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.
Analysis of the Ionospheric Effect for Time Offsets per GPS Code Measurements
This paper shows the analysis results of time offsets using P1, P2 and P3 code in GPS time transfer. The r2cggtts program has been used in GNSS Time Transfer and use the P3 ionosphere free combination of P1 and P2 code measurements. We modified the r2cggtts program in order to calculate and write all kinds of time offsets P3 as well as P1 and P2. The result of the modified r2cggtts program shows that time offsets using P1 and P2 are of wide distribution comparing to time offsets using P3. In order to Figure out the error factors for wide distributions of P1 and P2, we analyze and present the relation between the elevation angle and time offsets in this paper.