Non-Productive Time (NPT) is one of the major operational and fiscal challenges of the drilling process, collectively responsible for billions of dollars in hidden cost. The greatest segment of NPT is often attributed to stuck pipe events, which may be mechanical or differential in nature. The differentially stuck pipe event is due to a differential pressure gradient, which creates a vacuum-effect upon the pipe, thereby sticking the pipe to the wall of the wellbore. Differentially stuck pipe may be alleviated at relatively low costs through application of a special fluid to help free the pipe. Such fluids useful in the release of drillpipes that are stuck due to differential pressures between the wellbore and the formation are known as spotting fluids. This paper investigates a new spotting fluid that exhibits the advantage of increased effectiveness at releasing stuck pipe in the presence of drilling fluids having high densities. In addition to this increased performance, the fluid can also be combined with a thermal activator to trigger a heat-generating fluid that is capable of exotherms from 100 to 300°F, thereby providing additional performance in treating stuck pipe.
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