Effect of Two Types of Fly Ash on Rheological and Filtration Properties of Water-Based Drilling Mud

Emine Yalman,Tolga Depci̇,Gabriella Federer-Kovacs

doi:10.28978/nesciences.1036853

Abstract

In this study, the usage of class F fly ash (brown coal) and class C fly ash (lignite) with increasing concentration in water based mud mainly composed of bentonite dispersion was investigated at ambient conditions. Experimental results indicate that efficiency of the mud is significantly controlled by type of the fly ash tested and its concentrations. The results show that Class F fly ash enhanced filtration properties (filtrate loss and mud cake) of the mud and have no effect on the rheology including, yield point, viscosity whereas the class C fly ash increased the rheology parameters and degraded water loss into the formation and filer cake thickness dramatically. This study showed that class F fly ash displays superior performance than class C fly ash. Through this study, it was reveal that class F fly ash is a promising additive to improve the filtration characteristics of bentonite based drilling fluids, thereby contributing to reducing formation damage caused by drilling mud.

Highlights

Drilling mud is an indispensable component of drilling process
Elemental composition of both types fly ash samples used were measured with Rigaku Supermini 200 type XRF spectrometer
The results show that the chief differences between two samples is amount of silica, alumina and iron contained in them, as expected

Summary

Introduction

Drilling mud is an indispensable component of drilling process. It performs many important functions including cleaning bottom of the well, balancing formation pressure, minimizing formation damage, controlling corrosion, maintaining the stability of the well, suspending cuttings, ensuring adequate formation evaluation, as well as lubricating and cooling drilling string and bit. Fly ash or flue ash is a waste obtained from pulverized coal combustion in coal-fired power plants. An ASTM standards (ASTM C618) defines mainly Class F and Class C considering their composition. The main difference between these two types of fly ashes is amount of SiO2, Al2O3, and Fe2O3 they contain. While harder anthracite or bituminous coals produce Class F fly ash, lignite or sub-bituminous, which are the lowest grade of coal, produce Class C fly ash

Objectives

Methods

Results