Clay Swelling Inhibitor Research Articles

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%.

Experimental and COSMO-RS Simulation Studies on the Effects of Polyatomic Anions on Clay Swelling.

Ionic liquids (ILs) can play a vital role in clay swelling inhibition during hydraulic fracturing. Previous studies highlighted the effect of side-chain length attached to the cationic core and different anions possessing almost the same chemical properties on inhibition performance. However, polyatomic anions have the potential to superiorly inhibit swelling compared to monoatomic anions. In this study, three ILs, namely, 1-butyl-3-methylimidazolium chloride (BMIMCl), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), were utilized to assess the effects of polyatomic anions on clay swelling inhibition. These performances were compared with the performances of a conventional inhibitor, potassium chloride (KCl). X-ray diffraction (XRD) testing was applied to check the mineral components present in the bentonite clay sample studied in this research. Clay swelling inhibition performance and rheological properties of these ILs were evaluated by the bentonite plate soaking test, linear swelling test, and rheological test. The swelling inhibition mechanisms were investigated through ζ-potential measurement, Fourier transform infrared (FT-IR) spectroscopy, and contact angle measurement. Moreover, COSMO-RS computer simulation was conducted to explain the inhibition mechanisms theoretically. The results demonstrated that BMIMPF6 showed superior inhibition performance and reduced the swelling by 21.55%, while only 9.26% reduction was attained by potassium chloride (KCl). The adsorption ability on the bentonite surface through electrostatic attraction, higher activity coefficient, and less electronegativity of PF6– anion played a vital role in attaining such superior inhibition performance by BMIMPF6.

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.

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.

Molecular simulation of polyether amines intercalation into Na-montmorillonite interlayer as clay-swelling inhibitors

Polyether amines (PEA) have been widely used in water-based drilling fluids (WBDFs) to prevent the clay swelling and maintain the wellbore stability during the drilling process due to its excellent inhibition performance and low toxicity towards the environment. Understanding the intercalation behavior of PEA within clay interlayer is of great significance to disclose the inhibition mechanism and design high-performance drilling fluid additives. In this work, molecular dynamic (MD) simulations are applied to investigate the arrangement and dynamic properties of neutral PEA (N-PEA) and protonated PEA (P-PEA) within Na-montmorillonite (MMT) interlayer in the presence of one, two and three layer water content. We found that the N-PEA molecules tend to interact with clay surface with the –NH2 groups and a stronger interaction between –NH3+ groups and clay surface is observed when 33% Na+ is replaced by P-PEA molecules. While for the scenario with 66% Na+ is substituted by P-PEA molecules, the –NH3+ groups prefer to distribute in the middle of the pore hydrating with water molecules. The N-PEA molecules are likely to form a crown-like structure wrapping Na+ inside which is detrimental for the water invasion into clay layer. Based on the analysis of Na+ distribution in MMT layer, it is observed that the introduction of P-PEA molecules replace the Na+ in the middle of the pore first and followed by the surface Na+. Both of the N-PEA and P-PEA molecules are capable of forming hydrogen bonding (H-bonding) with MMT surface reducing the propensity of MMT to attract water. Furthermore, the minimum H-bonding number between MMT and P-PEA molecules is observed when 66% Na+ is exchanged due to strong water-PEA interaction. In addition, the inhibition mechanisms of neutral PEA molecules by forming PEA-Na+ complexes to cut off the connection between Na+ and water molecules is similar for different water contents. Our study provides important insights into the structural properties of PEA molecules within MMT interlayer and clay inhibition mechanism of PEA.

Imidazolium-Based Ionic Liquids as Clay Swelling Inhibitors: Mechanism, Performance Evaluation, and Effect of Different Anions.

Clay swelling is one of the challenges faced by the oil industry. Water-based drilling fluids (WBDF) are commonly used in drilling operations. The selection of WBDF depends on its performance to improve rheology, hydration properties, and fluid loss control. However, WBDF may result in clay swelling in shale formations during drilling. In this work, the impact of imidazolium-based ionic liquids on the clay swelling was investigated. The studied ionic liquids have a common cation group, 1-allyl-3-methyllimidozium, but differ in anions (bromide, iodide, chloride, and dicyanamide). The inhibition behavior of ionic liquids was assessed by linear swell test, inhibition test, capillary suction test, rheology, filtration, contact angle measurement, scanning electron microscopy, and X-ray diffraction (XRD). It was observed that the ionic liquids with different anions reduced the clay swelling. Ionic liquids having a dicyanamide anion showed slightly better swelling inhibition performance compared to other inhibitors. Scanning electron microscopy images showed the water tendency to damage the clay structure, displaying asymmetrical cavities and sharp edges. Nevertheless, the addition of an ionic liquid to sodium bentonite (clay) exhibited fewer cavities and a smooth and dense surface. XRD results showed the increase in d-spacing, demonstrating the intercalation of ionic liquids in interlayers of clay. The results showed that the clay swelling does not strongly depend on the type of anion in imidazolium-based ILs. However, the type of anion in imidazolium-based ILs influences the rheological properties. The performance of ionic liquids was compared with that of the commonly used clay inhibitor (sodium silicate) in the oil and gas industry. ILs showed improved performance compared to sodium silicate. The studied ionic liquids can be an attractive alternative for commercial clay inhibitors as their impact on the other properties of the drilling fluids was less compared to commercial inhibitors.

Application of a Novel and Sustainable Silicate Solution as an Alternative to Sodium Silicate for Clay Swelling Inhibition.

Shale swelling during drilling operations causes many problems mainly related to wellbore instability. The oil-based muds (OBMs) are very effective in controlling the swelling potential of clay-rich shale formation, but their environmental concerns and the economic aspects curtail their usage. In the application of water-based mud (WBM), it is mixed with various swelling inhibitors such as inorganic salts (KCl and NaCl), sodium silicate, polymers, and amines of various types. The above-mentioned materials are however afflicted by some limitations in terms of their toxicity, their effect on drilling mud rheology, and their limited tolerance toward temperature and oil contamination. In this study, we investigated a novel hybrid aqueous alkali alumino silicate (AAAS) as a shale swelling inhibitor in WBM. The AAAS is a mixture of sodium, aluminum, and silicon oxides. Experimental investigations were carried out using a linear swell meter, hot rolling and capillary suction timer, ζ-potential test, filtration test, and rheology test. The application of hybrid silicate as a swelling inhibitor was studied in two phases. In the first phase, only silicate solutions were prepared in deionized water at various ratios (1, 2, and 5%) and tested on sodium bentonite and shale samples containing high contents of kaolinite clay. Further testing on commonly used inhibitors such as KCl and sodium silicate solutions was conducted for comparative purposes. In the second phase, different drilling mud formulations consisting of various percentages of AAAS were mixed and tested on original shale samples. It was observed that the novel silicate-based mix proved to be a strong shale swelling inhibitor. Its inhibition performance was better as compared to the sodium silicate solution and KCl solution. It not only inhibits shale swelling but also acts as a shale stabilizer due to its high adsorption on the shale surface, which prevents the shale/water reactivity, makes the shale formation stronger, and prevents caving.

Influence of (3–Aminopropyl) triethoxysilane on entrapped polypropylene at nanosilica composite for shale swelling and hydration inhibition

The unforgiving shale formations require special shale inhibitors to mitigate wellbore instability problems. (3–Aminopropyl) triethoxysilane polypropylene-nanosilica composite (PNSC + NH2) was evaluated in water-based drilling muds (WBDMs) as a clay swelling and hydration inhibitor. The size distribution, functional groups, morphology, and thermal stability of the PNSC + NH2 were studied. Rheological and filtrate volume tests were carried out to determine the influence of the PNSC + NH2 on WBDMs. The clay swelling inhibition performance of the PNSC + NH2 mud system was examined and compared with that of potassium chloride (KCl) and KCl + partially hydrolyzed polyacrylamide (KCl + HPAM) through clay swelling inhibition test, extended clay swelling inhibition test (inhibition longevity test), and BET analysis test. Four shale specimens were prepared with compactor cell for the measurement of clay swelling using the Linear Swell Meter. Drilling muds were examined on 16 mm thick-compacted shale pellets using the highest concentration of smectite. A shale rolling recovery test was conducted to determine the shale hydration-retardation. Results showed that the PNSC + NH2 particle has good dispersibility, with a size distribution predominantly distributed between 80 and 390 nm. The inclusion of 1.5w/v% PNSC + NH2 concentration enhanced the plastic viscosity and yield point of WBDM from 11 to 15 mPa s and 9–14 Pa, respectively. Also, it reduced the API filtrate volume of the WBDM from 10.2 to 7.8 ml. The clay swelling inhibition performance of the WBDM for 36 h showed 62% swelling and was reduced to 42% by KCl, 33% by KCl + HPAM, and 28% by PNSC + NH2. When the inhibition test was extended to 60 h, the swelling increased to 44% for KCl, 40% for KCl + HPAM, and 29% for PNSC + NH2 mud systems. These results revealed that the PNSC + NH2 has the best inhibition performance due to its ability to provide the greatest long-lasting inhibiting effect on the clay surface. When the shale cuttings with the various mud systems were subjected to 150 °C for 16 h in an ageing steel cell, the shale recovery rate at 1.5w/v% concentration confirmed that the PNSC + NH2 exhibited 75.3 wt%, while that of the base mud, KCl, and KCl + HPAM systems demonstrated 33.6, 58.4, and 63.1 wt%, respectively. The BET surface area of the shale reduced significantly by 52.3% with 1.5w/v% PNSC + NH2 from 14.72 to 7.02 m2/g. The wettability determination of the shale surface showed a contact angle of 36.8° which improved to 68.4° by 81.0% with 2.0w/v% PNSC + NH2 concentration. The application of PNSC + NH2 for clay swelling and hydration inhibition proved to be promising and could be effective for drilling shales.

Experimental evaluation of thiamine as a new clay swelling inhibitor

This study aims at evaluating the performance of thiamine as a new eco-friendly shale inhibitor in water-based drilling fluids (WBDFs). The evaluation experiments include sedimentation, bentonite inhibition, filtration, zeta potential, thermal gravimetric analysis, scanning electron microscopy, X-ray diffraction, shale cuttings recovery, linear swelling and Fourier transform infrared spectroscopy (FTIR). The performance of thiamine was compared to potassium chloride. In contrast to deionized water, the aqueous solution of thiamine exhibited greater power to inhibit montmorillonite (Mt) dispersion, much more Mt loading capacity (280 g/L) and fluid loss, lower Mt mass loss, larger aggregated Mt particles, lower interlayer space of the Mt particles, less shale cuttings disintegration and lower linear swelling. Adsorption of thiamine on Mt led to a significant shift in the value of zeta potential (from −17.1 to +8.54 mV). Thiamine demonstrated superior inhibitive performance than potassium chloride. FTIR analysis confirmed that thiamine is adsorbed on Mt particles. The compatibility test revealed the compatibility of thiamine with conventional WBDF additives. It was concluded that the main probable inhibition mechanisms of thiamine are the cation exchange and Mt surface coating. In view of its prominent inhibition capacity and great environmental acceptability, thiamine is a promising inhibitor for drilling in water-sensitive formations.

Clay Swelling Inhibition Using Novel Cationic Gemini Surfactants with Different Spacers

AbstractHydration of shale formation by water‐based drilling fluids leads to several problems, such as the collapse of boreholes, tight holes, and stuck pipe, which may impede further drilling and time loss in rectifying the problems, leading to heavy economic losses. This study reports the development of new gemini cationic surfactants as shale‐swelling inhibitors. These gemini surfactants are structurally similar but differ in terms of the spacer group. Saturated butyl group (GS1) and unsaturated 2‐butenyl (GS2) and 2‐butynyl (GS3) were introduced as spacer groups of gemini surfactants. To assess the performance of new gemini cationic surfactants, two reliable clay sources were considered. The first clay is from an unconventional formation and the second clay is sodium bentonite. The inhibition characteristics of gemini surfactants were evaluated using dynamic swelling, hot rolling, rheology, and filtration experiments. Different formulations based on commercially available solutions for shale‐swelling inhibitors were applied and compared with cationic shale inhibitors. It was observed that the new gemini cationic surfactants with different spacers (saturated and unsaturated) reduced the shale swelling by different percentages. The GS2 surfactant, containing an unsaturated double bond proved to be a good swelling inhibitor as compared to GS1 and GS3. It also showed acceptable performance compared with the common shale inhibitor (KCl) used in the industry. The addition of surfactant has less impact on the rheological properties as compared to KCl. The filtration properties of the base mud were unchanged when surfactants were used. However, the commercial inhibitor, KCl, significantly increased the filtration volume that is associated with the disintegration of the clay. In summary, unlike commercial inhibitors, the synthesized surfactants reduced the clay swelling without affecting the other properties of the drilling fluids.

Quaternary ammonium gemini surfactants having different spacer length as clay swelling inhibitors: Mechanism and performance evaluation

Abstract The swelling of shale formation upon exposure to water-based drilling fluids leads to several problems. Common shale (clay) inhibitors used in the industry have several shortcomings which adversely affect the drilling mud properties. This study involves the development, application, and mechanism of new quaternary ammonium gemini cationic surfactants as clay swelling inhibitors. These gemini surfactants are structurally similar but different in terms of the spacer lengths. The inhibition characteristics of gemini surfactants were evaluated using a linear swell tester, capillary suction timer, scanning electron microscope (SEM), rheology, filtration, wettability, and zeta potential analysis. It was observed that the new gemini cationic surfactants with various lengths of spacers reduced the clay swelling. The GS12 surfactant, containing flexible large spacer C12 proved to be a beneficial swelling inhibitor as compared to GS8 and GS10 due to increased hydrophobicity. It also showed acceptable performance compared to the common shale inhibitor used in the industry. SEM images revealed that water caused significant damage to clay structures showing irregular and sharp edges. However, the surfactant-treated clay showed a fine, dense, and smooth surface. An inhibition mechanism using synthesized surfactants was also proposed. Experimental tests showed the synthesized surfactants adsorb and intercalate between layers of clay through hydrogen bonding and attractive electrostatic forces. The orientation of lipophilic tails inhibits the water adsorption in the clay which results in reduced clay swelling. The synthesized surfactants reduced the clay swelling without affecting the other mud properties such as rheology, stability, and filtration properties.

Low Molecular Weight Branched Polyamine as a Clay Swelling Inhibitor and Its Inhibition Mechanism: Experiment and Density Functional Theory Simulation

The inhibition of clay surface hydration is a major hindrance for the use of water-based drilling fluids (WBDFs) in shale formations. In this work, a low molecular weight branched polyamine (BEN-5N...

Synthesis and mechanism research of a new low molecular weight shale inhibitor on swelling of sodium montmorillonite

AbstractShale gas as green and clean energy is attracting more interest. However, shale hydration and swelling have become the major challenges using water‐based drilling fluids, replacing oil‐based drilling fluids, for developing shale gas. In this work, a low molecular weight branched polyamine (NETS) as clay swelling inhibitor was synthesized. The NETS performed excellent inhibition property by linear expansion experiments and cuttings hot‐rolling recovery. The inhibition mechanism of NETS was investigated using X‐ray diffraction, fourier transform infrared spectroscopy, cation exchange capacity, X‐ray photoelectron spectroscopy, scanning electron microscopy, and zeta potential. The results show that the NETS can adsorb on Na‐Mt, decrease the basal spacing of wet Na‐Mt from 1.91 to 1.43 nm, and replace majority sodium ions from interlayer of Na‐Mt. However, replaceability of sodium ions and inhibition of water molecules of ethylenediamine are worse than NETS. These indicate that the primary amines of NETS had strong interaction with Na‐Mt, tensed clay layers and decrease the basal spacing. The combination of long hydrophobic chain and primary amines makes NETS to adsorb on surface of Na‐Mt, intercalate into interlayer of Na‐Mt with tilted monolayer arrangement, and replace sodium ions. The more the number of primary amine groups, the better the inhibition performance. Therefore, NETS has a great potential to be an outstanding shale inhibitor of water‐based drilling fluids in the future.

Stabilization of the swelling soil for earth construction

This study is concerned with the method of cast earth as part of an investigation series on earth construction. The effect of two clay swelling inhibitors; polyethylene glycol [PEG] and of carboxymethyl cellulose [CMC] on the swelling of a clay-bearing soil are studied to enable the stabilization of the soil with CEM I 42.5 N. The soil composed of 14% clay, quartz, and calcite, is stabilized with 10% cement. 3% polycarboxylate superplasticizer is added relative to the mass of the cement, to gain the soil pourable properties. The results show that the PEG and CMC clay-swelling inhibitors reduce the expansion of the soil by ~30 and ~40% and lead to a maximum increase of 24 and 46% in the 90-day compressive strength respectively. The interactions between clay, cement, and swelling inhibitors are discussed. The findings allow advantageous applications for producing building units for construction purposes in desert areas.

Interaction between Polymer-Based Drilling Fluids Containing Ordinary Salts and Clay Rocks

The study of the interaction processes between polymer-based drilling fluids and clay rocks is essential. Careful selection of drilling fluid composition will allow you to avoid such complications during drilling as the bridge over, clogging of the bottom-hole zone with cuttings, reduction of the mechanical drilling speed, differential wall sticking, a fluid wash of the wellbore walls and core plugs, and drilling fluid losses. Various salts of alkali and alkaline earth metals are often used as clay swelling inhibitors, which can cause changes in the rheological properties of the drilling fluid on their addition at high concentrations. The paper presents the experimental results of determining the swelling value of the clay mineral illite in drilling fluids prepared on the basis of cationic (K-6729) and anionic (EZ-MUDDP) polymers with the addition of inorganic salts – potassium chloride, sodium chloride and sodium silicate. The rheology of the tested samples deteriorates when salts are added to polymer solutions. This fact is explained by the hydration of salts and water molecules binding to the hydration shells of electrolyte ions, as well as the destruction of hydrogen bonds in water's structure with an increase in its molecular mobility. The paper demonstrates that in a sodium silicate solution, the hydration and swelling of illite are significantly inhibited. Thus, the change in the linear dimensions of pressed clay powder tablets with different permeabilities in distilled water, potassium, and sodium chloride solutions amounted to 30%, while in sodium silicate solution it did not exceed 6.3%. However, compared to potassium and sodium chlorides, when sodium silicate as a clay inhibitor, then the rheological characteristics of the drilling fluid decrease less significantly.

Influencia de las concentraciones de goma xantano, hidroxipropil almidón y cloruro de potasio sobre las propiedades de flujo de las formulaciones de fluidos de perforación

Drilling operation of oil wells involves high costs and risks. With recent discoveries of deeper reservoirs and difficult to access, there was an increase in the number of horizontal wells drilled and far-reaching, and, thereat, new challenges with operational problems. Fluids, or muds, drilling are essential to the well drilling process, confirming the need to study and find physical, rheological, and filtration properties, appropriate to the complexities in each section and the drilling stage. Optimized formulation is the one that comprises a safe operation, mitigation of operational problems, environmental protection, low cost, and high productivity. Thus, this paper offers the study of the rheological properties, and determination of filtrate volume, of the aqueous base fluid formulations, developed with polymeric additives. A high performance formulation, presenting technical-economical feasibility for drilling operations, was achieved using 0.43% m/v of viscosifier (xanthan gun), 0.57% m/v of filtrate controller (hydroxypropyl starch) and 4.57% m/v of clay swelling inhibitor (KCl)

A novel non-ionic surfactant extract derived from Chromolaena odarata as shale inhibitor in water based drilling mud

High performance clay swelling inhibitors play a vital role in improving inhibition characteristics of shales. The linkages between the inhibition's characteristics of the non-ionic surfactant extract from bio-based inhibitors are yet to be fully explored in the literature. This paper reports the use of a crude extract containing saponins from Chromolaena odorata (CO) leaf, which act as surfactants for inhibiting shale hydration. Determination of the inhibitive property of nonionic surfactant was made through measurements of surface-active properties, inhibition tests, filtration, rheological and strength test.The experimental findings on CO showed that it was highly compatible and very stable with conventional water-based drilling fluids (WBDFs), a highly effective shale inhibitor and a works through plugging and viscosity acting effect in the shale system.

INHIBITED SOLUTION RECIPE FOR ACTIVE CLAYS DRILLING

Background The relevance of the study is due to the need to improve the inhibitory ability of the drilling fluid in order to preserve the stability of the wellbore drilling clay rocks in the South Priobskoye field. Aims and Objectives: o study of the effectiveness of the addition of inhibitors of swelling of clays in various concentrations to the studied drilling fluid; o study of the tendency to oily formation of drilling fluids containing clay swelling inhibitors. Results The effect of various inhibitors of clay swelling on clay content, filtration rate and oily formation of drilling mud was analyzed. Laboratory studies have shown that the addition of various swelling inhibitors to the test drilling fluid has consistently improved the parameters of this solution, namely: clay intensity, water loss and resistance to the formation of glands. Lower readings of the filtration index and clay intensity ensure that the Inhibitor-2 reagent is introduced into the initial drilling mud. The optimal concentration of this reagent in the total solution volume is 5 %.

Primary evaluation of a natural surfactant for inhibiting clay swelling

Water-based drilling muds, a more environment-friendly candidate than oil-based drilling muds, are wildly used for drilling oil and gas wells. When water-based drilling mud is used for drilling formations with shale containing active clay constituents, it is challenging to preserve stability of the borehole due to clay swelling unless proper inhibition mechanisms are foreseen. In the current study, the feasibility of using Korean red Ginseng root extract was assessed as a clay swelling inhibitor. This root extract is rich in non-ionic surfactants such as Ginsenosides Rg3, Rg5, and RK1, and is referred to as “biosurfactant” throughout this manuscript. After preparation of mud systems containing problematic clay particles, the clay-swelling inhibition performance of the biosurfactant was systematically investigated through a series of tests, including mud formation, filtration, immersion, sedimentation assisted with optical microscopy, wettability by sessile drop technique, use of thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR), and shale cuttings recovery. The clay-swelling inhibition performance of the biosurfactant was then compared against two clay swelling inhibitors namely CTAB (Cetrimonium bromide, a known cationic surfactant) and potassium chloride. There are some properties associated with the mud systems prepared with biosurfactant solution which makes this product unique. These properties include: remarkable loading capacity of sodium montmorillonite (Mt) which in turn resulted in low rheological profile, poor fluid loss control, creation of stable Mt pellets, creation of larger size and aggregated Mt particles with less hydrophilicity, creation of fully unstable dispersed Mt particles that resulted in good sedimentation over time, less mass loss, and higher shale cuttings recovery, all compared to the baseline fluid made without the presence of biosurfactant. The results of this study indicate that the biosurfactant provides excellent clay swelling inhibition properties, comparable to known inhibitors. The biosurfactant's compatibility with other drilling mud components was also checked, and it was found that the fluid properties are independent of the biosurfactant. The wettability and FTIR analyses were also performed to investigate the mechanisms involved in clay swelling inhibition of the biosurfactant, which are believed to be as a result of coating the clay active surfaces with a hydrophobic layer, hence repelling the water phase. This hydrophobic layer is probably formed by interactions of the hydrophilic group of the Ginsenosides and the oxygen atoms available on the Mt surfaces, when the hydrophobic tail is oriented toward the aqueous phase.

Molecular Simulation Study of Montmorillonite in Contact with Water

Grand canonical Monte Carlo and molecular dynamics simulations were applied to understand the molecular mechanism of ion and water transport in montmorillonite clays as a function of relative humidity (RH). The variation of basal spacings of montmorillonite as a function of RH predicted based on the swelling free energy profiles was consistent with X-ray data. The hydration of the montmorillonite shows the following well-known order: Mg2+ > Ca2+ > Sr2+ > Li+ > Na+ > K+. The relative contribution of water on external surfaces only becomes significant close to the saturation pressure. However, this behavior for K-montmorillonite starts to occur well below the saturation pressure due to the clay-swelling inhibition by potassium ions. The diffusion of water and ions generally increases with RH in all samples. However, for samples with weakly hydrated ions, the water mobility in thin films adsorbed on external basal surfaces of clay can be higher than that in the water-saturated mesopores. For a given RH, mobi...