Patent ID: 8261822

Claim:
A method of injecting fluid into a well comprising: (a) isolating first and second formations in a well from one another; (b) providing flow valves comprising: a body, a bore substantially coaxial formed through the body to define an inlet at an end of the body and an exit at an end of the body distal from the inlet. a fixed sleeve in the body having an annular chamber with an open end in fluid communication with the inlet, a sidewall, and a opening that extends radially outward through the sidewall, a sliding sleeve coaxially disposed in the bore having an annular sidewall that coaxially slides over an outer surface of the fixed sleeve, a first opening in the annular sidewall and a second opening in the annular sidewall spaced axially apart from the first opening, wherein the first opening is selectively registerable with the opening in the fixed sleeve, and an orifice in an end of the sliding sleeve distal from the first opening, and a spring biasing the sliding sleeve towards the inlet in the body, (c) extending conduit from a wellhead assembly into the well, the conduit having a first port in fluid communication with the first formation and a second port in fluid communication the second formation and providing a flow valve on each of the first port and second port; and (d) pumping fluid down the conduit and to the ports, so that when the fluid enters the inlets in the flow valves, flows to an annulus circumscribing the sliding sleeve, flows radially inward through the second openings, flows through the orifice and to the outlet in the body when the first openings are in registration with the openings in the fixed sleeve, and so that when the fluid generates a pressure drop through the orifice, the sliding sleeve is moved to reduce an amount of flow through the first openings thereby controlling flow through each of the ports so that the flow rates through each of the ports is substantially constant as the pressure difference between the conduit and the first and second formations vary.