Abstract: A flow rate regulating system within an oil well with casing with a diameter less than or equal to 3½ inches, wherein the flow rate regulating system comprises: at least one regulating valve, for regulating flowrate, having a generally cylindrical body with a plurality of elongated grooves, a top sub in its upper portion and a sliding sleeve inside; and a regulating and calibrating shifting tool for regulating and calibrating the position of the sliding sleeve which has a generally cylindrical collet, a block set and a pair of nuts on each side of the block set.