WELL UPLIFT SYSTEM

Abstract: A method of raising material, such as production fluid (6), from a bore hole (3) involves pumping water down a pipe (7) to a fluidising unit (A) so that the water activates and entrains the material and carries it up through a discharge conduit (8) to a separator (B).

Description: WELL VPLTFT SYSTEM Conventionally, production fluids, such as oil, are lifted out of a predrilled or naturally formed well hole in the ground, by the pressure under which an underground reservoir of the product is maintained, either naturally or artificially by injection in the neighbourhood of the reservoir of fluid such as water. Alternatively they are recovered by lowering a pump into the well hole at the lower end of a discharge conduit. If the product reservoir is no. under a naturally occurring pressure, and the local pressure is raised by injection of, for example, water, the system is inefficient in that the applied pressure is dispersed throughout the ground and is not effective to direct the product up the well hole. Downhole pumps are also inefficient in that they necessarily transfer with the product spoil, in the form of particulate solids, which abrade, and at worst block, the pump. Production fluids are usually two phase, and include liquid and gas in varying proportions. Pumps have difficulty in handling such mixtures. Mechanical pumping also tends to shear liquid oil and to form, with the water present, an emulsion ¥hich akes a long time to separate again. Downhole pumps are al~o expensive and have high maintenance costs as a esult of the inaccessibility of their moving parts. In accordance with the present invention, a method of raising production fluid or material from a bore hole in the ground comprises pumping water down a first conduit in the bore hole into contact with the material whereby the material is entrained and carried up through a second conduit in the bore hole to a separator where at least partial separation of the water and material takes place. By means of this method production fluids can readily be recovered from down a well, particularly as oil and gas will tend to rise in the water, quite apart from being entrained by it. Slugs of gas in the production fluid can be accommodated without difficulty. Emulsification of the oil with water is minimal so that preliminary separation of the oil, gas and water at the surface can be conducted comparatively simply with a short residence time in, for example, a settling tank or cyclone system. Although the method may not be quite as efficient in transferring the production fluids, as the downhole pump, the previously mentions problems of using pumps downhole are avoided and the trade off is considered to be beneficial. The water may be taken at source, ie may be deaerated aquafier water thereby avoiding compatibility problems. It is believed that, in a typical case, adequate water could be pumped down the borehole by means of a centrifugal pump providing a pressure of the order of 2500 psig. Complete separation of the water from the oil and gas is unnecessary as the water which has been at least partially separated may be arranged to pass around a closed loop and pumped down the first conduit again. This also minimises compatibility problems. Although the method is seen as being of particular value in recovering production fluids from an oil-well, it is believed to have other applications, for example in recovering material such as drill cuttings from the bottom of a drill pipe which is used to cut the bore hole. The material is preferably entrained by the use of a fluidising unit located downhole, and to and from which the first and second conduits respectively lead, the fluidising unit being of a kind having a supply duct which is connected to the first conduit and a discharge duct which is connected to the second conduit and which is located within the supply duct, the end of the discharge duct extending beyond the end of the supply duct. Such a unit operates in that water injected out through the supply duct activates the material which is consequently driven centrally up through the discharge duct, entrained in the fluid, and hence to the surface. The fluidising effect is enhanced if the water is arranged to swirl as it leaves the supply duct, for example as a result of the first conduit leading tangentially into the supply duct, or by means of helical vanes within the supply duct. A fluidising unit which operates on this principal is disclosed in our US-A- 4978251. The invention also includes a system for raising material from a bore hole in the ground, the system comprising a fluidising unit which is arranged to be located downhole and which includes a supply duct having an outlet at its end and being connected to a first conduit which extends from a pump down through the bore hole to supply fluid under pressure to the supply duct, and, within the supply duct, a discharge duct, which has at its end an inlet located beyond the fluid supply duct outlet, the discharge duct being connected to a second conduit which extends up through the bore hole to a separator for at least partially separating the fluid and the material. An example of an oil-well and associated plant, constructed in accordance with the present invention, is illustrated diagrammatically in the accompanying drawings, in which: Figure 1 is a diagram showing the essential parts; and, Figure 2 is a longitudinal section through a fluidising unit. As shown in Figure 1, a well 3 has been bored down into the ground 4, and may have a casing 5. Production fluid 6 collects in the bottom of the well. Extending down the well, within an appropriate tool string, are a supply pipe 7 and a discharge pipe 8, both of which are connected at the bottom t a fluidising unit A. This is shown in section in Figure 2. The unit has a cylindrical housing 9 through which there extends the lower end of the pipe 8. The pipe 7 leads into a manifold 10 which surrounds the top of the housing 9 and has a tangential inlet 11 into the annular space between the pipe 8 and housing 9, that space forming a supply duct SD. The lower end of the pipe 8 forms a discharge duct DD and terminates in a flared portion 12. The annular space between the pipe 8 and housing 9 may be provided with vanes in addition, o instead of the inlet 11 being tangential, in order to caus water discharged down through the supply duct to swirl. In use, with a packer 13 isolating the space below th unit A, deaerated water is pumped by a pump PI at th mudline, rig or surface, from a storage container G dow the pipe 7 and through the supply duct SD to activate an entrain the production fluid 6, which is then carried u the discharge duct DD and pipe 8 to a settling chamber B In this oil, gas and water, and any solids present, wil separate into respective layers. A device C separates bul water from the phases from the well with the bulk wate phase being diverted to a device E in which smal quantities of oil are removed from the water so that it ca be degassed and deoiled further in a device F prior t being either dumped to waste via a valve VI or recycled vi a pump P2 to the storage vessel G via a line 14. Th device C also allows the gas to be separated from th fluids, and for solids to settle out, the 01 phase passin to a second stage D which further treats the fluids i required to achieve export quality crude oil. Chemical can be injected into any of the devices to enhance th efficiency of the system.

Claims: CLAIMS 1. A method of raising production fluid or other material from a bore hole (3) in the ground, the method comprising pumping water down a first conduit (7) in the bore hole into contact with the material whereby the material is entrained and carried up through a second conduit (8) in the bore hole to a separator (B) where at least partial separation of the water and material takes place. 2. A method according to claim 1, in which the water which has been at least partially separated from the material passes around a closed loop (14,G) and is pumped down the first conduit (7) again. 3. A method according to claim 1 or claim 2, in which the first and second conduits (7,8) lead respectively to and from a fluidising unit (A) located downhole and of a kind having a supply duct (SD) which is connected to the first conduit and a discharge duct (DD) which is connected to the second conduit and which is located within the supply duct (SD) , the end of the discharge duct (DD) extending beyond the end of the supply duct. 4. A method according to claim 3, in which the water is arranged to swirl as it leaves the supply duct (SD) . 5. A system for raising material from a bore hole in the ground, the system comprising a fluidising unit (A) which is arranged to be located downhole and which includes a supply duct (SD) having an outlet at its end and being connected to a first conduit (7) which extends from a pump (PI) down through the bore hole to supply fluid under pressure to the supply duct, and, within the supply duct, a discharge duct (DD) , which has at its end an inlet located beyond the fluid supply duct outlet, the discharge duct being connected to a second conduit (8) which extends up through the bore hole to a separator (B) for at least partially separating the fluid and the material. 6. A system according to claim 5, in which the supply duct (SD) is provided with means (11) for causing the fluid to leave the supply duct outlet with a swirling motion. 7. A system according to claim 5 or claim 6, in which there is a closed loop (14,G) interconnecting an outlet from the separator for the separated fluid and an inlet of the pump. AMENDED CLAIMS [received by the International Bureau on 23 August 1993 (23.08.93); original claims 1 and 3 replaced by amended claim 1; claims 4 - 7 amended and renumbered as claims 3 - 6 other claims unchanged (2 pa 1. A method of raising production fluid from a well (3) in the ground, the method comprising pumping water down a 5 first conduit (7) in the well into contact with the material whereby the material is entrained and carried up through a second conduit (8) in the well to a separator (B) where at least partial separation of the water and fluid takes place; characterised in that the first and second 10 conduits (7,8) lead respectively to and from a fluidising unit (A) located downhole and of a kind having a supply duct (SD) which is connected to the first conduit and a discharge duct (DD) which is connected to the second conduit and which is located within the supply duct (SD) , 15 the end of the discharge duct (DD) extending beyond the end of the supply duct. 2. A method according to claim 1, in which the water which has been at least partially separated from the 20 material passes around a closed loop (14,G) and is pumped down the first conduit (7) again. 3. A method according to claim 1 or claim 2, in which the water is arranged to swirl as it leaves the supply duct 25 (SD) . 4. A system for raising production fluid from a well in the ground, the system comprising a fluidising unit (A) which is arranged to be located downhole and which includes 30 a supply duct (SD) having an outlet at its end and being connected to a first conduit (7) which extends from a pump (PI) down through the well to supply fluid under pressure to the supply duct, and, within the supply duct, a discharge duct (DD) , which has at its end an inlet located 35 beyond the fluid supply duct outlet, the discharge duct being connected to a second conduit (8) which extends up through the well to a separator (B) for at least partially separating the fluid and the material. 5. A system according to claim 4, in which the supply duct (SD) is provided with means (11) for causing the fluid to leave the supply duct outlet with a swirling motion. 6. A system according to claim 4 or claim 5, in which there is a closed loop (14,G) interconnecting an outlet from the separator for the separated fluid and an inlet of the pump. STATEMENT UNDER ARTICLE19 Old claims 1 and 3 have been combined. Old claims 4 to 7 have been renumbered and their dependencies have been amended accordingly. The introduction will be amended during the international preliminary examination for consistency with amended claim 1. Claim 1 has been amended in order to distinguish from the art cited in the international search report. It is submitted that this claim is not an obvious combination of US-A-4603735 and FR-A-2633263. The present invention relates to removing production fluids such as oil and gas from a bore hole in the ground. FR-A-2633263 relates only to an apparatus for fluidising a bed of solid particles to produce a slurry. There is nothing in this citation to suggest that the apparatus is applicable to the transportation of fluids. There is therefore no reason why a person skilled in the art would consider using this apparatus in a bore hole to remove production fluid as there is no indication that it would be practical in such circumstances. To clarify the distinction over this citation, the claims have been amended to refer to "raising production fluid from a well", instead of "raising production fluid or other material from a bore hole". The invention offers a considerable improvement over the apparatus of US-A-4603735. The jet pump of this citation will work at high velocity and will therefore tend to shear liquid oil to form with the water present an emulsion containing very fine droplets of oil which are difficult to separate from the water after pumping up to the surface. The present invention allows the production fluid to be removed from the bore hole much more gently without causing oil droplet breakup. This allows much easier separation at the surface.

Inventors: ADAMS JOHN EDWARD, SMITH ROBERT MELVILLE, ADAMS, JOHN, EDWARD, SMITH, ROBERT, MELVILLE
Applicants: MERPRO TORTEK LTD, MERPRO TORTEK LIMITED
Application year: 1993
Main classification: E21B43
IPC codes: E21B43