Patent Application
20120205098
The present invention relates to equipment feeding polymers into a fluid flow, in particular into floodwaters used in petroleum extractions as claimed in the preamble of claim 1.
Frequently petroleum is extracted from the pores of stratified rocks. It will be highly pressurized therein. When such a reservoir is discovered by drilling, the oil initially bubbles up the well bore due to its prevailing excess pressure until latter is counterbalanced. When the site pressure drops, the extraction oil is then additionally pressurized using engineering accessories, in general sub-surface pumps. These procedures are called primary production.
When subsequently oil production drops further, additional drilling will be carried out at other sites. Flooding water is forced by injection probes through such additional holes to raise the reservoir pressurization and to force the oil toward the production well. This production phase is called secondary production.
A problem arises during secondary production in that a large portion of the flooding water pumped into the oil reservoir seeps either into porous zones, cracks or ducts of the rock formation, or the rapidly moving water moves through the less mobile oil. This phenomenon is called “fingering”. A “water cone” forms around the production well, as a result of which only water now enters the production well, the oil remaining in the reservoir.
To meet such problems, new technologies were developed generically called “Tertiary production” or “Enhanced Oil Recovery (EOR)”. Illustrative known procedures apply steam, nitrogen or carbon dioxide or polymer flooding, the latter being fairly widespread. In polymer flooding, high molecular-weight polymers area admixed to the flooding water(s) to raise the water's viscosity until its mobility inside the reservoir approximately matches that of the oil. “Fingering” is eliminated and petroleum extraction may be enhanced further. Widely used polymers illustratively are polyacrylamides, methacrylamides or partly hydrolyzed polyacrylamides.
Polymer flooding incurs the drawback that the pertinent polymers are relatively susceptible and their molecules are rapidly destroyed by dissociation, usually entailing drastic loss of the flooding water's viscosity. Polymer dissociation moreover may be due to chemical processes, for instance in the presence of salts, or by hydrolysis. On the other hand mechanical loads (denoted herein as “stresses” due to compressive, tensile, shearing forces and the like also are important, the relatively large molecules being exposed to strong turbulence in valves, pipe bends, narrow sites and injection nozzles and hence to high shearing forces, resulting in damage to the molecular structure, in particular to the polymer's backbone. Consequently the polymers are already destroyed when metering and admixing the polymer solution to the flooding water. The flooding water's viscosity is lowered, whereby its is adversely affected relative to the petroleum to be extracted. Such a state does affect polymer flooding and renders its economical value questionable.
The objective of the present invention is to eliminate the above and further drawbacks of the state of the art and to create equipment feeding polymers into a fluid flow, this equipment allowing manufacture by simple means and offering easy handling. This equipment makes it feasible to feed polymers—especially polymers of high molecular weights and in aqueous solution—at a predetermined pressure and at a defined rate (quantity per unit time) into a fluid flow without destroying the polymers' molecular chains.
Claim 1 of the present invention discloses its main features. Claims 2 through 12 disclose various embodiment modes.
The solution of the present invention is equipment feeding polymers through a pipeline into a to fluid flow, comprising a control connectable to a polymer supply line, further several feed conduits feeding the polymers from the control to the pipeline, the control being fitted with a valve system designed in a manner that a defined number of feed conduits may be opened or closed, at least one static mixer being configured at least segment-wise in each feed conduit.
This equipment makes it possible in surprisingly simple manner to feed polymers into a fluid flow in particular with respect to flooding water used in petroleum extraction, without thereby damaging their molecular structures, said water being applied through a pipeline to a petroleum reservoir. The invention allows doing so because the polymers typically fed in aqueous solution to the control are not required to flow through a single valve aperture, but instead are distributed by means of said control and its valve system through a plurality of feed conduits configured between said control and the fluid flow pipeline. In a defined number and depending on the open or closed positions of the valve system, the individual feed conduits shall be consecutively and/or at least partly opened respectively closed, as a result of which the rate of polymer solution passing through the feed conduits into the fluid flow's pipeline can be accurately regulated and precisely metered. As a result the polymers meet with substantially reduced turbulences and shear forces within the individual feed conduits and thereby cannot be destroyed by those they do encounter.
The static mixers configured within the individual feed conduits are pressure reducers and lower in controlled manner the pressure at which the polymers enter the fluid flow's pipeline without however mechanically stressing the polymers or even damaging them. In this manner too the shear forces are significantly reduced in the equipment. The usually very long and heavy polymer molecular chains are preserved almost entirely, not being destroyed by shearing stresses or other mechanical forces.
By means of the equipment of the present invention, the viscosity and hence the mobility of the flooding water can always be adjusted/set optimally to the particular requirements of each oil well of production needs without incurring a drop in viscosity when admixing the polymers to the flooding water. The equipment of the invention comprising few moving parts, it is highly compact and rugged, and its manufacture is economical.
To further allow accurately and individually controlling the pressure at which the polymers are fed into the pipeline, the present invention furthermore provides that the static mixers within the feed conduits be of different lengths. Also the number and/or the configuration of the mixing elements may vary between the individual static mixers in the feed conduits and/or within a static mixer. In this manner the desired drop in pressure and the intensity of mixing within the polymer solution can be accurately predetermined. Nevertheless no mechanical stresses are incurred within the polymers. All of the polymer solution enters the fluid flow as a uniform laminar stream, and thereby the long molecular chains are preserved fully. The flooding water's viscosity may be adjusted precisely.
In another embodiment mode of the equipment of the invention, the diameters of the feed conduits are different. This feature also contributes to accurate polymer metering.
The equipment of the present invention offers a further substantial advantage in that the admixture of polymers to the fluid flow may be automated, illustratively using the control, when, depending on the desired flooding water viscosity to be or already having been attained, feed conduits of defined diameters and fitted with static mixers and given configurations shall be opened and/or closed in controlled manner. Illustratively several feed conduits of different diameters and fitted with different mixers may be opened to attain a controlled feed of a given polymer solution resulting in a given viscosity of the fluid flow. However several feed conduits of the same diameters and fitted with identical static mixers may be simultaneously opened and then closed again. Preferably an electric or electronic switching device is used to drive the control. Additionally, the reliability of operation is very high, since failure in one of the feed conduits might be remedied by using another.
Depending on the installation status of the equipment of the invention or the local conditions, each feed conduit may be made to issue into a feed lance in turn terminating into the pipeline. As a result the feed lance can be connected by a single flanged lock to the pipeline.
In another embodiment mode of the invention, each feed conduit issues directly into the pipeline. As a result, the solution of polymer(s) need not be combined within a feed lance; the laminar flow inside the feed conduits is preserved entirely, further lowering the mechanical stresses of the polymers in the polymer solution.
To assure appropriately distributing the polymer solution of the pipeline into the fluid flow, each feed conduit must enter to different depths said pipeline. The polymers are uniformly distributed cross-sectionally in this fashion.
In a further, significant embodiment mode of the present invention, the valve system comprises an adjustment cylinder fitted with control apertures to open up the feed conduits, each such control aperture being associated with one feed conduit. This design also allows automating opening and closing the feed conduits as needed, the adjustment cylinder being appropriately fitted with a mechanical, electrical, pneumatic or hydraulic drive itself powered by an electric or electronic control.
Just as do the feed conduits, the control apertures may be sized differently, preferably being oblong holes. As a result and depending on the configuration and orientation of said oblong holes on the adjustment cylinder, the feed conduits may be driven to open consecutively or in a given sequence, however they may also be opened and closed in partly parallel manner. Accordingly the invention makes it feasible—by setting in defined manner the adjustment cylinder within the control—to switch open in controlled manner given feed conduits having specified diameters and fitted with specified static mixers, as a result of which an accurately quantity of polymer solution is moved through these selected conduits at an accurately defined pressure and in laminar flow to the flooding water, and this in the absence of mechanical stresses on the polymers, within the said equipment.
Advantageously as regards manufacturing, the adjustment means is operable along the control's longitudinal axis, for instance using a linear drive.
Preferably however, the adjustment cylinder is supported to be rotatable about control's longitudinal axis, for instance using a rotary drive, thereby allowing advantageous equipment size reduction. Simultaneous in this feature, the mechanical stresses applied to the polymers are further reduced within the valve system. The adjustment cylinder no longer carrying out strokes but instead pure swiveling, the change of the feed conduits' control cross-sections now is implemented by a tangential displacement. As a result said feed conduits may be individually opened and closed entirely as needed. Moreover the swivel piston reduces the size of the control because the adjustment cylinder no longer need being linearly extended.
Further features, detail and advantages of the present invention are disclosed in the claims and the description of the following illustrative embodiment modes in relation the appended drawings.
The equipment, denoted as a whole by 10 in the drawings, feeds polymers into a fluid flow and is designed to service an oil field, in particular in secondary or tertiary production (Enhanced Oil Recovery). This equipment admixes polymers to flooding water which, in the foam of a fluid flow, is guided through a pipeline 20 and is fed by (omitted} pumps through (omitted) injection boreholes in the oil field into an (omitted) oil site in order to drive the petroleum out of the rocks. Preferably the polymers are fed as an aqueous polymer solution to the flooding water which shall be pumped at a predetermined viscosity to the oil sited.
Accordingly the equipment 10 is an injection or admixing equipment admixing the polymer solution at a defined rate as well as at a controllable pressure to the flowing water without however destroying the molecular structures of the typically very long and heavy polymers.
The control 40 comprises a valve system 50 to allow metering the polymer solution into the flooding water. Said valve system is designed in a way that, following each operational setting of an adjustment cylinder 51—which is powered by a drive 60—a defined number of feed conduits 70 are opened or closed. Accordingly the rate of the polymer solution fed into the flooding water and latter's viscosity may be adjusted accurately by means of the controlled opening and closing of a given number and a given kind of feed conduits 70 that are configured between the control 40 and the feed lance 30 respectively the pipeline 20.
As shown further in
Preferably the static mixers 80, 81 within a feed conduit 70 are of different lengths, as a result of which a defined pressure drop and laminar flow shall set in at the particular feed conduits across a given length of path. More than the length of the static mixers 80, 81 may be varied. Their number and or the configuration of the mixing elements may be different, depending on the magnitude of the pressure drop, the degree of mixing and the kind of flow to be attained within a feed conduit 70. Illustratively, two different static mixers 80, 81 are used in the uppermost feed conduit 70 of
A substantially cylindrical cavity 45 is subtended within the housing 43 and receives the adjustment cylinder 51 in the region of the surfaces 44 receiving the flanged plates 74. Said adjustment cylinder is supported in rotatable manner about longitudinal axis A of the control 40 within the cavity 45, a regulating spindle 541 passing through a gland-packed bearing sleeve 53 to the outside where its end 542 is connected to the drive 60 which may be mechanical, hydraulic, pneumatic or electrical.
The adjustment cylinder 51 comprises a central, longitudinal recess 55 (not shown in detail in
Also a through-borehole 46 is present in each feed conduit 70 in the lateral surfaces 44 of the control 40, whereas congruent through-boreholes 76 are present in each flanged plate 74 and are each connected flow-wise to an associated feed conduit 70. Accordingly, for an appropriate angular position of the adjustment cylinder 51, the polymer solution fed through the flanged hookup 41 to the control 40 initially is able to flow through said cylinder's longitudinal recess 55 into an open control aperture 52 in the adjustment cylinder 51. From there the polymer solution passes through the associated through-borehole 46 in the wall 44 and the associated through-borehole 76 in a flanged plate 74 into the particular, associated feed conduit. The latter feed conduit then guides the polymer solution in laminar flow and at defined pressure through the feed lance 30 to the fluid flow in the pipeline 20.
Just as the ends 71 of the feed conduits 70, the through-boreholes 46 and 76 illustratively are configured linearly in a row, the feed conduits 70 preferably running parallel to each other at a constant spacing. This design assures a simple geometry both of the feed lance 30 and the control 40 which together may be made narrow. However, if needed, the through-boreholes 46, 76 and the feed conduits 70 may be arrayed otherwise, for instance being mutually staggered, or adjacent at a slant, or as a matrix. Appropriately too, depending on the size of the control 40, several more flanged plates 74 may be configured at a lateral surface 44 as indicated in
Just as the feed conduits 70 have different diameters, so the control apertures 52 are of different sizes, the size of a control aperture being made to match that of the particular feed conduit 70 in order that the adjustment cylinder 51 be able to always completely close and open the pertinent feed conduit 70. Moreover the control apertures 52 are elongated holes/slots, as a result of which a feed conduit 70 may remain open even after further rotation or displacement of the adjustment cylinder 51. Accordingly several feed conduits 70 may be opened simultaneously, illustratively to increase the input rate of polymer solution to the pipeline 20 (also see
Accordingly, the adjustment cylinder 51 of the control 40—by means of its control apertures 52 and jointly with the through-boreholes 46, 76 in the lateral surfaces 44 of the housing 43 resp. in the flanged plates 74 for the feed conduits 70—constitutes a valve system 50 by means of which the rate of polymer solution fed into the fluid flow can be metered accurately and precisely, namely in that the adjustment cylinder 51 opens the feed conduits 70 consecutively or simultaneously. Said adjustment cylinder moreover tangentially opening and closing the apertures 52, the polymers are not exposed to shearing forces when the control 40 is opened and closed. No turbulence or other mechanical stresses arise either in the adjustment cylinder 51 or in the feed conduits 70, and consequently the polymers undergo no damage within the equipment 10 of the present invention. Instead, the polymer solution moves virtually free of mechanical stresses into the feed conduits 70 and then passes through them and the static mixers 80, 81 therein, directly into the pipeline 20.
The static mixers 80 reduce the pressure within the feed conduits 70, as a result of which the polymer solution guided through the particular feed conduit 70 shall be fed at a predeterminable pressure into the feed lance 30 or into the pipeline 20. Accordingly the pressure differential between the polymer solution and the flooding water may be adjusted optimally. At the same time the static mixers 80 within the feed conduits 70 generate laminar flow, whereby the polymers are not being injected into the flooding water, but instead are introduced cautiously into it.
No longer are shear forces acting on the polymers dissolved in the polymer solution. The polymers' molecular chains remain wholly intact within the entire equipment 10, as a result of which the flooding water's viscosity can be accurately set.
The equipment 10 as a whole may be made comparatively compact, in particular the feed conduits 70 do not require being of a mandatory minimum length. Instead they may be made to be fairly short, whereby the spacing between the control 40 and the pipeline 20 is kept relatively short too. In the zone of the mouths of the feed conduits 70 or of the feed lance 30, said pipeline may serve as a connector and be fitted terminally with flanged hookups 22. In this way, the hookup may be integrated, even retrofitted, conveniently into a substantially large pipeline or a substantially large pipe union. Consequently the equipment 10 as a whole also may be retrofitted in pre-existing systems.
It is important that, depending on need, several feed conduits 70 can be connected to each side of the control 40 and be guided and shaped in a manner that the ends 702 of the conduits 70 facing the feed lance 30 issue as a row, laterally adjacent to each other, into the feed lance 30, or, as shown in the embodiment mode of
The feed conduits 70 may be rigid and/or at least in segments, the shape and the layout of said conduits being matched or matchable to the particulars of the installation of the equipment 10.
In order to seal the flanged plates 74 relative to the receiving surfaces 44 of the control 40, seals 79 (
The cavity 45 of the housing 43 receiving the adjustment cylinder 51 optionally may be clad with HDPE (Teflon) is indicated in
The ends 702 of the feed conduits 70 also may be affixed on a common (omitted) flanged plate that is laterally affixed to the feed lance 30 or to the pipeline 20.
Illustrative operation of the equipment 10 of the invention is discussed below:
The polymer solution to be regulated resp. admixed to the fluid flow is moved through the flanged hookup 41 at the input zone of the housing 43, the adjustment cylinder 51 initially being kept by the electric drive 60 in the closed position in which all accesses 52, 46, 76 to the feed conduits 70 are closed.
By means of a definable number n of electrical control signals, a number n of definable spindle positions may be generated using appropriate rotational displacements of the adjustment cylinder 51. One rotary spindle position is firmly associated to each control signal value, a fixed number n of pairs of values being obtained. The adjustment behavior of the adjustment cylinder 51 may be considered being quasi-analogous and it is used foremost to regulate the rate of the polymer solution while possibly having n analog steps. The flow-friendly design of the adjustment cylinder 51 precludes any reduction in pressure.
Accordingly the diverse spindle positions entail opening one or more aperture cross-section(s) 52, 46, 76 which are directly connected by sealing, frictional liners (not discussed further here) resp. flanged plates to the individual feed conduits 70 (
In summary, due to each driven pair of values (electric control power/spindle position), immediately thereupon one or more feed conduits 70 shall be opened, crossed by the polymer solution, and moved through the individual feed conduits 70 into the fluid flow, the integrated static mixers 80, 81 generating a given pressure reduction in the partial flow.
Lastly all feed conduits 70 issue either into collecting pipe (feed lance) 30 or directly into the pipeline 20.
In this manner a quantity Q can be regulated precisely in n analog steps within the entire pressure reducing system and at the same time a fixed total pressure loss Δp can be set by said system while observing the largest admissible shear stresses within the polymer solution that are in partial flows metered into the flooding water.
All features and advantages explicit in and implicit from the claims, the specification and the drawing, inclusive detail particulars, spatial configurations and method steps, may be construed being inventive per se as well as in arbitrary combinations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2011 011 214.6 | Feb 2011 | DE | national |
