Wells – Processes – Separating material entering well
Reexamination Certificate
1998-03-18
2001-04-10
Will, Thomas B. (Department: 3673)
Wells
Processes
Separating material entering well
C166S105100, C166S369000, C210S512200, C210S170050
Reexamination Certificate
active
06213208
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of separating production fluid from an oil well.
2. Description of the Related Art
Increasingly, oil producers are looking for ways to produce oil from wells in which the production fluid has a high water cut efficient enough to make the cost of the production economic. One way of achieving this is shown in U.S. Pat. No. 4,738,779, which discloses the use of a liquid/liquid hydrocyclone within a well bore in order to provide initial separation of some of the water from the production fluid to reduce the quantity of production fluid which needs to be transported to the surface. The separated water is returned to the oil reservoir, or to another reservoir which has been exhausted.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a method of separating oil well production fluid containing oil, water and sand comprises transporting the production fluid to a downhole liquid/liquid hydrocyclone, separating the production fluid in the liquid/liquid hydrocyclone into an oil enriched stream at the hydrocyclone overflow and a water enriched stream at the hydrocyclone underflow, transporting the oil enriched stream to the surface, transporting the water enriched stream to a downhole solid/liquid hydrocyclone, separating the water enriched stream in the solid/liquid hydrocyclone into a solid depleted stream at the overflow and a solid enriched stream at the underflow, and transporting the solid depleted stream to a downhole disposal site.
By providing a solid/liquid hydrocyclone in this way, the method of the present invention ensures that the solid depleted stream which is fed to the disposal site is generally free of solids. This avoids a problem of the prior art, namely the blocking of pores in the rock at the disposal site, which hinders the reinjection of the separated water. Also, in the prior art, in high solids producing wells, the wellbore itself can become blocked below the level of the hydrocyclones.
To some extent, the pressure of the production fluid can be used to drive the two hydrocyclones. However, additional pumps are generally necessary, for example, to pump the production fluid in the line feeding the liquid/liquid hydrocyclone, or to pump the oil enriched stream being transported to the surface.
The solid enriched stream may be disposed of in a suitable underground site. However, preferably, the solid enriched stream is transported to the surface for disposal and/or further treatment. The oil enriched stream and the solid enriched stream may be transported separately to the surface. However, the two streams can be combined to be transported jointly to the surface.
This arrangement forms further aspects of the present invention which can be defined as an apparatus for separating a mixture containing oil, water and sand, the apparatus comprising a liquid/liquid hydrocyclone for separating the mixture into an oil enriched stream at the hydrocyclone overflow and a water enriched stream at the hydrocyclone underflow; a first duct leading from the hydrocyclone overflow for the transport of the oil enriched stream; a second duct leading from the hydrocyclone underflow for the transport of the water enriched stream; a solid/liquid hydrocyclone, fed with the water enriched stream in the second duct, for separating the water enriched stream into a solid depleted stream at the overflow and a solid enriched stream at the underflow; and a third duct leading from the solid/liquid hydrocyclone underflow and joining with the first duct, so that the oil enriched stream and the solid enriched stream are transported together downstream of the joint between the first and third ducts.
The disposal site for the solid depleted stream may be an adjacent reservoir which has been exhausted. Preferably, however, the method of the present invention further comprises drilling two bores from one surface well into the same production formation and installing the hydrocyclones into the well so that the production fluid to be treated is taken from a first bore and the solid depleted stream is returned via the second bore to the formation at a location below that at which the production fluid is removed. This ensures that the bulk of the fluids removed from the formation is returned, so that the formation pressure is maintained and dissolved gas remains in solution. Also, the residual oil in the formation is “swept” towards the first bore.
REFERENCES:
patent: 3737037 (1973-06-01), Bone, III
patent: 3764008 (1973-10-01), Darley et al.
patent: 3860019 (1975-01-01), Teague
patent: 4453960 (1984-06-01), Andrepont
patent: 4793408 (1988-12-01), Miffre
patent: 4960525 (1990-10-01), Dalby et al.
patent: 5296153 (1994-03-01), Peachey
patent: 5344255 (1994-09-01), Toor
patent: 5350525 (1994-09-01), Shaw et al.
patent: 5456837 (1995-10-01), Peachey
patent: 5693225 (1997-12-01), Lee
patent: 5730871 (1998-03-01), Kennedy et al.
patent: 5762149 (1998-06-01), Donovan et al.
patent: 5788464 (1998-08-01), Gabelgaard
patent: 5860476 (1999-01-01), Kjos
patent: 5879541 (1999-03-01), Parkinson
patent: 5996690 (1999-12-01), Shaw et al.
patent: 6017456 (2000-01-01), Kennedy et al.
patent: 6033567 (2000-03-01), Lee et al.
patent: WO 94 139030 (1994-06-01), None
Kjos, T., et al., “Subsea and DownHole Separation Systems- The Latest advances” Paper XP000671682 READ Process Engineering Norwegian Institute of Technology 1996.*
Offshore (Inc. The Oilman), vol. 55, No. 6, Jun. 1, 1995, p. 16 XP000512449, “Downhold Separator Uses Hydrocyclone, Zone Discharge.”
Baker Hughes Limited
Kreck John
Trask & Britt
Will Thomas B.
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