The invention belongs to the oil industry and can be used for enhanced oil recovery by formations' yielding to the fullest extent possible under complicated mining and geological conditions. The method of repeated completion of the production formations by helicoid perforation includes perforation, which is performed by moving the perforator along well axis and simultaneously rotating it around its axis with making perforation channels, provided that the speeds of movement and rotation of the perforator are selected based on the condition that the perforation obtained as a result is a helicoid with creation an empty space in the processed formation, wherein hydraulic perforating cap (hydraulic perforator) is used as perforator and the pitch of the obtained helicoid is 10 cm, besides Helicoid pitch is 0.7 of the maximum slot height.

The perforation channels are joined with each other in the formation due to small helicoid pitch and in casing string annulus a cylindrical mine working with radius over 0.5 m is created. The area of fluid filtration from the formation to the well is 5 times more than for open well bore, which leads to decreasing skin factor to the level of hydraulic fracturing of formation without destroying formation top and bottom or bridging inside the formation. The invention allows creating well open bottom-hole (cavity) of radius over 0.5 m and decreasing filtration resistances, decreasing risk of "shutdown" during hydraulic fracturing of formation and increasing filtration efficiency. 1 dependent claim, 2 illustration.

A pressure equalization valve for a treatment tool (51) movable in a completion string (12). The valve comprises a cylindrical valve body having an axial bore (110) in fluid communication with the treatment tool (51). A cylindrical shuttle (112) is provided axially and sealably movable in the axial bore (110). The shuttle (112) is operable between a closed position and an open position. When a flow rate of the fluid flowing from the treatment tool (51) exceeds a preset rate to overcome the spring (114) biasing, the shuttle (112) shifts to the closed position. When the flow rate from the treatment tool (51) drops below the preset rate, the shuttle (112) is biased to the open position.

A zonal isolation device (10; 20; 30; 300; 400; 500; 600) in the form of an active external casing packer is provided which includes a tubular section such as a casing or liner (1; 21; 31; 171; 203) arranged to be run into and secured within a larger diameter generally cylindrical structure such as an open borehole (163; 213). At least one sleeve member (3; 23; 33; 43; 173) is positioned on the exterior of the casing or liner and is sealed thereto and at least two deformable band members (201; 401, 403; 501) are provided around and are bonded to the outer circumference of the sleeve member. The sleeve member and the at least two deformable band members is/are expanded into place against the inner circumference of the open borehole by increasing the pressure within the sleeve member. The method detailed herein also provides zonal isolation by use of a pair of spaced apart sleeve members during a frac operation where frac fluid is supplied to a zone (in between the pair of sleeve members) requiring to be frac'd, where the frac pressure acts not only on the outside of the zonal isolation device but also on the interior of the sleeve member to enhance the seal provided thereby.

A zonal isolation device (10; 20; 30; 300; 400; 500; 600) in the form of an active external casing packer is provided which includes a tubular section such as a casing or liner (1; 21; 31; 171; 203) arranged to be run into and secured within a larger diameter generally cylindrical structure such as an open borehole (163; 213). At least one sleeve member (3; 23; 33; 43; 173) is positioned on the exterior of the casing or liner and is sealed thereto and at least two deformable band members (201; 401, 403; 501) are provided around and are bonded to the outer circumference of the sleeve member. The sleeve member and the at least two deformable band members is/are expanded into place against the inner circumference of the open borehole by increasing the pressure within the sleeve member. The method detailed herein also provides zonal isolation by use of a pair of spaced apart sleeve members during a frac operation where frac fluid is supplied to a zone (in between the pair of sleeve members) requiring to be frac'd, where the frac pressure acts not only on the outside of the zonal isolation device but also on the interior of the sleeve member to enhance the seal provided thereby.

Systems and methods for monitoring a wellbore and actuating a downhole device include a body adapted for insertion into the wellbore that contains a processor, data storage, and sensors that detect a pressure, temperature, and acceleration associated with the body. Computer instructions are usable to receive and store preselected parameters, which include pressure, temperature, and acceleration ranges, and to compare measured values to these ranges for forming a determination usable to initiate actuation of a downhole tool. Additional parameters, such as temporal parameters, can be used to allow, cease, reset, or prevent actuation of the downhole tool.