Intake screen assembly for submersible well pump

A well fluid particle screen assembly for a well pump, comprising:

• a base pipe having axis, a first pipe segment and a second pipe segment, one of the pipe segments being above the other of the pipe segments, the base pipe having an open upper end for attachment to an intake structure of the well pump within a well and a closed lower end;
• a plurality of first perforations in a sidewall of the first pipe segment;
• a first screen mounted around the first pipe segment filtering well fluid flowing through the first screen along a first flow path through the first perforations into the first pipe segment;
• a plurality of second perforations in a sidewall of the second pipe segment, the sidewall of the second pipe segment having a solid cylindrical wall portion that is free of perforations and extending axially from the second perforations;
• a second screen mounted around the second pipe segment radially outward from the solid cylindrical wall portion of the second pipe segment, defining a second screen annulus between the second screen and the solid cylindrical wall portion of the second pipe segment;
• a cylindrical second pipe segment valve chamber wall at one end of the second screen, the second pipe segment chamber wall being concentric with and radially outward from the second perforations in the second pipe segment, defining a second pipe segment valve chamber, the second pipe segment chamber wall having one end below the second perforations and another end above the second perforations;
• a second pipe segment sleeve valve in the second pipe segment valve chamber, the second pipe segment sleeve valve having a closed position blocking flow of well fluid from the second screen annulus to the second perforations and being axially slidable along the second pipe segment valve chamber wall past the second perforations to an open position allowing flow from the second screen annulus through the second perforations;
• wherein the second pipe segment sleeve valve has an internal pressure area acted on by an internal pressure in the second pipe segment and an external pressure on the second pipe segment, creating a negative pressure differential urging the second pipe segment valve toward the open position when the interior pressure is less than the exterior pressure due to suction of the well pump, the interior and exterior pressure areas being selected such that when the negative pressure differential reaches a selected level of the interior pressure less than the exterior pressure, the negative pressure differential causes the second pipe segment valve to move from the closed position to the open position;
• and
• a second pipe segment sleeve valve retainer that retains the second pipe segment sleeve valve in the closed position until the negative pressure differential reaches the selected level, which indicates that flow through the first screen and the first set of perforations has declined due to clogging of the first screen.

A method of pumping well fluid from a well, comprising:

• mounting a base pipe to well pump intake structure of a well pump within a well, the base pipe having a first pipe segment and a second pipe segment, one of the segments being above the other of the segments, the base pipe having first and second sets of perforations in sidewalls of the first and second pipe segments, respectively, the base pipe having first and second screens mounted around the first and second pipe segments, respectively, the second pipe segment having a second pipe segment valve with an interior pressure area for exposure to interior pressure in an interior of the second pipe segment and an exterior pressure area for exposure to an exterior pressure on an exterior of the second pipe segment;
• operating the pump, creating a suction that results in the interior pressure acting on the interior pressure area that is less than the exterior pressure acting on the exterior pressure area, creating a negative pressure differential that urges the second pipe segment valve from a closed position toward the open position, and flowing well fluid into the base pipe along a first flow path through the first screen and the first set of perforations, and with the second pipe segment valve in the closed position, blocking well fluid flow through the second screen into the second set of perforations while the negative pressure differential is less than a selected level;
• then
• when the negative pressure differential reaches the selected level, applying a sufficient force on the second pipe segment valve with the negative pressure differential to move the second pipe segment valve to the open position and flowing well fluid along a second flow path through the second screen and into the second set of perforations.