Magnesium Peroxide & Calcium Peroxide in Oil Field application

In this field, a polysaccharide polymer is often used to either fracture the rock or form a filter cake. After

drilling mud
the polymer achieves its purpose, it must be degraded to lower its viscosity so that it can be easily removed.Products that are used in this field to lower the viscosity of these polymers are called breakers.The challenge in the selection of a breaker is to use a product that will remain inactive until the polymer performs its function and then causes a rapid degradation of the polymer. Calcium Peroxide and Magnesium Peroxide have unique advantages in this field. They are very slightly soluble in water and have relatively high stability to decomposition at elevated temperatures. At the desired time, these products can be activated by the addition of an acid or by other means. This results in the generation of hydrogen peroxide which is the actual oxidizing agent.Several patents and new patent applications claim the use of calcium and magnesium peroxide in this field. The following examples are selected for illustration only. The reader should review the literature for a full list of patents to determine whether the intended application is coveredby a patent in the country of application.

Fracturing fluids

drilling fluid

US 5,253,711 claims the addition of calcium or magnesium peroxide as a component of a fracturing fluid. The products are then activated by heat. Magnesium peroxide achieves a delayed break at high temperatures whereas lower temperatures activate calcium peroxide.
US 200,309,251 and US 6,488,091 claim the use of calcium or magnesium peroxide in fracturing fluids of different compositions and processes.
US 5,624,886 claims the use of alkaline earth metal peroxides for fracturing of subterranean formation. The products are granulated into a pellet or prill.

Filter cake removal

US 5,238,065 claims the destruction of filter cakes using solutions containing calcium or magnesium peroxide together with an acid. The acid activates the peroxide at the desired time.
US 5,697,905 and US 6,494,263 claim the incorporation of magnesium peroxide as a breaker in different filter cake compositions. At the appropriate time, an activator solution is used to release hydrogen peroxide from magnesium peroxide.
US 6,138,760 claims the incorporation of magnesium peroxide in a pretreatment fluid which is introduced prior to the polymer containing fluid. This enhances degradation of the polymer in the filter cake from the reservoir side of the filter cake during flow back of the treatment fluid.
WO 03,054,109 claims the encapsulation of an inorganic peroxide in order to improve its stability while embedded in the filter cake and reduce premature degradation of the polymer. At the appropriate time, pH is decreased in order to activate the inorganic peroxide.

Well cementing

US 5,613,558 claims the use of calcium or magnesium peroxide in a well cementing composition. The composition contains hydraulic cement, and a cement hydration retarder. The role of the peroxide is to degrade the retarder over a period of time.