An alternative method to enhance w/o emulsion stability using modified dimer acid and its application in oil based drilling fluids

Abstract

This study presents an alternative method to enhance the emulsion stability of oil based drilling fluids (OBMs). Modified dimer acid (MDA) was synthesized with a molecular structure having two hydrophilic heads and two hydrophobic tails. Theoretically, the adsorption of MDA on an oil-water interface makes it possible to increase hydrogen bonding between water droplets and form three dimensional networks which benefit emulsion stability. The influence of MDA on the stability of base emulsions was studied by visual observation. Then the stabilization mechanism of MDA was analyzed from the micro and macro points of view by morphology study using a cryo-scanning electron microscope (cryo-SEM) and rheological measurements including viscosity vs. shear rates, zero-shear viscosity (h 0 ), and creep and recovery tests. Experimental results showed that a substantial improvement in emulsion stability was visually observed when the MDA concentration was 2 g L À1. From cryo-SEM observation, a honeycomb structure was observed in the emulsion containing 2 g L À1 MDA, which can provide a physical barrier to restrain the movement of water droplets. In comparison with the rheological behaviors of the emulsion without MDA, a remarkably larger zero-shear viscosity, a solid-like behavior and a greater elasticity were observed when 2 g L À1 MDA was present. Finally, the application in OBMs shows that MDA can largely enhance electrical stability (ES) and reduce the filtration volume. The method proposed in the paper could be used to enhance the stability of w/o emulsions in a variety of fields.

Modified Nanopolystyrene as a Plugging Agent for Oil-Based Drilling Fluids Applied in Shale Formation

“…Performances of OBMs, such as rheological properties, emulsion stability, and FL at high temperatures and high pressures, play an essential role in carrying the debris and keeping the wellbore stability. , The high viscosity may interfere with the wellbore stability by inducing the suck and surge pressure, and reduce the drilling speed . If the emulsion stability of OBMs was broken, water from OBMs would interact with the rock to make shale hydration, leading to a wellbore slough . A high FL indicates more liquid from drilling fluids invading the formation, which is disadvantageous to keeping the wellbore stability .…”

“…57 If the emulsion stability of OBMs was broken, water from OBMs would interact with the rock to make shale hydration, leading to a wellbore slough. 56 A high FL indicates more liquid from drilling fluids invading the formation, which is disadvantageous to keeping the wellbore stability. 58 Therefore, keeping appropriate performances of OBMs is quite important.…”

Improving the Weak Gel Structure of an Oil-Based Drilling Fluid by Using a Polyamide Wax

“…Therefore, worldwide research has been conducted on rheology modifiers for OBDFs. Currently, rheology modifiers for OBDFs include oil-soluble polymers [ 16 , 17 ], modified fatty acids [ 18 ], and nanocomposites [ 19 , 20 ]. Ma et al [ 16 ] synthesized a new oil-soluble polymer by suspension polymerization using methyl styrene, methyl methacrylate, stearyl acrylate, and dimethyl 2,2 azobis isobutyrate as raw materials, which effectively improved the yield point of OBDFs under 180 °C conditions.…”

“…However, polymer-based rheology modifiers have a significant influence on the viscosity of drilling fluids, and this situation is not conducive to the regulation of rheology under high-density conditions. In our previous study [ 18 ], the reaction product of ethylene glycol amine with dimer acid was used as a rheology modifier, which greatly enhanced the zero-shear-rate viscosity of the water-in-oil emulsion. Noah et al [ 20 ] prepared a nanocomposite rheology modifier by adding nano-zinc oxide (ZnO-NPs) and nano-calcium carbonate (nano-CaCO 3 ) to a polystyrene-butadiene rubber (PSBR) copolymer, which effectively improved the yield point (YP), apparent viscosity (AV), and plastic viscosity (PV) of the OBDFs.…”

A Molecular Dynamics Simulation of the Toluene-Water Interface in the Presence of an External Magnetic Field

“…During the past years, a great effort has been made to characterize the specifications of three types of emulsions; water-inoil (W/O) emulsion, oil-in-water (O/W) emulsion, and multiple emulsion (Langevin et al 2004;Souleyman 2015;Kilpatrick 2012;Wong et al 2015). It is a great interest of researchers introducing the interfacial active molecules for the oil-water interface to stabilize the emulsion in different industries such as pipeline transporting (Kumar and Mahto 2017), oil based drilling fluid (Huang et al 2018), emulsion fuel in a diesel engine (Souleyman 2015), food emulsions (Andresen, 2007) and etc., (Langevin et al 2004;Ruiz-Morales and Mullins 2015). Using emulsifying agent forms a stable emulsion based on the different mechanisms; delay in coalescence and creaming due to forming the film coating around each droplet of dispersed phase, retarding the movement of droplets due to increment in viscosity of continuous phase, and etc., ……”