Isolation device with multiple pressure stages to isolate well interval

A well interval isolation system comprising:

• a well interval isolation device positionable downhole in a wellbore and comprising:
• a first, uphole expandable element, and a second, downhole expandable element spaced apart on a tool string and cooperating with a primary interval tool to form a primary interval isolating section of the well interval isolation device;
• a third expandable element positioned on the tool string uphole of the first expandable element and cooperating with the first expandable element and a first uphole guard interval tool to form a first uphole guard interval section of the well interval isolation device;
• and
• a fourth expandable element positioned on the tool string downhole of the second expandable element and cooperating with the second expandable element and a first downhole guard interval tool to form a first downhole guard interval section of the well interval isolation device;
• wherein, the first expandable element and the second expandable element are expandable independently of the third expandable element and the fourth expandable element, and the primary interval tool is operable independently of the first uphole guard interval tool and the first downhole guard interval tool;
• and
• at least one pump in hydraulic communication with a fluid source and the expandable elements of the well interval isolation device, the at least one pump operable to expand the expandable elements by transmitting pressurized fluid to the expandable elements.

A method comprising:

• positioning a well interval isolation device at a target location within a wellbore, the well interval isolation device comprising:
• a first, uphole expandable element, and a second, downhole expandable element spaced apart on a tool string and cooperating with a primary interval tool to form a primary interval isolating section of the well interval isolation device;
• a third expandable element positioned on the tool string uphole of the first expandable element and cooperating with the first expandable element and a first uphole guard interval tool to form a first uphole guard interval section of the well interval isolation device;
• and
• a fourth expandable element positioned on the tool string downhole of the second expandable element and cooperating with the second expandable element and a first downhole guard interval tool to form a first downhole guard interval section of the well interval isolation device;
• expanding the first expandable element and the second expandable element independently of the third expandable element and the fourth expandable element to create, within the wellbore, a primary isolated well interval bounded on an uphole side thereof by a first uphole guard interval and bounded on a downhole side thereof by a first downhole guard interval;
• operating the first uphole guard interval tool and the first downhole guard interval tool to respectively pressurize or depressurize the first uphole guard interval and the first downhole guard interval to a desired pressure level;
• and
• independently operating the primary interval tool to correspondingly pressurize or depressurize the primary isolated well interval to a pressure level that exceeds the pressure level of the first uphole guard interval and the first downhole guard interval.