Cake Thickness Research Articles

Applicability of sawdust as a green additive to improve the rheological and filtration properties of water-based drilling fluid: an experimental investigation

Drilling fluid is essential to oil and gas drilling operations due to its diverse functionality. But the most commonly used drilling fluid additives are hazardous chemicals and are not biodegradable. As a result, the demand for environment-friendly additives has been raised to replace the hazardous chemical additives. Considering the rising interest toward green additive, this study examined the applicability of sawdust to be used as a biodegradable drilling fluid additive to improve the rheological and filtration properties of water-based mud. Sawdust was chosen for this study because of its high cellulose content, widespread availability, and low cost. Following the guidelines set by the American Petroleum Institute (API), we carried out laboratory experiments that encompassed three distinct concentrations of sawdust: sample 1 (with 0.25% sawdust), sample 2 (with 0.50% sawdust), and sample 3 (with 0.75% sawdust). The concentrations of sawdust were measured as a weight percentage of the total volume of the base water. Concentrations above 0.75% led to gelation issues. Results showed minimal impact on mud weight at 0.25% sawdust, while 0.50 and 0.75% concentrations caused slight weight reduction due to foam development. Plastic viscosity increased by 28.5, 42.8, and 71.4% for sample 1, sample 2, and sample 3, respectively, compared to the base mud. Sawdust-containing mud exhibited desirable gel strength and shear-thinning behavior. Moreover, sawdust significantly improved filtration properties by reducing fluid loss and mud cake thickness. Sample 2 (0.5% sawdust) performed well in terms of filtration properties. Mud cake permeability followed the trend: kBM>k0.75%sawdust>k0.25%sawdust>k0.50%sawdust\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${k}_{\\mathrm{BM}}>{k}_{0.75\\% \\mathrm{sawdust}}>{k}_{0.25\\% \\mathrm{sawdust}}>{k}_{0.50\\% \\mathrm{sawdust}}$$\\end{document}. Based on promising laboratory performance, lower concentrations of sawdust are recommended as a cost-effective and eco-friendly additive to enhance rheological and filtration properties of water-based drilling fluid systems.

Microfiltration of concentrated albumin solutions and the role of processing conditions on membrane fouling

Membrane processing is a subject of growing scientific and industrial interest as a valuable technology to replace conventional energy-intensive operations, but is hindered by the progressive decrease of permeate flux caused by membrane fouling. Although physico-chemical factors affecting membrane fouling have been widely investigated, less is known concerning the effects of processing conditions. Here, we focus on microfiltration of aqueous bovine serum albumin (BSA) solutions by using a novel miniaturized modular unit allowing to study both dead-end (DE) and crossflow (CF) filtration. Pure water flux measurements and Computational Fluid Dynamics (CFD) simulations were firstly performed to characterize the flow field inside the module. In presence of BSA, at the same transmembrane pressure (TMP) of 20 mbar and average pore size of 0.45 μm, a remarkable decrease in the fouling progression with time was found for CF with a peristaltic pump as compared to pressure-driven DE filtration. Furthermore, BSA concentration in the permeate was the same as in the feed for peristaltic CF, while negligible for DE. By either increasing transmembrane pressure or lowering membrane pore size, a stronger decay of permeate flux with time was observed. Scanning electron microscopy images of the membrane showed the presence of a thick surface cake layer under peristaltic CF, which became thinner by increasing TMP or reducing membrane pore size. Overall, the better performance of peristaltic CF can be interpreted in terms of reduced BSA residence time in the membrane, membrane deformability and formation of a permeable cake layer at lower TMP and larger membrane pore size. The innovative design of our filtration module and the combination of permeate flux and concentration measurements with CFD results and microscopy observations constitute the most significant aspects of this research work, which provides a multiscale picture of membrane fouling. The insight emerging from results aims to provide qualitative guidelines towards an optimal setting of processing conditions in membrane operations, which is highly needed to improve the membrane innovation pipeline.

Rice husk ash as a sustainable and economical alternative to chemical additives for enhanced rheology in drilling fluids.

Performance evaluation of drilling fluids is essential for a successful drilling project, as they not only remove drill cuttings but also prevent undesired penetration or outflow of formation fluids by sealing off wellbore walls. However, concerns have been raised about the use of chemical additives in drilling fluids due to their toxicity and non-biodegradability. To this end, agricultural waste materials are recognized as a promising alternative as they are cost-effective, environmentally sustainable, and can be used as a substitute for lost circulation materials. Rice husk ash (RHA) has become popular as an additive due to its renewable characteristics, including its large surface area, silica content, and microporous structure. This research article explores the rheological properties of drilling fluid with RHA as a filter control medium. The results showed that increasing concentrations of RHA in the drilling mud significantly improved its rheology, particularly at higher concentrations (15 and 20 wt.%). The addition of RHA modified the filtration and rheological properties of the drilling mud, resulting in improved plastic viscosity, yield point, density, gel strength, and thixotropy. However, filter loss and mud cake thickness increased at elevated RHA concentrations. Furthermore, the pH test revealed that the mud's properties shifted toward the acidic region as the RHA concentration increased. The results indicate that RHA could be used as a sustainable and cost-effective alternative to conventional chemical additives with a positive environmental impact. This study may also provide valuable insights into the use of RHA in water-based bentonite mud and could serve as a guide for future research in the drilling industry.

Investigating the suitability of North Dakota fly ash as fluid loss reducing additive in densified water-based drilling fluid

Fluid loss circulation control during drilling operations is becoming more challenging as exploration moves from conventional to unconventional energy resources. The process of controlling filtrate loss during drilling operation necessitates the right design of drilling fluid that is capable to build an impermeable thin filter cake layer and permit a loss of a reasonable amount of filtrate volume into the formation. It is essential to understand the dynamics that play out between particle morphology of drilling mud additives to assess the sealing efficiency of the loss-reducing additives. As a result, a lot of materials were suggested as fluid loss-reducing materials, which also give thin filter cake thickness. This study investigates the suitability of a coal-fired plant waste (fly ash), as an alternative supplement for filtration agents to improve the quality of the filter cake layer that is built using ilmenite (FeTiO3) derived densified drilling fluid. The ilmenite-derived densified water-based mud samples containing 0, 1, 2, and 3 lb./bbl of fly ash were investigated. To gain an understanding of the pozzolanic influence of class C fly ash on ilmenite-weighted water-based mud, tests were conducted at reservoir conditions according to API specifications. The results from drilling fluid tests were benchmarked against the API standard range of values and contrasted with a control drilling fluid with no-fly ash added. It has been found that mud samples that include fly ash have better filtration properties. The openings in the filter cake were sealed by the amorphous structured fly ash particles, which created an impermeable filter cake. In Mud-4 and Mud-5, where the filtrate volume was reduced by 75% and 79%, respectively, the influence of particle size distribution to form a good sealant and a further reduction in filtrate loss was observed.

Revolutionizing shale drilling with potassium chloride-based natural deep eutectic solvent as an additive

Shale instability is a significant problem, accounting for approximately 70% of wellbore challenges during drilling operations. To address this issue, shale inhibitors are commonly added to drilling mud to stabilize the encountered shale formations. Ionic liquids and deep eutectic solvents have been recognized as effective shale inhibitors due to their environmental friendliness and effectiveness. However, despite their advantages, these solutions still lack full environmental sustainability, leading researchers to explore more natural alternatives like Natural Deep Eutectic Solvents (NADES). This study focuses on the synthesis and application of a NADES composed of Potassium Chloride (KCl) and glycerine, aiming to enhance the environmental profile and efficacy of shale inhibitors. The NADES was prepared with a 1:8 molar ratio at a temperature of 60 °C. Characterization analyses, including Fourier Transform Infrared and Thermogravimetric Analysis, confirmed the formation of bonds between –(OH) and Cl− and demonstrated the NADES's thermal stability up to 200 °C. Incorporating 3% NADES into water-based mud, prepared following API 13B-1 standards, resulted in significant improvements in mud rheology. Specifically, the addition of 3% NADES reduced filtrate volume by 14.2% and mud cake thickness by 19.2%. Furthermore, the 3% NADES exhibited remarkable inhibition of clay swelling by 69.23% and demonstrated a shale recovery rate of 58%. When compared with 3% KCl and 3% 1-ethyl-3-methylimidazolium chloride (EMIM-Cl), the NADES-based mud outperformed both in terms of efficacy. These findings were further supported by additional analyses, including d-spacing measurements (XRD), Zeta Potential, Surface tension, and Field Emission Scanning Electron Microscopy. Additionally, the rheological behavior of the NADES-based mud aligned with the Yield Power Law at both 25 °C and 100 °C. The study's findings contribute to the advancement of greener drilling practices and highlight the applicability of KCl-based NADES as a potential drilling fluid additive.

Eco-friendly drilling fluid: A study on the use of broad bean peels as a natural additive

Drilling fluid is an essential part of the oil and gas drilling process because it provides the drill bit hydraulic pressure, cools and lubricates the drill, and transports the drilled cuttings to the surface. However, using conventional drilling fluids can have a negative influence on the environment as well as high costs. In order to overcome these issues, experts have recently looked into the use of sustainable and natural additives in drilling fluids. The possibility of using broad bean peels, a frequently encountered agricultural waste, as a natural component in drilling fluid is examined in this study. Testing methods used to assess the effectiveness of broad bean peels as a rheological modifier in drilling fluid included rheological measures, filtration tests, and infrared spectroscopic studies. The results show there is a noticeable trend of increasing plastic viscosity from 7 to 14 and yield point from 3 to 13 as the concentration increased from zero to 8 g. The 10-s gel strength of the drilling fluid also increased from 4 to 23, and the 10-min gel strength increased from 5 to 30 in the same concentration range. Filtration tests showed that the addition of broad bean peels at a concentration of 2% by weight reduced the filtrate loss by 12%, indicating reduced in filter cake thickness. According to the findings, broad bean peels can improve the rheological characteristics of drilling fluid, decrease fluid loss, and provide significant insight into the chemical make-up of the peels that can be used to maximize their effectiveness as drilling fluid additives. According to these findings, broad bean peels might be a practical and long-term replacement for conventional drilling fluid additives, resulting in drilling operations that are more cost- and environmentally-conscious.

A novel star polymer for regulating fluid loss in oil-based mud under high temperature conditions

Oil-Based Mud (OBM) is a highly effective drilling fluid system for challenging wellbore conditions such as water-sensitive and high-temperature drilling operations. To minimize filtration loss and achieve thin filter cake, fluid loss control additives are essential. This study introduces a star polymer as an alternative to traditional additives like gilsonite or linear polymer. The star polymer was synthesized using Reversible Addition Fragmentation Chain Transfer polymerization (RAFT) with hydrophilic and lipophilic monomers and crosslinkers. Mud properties such as rheology, fluid loss, mud cake thickness, and emulsion stability were evaluated for OBM and compared with commercially available fluid loss control additives at simulated downhole pressure and temperatures. Spectroscopy and thermogravimetric analysis were used to determine the chemical architecture and thermal stability of the star polymer. The results showed that the star polymer demonstrated thermal stability up to 225 °C, resulting in a small amount of fluid loss volume and ultra-thin filter cake for OBM systems with mud weight at 10.5 ppg and 13.4 ppg. Furthermore, the star polymer improved emulsion stability without significantly affecting plastic viscosity (PV), unlike commercially available fluid loss control additives. The results were consistent for both diesel and synthetic oil-based mud systems.

Enhancing thermal stability and filtration control for water-based drilling fluid using viscosifier polymers and potassium chloride additives

Drilling operations conducted under high-pressure and high-temperature conditions present significant challenges for modern drilling advancements. Downhole temperatures can significantly impact the stability of water-based mud (WBM) properties, leading to costly issues and non-productive time resulting from drilling instabilities. To mitigate these issues, it is crucial to employ high-temperature-resistant additives in such operations. This study aimed to examine the influence of temperature on the stability of commonly used polymer types in water-based mud drilling operations. A series of laboratory experiments were conducted to investigate changes in normal mud properties following exposure to temperatures ranging from 79 to 350 °F. Two different mud polymers were used, including two viscosifier polymers (Flowzan - type A and Xanthan gum - type B), with varying concentrations of potassium chloride (KCl). Rheological analysis revealed that Polymer A exhibited superior performance as most mud properties, including viscosity, yield point, and gel strength, were significantly affected at different temperatures. However, plastic viscosities fell below the minimum recommended range of 8 cP for both polymers. At 250 °F, Polymer A's apparent viscosity of WBM was enhanced by 87%, 100%, and 120% with 3%, 5%, and 7% concentrations of KCl, respectively. For Polymer B, at 200 °F, it was improved by 118%, 112%, and 106%. The addition of KCl to the viscosifier polymers enhanced the thermal stability of the drilling fluid within the operating temperature range of 250–350 °F. Gel Point (10-min) remained below the recommended 35 lb/100 ft2 for all KCl concentrations of both polymers, while Gel Point (10-s) remained below the recommended 15 lb/100 ft2 for temperatures above 200 °F. Three other polymers were studied for filtration control without any KCl concentration, namely Bio Pac (type C), Mil Pac Xlo (type D), and Perma Loss (type E). Although API fluid loss remained below the recommended 15 cm3 for all the polymers, filtration control, and cake analysis demonstrated that Polymer C exhibited superior performance compared to the others. It also displayed thermal stability and cake thickness below the recommended 0.1 in up to temperatures below 250 °F. A novel sinusoidal correlation function is fit to experimental data, which can be used for training machine learning approaches.

Eco-Friendly Drilling Fluid: Calcium Chloride-Based Natural Deep Eutectic Solvent (NADES) as an All-Rounder Additive

Designing an effective drilling mud is a critical aspect of the drilling process. A well-designed drilling mud should not only provide efficient mud hydraulics but also fulfill three important functions: enhancing mud rheology, inhibiting hydrate formation in deepwater drilling, and suppressing shale swelling when drilling through shale formations. Achieving these functions often requires the use of various additives, but these additives are often expensive, non-biodegradable, and have significant environmental impacts. To address these concerns, researchers have explored the potential applications of ionic liquids and deep eutectic solvents in drilling mud design, which have shown promising results. However, an even more environmentally friendly alternative has emerged in the form of natural deep eutectic solvents (NADES). This research focuses on an in-house-prepared NADES based on calcium chloride and glycerine, with a ratio of 1:4, prepared at 60 °C, and utilizes it as a drilling mud additive following the API 13 B-1 standards and checks its candidacy as a rheology modifier, hydrates, and shale inhibitor. The findings of the study demonstrate that the NADES-based mud significantly improves the overall yield point to plastic viscosity ratio (YP/PV) of the mud, provides good gel strength, and inhibits hydrate formation by up to 80%. Additionally, it has shown an impressive 62.8% inhibition of shale swelling while allowing for 84.1% improved shale recovery. Moreover, the NADES-based mud exhibits a 28% and 25% reduction in mud filtrate and mud cake thickness, respectively, which is further supported by the results of XRD, zeta potential, and surface tension. Based on these positive outcomes, the calcium chloride–glycerine NADES-based mud is recommended as a versatile drilling mud additive suitable for various industrial applications. Furthermore, it presents a more environmentally friendly option compared to traditional additives, addressing concerns about cost, biodegradability, and environmental impact in the drilling process for an ultimate global impact.

New application for Micromax in aqueous drilling fluids as a hydrogen sulfide scavenger

The release of hydrogen sulfide (H2S) during drilling operations endangers workers' health and safety while also causing corrosion-related equipment damage. Various H2S scavengers have been used, but researchers are still looking for an optimal and feasible scavenger. Micromax (manganese tetroxide, Mn3O4), which has high oxidation and absorption capabilities with a high manganese oxide content, may effectively scavenge H2S. This study aimed to address the potential of using Micromax as a scavenger for H2S in aqueous drilling fluid. The study investigated the impact of Micromax addition on the drilling fluid rheology, filtering behavior, alkalinity, and corrosion propensity. The experiments were performed for a base drilling fluid without scavengers and with two commercial scavengers (i.e., triazine and SourScav®), which serve as benchmarking references. The findings showed that Micromax increased the scavenging capacity of the fluid by 706.6%, which was about 4 and 5 times higher than those of triazine and SourScav, respectively. Micromax and commercial scavengers did not impair the drilling fluid's rheology, but they slightly increased the formed filter cake thickness. Micromax and triazine maintained the pH of drilling fluids at a safe level above 10, which is required in a sour environment, unlike SourScav, which reduced the pH to a critical value of 7.9. Micromax and the other two commercial scavengers demonstrated noncorrosive characteristics with nearly zero corrosion rate. For the first time, the present work demonstrated the potential application of Micromax as a low-cost H2S scavenger with competent mud properties for effective and safe drilling operations.

SDBS-Induced Dispersion Effect of High-Rank Coal Fines to Inhibit the Conductivity of Propping Fractures

Coal fines are commonly produced in the form of aggregates during the development of coalbed methane (CBM), which significantly restricts the well productivity. Specifically, the reunion state of coal fines plays a key role in impacting the conductivity of propping fractures after fracturing. In this work, the anionic surfactant sodium dodecyl benzene sulfonate (SDBS) was selected to control the reunion state of coal fines. Visualized simulations of coal fines’ transport behavior in proppants with different particle sizes were carried out under low constant pressure based on sand pack experiments. Moreover, the characteristics of coal fine filling and production in propping fractures were obtained. The results indicate that SDBS has a dispersion effect on coal fine aggregates in the KCl fracturing fluid, with an average reduction of 36% in particle size. There is a positive correlation between the proppant size and the permeability coefficient of propping fractures. Coal fines reduce the permeability coefficients obviously, which first rapidly decrease and then slowly reach a stable stage. In the first stage, the changes of permeability coefficients are affected by the relative particle sizes of the proppant and the coal fine, which is consistent with the classic 1/3 sealing mechanism. In the second stage, SDBS increases the amount of coal fines between the proppant pore throats, and the thickness of the filter cake formed from coal fines at the entrance of the propping fracture increases, resulting in the inhibition of fracture conductivity. Additionally, the output of coal fines is increased dramatically induced by SDBS. Finally, the inhibitory effect of SDBS on fluid production was verified by comparing the water production and coal fine content of two field wells CW # 1 and CW # 2. This study has guiding significance for the output and control of coal fines in low-pressure production of CBM wells.

Factors affecting the mechanical deep dewatering of sludge from wastewater treatment

Effects of pressure, dewatering time, and sludge cake thickness on the dewatering of wastewater sludge by the hydraulic dehydrator under the condition of adding CaO and FeSO4 were analyzed using the response surface method (RSM). It was found that when the parameters of pressure, dewatering time, and sludge cake thickness were changed, the trends of dewatering papermaking sludge and municipal sludge were similar under the condition of raw sludge with 3% CaO and 3% FeSO4. Specifically, the increase of pressure and dewatering time promotes the dewatering effect of wastewater sludge, and the thinner the sludge cake is, the better the dewatering effect. The water content can be affected by the change of pressure, dewatering time, and sludge cake thickness. In response surface analysis, the model F-value and coefficient of determination (R2) were 541.43 and 0.9986, respectively, indicating high significance and good correlation. In the model, the change of pressure, dewatering time, and sludge cake thickness affected the water content of paper sludge. Particularly, the increase of pressure and compression time enhanced the dewatering efficiency. The thinner the sludge cake was, the better the dewatering effect of paper sludge was.

X-ray Computed Tomography (CT) to Scan the Structure and Characterize the Mud Cake Incorporated with Various Magnetic NPs Concentration: An Application to Evaluate the Wellbore Stability and Formation Damage

The X-ray computed tomography method has provided unrivalled data about the characterization and evolution of the internal/external structure of materials by analyzing CTN and non-destructive imaging approach. Applying this method on the appropriate drilling-fluid ingredients plays a significant role in generating proper mud cake quality to stabilize wellbore, and avoid formation damage and filtration loss by preventing drilling fluid invasion into the formation. In this study, smart-water drilling mud containing different concentrations of magnetite nanoparticles (MNPs) was used to assess the filtration loss properties and formation impairment. Conventional static filter press, non-destructive X-ray computed tomography (CT) scan images and high-resolution quantitative measurement of CT number method were used to estimate the filtrate volume and characterize the filter cake layers, hence evaluating the reservoir damage through hundreds of merged images. The CT scan data were combined with the HIPAX and Radiant viewer digital image processing. The variation in CT number of mud cake samples under different concentrations of MNPs and without MNPs concentration were analyzed, and hundreds of 3D images as a cross-sectional profile were used. This paper highlights the importance of MNPs property in terms of minimizing filtration volume and improving mud cake quality and thickness, and hence improving the wellbore stability. From the results, a notable reduction of filtrate drilling mud volume and mud cake thickness to 40.9% and 46.6%, respectively, were recorded for drilling fluids incorporated with 0.92 wt.% of MNPs. However, this study asserts that optimal MNPs should be implemented to guarantee the best filtration property. As confirmed from the results, increasing the MNPs concentration beyond the optimal value (up to 2 wt.%) increased the filtrate volume and mud cake thickness by 3.23 and 33.3%, respectively. CT scan profile images show two layers of mud cake produced from water-based drilling fluids possessing 0.92 wt.% MNPs. The latter concentration was found to be the optimal additive of MNPs as it caused a decrease in filtration volume, mud cake thickness, and pore spaces within the structure of the mud cake. Using the optimum MNPs, the CT number (CTN) shows a high CTN and density material, and uniform compacted thin mud cake structure (0.75 mm). The produced thin mud cake layer reveals the precipitation or exchange of elemental/mineral composition during fluid-solid interaction. These results confirm that MNPs could help in avoiding or reducing the formation damage, driving away drilling fluid from the formation, and improving borehole stability.

Rheology and lubricity characteristics study at different temperatures using synthesized SnO2 nanoparticles in KCl free bentonite water base mud

Drilling mud is a major concerning element due to its high operational and economic impact on the drilling process. Various additives are introduced to enhance the efficiency of drilling fluid, but none of them could perfectly achieve their proposed efficacy in drilling operations. Researchers conceived several nanoparticles (NPs) in drilling fluid to dissolve this issue. In a singular instance, commercial tin oxide (SnO2) nanoparticles were utilized to analyze the influence of NPs on the rheological and filtration properties of inorganic KCl salt-based drilling fluid. However, the effect of SnO2 NPs on mud lubricity characteristics is not studied previously. However, due to the hazardous behavior of KCl, its use is very limited. Thus, we consider a KCl-free bentonite water-based mud to avoid any environmental damages from drilling operations. We also use SnO2 NPs that is synthesized in our laboratory by co-precipitation method. In addition to rheological and filtration properties, we also investigate the effect of NPs on mud's lubricity that was not considered in the previous study. Drilling fluid properties are measured at five different NPs concentrations of 0.10, 0.25, 0.50, 0.75 & 1.0 wt%, and at six different temperatures of 30, 40, 50, 60, 70, and 80 °C, while filtration properties are measured using API low-pressure low temperature (LPLT) condition. The addition of 0.1 wt% SnO2 NPs increases plastic viscosity, yield point, 10 s gel strength, and 10 min gel strength by 10%, 63%, 20%, and 14%, respectively. The maximum reduction in lubricity coefficient is found to be 14% at NPs concentration of 1.0 wt%. The NPs concentration of 0.5 wt% yielded a reduction in fluid loss and mud cake thickness by 8.1% and 34%, respectively. The study suggests that SnO2 NPs can be employed as an additive to improve the rheology, lubricity, and filtration properties of KCl-free bentonite water-based drilling mud.

Experimental investigation of magnetized-Cocos nucifera husk supported Citrullus lanatus peel microparticles as loss circulation agent in water-based drilling fluids

Lost circulation agents (LCAs) are usually added to drilling fluids (DFs) for fluid loss control into formation. This improves their filtration and rheological properties that are advantageous for well drilling operation. This study conducted experimental investigation of Cocos nucifera husk (CNH) and Citrullus lanatus peel (CLP) as fluid loss additive in water-based drilling fluids (WB-DFs). The effect of magnetizing 50 and 100 μm CNH and CLP microparticles (MPs) on the effectiveness of WB-DFs was investigated. Prototype core samples of uniform dimension were prepared from unconsolidated sandstone. The rheological, filtration, and petrophysical properties of samples were evaluated. Scanning electron microscope (SEM) and Fourier transform infrared spectrophotometer (FTIR) were used to characterize drilling fluid samples. Plastic viscosity (PV), gel strength (GS), yield point (YP), mud cake thickness (MCT), and mud density (MD) of magnetized CNH supported CLP microparticles in WB-DF (mMp-CNH-CLP-WB-DF) increased by 44.44%, 14.29%, 60.71%, 16.08%, and 26.64%, respectively, when the weight was increased from 5 g to 20 g. The filtrate volume (FV) reduced by 56.38% when the weight of CNH and CLP was increased from 5 g to 20 g. The drilling fluid was less alkaline at this condition. The formation damage (FD) percentage of mMp-CNH-CLP-WB-DF decreased from 12.57% to 7.31% at 100 psi and 100 µm particle size. SEM and FTIR showed smooth particle arrangement and presence of active functional groups. In conclusion, presence of mMp-CNH-CLP-WB-DF in WB-DF improved its suitability for use in drilling operation.

Investigating the Effectiveness of Tiger-Nut Oil (Cyperus esculentus L.) as Base Fluid in Synthetic-Based Mud

Due to the environmental effects and following the stringent regulations on drilling operations and the associated drilled cutting disposal, drilling fluid with less environmental impact are highly desirable over the conventional diesel based mud. This study seeks to determine the effect of ester derived from the oil of tiger nut using alkali catalyzed transesterification as base fluid for the formulation of a synthetic base mud. A total of four mud samples were formulated, three samples of 10ppg synthetic based muds were formulated using the ester at 70:30, 75:25, and 80:20 Oil-water ratio. The last mud sample was formulated using diesel as base fluid but at 75:25 Oil-water ratio. The fresh oil and its ester were characterized. The tiger nut ester was purified and the compositional analysis of the ester was carried out using the Fourier transform infrared spectrometry. The API recommended procedure was used to determine the mud samples density, rheological, filtration and emulsion properties. The result of the FTIR shows an absorption band at 1743.56 cm-1 indicates the presence of C=O of an ester. The result of the density of the fresh Tiger Nut Oil (TNO) and the ester are 0.98 and 0.87respectively, the viscosities are 25.7cp and 3.25cp respectively, the flash point and pour point are 173oC and -25oC, and 160oC and -15oC respectively. The plastic viscosity and yield point of the synthetic based mud ranges between 7.0cp to 16.0cp and 9.0lb/100sqft to 46.0lb/100sqft, while 9.0cp to 14.0cp and 20lb/100sqft to 27lb/l00sqft was measured for diesel oil-based mud. The filtrate volume and mud cake thickness for the synthetic based mud at 70:30, 75:25, and 80:20 oil-water ratio are 2.6ml and 1.2mm, 3.8ml and 1.1mm, 4.1ml and 1,0mm respectively, while 15.6 and 5mm were recorded for diesel oil based mud. The gel strength at 10sec and 10min of the synthetic based mud ranges between 6.0 and 11.0, while 7.0 and 8.0 were recorded for the oil based mud. These result shows that the ester based synthetic oil compared favorably with diesel in the formulation of drilling mud. From the result, it is observed that esterified TNO can as a base fluid for a synthetic base mud, but further research on the most cost effective way of producing the oil from tiger nut.

A Novel Ascorbic Acid Based Natural Deep Eutectic Solvent as a Drilling Mud Additive for Shale Stabilization

During drilling, almost 70% of wellbore instability issues result from the encountering of shale formations. Various additives such as salts, silicates, and polymers are used in water-based mud to enhance its shale-inhibition capability; however, such additives have certain limitations. Lately, ionic liquids and deep eutectic solvents (DES) have been used by various research groups as shale inhibitors in drilling fluid due to their biodegradability and efficacy. However, their popularity faded when a natural derivative of DES, i.e., Natural Deep Eutectic solvent (NADES), came into the picture. This research utilizes the in-house-prepared Ascorbic acid and Glycerine (AA:Gly)-based NADES as a drilling fluid additive for shale inhibition and compares its efficacy with counterpart inhibitors such as KCl, imidazolium-based ionic liquid, and Choline Chloride-based DES. The results show that 3% NADES improved the overall Yield point to Plastic viscosity ratio, with a 39.69% decline in mud cake thickness and a 28% decline in the filtrate volume of drilling mud. Along with improved drilling fluid properties, 3% NADES resulted in 77.77% shale inhibition and 87% shale recovery. Surface tension, d-spacing, zeta potential, and FESEM have been conducted to justify and elucidate the inherent mechanism behind the working of NADES as a drilling fluid additive and clay stabilizer. Thus, Ascorbic acid-based NADES is recommended as a potential non-toxic and cheap drilling fluid additive to improve drilling fluid properties and clay stability.

Rupture resistance of filter cake under static filtration using a novel experimental technique

A novel apparatus is used to quantify the filtration characteristics of water-based drilling fluids and rupture behaviour of external filter cake. Under static filtration, the filtration pressure (400 to 800 kPa), time (15 to 60 min), the particle size distribution of the weighing agent (D50: 11 to 136 µm) relative to the pore size distribution of the substrate (S50: 14 and 65 µm) and the type of weighing agent (CaCO3 or BaSO4) play an important role in governing the porosity, thickness, and the rupture resistance of filter cake. With an increase in D50 of mud, the normalised rupture resistance reduces by about 20% irrespective of the increase in the external filter cake thickness. Further, the viscosity of the filtrate increases with D50 indicating the retention of less xanthan gum in the filter cake. The denser barite particles form a thinner and tighter cake, which exhibits higher resistance to rupture.

Nano-CaCO3/AA-AM-AMPS cross-linked polymer core-shell structural nanocomposite as high temperature and high salt resistant filtration reducer in water-based drilling fluid

Effective filtration loss control under high temperature and high salinity environments is a great challenge in oil and gas drilling engineering. In this study, a core-shell structural nano-composite (CSNC) using precipitated nano-CaCO3 as the core material and cross-linked polymer between acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), acrylic acid (AA) and methylene-bis-acrylamide (MBA) as the shell was prepared by reverse emulsion polymerization. The structure of CSNC was characterized with Fourier infrared spectrum (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM) and particle size distribution analysis. The filtration control properties of CSNC particles were investigated in both aqueous solution and bentonite suspension with various contents of NaCl and CaCl2 respectively. The high temperature and high pressure (HTHP) filtration properties between CSNC and typical high temperature resistant filtration reducers were compared. The filtration controlling mechanism of CSNC particles were probed through zeta potential analysis, X-ray diffraction (XRD) analysis and filter cake morphologies observation. The results indicated that for the 4% w/v bentonite suspension treated with 3% w/v CSNC, the low temperature and low pressure (LTLP) filtration loss and filter cake thickness decreased by 84.2% and 76.1% respectively after thermal aging at 220 °C. When the bentonite suspension was contaminated with 30% w/v NaCl and 0.5% w/v CaCl2 respectively, incorporation of 1% w/v CSNC reduced the filtration loss by 72.5% and 86.9% after thermal aging at 200 °C. The core-shell structure, cross-linked structure, and salt tolerant sulfonic acid groups on the outer surface of CSNC in combination contributed to extraordinary filtration loss control under stringent high temperature and high salinity conditions.

Effect of Qusaiba shale formation on high-pressure high-temperature drilling fluids properties

Drilling operations encounter various problems, many of which affect mud quality and may delay or suspend drilling. Wellbore instability is one of the many problems that drilling engineers face while using water-based drilling fluids (WBDF). When WBDFs contact active clay minerals, they may hydrate and swell, damaging the wellbore. In this study, the effects of Saudi Qusaiba shale kaolin clay on WBDF characteristics were examined. Kaolin clay was used as drilled formation cutting at different concentrations (5, 10, 20, and 30 lb/bbl). A detailed study examined how kaolin clay affects mud. Drilling fluid density, alkalinity, rheological, viscoelasticity, filtration behavior, and particle settling were examined before and after adding kaolin clay particles. Experimentally, the higher temperature of the practical environment was simulated by bringing the temperature up to 250 °F. The results showed that there are two clusters of kaolin clay below and above 10 lb/bbl. Kaolin clay concentrations over 10 lb/bbl had a negative effect on fluid characteristics, whereas lower amounts had very little effect. The apparent viscosity (AV) increased by 3% and 16% at 5 and 10 lb/bbl, but it jumped to 72% and 89% after 20 and 30 lb/bbl of kaolin clay. At 20 and 30 lb/bbl of kaolin clay, the yield point (YP) increased by 213% and 377%, respectively. Time sweep indicated continual gel strength increase. The addition of kaolin clay reduced the alkalinity of the WBDF which allowed the clay minerals to swell. Furthermore, the filter cake thickness and filtration volume showed a gradual increment as the concertation of the kaolin clay increased due to the accumulation of the clay solid in the filter cake layer.