Vikas Mahto

Development of Non-damaging and Inhibitive Water Based Oil Well Drilling Fluids

The bridging agent plays very important role in the development of nondamaging water-based drilling fluid systems as it controls the water loss and the formation of filter cake thickness, which is desirable for the prevention of formation damage. These drilling fluids are inhibited with potassium or sodium chloride to increase the well bore stability during drilling operations. Keeping the previous in view, experimental studies have been carried out to study the new generation nondamaging and inhibitive drilling fluid system using xanthan gum, polyanionic cellulose, starch, calcium carbonate, and fly ash. It was observed that drilling fluids developed using fly ash as bridging agent have maintained good rheological properties and have better control on fluid loss and filter cake thickness than the calcium carbonate.

Study of the Effect of Xanthan Gum Based Graft Copolymer on Water Based Drilling Fluid

This research article consists of the synthesis of xanthan gum (XG)-g-polyacrylamide (PAA) copolymer and its effect in the development of water based drilling fluids. The graft copolymer was synthesized with varying concentration of XG to obtain shear stable and long chain graft copolymer. The obtained graft copolymer was characterized by Fourier transform infrared spectroscopy and Field emission scanning electron microscopy. The synthesized graft copolymer was then utilized as an additive for the development of water based drilling fluid system. The rheological properties of developed drilling fluids have increased significantly with the increase in graft copolymer concentration and these fluids have the capability to control fluid loss during filtration studies. The fluid loss volume was further reduced to 7 ml after the addition of bridging agent. The filtration and rheological properties of this system were compared with conventional water based drilling fluid system developed using partially hydrolyzed polyacrylamide polymer. It was observed that drilling fluid developed using graft copolymer has better rheological and filtration properties than the drilling fluid formulated using partially hydrolyzed polyacrylamide polymer.

Rheological investigations of water based drilling fluid system developed using synthesized nanocomposite

In the present study, polyacrylamide grafted xanthan gum/multiwalled carbon nanotubes (PA-g-XG/MWCNT) nanocomposite was synthesized by free radical polymerization technique using potassium persulfate as an initiator. The polyacrylamide was grafted on xanthan gum backbone in the presence of MWCNT. The synthesized nanocomposite was characterized by X-ray diffraction technique (XRD), and Fourier transform infrared spectroscopy analysis (FT-IR). The morphological characteristics of the nanocomposite were analyzed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analyses. Also, its temperature resistance property was observed with Thermogravimetric analysis (TGA). The effect of nanocomposite on the rheological properties of the developed drilling fluid system was analyzed with a strain controlled rheometer and Fann viscometer. Flow curves were drawn for the developed water based drilling fluid system at elevated temperatures. The experimental data were fitted to Bingham, power-law, and Herschel Bulkley flow models. It was observed that the Herschel Bulkley flow model predict the flow behavior of the developed system more accurately. Further, nanocomposite exhibited non-Newtonian shear thinning flow behavior in the developed drilling fluid system. Nanocomposite showed high temperature stability and had a significant effect on the rheological properties of the developed drilling fluid system as compared to conventionally used partially hydrolyzed polyacrylamide (PHPA) polymer.

Tragacanth gum: An effective oil well drilling fluid additive

The low penetration rate, excessive torque and drag, poor hole cleaning and formation damage are major impediments in drilling oil and gas wells. These have a major impact on drilling efficiency and well economics. Keeping these in mind, an attempt was made to design a water based drilling fluid system using Indian bentonite clays and tragacanth gum. The effect of tragacanth gum on rheological behavior of three different Indian bentonite water suspensions was studied and a drilling fluid system was developed. The filtrates of these drilling fluids were subjected to formation damage study on the field core using Ruska Liquid Permeameter. The laboratory investigation furnishes that tragacanth gum acts as a good viscosifier and fluid loss control agent. The drilling fluid filtrate also has less effect on formation damage.

Study of the Gelation and Rheological Behavior of Carboxymethyl Cellulose-Polyacrylamide Graft Copolymer Hydrogel

This research article deals with the synthesis of carboxymethyl cellulose-g-polyacrylamide copolymer and its suitability for the development of hydrogel system using cross-linker. The hydrogels were prepared using different concentrations of synthesized graft copolymer and chromium(III) acetate cross-linker. The gelation and rheological behaviors of this gel system were thoroughly studied. It was experimentally observed that the prepared hydrogels exhibit an acceptable gel strength and gelation time. The graft polymeric gel using 10,000 ppm copolymer and 2000 ppm chromium(III) acetate cross-linker could be deformed up to 7690% without tearing of the gel network in the range of 0.1–10,000% strain. These observations show the potential of the developed hydrogel system for its application as sealant during water shutoff jobs in oil reservoir. GRAPHICAL ABSTRACT

Rheological study of partially hydrolyzed polyacrylamide-hexamine-pyrocatechol gel system

BackgroundThe cross-linked polymer gels exhibit non-Newtonian rheological behavior which can be described well by the different types of rheological models. This study investigates the onset of gelation behavior of partially hydrolyzed polyacrylamide-hexamine-pyrocatechol polymer gel system which may be used to control excessive water production in the oil fields. Rheological measurements of this system have been performed at different time intervals and pH at 90°C. Attempts have been made to validate the onset of gelation behavior with Bingham plastic, Herschel-Bulkley, Mizrahi-Berk, and Robertson-Stiff model.ResultsIt was observed that the developed polymer gel system under the present study has better agreement with the Robertson-Stiff model.ConclusionsThe viscosity of cross-linked polymer gel solution increases with temperature with the passage of time. This increased viscosity leads to gel formation which in turn behaves as flow diverting agent or blocking agent for controlling excessive water production in the oil fields.

Synthesis, characterization and evaluation of polyacrylamide graft starch/clay nanocomposite hydrogel system for enhanced oil recovery

In this paper the suitability of a graft polymer nanocomposite hydrogel system for enhanced oil recovery was examined using polyacrylamide graft starch/clay nanocomposite (a laboratory synthesized product) and chromium (III) acetate (crosslinker). X-ray diffraction analysis, Fourier transform infrared spectrometry analysis, field-emission scanning electron microscopy and transmission electron microscopy were carried out to reveal the laboratory synthesized product as a nanocomposite. The effects of various parameters like salt concentration, pH, temperature, polymer concentration and crosslinker concentration on the properties of the developed gel system were systematically evaluated. The thermal stability of the nanocomposite gel and the conventional gel system were also determined by thermogravimetric analysis. The graft polymer nanocomposite gel system exhibited acceptable gel strength, gelation time and gel stability compared with the conventional gel system. The nanocomposite gels prepared using a low crosslinker concentration showed higher gel strength and required longer gelation time than the conventional gel which is more desirable properties for the effective placement of gel during enhanced oil recovery operations. In addition, sand pack flooding experiments show that the graft polymer nanocomposite gels had better plugging capacity than the conventional gel systems under reservoir conditions. Hence, this gel system may be suitable in the water shutoff treatments required for enhanced oil recovery from oilfields.

Preparation, Characterization and Coreflood Investigation of Polyacrylamide/Clay Nanocomposite Hydrogel System for Enhanced Oil Recovery

ABSTRACT The synthesis and characterization of polyacrylamide/clay nanocomposites for the development of hydrogel system used in enhanced oil recovery is described. The synthesized nanocomposite copolymer was crosslinked with Chromium (III) acetate to form the hydrogel which exhibited an acceptable gel strength, gelation time and gel stability. The nanocomposite gels prepared with low crosslinker concentration (2000 ppm chromium acetate) showed higher gel strength and required longer gelation time than the conventional polyacrylamide (PAAm) gel; these are desirable properties for the effective placement of gel during enhanced oil recovery operations. The effects of various parameters, such as polymer and crosslinker concentration, on the gelation time and gel strength were evaluated using the bottle testing method. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) revealed the formation of intercalated and exfoliated clay morphologies. The effects of the clay content on the thermal stability and gel strength of the gel network were also investigated by thermogravimetric analysis (TGA) and rheological measurements (oscillatory time sweep profiles), respectively. Also, in-situ gelation and core flooding experiments revealed that a significant permeability reduction of the sand pack cores could be achieved at reservoir conditions when they were treated with the developed nanocomposite gel formulation. Hence, this nanocomposite gel system with low crosslinker concentration (10,000 ppm of nanocomposite polymer concentration containing 2000 ppm of clay with 2000 ppm chromium acetate crosslinker) may be suitable in water shut-off treatments required for enhanced oil recovery from the oil fields.

Modeling of Partially Hydrolyzed Polyacrylamide-Hexamine-Hydroquinone Gel System Used for Profile Modification Jobs in the Oil Field

The cross-linked polymer gel systems are being used increasingly to redirect or modify reservoir fluid movement in the vicinity of injection wells for the purpose of permeability/profile modification job in the oil field due to their high temperature stability and capability to provide rigid gel having high mechanical strength. In this study, a partially hydrolyzed polyacrylamide-hexamine-hydroquinonegel is used for the development of polymer gel system. The experimental investigation demonstrates that the gelation time varies with polymer and crosslinker concentration and the temperature. The mathematical model is developed with the help of gelation kinetics of polymer gel and using Arrhenius equation, which relates the gelation time with polymer, crosslinker concentrations, and temperature. The developed model is solved with the help of multivariate regression method. It is observed in this study that the theoretical values of gelation time have good agreement with the experimental values.

Characterization of Indian Bentonite Clay Samples for Water-based Drilling Fluids

Abstract The rheological properties and filtration loss property of water-based drilling fluids greatly depends upon the quality and quantity of the bentonite clay, as well as the additives that are used in their formulations. To ascertain the quality of the bentonite clay, three raw Indian bentonite clays have been characterized using X-ray diffraction techniques and X-ray fluorescence techniques. The physicochemical properties, like swelling index, cation exchange capacities, and yield of clay, have also been carried out using standard API recommended procedures. The laboratory investigation reveals that these three bentonite clays are quite suitable for the development of water-based oil well drilling fluids.