TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractDrilling depleted reservoirs is fraught with a host of technical and economic problems that often make it unprofitable to further develop some mature fields. Most of the problems center around uncontrollable losses in the large fractures that commonly characterize these reservoirs. Frequently, less expensive drilling fluids will be used in a particular interval, even though it may have the propensity to damage the formation. The reasoning holds that such fluids will offset the high costs of losing more expensive muds to the formation.A specialized invasion control drilling fluid has been developed to drill reservoirs prone to lost circulation. This fluid combines certain surfactants and polymers to create a system of "micro-bubbles" known as aphrons that are encapsulated in a uniquely viscosified system. These aphrons are non-coalescing, thereby creating a micro-bubble network for stopping or slowing the entry of fluids into the formation. The unique viscosity builds to create a resistance to movement into and through the zone, thus generating a true non-invasive and at-balance fluid. Test data confirms its enhanced hole cleaning and suspension properties. This paper describes the development and application of the specialized "micro-bubbles"-base drilling fluid for controlling downhole mud loss and formation damage. The authors will detail the laboratory methods used to generate appropriate formulations, the operational procedures, and field applications.As detailed in the paper, this novel drilling fluid relies entirely on "micro-bubbles" network bridging and does not contain any conventional particulate agent for sealing the loss zone. Therefore, the fluid can be pumped through narrow drill pipe, coil tubing and downhole tools. Case histories show that drilling problems are reduced, while drilling fluid losses are prevented or minimized dramatically.

Computational fluid dynamics (CFD) was used to simulate air flow changes in reconstructed nasal passages based on magnetic resonance imaging (MRI) data from a previous clinical study of 0.05% Oxymetazoline (Vicks Sinex Micromist®). Total-pressure boundary conditions were uniquely applied to accommodate low patency subjects. Net nasal resistance, the primary simulation outcome, was determined using a parallel-circuit analogy and compared across treatments. Relative risk (RR) calculations show that for a 50% reduction in nasal resistance, subjects treated with Sinex® are 9.1 times more likely to achieve this after 8 hr, and 3.2 times more likely after 12 hr compared to Sham.

Vibration Assisted Nano Impact-machining by Loose Abrasives (VANILA) is a novel nanomachining process that combines the principles of vibration-assisted abrasive machining and tip-based nanomachining has been developed by the authors to perform target specific nano abrasive machining of hard and brittle materials. One of the critical factors in achieving nanoscale precision during the VANILA process is to maintain an optimal machining gap between the tool and the workpiece surface. Piezoelectric crystal based positioning systems is a proven method for achieving ultraprecision control, however the application of such a system for controlling the nanoscale machining gap during a machining process is not explored. In this paper, the possibility of using a piezoelectric crystal based nano positioning setup to achieve the desired gap during the VANILA process is explored. This research thus finds a new application for the nanopositioning systems in order enhance the capability of existing VANILA process. Analytical models based on piezoelectric theory are done to predict the vibrational behavior of the piezoelectric crystal in the nano-positioning setup under different machining conditions. Further experiments are conducted to validate the model and study the mass-loading effect on the piezoelectric crystal. The model developed is agreeing within 20% with the experimentally determined values and thus the model forms the basis for using the nano-positioning system for maintaining optimal gap between the tool tip and the workpiece surface.