Underbalance jet pump drilling method
AssigneeUnion Oil Company of California
InventorsMark D. Mueller, William O. Jacobson
Life of this patent
Estimating the term…
Abstract
A method for rotary drilling and removing cuttings provides a underbalanced drilling fluid pressure at the drilling face but overbalanced pressure in the wellbore. The preferred method uses a rotary drill within a housing which also encloses a jet pump which draws and pressurizes the cuttings and drilling fluid, a separator of the cuttings and a portion of the pressurized drilling fluid, and a nozzles to supply separated and reduced pressure drilling fluid back to drilling face while the cuttings and remaining pressurized drilling fluid flows up towards the surface. The method avoids overpressure strengthening of the drill face and underpressure damage to the wellbore.
Claims22
A drilling apparatus for drilling an underground wellbore from a surface location which comprises:
- a rotary drill capable of producing cuttings from an underground formation face;
- a housing partially enclosing said rotary drill, said housing capable of restricting fluid flow between an upper portion and a lower portion when said rotary drill is drilling;
- jet pump means located proximate to said housing and capable of inducing a mixture comprising a drilling fluid and said cuttings at a first pressure from said lower portion and discharging said mixture at a second pressure to said upper portion when said jet pump means is actuated by a power fluid and said rotary drill is rotated, wherein said jet pump directs said mixture in a direction not toward said underground formation face when said drill is producing said cuttings;
- and
- a source of a power fluid stream attached to said jet pump means.
A drilling apparatus for drilling an underground wellbore from a surface location which comprises:
- a rotary drill capable of producing cuttings from an underground formation face;
- a housing partially enclosing said rotary drill, said housing capable of restricting fluid flow between an upper portion and a lower portion when said rotary drill is drilling;
- jet pump means located proximate to said housing and capable of inducing a mixture comprising a drilling fluid and said cuttings at a first pressure from said lower portion and discharging said mixture at a second pressure to said upper portion when said jet pump means is actuated by power fluid and said rotary drill is rotated;
- a source of a power fluid stream attached to said jet pump means;
- and
- a partial separator for separating a majority of said cuttings from said power fluid after said power fluid stream actuates said jet pump, said partial separator located proximate to said housing.
A drilling apparatus which comprises:
- a drill capable of producing cuttings from an underground formation face in a cavity;
- a housing attached to said drill, said housing capable of restricting fluid flow between a first portion of said cavity and a second portion of said cavity proximate to said formation face;
- fluid pump means for removing said cuttings and a fluid mixture from said second portion at a first pressure and discharging said cuttings and said fluid mixture to said first portion at a second pressure which is greater than said first pressure, wherein said fluid pump means directs said mixture in a direction not towards said underground formation face when said drill is producing said cuttings;
- and
- a source of a power attached to said pump means.
A process for drilling an underground borehole from a location near a surface using a rotary drill at a formation face with a drilling fluid to produce cuttings at a formation face, said process comprising:
- supplying a jet portion of a pressurized power fluid to a jet pump drawing on said drilling fluid and cuttings at an underbalanced pressure, pressurizing said cuttings and said drilling fluid to form a pressurized mixture at an overbalance pressure;
- discharging a first portion of said pressurized mixture towards said surface;
- supplying a drilling portion of said power fluid to a location proximate to said formation face when said location is at said underbalanced pressure;
- and
- downhole separating at least a portion of said pressurized drilling fluid and said power fluid from said cuttings to form said drilling portion.
A process for drilling a wellbore which comprises:
- producing cuttings from a solid material;
- pumping said cuttings entrained in entraining fluid located proximate to said material, forming a pumped mixture, said pumping being motivated by a power fluid stream;
- separating at least a portion of said entraining fluid from said cuttings within said wellbore;
- and
- diverting a portion of said power fluid stream to a location proximate to said drill, forming at least part of said entraining fluid.
Dependencies are inferred from the claim text.