Jitendra Sangwai

Drilling operations in oil and gas industry are associated with issues such as pipe sticking, poor wellbore cleaning and high fluid loss. Mitigation of such problems in water-based drilling mud (WBM) necessitates the application of nanotechnology in improving their filtration and rheological characteristics. In the present work, an attempt has been made to analyze the effect of nanofluid prepared using copper oxide (CuO) nanoparticles (NPs) dispersed in chia seed solution on WBM characteristics. Therefore, three samples of chia seed based nanofluids are synthesized using two-step method by varying the concentration of CuO nanoparticle from 0.2 wt% to 0.6 wt%. The resulting nanofluids are then mixed with WBM to prepare Nanofluid enhanced Water based Drilling Mud (NFWBM). The synthesized nanofluids are then characterized for their stability and thermal decomposition respectively using Scanning Electron Microscope (SEM) and Thermo-Gravimetric Analyzer (TGA). The NFWBMs are then analyzed for rheological and filtrate-loss properties at different temperatures of 30 °C, 50 °C, 70 °C and 90 °C. The hot roll aging process is carried out at 90 °C for 16 h maintaining the pressure at 0.1 MPa. The analysis projected a significant enhancement in the thermal stability of the WBM, with a reduction in viscosity of about 61.7% at 90 °C, which is critically observed to recover back to a significant extent of about 14% for chia based 0.4 wt% CuO nanofluid enhanced WBM and 19% for chia based 0.6 wt% CuO nanofluid enhanced WBM. Such improvement is observed in the rheological properties post hot rolling too. Further, the API fluid loss is observed to reduce from 7.2 ml to 6.8 ml, 6 ml, and 4.8 ml, respectively, before hot rolling, while the same reduced from 12.4 ml 11.4 ml, 10.2 ml, and 9.4 ml, respectively, for chia based 0.2 wt%, 0.4 wt%, and 0.6 wt% of CuO nanofluid enhanced water based drilling muds (NFWBMs). The present study aids in the development of novel and green additives for water-based muds to enhance their properties.

The Krishna Godavari offshore basin to the east of India is a proven reserve, rich in natural gas hydrate. The impact of sediment characteristics on the hydrate formation has already been well established in open literature. In the present study, we have attempted to investigate the mineralogy of sediments collected from KG basin by elemental analysis (energy dispersive spectroscopy) and x-ray diffraction. Various physicochemical characteristics of the clayey sediments such as TDS, salinity, pH, conductivity and resistivity were analysed at various concentrations and compared together. Also, this paper highlights the rheological behavior of the sediment samples with concentrations of 20, 35 and 50 wt% at different experimental temperatures (278.15 K, 283.15 K and 288.15 K). Viscosity measurements were performed for a wide range of shear rates for all concentrations and comparative studies have been conducted on their exhibited behavior. The viscosity of sediment sample were found to be varying from 76.3 to 0.003 Pa s depending on the sediment concentration, temperature and shear rate. In addition, viscoelastic measurements were carried out at various angular frequencies for all the sediment samples. The work aims to characterise the sediments of KG basin and analyse the rheological behavior of sediment solution which has not yet been reported in open literature. This will provide vital information for possible methane recovery from KG basin hydrate reservoir by manipulating the host sediment behavior.

Drilling fluid is one of the most important components of drilling operation in oil and gas, mining and geothermal industries. Nanotechnology can be used to develop drilling fluid additives that can improve the drilling fluid properties. In this work, the feasibility of using two types of nanoparticle additives in water-based drilling fluid has been investigated. Clay/SiO2 nanocomposite was synthesized (by effective hydrothermal method) and successfully characterised. A series of experiments are performed to evaluate the effect of SiO2 and clay nanoparticles on the rheological and filtration properties of water-base drilling fluids. The experiments are conducted at different concentrations of Clay/SiO2 and SiO2 nanoparticles, and also at a range of temperatures. The results showed that the addition of clay and SiO2 nanoparticles improved the rheological and fluid loss properties. It was also noticed that the nanoparticles provide thermal stability to the drilling fluid. The experimental results suggest that the Clay/SiO2 nanoparticles have a more significant impact on the rheological and fluid loss properties of the drilling fluid comparing to SiO2 nanoparticles, particularly at higher temperatures.

Carbon dioxide hydrates are solid crystalline compounds made of water and carbon dioxide gas. Rheological characterization of carbon dioxide (CO2) hydrates is vital for advancing, optimising, and developing CO2 hydrate-based technologies. In this work, the rheology of the CO2 hydrate slurry has been investigated with and without surfactant, sodium dodecyl sulfate (SDS), using a modified Couette geometry at a constant temperature of 274.55 K and varying pressures (3.5, 5, and 6.5 MPa). It was observed that at higher pressures, dissolved CO2 had been actively engaged in nucleation and growth, unlike free gas at lower pressures. Steady-state viscosities and flow curves vary proportionately with driving force, exhibiting shear thinning behaviour in good agreement with the Cross-model criterion. With the addition of SDS, both the peak and steady-state viscosities experience a drop for all the experimental pressures. Moreover, the flow curves and yield stress of hydrate slurries reduce with surfactant concentration, exhibiting pseudoplastic behaviour. Viscoelastic properties manifest solid behaviour for hydrate slurries formed at a higher pressure of 5 and 6.5 MPa whereas liquid behaviour dominates at lower pressure of 3.5 MPa. Eventually, the presence of SDS has been observed to delay the CO2 hydrate dissociation (3.54 ± 0.4 K/h for 2.5 h), signifying enhanced stability owing to surfactant blanketing/encircling the CO2 hydrate crystals. Thus, SDS facilitates CO2 hydrate flow under higher and lower pressures, administering an anti-agglomerating effect. This encourages its use in industrial applications like secondary refrigeration, cold storage, gas separation, and for improved hydrate slurry flowability in offshore pipelines.

Nanofluids show potential use in applications related to upstream oil and gas industry to improve the performance of several processes such as exploration, drilling and completion, production and enhanced oil recovery operations. However, their applications to water-based drilling mud (WBM) needs attention to address efficient drilling in an High Pressure and High Temperature (HPHT) environment. In the present work, nanofluid-enhanced WBM (NWBM) are prepared using the nanofluids of CuO and ZnO (size [U+02C2]50. nm) in a xanthan gum aqueous solution as a base fluid, and used as an additive in WBM. The nanofluids are prepared for nanoparticle concentrations of 0.1, 0.3 and 0.5. wt% in base. The prepared nanofluids are added as an additive of 1% (by volume) to WBM. The enhancement in thermal and electrical properties of NWBH is studied. It is observed that NWBM show improved thermal and electrical properties by about 35% compared to WBM. An increased concentration of nanoparticles further enhances electrical and thermal properties of drilling fluids. The NWBM based on CuO nanofluid are observed to show improved thermal properties, and are more resistant to HPHT condition than ZnO-based NWBM. High pressure rheological studies are conducted on NWBM to understand the effect of nanofluids on the rheological properties at varying temperatures (25, 70, 90 and 110. °C) and pressures (0.1. MPa and 10. MPa). The effect of pressure on the rheology of NWBM is more significant at higher temperatures, and indicates better rheological stability in case of NWBM. The most significant role that the nanofluids play is in stabilizing the viscosity at higher temperatures. The experimental data on flow curves obtained for various NWBM are fitted to the classical drilling fluid rheological models (Power Law model, Bingham Plastic model and Herschel-Bulkley model). The Herschel Bulkley model is observed to be the best fit-model for rheological behavior of NWBM and can be applied for efficient NWBM design. © 2014 Elsevier B.V.

Information on the viscosity of Pickering emulsion is required for their successful application in upstream oil and gas industry to understand their stability at extreme environment. In this work, anovel formulation of oil-in-water (o/w) Pickering emulsion stabilized using nanoparticle-surfactant-polymer (polyacrylamide) system as formulated in our earlier work (Sharma et al., Journal of Industrial and Engineering Chemistry, 2014) is investigated for rheological stability at high pressure and high temperature (HPHT) conditions using a controlled-strain rheometer. The nanoparticle (SiO2and clay) concentration is varied from 1.0 to 5.0 wt%. The results are compared with the rheological behavior of simple o/w emulsion stabilized by surfactant-polymer system. Both the emulsions exhibit non-Newtonian shear thinning behavior. A positive shift in this behavior is observed for surfactant-polymer stabilized emulsion at high pressure conditions. Yield stress is observed to increase with pressure for surfactant-polymer emulsion. In addition, increase in temperature has an adverse effect on the viscosity of emulsion stabilized by surfactant-polymer system. In case of nanoparticle-surfactant-polymer stabilized o/w emulsion system, the viscosity and yield stress are predominantly constant for varying pressure and temperature conditions. The viscosity data for both o/w emulsion systems are fitted by the Herschel-Bulkley model and found to be satisfactory. In general, the study indicates that the Pickering emulsion stabilized by nanoparticle-surfactant-polymer system shows improved and stable rheological properties as compared to conventional emulsion stabilized by surfactant-polymer system indicating their successful application for HPHT environment in upstream oil and gas industry.

Polymers have become an integral part of our daily lives with a wide range of applications. Oftentimes, the nature of application demands modifications of properties of polymer composites. Literature survey reveals that asphaltenes (high molecular weight and polar fractions of the crude oil) have been introduced in recent years as a filler to modify the properties of asphaltene-polymer composites. Asphaltenes are often considered as a waste product of petroleum industry but can have implications in strengthening of the polymer composites owing to improved filler-matrix interaction and formation of filler network via reorganization of the particles. In addition, certain polymer blends can improve the flow performance of the crude oil containing asphaltene and/or wax by modifying the rheological properties. This chapter discusses in detail the development in the field of asphaltene-polymer composites and flowability improvement of heavy crude oil using different polymer blends.

Emulsions have a wide range of applications, and with the advancement in the use of nanoparticles to form stable Pickering emulsions, it is important to understand their rheological properties to infer their stability under high-pressure and high-temperature (HPHT) compared to the emulsion formed using conventional surfactants. In oil and gas production strategies, oil often forms an emulsion with brine either within reservoirs or at surface facilities in the presence of natural or artificial surfactants. Nanoparticles are also being explored to increase oil recovery from matured reservoirs. In various instances, stable emulsions are either formed in-situ (within the reservoir) or at surface facilities or injected into the reservoir to mobilize the trapped oil. It is also essential to understand their rheology for efficient oilfield application. This study investigates the impact of surface-modified silica nanoparticles (Ludox CL), NaCl salt, and surfactant on the stability of oil-in-water Pickering and surfactant-stabilized emulsions under high-pressure (0.1–10) MPa and high-temperature (303–363) K conditions. The viscosity of emulsion samples was measured at varying shear rates (0.1–1000) s−1. The viscoelastic behavior (G′, G″, η*, and δ) of the Pickering emulsion and surfactant-stabilized emulsion were also measured. The stability of the emulsions was measured in terms of changes in emulsion viscosity and droplet diameter. Both emulsions showed non-Newtonian shear thinning behavior and an increase in droplet diameter under HPHT conditions. However, the surfactant-stabilized emulsion exhibits a greater degree of change in emulsion viscosity and droplet diameter than the Pickering emulsion. It indicates that the Pickering emulsion showed better stability than the surfactant-stabilized emulsion under HPHT conditions. Hence, Pickering emulsions are an incredibly promising tool that might be employed in HPHT applications, especially for enhanced oil recovery applications, due to their better rheological stability.

Exploration of shale gas has indeed changed the dynamics of the petroleum industry. Efficient drilling in shale bearing zones largely depends on the nature of drilling fluid that are used. Non-damaging drilling fluid (NDDF) has emerged as an important class of drilling fluids over the last decade due to its superior inhibitive nature that yields better wellbore conditioning, especially in formations where the shale content is very high. However, the thermal stability of this biopolymer-based drilling fluid has posed limitations in its application in moderate to high-temperature wells. This research presents comprehensive rheological, fluid-loss and computational fluid dynamics (CFD) analysis to study and quantify the effects of zinc oxide nanoparticle (ZnO NP) on the NDDF. It was found that ZnO NP enhances thermal stability by yielding a viscosity over 300% than that of the base NDDF at 80 °C. These NPs also induces viscoelastic solid property that nurtures superior gel forming and thixotropic ability. Furthermore, more than 80% the viscous structure is regained within a timeframe of 180 s with the addition of 0.8 and 1 wt% ZnO NP as compared to 44% for the base NDDF. With the addition of 1 wt% ZnO NP the operating temperature of NDDF reaches up to 100 °C. Besides, fluid-loss of NDDF is reduced by 49% with doping of 1 wt% ZnO NP in NDDF. CFD simulations show excellent cutting carrying capacity of ZnO NP NDDFs with 1 wt% concentration showing a reduction in cutting retention by 29.13% at high temperatures (80 °C). Furthermore, the velocity profile showed that skewness in case of ZnO NP NDDF is reduced, indicating a better sweep of cuttings in the annular region. Despite exhibiting viscoelastic properties, the pressure drop of ZnO NP NDDFs along a complex wellbore geometry was within an acceptable range, ensuring flowability.

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.