System and method for controlling the pressure of fluid in a subterranean void

A method for controlling a flow and an injection pressure of fluid to be injected into a subterranean void by a fluid handling system at an offshore injection site for long term storage, wherein the fluid handling system comprises a subsea template comprising a utility system with a valve system, wherein the subsea template is configured to receive fluid from a fluid storage and is arranged on a seabed in connection with at least two well heads for respective at least two drill holes to a subterranean void, wherein the subsea template is in fluid connection with each of the well heads of the at least two drill holes via a respective separate conduit or via a distribution manifold, wherein each drill hole has a top opening operatively connected to the well head and a bottom opening arranged to pass fluid into the subterranean void, the system further comprising a first pressure gauge for each drill hole, located at the bottom opening of the drill hole for measuring a bottom pressure, PB of the drill hole,

• wherein the method comprises, repeatedly:
• for each of the at least two drill holes:
• checking, by a control site, if a measured bottom pressure, PB, from the first pressure gauge has been received at the control site communicatively connected to the first pressure gauge and the subsea template;
• and
• if a measured bottom pressure, PB, has been received, setting, by the control site, the value of the measured bottom pressure, PB, as the current bottom pressure for the drill hole;
• and
• generating control commands (Ccmd), by the control site, configured to cause at least one choke valve of each drill hole to control the injection of the fluid into the subterranean void via the respective drill hole based on a respective pre-set desired flow rate for each drill hole and a pre-set lowest allowable flow rate from the fluid storage.

A non-transitory computer-readable storage medium storing instructions for a fluid handling system, the system comprising a subsea template including a utility system with a valve system, wherein the subsea template is configured to receive fluid from a fluid storage and is arranged on a seabed in connection with at least two well heads for respective at least two drill holes to a subterranean void, wherein the subsea template is in fluid connection with each of the well heads of the at least two drill holes via a respective separate conduit or via a distribution manifold, wherein each drill hole has a top opening operatively connected to the well head and a bottom opening arranged to pass fluid into the subterranean void, the system further comprising a first pressure gauge for each drill hole, located at the bottom opening of the drill hole for measuring a bottom pressure, PB of the drill hole, which instructions, when executed by processing circuitry of the fluid handling system, cause the system to, repeatedly:

• for each of the at least two drill holes:
• check if a measured bottom pressure, PB, from the first pressure gauge has been received at a control site communicatively connected to the first pressure gauge and the subsea template;
• and
• if a measured bottom pressure, PB, has been received, set the value of the measured bottom pressure, PB, as the current bottom pressure for the drill hole;
• and
• generate control commands (Ccmd), by the control site, configured to cause the at least one choke valve of each drill hole to control the injection of the fluid into the subterranean void based on a pre-set desired flow rate for each drill hole and a pre-set lowest allowable flow rate from the fluid storage.