Detailed Modeling of Drilling Fluid Flow in a Wellbore Annulus While Drilling

2013 ◽  
Author(s):  
Evgeny Podryabinkin ◽  
Valery Rudyak ◽  
Andrey Gavrilov ◽  
Roland May
Keyword(s):  
Numerical Solutions ◽  
Drilling Fluid ◽  
Full Range ◽  
Newtonian Fluids ◽  
Rheological Parameters ◽  
Flow Mode ◽  
Drilling Fluids ◽  
New Model ◽  
Wellbore Pressure ◽  
Analytical Approaches

To produce a well safely, the wellbore pressure during drilling must be in a range that prevents collapse yet avoids fracturing. This range is often called “the operating window”. Exceeding the limits of this range can trigger wellbore instability or initiate well control incidents. Pressure prediction requires an understanding of the hydrodynamics processes that occur in a borehole while drilling. Describing these processes is complicated by many factors: the mud rheology is usually non-Newtonian, the flow mode can be laminar or turbulent, and the drillstring can rotate and be positioned eccentrically. Known semi-analytical approaches cannot account for the full range of fluid flows that can arise during drilling. These techniques don’t take into account all factors. Accurate numerical simulation of the flow of drilling fluids is a means to describe the fluid behavior in detail. For numerical solutions of hydrodynamics equations a unique algorithm based on a finite-volume method and a new model of turbulence for non-Newtonian fluids was developed. The model considers string rotation and eccentricity of the drillstring. Newtonian and non-Newtonian fluids as described by the Herschel–Bulkley rheological model have been implemented. Data obtained via systematic parameter studies of the flow in a borehole are available for fast determination of parameters like pressure drop, velocity field, and stresses corresponding to any drilling condition. Applying the new model for the annulus flow and comparing the results to the parallel plate flow approximation enabled us to quantify the error made due to the approximated solution for non-Newtonian fluid rheology. The difference between the solutions grows as the annular gap increases. This situation is a function of the rheological parameters. Secondary flow effects can only be seen when applying the new solution method.

A Semi-Analytical Model for Predicting Horizontal Well Performances in Fractured Gas Reservoirs With Bottom-Water and Different Fracture Intensities

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Yongsheng Tan ◽  
Haitao Li ◽  
Xiang Zhou ◽  
Beibei Jiang ◽  
Yongqing Wang ◽  
...  
Keyword(s):  
Porous Medium ◽  
Horizontal Well ◽  
Bottom Water ◽  
Flow Model ◽  
Numerical Solutions ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
New Model ◽  
Well Completion ◽  
Wellbore Pressure

Numerical simulation and prediction studies on horizontal well performances in gas reservoir are foundation for optimizing horizontal well completion process. To gain more understanding on this theory, a steady-state reservoir model coupling with wellbore is developed in the fractured gas reservoirs with bottom-water and different fracture intensities to predict the horizontal well performances. Based on the equivalent flow assumption, the fractured porous medium is transformed into anisotropic porous medium so that the gas reservoir flow model can be developed as a new model that incorporates formation permeability heterogeneity, reservoir anisotropy, and gas reservoir damage. The wellbore flow model which considers pressure drops in the tubing is applied. We compare this paper model solutions for inflow profile along the well to the numerical solutions obtained from a commercial simulator (ECLIPSE 2011), and the result shows a very good agreement. Moreover, sensitive analysis, in terms of various linear densities of fractures, matrix permeability, fracture width, and wellbore pressure drop, is implemented. The results show that the new model developed in this study can obtain a more practical representation to simulate the horizontal wells performance in fractured gas reservoir with different fracture intensities and bottom-water, thus can be used to optimize the parameters in horizontal well completion of fractured gas reservoirs with different fracture intensities and bottom-water.

New Model to Analyze Nonlinear Leak-Off Test Behavior

1999 ◽  
Vol 121 (2) ◽  
pp. 102-109 ◽  
Author(s):  
G. Altun ◽  
E. Shirman ◽  
J. P. Langlinais ◽  
A. T. Bourgoyne
Keyword(s):  
Mathematical Model ◽  
Drilling Fluid ◽  
Nonlinear Behavior ◽  
Injection Pressure ◽  
Maximum Pressure ◽  
Drilling Fluids ◽  
Total System ◽  
Verification Method ◽  
Fracture Pressure ◽  
Wellbore Pressure

A leak-off test (LOT) is a verification method to estimate fracture pressure of exposed formations. After cementing each casing string, LOT is run to verify that the casing, cement and formation below the casing seat can withstand the wellbore pressure required to drill for the next casing string safely. Estimated fracture pressure from the test is used as the maximum pressure that may be imposed on that formation. Critical drilling decisions for mud weights, casing setting depths, and well control techniques are based upon the result of a LOT. Although LOT is a simple and inexpensive test, its interpretation is not always easy, particularly in formations that give nonlinear relationships between pumped volume and injection pressure. The observed shape of the LOT is primarily controlled by the local stresses. However, there are other factors that can affect and distort LOT results. Physically the LOT, indeed, reflects the total system compressibility, i.e., the compressibility of the drilling fluid, wellbore expansion, or so-called borehole ballooning, and leak (filtration) of drilling fluids into the formation. There is, however, no mathematical model explaining the nonlinear behavior. Disagreement on determining or interpreting actual leak-off pressure from the test data among the operators is common. In this paper, a mathematical model using a well-known compressibility equation is derived for total system compressibility to fully analyze nonlinear LOT behavior. This model accurately predicts the observed nonlinear behavior in a field example. The model also predicts the fracture pressure of the formation without running a test until formation fracture.

A Wellbore Pressure Calculation Method Considering Gas Suspension in Wellbore Shut-In Condition

2021 ◽  
Author(s):  
Zhi Zhang ◽  
Baojiang Sun ◽  
Zhiyuan Wang ◽  
Shaowei Pan ◽  
Wenqiang Lou ◽  
...  
Keyword(s):  
Yield Stress ◽  
Calculation Method ◽  
Optimization Design ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Gas Suspension ◽  
Wellhead Pressure ◽  
Suspension Concentration ◽  
Wellbore Pressure

Abstract In the oil industry, the drilling fluid is yield stress fluid. The gas invading the wellbore during the drilling process is distributed in the wellbore in the form of bubbles. When the buoyancy of the bubble is less than the resistance of the yield stress, the bubble will be suspended in the drilling fluid, which will lead to wellbore pressure inaccurately predicting and overflow. In this paper, the prediction model of gas limit suspension concentration under different yield stresses of drilling fluids is obtained by experiments, and the calculation method of wellbore pressure considering the influence of gas suspension under shut-in conditions is established. Based on the calculation of the basic data of a case well, the distribution of gas in different yield stress drilling fluids and the influence of gas suspension on the wellbore pressure are analyzed. The results show that with the increase of yield stress, the volume of suspended single bubbles increases, the gas suspension concentration increases, and the height at which the gas can rise is reduced. When the yield stress of drilling fluid is 2 Pa, the increment of wellhead pressure decreases by 37.1% compared with that without considering gas suspension, and when the yield stress of drilling fluid is 10Pa, the increment of wellhead pressure can decrease by 78.6%, which shows that when the yield stress of drilling fluid is different, the final stable wellhead pressure is quite different. This is of great significance for the optimization design of field overflow and kill parameters, and for the accurate calculation of wellbore pressure by considering the suspension effect of drilling fluid on the invasion gas through the shut in wellhead pressure.

A New Device for Field Recovery of Barite From Drilling Mud: I. Theory and Laboratory Results

1965 ◽  
Vol 5 (01) ◽  
pp. 6-14 ◽  
Author(s):  
R.F. Burdyn
Keyword(s):  
Particle Size ◽  
Specific Gravity ◽  
Drilling Fluid ◽  
Outer Cylinder ◽  
Maximum Amount ◽  
Rheological Parameters ◽  
Drilling Fluids ◽  
Concentric Cylinder ◽  
Drilling Technology ◽  
Operating Equation

Abstract The inadequate use of centrifugation to economically recover solids from weighted drilling fluids reflects the need for better equipment and techniques for this purpose. Laboratory studies in the development of an improved separator are described in which an operating equation is derived and tested. Results show that the concentric cylinder geometry employed effectively separates barite from a suspension and that the operating equation provides a good approximation for scale-up. Introduction Our current drilling technology frequently requires a high-density drilling fluid obtained by addition of barite. In the course of drilling, formation solids which are too fine to be removed either by screening or settling become suspended in the drilling fluid and gradually the volume of solids in the mud increases. The volume fraction of solids must be limited (if a satisfactory set of rheological parameters are to be maintained). A centrifugal separator provides an economical way of accomplishing this. The barite recovery process can be considered as a separation of two solids. One, the light solids, composed of formation and added solids, has a specific gravity of 2.6 to 2.7; the other, barite, has a specific gravity of 4.2 to 4.3. This density difference, plus the fact that the average light-solids particle size is much smaller than the average barite particle size, permits separation by a centrifuge. In drilling fluids some of the coarse particles of the light-solids-range will settle faster than fine particles of the barite-particle range. As a result a complete separation of the two species is not possible. Since the object of the process is not merely recovering the maximum amount of barite but includes as well removing the maximum amount of light solids, an optimum barite recovery efficiency exists. From a practical standpoint this optimum cannot be determined in the field for each drilling fluid system, and in practice the separation is less than optimum, with some sacrifice of barite. Drilling technology has included centrifugal separators for barite recovery for more than a decade. Results have been reported by a number of investigators indicating that the process is practical and economical. The decision to use a centrifuge is based on economics in which direct cost savings and the indirect benefits in rig time derived from improvement of the drilling fluid are important factors. One would expect that centrifugal separation of barite from drilling fluids would significantly affect barite consumption; however, this is not the case. The Minerals Yearbook shows an annual domestic barite consumption in the drilling industry of nearly I million tons. By rough estimate there are perhaps 80 separators presently in field use. Assuming half of these in use at any one time, operating an, average of four hours per day, at recovery rates averaging 3,000 lb of barite per hour, total annual recovery is about 90,000 tons. This is less than 10 per cent of the total barite used. I conservatively estimate that barite consumption in drilling operations can be reduced by 30 per cent through greater utilization of centrifugal separators. To encourage more wide- spread acceptance of centrifugal separators in the drilling industry, improved equipment and techniques would be very desirable. The present paper, covering theory and results obtained from a laboratory model, is the first in a series on the development of an improved mud separator for field use. THE CONCENTRIC CYLINDER GEOMETRY AS A SEPARATING DEVICE Consider the geometry shown in Fig. 1, consisting of two concentric cylinders separated by an annular space. These are arranged so that the outer cylinder is fixed and the inner one can be rotated about its axis on shafts sealed against the ends of the outer cylinder. SPEJ P. 6ˆ

Evaluation of Equivalent Circulating Density in Deep Water Dynamic Kill Drilling

2011 ◽  
Vol 121-126 ◽  
pp. 3048-3052 ◽  
Author(s):  
Xiao Ling Jiang ◽  
Zong Ming Lei ◽  
Qing Bao Meng
Keyword(s):  
Low Temperature ◽  
Deep Water ◽  
Pressure Loss ◽  
Drilling Fluid ◽  
Rheological Parameters ◽  
Drilling Fluids ◽  
Normal Cycle ◽  
Shallow Wells ◽  
Water Surface Layer ◽  
The Impact

Dynamic kill drilling is a technology which is applied in order to control the deep water drilling shallow gas or shallow wells flowing by establish a normal cycle automatically in the deepwater shallow wells section. Equivalent circulating density (ECD) is an important parameters to control the bottom hole pressure, in the ECD estimate, if we don’t consider the effects of low temperature on rheological parameters of drilling fluid, it will result in errors in ECD estimates. Considering the impact of low temperature on the rheological parameters, this paper determines the temperature, rheological parameters and the annulus circulating pressure loss of each well section. Then Superposing each well section annular circulating pressure loss together, and finally calculate the equivalent circulating density. The deeper the water the greater of difference between ECD prediction model and the results calculated by rheological parameters on ground, and the more shallow wells the larger of difference. Therefore, in the process of deep water surface layer dynamic killing, We need to predict the equivalent circulating density of drilling fluids (ECD) accurately.

scholarly journals Investigation of Non-Linear Rheological Characteristics of Barite-Free Drilling Fluids

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 327
Author(s):  
Ekaterina Leusheva ◽  
Nataliia Brovkina ◽  
Valentin Morenov
Keyword(s):  
Oil And Gas ◽  
Drilling Fluid ◽  
Rheological Parameters ◽  
Drilling Fluids ◽  
Drilling Mud ◽  
Gas Wells ◽  
Oil And Gas Wells ◽  
Fluid Properties ◽  
Hydrolyzed Polyacrylamide ◽  
Drilling Muds

Drilling fluids play an important role in the construction of oil and gas wells. Furthermore, drilling of oil and gas wells at offshore fields is an even more complex task that requires application of specialized drilling muds, which are non-Newtonian and complex fluids. With regard to fluid properties, it is necessary to manage the equivalent circulation density because its high values can lead to fracture in the formation, loss of circulation and wellbore instability. Thus, rheology of the used drilling mud has a significant impact on the equivalent circulation density. The aim of the present research is to develop compositions of drilling muds with a low solids load based on salts of formate acid and improve their rheological parameters for wells with a narrow drilling fluid density range. Partially hydrolyzed polyacrylamide of different molecular weights was proposed as a replacement for hydrolized polyacrylamide. The experiment was conducted on a Fann rotary viscometer. The article presents experimentally obtained data of indicators such as plastic viscosity, yield point, nonlinearity index and consistency coefficient. Experimental data were analyzed by the method of approximation. Analysis is performed in order to determine the most suitable rheological model, which describes the investigated fluids’ flow with the least error.

scholarly journals Research of Bare-Free Drilling Fluids

2021 ◽  
Vol 21 (3) ◽  
pp. 123-130
Author(s):  
Ekaterina L. Leusheva ◽  
Nazim T. Alikhanov
Keyword(s):  
Drilling Fluid ◽  
Inhibitory Effect ◽  
Rheological Parameters ◽  
Fluid Loss ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Geological Conditions ◽  
Water Based ◽  
Environmental Requirements ◽  
The Stability

Mining and geological conditions for the development of new fields are becoming more difficult every year. Accordingly, the requirements for ensuring the environmental and technological safety of the drilling process are becoming more and more important. To ensure such a process, it is necessary to use correctly selected drilling fluids with proper characteristics: rheological parameters sufficient for effective cleaning of the well bottom, density sufficient to create back pressure, fluid loss to ensure a high-quality filter cake. Modern environmental requirements dictate the abandonment of hydrocarbon-based solutions. But when using water-based solutions, there are no suitable solutions, especially with their high density, since the use of barite can lead to a decrease in reservoir productivity. In this regard, the analysis of the problem and the search for options for creating water-based drilling fluids, weighted without the addition of barite, having the properties of maintaining the stability of the wellbore, ensuring safe drilling and opening productive formations without damaging the reservoir characteristics, was carried out. Such a solution was found in changing the base of the drilling fluid - highly mineralized fluids or solutions based on saturated brines. Brines must be created on the basis of inorganic salts that have good solubility, for example, chlorides, bromides. Due to the content of salts, the fluids have an inhibitory effect, and depending on the volume of dissolution, the density of the drilling fluids can be controlled. The scientific works of foreign and domestic scientists analyzed in the article have been published over the past five years, which indicates the relevance of this development. The selected compositions are presented and theoretically investigated, which were also tested in the field conditions.

scholarly journals Influence of Polymer Reagents in the Drilling Fluids on the Efficiency of Deviated and Horizontal Wells Drilling

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4704
Author(s):  
Tianle Liu ◽  
Ekaterina Leusheva ◽  
Valentin Morenov ◽  
Lixia Li ◽  
Guosheng Jiang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Shear Stress ◽  
High Molecular Weight ◽  
Drilling Fluid ◽  
Horizontal Wells ◽  
Rheological Parameters ◽  
Drilling Fluids ◽  
Dynamic Shear ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer

Improving the efficiency of well drilling process in a reservoir is directly related to subsequent well flow rates. Drilling of deviated and horizontal wells is often accompanied by an increase in pressure losses due to flow resistance caused by small size of the annular space. An important role in such conditions is played by the quality of borehole cleaning and transport capacity of drilling fluid, which is directly related to the rheological parameters of the drilling fluid. The main viscosifiers in modern drilling fluids are polymer reagents. They can be of various origin and structure, which determines their features. This work presents investigations that assess the effect of various polymers on the rheological parameters of drilling fluids. Obtained data are evaluated taking into account the main rheological models of fluid flow. However, process of fluid motion during drilling cannot be described by only one flow model. Paper shows experimentally obtained data of such indicators as plastic viscosity, dynamic shear stress, non-linearity index and consistency coefficient. Study has shown that high molecular weight polymer reagents (e.g., xanthan gum) can give drilling fluid more pronounced pseudoplastic properties, and combining them with a linear high molecular weight polymer (e.g., polyacrylamide) can reduce the value of the dynamic shear stress. Results of the work show the necessity of using combinations of different types of polymer reagents, which can lead to a synergetic effect. In addition to assessing the effect of various polymer reagents, the paper presents study on the development of a drilling fluid composition for specific conditions of an oil field.

scholarly journals Numerical study of cutting transport using aerated drilling fluids

2021 ◽  
Vol 2119 (1) ◽  
pp. 012051
Author(s):  
V A Zhigarev ◽  
S O Zazulya ◽  
A V Minakov ◽  
A L Neverov
Keyword(s):  
Fluid Flow ◽  
Horizontal Well ◽  
Numerical Study ◽  
Drilling Fluid ◽  
Rheological Parameters ◽  
Drilling Fluids ◽  
Cuttings Transport ◽  
Foaming Agent ◽  
Water Based ◽  
Drill Pipes

Abstract The paper deals with drilling fluid flow in a horizontal well during its drilling. As part of this work, rheological parameters of water-based drilling fluid with the addition of polymers and a foaming agent were used. Cuttings transport was studied at different degrees of foam aeration. Besides, the paper presents the study of the effects of drilling fluid flow, as well as the rotation of drill pipes on the cuttings transport.

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