The present invention relates to a perforating gun tube, characterized in that the tube is made of a steel alloy comprising, in addition to iron, the following alloying elements, expressed in mass percent:

TABLE-US-00001 C 0.12-0.22% Si 0.3-1.0% Mn 1.0 - 4% Cr 0.5 - 2% Mo 0.1 -1%, V 0.05 -0.2% Ti 0.02 - 0.1% and B 0.001 - 0.01%

and impurities due to melting, and that the tube has a yield strength, R.sub.P0,2 , in the range of 750 to 1100 MPa. In addition, a perforating gun having such a perforating gun tube is described.

The present invention relates to a perforating gun tube, characterized in that the tube is made of a steel alloy comprising, in addition to iron, the following alloying elements, expressed in mass percent:

TABLE-US-00001 C 0.12-0.22% Si 0.3-1.0% Mn 1.0 - 4% Cr 0.5 - 2% Mo 0.1 -1%, V 0.05 -0.2% Ti 0.02 - 0.1% and B 0.001 - 0.01%

and impurities due to melting, and that the tube has a yield strength, R.sub.P0,2 , in the range of 750 to 1100 MPa. In addition, a perforating gun having such a perforating gun tube is described.

A smart frac plug assembly including an instrument plug module with a sensor for collecting data during a hydraulic fracturing process. This assembly when used in conjunction with a wireless or tubing conveyed data logger and other related recording/processing systems, provides direct measurements of pressure, temperature, observed velocity field and/or observed acceleration field in a subsurface.

An explosive charge assembly comprises a casing, a first liner, a second liner, a first explosive charge disposed between the casing and the first liner, and a second explosive charge disposed between the first liner and the second liner. The first liner and the second liner are configured to form a single jet upon detonation of the first explosive charge and the second explosive charge.

An explosive charge assembly comprises a casing, a first liner, a second liner, a first explosive charge disposed between the casing and the first liner, and a second explosive charge disposed between the first liner and the second liner. The first liner and the second liner are configured to form a single jet upon detonation of the first explosive charge and the second explosive charge.

The invention discloses a device for testing strength and sealing performance of cement sheath after perforation, comprising a cement sheath curing maintenance simulation component, a perforation operation simulation component, and a cement sheath performance test component. By simulating the detonation effect and fluid-solid coupling effect, quantitatively testing the internal transverse crack and longitudinal crack propagation size, compressive strength and tensile strength, permeability, blowby pressure, blowby velocity and other parameters of the cement sheath, drawing the relation curve between different perforation distances and the maximum blowby pressure and permeability of the cement sheath, determining the perforation distance H.sub.p where the blowby of the cement sheath does not occur, determining the perforation distance H.sub.K to ensure the sealing of the cement sheath, and using min (H.sub.p, H.sub.K), the critical perforation distance that the cement sheath has sufficient strength to prevent blowby and meet the sealing requirements can be determined.

Some examples of the present disclosure relate to a method for washing an annulus that at least partially surrounds a casing in a well. The method comprises locating a tool inside a wellbore casing, and flowing a washing fluid from an injection aperture on the tool and into the annulus via a first casing aperture in the casing. An inflow region of the casing is created having a reduced pressure relative to the annulus, and the method involves flowing the washing fluid from the annulus and into the inflow region of the casing through a second casing aperture in the casing.

Some examples of the present disclosure relate to a method for washing an annulus that at least partially surrounds a casing in a well. The method comprises locating a tool inside a wellbore casing, and flowing a washing fluid from an injection aperture on the tool and into the annulus via a first casing aperture in the casing. An inflow region of the casing is created having a reduced pressure relative to the annulus, and the method involves flowing the washing fluid from the annulus and into the inflow region of the casing through a second casing aperture in the casing.

A downhole perforation tool includes an upper sub-assembly configured to couple to a downhole conveyance within a wellbore that is formed from a terranean surface toward a subterranean formation; a plurality of perforation sub-assemblies, where each perforation sub-assembly includes one or more perforation guns, and one or more ports configured to fluidly couple the wellbore with a bore that extends from the one or more ports to the upper sub-assembly; a main wellbore seal positioned between the upper sub-assembly and the plurality of perforation sub-assemblies, the main wellbore seal actuatable to anchor the downhole perforation tool to a casing in the wellbore; and at least one secondary wellbore seal positioned between adjacent perforation sub-assemblies of the plurality of perforation sub-assemblies, the at least one secondary wellbore seal actuatable to fluidly isolate a portion of an annulus of the wellbore from another portion of the annulus of the wellbore.

A downhole perforation tool includes an upper sub-assembly configured to couple to a downhole conveyance within a wellbore that is formed from a terranean surface toward a subterranean formation; a plurality of perforation sub-assemblies, where each perforation sub-assembly includes one or more perforation guns, and one or more ports configured to fluidly couple the wellbore with a bore that extends from the one or more ports to the upper sub-assembly; a main wellbore seal positioned between the upper sub-assembly and the plurality of perforation sub-assemblies, the main wellbore seal actuatable to anchor the downhole perforation tool to a casing in the wellbore; and at least one secondary wellbore seal positioned between adjacent perforation sub-assemblies of the plurality of perforation sub-assemblies, the at least one secondary wellbore seal actuatable to fluidly isolate a portion of an annulus of the wellbore from another portion of the annulus of the wellbore.