Apparatus and methods for limiting debris flow back into an underground base pipe of an injection well

An isolation flow assembly removably engageable with a base pipe of an underground fluid injection system, the base pipe being positionable within or adjacent to an underground earthen formation and having at least one fluid flow opening through which fluid may be injected from the base pipe into the earthen formation, the isolation flow assembly being capable of varying at least one flow characteristic of fluid injected into the earthen formation from the base pipe, the isolation flow assembly comprising:

• an isolation member axially moveable within the base pipe, said isolation member having at least one fluid flow passage, said at least one fluid flow passage having at least one dimension that differs from the dimensions of the at least one fluid flow opening of the base pipe, said at least one fluid flow passage being in fluid communication with at least one fluid flow opening of the base pipe when the isolation flow assembly is engaged with the base pipe;
• and
• a releasable locking assembly connected with said isolation member and axially moveable within and releasably engageable with the base pipe,
• whereby at least one flow characteristic of fluid injected into the earthen formation from the base pipe may be varied by moving said isolation member and said releasable locking assembly into the base pipe and either engaging said releasable locking assembly with the base pipe or disengaging said releasable locking assembly from the base pipe and removing said isolation member and said releasable locking assembly from the base pipe.