Advances in Drilling Fluid Preparation and Conditioning at Fluid Mixing Facilities
This paper will discuss liquid mud plant operations in conjunction with field integration of high-shear mixing, machinery limitations and performance data. The effects of high-shear mixing on fluid properties will be presented. Offshore operations and, in particular deepwater projects, depend on drilling fluids supplied by a liquid mud plant (LMP). Land-based LMPs are able to provide high volumes of fluids and other chemicals needed for deepwater drilling and completion. Moreover, LMP facilities are needed to prepare specialized and complex drilling fluids that meet or exceed design parameters, quality and environmental compliance. Drilling fluids chemistry and orderly preparation are essential for creating a quality fluid. The final product is affected by a wide variety of factors such as drilling fluid additive type and concentration, volumes mixed, the environment in which the fluid was prepared, the sequence of chemical addition and the type of equipment used for mixing. From a process-engineering perspective, mud preparation is a process where the chemical and physical reactions and interactions are optimized by additions of required ingredients and applications of appropriate equipment in a timely and sequential manner. In terms of process parameters, drilling fluid preparation mainly includes the influences of mixing energy inputs and conditions of temperature and pressure. High-temperature and pressure conditions are extremely challenging to reach at a mud plant or during mud mixing on a rig. However, high mixing energy input can be achieved by the use of high-shear mixers.
AADE 2009-NTCE-08-02: ADVANCES IN MIXING TECHNOLOGY IMPROVE DRILLING FLUID PREPARATION AND PROPERTIES
Industry has long recognized the importance of providing high-quality fluids for drilling, completion and production operations. With continuous developments of oilfield chemistry, these fluids have become increasingly complex and many of the chemical additives are hard to disperse or emulsify in solution. Traditional mixing techniques, such as circulating the fluid through jet nozzles or impellers, are becoming less satisfactory in achieving the desired properties for polymer-based drilling fluids. The mixing techniques used today are required to better disperse the chemical additives, but be gentle enough to preserve their long polymer chains and chemical structure. The mixing process and apparatus needs to be easily utilized at both onshore fluid mixing plants and at the rig-site. Both process and equipment must be economical, safe and environmentally responsible. Multifarious chemical processes and mechanical engineering evaluations have allowed the effects of high-shear mixing on water-, oil- and synthetic-based drilling fluid systems to be determined. In addition, laboratory studies have evaluated potential shear degradation of polyacrylic and xanthan polymer systems using several high-shear mixer designs. Through these studies, based on their superior technical performance and cost effectiveness, a multi-stage rotor-stator highshear mixer was selected as the most appropriate mixing apparatus to prepare drilling fluids. Full-scale testing proved these mixers to be effective and economically acceptable new solutions to drilling fluid preparation by alleviating problems of partially-dispersed or partiallyhydrated chemicals or poor emulsification. Because of low operating pressures, these units are considered safer than a high-pressure jet nozzle. The fluids prepared exhibited the required rheological properties through better chemical dispersion and produced stronger emulsions through the application of high shear, while remaining stable over longer periods. Performance data using single-stage and multi-stage mixers in the preparation of drilling fluids is discussed. Polymer degradation by high shear is confirmed and the data shows that using the proposed mixing devices provides sufficient energy for efficient mixing without polymer degradation. The use of multi-stage rotor-stator high-shear mixers is confirmed as a very powerful and beneficial tool to improve drilling fluid preparation.
Selective etching of InP in NaF solution
Abstract The crossing porous structure of InP has been obtained by electrochemical etching in NaF solutions. The behavior of the periodic oscillation occurs at different potential ranges for the different concentrations of solutions, and it will disappear with the concentration of the solution decreased. The scanning electron microscope (SEM) image shows that the pores have two directions on the surface and are perpendicular to each other. The two directions are assigned to [0 1 1] and [ 0 1 ¯ 1 ], respectively. The SEM image of the cross-section also shows that the two directions are assigned to [1 1 1]B and [ 1 1 ¯ 1 ¯ ]B. Both are due to the selective etching of F− ions. The crossing porous structure of InP is a very promising feature for the three-dimensional structure of III–V compound semiconductors for photonic band gap materials.