Process for downhole heating

Abstract

Neutral electrolytes, relatively neutral electrolytes, metal oxides, metal hydroxides and/or organic exothermic hydration chemicals may be hydrated with water at a controlled location in a subterranean formation to generate sufficient exothermic heat to at least soften and possibly melt and flow bitumen at or near the location. This controlled and localized heating would be useful in drilling through relatively thick bitumen or “tar” beds. In one non-limiting embodiment the exothermic hydration reaction does not generate appreciable amounts of gas. Alternatively, the exothermic reaction may be used to liberate hydrocarbons from gas hydrates in an embodiment where the evolution of gas is acceptable.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. provisional application No. 60 / 614,129 filed Sep. 29, 2004.FIELD OF THE INVENTION [0002] The present invention relates to methods and compositions for providing controlled downhole heating, such as in a subterranean reservoir during a hydrocarbon recovery operation. BACKGROUND OF THE INVENTION [0003] Drilling fluids used in the drilling of subterranean oil and gas wells along with other drilling fluid applications and drilling procedures are known. In rotary drilling there are a variety of functions and characteristics that are expected of drilling fluids, also known as drilling muds, or simply “muds”. The drilling fluid is expected to carry cuttings up from beneath the bit, transport them up the annulus, and allow their separation at the surface while at the same time the rotary bit is cooled and cleaned. A drilling mud is also intended to reduce friction between the drill string and the sides...

AI Technical Summary

Benefits of technology

[0013] In carrying out these and other objects of the invention, there is provided, in one non-limiting form, a method for providing localized heating in a subterranean formation that involves placing at a location in the subterranean formation in any order: an exothermic hydration chemical and an amount of water in contact with the exothermic hydration chemical effective to cause an exothermic reaction thereby heating the location and a suitable medium for transporting the heat source to the desired location.

[0014] In another non-limiting embodiment there is created a method for providing localized heating in a subterranean formation that involves placing at a location in the subterranean formation where bitumen is present in any order: an exothermic hydration chemical and an effective amount of water in contact with the exothermic hydration chemical to cause an exothermic reaction without generating an appreciable amount of gas; and heating the location sufficiently to at least soften the bitumen.

Problems solved by technology

Because drilling fluids are called upon to perform a number of tasks simultaneously, this desirable balance is not always easy to achieve.

Drilling through thin bitumen beds is generally no more than a minor nuisance, but thick beds can result in stuck pipe, stuck casing, side-tracks, loss of hole and other problems that can cost the well operators millions of dollars.

One of the most precarious operations is running casing after drilling through a bitumen bed due to the movement or “flow” of the bitumen into the borehole before casing can be picked up and run to bottom.

This stability is limited by temperature and pressure: gas hydrates are stable at low temperatures and / or high pressure.