Swelling Inhibitor Research Articles

Performance Evaluation of 1-Butyl-3-Methylimidazolium Chloride as Shale Swelling Inhibitor

Shale instability due to hydration and swelling is an unavoidable problem during hydraulic fracturing or drilling with water-based fluids. In this study, 1-butyl-3-methylimidazolium chloride (BMIMCl) an ionic liquid was utilized as a clay swelling inhibitor. The performance of BMIMCl was evaluated by the bentonite plate soaking test and linear swelling test. FT-IR and zeta potential test was done to explain the swelling inhibition mechanisms. Moreover, XRD test was conducted for the characterization of bentonite (swelling clay). 2 wt.% BMIMCl reduced the swelling rate of bentonite by 19.38% while the conventional and mostly used inhibitor, 3 wt.% KCl reduced 13.84% compared with distilled water. These results showed that BMIMCl has better inhibitive properties than the most used clay stabilizer, KCl. This inhibitor showed better performance because of the presence of a hydrophilic head and hydrophobic tail in its structure. The hydrophilic positive head helped it to get adsorbed on the bentonite surface, forming hydrogen bonds, and reduced the surface negative charge. On the other side, the butyl chain may be made a hydrophobic shield that prevented water from entering into the interlayer space. The ability of BMIMCl to form bonds with bentonite and water was confirmed by FT-IR analysis. Therefore, BMIMCl has the potential to be an effective shale swelling inhibitor during drilling and hydraulic fracturing operations in the water-sensitive shale formation.

Okra mucilage as environment friendly and non-toxic shale swelling inhibitor in water based drilling fluids

Water-based muds (WBMs) cause severe formation damage during the drilling operation when interacting with clay-containing formations. To avoid clay swelling, it is common practice to add swelling inhibitors in WBMs. It is extremely important to have an understanding of the physicochemical interactions of such inhibitors with clay formation and their impact on drilling muds. The study reports the application of Okra mucilage as a clay swelling inhibitor. Okra mucilage was extracted from okra by heating it in distilled water at 40 °C temperature for several hours. Swelling inhibition was evaluated by conducting a linear swelling test, a capillary suction timer (CST), zeta potential, and particle size. Rheology and filtration experiments were conducted to evaluate the performance of Okra mucilage contained drilling muds. The experimental investigations showed the inhibition potential of Okra mucilage. The Okra mucilage reduced the clay swelling appreciably as compared to distilled water. Moreover, the Okra mucilage showed comparable performance to a commonly used clay stabilizer (KCl) used in the industry. It was observed that Okra mucilage reduced the fluid loss and provided a thin filter cake. The rheological properties were improved with the addition of Okra mucilage. The increase in clay particles and reduction in zeta potential showed the inhibition properties of the Okra mucilage. In addition, Okra mucilage reduced friction and provided lubricity. The proposed Okra mucilage could be a green and environmentally friendly alternative clay swelling inhibitor.

Ionic Liquids as Clay Swelling Inhibitors: Adsorption Study

Ionic Liquids as Clay Swelling Inhibitors: Adsorption Study

An efficient, cost-effective, and green natural extract in water-based drilling muds for clay swelling inhibition

Clay swelling is one of the major challenges of the oil and gas industry during the drilling operation. Water-based muds (WBM) are commonly used in drilling operations due to their low environmental footprint. The rheological properties, fluid loss control, and clay hydration play a crucial role in the selection of WBM. However, WBM can cause clay swelling in contact with clay material. For the first time, the present work reports the effect of Date palm leaves extract (DPLE) as a naturally occurring and environment-friendly green additive as a clay swelling inhibitor for water-based muds (WBM). The extensive evaluation including rheology, fluid loss, capillary suction timer (CST), zeta potential, X-ray diffraction (XRD), scanning electron microscope (SEM), and linear swelling tests were used to assess the clay swelling inhibition features of the DPLE. The outcomes revealed that the swelling control by DPLE was the function of its concentration. The 5% DPLE demonstrates the least linear swelling (62.3%) as compared to 2% DPLE (98.5%) Na2SiO3 (96.5%), and water (124.2%). The DPLE also influences and improves the rheology and deflocculation properties of the WBM. The proposed inhibition mechanism shows that the surface coating of DPLE resulted in the protection of bentonite clay and make it hydrophobic. Consequently, the affordability, environment friendliness, clay swelling control, and ease of access make the pertinency of DPLE in WBM extremely worthy.

Evaluation of novel microemulsion-based (O/W) drilling fluid with nonionic surfactant and shale interaction mechanisms

The increasing production of hydrocarbons from unconventional reservoirs, particularly water-sensitive formations, has led to the emergence of technologies necessary to maintain wellbore stability. The drilling fluid must always be adequate to the needs presented by such formations since serious problems may be generated due to inadequate drilling fluid planning. Microemulsions appear in this scenario with advantages over the traditional fluids already used by the industry due to their thermodynamic stability, ease of preparation, and is environmentally acceptable. This work aimed to evaluate the inhibition capacity of microemulsion-based drilling fluids comprised of nonionic surfactants and pine oil, environmentally friendly components, and never before assessed in the laboratory. Initially, a shale sample from a sedimentary basin in Northeastern Brazil was characterized using XRF, XRD, TGA, and DTA. The microemulsions, base of the drilling fluids, were formulated from a ternary phase diagram, in which a water/glycerol solution (1:1 by mass) was used as the aqueous phase, pine vegetable oil as the oil phase, and two nonionic surfactants, Ultranex NP100 and Alkest Tween 80 were used separately in the formulated systems. Potassium citrate (INIB1) and potassium sulfate (INIB2) were also used to inhibit the swelling of reactive formations. In order to evaluate the behavior of drilling fluids, rheology tests, filtrate loss, filtercake thickness, and permeability were considered. Finally, drilling fluid systems were tested for shale inhibition and dispersion capability. In addition to systems composed of INIB1 and INIB2, potassium chloride (KCl) (INIB3) was evaluated, and a system without a swelling inhibitor (SI). It was observed that the shale samples presented clay minerals from the smectite group, which represent a more significant interaction with water for swelling of hydratable formations. Drilling fluids showed rheological behavior following the Herschel-Bulkley model. There is a variability of interactions in the fluids concerning the concentrations of surfactant, oil phase, and swelling inhibitor, with more significant responses associated with increased surfactant concentration in the microemulsion. The drilling fluids showed a significant swelling inhibition, especially the fluid formulated from the surfactant Ultranex NP100 and INIB2, with a 6.9% swelling variation. Excellent results concerning dispersibility were also achieved, with the NP100_INIB1 fluid being the lowest dispersion of cuttings (0.075% and 0.215%). In general, the microemulsion-based drilling fluids efficiently inhibited swelling of the shale sample, showing good rheological and filtration behavior.

Characterization of nano based drilling fluid for shale swelling inhibition

Shale swelling is vital causing instability issues with water-based drilling fluids (WBDF). It happens because shale has reactive minerals causing swelling with water. Previously used inhibitors protected clay surface, but nanopores remained open. Physical plugging of nanopores is essential to improve swelling inhibition. Objective of this research is to identify a better shale swelling inhibitor. 0.1–1.1 wt% of Multi Walled Carbon Nanotubes (MWCNTs) is used to improve inhibition in bentonite wafers. MWCNTs is characterized by FESEM, TGA, and FTIR. Swelling inhibition, rheological, and filtration properties are determined upto 150 °C. MWCNTs based WBDF is also characterized by XRD to study MWCNTs effect on d-spacing. Rheological model study is performed. FESEM determined 94.5% purity, TGA confirmed thermal stability up to 904 °C, and FTIR found carbon bonds. MWCNTs has induced 57% swelling inhibition in comparison with base fluid. Rheological and filtration properties are improved potentially, that is, Rheology has improved 57% and filtration 55%. Drilling fluid samples are found following shear thinning and Bingham Plastic model with 0.933–0.97 R 2 and lowest RMSE values upto 100 °C. In future, MWCNTs can be used with other nanoparticles, polymers, and ionic liquids for swelling inhibition.

Machine learning approach to predict the dynamic linear swelling of shales treated with different waterbased drilling fluids

Oil and gas drilling contractors face many challenges during drilling, mainly related to wellbore instability. The water-based drilling fluids (WBDFs) are mixed with various swelling inhibitors; nevertheless, shale swelling could still take place. To quantify the swelling inhibition potential of WBDF, several laboratory experiments are usually carried out. These experiments are costly, time-consuming, and tedious. This study used machine learning techniques to predict the dynamic linear swelling of shale wafers treated with different WBDF containing different inorganic salts and silicates such as KCl, NaCl, CaCl2, sodium silicates, and aqueous alkali aluminosilicates (AAAS). An extensive experimental study was carried out to collect enough datasets to train machine learning models with different WBDF results. The swelling inhibition potentials were measured using a dynamic linear swell meter. All the WBDF solutions were tested on sodium bentonite clay wafers. The linear swell tests were run on each drilling fluid for 24 – 48 h. In addition to the linear swelling measurement, zeta potential and conductivities of all WBDF prepared with different concentrations were measured. ML techniques such as Artificial Neural Network (ANN), Decision Trees (DT), Random Forest (RF), and K Nearest Neighbor Algorithm (KNN) were utilized. ML models were trained on input parameters such as zeta potential, salt conductivity, salt concentrations, and elapsed time. The output of ML models was dynamic linear swelling in percentage. The results showed that the ANN technique could predict the linear swelling percentage as a function of the inputs, as mentioned above. ANN also proved to work better than the RF, DT, and KNN. Average Absolute Percentage Error (AAPE), Root Mean Square Error (RMSE), and Coefficient of Determination (R2) were used to measure the accuracy of the predicted model. In addition to the trained models, an explicit empirical correlation from the ANN model's fine-tuned weights and biases are also presented. The developed ANN model can efficiently measure the swelling potential of different WBDF and work best on the concentration of inorganic salts in WBDF ranging between 0.1 and 7 wt%.

Inhibition of swelling clays and consolidation of Itararé Sandstone using diaminoalkanes (DAA) and ethyl silicate (TEOS)

The conservation of stones containing swelling clay minerals such as montmorillonites is a challenging task. In this context, swelling inhibitors (DAA) were tested and a treatment based on consolidation with TEOS (ethyl silicate) was carried out on a sandstone containing swelling clay minerals: the Itararé Sandstone (commercial name). In this laboratory experiment, the inhibition of swelling, pore size and distribution, capillarity, colorimetric alteration, durability of treatments against the action of water, effectiveness of consolidation, and penetration depth were evaluated. Swelling inhibitors were effective in inhibiting the clay minerals from swelling. The consolidant, despite its effectiveness, altered the pore size and distribution and water absorption significantly, forming a very cracked gel, darkening the stone, reducing resistance to the action of water and presenting small penetration depth. When swelling inhibitors were applied before the consolidant, swelling inhibition also occurred, the porosity was less altered, the consolidant was less cracked, there was less chromatic modification and the sample became more resistant to the action of water. Therefore, this treatment proved to be more effective with fewer changes to the physical characteristics of the stone than the sole application of the consolidant.

Effects of imidazolium- and ammonium-based ionic liquids on clay swelling: experimental and simulation approach

Water-based fracturing fluids without an inhibitor promote clay swelling, which eventually creates wellbore instability. Several ionic liquids (ILs) have been studied as swelling inhibitors in recent years. The cations of the ILs are crucial to the inhibitory mechanisms that take place during hydraulic fracturing. Individual studies were carried out on several ILs with various cations, with the most frequently found being ammonium and imidazolium cations. As a result, the goal of this study is to compare these two cations to find an effective swelling inhibitor. A comparison and evaluation of the clay swelling inhibitory properties of tetramethylammonium chloride (TMACl) and 1-ethyl-3-methylimidazolium chloride (EMIMCl) were conducted in this work. Their results were also compared to a conventional inhibitor, potassium chloride (KCl), to see which performed better. The linear swelling test and the rheology test were used to determine the inhibitory performance of these compounds. Zeta potential measurements, Fourier-transform infrared spectroscopy, and contact angle measurements were carried out to experimentally explain the inhibitory mechanisms. In addition, the COSMO-RS simulation was conducted to explain the inhibitory processes and provide support for the experimental findings. The findings of the linear swelling test revealed that the swelling was reduced by 23.40% and 15.66%, respectively, after the application of TMACl and EMIMCl. The adsorption of ILs on the negatively charged clay surfaces, neutralizing the charges, as well as the lowering of the surface hydrophilicity, aided in the improvement of the swelling inhibition performance.

Capillary Suction Timer and machine learning techniques as tools for evaluating the performance of different shale inhibitors used in drilling mud

Drilling through shales with higher clay content is highly challenging with water-based drilling fluids. Numerous shale swelling inhibitors such as salts, polymers, and other chemical additives are used in drilling muds to stabilize shale formations. The inspection of the swelling inhibition capabilities of these additives is of utmost importance before its field application. Capillary Suction Timer instrument has been used to evaluate the shale inhibition performance of three categories of shale stabilizers for water-based drilling fluids. Each category of additive contains three different types of chemicals: salts (Potassium Chloride, Potassium Formate, and Choline Chloride), polymers (polyN-[3-(dimethylamino)propyl]methacrylamide, poly[2-(acryloyloxy)ethyl]trimethylammonium chloride and Polyvinylpyrrolidone) and ionic liquids (1-Butyl-3-methylimidazolium chloride and two other deep eutectic solvents). Capillary Suction Time for each chemical additive has been determined for various concentrations at room temperature. This test helps assess the clay swelling capability of the drilling mud in the presence of different additives at various concentrations. The Capillary Suction Time is dependent on the type and concentrations of chemical additive exhibiting a relative change in clay water interaction inhibition. The ionic liquids area significant category for clay swelling inhibition showing a minimum increase in Capillary Suction Time after 24 h. This indicates shale inhibition durability of the additive by resisting the water intake by clay. In addition, Fourier Transform Infra-Red and X-ray Diffraction techniques helped in characterizing the clay under consideration. The present work focuses on modeling the capillary suction time using machine learning algorithms. This technique provides a robust model for assessing the swelling capabilities of the drilling mud based on the concentration and types of additives. Of the different algorithms used, the Gradient Boosting algorithm provides the best model for capillary suction time estimation with an accuracy of 98%.

Preparation, performance and mechanism of 3-aminopropyltriethoxysilane modified graphene oxide as nano shale swelling inhibitor

Wellbore instability is a challenging technical problem in drilling operation, shale inhibitor can effectively inhibit shale hydration and dispersion, so as to stabilize the wellbore of shale. In this paper, graphene oxide was prepared by Hummer’s method, and modified by 3-aminopropyltriethoxysilane. The structure of modified graphene oxide was characterized using FT-IR and TGA, and the results showed that modified graphene oxide has been successfully prepared. The inhibitive performance was investigated by the linear swelling and hot-rolling tests, which shows the swelling rate of artificial core is reduced by 10.32% in 2.0% inhibitor solutions and the shale rolling recovery rate was reached 90.13% in 3.0% inhibitor solutions at the rolling condition of 120 °C × 16 h. Finally, the inhibition mechanism was studied, inhibitor can enter into the interlayer of shale and change the appearance of bentonite by physical and chemical interaction, and in that way achieve a good inhibition result.

Experimental Study on Preventing Formation Damage Due to Clay Swelling Caused by Water Based Drilling Fluid Using Aluminum Ion Based Clay Inhibitor

Formation damage is an unfavorable challenge that occurs during drilling. The present study reports applicability of aluminum complex (AC, the combination between Al ion of aluminum sulfate (AS) and ethylenediaminetetraacetic (EDTA)) as a permanent clay swelling inhibitor in water-based drilling fluids. That used to reduce formation damage in the near wellbore. This complex is an environmentally friendly and inexpensive additive in water-based drilling fluids (WBDFs) as a clay swelling inhibitor. Some experiments were performed in this study including free swelling test, bentonite sedimentation test, compatibility test, and core flood analysis. The results showed that AC solution can act properly as a clay swelling inhibitor at optimal concentration of AC around 5.4%wt. More than, compatibility test indicated that AC additive is compatible with other common additives in WBDF. The results show adding 8.1 wt.% of AC solution have lowest permeability reduction compared to other concentrations. More than, core flooding results showed AC solution can act as permanent clay inhibitor compared to KCl that is a temporary inhibitor. The AC solution performance was not much sensitive to salinity.

Preparation and Evaluation of Ammonium Adipate Solutions as Inhibitors of Shale Rock Swelling

This study aimed to evaluate the inhibitory effect of a series of ammonium adipate solutions (AASs) by using the linear expansion test, thermogravimetric analysis (TGA), and particle size distribution analysis, and to examine the underlying inhibitory mechanism. A series of AASs was prepared from adipic acid and amines as small-molecule inhibitors of oil shale rock swelling. They were then evaluated by the bentonite linear expansion test. The best one, namely, AAS-8 (synthesized with adipic acid and tetraethylenepentamine in a ratio of acid group to amine group of 1:2), was evaluated in a water-based drilling fluid. The linear expansion test showed that the linear expansion rate of AAS-8 was the lowest (59.61%) when the concentration was 0.1%. The evaluation of the drilling fluid revealed that AAS-8 had a strong inhibitory effect on the swelling of hydrated bentonite particles in the water-based drilling fluid and was compatible with carboxymethyl cellulose (CMC) and modified starch. The inhibition mechanism of AAS-8 was investigated using TGA and particle size distribution analysis, which demonstrated that AAS-8 might enter the clay layer and bind the clay sheets together by electrostatic adsorption and hydrogen bonding.

Surface-modified biopolymer as an environment-friendly shale inhibitor and swelling control agent

The efficiency of the oil well drilling process primarily depends on the shale inhibition features of the water-based mud (WBM). The current study describes the effect of surface-modified biopolymer swelling control and rheological properties of clay. The cellulose is a biopolymer with a huge surface area, eminent toughness, a prominent number of functional groups, and relatively non-toxic nature. The surface structure of cellulose gives the freedom to functionalize the surface with specific functionalities. Styrene-modified cellulose (MC) is used for the first time as an environment-friendly swelling inhibitor. The inhibition profile of the WBM was assessed by applying the % dispersion recovery test, shale inhibition stability test, and linear swelling test. MC added water-based mud (MC-WBM) demonstrated the best performance in the dispersion recovery test and 77.8% of the shales were recovered as related to 70.2% from unmodified WBM, 73.6% commercial shale inhibitor-WBM, 46.5% KCl (aq), and 24.7% from water. The bentonite clay shows 31% swelling in MC, while 37%, 41.6%, 61%, and 87% in commercial shale inhibitor, unmodified mud, KCl, and water respectively during the linear swelling test. Whereas the rheological properties of the MC modified drilling mud remain almost the same. To confirm the adsorption of MC on the surface of the clay, various characterization techniques such as Fourier transforms infrared spectroscopy (FTIR) analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results disclosed that MC blocks the nanopores on the shale surface that causes a prominent decrease in the swelling of bentonite clay. The anticipated swelling inhibition mechanism of the MC demonstrates that the MC carries functional groups that can interrupt the hydrogen bonding between water molecules and clay surfaces. Consequently, the clay surface is being protected against water-reactive action.

Preparation and Evaluation of Ammonium-Succinic Salts as Shale Swelling Inhibitor and Its Application in Water-Based Drilling Fluids

Preparation and Evaluation of Ammonium-Succinic Salts as Shale Swelling Inhibitor and Its Application in Water-Based Drilling Fluids

Preparation of Ammonium Oleic Acid Salts and Their Evaluation as Shale Swelling Inhibitors in Water-Based Drilling Fluid

Abstract In this paper, ammonium oleic acid salts (AOS) were prepared from oleic acid and amines and investigated as low molecular weight shale swelling inhibitors. First, the inhibitory effect of AOS was investigated using the linear expansion test of bentonite. The results show that the inhibitor prepared from oleic acid and tetraethylene pentamine with a molar ratio of 1:2 (AOS-8) has an excellent inhibitory effect on the hydration expansion of bentonite. The inhibitory effect of AOS-8 on bentonite was further investigated in subsequent work steps using various methods, including the linear swelling test of clay and particle distribution measurement. The results show that AOS-8 has superior performance in inhibiting hydration swelling and dispersion of bentonite. With 0.5% AOS-8, the swelling rate was reduced to 37.7%, and the particle size of bentonite in water could be controlled with AOS-8. Finally, the inhibition mechanism of AOS-8 was determined in detail by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). In water-based drilling fluid, AOS-8 is compatible with conventional additives. It can also significantly improve the lubricating capacity of the mud cake after ageing at 120°C.

Dicationic Surfactants as an Additive in Fracturing Fluids to Mitigate Clay Swelling: A Petrophysical and Rock Mechanical Assessment.

The interactions of clays with freshwater in unconventional tight sandstones can affect the mechanical properties of the rock. The hydraulic fracturing technique is the most successful technique to produce hydrocarbons from unconventional tight sandstone formations. Knowledge of clay minerals and their chemical interactions with fracturing fluids is extremely vital in the optimal design of fracturing fluids. In this study, quaternary ammonium-based dicationic surfactants are proposed as clay swelling inhibitors in fracturing fluids to reduce the fractured face skin. For this purpose, several coreflooding and breakdown pressure experiments were conducted on the Scioto sandstone samples, and the rock mechanical properties of the flooded samples after drying were assessed. Coreflooding experiments proceeded in a way that the samples were flooded with the investigated fluid and then postflooded with deionized water (DW). Rock mechanical parameters, such as compressive strength, tensile strength, and linear elastic properties, were evaluated using unconfined compressive strength test, scratch test, indirect Brazilian disc test, and breakdown pressure test. The performance of novel synthesized surfactants was compared with commercially used clay stabilizing additives such as sodium chloride (NaCl) and potassium chloride (KCl). For comparison, base case experiments were performed with untreated samples and samples treated with DW. Scioto sandstone samples with high illite contents were used in this study. Results showed that the samples treated with conventional electrolyte solutions lost permeability up to 65% when postflooded with DW. In contrast, fracturing fluid containing surfactant solutions retained the original permeability even after being postflooded with DW. Conventional clay stabilizing additives led to the swelling of clays caused by high compression and tensile strength of the rock when tested at dry conditions. Consequently, the rock fractures at a higher breakdown pressure. However, novel dicationic surfactants do not cause any swelling, and therefore, the rock fractures at the original breakdown pressure.

Sodium caseinate reduces the swelling of konjac flour: A further examination

Konjac flour can quickly swell and dissolve in a short time, leading to extremely high viscosity and easily agglomerative phenomenon. Such characters limit its application as ingredients in brewed foods and there is a high demand to restrict its swelling. Ethanol is usually adopted as a swelling inhibitor but it cannot be applied in the food industry. In this study, two types of milk (full-fat milk and low-fat milk) were selected and the swelling rates of konjac flour in these milk systems were measured. The results showed that the swelling rate of konjac flour significantly decreased. The konjac particles quickly cracked and dissolved in water within 3 min while only swelled in milk systems. To reveal which component in milk played a key role, we further studied the influence of the three components (lactose, whey protein isolate and sodium caseinate) on the swelling limitation of konjac flour. Sodium caseinate was found to be the strongest component than lactose and whey protein isolate in limiting the swelling of konjac flour. Our study revealed that casein was the crucial actor in inhibiting konjac flour swelling in milk and simulated milk system, indicating a new way to better control its swelling behavior in aqueous solution.

Cationic gemini surfactants containing biphenyl spacer as shale swelling inhibitor

The inhibition of shale from swelling and hydration is the primary concern in the drilling process of the oil and gas industry. In this study, the effect of two gemini surfactants having biphenyl spacer and different counterions (chloride and bromide) on rheology, filtration, and shale inhibition properties were investigated at different concentrations (0.05 wt%, 0.1 wt%, 0.2 wt%). The rheology and filtration characteristics were evaluated at the various concentration for two gemini surfactants. The shale inhibition characteristics were determined by capillary suction time test and linear swelling experiments. XRD analysis was performed to study the d-spacing of clay and the intercalation behavior of clay for both gemini surfactants. The stability of prepared drilling fluids with gemini surfactants was assessed by particle size distribution experiments. The wettability alteration of clay surface with gemini surfactants was determined by contact angle measurements. The experimental results showed the significant improvement in the shale inhibition characteristics of shale by reducing the linear shale swelling rate to 97.7% and 101% for the gemini surfactants with chloride counter ion (BPC) and gemini surfactants with bromide counter ion (BPB) respectively, at 0.2% concentration in the drilling fluid. The capillary suction time was significantly reduced to 312 s and 636 s for BPC and BPB, respectively, at 0.2% concentration. XRD analysis of clay exhibited that d-spacing increased after treating with gemini surfactants that indicate the intercalation of clay particles. All the experimental results showed that gemini surfactants having biphenyl as a spacer could be the possible additives of drilling fluid for the inhibition of shale.

Experimental Research of Shale Pellet Swelling in Nano-Based Drilling Muds

The drilling of clay-rich formations, such as shale, is an extremely demanding technical and technological process. Shale consists of mixed clay minerals in different ratios and in contact with water from drilling mud. It tends to swell and cause different wellbore instability problems. Usually, the petroleum industry uses various types of salt and/or polymers as shale hydration inhibitors. The aim of this research was to determine whether nanoparticles can be used as shale swelling inhibitors because due to their small size they can enter the shale nanopores, plug them and stop further penetration of mud filtrate into the shale formation. Swelling of bentonite-calcium carbonate pellets after 2 and 24 h in water and drilling mud (water, bentonite, PAC and NaOH) without nanoparticles and with addition of TiO2 (0.5, 1 and 1.5 wt%) and SiO2 (0.5, 1 and 1.5 wt%) nanoparticles was measured using a linear swell meter. Additionally, granulometric analyses of bentonite as well as the zeta potential of tested muds containing nanoparticles were performed. Based on the laboratory research, it can generally be concluded that the addition of SiO2 and TiO2 nanoparticles in water and base drilling mud reduces the swelling of pellets up to 40.06%.