The present invention relates to a geothermal energy extraction subterranean system for extracting heat from a subterranean formation, comprising an injection well comprising a first well tubular metal structure arranged in a first borehole providing a first annulus therebetween and extending from surface into the subterranean formation and being configured to inject a working fluid out through a first injection opening into a production area defined in the subterranean formation and thereby generating a heated working fluid, and a first production well comprising a second well tubular metal structure arranged in a second borehole providing a second annulus therebetween and extending from surface into the subterranean formation into the production area and extracting the heated working fluid through a first production opening, wherein the first well tubular metal structure of the injection well comprises a first annular barrier and a second annular barrier configured to expand in the first annulus to abut a wall of the first borehole to isolate a production zone in the production area, each annular barrier comprising a tubular metal part mounted as part of the first well tubular metal structure, the tubular metal part having a first expansion opening and an outer face, an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing the wall of the borehole, each end of the expandable metal sleeve being connected with the tubular metal part, and an annular space between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being expanded to abut a wall of the first borehole by entering pressurised fluid into the annular space through the first expansion opening, the first injection opening being arranged in the first well tubular metal structure between the first annular barrier and the second annular barrier, and the first production zone being arranged between the first well tubular metal structure and the second well tubular metal structure so that the heated working fluid is extracted in the second well tubular metal structure through the first production opening. The present invention furthermore relates to a geothermal energy extraction subterranean method for extracting heat from a subterranean formation by means of the geothermal energy extraction subterranean system according to the present invention.

Embodiments of the invention utilize the geothermal energy exchanger and battery (GEEB) to recover and store thermal energy from the dwelling, from the ground, and from the Earth's atmosphere, reuse the thermal energy in another season of the year, and consume electrical energy to heat and cool the structure at electrical Off Peak time periods. The GEEB may be constructed of a compact steel, ribbed and waterproof permanent container that is set at a depth beneath the surface of the ground where the normal soil temperature is virtually constant year round. The container can then be encased in poured concrete, with the exception of piping or conduits. The container is then filled with a heat transfer fluid so that the entire thermal mass of the GEEB and heat transfer fluid reaches the ambient ground temperature and efficiently couples the load and source sides of a heating and cooling system.

A method for extracting geothermal energy from a geothermal reservoir formation. A production well is used to extract brine from the reservoir formation. At least one of nitrogen (N.sub.2) and carbon dioxide (CO.sub.2) may be used to form a supplemental working fluid which may be injected into a supplemental working fluid injection well. The supplemental working fluid may be used to augment a pressure of the reservoir formation, to thus drive a flow of the brine out from the reservoir formation.

A grout used in horizontal directional drilling including a silica material present in an amount of from about 50% to about 70%, bentonite present in an amount of from about 20% to about 30%, a carbon source present in an amount of from about 5% to about 15%, an inorganic alkaline material present in an amount of from about 0% to about 3%, a fluid loss additive present in an amount of from about 0% to about 1%, a polymeric dispersant present in an amount of from about 0% to about 1%, and a polymeric flow enhancer present in an amount of from about 0% to about 0.5%, all by weight of the grout composition. Methods utilizing the grout include placing conduit in a hole, forming the grout slurry, and placing the grout slurry adjacent to the conduct.

A method of forming a set grout includes steps of preparing a grout additive fluid comprising a fresh water base fluid and a grout additive control package comprising a primary additive selected from the group consisting of an inhibitor, a dispersant, a thermally conductive material, and any combination thereof; introducing an aqueous swellable clay into the grout additive fluid, thereby forming a final grout fluid; and introducing the final grout fluid into an annulus in a subterranean formation, the annulus formed between an exterior of a geothermal well loop tubular and the subterranean formation. The ordering of additives in the method results in enhanced effectiveness of the additives, which may reduce the amount of additive loading required.

A geo-energy production system and method is disclosed for extracting thermal energy from a reservoir formation, and for storing at least one of thermal waste heat or excess heat in a storage zone of the reservoir formation. The system may at least one compressed fluid injection well in communication with the storage zone for injecting an unheated, compressed working fluid into the storage zone. The system may also have at least one fluid injection well in communication with the storage zone for injecting a working fluid laden with thermal waste heat or excess heat, into the storage zone, the storage zone being located below a caprock layer of the reservoir formation and above a zone of native brine within the reservoir formation. The storage zone is at least partially circumscribed by a hot brine storage zone of the reservoir formation. The compressed working fluid further assists with a withdrawal of pressurized brine residing below and/or to the sides of the storage zone. At least one compressed CO.sub.2, N.sub.2, or air energy storage production well is used, which is in communication with the storage zone for removing compressed working fluid from the storage zone for use in power production.

An assembly and process for forming a two stage extruded pipe having a central inner sleeve and a pair of outer attached lobes. The central sleeve shaped (also termed a grout receiving tube) is produced in an initial extrusion operation, following which it enters a cross head operation where a pair of outer lobes are attached to cross sectional exterior surface locations according to a second stage extrusion operation so as to be integrally formed therewith. Other steps include cooling of the dual stage extruded pipe, as well as sectioning and stacking the pipe. Additional steps include forming elongated slots or apertures into the central sleeve portion of the finished extrusion, such in non-interfering fashion with the individual passageway defining and lobes.

A process for producing power including injecting a first heat transfer fluid through an injection well to a geothermally-heated formation that contains a second heat transfer fluid. The first heat transfer fluid may then be heated via indirect heat exchange in an interwell run fluidly connected to the injection well and disposed within the geothermally-heated formation. The heated first heat transfer fluid may then be recovered through a production well fluidly connected to the interwell run. Thermal energy contained in the recovered heated first heat transfer fluid may then be converted in a power production unit fluidly connected to the injection well and the production well. The interwell run, in some embodiments, may include multiple heat exchange tubes disposed within a perforated casing or drill pipe.

The boiling-water geothermal heat exchanger 1 is provided with a water injection pipe 2 which is installed underground and to which water is supplied from the ground and a steam extraction pipe 3 which is installed underground so as to be in contact with the water injection pipe 2 and has a plurality of ejection ports 5, in which a pressure inside the steam extraction pipe 3 is reduced to the vicinity of a pressure required by a turbine 6, high-pressure hot water which is produced by supplying heat from a geothermal region 4 to water inside the water injection pipe 2 is changed to a single-phase flow of steam inside the steam extraction pipe 3 present underground via the ejection ports 5, and the single-phase flow of steam is extracted on the ground. And in the boiling-water geothermal heat exchanger 1, a heat insulation portion is formed at a part which is in contact with a low-temperature region close to the ground surface, and the heat insulation portion is such that the level of water supplied to the water injection pipe 2 is lowered to form an air layer at an upper part of the water injection pipe 2.

A method and apparatus for efficiently extracting geothermal energy from a subterranean thermal reservoir through a wellbore where the heat exchange fluid is introduced at a slower velocity than the velocity at which the fluid is extracted. The method and apparatus further comprises a region void of cement between the outer wall of a casing and the inner wall of the wellbore, such that thermally conductive material can be injected therein.