Pressure Drop in Tool Joints for the Flow of Water-Based Muds in Oil Well Drilling (original) (raw)
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MASTER'S THESIS CFD Modeling of Mud Flow around Drill Bit
This project was performed on behalf of SINTEF Materials and Chemistry in close collaboration with Lyng Drilling, part of the Schlumberger Group. The scope of the project has been to develop a method for geometry and setup simplifications on a Computational Fluid Dynamics (CFD) simulation made on a drill bit at work; to see if there is a possibility to implement this type of simulations as a step in the product development process of drill bits at the company Lyng Drilling. This in order to establish the local flow-patterns around the drill bit, that governs among other things how the cuttings is transported away and the cooling of the drill bit. The drill bits often have a pattern of surface erosion, caused by an increased intensity and velocity of the flow at that area. Zones with low flow velocity, stagnation points, can cause problems to the drilling as cuttings and mud can get stuck there subsequently leading to clogging of the drill head and increased energy required for the overall drilling. The only success on simulating the mud flow around the drill bit was obtained with transient simulations on a stationary drill bit. A rotating case was simulated with dynamic mesh, but simulation time was estimated to exceed 6 months, and this scenario was one of the limitations set initially in the project. No industrial gain can be obtained by implementing CFD-simulations as a step in the product development process for the design of drill bits at Lyng Drilling. The simulations are far too complex and require a lot of work and simulation time, as well as the parameter assumptions are too many.
Numerical study of drilling fluids pressure drop in wellbores with pipe rotation
IOP Conference Series: Materials Science and Engineering, 2019
Determining of the pressure loss is very complicated task in the petroleum drilling industry. In the present study the effect of different drilling muds flowing inside rotating pipe and exist from an annuals investigated. The effect of rotating speed and inlet speed. The flow is turbulent, steady and 3D with non-Newtonian fluid. The governing equations (continuity and momentum) are solved numerically using CFD with fluent soft package. The results are presented as : stream line, contours, pressure drop and wall shear stress. The results show that pressure drop is decreased when pipe rotational speed increase. slight increasing in shear stress at pipe rotating speed less than 200 rpm for same inlet velocity. Moreover, remarkable shear stress increasing can be observed as the rotational speed equal to or higher than 200 rpm.
Introducing a Rheology Model for Non-Newtonian Drilling Fluids
Geofluids
An API standard drilling fluid was investigated from laminar to turbulent flow conditions using an in-house-built viscometer at speeds from 200 to 1600 RPM. A power-based method was applied to obtain the apparent viscosity and the shear stress of the water-based drilling mud (WBM) in the annulus of the viscometer. Then, a MATLAB optimization program was developed to obtain model parameters for five rheology models integrated in a generalized Herschel-Bulkley-Extended (HBE) model and two widely used 4-parameter models in drilling industry. It is found that the Bingham, Cross, and HBE rheology models have precisely matched the WBM measurements in the viscometer. A generalized Reynolds number was applied to determine the Darcy friction factor although the PL (power law model) and the HB (Herschel-Bulkley model) exhibited a nonrealistic negative shift from the laminar friction factor.
Discovery Publication
"In rotary drilling, frictional pressure loss is an integral part of drilling hydraulic analysis as huge viscous forces are overcome in the drillstring and annulus, among others. However, these pressure losses mostly occur during mud circulation as a function of flow rate. Therefore, ascertaining the pressure dropflow rate profile of the drilling mud in drillstring and annulus is fundamental to optimizing pump power rating to avert longevity in the drilling operation. In this paper, the pressure drop-flow rate profile of some locally formulated drilling fluids: water-based and synthetic-based were evaluated in different flow regimes in drill pipe and annulus using Bingham plastic and Power law rheological models. The results obtained show that Power law model best described the rheology of the formulated synthetic-based drilling fluid. Additionally, the results further depict that with turbulent flow, Power law model results in high pressure loss when compared with Bingham plastic model in drill pipe and vice versa in the annulus. However, with laminar flow, the results indicate that Bingham plastic model results in high pressure drop when compared with Power law model both in drill pipe and annulus. Furthermore, the results depict that the pressure drop-flow rate profile of the formulated mud is in consonant with the correlations of the measured (experimental) and modeled rheological data of the formulated drilling fluids. Keyword: Pressure drop-flow rate profile, Rheological model, Drill pipe, Annulus, Flow regime."
A study of friction factor model for directional wells
Egyptian Journal of Petroleum, 2017
High torque and drag is one of the main problems in the directional wells. Friction models can be used for analysis during planning, drilling and after finishing the well. To have an accurate model it is very important to have the correct friction factor. This paper studies one of these models called Aadnoy's friction model. The purpose of this paper is to make an investigation on the limitations of the model, and also to find out how much the model can help for detecting the downhole problems. The author used an Aadnoy's based excel sheet done by TL Longbow Prime company for studying the model. The model has shown reliable results for slant wells which helped to estimate the downhole issue (Bitumen-high viscous oil). Also good torque results had been obtained for horizontal section despite the poor drag results. In the paper three different well profiles has been used during the study.
Simultaneous Continuous Monitoring of the Drilling-Fluid Friction Factor and Density
SPE Drilling & Completion, 2013
Summary This paper introduces a method to enable continuous automatic online updates of the density and frictional effects of the drilling fluid during drilling operations. The placement of differential-pressure sensors along the circulation path from the rig pump to the connection to the drillstring enables the fluid properties to be examined more thoroughly at various flow rates, pressures, and temperatures. The paper presents results from a full-scale test in which different fluids were examined. The results show that the method may give reliable data on the main drilling-fluid properties, which are important in all drilling operations, and especially in automatic modes.
AADE-12-FTCE-45 Mathematical Model for Pressure Transmission in Drilling Fluids
2012
This work puts forward a mathematical model for pressure transmission taking place in drilling fluids pressurized within closed drillpipe-wellbore geometries. The drilling fluid motion is considered as one-dimensional, isothermal and weakly compressible. The governing equations of continuity and momentum balance constitute the model and are solved iteratively by the method of characteristics. The drilling fluids are assumed to behave as Bingham fluids and the friction factor approach is used to account for the viscous effect. The results are validated against experimental data for water and two drilling fluids. Both the magnitudes and the oscillation frequencies of measured and computed values agree quite well for either water or the drilling fluids. In contrast with water, both measured and computed values of pressures for drilling fluids do not stabilize uniformly along the well after compression. In other words, pressure is not fully transmitted because of the strength of the yie...