Properties Of Water-based Drilling Fluids Research Articles

An Improvement in Thermal and Rheological Properties of Water-based Drilling Fluids Using Multiwall Carbon Nanotube (MWCNT)

Designing drilling fluids for drilling in deep gas reservoirs and geothermal wells is a major challenge. Cooling drilling fluids and preparing stable mud with high thermal conductivity are of great concern. Drilling nanofluids, i.e. a low fraction of carbon nanotube (CNT) well dispersed in mud, may enhance the mixture thermal conductivity compared to the base fluids. Thus, they are potentially useful for advanced designing high temperature and high pressure (HTHP) drilling fluids. In the present study, the impacts of CNT volume fraction, ball milling time, functionalization, temperature, and dispersion quality (by means of scanning electron microscopy, SEM) on the thermal and rheological properties of water-based mud are experimentally investigated. The thermal conductivities of the nano-based drilling fluid are measured with a transient hot wire method. The experimental results show that the thermal conductivity of the water-based drilling fluid is enhanced by 23.2% in the presence of 1 vol% functionalized CNT at room temperature; it increases by 31.8% by raising the mud temperature to 50 °C. Furthermore, significant improvements are seen in the rheological properties—such as yield point, filtration properties, and annular viscosity—of the CNTmodified drilling fluid compared to the base mud, which pushes forward their future development.

Effects of interactions between solids and surfactants on the tribological properties of water-based drilling fluids

In oil well drilling the rotating pipe bears against the side of the hole at numerous points, giving rise to two main friction manifestations, known as torque and drag. Torque refers to the pipe resistance to rotation and drag to hoisting and lowering. Excessive torque and drag can cause unacceptable loss of power making oil well operations less efficient, especially in high-angle and extended-reach wells. In this work, it had been studied the effects of a surfactant additive (SA) and its dissolution in diesel (SB), on the tribological and rheological properties of water-based fluids (WBFs) formulated with two weighting materials (hematite and calcium carbonate). The tribological properties were established by measuring the coefficient of friction (CF) in conjunction with optical surface profilometry used to evaluate the wear behavior. The viscosity was determined as a function of shear rate in the interval 0.1–1000 s −1. Additionally, light scattering techniques were performed to study the dispersion stability of solid particles (weighting materials) in the aqueous surfactant solutions, and to correlate the solid–surfactant interactions observed with the tribological and rheological properties of WBFs. Based on the results, it was established that the evaluated surfactant additive can reduce significantly the CF independently of the weighting materials used, and that SA formulation has a superior performance in CF reduction than SB. Concerning the rheological properties, it was observed a viscosity increase in the polymeric WBFs formulated with hematite and SA, indicating strong interactions in the polymer–surfactant–solid system. In all other formulations there was no effect on the rheological behavior.

Effects of Walnut Shells on the Rheological Properties of Water-Based Drilling Fluids

In this research, three different water-based drilling fluids were prepared according to American Petroleum Institute (API) standards, and effects of walnut shells on the rheological properties of the samples were studied. The walnut shells of 2-, 4-, and 6-mm samples and their equal weight mixtures of 2–4 mm and 4–6 mm were added to the drilling fluid samples in different concentrations. The aim of this study is to determine the optimum walnut shell size, concentration and polymer concentration to minimize the fluid loss during drilling operations. It was observed that polymer (XT) has the optimum effects on the water-based drilling fluid. The optimum concentration of polymer (XT) with the 6-mm walnut shell is determined as 0.4 g/350 ml.

04/00067 A study of wellbore stability in shales including poroelastic, chemical, and thermal effects: Chen, G. et al. Journal of Petroleum Science and Engineering, 2003, 38, (3–4), 167–176

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

Effect of Additives and Aging on the Rheological Properties of Water-Based Drilling Fluid

In order to achieve the optimum performance of any mud during drilling operations, the physical as well as the chemical properties of the mud must be carefully controlled by adding sufficient quantity of additives. Viscosity, gel-strengths (initial and 10 min), and fluid loss are of particular consideration while designing a drilling fluid. This article will mainly deal with studies on effect of additives and aging on behavior of the rheological properties of the bentonite clay of the Bhavnagar area of Gujrat.