next two sections of the paper discuss the development of the new brine density and methane solubility correlations. The third section shows how the brine density and methane solubility correlations may be combined with previous work to calculate internally consistent values for reservoir brine density, specific volume, coefficient of isothermal compressibility, and solution gas-water ratio at pressures above or below the bubble point pressure. The final section presents a modification of a published brine viscosity correlation, extending its range of applicability to temperatures of 300 ° C (572 ° F) and pressures of 200 MPa (29,000 psi).

Introduction: One sober consequence of the current epidemic of diabetes mellitus is that an increasing number of people world-wide will partially or completely lose their sight to diabetic retinopathy. Clinically, the sight-threatening complications of diabetes are diagnosed and treated based on visible retinal lesions (e.g., dot-blot hemorrhages or retinal neovascularization). However, such anatomical microvascular lesions are slow to respond with treatment. Thus, there remains an urgent need for imaging biomarkers that are abnormal before retinal lesions are visibly apparent and are responsive to treatment. Areas covered: Here, the development of new MRI methods, such as manganese-enhanced MRI, for evaluating early diabetes-evoked retinal pathophysiology, and its usefulness in guiding new treatments for diabetic retinopathy are reviewed. Expert opinion: In diabetic retinopathy, not all important diagnostic and prognostic needs are well served by optical methods. In the absence of gross anatomy changes, critical times when drug intervention is most likely to be successful at reducing vision loss are missed by most light-based methods and thus provide little help in guiding diagnosis and treatment. For example, before clinical symptoms, is there an optimal time to intervene with drug therapy? Is a drug reaching its target? How does one assess optimal drug dose, schedule, and routes? How well do current experimental models mimic the clinical condition? As discussed herein, MRI is as an analytical tool for addressing these unmet needs. Future clinical applications of MRI can be envisioned such as in clinical trials to assess drug treatment efficacy, or as an adjunct approach to refine or clarify a difficult clinical case. New MRI-generated hypotheses about the pathogenesis of diabetic retinopathy and its treatment are discussed. In the coming years, a substantial growth in the development and application of MRI is expected to address relevant question in both the basic sciences and in the clinic.

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