Electric resistance heating devices – Heating devices – Borehole type
Reexamination Certificate
2000-03-17
2001-03-20
Jeffrey, John A. (Department: 3742)
Electric resistance heating devices
Heating devices
Borehole type
C166S302000, C166S057000, C166S052000
Reexamination Certificate
active
06205289
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved method and system for production of steam for steam injection in oil wells.
Many oil reservoirs contain heavy oil having a viscosity that makes it economically difficult or impossible to produce oil using conventional methods. Large oil reservoirs of this type are located in e.g. Venezuela
The most common methods for recovering heavy, high viscosity oils comprises injection of steam into the reservoir. Steam enhances the production of heavy oil by reducing the viscosity by heating.
According to one method referred to as cyclic steam stimulation (CSS), steam is injected into a well for a period of several days to a few months. The well is then shut down for a period known as the soak period, before well is brought on production for a period. After this production period the same cycle is repeated.
According to another method known as steam drive, steam is injected into some wells dedicated to continuous steam injection at the same time as oil is produced in adjacent wells.
Today, steam for injection into wells is produced by means of gas fired boilers in a centralised unit on the field. The steam, having a temperature of approx. 300° C. and a pressure of about 100 bar, is transported from this unit to the wells by means of high pressure pipelines.
As an example, the area of an oil field may be 600 square km, and may have 40 or more clusters of wells, each cluster typically having approx. 10-50 wells. The investment costs in pipelines and steam generators are therefore substantial. The thermal loss in the pipelines is large.
SUMMARY OF THE INVENTION
The main objective of the invention is to obtain a system for decentralised generation of steam for injection into a plurality of well bores in an oil field to improve the recovery of crude oil from the oil field.
This objective is met by a system for generation of steam for injection into a plurality of well bores in an oil field to improve the oil recovery from the oil field, wherein the system comprises a plurality of electric powered steam-generating units, each unit delivering steam for injection into a one well bore or number of geographically close well bores.
Preferably, each steam-generating unit comprises an electric boiler supplied receiving electric power from an electric power distribution net.
Each steam-generation unit preferably comprises equipment for remote control.
It is preferred that each steam-generation unit also comprises a de-aerator.
Most preferably, each steam-generating unit is mounted on a separate transportable frame or skid for transport from one well bore to another.
Another object is to provide a steam-generating unit for generation of steam for injection into a well bore in an oil field to improve the oil recovery from the oil field.
This object is met by a steam-generating unit for generation of steam for injection into a well bore in an oil field to improve the oil recovery from the oil field, wherein said steam-generating unit comprises an electric boiler and additional equipment mounted on a transportable skid or frame for transport from one well bore to another.
It is preferred that each steam-generating unit also comprises equipment for remote control.
It is also preferred that each steam-generating unit comprises a de-aerator.
The invention also includes a use of a plurality of electric powered steam-generating units for generation of steam for injection into a plurality of well bores in an oil field to improve the oil recovery from the oil field, wherein each steam-generating unit delivers steam for injection into one well bore or a number of geographically close well bores.
REFERENCES:
patent: 4262745 (1981-04-01), Stewart
patent: 4322603 (1982-03-01), Bright
patent: 4408665 (1983-10-01), Dougan
patent: 5715895 (1998-02-01), Champness et al.
Den Norske Stats Oljeselskap A.S.
Jeffrey John A.
Quarles & Brady LLP
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