An additive for reducing filtrate loss may be obtained by the reaction of carboxymethyl cellulose with an ethylenically unsaturated monomer containing a sulfonic group in the form of acid or salt thereof. The product of the reaction useful in water-based drilling muds which are employed in the drilling and/or completion of oil wells. The additive exhibits its characteristic function of filtrate reduction even at high temperature and pressure conditions; and, moreover, it is suitable for application in the presence of salts and solids.
In modern drilling technology drilling fluids are required to fulfill many different roles, such as pressure control. lubrication and cooling of the drill bit, removal of cutting from downholc locations and prevention of blowout. However the drilling of deep wells may meet highly complex and. sometimes, hazardous problems related to loss of drilling fluids. Although these losses are due mainly to the structural conditions of the geological formations drilling fluids are penetrated, filtrate reducer additive with cement material used in drilling fluid formulations may play an important role in the solution to this problem. Owing to increasingly severe conditions are encountered in oil exploration it is desirable to improve the conventional lubricating action of water-based drilling fluid for reducing energy dissipation and drillstring wear.
Filtrate reducers used to reduce fluid loss to the formation caused by the liquid phase of the drilling fluid. Our filtration reducers can be formulated to work effectively in bottomhole temperatures as high as 500 degF [260 degC]. Drilling fluids must be able to form a solid filtercake on the wellbore wall which prevents the flow of fluid into the formation. Bentonite clays can be used in water-based drilling fluids as highly-effective fluid loss control agents. Bentonites swell in water , releasing plate-shaped clay particles only a few nanometres thick and with extremely high aspect ratio. These rapidly form a thin, strong and almost impermeable filtercake through which drilling fluids cannot pass.