Properties Of Water-based Drilling Fluids Research Articles

Laponite-polymer composite as a rheology modifier and filtration loss reducer for water-based drilling fluids at high temperature

In the process of deep oil and gas drilling, high temperature and high amounts of salt will greatly deteriorate the rheological properties of water-based drilling fluids (WBDFs), increase the fluid loss of drilling fluids, and seriously threaten the safety of operations. It is urgent to develop new high-temperature and salt-resistant drilling fluid additives. In this study, a novel organic-inorganic polymer nanocomposite (P-RD') was synthesized by combining laponite and polymer, and its chemical structure and properties were characterized and evaluated by various experimental methods. The results show that P-RD' forms a spatial network structure in aqueous solution, and has good clay adsorption capacity and pore and crack sealing ability. At 180 °C and 15 wt% NaCl, it has good rheological stability to WBDFs, the American Petroleum Institute (API) filtration loss is only 7.1 mL, and the high temperature and high pressure (HTHP) filtration loss is controlled at 29.2 mL. P-RD' has dual functions, which can effectively strengthen the temperature and salt resistance of WBDFs, and is expected to be used as a rheology modifier and filtration loss reducer in high-temperature deep well drilling.

Carboxylated cellulose nanocrystals as environmental-friendly and multi-functional additives for bentonite water-based drilling fluids under high-temperature conditions

During the oil and gas drilling engineering, the selection of drilling fluids must take account of the technical and environmental factors. This study investigated the effectiveness of carboxylated cellulose nanocrystals (denoted as CNCs) as environmentally friendly additives for improving the rheological, filtration, and inhibitive properties of water-based drilling fluids (WBDFs). CNCs used in this study were modified by carboxylation reaction, displaying small size, negative surface charge, good colloidal stability, and prominent shear-thinning behavior. Experimental results indicated that BT/CNC suspensions had superior rheological properties, low fluid loss volumes, and effective inhibition, even at 140 °C. Microstructure analysis demonstrated that CNCs could attach to the surface of BT via hydrogen bond and ionic bond. CNCs, BT, and vicinal water molecules could form a stiff gel network, which had a strong resistance to flow under shear force, leading to a significant improvement in the rheological properties. Moreover, under the differential pressure, BT/CNC suspensions formed thin and less hydrophilic filter cakes with compact layered structure, thereby efficiently decreasing the fluid loss volume. Finally, due to the gel network and filtration ability, BT/CNC suspensions performed low water activity, which was beneficial for preventing the penetration of free water into the shales and borehole well. Thus, CNCs also exerted satisfactory inhibition on hydration and dispersion of BT and shales. As a result, CNCs showed great potential to be used as efficient, multi-functional, and environmentally friendly additives in WBDFs.

Effectiveness of cellulose polyanionic-based polymers on the measurement of rheological properties of water-based drilling fluids in high-pressure high-temperature fractured shale reservoirs

High-pressure, high-temperature fractured shale reservoirs are types of unconventional reservoirs that need proper drilling operations for adequate efficiency. Proper measurement of drilling fluid’s rheological properties is of importance for drilling operations that may increase the penetration rate on the one hand with proper design. Therefore, the success of drilling operations strongly depends on the proper design of drilling fluids. In this paper, we experimentally investigated the effect of potassium and sodium formate fluid on the rheological properties of drilling fluid for fractured shale core samples. The yield point and apparent viscosity for muds consisted of cellulose polyanionic and cellulose polyanionic-ultralow polymers higher than base muds. It indicates the effect of formate salts in increasing thermal stability. In addition, in polymer-based muds, more amounts of formate salts have been used, indicating the low fluid loss volume. Consequently, the shale recovery rate for potassium formate fluids is higher than sodium formate fluid.

Development of New Models to Determine the Rheological Parameters of Water-Based Drilling Fluid using Artificial Neural Networks

It is well known that drilling fluid is a key parameter for optimizing drilling operations, cleaning the hole, and managing the rig hydraulics and margins of surge and swab pressures. Although the experimental works represent valid and reliable results, they are expensive and time consuming. In contrast, continuous and regular determination of the rheological fluid properties can perform its essential functions during good construction. The aim of this study is to develop empirical models to estimate the drilling mud rheological properties of water-based fluids with less need for lab measurements. This study provides two predictive techniques, multiple regression analysis and artificial neural networks, to determine the rheological properties of water-based drilling fluid using other simple measurable properties. While mud density, marsh funnel, and solid% are key input parameters in this study, the output models are plastic viscosity, yield point, apparent viscosity and gel strength. The prediction methods have been applied on datasets taken from the final reports of two wells drilled in the Ahdeb oil field, eastern Iraq. To test the performance ability of the developed models, two error-based metrics (determination coefficient R2 and root mean square error have been used in this study. The current results support the evidence that MW, MF, and solid% are consistent indexes for the prediction of rheological mud properties. Both mud density and solid content have a relative-significant effect on increasing PV, YP, AV, and gel strength. The results also reveal that both MRA and ANN are conservative in estimating the fluid rheological properties, but ANN is more precise than MRA. Eight empirical mathematical models with high performance capacity have been developed in this study to determine the rheological fluid properties using simple and quick equipment such as mud balance and marsh funnel. This study presents cost-effective models to determine the rheological fluid properties for future well planning in Iraqi oil fields.

Advanced trends of shale inhibitors for enhanced properties of water-based drilling fluid

Water-based mud (WBM) is an environmentally acceptable drilling fluid. However, it makes shale to be prone to swelling owing to its interaction with active clays. Shale swelling makes drilling to be difficult, so, additives are added to inhibit shale swelling, and improve rheological and filtration properties. The use of conventional additives particularly organic and inorganic compounds are not suitable at extreme conditions of drilling. Other materials like nanomaterials have emerged as promising alternatives used under such conditions. This review aims to highlight in detail the essential types of inhibitors and the evolvement of nanoparticles in enhancing drilling fluid properties.

Investigation of regulating rheological properties of water-based drilling fluids by ultrasound

Regulating rheological properties of water-based drilling fluids has always been a hot topic. This paper proposed a new method for regulating rheological properties of water-based drilling fluids by ultrasonic field. The experimental results showed that the ultrasound increased the viscosity and yield point of bentonite suspension by reducing the particle size of clay, destroying the network structure between clay particles, increasing the mud yield and the cation exchange capacity of bentonite, and promoting the hydration dispersion of bentonite. The change of rheological property showed a memory effect at room temperature and high temperature. Besides, the ultrasonic energy affected the network structure between clays and polymer chains, thus regulating the rheological properties of the bentonite-polymer system. For two types of drilling fluids investigated, the rheology of the poly-sulfonate drilling fluid was regulated by damaging the grid structure between additives and clays by low-power ultrasound and reducing the clay particle size by high-power ultrasound, while the rheology of the deep-water drilling fluid was mainly regulated by disentangling the spatial grid structure between additives. Additionally, ultrasound showed no effect on the lubricity, inhibition and stability of drilling fluids, which proved the feasibility of ultrasound to regulate rheological properties of water-based drilling fluids.

Performance of water-based drilling fluids for deepwater and hydrate reservoirs: Designing and modelling studies

In deepwater drilling, the properties of water-based drilling fluids change remarkably due to low temperature and high pressure, which have a significant effect on lost circulation, wellbore instability and the window between pore pressure and fracturing pressure. The present work investigates the influence of low temperature and high pressure on polymer and nanoparticle (boron nitride (BN)) based drilling fluids with an aim to improve their rheological properties and fluid loss control. The amplitude and frequency sweep tests were conducted to understand the viscoelastic nature of the samples. The amplitude sweep tests confirmed the structural stability of the designed fluid within the studied sweep frequency. The study reveals that storage modulus (Gʹ) and loss modulus (Gʺ) of the samples are enhanced with increasing concentration of BN nanoparticles. Their viscoelastic range also increases due to the intermolecular interaction within the structure of the fluid in the presence of the nanoparticles. Within the linear viscoelastic range (LVER), all the samples show the dominance of elastic modulus than viscous modulus which delineates the solid-like behaviour. The results of rheological tests of drilling fluid containing BN nanoparticles indicate a significant reduction in plastic viscosity (PV), yield point (YP) and apparent viscosity (AV). The rheological studies conducted at different temperatures (from 10 °C to −5 °C) and pressures (from 7.8 MPa to11 MPa) reveal the minimum effect of pressure and temperature on the rheology of samples, which are desirable for their applications in hydrate and deepwater drilling. The filtration loss experiments conducted at 30 °C and 0.69 MPa show a large reduction in fluid loss volume (60.6%) and filter cake thickness (90%) for the sample with 0.4 wt% BN nanoparticles compared to that of the sample without nanoparticles. The filter cake permeability is also in the favourable range with 0.008 mD which shows a 94% reduction compared to the sample without nanoparticles. A regression model was developed to mathematically describe the experimental results, which demonstrates a good fitting with the statistical data of fluid loss volume, thickness and permeability of the filter cake.

Application of silica (SiO2) nanofluid and Gemini surfactants to improve the viscous behavior and surface tension of water-based drilling fluids

Further studies into drilling fluids especially to reduce the use of oil and synthetic-based drilling fluids are ever-growing due to their contributions to environmental pollution. This study, therefore, attempts to evaluate the thermal, viscosity, surface tension, and filtration loss properties of water-based drilling fluids (WBDFs) upon the addition of Gemini surfactant-silica nanofluid. This surfactant-nanofluid was formed by dissolving silica nanofluid in the surfactant solution, and ultra-sonication was used to attain homogeneity. Characterization of the Gemini surfactant-silica (SiO2) nanofluid was done by Fourier Transform Infrared Spectroscopy (FTIR). The viscosity, surface tension, and filtration loss properties were studied using the rheometer, tensiometer, and low-pressure, low-temperature (LPLT) filter press respectively. The experimental results showed that Gemini surfactants contributed to the highest increase in drilling fluid viscosity compared to a conventional surfactant. Also, when combined with silica-nanoparticles showed better thermal stability with an 11% average change in viscosity with increasing temperature and a decrease in surface tension and filtration loss both showing a 17% and 12% decrease respectively.

Enhancement of Filtration and Rheological Properties of Water-based Drilling Fluid Prepared using Nigerian Ohia Bentonite and Local Additives

Enhancement of Filtration and Rheological Properties of Water-based Drilling Fluid Prepared using Nigerian Ohia Bentonite and Local Additives

Enhancing the Rheological Properties of Water-Based Drilling Fluid by Utilizing of Environmentally-Friendly Materials

Recently, many materials have shown that they can be used as alternatives to chemicals materials in order to be used to improve the properties of drilling fluids. Some of these materials are banana peels and corn cobs which both are considered environmentally- friendly materials. The results of the X-ray diffraction examination have proved that the main components of these materials are cellulose and hemicellulose, which contribute greatly to the increasing of the effectiveness of these two materials. Due to their distinct composition, these two materials have improved the rheological properties (plastic viscosity and yield point) and reduced the filtration of the drilling fluids to a large extent. The addition rates used for each of the two materials (banana peels and corn cob) are 1%, 2%, 3%, 4%, 5% and 6%. As regard to banana peels, the results have shown that there is a direct correlation between the addition ratios, the increase in the rheological properties (plastic viscosity and yield point), and the decrease in filtration The corn cob has shown the same results. Also, 0.01% increase in the pH value was observed when adding a corn cob, while adding banana peels showed the opposite, as adding them led to 0.02% decrease in the pH value. Among the other properties that have been studied is density, as it has been noticed that there is no significant effect of these two materials on the density of drilling fluid. Moreover, the performance of these two materials has been compared with the PAC polymer. This research suggests that the possibility of moving towards corn cob and dried banana peels as additives for biodegradable drilling fluid. Apart from being environmentally friendly, the choice of using them is considered economically more efficient than other chemical additives. By all accounts, the above materials are an increasingly rational choice for moving forward for an environmentally friendly oil industry.

An investigation of the effects of synthesized zinc oxide nanoparticles on the properties of water-based drilling fluid

The deterioration of drilling fluid properties during deep drilling causes problems like inefficient cutting removal, fluid invasion, and shale swelling, which increases non-productive time (NPT) and cost. Recently nanoparticles (NPs) based drilling fluid are introduced to address these impediments since these particles prove their advantages in different stages of petroleum exploration and recovery. Previous developments are concerned with the use of commercial zinc oxide (ZnO) NPs in inorganic KCl salt-based drilling fluid, although application of KCl in drilling fluid arouses environmental complications. In this study, ZnO NPs prepared in the laboratory are used in water-based drilling fluid (WBDF) to assess the effect of nanoparticles on the properties of drilling fluid at two temperature conditions of 40 °C and 80 °C. A base mud is formulated, and ZnO NPs with five different concentrations of 0.05, 0.1, 0.5, 1.0, and 2.0 wt% are mixed with the base mud. The experimental analysis shows that NPs improve the rheological properties of WBDF. When the concentration of NPs was 0.1 wt%, the yield point increased by 61.54% at 40 °C, and when the concentration of NPs was 0.05 wt%, the yield point increased by 60% at 80 °C. Besides, when the concentration of NPs is 0.05 wt%, 10-sec gel strengths are enhanced by 25% and 50% at 40 °C and 80 °C, respectively. The API low-pressure low-temperature (LPLT) filter volume is not significantly affected by the addition of NPs in WBDF. However, mud cake thickness continuously reduces with the increase of NPs concentrations. This result reveals that a superior rheological improvement is achieved at low NPs concentration (0.05 wt%) at higher temperature.

Study of Rheological Properties of Water-based Drilling Fluid in the Well Strength (Using Alumina Nanoparticles)

Abstract Wellbore stability is of one of challenges in drilling industry. Shale formation is of one of the most problematic rocks during drilling because the rock has very low permeability and very small pores (nanometers). In this study, the viability of the Alumina nanoparticles in Water-Based Mud (WBM) is assessed. The effect of Alumina nanoparticles (alpha and gamma) as mud additives to improve the rheological properties in water- base drilling fluids are experimentally investigated. The Alumina nanoparticles has specific chemical and physical properties such as: high compressive strength, high hardness, high thermal conductivity, these properties improve the rheological properties of water base drilling fluid, reduce filtration loss and meet environmental regulations. The results of experiments indicated that Alumina nanoparticle are improving rheological properties such as: yield point (YP), gel strength (GEL 10s, Gel 10min) of water- base drilling, that can be used to improve the rheological and filtration properties of drilling fluids. The experimental data showed that, Alumina nanoparticle as a Nano additive, possessed excellent properties such as thermal stability, rheology enhancing, fluid loss control and lubrication. Also, it could plug the shale formation effectively and improve the pressure bearing capability of formation significantly. In addition, Alumina nanoparticles reduced 60% API/HPHT fluid loss by 60% in comparison with blank sample. The most striking feature is that shale integrity improved by Nano fluid between 60 and 70 percent in comparison with blank sample. Also, data experimental of CT Scan are shown that the filter cakes formed by each of the Nano-drilling fluid samples with alpha alumina and gamma alumina base are more cohesive and cause an integrated filter cake on the well.

Performance evaluation of esters and graphene nanoparticles as an additives on the rheological and lubrication properties of water-based drilling mud

In the practice of drilling horizontal, directional, and unstable well profiles, the friction produced by bit balling, wellbore instability, cavings, and dog-legs resulted in excessive torque and drag. The friction along with high torque and drag, which results from the drill string, casing, and wellbore contact, leads to pipe stucks, overpulls during tripping-outs, and even closure of the oil and gas well. Heat generated from metal contact between casing and drill string is the cause of wear of drill string and casing. Oil-based drilling fluids are identified to produce minimum friction and torque than that of water-based drilling fluid/mud (WBM). However, the use of oil-based drilling fluids is becoming obsolete due to stringent environmental regulations. Therefore, it is critical to identify and design a water-based drilling mud with lubricant additives that are environmentally friendly, cost-effective, and give better lubrication similar to oil-based and synthetic-based drilling fluid. The objective of this study is to investigate the effect of two additives PC60 (the product of the reaction of glycerol ​+ ​tall oil fatty acid) and graphene nanoparticles on the rheological and lubrication properties of water-based drilling fluid. All together total 14 drilling fluid samples have been prepared for the detailed analysis. Extensive experimental work has been done to study the effect of lubricant additives (PC60 and graphene nanoparticles) on the rheology and lubrication of various WBMs with different additive concentrations (1, 2, and 3% by volume) at 30, 60, and 90 ​°C. All samples were investigated for their rheology, viscoelastic behavior, and lubrication properties before and after hot rolling. The experimental data generated in this work have been successfully utilized to find various fitting parameter for the Bingham plastic rheological model, followed by a discussion on foaming tendency of the samples and effect of pH on the rheological stability of drilling fluid. Subsequently, a relationship between the coefficient of friction (in the presence of different lubricant additives in the mud) and rheological properties (plastic viscosity and yield point) of different drilling fluid samples have been proposed. • Rheological/lubrication properties of water-based drilling muds (WBMs) investigated. • The effect of two additives ester and graphene nanoparticles on WBM studied. • Ester-based WBMs shown better rheological performance/stability after hot rolling. • A relationship between coefficient of friction and rheological properties proposed. • Ester-based WBMs exhibit more foaming tendency than nano-graphene-based WBMs.

Effectiveness of Copolymer of Polymethylmethacrylate and Styrene as a Plugging Agent in Water-Based Drilling Fluids

In the development of shale gas, it is important to ensure the stability of the borehole wall. The stability of the borehole wall depends on the plugging ability of the drilling fluid, while the stabilizing ability of the drilling fluid is provided by adding the plugging agent to the fluid. Conventional plugging agents are characterized by a relatively high volume and do not allow one to effectively plug micropores and microcracks in shale rock. In this work, the PMMA-St copolymer was synthesized by emulsion polymerization of methyl methacrylate and styrene. The characteristics of the PMMA-St copolymer were studied by FT-IR, TGA, and phase analysis optical scanning methods. The results show that the size of PMMA-St nanoparticles ranges from 34 to 58 nm, and the average diameter is about 40.6 nm. The decomposition temperature of PMMA-St nanoparticles is 374.8°C, which indicates the good thermal stability of the copolymer. The PMMA-St nanoparticles have little affect on the rheological properties of water-based drilling fluids. The mud cake simulation method was used to evaluate the plugging performance of PMMA-St nanoparticles. The permeability of mud cake is 2.24 × 10-5 m2, which is close to the permeability of shale formation. When 0.5 wt % of the PMMA-St copolymer is added to the solution, the blocking rate is 70.27%. With increase in PMMA-St concentration, the blocking rate of the mud cake increases. The best stabilizing effect is achieved when the PMMA-St copolymer concentration is 1.0%. The results of the core experiments are consistent with the mud cake simulation, which indicates the excellent sealing ability of the PMMA-St copolymer. Therefore, PMMA-St nanoparticles can be effectively used as a plugging agent to ensure borehole stability in the shale formation.

Interaction of lubricants on the rheological and filtration loss properties of water-based drilling fluids

Drilling fluids show significant role in the success of drilling operations of oil and gas well. Lubricating and rheological properties are important for efficient drilling leading to improved oil/gas production. The current work deals with assessing the lubricating properties of 16 different water-based drilling fluids using five lubricants and scrutinizing their consequence on the rheology of the mud, filtration properties and mud cake thickness. Experiments are carried out at 90 °C by hot rolling the drilling fluids. After aging, the rheological, API HPHT filtration loss, and lubricating properties of mud are measured at ambient conditions. The results have been discussed in relation to the effect of lubricants on the recovery performance of oil and gas from reservoir. Increased lubrication provides enhancement in rate of penetration, with improved drilling efficiency into the oil and gas reservoir rock formation. The HPHT filter press test showed permissible fluid loss for all the drilling fluid systems containing lubricants with thin and impermeable filter cake formation. The thin mud cake and less fluid loss into the reservoir indicate less reservoir damage while drilling thus indicating enhanced recovery of oil and gas during production operation.

A New Comparative Evaluation for the Rheological and Filtration Properties of Water-Based Drilling Fluids Utilizing Sodium Salt of Linear and Cross-Linked Acrylate Polymer Hydrogels

Currently, polymers were applied as the most functional additives for optimizing the rheological behavior and filtrate volume control of water-based drilling fluids. To affirm this concept, the present work aims to prepare sodium salt of linear polyacrylic acid (NaLPAA), polyacrylamide (NaLPAM) and their cross-linked polymer hydrogels (NaCPAA and NaCPAM), in different ratios using N,N′-methylenebis(acrylamide), as a cross-linker, potassium persulfate and ascorbic acid as initiators. FTIR characteristic spectra, 1H NMR analysis, SEM micrographs and elemental analysis for the formed gels were employed to emphasize their consistence. TGA and TGA-DTG thermo-grams displayed that NaCPAA polymer hydrogel offered the highest thermal stability behavior. The swelling behavior of the prepared hydrogels was examined and demonstrated that CPAM showed the best behavior at pH = 4 (acidic medium). The rheological properties of the investigated water-based mud samples were studied at various temperatures. For sample containing 0.57% (2 g) of NaCPAA at ambient temperature, it showed the highest rheological behavior in which AV achieved the highest value at 118 cP, PV was recorded at 69 cP, and YP was detected at 99 lbf/100 ft2. At LTLP conditions, sample containing 0.57% of XC-polymer and 2.86% bentonite in its composition offered the most enhanced mud cake thickness at 4.2 mm. At HTHP conditions, the filtrate volume of sample containing 0.29% NaLPAA was detected at 35 mL and for sample containing 0.57% was calculated at 22 mL. In addition, the modified mud samples with the same recipe of NaLPAA and NaCPAA at different applied temperatures showed moderate rheological properties compared to the commercial XC-Polymer. Furthermore, NaCPAA manifested a reduction in the swelling properties of water-based mud system containing high amount of API bentonite (2.85%, 10 g) in which AV and PV were calculated at 30 and 17 cP, respectively. In addition, YP was recorded at 22 lbf/100ft2. So, it could be used as a thinner for water-based bentonite mud systems.

Experimental Investigation of Aloe-Vera-Based CuO Nanofluid as a Novel Additive in Improving the Rheological and Filtration Properties of Water-Based Drilling Fluid

SummaryDrilling technology in petroleum engineering is associated with problems such as high fluid loss, poor hole cleaning, and pipe sticking. Improvement of rheological and filtration properties of water-based drilling fluids (WDFs) plays a major role in resolving these drilling problems. The application of nanotechnology to WDF in the recent past has attracted much attention in addressing these drilling operations problems. In the present work, we investigate the application of natural aloe vera and CuO nanofluids combined as an additive in WDF to address the drilling problems. The nanofluids of three different concentrations of CuO nanoparticle (0.2, 0.4 , and 0.6 wt%) with aloe vera as a base fluid are prepared for this study by adopting a two-step method. The prepared nanofluids are characterized by their particle size and morphological characteristics. Conventional WDF (DF.0) is synthesized, and the prepared aloe-vera-based CuO nanofluid is added to the WDF to prepare nanofluid-enhanced water-based drilling fluid (NFWDF) of different concentrations of nanoparticles, namely, 0.2 , 0.4, and 0.6 wt%. The prepared drilling fluid mixture is then characterized for its rheological and filtrate loss properties at various temperatures. Thermal stability and aging studies are performed for both WDF and NFWDF. The experimental results are then modeled using rheological models. The results reveal that aloe-vera-based CuO nanofluids improve the thermal stability and rheological properties of drilling fluid and significantly decrease the American Petroleum Institute (API) filtrate. Viscosity for WDF shows an approximately 61.7% decrease in heating up to 90°C. Further, the hot roll aging test causes a 63% decrease in the viscosity of WDF at 90°C. However, the addition of aloe-vera-based CuO nanofluids is found to aid in recovering the viscosities to a great extent. The fluid loss values before hot rolling are observed to be 6.6 mL after 30 minutes, whereas fluid loss values for the NFWDFs are found to be 5.9, 5.4, and 4.6 mL, respectively. The fluid loss value after hot rolling for the WDF is found to be 10.8 mL after 30 minutes, whereas fluid loss values for the NFWDFs are found to be 9.2, 8.5, and 7.7 mL, respectively. The rheological performance data of NFWDF project a better fit with the Herschel-Bulkley model and suggest improvement in rheological and filtration properties. There has been limited research work available in understanding the impact of aloe-vera-gel-based nanofluids in improving the performance of WDFs through the improvement of its rheological and filtration properties. This study aims to exploit the property of native aloe vera and CuO nanofluids combined together to enhance the rheological and filtration properties of WDF by conducting the tests both before and after hot rolling conditions. This study acts as an important precursor for developing novel additives for WDF to improve its rheological and filtration properties. This study is also expected to benefit the industry and solve the major challenges in deep-well drilling operations and high-pressure and high-temperature (HPHT) drilling operations.

Effect of Iron Oxide Nanoparticles on the Properties of Water-Based Drilling Fluids

In recent years, several studies have indicated the impact of nanoparticles (NPs) on various properties (such as viscosity and fluid loss) of conventional drilling fluids. Our previous study with commercial iron oxide NPs indicated the potential of using NPs to improve the properties of a laboratory bentonite-based drilling fluid without barite. In the present work, iron oxide NPs have been synthesized using the co-precipitation method. The effect of these hydrophilic NPs has been evaluated in bentonite and KCl-based drilling fluids. Rheological properties at different temperatures, viscoelastic properties, lubricity, and filtrate loss were measured to study the effect of NPs on the base fluid. Also, elemental analysis of the filtrate and microscale analysis of the filter cake was performed. Results for bentonite-based fluid showed that 0.019 wt% (0.1 g) of NPs reduced the coefficient of friction by 47%, and 0.0095 wt% (0.05 g) of NPs reduced the fluid loss by 20%. Moreover, for KCl-based fluids, 0.019 wt% (0.1 g) of additive reduced the coefficient of friction by 45%, while higher concentration of 0.038 wt% (0.2 g) of NPs shows 14% reduction in the filtrate loss. Microscale analysis shows that presence of NPs in the cake structure produces a more compact and less porous structure. This study indicates that very small concentration of NPs can provide better performance for the drilling fluids. Additionally, results from this work indicate the ability of NPs to fine-tune the properties of drilling fluids.

Amine- and alcohol-functionalized ionic liquids: Inhibition difference and application in water-based drilling fluids for wellbore stability

Shale hydration is the main cause of wellbore instability during drilling using water-based drilling fluids (WBD). In this work, NH2- and HO-functionalized ionic liquids (ILs) were investigated for their performances on inhibiting the shale hydration, as well as their influences on the properties of WBD, using immersion and sedimentation tests, linear swelling test, hot-rolling dispersion test, rheological and filtration experiments. The mechanisms were identified by X-ray diffraction (XRD), zeta-potential and particle size distribution analyses, scanning electron microscopy (SEM) and related theoretical analysis. Evaluation experiment results showed that the NH2-functionalized IL had the best inhibition performance, followed by poly(propylene glycol)bis(2-aminopropyl ether), HO-functionalized IL and KCl. NH2-functionality was more favorable to shale inhibition than HO-functionality. When used in WBD, ILs could prevent viscosity building-up at high temperature, but cause filtration and inhibition failure, which could be mitigated when polyanionic cellulose (PAC) was added in WBD prior to inhibitors. Three critical observations helped elucidate the inhibitive mechanisms: the intercalation of cationic groups of ILs into the clay interlayers, the decrease of both interlayer spacing and double layer thickness. The NH2-functionalized IL allowed the smallest interlayer spacing and double layer thickness and therefore performed best in inhibition. The inhibition failure in WBD with ILs depended on two aspects: the consumption of ILs untimely and the filtration failure of WBD. PAC could decrease both of ILs’ loss within WBD and water loss toward shale, mitigating the WBD’s inhibition failure. Our work will facilitate the rational design of efficient and environmentally acceptable inhibitors and their rational applications in WBD for drilling shale formation.

The effect of nanoparticles with KCL salt on rheological and filtrate properties of water-based drilling fluid: experimental analysis

ABSTRACT The novel composition of bentonite mud was engineered to illustrate considerable viscosity properties under high temperature up to 150°C. In this research, the effect of nanoparticles, namely silicon dioxide (SiO2), titanium dioxide (TiO2), unfunctionalized and functionalized multiwall carbon nanotubes (UMWCNTs), (FMWCNTs) in different concentrations (0.01, 0.05, 0.1, and 0.5 wt. %) on the rheological and filtration attributes of bentonite mud was evaluated. Results indicated that yield point property increases with the increment of FMWCNTs concentrations up to 123% in 60°C. Filtration test presented favorite reduction and thinner mud cake were created by using FMWCNTs under normal and high temperature up to 150°C.