Liquid lift method for drilling risers
AssigneeExxonMobil Upstream Research Company
InventorsCharles Rapier Dawson, Yuh-Hwang Tsao, Sandra Nowland Hopko
Life of this patent
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Abstract
A method for drilling a well below a body of water as disclosed which includes injecting into the well, at a depth below the water surface, a liquid having a lower density than a density of a drilling mud producing a mixture of drilling mud and low-density liquid in the well. The mixture of drilling mud and low-density liquid is withdrawn from an upper end of the well. The drilling mud and the low-density liquid are separated, with at least a portion of the separated low-density liquid returned to the depth below the water surface and at least a portion of the separated drilling mud returned to an upper end of the drill string.
Claims20
A method of drilling a well below a body of sea water in which a drill bit is rotated at the end of a drill string, comprising:
- (a) injecting into the well at a depth below the water surface a liquid having a lower density than a density of a drilling mud producing a mixture of drilling mud and low-density liquid in the well;
- (b) withdrawing the mixture of drilling mud and low-density liquid from the well wherein the mixture has a density greater than the sea water at the seafloor surrounding the well;
- (c) separating at least a portion of low-density liquid from the mixture of drilling mud and low-density liquid, thereby producing a drilling mud depleted of low-density liquid;
- (d) returning at least a portion of the separated low-density liquid to the depth below the water surface;
- and
- (e) returning at least a portion of the drilling mud depleted of low-density liquid to an upper end of the drill string.
A method of treating a drilling fluid used in drilling a wellbore in a earth formation below a body of water in which a drill string extends from a water-surface drilling facility into the wellbore and the drilling fluid passes through the drill string and flows from the drill string into the wellbore whereby cuttings resulting from the drilling becomes entrained in the drilling fluid and the drilling fluid with the entrained cuttings returns to the surface of the body of water by means of a return flow system, comprising
- (a) injecting into the return flow system at a depth below the surface of the body of water a liquid having a density lower than a density of the drilling fluid, thereby producing in a return flow system a mixture of drilling fluid and a low-density liquid;
- (b) withdrawing the mixture of drilling fluid and low-density liquid from an upper end of the return flow system wherein the mixture has a density greater than the seawater at the seafloor surrounding the well;
- (c) separating at least a portion of the low-density liquid from the mixture of drilling fluid and low-density liquid, thereby producing a drilling fluid depleted of low-density liquid;
- (d) returning at least a portion of the separated low-density liquid to the return flow system to the depth below the water surface;
- and
- (e) returning at least a portion of the drilling fluid depleted of low-density liquid to the drill string.
Dependencies are inferred from the claim text.