Abstract: A method of fracture fluid clean-up from a fracture by assisting Darcy flow with electro-osmotic effects is provided. Proppants having suitable surface potential, and fracture fluids having suitable electrical conductivity are employed. A suitable electric field is imposed, using electrodes placed on the surface or in adjacent wells. The current creates an electro-osmotic flow that carries fluid to the wellbore.

Abstract: Systems and methods are disclosed for accurately determining a pore pressure of a subsurface formation (20) penetrated by a wellbore (40). The systems and methods provide for measuring pressure and temperature at a measuring location proximal to the wellbore for a predetermined amount of time, storing the measurements, communicating the measurements and processing the pore pressure from the pressure and temperature measurements. The measuring location may be a location in a channel (50) drilled from the wellbore into the formation.

Abstract: A method is given for improving the clean-up of fracture fluid from a fracture by assisting Darcy flow by electro-osmotic effects. Proppants having suitable surface potential, and fracture fluids having suitable electrical conductivity are chosen. Then a suitable electric field is imposed, using electrodes placed on the surface or in adjacent wells. The current creates an electro-osmotic flow that carries fluid to the wellbore.

Abstract: Methods and systems are described for measuring effects of a hydraulic fracturing process. The techniques can utilizes cross-well seismic technology, such as used in Schlumberger's DeepLook-CS tools and service, or in some case surface to borehole or borehole to surface seismic technology. The downhole seismic sources at known locations can be conventional sources or can be other types of equipment operating at known locations such as perforation guns. The source is activated or swept creating energy which is transmitted through the formation. The energy is recorded at the receiver array and processed to yield a tomographic image indicating changes in the subterranean formation resulting from the hydraulic fracturing process. The process can be performed pre and post hydraulic fracture stimulation to generate a difference image of propped fractures in the reservoir.

Abstract: Embodiments of the present invention relate to systems and methods for accurately determining a pore pressure of a subsurface formation (20) penetrated by a wellbore (40). More specifically, but not by way of limitation, embodiments of the present invention may provide for measuring pressure and temperature at a measuring location proximal to the wellbore for a predetermined amount of time, storing the measurements, communicating the measurements and processing the pore pressure form the pressure and temperature measurements. The measuring location may be a location in a channel (50) drilled from the wellbore into the formation.

Abstract: The invention relates to oil production stimulation methods and can be used for both reservoirs with fractures resulting from the fracturing procedure and reservoirs with naturally occurring fractures, for which the fracturing procedure is not mandatory. A material which expands while hardening or setting, is injected into the near-wellbore region of a cased well, into the space between the casing and the reservoir, and the wellbore is then perforated. A material having an expansion degree sufficient for application of pressure to the wellbore walls and for keeping at least one fracture open is used as the material which expands while hardening or setting. After the perforation has been done, the reservoir is hydraulically fractured. For naturally fractured reservoirs, the fracturing procedure is not mandatory.

Abstract: The methods of evaluating a geometry of a hydraulic fracture in a rock formation penetrated by a borehole comprises the steps of measuring the values of electric or magnetic fields, or both electric and magnetic fields generated due to the electrokinetic effect by the flow of an electrolyte-based fracturing fluid from the borehole into the fracture and from the fracture into the formation or by the reverse flow of the fluid from the rock formation and from the fracture into the borehole and determining the geometry of the fracture from the measured values. The methods may provide for varying the injection pressure, varying the value of the electrokinetic coupling coefficient of the fracturing fluid or applying at least one pressure pulse of a given magnitude to the fracturing fluid.

Abstract: A method for stabilising an unconsolidated zone (18) of a borehole, by forming a region of the borehole having enlarged diameter (22) in the unconsolidated zone; positioning a fluid-filled casing (26) in the borehole the liner having a pipe (28) extending therethrough into a lower portion; pumping cement from the surface inside the pipe so as to exit the liner at the lower portion and flow upwards to fill the annulus (44) formed between the outside of the liner and the borehole in the unconsolidated zone; withdrawing the pipe (28) from the casing while pumping fluid therethrough so as to maintain the liner substantially fluid-filled and to displace cement above the liner in the adjacent region; drilling through the cement and liner in the unconsolidated zone after the cement has set.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: The invention relates to monitoring of fluid-filled domains in various media including, for example, subterranean formations, construction elements, bones. Claimed are a method for determining characteristic sizes of a fluid-filled crack in a medium and a system for implementation thereof. In accordance with this method, oscillations of the fluid-filled crack are registered. Wave characteristics of standing interface waves propagating along the fluid-filled crack surfaces are determined based on the registered oscillations taking medium and fluid properties into account. The fluid-filled crack characteristic sizes are calculated based on the determined wave characteristics of the standing interface waves.

Abstract: Cementing compositions for oil wells or the like comprise between 30% and 100% (by weight of cement) of rubber particles, with grain size in the 40-60 mesh range. Adding rubber particles in accordance with the invention produces a low density slurry while keeping the cement permeability low. Compositions of the invention are particularly advantageous for cementing zones subjected to extreme dynamic stresses such as perforation zones and the junctions of branches in a multi-sidetrack well.

Abstract: The present invention provides cementing compositions for oil wells or the like comprising an hydraulic binder and reinforcing particles constituted by a flexible material of low compressibility, and with an average grain size of less than 500 microns. The compositions of the invention are of particular advantage when cementing zones which are subjected to extreme dynamic stresses, such as perforation zones and the junctions of a multi-branch lateral well. They are also highly suitable for producing plugs.

Abstract: A method of evaluating the geometry of a hydraulic fracture in a rock formation comprises the steps of: obtaining measured values of electric and/or magnetic fields induced by the forward or back propagation of a fracturing fluid between the fracture and the rock formation; and determining the geometry of the fracture from the measured values.

Abstract: A method for stabilising an unconsolidated zone (18) of a borehole, by forming a region of the borehole having enlarged diameter (22) in the unconsolidated zone; positioning a fluid-filled casing (26) in the borehole the liner having a pipe (28) extending therethrough into a lower portion; pumping cement from the surface inside the pipe so as to exit the liner at the lower portion and flow upwards to fill the annulus (44) formed between the outside of the liner and the borehole in the unconsolidated zone; withdrawing the pipe (28) from the casing while pumping fluid therethrough so as to maintain the liner substantially fluid-filled and to displace cement above the liner in the adjacent region; drilling through the cement and liner in the unconsolidated zone after the cement has set.

Abstract: The present invention provides cementing compositions for oil wells or the like comprising an hydraulic binder and reinforcing particles constituted by a flexible material of low compressibility, and with an average grain size of less than 500 &mgr;m.

Abstract: The present invention provides cementing compositions for an oil well or the like, comprising an hydraulic binder, dense particles with a density higher than the density of the hydraulic binder, and reinforcing particles with a density of less than 1.5 g/cm3, preferably less than 1.2 g/cm3, constituted by a flexible material or rubber, of low compressibility and with an average grain size of less than 600 &mgr;m. The compositions of the invention are of particular advantage when preventing zones which are subjected to extreme stresses, such as perforation zones and the junctions of a multi-branch lateral well. They are also highly suitable for producing plugs.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: Cementing compositions for oil wells or the like comprise between 30% and 100% (by weight of cement) of rubber particles, with grain size in the 40-60 mesh range. Adding rubber particles in accordance with the invention produces a low density slurry while keeping the cement permeability low. Compositions of the invention are particularly advantageous for cementing zones subjected to extreme dynamic stresses such as perforation zones and the junctions of branches in a multi-sidetrack well.

Abstract: The present invention provides cementing compositions for oil wells or the like comprising an hydraulic binder and reinforcing particles constituted by a flexible material of low compressibility, and with an average grain size of less than 500 &mgr;m. The compositions of the invention are of particular advantage when cementing zones which are subjected to extreme dynamic stresses, such as perforation zones and the junctions of a multi-branch lateral well. They are also highly suitable for producing plugs.

Abstract: A novel test specimen configuration and modified ring test method for determining the fracture toughness, K.sub.Ic, using rock core is disclosed. The use of a truncated hollow cylindrical specimen under compressive load avoids the development of a large process zone (microcracked region) during testing, thus allowing accurate fracture toughness measurements on subsized specimens. Results using soft sandstones and Indiana limestone validate the procedure.