Abstract: A downhole tool comprising a body made of aluminum material, dissolvable material or light alloy material having a coating formed by the plasma electrolytic oxidation process. The tool is a slip, a drag block, a button or any tool with wear blocks to get drag or keep the tool centered.

Abstract: A dissolvable plug for plugging oil and gas well casings to perform treatment and other downhole operations is disclosed. The plug is attached to a setting tool and lowered downhole. The setting tool is fired to cause the plug to engage the casing and to release the setting tool. A ball is dropped to close the passage through the plug. Hydraulic pressure is applied on the ball from above and the plug expands outwards to create a seal between the plug and the casing. After operations above the plug are completed, the ball and the plug are dissolved by the surrounding fluids.

Abstract: An apparatus and a method for cementing a casing in various elevations is disclosed. A casing string having at least one cementing valve is lowered into a borehole. In the closed position, the valve prevents fluid communication between the interior and exterior of the casing. In the opened position, the valve allows fluid communication between the interior and the exterior of the casing so that cement is pumped therethrough to cement the borehole adjacent the valve at the borehole elevation where the valve is located. Opening of the valve is effected by landing on the valve an opening dart having a unique profile corresponding to the valve and applying pressure on the dart to move a sleeve in the valve to a first position exposing radial ports in the casing. The valve is closed by landing a dart on the opening dart and applying pressure thereon to move the sleeve to a second position to close the ports.

Abstract: A stop collar assembly includes an inner sleeve and two end rings. The stop collar assembly is received over a tubular member and is securely attached thereto by slidingly advancing the two end rings toward each other over the inner sleeve and applying a compression force on the exterior of the inner sleeve.