The behavior of smectic-A liquid crystals with magnetic particles has not been very well characterized. The authors have studied the interaction of a smectic-A liquid crystal with magnetic nanoparticles. They concentrate on the effect of the particles’ surface coating or functionalization compound. The surface coating in a nanoparticle is used to avoid phase separation and in biological applications to identify a particular cell or protein. Thus it is important to see how the surface coating interacts with the liquid crystal in conjunction with the magnetic nanoparticles. They have found out that depending on the surface coating the interaction of the nanoparticles with the liquid crystal varies. This variation is related to how the surface coating aligns the liquid crystal, how it contributes to the relative concentration of the nanoparticles in the liquid crystal-nanoparticle mixture, and how it affects the magnetic energy of the system.

The Turner model is widely used in industry to estimate critical gas velocity to flow a gas well and unload its liquid content under steady state conditions. The Zhou model introduced improvements to the Turner model by taking into account the influence of total Liquid (condensate and water) to Gas Ratio (LGR) on critical gas velocity. While fairly acceptable at low LGR, current models do not address the impact of liquid holdup on wellhead flowing conditions and subsequent changes in critical gas unloading rates. Multiphase modeling is used in this study to validate the applicability of current models at various wellbore conditions and LGR. This study finds important applications in offshore and onshore gas field developments because it provides moe reliable assessment especially for gas fields in the depletion phase, or when liquid breakthrough occurs resulting in high LGR. Dynamic simulations indicate that at low to moderate LGR existing models under predict critical gas flowrate because they under estimate critical velocity, especially at high wellhead pressures, and don't take into account the impact of increasing liquid holdup on gas flowrate. Moreover, an inversion in critical flowrate occurs at very high LGR because the film holdup is sufficient to restrict the flow of gas and offsets any increase in critical velocity at such high LGR. The onset of liquid loading (well choking) is associated with the transition from annular to churn/slug flow. This is well demonstrated from the calculated trends of entrained droplet holdup. The significance of the current work to our understanding of critical flow in gas wells is illustrated by utilizing a multiphase simulator to better characterize the impact of entrained droplet and film holdup on critical flowrate and by predicting the inversion in critical gas flowrate at high LGR. The results of this study provide an enhanced understanding of well loading during all development phases and various production conditions to evaluate the applicability and accuracy of widely used models in a broad range of well conditions and liquid loads.

High Pressure / High Temperature (HP/HT) design of a flowline system has become a common design challenge as the quest to extract hydrocarbons has pushed the industry to exploit deeper reservoirs. In recent years, industry has classified systems over~10,000 psi and over~300°F as XHPHT (Extra HP/HT). As subsea technology continues to develop, it may not be farfetched to be soon considering UHPHT (Ultra HP/HT) flowline designs.This paper addresses the key features and challenges of the HP/HT design as applied to the production flowlines of a deepwater Miocene GoM (Gulf of Mexico) field. The dual production flowlines are each 10 miles long with SITP (Shut-In Tubing Pressure) of~15000-psi and maximum design temperature of 300°F (classified as XHPHT). HP/HT specific design challenges are associated with large expansion, global buckling, axial creep, and low-cycle fatigue, which are directly influenced by the flowline length. Even though the tie-back distance to the host is relatively long, the definition of "short" and "long" flowline/pipeline loses its significance due to distributed responses (both "Natural" and "Engineered") of system. Additionally, due to field-specific fluid properties, excessive pressure drops across the well perforation and / or the subsea choke can cause Joule-Thomson heating effects, which must be accounted for in design. This paper further discusses optimization of various design components in order to accommodate small variations in the input parameters (soil, operational transients, installation tolerances etc.) that are crucial with respect to global and local responses.This case study uses mitigation techniques at pre-determined locations to address the design concerns such as large expansions, rogue (uncontrolled) buckles, axial creep ("walking"), and low-cycle fatigue. By exercising careful review of the iterative assessments and subsequent optimization of the system's overall design, a safe and reliable solution is achieved. HP/HT design philosophy for deepwater Miocene GOM fields form an integral part of design / implementation processes in the field development program and have significant influence on the overall subsea architecture, procurement and construction strategy, operating philosophy, and integrity management plan. Finally, the paper shows a comparison of numerical prediction and the data acquired from the field observations. The predicted system response is in good agreement with the field observations, thereby, validating the overall assessment/modeling approach and confirming the robustness of the system's response.

We have observed the effects of adding magnetic nanoparticles with a different surface termination to smectic A 8CB liquid crystals by examining the liquid crystals by X-ray scattering. Adding the magnetic nanoparticles improves the liquid crystal's response to a magnetic field by at least one to two orders of magnitude. We have performed the experiments with four types of organic compounds covering the nanoparticles, using 11 nm and 2 nm FeCo nanoparticles, and have varied the applied magnetic field from 225 mT to 362 mT. There is a variation on the effect due to the size of the nanoparticles and also to the concentration of the particles in the mixture. As a function of magnetic field, the 11 nm and 2 nm particles terminated in polyethelyne glycol 3000 exhibit the largest rotation with the magnetic field. The liquid crystal rotates in opposite directions depending on the concentration of particles.