Method and assembly for producing oil and/or gas through a well traversing stacked oil and/or gas bearing earth layers

A method of producing oil and/or gas through a well traversing stacked oil and/or gas bearing earth layers the method comprising:

• assessing locations along the length of the well where the well path traverses said stacked oil and/or gas bearing earth layers;
• mounting a plurality of expandable packers and integrated perforating gun and sandscreen assemblies on a production t such that when the production tubing is installed within the well each integrated perforating gun and sandscreen assembly is located adjacent an oil and/or gas bearing earth layer and at least one expandable packer is located between each pair of adjacent oil and/or gas bearing earth layers;
• providing the production tubing with at least one inflow opening adjacent to each sandscreen assembly;
• installing the production tubing within the well such that each integrated perforating gun and sandscreen assembly is located adjacent an oil and/or gas bearing earth layer and at least one expandable packer is located between each pair of adjacent oil and/or gas bearing earth layers;
• inducing each expandable packer to expand and provide an annular seal between the outer surface of the tubing and the inner surface of the wellbore or wellbore casing;
• firing the perforation gun assemblies such that each perforating gun assembly shoots a perforation into the wellbore casing and/or surrounding oil and/or gas bearing layer;
• and
• producing oil and/or gas by inducing oil and/or gas to flow from each oil and/or gas bearing layer via the perforations through the sandscreen assemblies and inflow openings into the interior of the production tubing,
• wherein at least one sandscreen assembly is substantially tubular and is penetrated by at least one perforating gun comprising an explosive charge that is arranged within a cup shaped gun shroud with a bottom that is secured to the production tubing, a tubular side wall that extends through an opening in the tubular sandscreen assembly and a firing mouth that is arranged in an annular space between the outer surface of the tubular sandscreen and an inner wall of the well or of a well casing or well liner.