A novel alkali-surfactant for optimization of filtercake removal in oil–gas well

AbstractThe main objective of this study is to improve the oil-based filtercake removal at the wellbore second interface through chemical method. The reductions in near-well permeability, bonding strength at wellbore second interface and acidizing treatment are the critical problems in oilfield upstream operations. One of the major causes has been identified as drilling fluid filtrate invasion during the drilling operations. This as result leads to near-well reduction in-flow capacity due to high drawdown pressure and wellbore instability. A number of chemical methods such as enzymes, acids, oxidizers, or their hybrids, have been used, however, due to the presence of a number of factors prior to its removal, there are still many challenges in cleaning oil-based filtercake from the wellbore surface. There is a need for development an effective method for improving oil-based filtercake removal. This study presents a novel Alkali-Surfactant (KV-MA) solution developed in the laboratory to optimize the filtercake removal of oil–gas wellbore. The Reynold number for KV-MA solution was found to be 9,068 indicating that turbulent flow regime will dominate in the annulus which enhances the cleaning efficiency. The wettability test established that, contact angle of 14° was a proper wetting agent. The calculated cleaning efficiency was 86.9%, indicating that it can effectively remove the oil-based filtercake. NaOH reacts with the polar components in the oil phase of the oil-based filtercake to produce ionized surface-active species; hence reducing the Interfacial Tension. Surfactant quickens the diffusion of ionized species from the interface to the bulk phase.

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Hole-Cleaning Fibers Improve Cuttings-Carrying Capacity

Journal of Petroleum Technology ◽

10.2118/0521-0063-jpt ◽

2021 ◽

Vol 73 (05) ◽

pp. 63-64

Author(s):

Chris Carpenter

Keyword(s):

Flow Regime ◽

Carrying Capacity ◽

Rheological Model ◽

Drilling Fluid ◽

Test Method ◽

Abu Dhabi ◽

Rheological Parameters ◽

Cleaning Efficiency ◽

Hole Cleaning ◽

Drilling Operations

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203147, “Investigating Hole-Cleaning Fibers’ Mechanism To Improve Cutting Carrying Capacity and Comparing Their Effectiveness With Common Polymeric Pills,” by Mohammad Saeed Karimi Rad, Mojtaba Kalhor Mohammadi, SPE, and Kourosh Tahmasbi Nowtarki, International Drilling Fluids, prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Hole cleaning in deviated wells is more challenging than in vertical wells because of the boycott effect or the eccentricity of the drillpipe. Poor hole cleaning can result in problems such as borehole packoff or excessive equivalent circulating density. The complete paper investigates a specialized fibrous material (Fiber 1) for hole-cleaning characteristics. The primary goal is to identify significant mechanisms of hole-cleaning fibers and their merits compared with polymeric high-viscosity pills. Hole-Cleaning Indices Based on a review of the literature, most effective parameters regarding hole cleaning in different well types were investigated. These parameters can be classified into the following five categories: - Well design (e.g., hole angle, drillpipe eccentricity, well trajectory) - Drilling-fluid properties (e.g., gel strength, mud weight) - Formation properties (e.g., lithology, cutting specific gravity, cuttings size and shape) - Hydraulic optimizations (e.g., flow regime, nozzle size, number of nozzles) - Drilling practices (e.g., drillpipe rotation speed, wellbore tortuosity, bit type, rate of penetration, pump rate) In this research, rheological parameters and parameters of the Herschel-Bulkley rheological model are considered to be optimization inputs to increase hole-cleaning efficiency of commonly used pills in drilling operations. The complete paper offers a detailed discussion of both the importance of flow regime and the role of the Herschel-Bulkley rheological model in reaching a better prognosis of drilling-fluid behavior at low shear rates. The properties of the fibrous hole-cleaning agent used in the complete paper are provided in Table 1. Test Method Two series of tests were performed. The medium of the first series is drilling water, with the goal of evaluating the efficiency of Fiber 1 in fresh pills. The second series of tests was per-formed with a simple polymeric mud as a medium common in drilling operations. Formulations and rheological properties of both test series are provided in Tables 4 and 5 of the complete paper, respectively.

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Wellbore Shielding Technique Increases Operative Window, Avoiding Formation Instability and Losses, Minimizing NPT, and Optimizing Drilling Operations in the Unconventional Plays

10.2523/iptc-21261-ms ◽

2021 ◽

Author(s):

Gaston Lopez ◽

Gonzalo Vidal ◽

Claus Hedegaard ◽

Reinaldo Maldonado

Keyword(s):

Drilling Fluid ◽

Drilling Fluids ◽

Wellbore Instability ◽

Lost Circulation ◽

Drilling Performance ◽

Drilling Parameters ◽

Vaca Muerta ◽

Drilling Operations ◽

Fracture Gradient ◽

Vaca Muerta Formation

Abstract Losses, wellbore instability, and influxes during drillings operations in unconventional fields result from continuous reactivity to the drilling fluid causing instability in the microfractured limestone of the Quintuco Formation in Argentina. This volatile situation becomes more critical when drilling operations are navigating horizontally through the Vaca Muerta Formation, a bituminous marlstone with a higher density than the Quintuco Formation. Controlling drilling fluids invasion between the communicating microfractures and connecting pores helps to minimize seepage losses, total losses, wellbore fluid influxes, and instabilities, reducing the non-productive time (NPT) caused by these problems during drilling operations. The use of conventional sealants – like calcium carbonate, graphite, asphalt, and other bridging materials – does not guarantee problem-free drilling operations. Also, lost circulation material (LCM) is restricted because the MWD-LWD tools clearances are very narrow in these slim holes. The challenge is to generate a strong and resistant seal separating the drilling fluid and the formation. Using an ultra-low-invasion technology will increase the operative fracture gradient window, avoid fluid invasion to the formation, minimize losses, and stop the cycle of fluid invasion and instability, allowing operations to maintain the designed drilling parameters and objectives safely. The ultra-low-invasion wellbore shielding technology has been applied in various fields, resulting in significantly improved drilling efficiencies compared to offset wells. The operator has benefited from the minimization of drilling fluids costs and optimization in drilling operations, including reducing the volume of oil-based drilling fluids used per well, fewer casing sections, and fewer requirements for cementing intervals to solve lost circulation problems. This paper will discuss the design of the ultra-low-invasion technology in an oil-based drilling fluid, the strategy for determining the technical limits for application, the evaluation of the operative window with an increase in the fracture gradient, the optimized drilling performance, and reduction in costs, including the elimination of NPT caused by wellbore instability.

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An Assessment of the Causes of Wellbore Instability and Stuck Pipe Occurrences in an Offshore Field, Niger Delta, Nigeria

African Journal of Engineering and Environment Research ◽

10.37703/ajoeer.org.ng/q12020/02 ◽

2020 ◽

Vol 1 (1) ◽

Keyword(s):

Cation Exchange ◽

Niger Delta ◽

Drilling Fluid ◽

Wellbore Stability ◽

Swelling Potential ◽

Offshore Drilling ◽

Wellbore Instability ◽

Clay Swelling ◽

Drilling Operations ◽

Cationic Exchange

Wellbore instability and consequential stuck pipe issues are a common challenge associated with offshore drilling. Usually, the effect of wellbore instability is an increase in nonproductive time, possible loss of tools and costly drilling operations. Hence, there is a need for wellbore stability analyses before and during drilling operations. In “Agaza Field”, offshore Niger Delta, wellbore instability problems were encountered at various depths between 3,696-4,270 ft.; 5,000-5,425 ft. and 7,600-8000 ft. intervals. Sixty-five ditch-cutting samples and composite log plots obtained from both wells were and analyzed to determine the clay swelling potential and the cationic exchange between the formation and the drilling fluid as well as causes of formation instability. Agaza-1 well showed evidence of tight hole at intervals between 4,200 and 7,600 ft. In Agaza-2, there were indications of wellbore stresses from 1,908 ft. to 2,030 ft. However, deeper than 4,225ft depth, high fluctuation of pore pressure coincided with wellbore instability between 4,810 ft. and 5,200 ft. The principal clay minerals present within the formations are Illite, Smectite and Smectite/Illite interlayered types. Result of the cation exchange analysis showed that high concentration of calcium and sodium in the shale is responsible for high dissociation of the constituent minerals hence making the shales unstable. Analysis has shown that samples at some intervals from both wells are associated with high swelling potential while average cation exchange value is 40 meq/100g. Therefore, the primary cause of wellbore instability and stuck pipe within the studied intervals are attributed to high swelling and reactivity over time due to fluidformation interaction. Keywords: Clay cationic exchange, Clay swelling potential, Offshore drilling challenges, Reactive shales. African

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Real Time Automation of Cutting Carrying Capacity Index to Predict Hole Cleaning Efficiency and Thereby Improve Well Drilling Performance

10.2118/206235-ms ◽

2021 ◽

Author(s):

Mohammed M Al-Rubaii ◽

Dhafer Al-Shehri ◽

Mohamed N Mahmoud ◽

Saleh M Al-Harbi ◽

Khaled A Al-Qahtani

Keyword(s):

Real Time ◽

Carrying Capacity ◽

Drilling Fluid ◽

Model Development ◽

Cleaning Efficiency ◽

Time Model ◽

Well Drilling ◽

Hole Cleaning ◽

Drilling Performance ◽

Drilling Operations

Abstract Hole cleaning efficiency is one of the major factors that affects well drilling performance. Rate of penetration (ROP) is highly dependent on hole cleaning efficiency. Hole cleaning performance can be monitored in real-time in order to make sure drilled cuttings generated are efficiently transported to surface. The objective of this paper to present a real time automated model to obtain hole cleaning efficiency and thus effectively adjust parameters as required to improve drilling performance. The process adopts a modified real time carrying capacity indicator. There are many hole cleaning models, methodologies, chemicals and correlations, but majority of these models do not simulate drilling operations sequences and are not dependent on practicality of drilling operations. The developed real time hole cleaning indicator can ensure continuous monitoring and evaluation of hole cleaning performance during drilling operations. The methodology of real time model development is by selecting offset mechanical drilling parameters and drilling fluid parameters where collected, analyzed, tested and validated to model strong hole cleaning efficiency indicator that can extremely participate and facilitate a position in drilling automations and fourth industry revolution. The automated hole cleaning model is utilizing real time sensors of drilling and validate the strongest relationships among the variables. The study, analysis, test and validation of the relationships will reveal the significant parameters that will contribute massively for model development procedures. The model can be run as well by using the real time sensors readings and their inputs to be fed into the developed automated model. The developed model of real time carrying capacity indicator profile will be shown as function of depth, drilling fluid density, flow rate of mud pump or mud pump output, and other important factors will be illustrated by details. The model has been developed and validated in the field of drilling operations to empower the drilling teams for better and understandable monitoring and evaluation of hole cleaning efficiency while performing drilling operations. The real time model can provide a vision for better control of mud additives and that will contribute to mud cost effectiveness. The automated model of hole cleaning efficiency optimized the rate of penetration (ROP) by 50% in well drilling performance as a noticeable and valuable improvement. This optimum improvement saved cost and time of rig and drilling of wells and contributed to accelerate wells’ delivery. The innovative real time model was developed to optimize drilling and operations efficiency by using the surface rig sensors and interpret the downhole measurements and that can lead innovatively to other important hole cleaning indicators and other tactics for better development of downhole measurements models that can participate for optimized drilling efficiency.

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Assessing the Relation between Mud Components and Rheology for Loss Circulation Prevention Using Polymeric Gels: A Machine Learning Approach

Energies ◽

10.3390/en14051377 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1377

Author(s):

Musaab I. Magzoub ◽

Raj Kiran ◽

Saeed Salehi ◽

Ibnelwaleed A. Hussein ◽

Mustafa S. Nasser

Keyword(s):

Machine Learning ◽

Rheological Properties ◽

Nearest Neighbor ◽

Drilling Fluid ◽

Gradient Boosting ◽

K Nearest Neighbor ◽

Wide Range ◽

Machine Learning Approach ◽

Drilling Operations

The traditional way to mitigate loss circulation in drilling operations is to use preventative and curative materials. However, it is difficult to quantify the amount of materials from every possible combination to produce customized rheological properties. In this study, machine learning (ML) is used to develop a framework to identify material composition for loss circulation applications based on the desired rheological characteristics. The relation between the rheological properties and the mud components for polyacrylamide/polyethyleneimine (PAM/PEI)-based mud is assessed experimentally. Four different ML algorithms were implemented to model the rheological data for various mud components at different concentrations and testing conditions. These four algorithms include (a) k-Nearest Neighbor, (b) Random Forest, (c) Gradient Boosting, and (d) AdaBoosting. The Gradient Boosting model showed the highest accuracy (91 and 74% for plastic and apparent viscosity, respectively), which can be further used for hydraulic calculations. Overall, the experimental study presented in this paper, together with the proposed ML-based framework, adds valuable information to the design of PAM/PEI-based mud. The ML models allowed a wide range of rheology assessments for various drilling fluid formulations with a mean accuracy of up to 91%. The case study has shown that with the appropriate combination of materials, reasonable rheological properties could be achieved to prevent loss circulation by managing the equivalent circulating density (ECD).

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A Generalized Model for the Field Assessment of Drilling Fluid Viscoelasticity

10.2118/205953-ms ◽

2021 ◽

Author(s):

Chen Hongbo ◽

Okesanya Temi ◽

Kuru Ergun ◽

Heath Garett ◽

Hadley Dylan

Keyword(s):

Drilling Fluid ◽

Field Testing ◽

Field Application ◽

Testing Equipment ◽

Drilling Fluids ◽

Rotational Viscometer ◽

Generalized Model ◽

Fluid Elasticity ◽

Field Samples ◽

Drilling Operations

Abstract Recent studies highlight the significant role of drilling fluid elasticity in particle suspension and hole cleaning during drilling operations. Traditional methods to quantify fluid elasticity require the use of advanced rheometers not suitable for field application. The main objectives of the study were to develop a generalized model for determining viscoelasticity of a drilling fluid using standard field-testing equipment, investigate the factors influencing drilling fluid viscoelasticity in the field, and provide an understanding of the viscoelasticity concept. Over 80 fluid formulations used in this study included field samples of oil-based drilling fluids as well as laboratory samples formulated with bentonite and other polymers such as partially-hydrolyzed polyacrylamide, synthesized xanthan gum, and polyacrylic acid. Detailed rheological characterizations of these fluids used a funnel viscometer and a rotational viscometer. Elastic properties of the drilling fluids (quantified in terms of the energy required to cause an irreversible deformation in the fluid's structure) were obtained from oscillatory tests conducted using a cone-and-plate type rheometer. Using an empirical approach, a non-iterative model for quantifying elasticity correlated test results from a funnel viscometer and a rotational viscometer. The generalized model was able to predict the elasticity of drilling fluids with a mean absolute error of 5.75%. In addition, the model offers practical versatility by requiring only standard drilling fluid testing equipment to predict viscoelasticity. Experimental results showed that non-aqueous fluid (NAF) viscoelasticity is inversely proportional to the oil-water ratio and the presence of clay greatly debilitates the elasticity of the samples while enhancing their viscosity. The work efforts present a model for estimating drilling fluid elasticity using standard drilling fluid field-testing equipment. Furthermore, a revised approach helps to describe the viscoelastic property of a fluid that involves quantifying the amount of energy required to irreversibly deform a unit volume of viscoelastic fluid. The methodology, combined with the explanation of the viscoelasticity concept, provides a practical tool for optimizing drilling operations based on the viscoelasticity of drilling fluids.

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Interdisciplinary Approach for Wellbore Stability During Slimhole Drilling at Volga-Urals Basin Oilfield

10.2118/206562-ms ◽

2021 ◽

Author(s):

Anna Vladimirovna Norkina ◽

Sergey Mihailovich Karpukhin ◽

Konstantin Urjevich Ruban ◽

Yuriy Anatoljevich Petrakov ◽

Alexey Evgenjevich Sobolev

Keyword(s):

Drilling Fluid ◽

Interdisciplinary Approach ◽

Wellbore Stability ◽

Vertical Wells ◽

Wellbore Instability ◽

Water Based ◽

Chemical Studies ◽

Fluid Rheology ◽

Selection Of

Abstract The design features and the need to use a water-based solution make the task of ensuring trouble-free drilling of vertical wells non-trivial. This work is an example of an interdisciplinary approach to the analysis of the mechanisms of instability of the wellbore. Instability can be caused by a complex of reasons, in this case, standard geomechanical calculations are not enough to solve the problem. Engineering calculations and laboratory chemical studies are integrated into the process of geomechanical modeling. The recommendations developed in all three areas are interdependent and inseparable from each other. To achieve good results, it is necessary to comply with a set of measures at the same time. The key tasks of the project were: determination of drilling density, tripping the pipe conditions, parameters of the drilling fluid rheology, selection of a system for the best inhibition of clay swelling.

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Development of Digital Twins for Drilling Fluids: Local Velocities for Hole Cleaning and Rheology Monitoring

10.1115/omae2021-62987 ◽

2021 ◽

Author(s):

Mehrdad Gharib Shirangi ◽

Roger Aragall ◽

Reza Ettehadi ◽

Roland May ◽

Edward Furlong ◽

...

Keyword(s):

Machine Learning ◽

Rheological Properties ◽

Drilling Fluid ◽

Training Data ◽

Drilling Fluids ◽

Hole Cleaning ◽

Digital Twins ◽

Wide Range ◽

Drilling Operations ◽

Cuttings Bed

Abstract In this work, we present our advances to develop and apply digital twins for drilling fluids and associated wellbore phenomena during drilling operations. A drilling fluid digital twin is a series of interconnected models that incorporate the learning from the past historical data in a wide range of operational settings to determine the fluids properties in realtime operations. From several drilling fluid functionalities and operational parameters, we describe advancements to improve hole cleaning predictions and high-pressure high-temperature (HPHT) rheological properties monitoring. In the hole cleaning application, we consider the Clark and Bickham (1994) approach which requires the prediction of the local fluid velocity above the cuttings bed as a function of operating conditions. We develop accurate computational fluid dynamics (CFD) models to capture the effects of rotation, eccentricity and bed height on local fluid velocities above cuttings bed. We then run 55,000 CFD simulations for a wide range of operational settings to generate training data for machine learning. For rheology monitoring, thousands of lab experiment records are collected as training data for machine learning. In this case, the HPHT rheological properties are determined based on rheological measurement in the American Petroleum Institute (API) condition together with the fluid type and composition data. We compare the results of application of several machine learning algorithms to represent CFD simulations (for hole cleaning application) and lab experiments (for monitoring HPHT rheological properties). Rotating cross-validation method is applied to ensure accurate and robust results. In both cases, models from the Gradient Boosting and the Artificial Neural Network algorithms provided the highest accuracy (about 0.95 in terms of R-squared) for test datasets. With developments presented in this paper, the hole cleaning calculations can be performed more accurately in real-time, and the HPHT rheological properties of drilling fluids can be estimated at the rigsite before performing the lab experiments. These contributions advance digital transformation of drilling operations.

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Synthesis and development of smart drilling fluids using nanoparticles to tailor their transport properties for enhanced drilling operations

10.12681/eadd/43961 ◽

2018 ◽

Author(s):

Ζήσης Βρύζας

Keyword(s):

Transport Properties ◽

Yield Stress ◽

Drilling Fluid ◽

Fluid Loss ◽

Drilling Fluids ◽

Natural Fractures ◽

Custom Made ◽

Drilling Operations ◽

Induced Fractures

Η γεώτρηση αποτελεί την πλέον δαπανηρή εργασία σε μια καμπάνια εξεύρεσης και παραγωγής υδρογονανθράκων. Πέραν αυτού συνιστά και την μοναδική διεργασία που δίνει τη δυνατότητα ακριβούς προσδιορισμού των αποθεμάτων στο υπέδαφος. Ο πολφός (γεωτρητικά ρευστά) είναι το ‘αίμα’ της γεώτρησης: παρέχει πίεση, μεταφορά τριμμάτων/θραυσμάτων από τον πυθμένα του φρέατος, ψύξη και λίπανση κοπτικού και στήλης, καθώς επίσης διατηρεί τα θραύσματα εν αιωρήσει όταν υπάρχει διακοπή της κυκλοφορίας. Ως ρευστό γεώτρησης (drilling fluid) χρησιμοποιείται συνήθως ένα αιώρημα πηλού και άλλων υλικών σε νερό. Τα ρευστά διάτρησης με βάση το νερό αποτελούνται από α) νερό, το οποίο αποτελεί την συνεχή φάση και παρέχει το αρχικό ιξώδες (φρέσκο ή θαλασσινό), β) ενεργά στερεά για την ενίσχυση του ιξώδους και του σημείου διαρροής (μπεντονίτης, που συνιστάται στην περίπτωση του φρέσκου νερού και ατταπουλγίτης, αμίαντος ή σιπιόλιθος, που συνιστώνται στην περίπτωση του θαλασσινού νερού), και γ) αδρανή στερεά για την επίτευξη της απαιτούμενης πυκνότητας (βαρύτης, θειούχος μόλυβδος, σιδηρομεταλλεύματα ή χαλαζιακά υλικά).Τα γεωτρητικά ρευστά αποτελούν το 10-20% του συνολικού κόστους κατά την διάρκεια μιας γεώτρησης. Ποσοστό πολύ υψηλό όταν μιλάμε για επενδύσεις εκκατομυρίων δολλαρίων. Λόγω των ολοένα πιο βαθιών αλλά και περίπλοκων γεωλογικών σχηματισμών υπάρχει τεράστια ανάγκη από την πετρελαική βιομηχανία για καινούργια και περισσότερο αποδοτικά γεωτρητικά ρευστά τα οποία θα μπορούν να ανταπεξέλθουν στα ολοένα και πιο απαιτητικά περβάλλοντα θερμοκρασίας και πίεσης. Τα σημαντικότερα ζητήματα τα οποία καλούνται να ανταποκριθούν τα ρευστά είναι οι ολοένα αυξανόμενες συνθήκες πίεσης και θερμοκρασίας στο υπέδαφος που είναι απόροια της αναζήτησης υδρογονανθράκων σε πλέον δύσβατες περιοχές με μεγαλύτερα βάθη που αυξάνουν τους κινδύνους και το κόστος για μια γεώτρηση. Η απώλεια ρευστού κυκλοφορίας (fluid loss) είναι ένα από τα σημαντικότερα και πλέον δαπανηρά προβλήματα κατά την διαδικασία μιας γεώτρησης. Ως απώλεια ρευστού κυκλοφορίας ορίζεται η συνολική ή μερική απώλεια των ρευστών της γεώτρησης σε εξαιρετικά διαπερατές ζώνες (porous sands), σε σπηλαιώδεις σχηματισμούς (cavernous zones), σε φυσικές ρηγματώσεις (natural fractures) και σε ρηγματώσεις προκαλούμενες κατά τη διάτρηση (induced fractures). Τα τελευταία χρόνια έχουν γίνει αρκετές προσπάθειες για την βελτίωση των γεωτρητικών ρευστών με την χρήση νανοσωματιδίων, τα οποία έχουν τη δυνατότητα να βελτιώσουν τις ιδιότητες των γεωτρητικών ρευστών όταν προστίθενται ακόμα και σε χαμηλές συγκεντρώσεις (<1 wt%). Οι μοναδικές τους ιδιότητες σχετίζονται με το μικρό τους μέγεθος και επομένως τον εξαιρετικά μεγάλο λόγο επιφάνειας προς όγκο.Σε αυτή την εργασία, εξετάστηκαν διάφορα εμπορικά νανοσωματίδια (Fe2O3, Fe3O4, SiO2) καθώς επίσης συντέθηκαν, με την μέθοδο της συγκαταβύθισης, νανοσωματιδία μαγνητίτη (custom-made Fe3O4), με και χωρίς επικάλυψη κιτρικού οξέος, τα οποία ερευνήθηκαν ως προς την ικανότητα τους να βελτιώσουν τις ρεολογικές ιδιότητες και την απώλεια ρευστών σε αιωρήματα μπετονίτη. Προκειμένου να χαρακτηρισθούν φυσικοχημικά τα αιωρήματα υπέστησαν ξήρανση με κοκκοποίηση σε θερμοκρασία υγρού Ν2 και κρυοξήρανση. Η μορφολογία, η κρυσταλλική δομή και οι επιφανειακές ομάδες των ξηρών κόνεων εξετάσθηκαν με ηλεκτρονική μικροσκοπία HR-TΕM, περίθλαση ακτίνων Χ (XRD), φυσική ρόφηση Ν2 και φασματοσκοπία FTIR. Οι αλληλεπιδράσεις των σωματιδίων μπετονίτη με τα νανοσωματίδια και οι διάφορες δομές που δημιουργούνται και πως τελικά αυτές επηρεάζουν τις ρεολογικές ιδιότητες των αιωρημάτων εξετάστηκαν με το HR-TEM στους 25°C και 60°C. Με βάση τις εικόνες από το HR-TEM, ένα μοντέλο αλληλεπιδράσεων μεταξύ των διαφορετικών τύπων νανοσωματιδίων και σωματιδίων μπετονίτη δημιουργήθηκε για πρώτη φορά για τέτοια αιωρήματα. Οι ρεολογικές ιδιότητες των παραγόμενων δειγμάτων εξετάστηκαν και σε συνθήκες ατμοσφαιρικής πίεσης (μέχρι 70°C) με την χρήση περιστροφικού ιξωδόμετρου (Grace M3600-Couette type geometry) αλλά και σε συνθήκες υψηλής πίεσης και θερμοκρασίας (69 bar-121°C) (Chandler 7600 HPHT viscometer). Το μοντέλο Herschel-Bulkley χρησιμοποιήθηκε για να περιγράψει τη μεταβολή του ιξώδους με τη μεταβολή των ρεολογικών παραμέτρων δείχνοντας εξαιρετική εφαρμογή για τις διαφορετικές πειραματικές μετρήσεις με συντελεστές συσχέτισης (R2) >0.99 σε όλες τις περιπτώσεις. Οι ρεολογικές μετρήσεις έδειξαν ότι η προσθήκη των νανοσωματιδίων βελτιώνει σημαντικά τις ρεολογικές ιδιότητες των αιωρημάτων μπετονίτη στις διάφορες συνθήκες πίεσης και θερμοκρασίας. Οι απώλειες ρευστών (fluid loss) εξετάστηκαν με φιλτροπρέσες υψηλής πίεσης και θερμοκρασίας (20.7 bar και 121°C) οι οποίες υπολογίζουν τον ρυθμό διήθησης του πολφού μέσω του χρησιμοποιούμενου φίλτρου (κεραμικός δίσκος). Η μεγαλύτερη μείωση στην απώλεια ρευστών επιτεύχθηκε για το δείγμα που περιείχε 0.5 wt% custom-made Fe3O4 με μείωση -40% σε σχέση με το αρχικό δείγμα μπετονίτη που δείχνει την τεράστια ικανότητα των νανοσωματιδίων να βελτιώσουν σημαντικά τις απώλειες ρευστών ακόμα και σε τόσο μικρές συγκεντρώσεις. Τέλος, εξετάστηκε η ικανότητα των παραγόμενων ρευστών να αλλάζουν τις ρεολογικές τους ιδιότητες υπό την επίδραση διάφορων μαγνητικών πεδίων (μέχρι 0.7 Tesla). Τα αποτελέσματα έδειξαν ότι τα καινούργια γεωτρητικά ρευστά έχουν την ικανότητα να αυξάνουν την τάση διολίσθησης (yield stress) έως και 300% σε σχέση με αυτή που μετρήθηκε χωρίς την εφαρμογή μαγνητικού πεδίου. Αυτό είναι κάτι πολύ σημαντικό που επιτρέπει την χρήση έξυπνων ρευστών (smart drilling fluids) τα οποία μπορούν να εξοικονομήσουν και χρόνο αλλά και κόστη κατά την διάρκεια μιας γεώτρησης.Τα νανοσωματίδια δείχνουν πολλές ελπιδοφόρες δυνατότητες σε εφαρμογές γεωτρήσεων αφού έχουν τη δυνατότητα να βελτιώσουν ή και να λύσουν το πρόβλημα της απώλειας ρευστών, όταν προστίθενται ακόμα και σε χαμηλές συγκεντρώσεις (>0.5 wt%), ενώ ταυτόχρονα βελτιστοποιούν τις ρεολογικές ιδιότητες των γεωτρητικών ρευστών. Η χρήση τους για την ανάπτυξη βελτιωμένων γεωτρητικών ρευστών υπόσχεται να αλλάξει την βιομηχανία των γεωτρήσεων και να την βοηθήσει να εξορυχθούν πολύπλοκοι γεωλογικοί σχηματισμοί πιο αποδοτικά αλλά και οικονομικά.

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Comparative Analysis of the Effect of Barite and Hematite on the Rheology of Water-Based Drilling Mud

10.53902/tpe.2021.01.000508 ◽

2021 ◽

Vol 1 (2) ◽

Author(s):

Osei H

Keyword(s):

Rheological Properties ◽

Drilling Fluid ◽

Attrition Rate ◽

Drilling Mud ◽

Cleaning Efficiency ◽

Drilling Operation ◽

Water Based ◽

Petroleum Resources ◽

Drilling Muds ◽

The Impact

High demand for oil and gas has led to exploration of more petroleum resources even at remote areas. The petroleum resources are found in deeper subsurface formations and drilling into such formations requires a well-designed drilling mud with suitable rheological properties in order to avoid or reduce associated drilling problems. This is because rheological properties of drilling muds have considerable effect on the drilling operation and cleaning of the wellbore. Mud engineers therefore use mud additives to influence the properties and functions of the drilling fluid to obtain the desired drilling mud properties especially rheological properties. This study investigated and compared the impact of barite and hematite as weighting agents for water-based drilling muds and their influence on the rheology. Water-based muds of different concentrations of weighting agents (5%, 10%, 15% and 20% of the total weight of the drilling mud) were prepared and their rheological properties determined at an ambient temperature of 24ᵒC to check their impact on drilling operation. The results found hematite to produce higher mud density, plastic viscosity, gel strength and yield point when compared to barite at the same weighting concentrations. The higher performance of the hematite-based muds might be attributed to it having higher specific gravity, better particle distribution and lower particle attrition rate and more importantly being free from contaminants. The water-based muds with hematite will therefore be more promising drilling muds with higher drilling and hole cleaning efficiency than those having barite.

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