SPE Dynamic Filtration of Bentonite Muds Under Different Flow Conditions (original) (raw)
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SPE 128035 A Theoretical and Experimental Analysis of Dynamic Filtration in Drilling Operations
This paper describes a numerical filtration model validated by data obtained from an experimental dynamic filtration loop. The model predicts the filtercake buildup and filtrate flow rate in the drilling process using non-Newtonian muds. It is also able to calculate filtercake properties like permeability and thickness. The equations, written in cylindrical coordinate, are based on the motion and mass conservation equation of the fluid described by Darcy's law. In addition, the permeability and porosity are correlated to the filtercake pressure. The point at which the mud fluid shear rate and the filtercake shear strength are equal defines the filtercake thickness. In the dynamic filtration loop there is a tube with a permeable wall where the carbonate suspension of different sized particles is filtrated. The suspension is homogenized in a tank mixer and pumped using a positive displacement pump. The filtration model was validated through experimental data. In this paper, we discuss the effects of cross-flow velocity and filtration pressure on the filtrate rate and filtercake buildup. The simulated data of filtrate rate and filtercake thickness agreed well with the experimental data. Introduction One of the drilling fluid's basic functions is to exert hydrostatic pressure over the permeable formations to avoid the formation fluid invasion to the well while the drilling operation takes place. The fluid pressure is normally kept above the formation pore pressure to prevent from kick events (formation fluid invasion to the well), that, in some cases, can lead to an uncontrolled influx (blowout). This concept, called overbalanced drilling, is traditionally employed in most of the drilling operations worldwide and in Brazil. As the bit penetrates the reservoir rock, the drilling fluid invades the formation due to the positive pressure differential between the well and the reservoir rock. Portions of the liquid phase of the drilling fluid are lost to the adjacent formation while part of the solids presented in drilling fluid, constituted by particles smaller than the formation pore size, penetrate the rock during the fluid loss period, rapidly plugging the region around the well. Larger particles accumulate on the wellbore walls, initiating an external cake formation. The invasion of fluid and solid particles during this process causes damage to formation around the well. Two invasion mechanisms are notable in the well. The first, called static filtration, occurs when the fluid pumping is interrupted and, from that point on, filtration occurs due to the difference between the hydrostatic pressure in the well and the reservoir pressure. The filtration rates are controlled by the continuously increasing thickness of the filter cake. The other invasion mechanism, called dynamic filtration, occurs when the fluid is pumped through the well. In this process, the cake thickness is resultant from the dynamic equilibrium between solid particles deposition rate and the erosion rate due to the shear stresses generated by the fluid flow in the wellbore. Thus, the filtration rate to the formation tends to stabilize around a certain value while the cake thickness turns constant. Fig.1 illustrates the process. Table 1 shows several authors that studied dynamic and static filtration phenomenon. Modeling and experimental work are listed.
Dynamic filtration of drilling fluids and fluid loss under axially rotating crossflow filtration
Journal of Petroleum Science and Engineering, 2018
The filtration characteristics of drilling fluids were evaluated by dynamic filtration under cross flow geometry. Crossflow (tangential flow) filtration by using a rotating cylinder geometry occurs when the mud is being circulated radially by inner rotating cylinder and permeates tangentially through the outer wall filter media. Dynamic filtration tests under cross flow represent more realistic conditions compared to static tests. The growth of the filter cake and filtrate flow are controlled by the blocking and erosive action of the mud stream. Dynamic HPHT ® Filtration System Model 90 which operates at high temperature and high pressure, manufactured by Fann Instrument Company™ is the most commonly used device to evaluate fluid loss and filtration characteristics of drilling fluids. However, according to its equipment manual, there are no standard methods for interpreting the dynamic filtration data. Here, the fluid loss data of drilling mud formulations were modelled based on the kinetics of filtration and plugging of through filtration media by drilling muds. The total volume loss, V as a function of
Analysis of Dynamic and Static Filtration and Determination of Mud Cake Parameters
Brazilian Journal of Petroleum and Gas, 2011
Drilling operations around the world employ a concept called overbalance. During this process, it is well known that dynamic and static filtration can occur. Thin filter cakes and low fluid-invasion rates are extremely desirable to promote optimal logging conditions and permeability return. The aim of this work was to compare the different behavior between dynamic and static filtration in drilling wells. To investigate the filtration process of Newtonian suspensions, we built a dynamic and static filtration loop with which we acquired experimental filtration volume data as a function of time. The filtration loop included a tank mixer where a Newtonian aqueous calcium carbonate polydisperse suspension was homogenized. The suspension was pumped through tubes to a dynamic or a static filtration cell. We validated a theoretical model based on Darcy's law and on mass conservation proposed by . That model predicted mud cake buildup and filtrate flow rate for Newtonian suspensions. Relying on both models and the experimental data, filter cake parameters were calculated. We discuss, based on these parameters, the effects of the filtration configuration in dynamic and static modes. Finally, we generalized Ferreira and Massarani's model (2005) for procedures involving non-Newtonian suspensions. This new model can predict dynamic filtration and fluid invasion for non-Newtonian suspensions as drilling fluids. KEYWORDS dynamic and static filtration; Newtonian and non-Newtonian fluids; fluid invasion; mud cake buildup; drilling mud
Filtration is used in many industries to separate water from the solid. It is important to find fluid loss in drilling, cementing, fracturing, and almost every other type of downhole treatment design. The filter cake characterization is very essential for well selection of drilling fluid problems and formation damage. Therefore this study is taken up to experimentally investigate the effect of different concentrations of CMC, Starch, Wood fibers, Soda ash, Caustic soda, Bentonite and Barite on filtration loss and formation damages. Three different samples are used in this study at different concentration and a comparison is made. Although the discussion presented here is confined to fluid loss during drilling. Water-based drilling mud's including Bentonite is well-known and is being widely used in the petroleum industry. Among the important functions of water-based drilling fluid were to form filter cake on the wall of the well bore, prevent water leakage, and maintain the stability of the well wall. The properties of the water-based drilling fluid, such as the rheology and filtration loss, are affected by the fluid loss additive. Polymers, which are nontoxic, degradable, and environment friendly, are the best choice to be used as drilling fluids additives.
Rock Mechanics and Rock Engineering
Drilling mud filtration occurs during an overbalanced drilling activity and concurrently with mud loss through pore throats and fractures. Mud loss and filtration are increased when the wellbore fluid condition is in a dynamic mode (pipe rotation and/or fluid circulation), rather than static. Formation damage is a critical industry challenge that results from mud loss and filtration. There is a considerable amount of experimental studies with only a few modeling approaches for characterizing dynamic mud filtration. Most of these studies have not accounted for factors that can exacerbate mud filtration which includes but not limited to: temperature, pipe rotation, pip/wellbore geometry/eccentricity, and porous media complexity. In this study, two mathematical and computational modeling approaches that can be used to predict dynamic drilling mud filtration in a radial coordinate system are presented. In the first modeling approach, a mechanistic model that is based on a material balance of filter cake evolution is presented. Critical factors that impact dynamic-radial mud filtration (temperature, rotary speed, rock permeability, and rock porosity) and other factors (wellbore/reservoir dimensions, filter cake properties, and mud/ filtrate rheological properties at reservoir temperature) were accounted for. The model was solved with a numerical approach and commercial software. In the second approach, a scanning electron microscopy image of selected dry core samples, combined with image processing, was used to estimate the pore size and porosity of the internal filter cake. The pore structure of the rock samples and filter cake was modeled using the bundle of curved tubes approach. The deposition probability of mud particles was considered through filtration theories. The modeling results were validated with dynamic-radial filtration experiments. The results from both models closely matched the experimental results. On average, the models revealed no more than 4% relative error in predicting dynamic mud filtration. The novelty in both approaches is the incorporation of critical parameters in the models over a wide range and their responses to cumulative filtrate invasion in different rock types. Keywords Dynamic-radial • Mud filtration • Modeling • Permeability • Filter cake List of Symbols c p Mass of particles per unit volume of carrier fluid in slurry (g/cm 3 mud) h Height of formation/cake height (cm) K Permeability K f Formation permeability (Darcy) K c External mud cake permeability (Darcy) k Consistency index (dynes/cm 2 /s n′) k d Deposition coefficient (dimensionless) k e Erosion coefficient (s/cm) L Length of the porous media n Flow behavior index (dimensionless) P Trapping probability of particles
An overview on mud filtration in oil wells and its relations
4th international conference on recent innovations in chemistry & chemical engineering,Iran,Tehran, At Tehran, 2017
Usually in an under-balanced drilling operation, due to pressure difference between mud and formation, amount of drilling mud enters the porous media or high permeable formation and reduces permeability around well bore which is a kind of formation damage. This phenomenon is called drilling mud filtration. In some cases, extreme mud filtration may cause lose circulation which is a dramatic damage. Filtration controlling and keeping it in optimized situation to avoid lose circulation is required to have a successful drilling process. In this research, fundamental concepts of filtration, affecting factors on filtration, methods and relation for measuring filtration and its simulation is discussed.
A new model for curbing filtrate loss in dynamic application of nano-treated aqueous mud systems
2020
Filter cake formation during rotary drilling operation is an unavoidable scenario, hence there is need for constant improvement in the approaches used in monitoring the cake thickness growth in order to prevent drill-string sticking. This study proposes an improved model that predicts the growth of mud cake thickness overtime with the consideration of the addition of nanoparticles in the formulated drilling fluid system. Ferric oxide, titanium dioxide and copper oxide nanoparticles were used in varying amounts (2 g, 4 g and 6 g), and filtration data were obtained from the HPHT filtration test. The filter cakes formed were further analyzed with scanning electron microscope to obtain the morphological characteristics. The data obtained was used to validate the new filtrate loss model. This model specifically presents the concept of time variation in filter cake formation as against the previous works of constant and definite time. Regression coefficient which is a statistical measure ...
2018
I would like to express my deepest gratitude to God Almighty for granting me life and good health of mind and body to complete this PhD program. My profound gratitude and appreciation go to my dissertation direction: Dr. Saeed Salehi (PhD P.E). He took me under his supervision from my first day in graduate school (January 14, 2013), trained me, sponsored me, and put me through hard and smart work. In my toughest times, he was there to lift me up. Dr. Salehi exposed me to several research projects, mentored me to publish 24 papers from my research area and supported me in making over 20 technical presentations at local, national, and international conferences, symposiums, and meetings. Dr. Salehi, I will be forever indebted to you. Thank you very much for everything. I would like to thank all the members of my dissertation committee for accepting to be in the committee and their time. Beginning with the outside committee member, Dr. Ziho Kang (PhD), your feedbacks on my statistical design and analysis were very useful. Special thanks go to Dr. Ramadan Ahmed (PhD), Dr. Cataline Teodoriu (PhD), and Dr. Mashhad Fahes. The contributions and feedbacks you all gave during my research, particularly during my general exam were extremely valuable. It was an honor to have worked closely with Mr. Jeff McCaskill at the OU Well Construction and Technology Center (WCTC). You were my go-to personnel during my experiments, especially when the machines broke down and/or a process needs to be adjusted or improved in the lab. Thank you. My gratitude goes to Dr. Carl Sondergeld (PhD) for permitting me to conduct my rock properties measurements, scanning electron microscope imaging, and elemental mapping at the Integrated Core Characterization Center (IC 3). In addition, I am grateful vi to Dr. Mark Cutis (PhD), Dr. Ali Tinni (PhD), and Mr. Gary Stowe for their support during my investigations at the IC 3. I am also grateful to the Mewbourne School of Petroleum and Geological Engineering for granting me scholarships and travel awards to support my studies and research presentations. This acknowledgement is incomplete if I do not recognize Dr. Raj Kiran (PhD). We started this journey together and he provided valuable analytical contributions to my research. I am very grateful. Special mention goes to my friends who played different roles during this period of my
The Use of Periwinkle Shell Ash as Filtration Loss Control Agent in Water- Based Drilling Mud
International Journal of Engineering Research and General Science, 2015
Experimental assessment of the suitability of Periwinkle Shell Ash (PSA) for use as filtration loss control additive in water-based drilling mud has been presented. Locally sourced periwinkle shells were soaked overnight in warm water treated with Sodium Chloride (NaCl) to remove dirt and any contaminant. Thereafter, the periwinkle shells were washed and air dried, and then heated in an electric muffle furnace at 995 o C. The calcined shells were then crushed with the aid of a jaw crusher and grinded to fine particles. The ensuing ash was then sieved through BS sieve (75microns) to obtain a fine ash (nanoparticles). This fine ash particles is the PSA used for the formulation of the mud sample of interest. The filtration characteristics of the formulated mud samples were tested using American Petroleum Institute (API) filter press and in accordance to API recommended practice for field testing water based drilling fluids (API RP 13B-1). Filtration control characteristics of the mud samples were demonstrated by the filtrate volume and the thickness and consistency of the mud filter cake deposited on the filter paper after 30 minutes of filtration. Physical examination of the filter cakes indicates that filter cake formed by sample C, prepare with 2.0 g of PSA, was thinner (0.75 mm thick) and more consistent than the rest. After 30 minutes of filtration, mud samples A, B, C, and D produced 7.7 ml, 7.2 ml, 6.7 ml, and 7.0 ml filtrate volumes, respectively. This imply that sample C formulated with 2.0 g of PSA, which produced the least filtrate volume (6.7 ml) after 30 minutes of filtration, demonstrated better filtration control characteristics than samples A, B, and D. Addition of PSA to the various mud samples improved the filtration characteristics of the formulated water-based drilling mud with respect to reduced filtrate volume and thinner and consistent mud filter cakes. PSA has proved to possess good filtration (fluid loss) control properties.
The design of drilling fluids is very important for the drilling operation success. The rheological properties play a key role in the performance of the drilling fluid. Therefore, studying the mud rheological properties of the water-based drilling fluid based on bentonite is essential. The main objectives of this study are to address the effect of pH changes on the rheological and filtration properties of the water-based drilling fluid based on bentonite and to provide a recommended pH range for this drilling fluid for a safe and high-performance drilling operation. Different samples of the water-based drilling fluid based on bentonite with different pH values were prepared, and the rheological properties such as plastic viscosity, yield point, and gel strength were measured. After that, the filtration test was performed under 300 psi differential pressure and 200 • F. The pH for the water-based drilling fluid based on bentonite significantly affects the mud rheology. The shear stress and shear rate relation were varying with the change in the pH. Increasing the pH from 8 to 12 resulted in decreasing the plastic viscosity by 53% and the yield point by 82%, respectively. The ratio of yield point / plastic viscosity was 1.4 for pH of 8 while it decreased to 0.5 for a pH of 11 and 12. There was a significant decrease in the gel strength readings by increasing the pH. The filtrate volume and filter cake thickness increased by increasing pH. The filtration volume increased from 9.5 cm 3 to 12.6 cm 3 by increasing the pH from 9 to 12. The filter cake thickness was 2 mm at 9 pH, while it was increased to 3.6 mm for 12 pH. It is recommended from the results to keep the pH of water-based drilling fluid based on bentonite in the range of 9 to 10 as it provides the optimum mud rheological and filtration properties. The findings of this study illustrated that keeping the pH in the range of 9 to 10 will reduce the plastic viscosity that will help in increasing the rate of penetration and reducing the required pump pressure to circulate the mud to the surface which will help to sustain the drilling operation. In addition, reducing the filtrate volume will produce a thin filter cake which will help in avoiding the pipe sticking and protect the environment. In general, optimizing the pH of the water-based drilling fluid based on bentonite in the range of 9 to 10 will improve the drilling operation and minimize the total cost.