Prevention of Barite Sag in Oil-Based Drilling Fluids Using a Mixture of Barite and Ilmenite as Weighting Material

Drilling high-pressure high-temperature (HPHT) wells requires a special fluid formulation that is capable of controlling the high pressure and is stable under the high downhole temperature. Barite-weighted fluids are common for such purpose because of the good properties of barite, its low cost, and its availability. However, solids settlement is a major problem encountered with this type of fluids, especially at elevated downhole temperatures. This phenomenon is known as barite sag, and it is encountered in vertical and directional wells under static or dynamic conditions leading to serious well control issues. This study aims to evaluate the use of barite-ilmenite mixture as a weighting agent to prevent solids sag in oil-based muds at elevated temperatures. Sag test was conducted under static conditions (vertical and inclined) at 350 °F and under dynamic conditions at 120 °F to determine the optimum ilmenite concentration. Afterward, a complete evaluation of the drilling fluid was performed by monitoring density, electrical stability, rheological and viscoelastic properties, and filtration performance to study the impact of adding ilmenite on drilling fluid performance. The results of this study showed that adding ilmenite reduces sag tendency, and only 40 wt.% ilmenite (from the total weighting material) was adequate to eliminate barite sag under both static and dynamic conditions with a sag factor of around 0.51. Adding ilmenite enhanced the rheological and viscoelastic properties and the suspension of solid particles in the drilling fluid, which confirmed sag test results. Adding ilmenite slightly increased the density of the drilling fluid, with a slight decrease in the electrical stability within the acceptable range of field applications. Moreover, a minor improvement in the filtration performance of the drilling fluid and filter cake sealing properties was observed with the combined weighting agent. The findings of this study provide a practical solution to the barite sag issue in oil-based fluids using a combination of barite and ilmenite powder as a weighting agent to drill HPHT oil and gas wells safely and efficiently with such type of fluids.

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A Combined Barite–Ilmenite Weighting Material to Prevent Barite Sag in Water-Based Drilling Fluid

Materials ◽

10.3390/ma12121945 ◽

2019 ◽

Vol 12 (12) ◽

pp. 1945 ◽

Cited By ~ 15

Author(s):

Salem Basfar ◽

Abdelmjeed Mohamed ◽

Salaheldin Elkatatny ◽

Abdulaziz Al-Majed

Keyword(s):

Rheological Properties ◽

Base Fluid ◽

Drilling Fluid ◽

Fluid Density ◽

Fluid Filtration ◽

Dynamic Conditions ◽

Filtration Performance ◽

Water Based ◽

Static Conditions ◽

The Impact

Barite sag is a serious problem encountered while drilling high-pressure/high-temperature (HPHT) wells. It occurs when barite particles separate from the base fluid leading to variations in drilling fluid density that may cause a serious well control issue. However, it occurs in vertical and inclined wells under both static and dynamic conditions. This study introduces a combined barite–ilmenite weighting material to prevent the barite sag problem in water-based drilling fluid. Different drilling fluid samples were prepared by adding different percentages of ilmenite (25, 50, and 75 wt.% from the total weight of the weighting agent) to the base drilling fluid (barite-weighted). Sag tendency of the drilling fluid samples was evaluated under static and dynamic conditions to determine the optimum concentration of ilmenite which was required to prevent the sag issue. A static sag test was conducted under both vertical and inclined conditions. The effect of adding ilmenite to the drilling fluid was evaluated by measuring fluid density and pH at room temperature, and rheological properties at 120 °F and 250 °F. Moreover, a filtration test was performed at 250 °F to study the impact of adding ilmenite on the drilling fluid filtration performance and sealing properties of the formed filter cake. The results of this study showed that adding ilmenite to barite-weighted drilling fluid increased fluid density and slightly reduced the pH within the acceptable pH range (9–11). Ilmenite maintained the rheology of the drilling fluid with a minimal drop in rheological properties due to the HPHT conditions, while a significant drop was observed for the base fluid (without ilmenite). Adding ilmenite to the base drilling fluid significantly reduced sag factor and 50 wt.% ilmenite was adequate to prevent solids sag in both dynamic and static conditions with sag factors of 0.33 and 0.51, respectively. Moreover, HPHT filtration results showed that adding ilmenite had no impact on filtration performance of the drilling fluid. The findings of this study show that the combined barite–ilmenite weighting material can be a good solution to prevent solids sag issues in water-based fluids; thus, drilling HPHT wells with such fluids would be safe and effective.

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Enhancing the Stability of Invert Emulsion Drilling Fluid for Drilling in High-Pressure High-Temperature Conditions

Energies ◽

10.3390/en11092393 ◽

2018 ◽

Vol 11 (9) ◽

pp. 2393 ◽

Cited By ~ 11

Author(s):

Salaheldin Elkatatny

Keyword(s):

High Pressure ◽

High Temperature ◽

Rheological Properties ◽

Drilling Fluid ◽

Electrical Stability ◽

Dynamic Conditions ◽

High Pressure High Temperature ◽

Invert Emulsion ◽

The Stability ◽

Filtration Properties

Drilling in high-pressure high-temperature (HPHT) conditions is a challenging task. The drilling fluid should be designed to provide high density and stable rheological properties. Barite is the most common weighting material used to adjust the required fluid density. Barite settling, or sag, is a common issue in drilling HPHT wells. Barite sagging may cause many problems such as density variations, well-control problems, stuck pipe, downhole drilling fluid losses, or induced wellbore instability. This study assesses the effect of using a new copolymer (based on styrene and acrylic monomers) on the rheological properties and the stability of an invert emulsion drilling fluid, which can be used to drill HPHT wells. The main goal is to prevent the barite sagging issue, which is common in drilling HPHT wells. A sag test was performed under static (vertical and 45° incline) and dynamic conditions in order to evaluate the copolymer’s ability to enhance the suspension properties of the drilling fluid. In addition, the effect of this copolymer on the filtration properties was performed. The obtained results showed that adding the new copolymer with 1 lb/bbl concentration has no effect on the density and electrical stability. The sag issue was eliminated by adding 1 lb/bbl of the copolymer to the invert emulsion drilling fluid at a temperature >300 °F under static and dynamic conditions. Adding the copolymer enhanced the storage modulus by 290% and the gel strength by 50%, which demonstrated the power of the new copolymer to prevent the settling of the barite particles at a higher temperature. The 1 lb/bbl copolymer’s concentration reduced the filter cake thickness by 40% at 400 °F, which indicates the prevention of barite settling at high temperature.

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Prevention of Barite Sag in Water-Based Drilling Fluids by A Urea-Based Additive for Drilling Deep Formations

Sustainability ◽

10.3390/su12072719 ◽

2020 ◽

Vol 12 (7) ◽

pp. 2719 ◽

Cited By ~ 2

Author(s):

Abdelmjeed Mohamed ◽

Saad Al-Afnan ◽

Salaheldin Elkatatny ◽

Ibnelwaleed Hussein

Keyword(s):

Base Fluid ◽

Drilling Fluid ◽

Gel Strength ◽

Optimum Concentration ◽

Drilling Fluids ◽

Filtration Performance ◽

Water Based ◽

The Stability ◽

Static Conditions ◽

The Impact

Barite sag is a challenging phenomenon encountered in deep drilling with barite-weighted fluids and associated with fluid stability. It can take place in vertical and directional wells, whether in dynamic or static conditions. In this study, an anti-sagging urea-based additive was evaluated to enhance fluid stability and prevent solids sag in water-based fluids to be used in drilling, completion, and workover operations. A barite-weighted drilling fluid, with a density of 15 ppg, was used with the main drilling fluid additives. The ratio of the urea-based additive was varied in the range 0.25–3.0 vol.% of the total base fluid. The impact of this anti-sagging agent on the sag tendency was evaluated at 250 °F using vertical and inclined sag tests. The optimum concentration of the anti-sagging agent was determined for both vertical and inclined wells. The effect of the urea-additive on the drilling fluid rheology was investigated at low and high temperatures (80 °F and 250 °F). Furthermore, the impact of the urea-additive on the filtration performance of the drilling fluid was studied at 250 °F. Adding the urea-additive to the drilling fluid improved the stability of the drilling fluid, as indicated by a reduction in the sag factor. The optimum concentration of this additive was found to be 0.5–1.0 vol.% of the base fluid. This concentration was enough to prevent barite sag in both vertical and inclined conditions at 250 °F, with a sag factor of around 0.5. For the optimum concentration, the yield point and gel strength (after 10 s) were improved by around 50% and 45%, respectively, while both the plastic viscosity and gel strength (after 10 min) were maintained at the desired levels. Moreover, the anti-sagging agent has no impact on drilling fluid density, pH, or filtration performance.

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Research on Numerical Simulation of Support Interference for Dynamic Derivatives at Hypersonic Flight Speeds

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1016.495 ◽

2014 ◽

Vol 1016 ◽

pp. 495-500

Author(s):

Xu Liu ◽

Wei Liu ◽

Yun Fei Zhao

Keyword(s):

Numerical Simulation ◽

Unsteady Flow ◽

Time Derivative ◽

Least Square ◽

Step Method ◽

Time Step ◽

Dynamic Conditions ◽

Static Conditions ◽

Support Interference ◽

The Impact

The research on dynamic derivative under the dynamic unsteady condition is one of the most difficult aspects of the aircraft development process. For the special experiment of dynamic derivatives, no numerical simulation of support interference has yet been systematically studied. The numerical simulation of support interference for identification of dynamic derivatives with 7o blunted cone under the hypersonic condition was done in this paper. The 2-order Roe scheme and the dual-time-step method based on LU-SGS were respectively applied to discrete of the spatial and time derivative of the unsteady flow. A least square method based on the Etkin unsteady aerodynamic model was used for identification of dynamic derivatives. Hypersonic missile module was adopted as a verification example, and the numerical calculation results are consistent with the experimental results. For two different sting support forms with 7o blunted cone, the impact of sting support interference on dynamic derivatives was studied. Results show the moment coefficients of two support forms under static conditions are essentially the same, while there is a big difference in the pitch damping derivatives under dynamic conditions. The support interference of nonlinear aerodynamic loads resulted from the shock wave induced separation and other unsteady flow structures under dynamic conditions is far more complicated than that under static conditions, and the correction law of support interference under static conditions cannot be applied directly to the unsteady dynamic situations.

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Filter Cake Properties of Water-Based Drilling Fluids Under Static and Dynamic Conditions Using Computed Tomography Scan

Journal of Energy Resources Technology ◽

10.1115/1.4023483 ◽

2013 ◽

Vol 135 (4) ◽

Cited By ~ 35

Author(s):

Salaheldin Elkatatny ◽

Mohamed Mahmoud ◽

Hisham A. Nasr-El-Din

Keyword(s):

Computed Tomography ◽

Filter Cake ◽

Drilling Fluid ◽

Filter Press ◽

Filter Medium ◽

Drilling Fluids ◽

Dynamic Conditions ◽

Water Based ◽

Porosity And Permeability ◽

Static Conditions

Previous studies considered the water-based drilling fluid filter cake as homogenous, containing one layer with an average porosity and permeability. The filter cake was recently proved to be heterogeneous, containing two layers with different properties (thickness, porosity and permeability). Heterogeneity of the filter cake plays a key role in the design of chemical treatments needed to remove the filter cake. The objectives of this study are to describe filter cake buildup under static and dynamic conditions, determine change in the filter medium properties, and obtain the local filtration properties for each layer in the filter cake. A high pressure high temperature (HPHT) filter press was used to perform the filtration process at 225 °F and 300 psi. A CT (computed tomography) scanner was used to measure the thickness and porosity of the filter cake. The results obtained from the CT scan showed that under static conditions, the formation of filter cake changed from compression to buildup; while under dynamic conditions, the filter cake was formed under continuous buildup. The CT results explained the changes in the thickness and porosity of each layer of the filter cake with time. The CT scans showed the change in the properties of the ceramic disk, such as porosity and permeability, which affect the calculation of the filter cake permeability. The change of the properties of the filter medium was ignored in previous studies.

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Integrated Experimental and Analytical Wellbore Strengthening Solutions by Mud Plastering Effects

Journal of Energy Resources Technology ◽

10.1115/1.4032236 ◽

2016 ◽

Vol 138 (3) ◽

Cited By ~ 25

Author(s):

Saeed Salehi ◽

Raj Kiran

Keyword(s):

High Pressure ◽

High Temperature ◽

Drilling Fluid ◽

Wellbore Stability ◽

Stress Profile ◽

Laboratory Studies ◽

Mud Cake ◽

Stress Changes ◽

Wellbore Strengthening ◽

The Impact

Wellbore stability has plagued oil industry for decades. Inclusion of the mud in drilling and the effect of mud cake build up incorporate very complex chemical, thermal, mechanical, and physical phenomena. It is very difficult to quantify all these phenomena in one model. The after effects of mud cake buildup, its permeability and variation in thickness with time alter the actual stress profile of the formation. To see the impact of the whole mechanism, a combination of laboratory studies and numerical modeling is needed. This paper includes the procedure and results on stress profiles in near wellbore region based on laboratory studies of mud cake buildup in high pressure and high temperature environment using permeability plug apparatus (PPA). The damaged formation zone is very susceptible to drilling fluid and results in alteration of existing pore pressure and fracture pressure. This paper presents integrated experimental and analytical solutions for wellbore strengthening due to mud cake plastering. Conducting experiments on rock core disks has provided more realistic results which can resemble to field conditions. The experimental work here provides an insight to effect of mud cake build up at high pressure and high temperature conditions using a heterogeneous filtration medium prepared from different sandstone cores. Results were used in the analytical model to see the effect of stresses in the formation. The primary objective is to investigate the wellbore hoop stress changes due to formation of filter cake by mud plastering using the analytical models built upon the laboratory results. The models developed in this work provide insights to quantify on wellbore plastering effects by mud cake build up.

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Enhanced Outside-In Signaling Through the Prothrombotic Pro33 Variant of Integrin αIIbβ3 in Adherent Platelets Under Static and Flow Dynamic Conditions

Blood ◽

10.1182/blood.v118.21.2199.2199 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2199-2199 ◽

Cited By ~ 1

Author(s):

Marianna Gyenes ◽

Markus Hasse ◽

Volker R. Stoldt ◽

Abdelouahid El-Khattouti ◽

Khon C. Huynh ◽

...

Keyword(s):

Myocardial Infarction ◽

Shear Stress ◽

Fold Increase ◽

Flow Conditions ◽

Flow Dynamic ◽

Integrin Αiibβ3 ◽

Dynamic Conditions ◽

Shear Rates ◽

Static Conditions ◽

The Impact

Abstract Abstract 2199 Objectives: Platelet integrin αIIbβ3 is polymorphic at residue 33 (Leu33/HPA-1a or Pro33/HPA-1b). In patients with coronary artery disease, the Pro33 isoform is associated with premature manifestation of myocardial infarction (Zotz et al., JTH 2005). Based on this finding, it has been postulated that the Pro33 variant of αIIbβ3 has a prothrombotic phenotype. Moreover, several studies have shown that elevated shear stress can activate platelets leading to shear-induced platelet aggregation contributing to acute myocardial infarction. Thus, it has been reported that pathological shear stress directly regulates αIIbβ3 (Feng et al., Am J Physiol Cell Physiol 2006). We have shown that adherent Pro33 platelets have a higher resistance than Leu33 platelets upon exposure to high shear rates (Loncar et al, Thromb J 2007). We now studied the impact of the Leu33/Pro33 polymorphism on αIIbβ3-mediated outside-in signaling under static and flow dynamic conditions in the presence or absence of Mn2+, analyzing the Src pY418 and FAK pY397 activities. Methods: Adhesion assays were performed with 10 or 100 μg/ml of immobilized fibrinogen for different incubation times with washed human platelets in the presence or absence of Mn2+ (0.5 mM). Mn2+ induces the active conformation of αIIbβ3. Src pY418 and FAK pY397 activities were determined by Western blotting and quantified densitometrically. Control experiments were performed with 1% BSA. Adhesion experiments under flow conditions were carried out with a cone-plate viscometer. Results: Under static conditions, Pro33 platelets adherent onto fibrinogen exhibited a 2.5-fold higher Src pY418 activity than Leu33 platelets after incubation for 20 min (p<0.01). Presence of Mn2+ (0.5 mM) in suspended Leu33 platelets stimulated their Src pY418 activity in an extent comparable to that of platelets adherent onto fibrinogen, while addition of Mn2+ (0.5 mM) to platelets adherent onto fibrinogen yielded a 3.5-fold increase in Src pY418 activity (p<0.05). Increase of the Mn2+ concentration (2 mM) raised the Src pY418 activity 1.5-fold, as compared to 0.5 mM Mn2+ (p<0.05). In parallel experiments with both HPA-1 isoforms of αIIbβ3, Pro33 platelets adherent onto fibrinogen in the presence of 0.5 mM Mn2+ revealed a 2.5-fold higher Src pY418 activity than Leu33 platelets after 5 min (p<0.05). This difference further increased upon prolonged adhesion for 10 or 20 min with a 5-fold increase after 40 min (p<0.01). The concentration of immobilized fibrinogen (10 or 100 μg/ml) had no influence on this effect. Addition of abciximab completely abolished the Src pY418 activation. Upon exposure to abnormal (5000 s−1) but not physiological (500 s−1) shear rates for 2 or 5 min, Pro33 platelets adherent onto 100 μg/ml fibrinogen exhibited a 2- or 2.5-fold higher Src pY418 activity than under static conditions (p<0.05 or 0.02, respectively). Under the same conditions, the Src pY418 activity of Pro33 platelets was 2-fold higher than that of Leu33 platelets (p<0.05). Again, different concentrations of fibrinogen (10 μg/ml and 100 μg/ml) did not affect these results. In comparison to Src (pY418), phosphorylation of FAK (pY397) increased slower both in Leu33 and Pro33 platelets adherent onto fibrinogen, when exposed to a shear rate of 5000 s−1 for 10min. Both isoforms (Leu33 or Pro33) exhibited a significantly higher FAK pY397 activity than under static conditions (3-fold increase, p<0.05). The Pro33 variant of αIIbβ3 showed a higher FAK pY397 activation than the Leu33 isoform (p<0.05). Again, abciximab completely blocked both the Src and FAK activation not only under static conditions but also upon exposure to shear. Conclusion: Our observations indicate that the HPA-1 polymorphism of αIIbβ3 has a considerable impact on the integrin-mediated outside-in signaling. The significantly higher Src (pY418) and FAK (pY397) activities of Pro33 platelets adherent onto fibrinogen under static and flow conditions are in agreement with the contention that the Pro33 (HPA-1b) isoform of αIIbβ3 is indeed a prothrombotic integrin variant. Disclosures: No relevant conflicts of interest to declare.

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Viscoelasticity and Drilling Fluid Performance

Volume 5: Materials Technology; Petroleum Technology ◽

10.1115/omae2014-23908 ◽

2014 ◽

Cited By ~ 2

Author(s):

John Lee ◽

Ahmadi Tehrani ◽

Steve Young ◽

Christine Nguyen

Keyword(s):

Steady State ◽

Viscoelastic Properties ◽

Xanthan Gum ◽

Drilling Fluid ◽

Polymer Concentration ◽

Shear Thinning ◽

Drilling Fluids ◽

Fluid Viscosity ◽

Field Equipment ◽

The Impact

Viscoelastic properties of drilling fluids are not often measured due to a lack of understanding of their impact on fluid performance as well as a lack of field equipment suitable for such measurements. A study has been conducted recently to evaluate the viscoelastic properties of xanthan gum and invert drilling fluids and their impact on barite suspension quality and rheology. Both a Brookfield YR-1 rheometer and a Bohlin Gemini 150 rheometer were used to generate data for comparison. The impact of viscoelasticity on steady-state rheology, thixotropy and shear thinning was evaluated using a multi-speed rheometer. A soon-to-be-adopted API recommended procedure was used to measure the barite sag tendency under dynamic conditions. Aqueous solutions of xanthan gum showed that viscoelasticity, shear thinning and thixotropy increased with increasing polymer concentration. When the solutions were weighed up with barite, they became more viscoelastic, slightly more thixotropic, but less shear thinning. Proper suspension of barite was observed at a xanthan gum concentration of 2 lb/bbl without any other additives. Compared to xanthan-barite suspensions, invert drilling fluids of similar density exhibited a greater viscoelasticity but less thixotropy and shear thinning. Treatment of invert drilling fluids with viscoelastic polymers resulted in a further enhancement of viscoelasticity and thixotropy, but a slight deterioration in shear thinning. Barite suspension quality showed a certain degree of correlation with viscoelasticity as well as steady-state rheology; however, these properties were temperature dependent for invert drilling fluids. Hydraulic analyses indicated that viscoelastic additives can impact fluid viscosity thus affecting pressure loss, equivalent circulating density and hole cleaning. Viscoelasticity enhancement may be used to improve barite suspension quality under certain conditions, but its impact on hydraulics must be carefully considered.

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Evolution of the viscoelastic properties of painting stratigraphies: a moisture weathering and nanoindentation approach

Heritage Science ◽

10.1186/s40494-021-00552-x ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Mathilde Tiennot ◽

Davide Iannuzzi ◽

Erma Hermens

Keyword(s):

Mechanical Properties ◽

Relative Humidity ◽

Cultural Heritage ◽

Mechanical Behaviour ◽

Viscoelastic Properties ◽

Viscoelastic Behaviour ◽

Storage And Loss Moduli ◽

Heritage Studies ◽

Paint Films ◽

The Impact

AbstractIn this investigation on the mechanical behaviour of paint films, we use a new ferrule-top nanoindentation protocol developed for cultural heritage studies to examine the impact of repeated relative humidity variations on the viscoelastic behaviour of paint films and their mechanical properties in different paint stratigraphies through the changes in their storage and loss moduli. We show that the moisture weathering impact on the micromechanics varies for each of these pigment-oil systems. Data from the nanoindentation protocol provide new insights into the evolution of the viscoelastic properties dsue to the impact of moisture weathering on paint films.

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