Drilling fluid processing: preparation, maintenance and continuous conditioning
The following discussion is an overview of the operation of drilling fluids at the rig site, giving an insight to those less versed in the art of drilling oil and gas wells. Fluid processing at the rig site is currently a prime target for higher levels of mechanization and process control, leading towards automation. The drilling fluids' composition influences its properties and dynamic behaviour, and the various drilling fluid components and additives all have specific purposes related to the drilling process. The process of drilling fluid preparation and mixing on the drilling rig is described, and the means of maintaining suitable properties during the drilling process are discussed. Means and requirements are presented for enabling continuous conditioning of the drilling fluid to suit the variations in the wellbore and formation, pointing out current challenges in measurement, instrumentation, mechanization, and control that need to be solved. It is clear that a higher level of automation is required if we wish to achieve this goal.
Automatic Measurement of Drilling Fluid and Drill Cuttings Properties
Abstract In order to remotely control the drilling process it is necessary to measure several drilling fluid parameters automatically. This will increase objectivity of the measurements as well as make it possible to immediately react to changes. The current paper describes in detail the design for an integrated tool combination and the results of a full size yard test of such a combined s et of tools for measuring drilling fluid parameters and formation properties automatically. Some of the automated tools have been tested on rig site operations. Results from these individual tests are also presented. The automatic drilling fluid analysis includes viscosity, fluid loss, electric stability measurements and chemical properties like pH. Full viscosity curves for the drilling fluid are measured using configurations and shear rates similar to those suggested by API procedures. Since gel formation curves and fluid loss properties require some sort of controlled static periods, these measurements are made semi-continuous. However, they are automatic and are measured as frequently as possible. An automatic system is included to measure the particle size distribution, concentration and morphology. Knowledge of these parameters is necessary, especially when drilling in depleted reservoirs where particles are added for increasing the wellbore strength. The produced cuttings volume is measured. An automatic system is adapted that determines, with accuracy comparable to that of visual analysis, whether the particles separated at the shaker screens are drill cuttings or cavings produced by an unstable formation. The mineralogy of the cuttings is analysed automatically using Raman spectroscopy, making it possible to evaluate continuously the different formations being drilled.
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.