Financial risk in health purchasing: risk pools
Part one of this series explored the financial risk associated with the size of a practice-based commissioning (PBC) group. A process for determining the point of minimum possible financial risk was illustrated by excluding high cost admissions from the core PBC budget (Jones, 2008). By implication, such exclusions will be gathered into a risk pool held on behalf of the PBC group.
Time to re-evaluate financial risk in GP commissioning
Financial risk is the gap between the available funds and the healthcare costs (activity and case mix) incurred by the population. Costs are subject to both statistical and environmental volatility. This article demonstrates that the combined and interactive effects of the wider environment leads to very high volatility in year-to-year costs and also generates a set of poorly-understood long-term cycles in healthcare demand leading to prolonged periods of above-average cost. It suggests that there are genuine sources of risk over which there is little direct control and that funding may need to follow a more flexible trajectory. What is called the ‘post code lottery’ arises out of the mismatch between the capitation formula and the susceptibility of local costs to volatility due to the environment.
Prevention of Barite Sag in Oil-Based Drilling Fluids Using a Mixture of Barite and Ilmenite as Weighting Material
Drilling high-pressure high-temperature (HPHT) wells requires a special fluid formulation that is capable of controlling the high pressure and is stable under the high downhole temperature. Barite-weighted fluids are common for such purpose because of the good properties of barite, its low cost, and its availability. However, solids settlement is a major problem encountered with this type of fluids, especially at elevated downhole temperatures. This phenomenon is known as barite sag, and it is encountered in vertical and directional wells under static or dynamic conditions leading to serious well control issues. This study aims to evaluate the use of barite-ilmenite mixture as a weighting agent to prevent solids sag in oil-based muds at elevated temperatures. Sag test was conducted under static conditions (vertical and inclined) at 350 °F and under dynamic conditions at 120 °F to determine the optimum ilmenite concentration. Afterward, a complete evaluation of the drilling fluid was performed by monitoring density, electrical stability, rheological and viscoelastic properties, and filtration performance to study the impact of adding ilmenite on drilling fluid performance. The results of this study showed that adding ilmenite reduces sag tendency, and only 40 wt.% ilmenite (from the total weighting material) was adequate to eliminate barite sag under both static and dynamic conditions with a sag factor of around 0.51. Adding ilmenite enhanced the rheological and viscoelastic properties and the suspension of solid particles in the drilling fluid, which confirmed sag test results. Adding ilmenite slightly increased the density of the drilling fluid, with a slight decrease in the electrical stability within the acceptable range of field applications. Moreover, a minor improvement in the filtration performance of the drilling fluid and filter cake sealing properties was observed with the combined weighting agent. The findings of this study provide a practical solution to the barite sag issue in oil-based fluids using a combination of barite and ilmenite powder as a weighting agent to drill HPHT oil and gas wells safely and efficiently with such type of fluids.