Abstract: This invention relates to the construction of well such as oil and gas wells using techniques based on drilling small lateral wells from a main well. The problem of narrow pressure window is solved by the use of constructions techniques that are based on the use of lateral boreholes, i.e. secondary boreholes that are drilled a main borehole, wherein a method of constructing a well comprises drilling a main borehole extending from the surface through one or more underground formations, drilling a plurality of lateral boreholes extending from the main borehole into surrounding formations, wherein the lateral boreholes are substantially shorter and of smaller diameter than the main borehole; and wherein each lateral borehole is separated from its neighboring lateral boreholes by a relatively short distance. Drilling of the lateral boreholes can be for to extend 5-60 meters from the main borehole with a diameter in the range 3.

Abstract: An apparatus for modifying the wall surface of a borehole drilled through an underground formation. The apparatus comprises a tool body that can be introduced into the borehole using a conveyance system so as to be moveable along the borehole, and one or more members arranged so as to be able to be urged against, and moved across at least part of the borehole wall in order to work the surface thereof and modify its properties. A method of modifying the wall surface comprises positioning the tool body in the borehole at a location of interest using the conveyance system, urging the members against the borehole wall with sufficient force to modify the properties of the surface thereof, and moving the members across the surface of the borehole wall.

Abstract: A subpart of a drill string is described having an outer circumferential surface which is contoured and adapted to engage the wall of the borehole with a small angle of attack while exerting during rotary drilling operations an compacting pressure on mud cake and/or cuttings present in the annulus between the drill string and the borehole.

Abstract: This invention relates to the construction of well such as oil and gas wells using techniques based on drilling small lateral wells from a main well. The problem of narrow pressure window is solved by the use of constructions techniques that are based on the use of lateral boreholes, i.e. secondary boreholes that are drilled a main borehole, wherein a method of constructing a well comprises drilling a main borehole extending from the surface through one or more underground formations, drilling a plurality of lateral boreholes extending from the main borehole into surrounding formations, wherein the lateral boreholes are substantially shorter and of smaller diameter than the main borehole; and wherein each lateral borehole is separated from its neighbouring lateral boreholes by a relatively short distance. Drilling of the lateral boreholes can be for to extend 5-60 metres from the main borehole with a diameter in the range 3.

Abstract: A subpart of a drill string is described having an outer circumferential surface which is contoured and adapted to engage the wall of the borehole with a small angle of attack while exerting during rotary drilling operations an compacting pressure on mud cake and/or cuttings present in the annulus between the drill string and the borehole.

Abstract: An apparatus for modifying the wall surface of a borehole drilled through an underground formation. The apparatus comprises a tool body that can be introduced into the borehole using a conveyance system so as to be moveable along the borehole, and one or more members arranged so as to be able to be urged against, and moved across at least part of the borehole wall in order to work the surface thereof and modify its properties. A method of modifying the wall surface comprises positioning the tool body in the borehole at a location of interest using the conveyance system, urging the members against the borehole wall with sufficient force to modify the properties of the surface thereof, and moving the members across the surface of the borehole wall.

Abstract: A subpart of a drill string is described having an outer circumferential surface which is contoured and adapted to engage the wall of the borehole with a small angle of attack while exerting during rotary drilling operations an compacting pressure on mud cake and/or cuttings present in the annulus between the drill string and the borehole.

Abstract: A method of fracturing a rock formation is provided including placing through a wellbore penetrating the rock formation propellants in a cavity located at a radial distance from the wellbore and igniting the propellants to cause a pressure sufficient to fracture the formation.

Abstract: A subpart of a drill string is described having an outer circumferential surface which is contoured and adapted to engage the wall of the borehole with a small angle of attack while exerting during rotary drilling operations an compacting pressure on mud cake and/or cuttings present in the annulus between the drill string and the borehole.

Abstract: The present invention generally relates to an apparatus and methods for improving the stability of a wellbore during drilling operations using a rotary drill string. More specifically, embodiments of the present invention provide systems and methods for enhancing the performance of the filter or mud cake layer on the wall of the wellbore as a protective and isolating layer.

Abstract: A method of forming a seal circumferentially about a liner having pre-formed openings that is positioned in a wellbore includes the steps of running a perforating device and a seal applicator into the slotted liner, the seal applicator carrying a sealing fluid and a pumping mechanism, creating an aperture through the slotted liner at the region by activating the perforating device and pumping the sealing fluid from the seal applicator through the aperture and circumferentially about the liner to form a sealing plug in the annulus between the slotted liner and the wellbore.

Abstract: A technique that is usable with a subterranean well includes communicating a fluid into a region of the well and monitoring a level of the fluid communicated via a downhole sensor. The communication is controlled in response to the monitoring.

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: An expandable sleeve for use in a well, comprises a tubular structure including an external sealing layer comprising a compliant material; an intermediate expandable tubular body made from a plastically deformable material; and an internal spring structure such as a helically wound spring; wherein the external sealing layer is disposed on the outer surface of the tubular body, and the internal spring structure is disposed inside the tubular body and acts so as to exert a radial force on the body when in an expanded state. Such a sleeve can be used to seal off perforations and in well completions using slotted liners or in drilling applications.

Abstract: A method for sealing a hole in a tubular in a wellbore comprising: (A) locating the tubular patch adjacent the hole; (B) (i) plastically expanding a first portion of the tubular patch above the hole into annular sealing engagement with the tubular to form a first annular seal and (ii) plastically expanding a second portion of the tubular patch below the hole in the tubular into annular sealing engagement with the tubular or the open hole to form a second annular seal thereby sealing the hole in the tubular. The patch may be a corrugated tube prior to expansion in order to pass through restrictions and may have a section with an increased wall thickness including a resilient seal.

Abstract: An apparatus includes a base pipe and a fluid control material. The base pipe includes openings, and the fluid control material is mounted to the pipe to control fluid communication through the openings of the pipe. The fluid control material has a permeability that may be changed to selectively control the communication of well fluid through the openings.

Abstract: A technique that is usable with a subterranean well includes communicating a fluid into a region of the well and monitoring a level of the fluid communicated via a downhole sensor. The communication is controlled in response to the monitoring.

Abstract: A subpart (430) of a drill string (211) is described having an outer circumferential surface which is contoured and adapted to engage the wall of the borehole with a small angle of attack while exerting during rotary drilling operations an compacting pressure on mud cake and/or cuttings present in the annulus between the drill string and the borehole.

Abstract: A system and method is provided for utilizing both a wellbore completion and a formation treatment system. The formation treatment system comprises a bypass that directs well treatment fluid around the wellbore completion. The bypass protects the wellbore completion from potentially corrosive or erosive well treatment fluids which, in turn, allows the wellbore completion to remain downhole during the introduction of well treatment fluids.

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.