Multi-mode pumped riser arrangement and methods
AssigneeEnhanced Drilling AS
InventorsPer Christian STENSHORNE, David Edward SMITH, Gustav Olov SKÄRGÅRD
Life of this patent
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Abstract
A riser system in the form of a pumped riser, i.e. a riser having an outlet from the riser at a depth below the surface of a body of water, where the outlet is coupled to a return pump to return fluid from the riser to the surface, and various operational methods to facilitate greater versatility when performing hydrocarbon drilling related operations. A sealing element to seal an annulus of the riser, and a by-pass around the sealing element. Various methods make it possible to switch between open mode and closed mode, and vice versa, monitoring leakage across the sealing element, as well as performing other operations exploiting the advantages of the two different modes.
Claims21
1-83. (canceled)
A method of measuring changes in liquid volume in a well having a riser extending from a bottom of a body of water the method comprising:
- providing a riser having a return outlet to be coupled to a return pump, the return pump being adapted to pump fluid from the riser to above a surface of the body of water through a return line;
- positioning a sealing element in the riser above the return outlet;
- providing a by-pass of the sealing element;
- operating in a closed mode where the sealing element and the by-pass are essentially closed to prevent flow therethrough;
- preparing to switch to an open mode by opening a branch line extending from a branch outlet in the riser above the sealing element to the return line from the return pump, thereby allowing liquid to flow from the return line into the riser;
- allowing the level of liquid in the return line to drop to a desired level;
- stopping the return pump;
- and
- determining changes in volume of liquid in the well based on measurement of volume in the return line.
A method of measuring changes in liquid volume in a well having a riser extending from a bottom of a body of water, the method comprising:
- providing a riser having a return outlet to be coupled to a return pump, the return pump being adapted to pump fluid from the riser to above a surface of the body of water;
- positioning a sealing element in the riser above the return outlet;
- providing a by-pass of the sealing element;
- operating in a closed mode where the sealing element and the by-pass are essentially closed to prevent flow therethrough;
- providing an auxiliary line extending from above the surface to an auxiliary line inlet on the riser below the sealing element;
- allowing liquid in the auxiliary line to flow into the riser;
- allowing the level of liquid in the auxiliary line to drop to a desired level;
- stopping the return pump;
- and
- determining changes in volume of liquid in the well based on measurement of pressure in the auxiliary line.
A method of determining volume changes in a well, extending from a bottom of a body of water, the method comprising:
- providing a riser having a return outlet to be coupled to a return pump, the return pump being adapted to pump fluid through a return line from the riser to above a surface of the body of water;
- positioning a sealing element in the riser above the return outlet;
- establishing a branch line from a branch line outlet in the riser above the sealing element to the return line;
- stopping or ramping down circulation of drilling fluid into the well;
- opening a by-pass of the sealing element;
- draining drilling fluid from the return line into the riser above the sealing element;
- and
- monitoring a level of drilling fluid in the return line.
A method of quantifying temperature-induced density changes of the mud in a well, based on measuring changes in liquid volume in a well extending from a bottom of a body of water comprising:
- stopping pumping liquid from a surface into the well;
- monitoring a level of drilling fluid in a riser extending from above a water surface and down to the well;
- determining level changes of drilling fluid in the riser;
- using known data on well geometry and well dimensions to calculate the volume of the well;
- providing known data about drilling fluid density as a function of temperature and pressure;
- using the known data about drilling fluid density and measured volume change in the riser to calculate temperature change and temperature-induced mud density reduction in the well;
- calculating a drop in downhole pressure caused by the temperature-induced drilling fluid density reduction;
- and
- calculating a change in drilling fluid density in the well related to temperature increase of the drilling fluid for determining a pressure at any point in the well.
Dependencies are inferred from the claim text.