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Significant variation in reserves during the life of a field from initial discovery through production and decline to abandonment, has long been recognized as a fact of life in the oil industry. As a fundamental asset of an oil company, there is a global desire to limit inaccuracies and present not only a consistent, but also an accurate view of reserves. Discussed here are the stages of a field's development and how these relate to reserves growth and decline. The impossibility of exact prediction from an inaccurate science in a changing world is acknowledged. Statistical information gathered on British Petroleum's fields has been analysed to illustrate historical movement and trends in reserves. The application and effect of recent advances in the techniques used in reservoir appraisal and reserves estimation is briefly reviewed.

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Background: Bivalirudin(B) and heparin(H) are the most common drugs used to prevent acute stent thrombosis during drug-eluting stent (DES) deployment. Prior studies comparing B to H with a IIB/IIIA agent have shown similar rates of stent thrombosis but decreased bleeding and mortality with B. With improved stent design, routine post-stent high pressure balloon inflation and IVUS guided therapy, acute complications of stent procedures other than bleeding have been reduced. We examined whether heparin given without a IIB/IIIA agent and bivalrudin would have similar rates of major adverse cardiac events (MACE) with DES. Methods: DES implants performed between 01/01/2007 and 01/01/2012 at St. Francis Hospital were reviewed using data reported to the New York State Department of Health. Clinical presentations, in-hospital and 30 day mortality, in hospital stent thrombosis and transfusion were assessed. Due to data element limitations and lags in Social Security Death Index reporting, full clinical presentation data and 30 day vital status were available in 76% and 77.9% respectively. Results: In 10,486 DES implantations a bolus of 7000U heparin(H, 5525) alone or a bolus and/or infusion of bivalrudin(B, 4875) was administered. Overall in-hospital mortality was 0.38%(H) versus 0.41%(B) pϭ0.55 and 30 day mortality was 0.76%(H) versus 0.81%(B), pϭ0.77. However in a very small subset with a diagnosis of acute myocardial infarction(AMI) mortality was increased on H(B 1.3%,nϭ233, vs H 7.0%, nϭ133, pϭ0.0036). Inpatient stent thrombosis was present in 0.09% on B compared to 0.08%on H, pϭ0.90, while 3.0% of patients on B required transfusion as compared to 2.9% on H, pϭ0.65. The frequency of all ACS at presentation was similar for H(93.6%) and B (93.2.%)(pϭ0.54). Conclusions:In patients undergoing DES implantation, bivalirudin reduced mortality only in patients with acute myocardial infarction. There were no differences in MACE between patients receiving bivalirudin and those receiving heparin without a IIB/IIIA inhibitor if AMI was absent. Given the marked cost differential between these agents, further studies to confirm our results in non-AMI patients would be appropriate.Background: Bivalirudin is increasingly the anticoagulant of choice for PCI.The degree of anticoagulation with direct thrombin inhibtors(DTI)has been measured with activated clotting time (ACT).This is hampered by the absence of a linear dose-response.Ecarin clotting time(ECT) however,has a linear dose response over a wide range of DTI concentrations.We aim to assess the correlation of both ACT and a point-of-care ECT assay with bivalirudin concentrations in an elective PCI patient population. Methods: A multi-center study of 150 patients undergoing elective coronary intervention with bivalirudin anticoagulation was performed.Citrated ECT,ACT,and anti-factor IIa activity were measured at baseline,10 minutes after bivalirudin bolus,and at the end of the procedure,producing 450 individual ECT,ACT,and anti factor IIa assays.Correlation and linear regression an...

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