BACKGROUND

The present disclosure relates to systems and methods for extracting a produced material from a subterranean formation that includes shale.

Operations to extract a subterranean product from the earth through a well often use borehole fluids to facilitate or implement the operations. Hydrocarbons, such as oil and gas, are subterranean products commonly extracted from reservoirs, areas of the earth that contain the hydrocarbons. A reservoir may be deep below the surface of the earth and the earth may include one or more formations that are above and/or make up the reservoir. A formation is a region of the earth with a distinct lithology describing the physical characteristics of the rock in the formation, such as mineral content. For example, a formation may include shale, a sedimentary rock which may include one or more materials that is reactive to water, such as by swelling upon contact with water.

Illustrative extraction operations may include, for example, drilling, completion, stimulation, and production. Stimulation operations may include, for example, fracturing and acidizing. In drilling, a drill bit is used to drill a borehole into the earth. A borehole fluid may be used with the drill bit to advance the borehole beneath the surface of the earth. For example, a drilling fluid, or “mud”, may be circulated in the borehole with the drill bit to facilitate the drilling operation. As the drilling progresses it produces cuttings, which are small pieces of the formation through which the drill bit is progressing. The various functions of the drilling fluid include removing drilling cuttings from the borehole, cooling and lubricating the drill bit, aiding in support of the drill bit and the drill pipe which supports the drill bit, and providing a hydrostatic head to maintain the integrity of the borehole walls and prevent well blowouts.

During drilling of subterranean boreholes, various formations that include reactive shale may be encountered. Reactive shales may be problematic during drilling operations, for example, due to their tendency to transform when exposed to water-based drilling fluids, such as by swelling. The transformation of the shale may interfere with attempts to maintain the integrity of drilling cuttings traveling up the borehole until such time as the cuttings can be removed by solids control equipment located at or above the surface.

One technique used to counteract the propensity of water-based drilling fluids to interact with reactive shales in a formation involves the use of an additive that acts as a shale inhibitor. Potassium chloride is a common shale inhibitor. However, potassium chloride may be only moderately effective at inhibiting shale swelling in some cases. Further, in certain areas of the world, use of some shale inhibitors may be restricted, such as a restriction on potassium ions.

