An apparatus and method is provided for controlling and/or halting the uncontrolled flow of petroleum and/or natural gas from an open well head on the sea floor in which the well head is in communication with a subterranean formation. The method includes lowering a fluid control device from a drilling ship to an alignment means positioned above an open well casing through which the petroleum and/or natural gas is flowing in an uncontrolled manner, then lowering the fluid control device through and/or adjacent to the alignment means and into the open well casing until a lower section of a fluid control device enters the open well casing. The fluid control device includes an elongated member at its tip, having a diameter smaller than the inside diameter of the well head casing. A tapered section is in connection with the elongated section, the tapered section, or another section in connection with the tapered section, having a maximum diameter equal to or greater than the inside diameter of the well casing, and an end section in communication with the tapered section having a diameter greater than or equal to the outside diameter of the well head casing. The fluid control device can have a mass sufficiently great to overcome any upward forces created by flowing petroleum and/or natural gas, resulting in sufficient downward movement of the fluid control device and contact with the open well casing to seal same. Alternatively, a drilling rig in connection with the fluid control device can exert sufficient downward pressure thereon so as to overcome the pressure of the flowing petroleum, gas, etc., thereby creating a seal between the fluid control device and the well head.