The invention provides a downhole borehole traction apparatus (10) and method of use. The apparatus comprises a body comprising a borehole engaging section wherein the borehole engaging section comprises an outer surface comprising at least one thread. The at least one thread comprises a crest surface (32), a leading surface (30), and a trailing surface (28) having a curvilinear shape. The at least one thread has a low pressure generation means comprising one or more formations.

The invention provides a downhole borehole traction apparatus (10) and method of use. The apparatus comprises a body comprising a borehole engaging section wherein the borehole engaging section comprises an outer surface comprising at least one thread. The at least one thread comprises a crest surface (32), a leading surface (30), and a trailing surface (28) having a curvilinear shape. The at least one thread has a low pressure generation means comprising one or more formations.

A bearing capacity reinforcing device. The bearing capacity reinforcing device comprises: a reinforcing mechanism having a reinforcing body and a reinforcing disc connected to a lower portion of the reinforcing body, a plurality of reinforcing rib plates being spaced apart in a circumferential direction of the reinforcing body and connected to the reinforcing disc; wherein the reinforcing disc is provided with a plurality of accommodating spaces which are spaced apart in a circumferential direction thereof and provided therein with a movable sector plate, respectively, and the reinforcing disc at each of the accommodating spaces is provided with a perforated portion which can be blocked by the sector plate; and a connecting portion having a male buckle end connected to a lower end of the reinforcing body, and a female buckle end connected to an upper end of the reinforcing body. The present disclosure can increase the area of action between the riser or the surface conduit and the seabed soil, thereby increasing the bearing capacity of the conduit to ensure the safety and high efficiency of on-site exploration and development operations.

A bearing capacity reinforcing device. The bearing capacity reinforcing device comprises: a reinforcing mechanism having a reinforcing body and a reinforcing disc connected to a lower portion of the reinforcing body, a plurality of reinforcing rib plates being spaced apart in a circumferential direction of the reinforcing body and connected to the reinforcing disc; wherein the reinforcing disc is provided with a plurality of accommodating spaces which are spaced apart in a circumferential direction thereof and provided therein with a movable sector plate, respectively, and the reinforcing disc at each of the accommodating spaces is provided with a perforated portion which can be blocked by the sector plate; and a connecting portion having a male buckle end connected to a lower end of the reinforcing body, and a female buckle end connected to an upper end of the reinforcing body. The present disclosure can increase the area of action between the riser or the surface conduit and the seabed soil, thereby increasing the bearing capacity of the conduit to ensure the safety and high efficiency of on-site exploration and development operations.

A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter. The outer surface of the body (10) further comprises a low pressure generation means (50) located in between the two longitudinally spaced apart bearing surfaces (30U; 30D) for generating a region of lower pressure in the downhole fluid within that region compared to the said certain pressure. A method of cleaning a downhole borehole is also described involving miming in a work string comprising a downhole borehole cleaning tool (10) into a borehole to be cleaned, and permitting or arranging for relative movement to occur between the downhole borehole cleaning tool (10) and fluid located in the annulus (15) in the borehole (16) whereby drill cuttings are recirculated.

A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter. The outer surface of the body (10) further comprises a low pressure generation means (50) located in between the two longitudinally spaced apart bearing surfaces (30U; 30D) for generating a region of lower pressure in the downhole fluid within that region compared to the said certain pressure. A method of cleaning a downhole borehole is also described involving miming in a work string comprising a downhole borehole cleaning tool (10) into a borehole to be cleaned, and permitting or arranging for relative movement to occur between the downhole borehole cleaning tool (10) and fluid located in the annulus (15) in the borehole (16) whereby drill cuttings are recirculated.

The present invention relates to a downhole production casing string for insertion in a borehole in a reservoir, the downhole production casing string having a first end nearest a top of the borehole and a second end furthest away from the top, the downhole production casing string extending along a longitudinal axis and comprising at least one opening which during production allows hydrocarbon-containing fluid from the reservoir into the downhole production casing string, a plurality of casing parts having end sections and a base section between the end sections, the base section having an outer diameter, and at least one annular projecting element having an outer face and at least one helical groove arranged in or on the outer face and having an overall outer diameter which is larger than the outer diameter of the base section. Furthermore, the invention relates to a downhole production casing string system for completing a well downhole and to a method of implementing a production casing string according to the invention.

The present invention relates to a downhole production casing string for insertion in a borehole in a reservoir, the downhole production casing string having a first end nearest a top of the borehole and a second end furthest away from the top, the downhole production casing string extending along a longitudinal axis and comprising at least one opening which during production allows hydrocarbon-containing fluid from the reservoir into the downhole production casing string, a plurality of casing parts having end sections and a base section between the end sections, the base section having an outer diameter, and at least one annular projecting element having an outer face and at least one helical groove arranged in or on the outer face and having an overall outer diameter which is larger than the outer diameter of the base section. Furthermore, the invention relates to a downhole production casing string system for completing a well downhole and to a method of implementing a production casing string according to the invention.

A reactive torque automatic balancing device for a screw drilling tool includes an upper joint (1); a core cylinder (9) having an inner chamber in communication with the screw drilling tool (305) located downstream, so that drilling fluid from the inner chamber of the upper joint (1) flows to the screw drilling tool (305) through the inner chamber of the core cylinder (9) to allow the screw drilling tool to perform drilling; a lower joint (16) fixedly arranged at a lower end of the core cylinder (9); and an automatic balancing assembly, which is arranged between an outer wall of the core cylinder (9) and an inner wall of the upper joint (1), and driven by hydraulic pressure generated by a part of the drilling fluid flowing through the inner chamber of the upper joint (1).

A reactive torque automatic balancing device for a screw drilling tool includes an upper joint (1); a core cylinder (9) having an inner chamber in communication with the screw drilling tool (305) located downstream, so that drilling fluid from the inner chamber of the upper joint (1) flows to the screw drilling tool (305) through the inner chamber of the core cylinder (9) to allow the screw drilling tool to perform drilling; a lower joint (16) fixedly arranged at a lower end of the core cylinder (9); and an automatic balancing assembly, which is arranged between an outer wall of the core cylinder (9) and an inner wall of the upper joint (1), and driven by hydraulic pressure generated by a part of the drilling fluid flowing through the inner chamber of the upper joint (1).